wind auroral zone: Topics by Science.gov

Solar wind control of auroral zone geomagnetic activity

NASA Technical Reports Server (NTRS)

Clauer, C. R.; Mcpherron, R. L.; Searls, C.; Kivelson, M. G.

1981-01-01

Solar wind magnetosphere energy coupling functions are analyzed using linear prediction filtering with 2.5 minute data. The relationship of auroral zone geomagnetic activity to solar wind power input functions are examined, and a least squares prediction filter, or impulse response function is designed from the data. Computed impulse response functions are observed to have characteristics of a low pass filter with time delay. The AL index is found well related to solar wind energy functions, although the AU index shows a poor relationship. High frequency variations of auroral indices and substorm expansions are not predictable with solar wind information alone, suggesting influence by internal magnetospheric processes. Finally, the epsilon parameter shows a poorer relationship with auroral geomagnetic activity than a power parameter, having a VBs solar wind dependency.
Observations of neutral winds in the auroral E region during the magnetospheric storm of August 3-9, 1972

NASA Technical Reports Server (NTRS)

Brekke, A.; Doupnik, J. R.; Banks, P. M.

1974-01-01

Auroral zone E-region neutral winds have been derived from simultaneous measurements of ion drift velocities in different altitudes by the incoherent radar facility at Chatanika, Alaska, on a quiet day before and during the great magnetospheric storm of Aug. 3-9, 1972. The neutral wind expected for a day-night pressure asymmetry appears to be strongly opposed by ion drag and local pressure gradients in the auroral oval.
Stellar Ablation of Planetary Atmospheres

NASA Technical Reports Server (NTRS)

Moore, Thomas E.; Horwitz, J. L.

2007-01-01

We review observations and theories of the solar ablation of planetary atmospheres, focusing on the terrestrial case where a large magnetosphere holds off the solar wind, so that there is little direct atmospheric impact, but also couples the solar wind electromagnetically to the auroral zones. We consider the photothermal escape flows known as the polar wind or refilling flows, the enhanced mass flux escape flows that result from localized solar wind energy dissipation in the auroral zones, and the resultant enhanced neutral atom escape flows. We term these latter two escape flows the "auroral wind." We review observations and theories of the heating and acceleration of auroral winds, including energy inputs from precipitating particles, electromagnetic energy flux at magnetohydrodynamic and plasma wave frequencies, and acceleration by parallel electric fields and by convection pickup processes also known as "centrifugal acceleration." We consider also the global circulation of ionospheric plasmas within the magnetosphere, their participation in magnetospheric disturbances as absorbers of momentum and energy, and their ultimate loss from the magnetosphere into the downstream solar wind, loading reconnection processes that occur at high altitudes near the magnetospheric boundaries. We consider the role of planetary magnetization and the accumulating evidence of stellar ablation of extrasolar planetary atmospheres. Finally, we suggest and discuss future needs for both the theory and observation of the planetary ionospheres and their role in solar wind interactions, to achieve the generality required for a predictive science of the coupling of stellar and planetary atmospheres over the full range of possible conditions.
Monitoring Auroral Electrojet from Polar Cap Stations

NASA Astrophysics Data System (ADS)

Tan, A.; Lyatsky, W.; Lyatskaya, S.

2004-12-01

The auroral electrojet AL and AE geomagnetic activity indices are important for monitoring geomagnetic substorms. In the northern hemisphere these indices are derived from measurements at a set of geomagnetic observatories located in the auroral zone. In the southern hemisphere the major portion of the auroral zone is located on the ocean; this does not allow us to derive the auroral electrojet indices in the same way. We showed that monitoring the auroral electrojet is possible from magnetic field measurements at polar cap stations. For this purpose we used hourly values of geomagnetic field variations at four polar cap stations, distributed along polar cap boundary and occupying a longitudinal sector of about 14 hours, and calculated mean values of the total magnetic field disturbance T = (X2 + Y2 + Z2)1/2 where X, Y, and Z are geomagnetic field components measured at these polar cap stations. The set of the obtained values were called the T index. This index has a clear physical mining: it is the summary of geomagnetic disturbance in all three components averaged over the polar cap boundary. We found that correlation coefficients for the dependence of the T index on both AL and AE indices are as high as ~0.9 and higher. The high correlation of the T index with the AL and AE indices takes place for any UT hour when the stations were located at the night side. The T index further shows good correlation with solar wind parameters: the correlation coefficient for the dependence of the T index on the solar wind-geomagnetic activity coupling function is ~0.8 and higher, which is close to the correlation coefficient for AL index. The T index may be especially important in the cases when ground-based measurements in the auroral zone are impossible as in the southern hemisphere.
Global Auroral Energy Deposition during Substorm Onset Compared with Local Time and Solar Wind IMF Conditions

NASA Technical Reports Server (NTRS)

Spann, J. F.; Brittnacher, M.; Fillingim, M. O.; Germany, G. A.; Parks, G. K.

1998-01-01

The global images made by the Ultraviolet Imager (UVI) aboard the IASTP/Polar Satellite are used to derive the global auroral energy deposited in the ionosphere resulting from electron precipitation. During a substorm onset, the energy deposited and its location in local time are compared to the solar wind IMF conditions. Previously, insitu measurements of low orbiting satellites have made precipitating particle measurements along the spacecraft track and global images of the auroral zone, without the ability to quantify energy parameters, have been available. However, usage of the high temporal, spatial, and spectral resolution of consecutive UVI images enables quantitative measurement of the energy deposited in the ionosphere not previously available on a global scale. Data over an extended period beginning in January 1997 will be presented.
Lyman alpha line shapes from electron impact H2 dissociative processes in the Jovian auroral zone

NASA Technical Reports Server (NTRS)

Waite, J. H., Jr.; Gladstone, G. R.

1992-01-01

Over the past two years several Lyman alpha line profile spectra of Jupiter were obtained using the International Ultraviolet Explorer (IUE) telescope. Several different regions of the planet were observed including the auroral zone, the low and mid latitudes, and the equatorial region which includes the Lyman alpha bulge region. These results have presented a very interesting picture of atomic hydrogen on Jupiter with explanations that range from ion outflow in the auroral zone to large thermospheric winds at low and mid latitudes. New data are needed to address the outstanding questions. Almost certainly, high resolution spectra from the Hubble Space Telescope will play a role in new observations. Better data also require better models, and better models require new laboratory data as inputs. The purpose of this program is two-fold: (1) to introduce a method by which new laboratory electron impact measurements of H2 dissociation can be used to calculate both the slow and fast H(S-2) and H(P-2) fragments in an H2 atmosphere; and (2) to determine the predicted Lyman alpha line shape that would result from electron impact production of these dissociative fragments in the Jovian auroral zone.
CEDAR/TIMED: Thermospheric Vertical Wind Observations from Three Sites in the Northern Auroral Zone

NASA Technical Reports Server (NTRS)

Lummerzheim, D.

2005-01-01

The objective of this project was to operate ground based Fabry-Perot Interferometers at several points under the auroral zone to analyze and quantify the vertical wind in the thermosphere. These measurements were made in conjunction with TIMED, especially GUVI data, to relate the observed wind to the resulting mixing and compositional changes in the thermosphere. The ground based wind measurements were obtained from a scanning Doppler imager (SDI) in Poker Flat, and a vertically aligned Fabry Perot Imager (FPI) in Inuvik. A third FPI at Eagle, Alaska, was operated for a brief overlapping period as well. The SDI at Poker Flat had been in operation for several years, and was continued to run with little support from this grant. The much more expensive operation, maintenance, and data acquisition of the remote Inuvik FPI was made possible with funds from this project. During the 2003/2004 and 2004/2005 seasons, we operated the Inuvik FPI from September to April during hours of darkness. Two trips to service the instrument were required per year, and a local caretaker was funded to help keep the instrument going during the winter seasons. The data were transfered via modem and phone line to Poker Flat and were then analyzed to obtain wind and temperature at the altitude of the auroral green line OI(557.7 nm). The final data product was archived and transferred to the GEDDS system at Poker Flat were it is available on the web: http://gedds.pfrr.alaska.edu/. The data set is also available from the CEDAR data base: http://cedarweb.hao.ucar.edu/.
Jupiter's outer atmosphere.

NASA Technical Reports Server (NTRS)

Brice, N. M.

1973-01-01

The current state of the theory of Jupiter's outer atmosphere is briefly reviewed. The similarities and dissimilarities between the terrestrial and Jovian upper atmospheres are discussed, including the interaction of the solar wind with the planetary magnetic fields. Estimates of Jovian parameters are given, including magnetosphere and auroral zone sizes, ionospheric conductivity, energy inputs, and solar wind parameters at Jupiter. The influence of the large centrifugal force on the cold plasma distribution is considered. The Jovian Van Allen belt is attributed to solar wind particles diffused in toward the planet by dynamo electric fields from ionospheric neutral winds, and the consequences of this theory are indicated.
Influence of interplanetary magnetic field and solar wind on auroral brightness in different regions

NASA Astrophysics Data System (ADS)

Yang, Y. F.; Lu, J. Y.; Wang, J.-S.; Peng, Z.; Zhou, L.

2013-01-01

AbstractBy integrating and averaging the auroral brightness from Polar Ultraviolet Imager auroral images, which have the whole auroral ovals, and combining the observation data of interplanetary magnetic field (IMF) and solar wind from NASA Operating Missions as a Node on the Internet (OMNI), we investigate the influence of IMF and solar wind on auroral activities, and analyze the separate roles of the solar wind dynamic pressure, density, and velocity on aurora, respectively. We statistically analyze the relations between the interplanetary conditions and the auroral brightness in dawnside, dayside, duskside, and nightside. It is found that the three components of the IMF have different effects on the auroral brightness in the different regions. Different from the nightside auroral brightness, the dawnside, dayside, and duskside auroral brightness are affected by the IMF Bx, and By components more significantly. The IMF Bx and By components have different effects on these three regional auroral brightness under the opposite polarities of the IMF Bz. As expected, the nightside aurora is mainly affected by the IMF Bz, and under southward IMF, the larger the |Bz|, the brighter the nightside aurora. The IMF Bx and By components have no visible effects. On the other hand, it is also found that the aurora is not intensified singly with the increase of the solar wind dynamic pressure: when only the dynamic pressure is high, but the solar wind velocity is not very fast, the aurora will not necessarily be intensified significantly. These results can be used to qualitatively predict the auroral activities in different regions for various interplanetary conditions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820028333&hterms=1087&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231087','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820028333&hterms=1087&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231087">Correlations between solar wind parameters and auroral kilometric radiation intensity</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gallagher, D. L.; Dangelo, N. 1981-01-01 The relationship between solar wind properties and the influx of energy into the nightside auroral region as indicated by the intensity of auroral kilometric radiation is investigated. Smoothed Hawkeye satellite observations of auroral radiation at 178, 100 and 56.2 kHz for days 160 through 365 of 1974 are compared with solar wind data from the composite Solar Wind Plasma Data Set, most of which was supplied by the IMP-8 spacecraft. Correlations are made between smoothed daily averages of solar wind ion density, bulk flow speed, total IMF strength, electric field, solar wind speed in the southward direction, solar wind speed multiplied by total IMF strength, the substorm parameter epsilon and the Kp index. The greatest correlation is found between solar wind bulk flow speed and auroral radiation intensity, with a linear correlation coefficient of 0.78 for the 203 daily averages examined. A possible mechanism for the relationship may be related to the propagation into the nightside magnetosphere of low-frequency long-wavelength electrostatic waves produced in the magnetosheath by the solar wind. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830033749&hterms=1091&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231091','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830033749&hterms=1091&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231091">Transport of aurorally produced N/2D/ by winds in the high latitude thermosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gerard, J.-C.; Roble, R. G. 1982-01-01 A time-dependent, two-dimensional model is developed for describing the meridional circulation of thermospheric odd nitrogen species produced in the auroral zone. The model is based on a previous model by Roble and Gary (1979) extended to upper altitude transport of the nitrogen species. Assumptions made include the existence of a steady neutral wind flowing from low to high latitudes, and an initial background due to scattered Lyman-beta and nightglow emissions. The aurora is also assumed as steady, along with a constant ion production. Predictions made using the model are compared with observations with the Atmosphere Explorer C spacecraft and rocket sounding measurements of the 5200 A distribution near the day-side polar cusp. The model requires thermospheric winds of 100-200 m/sec, flowing from day to nightside. Convective velocities near 1000 m/sec were detected by the Explorer spacecraft, as well as a day-to-nightside flow at the cusp. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.7668G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.7668G">Juno-UVS approach observations of Jupiter's auroras</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gladstone, G. R.; Versteeg, M. H.; Greathouse, T. K.; Hue, V.; Davis, M. W.; Gérard, J.-C.; Grodent, D. C.; Bonfond, B.; Nichols, J. D.; Wilson, R. J.; Hospodarsky, G. B.; Bolton, S. J.; Levin, S. M.; Connerney, J. E. P.; Adriani, A.; Kurth, W. S.; Mauk, B. H.; Valek, P.; McComas, D. J.; Orton, G. S.; Bagenal, F. 2017-08-01 Juno ultraviolet spectrograph (UVS) observations of Jupiter's aurora obtained during approach are presented. Prior to the bow shock crossing on 24 June 2016, the Juno approach provided a rare opportunity to correlate local solar wind conditions with Jovian auroral emissions. Some of Jupiter's auroral emissions are expected to be controlled or modified by local solar wind conditions. Here we compare synoptic Juno-UVS observations of Jupiter's auroral emissions, acquired during 3-29 June 2016, with in situ solar wind observations, and related Jupiter observations from Earth. Four large auroral brightening events are evident in the synoptic data, in which the total emitted auroral power increases by a factor of 3-4 for a few hours. Only one of these brightening events correlates well with large transient increases in solar wind ram pressure. The brightening events which are not associated with the solar wind generally have a risetime of 2 h and a decay time of 5 h. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28989207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28989207">Juno-UVS approach observations of Jupiter's auroras.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Gladstone, G R; Versteeg, M H; Greathouse, T K; Hue, V; Davis, M W; Gérard, J-C; Grodent, D C; Bonfond, B; Nichols, J D; Wilson, R J; Hospodarsky, G B; Bolton, S J; Levin, S M; Connerney, J E P; Adriani, A; Kurth, W S; Mauk, B H; Valek, P; McComas, D J; Orton, G S; Bagenal, F 2017-08-16 Juno ultraviolet spectrograph (UVS) observations of Jupiter's aurora obtained during approach are presented. Prior to the bow shock crossing on 24 June 2016, the Juno approach provided a rare opportunity to correlate local solar wind conditions with Jovian auroral emissions. Some of Jupiter's auroral emissions are expected to be controlled or modified by local solar wind conditions. Here we compare synoptic Juno-UVS observations of Jupiter's auroral emissions, acquired during 3-29 June 2016, with in situ solar wind observations, and related Jupiter observations from Earth. Four large auroral brightening events are evident in the synoptic data, in which the total emitted auroral power increases by a factor of 3-4 for a few hours. Only one of these brightening events correlates well with large transient increases in solar wind ram pressure. The brightening events which are not associated with the solar wind generally have a risetime of ~2 h and a decay time of ~5 h. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E3391T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E3391T">Magnetic substorms and northward IMF turning</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Troshichev, Oleg; Podorozhkina, Nataly To determine the relation of the northward IMF turnings to substorm sudden onsets, we separated all events with sharp northward IMF turnings observed in years of solar maximum (1999-2002) and solar minimum (2007-2008). The events (N=261) have been classified in 5 groups in accordance with average magnetic activity in auroral zone (low, moderate or high levels of AL index) at unchanged or slightly changed PC index and with dynamics of PC (steady distinct growth or distinct decline) at arbitrary values of AL index. Statistical analysis of relationships between the IMF turning and changes of PC and AL indices has been fulfilled separately for each of 5 classes. Results of the analysis showed that, irrespective of geophysical conditions and solar activity epoch, the magnetic activity in the polar caps and in the auroral zone demonstrate no response to the sudden northward IMF turning, if the moment of northward turning is taken as a key date. Sharp increases of magnetic disturbance in the auroral zone are observed only under conditions of the growing PC index and statistically they are related to moment of the PC index exceeding the threshold level (~1.5 mV/m), not to northward turnings timed, as a rule, after the moment of sudden onset. Magnetic disturbances observed in these cases in the auroral zone (magnetic substorms) are guided by behavior of the PC index, like to ordinary magnetic substorms or substorms developed under conditions of the prolonged northward IMF impact on the magnetosphere. The evident inconsistency between the sharp IMF changes measured outside of the magnetosphere and behavior of the ground-based PC index, the latter determining the substorm development, provides an additional argument in favor of the PC index as a ground-based proxy of the solar wind energy that entered into magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20180002925&hterms=Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSolar','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20180002925&hterms=Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DSolar">Dawn- Dusk Auroral Oval Oscillations Associated with High- Speed Solar Wind</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Liou, Kan; Sibeck, David G. 2018-01-01 We report evidence of global-scale auroral oval oscillations in the millihertz range, using global auroral images acquired from the Ultraviolet Imager on board the decommissioned Polar satellite and concurrent solar wind measurements. On the basis of two events (15 January 1999 and 6 January 2000) studied, it is found that (1) quasi-periodic auroral oval oscillations (approximately 3 megahertz) can occur when solar wind speeds are high at northward or southward interplanetary magnetic field turning, (2) the oscillation amplitudes range from a few to more than 10 degrees in latitudes, (3) the oscillation frequency is the same for each event irrespective of local time and without any azimuthal phase shift (i.e., propagation), (4) the auroral oscillations occur in phase within both the dawn and dusk sectors but 180 degrees out of phase between the dawn and dusk sectors, and (5) no micropulsations on the ground match the auroral oscillation periods. While solar wind conditions favor the growth of the Kelvin-Helmholtz (K-H) instability on the magnetopause as often suggested, the observed wave characteristics are not consistent with predictions for K-H waves. The in-phase and out-of-phase features found in the dawn-dusk auroral oval oscillations suggest that wiggling motions of the magnetotail associated with fast solar winds might be the direct cause of the global-scale millihertz auroral oval oscillations. Plain Language Summary: We utilize global auroral image data to infer the motion of the magnetosphere and show, for the first time, the entire magnetospheric tail can move east-west in harmony like a windsock flapping in wind. The characteristic period of the flapping motion may be a major source of global long-period ULF (Ultra Low Frequency) waves, adding an extra source of the global mode ULF waves. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA44A..01N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA44A..01N">Mesoscale thermospheric wind in response to nightside auroral brightening</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nishimura, T.; Zou, Y.; Gabrielse, C.; Lyons, L. R.; Varney, R. H.; Conde, M.; Hampton, D. L.; Mende, S. B. 2017-12-01 Although high-latitude ionospheric flows and thermospheric winds in the F-region are overall characterized by two-cell patterns over a global scale ( 1000 km), intense energy input from the magnetosphere often occurs in a mesoscale ( 100 km) and transient manner ( 10 min). Intense mesoscale energy input would drive enhanced mesoscale winds, whose properties are closely associated with auroral arcs and associated ionospheric flows. However, how thermospheric winds respond to and distribute around mesoscale magnetospheric input has not been characterized systematically. This presentation addresses how mesoscale winds distribute around quasi-steady arcs, evolve and distribute around transient arcs, and vary with geomagnetic and solar activity. We use Scanning Doppler Imagers (SDIs), all-sky imagers and PFISR over Alaska. A channel of azimuthal neutral wind is often found associated with localized flow channels adjacent to quasi-steady discrete aurora. The wind speed dynamically changes after a short time lag (a few tens of minutes) from auroral brightenings, including auroral streamers and intensifications on preexisting auroral arcs. This is in contrast to a much longer time lag ( 1 hour) reported previously. During a storm main phase, a coherent equatorward motion of the Harang discontinuity was seen in plasma flow, aurora and neutral wind, with a few degrees of equatorward displacement of the neutral wind Harang, which is probably due to the inertia. These results suggest that a tight M-I-T connection exists under the energy input of assorted auroral arcs and that mesoscale coupling processes are important in M-I-T energy transfer. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA127016','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA127016">MITHRAS: A Program of Simultaneous Radar Observations of the High-Latitude Auroral Zone.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1982-11-01 Latitude * and Time for Chatanika ..... ................. ... 38 111-5 Cross Polar Cap Potential Versus Solar-Wind Energy Parameter...49 vii 9 III-10 Scatter Plot of Pedersen Conductivities as a Function of Average Energy for Two Levels of Total...Precipitated Energy ....... ....... ......... .. 51 -IIl-1 For Initial Time and Steady State, (a) Latitudinal Profile of the Meridional Electric-Field </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5606505','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5606505">Juno‐UVS approach observations of Jupiter's auroras</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Versteeg, M. H.; Greathouse, T. K.; Hue, V.; Davis, M. W.; Gérard, J.‐C.; Grodent, D. C.; Bonfond, B.; Nichols, J. D.; Wilson, R. J.; Hospodarsky, G. B.; Bolton, S. J.; Levin, S. M.; Connerney, J. E. P.; Adriani, A.; Kurth, W. S.; Mauk, B. H.; Valek, P.; McComas, D. J.; Orton, G. S.; Bagenal, F. 2017-01-01 Abstract Juno ultraviolet spectrograph (UVS) observations of Jupiter's aurora obtained during approach are presented. Prior to the bow shock crossing on 24 June 2016, the Juno approach provided a rare opportunity to correlate local solar wind conditions with Jovian auroral emissions. Some of Jupiter's auroral emissions are expected to be controlled or modified by local solar wind conditions. Here we compare synoptic Juno‐UVS observations of Jupiter's auroral emissions, acquired during 3–29 June 2016, with in situ solar wind observations, and related Jupiter observations from Earth. Four large auroral brightening events are evident in the synoptic data, in which the total emitted auroral power increases by a factor of 3–4 for a few hours. Only one of these brightening events correlates well with large transient increases in solar wind ram pressure. The brightening events which are not associated with the solar wind generally have a risetime of ~2 h and a decay time of ~5 h. PMID:28989207 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020080690','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020080690">FAST/Polar Conjunction Study of Field-Aligned Auroral Acceleration and Corresponding Magnetotail Drivers</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Schriver, D.; Ashour-Abdalla, M.; Strangeway, R. J.; Richard, R. L.; Klezting, C.; Dotan, Y.; Wygant, J. 2002-01-01 The discrete aurora results when energized electrons bombard the Earth's atmosphere at high latitudes. This paper examines the physical processes that can cause field-aligned acceleration of plasma particles in the auroral region. A data and theoretical study has been carried out to examine the acceleration mechanisms that operate in the auroral zone and to identity the magnetospheric drivers of these acceleration mechanisms. The observations used in the study were collected by the Fast Auroral SnapshoT (FAST) and Polar satellites when the two satellites were in approximate magnetic conjunction in the auroral region. During these events FAST was in the middle of the auroral zone and Polar was above the auroral zone in the near-Earth plasma sheet. Polar data was used to determine the conditions in the magnetotail at the time field-aligned acceleration was measured by FAST in the auroral zone. For each of the magnetotail drivers identified in the data study, the physics of field-aligned acceleration in the auroral region was examined using existing theoretical efforts and a long-system particle-in-cell simulation to model the magnetically connected region between the two satellites. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040034085&hterms=project+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dproject%2Bwaves','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040034085&hterms=project+waves&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dproject%2Bwaves">The Consequences of Alfven Waves and Parallel Potential Drops in the Auroral Zone</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Schriver, David 2003-01-01 The goal of this research is to examine the causes of field-aligned plasma acceleration in the auroral zone using satellite data and numerical simulations. A primary question to be addressed is what causes the field-aligned acceleration of electrons (leading to precipitation) and ions (leading to upwelling ions) in the auroral zone. Data from the Fast Auroral SnapshoT (FAST) and Polar satellites is used when the two satellites are in approximate magnetic conjunction and are in the auroral region. FAST is at relatively low altitudes and samples plasma in the midst of the auroral acceleration region while Polar is at much higher altitudes and can measure plasmas and waves propagating towards the Earth. Polar can determine the sources of energy streaming earthward from the magnetotail, either in the form of field-aligned currents, electromagnetic waves or kinetic particle energy, that ultimately leads to the acceleration of plasma in the auroral zone. After identifying and examining several events, numerical simulations are run that bridges the spatial region between the two satellites. The code is a one-dimensional, long system length particle in cell simulation that has been developed to model the auroral region. A main goal of this research project is to include Alfven waves in the simulation to examine how these waves can accelerate plasma in the auroral zone. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li class="active">1</li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_2" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active">2</li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="21"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040068131&hterms=conjunctions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dconjunctions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040068131&hterms=conjunctions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dconjunctions">FAST/Polar Conjunction Study of Field-Aligned Auroral Acceleration and Corresponding Magnetotail Drivers</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Schriver, D.; Ashour-Abdalla, M.; Strangeway, R. J.; Richard, R. L.; Klezting, C.; Dotan, Y.; Wygant, J. 2003-01-01 The discrete aurora results when energized electrons bombard the Earth's atmosphere at high latitudes. This paper examines the physical processes that can cause field-aligned acceleration of plasma particles in the auroral region. A data and theoretical study has been carried out to examine the acceleration mechanisms that operate in the auroral zone and to identi@ the magnetospheric drivers of these acceleration mechanisms. The observations used in the study were collected by the Fast Auroral Snapshot (FAST) and Polar satellites when the two satellites were in approximate magnetic conjunction in the auroral region. During these events FAST was in the middle of the auroral zone and Polar was above the auroral zone in the near-Earth plasma sheet. Polar data were used to determine the conditions in the magnetotail at the time field-aligned acceleration was measured by FAST in the auroral zone. For each of the magnetotail drivers identified in the data study, the physics of field-aligned acceleration in the auroral region was examined using existing theoretical efforts and/or a long-system particle in cell simulation to model the magnetically connected region between the two satellites. Results from the study indicate that there are three main drivers of auroral acceleration: (1) field-aligned currents that lead to quasistatic parallel potential drops (parallel electric fields), (2) earthward flow of high-energy plasma beams from the magnetotail into the auroral zone that lead to quasistatic parallel potential drops, and (3) large-amplitude Alfven waves that propagate into the auroral region from the magnetotail. The events examined thus far confm the previously established invariant latitudinal dependence of the drivers and show a strong dependence on magnetic activity. Alfven waves tend to occur primarily at the poleward edge of the auroral region during more magnetically active times and are correlated with intense electron precipitation. At lower latitudes away from the poleward edge of the auroral zone is the primary field-aligned current region which results in the classical field- aligned acceleration associated with the auroral zone (electrons earthward and ion beams tailward). During times of high magnetic activity, high-energy ion beams originating from the magnetotail are observed within, and overlapping, the regions of primary and return field-aligned current. Along the field lines where the high-energy magnetotail ion beams are located, field-aligned acceleration can occur in the auroral zone leading to precipitating electrons and upwelling ionospheric ion beams. Field-aligned currents are present during both quiet and active times, while the Alfven waves and magnetotail ion beams were observed only during more magnetically active events. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870039720&hterms=current+feedback&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcurrent%2Bfeedback','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870039720&hterms=current+feedback&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dcurrent%2Bfeedback">Feedback between neutral winds and auroral arc electrodynamics</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lyons, L. R.; Walterscheid, R. L. 1986-01-01 The feedback between neutral atmospheric winds and the electrodynamics of a stable, discrete auroral arc is analyzed. The ionospheric current continuity equation and the equation for neutral gas acceleration by ion drag are solved simultaneously, as a function of time. The results show that, in general, the electric field in the ionosphere adjusts to neutral wind acceleration so as to keep auroral field-aligned currents and electron acceleration approximately independent of time. It is thus concluded that the neutral winds that develop as a result of the electrodynamical forcing associated with an arc do not significantly affect the intensity of the arc. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840044910&hterms=MOOS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DMOOS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840044910&hterms=MOOS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DMOOS">IUE observations of longitudinal and temporal variations in the Jovian auroral emission</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Skinner, T. E.; Durrance, S. T.; Feldman, P. D.; Moos, H. W. 1984-01-01 The IUE's short wavelength spectrograph has been used to monitor the auroral emissions from Jupiter's northern hemisphere, yielding eight observations between January 1981 and January 1982 of H I Lyman-alpha and the H2 Lyman and Werner bands. Attention is given to an apparent periodic emission flux fluctuation, through detailed modeling of the emission geometry. Two possible auroral zones are defined at the north pole by mapping the magnetic field lines from the Io torus and the magnetotail onto the planet's atmosphere. The observed variation in flux with central meridian longitude is not consistent with a uniform brightness as a function of magnetic longitude in either auroral zone. The data can be fitted by confining the emissions to the region of the northern torus auroral zone, in qualitative agreement with the magnetic anomaly model. A similar emission from the magnetotail auroral zone cannot be ruled out. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSA22A..05C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSA22A..05C">Optical remote sensing of penetration into the lower thermosphere of neutral wind and composition perturbations driven by magnetospheric forcing</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Conde, M. G.; Anderson, C.; Hecht, J. H. 2011-12-01 Numerous observations of thermospheric neutral winds at altitudes of 240 km and higher clearly show wind structures occurring at auroral latitudes in response to magnetospheric forcing. It is also known from observations that magnetospheric forcing is not a major driver of winds down at mesopause heights and below. Because it is difficult to measure winds in the intervening "transition region" between these height regimes, very little is known about how deeply the magnetospherically driven neutral wind structures penetrate into the lower thermosphere, what factors affect this penetration, and what consequences it may have for transport of chemical species. Here we will show neutral wind maps obtained at F-region and E-region heights in the auroral zone using Fabry-Perot Doppler spectroscopy of the 630 nm and 558 nm optical emissions. Although thermospheric neutral winds are smoothed by viscosity and inertia, observed responses to magnetospheric forcing still include wind responses on time scales as short as 10 minutes or less, and on length scales shorter than 100 km horizontally and 5 km vertically. The data also show that the degree of penetration of magnetospheric forcing into the lower thermospheric wind field is highly variable from day to day. Signatures of magnetospheric forcing are sometimes seen at altitudes as low as 120 km, whereas at other times the E-region does not seem to respond at all. Possible links will be explored between this variability and the day to day differences seen in the column integrated thermospheric [O]/[N2] ratio over Alaska. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DPS....4921102S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DPS....4921102S">Solar wind control of stratospheric temperatures in Jupiter's auroral regions?</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sinclair, James Andrew; Orton, Glenn; Kasaba, Yasumasa; Sato, Takao M.; Tao, Chihiro; Waite, J. Hunter; Cravens, Thomas; Houston, Stephen; Fletcher, Leigh; Irwin, Patrick; Greathouse, Thomas K. 2017-10-01 Auroral emissions are the process through which the interaction of a planet’s atmosphere and its external magnetosphere can be studied. Jupiter exhibits auroral emission at a multitude of wavelengths including the X-ray, ultraviolet and near-infrared. Enhanced emission of CH4 and other stratospheric hydrocarbons is also observed coincident with Jupiter’s shorter-wavelength auroral emission (e.g. Caldwell et al., 1980, Icarus 44, 667-675, Kostiuk et al., 1993, JGR 98, 18823). This indicates that auroral processes modify the thermal structure and composition of the auroral stratosphere. The exact mechanism responsible for this auroral-related heating of the stratosphere has however remained elusive (Sinclair et al., 2017a, Icarus 292, 182-207, Sinclair et al., 2017b, GRL, 44, 5345-5354). We will present an analysis of 7.8-μm images of Jupiter measured by COMICS (Cooled Mid-Infrared Camera and Spectrograph, Kataza et al., 2000, Proc. SPIE(4008), 1144-1152) on the Subaru telescope. These images were acquired on January 11th, 12th, 13th, 14th, February 4, 5th and May 17th, 18th, 19th and 20th in 2017, allowing the daily variability of Jupiter’s auroral-related stratospheric heating to be tracked. Preliminary results suggest lower stratospheric temperatures are directly forced by the solar wind dynamical pressure. The southern auroral hotspot exhibited a significant increase in brightness temperature over a 24-hour period. Over the same time period, a solar wind propagation model (Tao et al. 2005, JGR 110, A11208) predicts a strong increase in the solar wind dynamical pressure at Jupiter. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA43B2651Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA43B2651Z">Occurrence rate of ion upflow and downflow observed by the Poker Flat Incoherent Scatter Radar (PFISR)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zou, S.; Lu, J.; Varney, R. H. 2017-12-01 This study aims to investigate the occurrence rate of ion upflow and downflow events in the auroral ionosphere, using a full 3-year (2011-2013) dataset collected by the Poker Flat Incoherent Scatter Radar (PFISR) at 65.5° magnetic latitude. Ion upflow and downflow events are defined if there are three consecutive data points larger/smaller than 100/-100 m/s in the ion field-aligned velocity altitude profile. Their occurrence rates have been evaluated as a function of magnetic local time (MLT), season, geomagnetic activity, solar wind and interplanetary magnetic field (IMF). We found that the ion upflows are twice more likely to occur on the nightside than the dayside, and have slightly higher occurrence rate near Fall equinox. In contrast, the ion downflow events are more likely to occur in the afternoon sector but also during Fall equinox. In addition, the occurrence rate of ion upflows on the nightside increases when the aurora electrojet index (AE) and planetary K index (Kp) increase, while the downflows measured on the dayside clearly increase as the AE and Kp increase. In general, the occurrence rate of ion upflows increases with enhanced solar wind and IMF drivers. This correlation is particularly strong between the upflows on the nightside and the solar wind dynamic pressure and IMF Bz. The lack of correlation of upflows on the dayside with these parameters is due to the location of PFISR, which is usually equatorward of the dayside auroral zone and within the nightside auroral zone under disturbed conditions. The occurrence rate of downflow at all MLTs does not show strong dependence on the solar wind and IMF conditions. However, it occurs much more frequently on the dayside when the IMF By is strongly positive, i.e., >10 nT and the IMF Bz is strongly negative, i.e., < -10 nT. We suggest that the increased occurrence rate of downflows on the dayside is associated with dayside storm-enhanced density and the plume. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019853','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019853">Observations of vertical winds and the origin of thermospheric gravity waves launched by auroral substorms and westward travelling surges</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Rees, D. 1986-01-01 Several sequences of observations of strong vertical winds in the upper thermosphere are discussed, in conjunction with models of the generation of such winds. In the auroral oval, the strongest upward winds are observed in or close to regions of intense auroral precipitation and strong ionospheric currents. The strongest winds, of the order of 100 to 200 m/sec are usually upward, and are both localized and of relatively short duration (10 to 20 min). In regions adjacent to those displaying strong upward winds, and following periods of upward winds, downward winds of rather lower magnitude (40 to about 80 m/sec) may be observed. Strong and rapid changes of horizontal winds are correlated with these rapid vertical wind variations. Considered from a large scale viewpoint, this class of strongly time dependent winds propagate globally, and may be considered to be gravity waves launched from an auroral source. During periods of very disturbed geomagnetic activity, there may be regions within and close to the auroral oval where systematic vertical winds of the order of 50 m/sec will occur for periods of several hours. Such persistent winds are part of a very strong large scale horizontal wind circulation set up in the polar regions during a major geomagnetic disturbance. This second class of strong horizontal and vertical winds corresponds more to a standing wave than to a gravity wave, and it is not as effective as the first class in generating large scale propagating gravity waves and correlated horizontal and vertical oscillations. A third class of significant (10 to 30 m/sec) vertical winds can be associated with systematic features of the average geomagnetic energy and momentum input to the polar thermosphere, and appear in statistical studies of the average vertical wind as a function of Universal Time at a given location. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.2209Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.2209Y">Numerical simulation for a vortex street near the poleward boundary of the nighttime auroral oval</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yamamoto, T. 2012-02-01 The formation of a vortex street is numerically studied as an aftermath of a transient (≈1 min) depression of the energy density of injected particles. It is basically assumed that the kinetic energies of auroral particles are substantially provided by nonadiabatic acceleration in the tail current sheet. One of the causes of such energy density depression is an outward (away from the Earth) movement of the neutral line because in such situation, a particle passes the acceleration zone for a shorter time interval while it is inwardly transported in the current sheet. The numerical simulation shows that a long chain of many (≥5) vortices can be formed in the nighttime high-latitude auroral oval as a result of the hybrid Kelvin-Helmholtz/Rayleigh-Taylor (KH/RT) instability. The main characteristics of long vortex chains in the simulation such as the short lifetime (≲2 min) and the correlation between wavelength, λ, and arc system width, A, compare well with those of the periodic auroral distortions observed primarily in the high-latitude auroral oval. Specifically, either λ-A relationship from simulation or observation shows a positive correlation between λ and A but with considerable dispersion in λ. Since auroral vortices arising from the hybrid KH/RT instability are not accompanied by significant rotational motions, the magnetic shear instability caused by undulations in the field-aligned current (FAC) sheet could turn the vortices into spirals which wind or unwind in response to increase or decrease of FACs, respectively. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA128612','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA128612">Latitudinal Variations of Auroral-Zone Ionization Distribution.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1983-02-01 CONTRACT OR GRANT NUMBER(s) Robert M. Robinson F49620-80-C-0014 Roland T. Tsunoda 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT , PROJECT...scanned. A. Auroral Zone Ionospheric Conductivity A key element in modelling the magnetosphere-ionosphere circuit is the auroral zone ionospheric...while the maximum conductivity for the evening eastward electro- jet was less than 20 mho in our data set . In other words, both the south- ward field and </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040008860','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040008860">Polar Plasma Wave Investigation Data Analysis in the Extended Mission</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gurnett, Donald A.; Menietti, J. D. 2003-01-01 The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to l0(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross- diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040171316','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040171316">Polar Plasma Wave Investigation Data Analysis in the Extended Mission</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gurnett, Donald A. 2004-01-01 The low latitude boundary layer (LLBL) is a region where solar wind momentum and energy is transferred to the magnetosphere. Enhanced "broadband" electric plasma waves from less than 5 Hz to 10(exp 5) Hz and magnetic waves from less than 5 Hz to the electron cyclotron frequency are characteristic of the LLBL. Analyses of Polar plasma waves show that these "broadband" waves are actually discrete electrostatic and electromagnetic modes as well as solitary bipolar pulses (electron holes). It is noted that all wave modes can be generated by approx. 100 eV to approx. 10 keV auroral electrons and protons. We will review wave-particle interactions, with focus on cross-diffusion rates and the contributions of such interactions toward the formation of the boundary layer. In summary, we will present a scenario where the global solar wind-magnetosphere interaction is responsible for the auroral zone particle beams, and hence for the generation of plasma waves and the formation of the boundary layer. It is speculated that all planetary magnetospheres will have boundary layers and they will be characterized by similar currents and plasma wave modes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.1156V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.1156V">Solar wind influence on Jupiter's magnetosphere and aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vogt, Marissa; Gyalay, Szilard; Withers, Paul 2016-04-01 Jupiter's magnetosphere is often said to be rotationally driven, with strong centrifugal stresses due to large spatial scales and a rapid planetary rotation period. For example, the main auroral emission at Jupiter is not due to the magnetosphere-solar wind interaction but is driven by a system of corotation enforcement currents that arises to speed up outflowing Iogenic plasma. Additionally, processes like tail reconnection are also thought to be driven, at least in part, by processes internal to the magnetosphere. While the solar wind is generally expected to have only a small influence on Jupiter's magnetosphere and aurora, there is considerable observational evidence that the solar wind does affect the magnetopause standoff distance, auroral radio emissions, and the position and brightness of the UV auroral emissions. We will report on the results of a comprehensive, quantitative study of the influence of the solar wind on various magnetospheric data sets measured by the Galileo mission from 1996 to 2003. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter, we have identified intervals of high and low solar wind dynamic pressure. We can use this information to quantify how a magnetospheric compression affects the magnetospheric field configuration, which in turn will affect the ionospheric mapping of the main auroral emission. We also consider whether there is evidence that reconnection events occur preferentially during certain solar wind conditions or that the solar wind modulates the quasi-periodicity seen in the magnetic field dipolarizations and flow bursts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080031331&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DPlasma%2BRing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080031331&hterms=Plasma+Ring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DPlasma%2BRing">Simulating Sources of Superstorm Plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Fok, Mei-Ching 2008-01-01 We evaluated the contributions to magnetospheric pressure (ring current) of the solar wind, polar wind, auroral wind, and plasmaspheric wind, with the surprising result that the main phase pressure is dominated by plasmaspheric protons. We used global simulation fields from the LFM single fluid ideal MHD model. We embedded the Comprehensive Ring Current Model within it, driven by the LFM transpolar potential, and supplied with plasmas at its boundary including solar wind protons, polar wind protons, auroral wind O+, and plasmaspheric protons. We included auroral outflows and acceleration driven by the LFM ionospheric boundary condition, including parallel ion acceleration driven by upward currents. Our plasmasphere model runs within the CRCM and is driven by it. Ionospheric sources were treated using our Global Ion Kinetics code based on full equations of motion. This treatment neglects inertial loading and pressure exerted by the ionospheric plasmas, and will be superceded by multifluid simulations that include those effects. However, these simulations provide new insights into the respective role of ionospheric sources in storm-time magnetospheric dynamics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.6078R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.6078R">Stagnation of Saturn's auroral emission at noon</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Radioti, A.; Grodent, D.; Gérard, J.-C.; Southwood, D. J.; Chané, E.; Bonfond, B.; Pryor, W. 2017-06-01 Auroral emissions serve as a powerful tool to investigate the magnetospheric processes at Saturn. Solar wind and internally driven processes largely control Saturn's auroral morphology. The main auroral emission at Saturn is suggested to be connected with the magnetosphere-solar wind interaction, through the flow shear related to rotational dynamics. Dawn auroral enhancements are associated with intense field-aligned currents generated by hot tenuous plasma carried toward the planet in fast moving flux tubes as they return from tail reconnection site to the dayside. In this work we demonstrate, based on Cassini auroral observations, that the main auroral emission at Saturn, as it rotates from midnight to dusk via noon, occasionally stagnates near noon over a couple of hours. In half of the sequences examined, the auroral emission is blocked close to noon, while in three out of four cases, the blockage of the auroral emission is accompanied with signatures of dayside reconnection. We discuss some possible interpretations of the auroral "blockage" near noon. According to the first one, it could be related to local time variations of the flow shear close to noon. Auroral local time variations are also suggested to be initiated by radial transport process. Alternatively, the auroral blockage at noon could be associated with a plasma circulation theory, according to which tenuously populated closed flux tubes as they return from the nightside to the morning sector experience a blockage in the equatorial plane and they cannot rotate beyond noon. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM23C4246S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM23C4246S">Generation of BBFs and DFs, Formation of Substorm Auroras and Triggers of Substorm Onset</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Song, Y.; Lysak, R. L. 2014-12-01 Substorm onset is a dynamical response of the MI coupling system to external solar wind driving conditions and to internal dynamical processes. During the growth phase, the solar wind energy and momentum are transferred into the magnetosphere via MHD mesoscale Alfvenic interactions throughout the magnetopause current sheet. A decrease in momentum transfer from the solar wind into the magnetosphere starts a preconditioning stage, and produces a strong earthward body force acting on the whole magnetotail within a short time period. The strong earthward force will cause localized transients in the tail, such as multiple BBFs, DFs, plasma bubbles, and excited MHD waves. On auroral flux tubes, FACs carried by Alfven waves are generated by Alfvenic interactions between tail earthward flows associated with BBFs/DFs/Bubbles and the ionospheric drag. Nonlinear Alfvenic interaction between the incident and reflected Alfven wave packets in the auroral acceleration region can produce localized parallel electric fields and substorm auroral arcs. During the preconditioning stage prior to substorm onset, the generation of parallel electric fields and auroral arcs can redistribute perpendicular mechanical and magnetic stresses, "decoupling" the magnetosphere from the ionosphere drag. This will enhance the tail earthward flows and rapidly build up stronger parallel electric fields in the auroral acceleration region, leading to a sudden and violent tail energy release and substorm auroral poleward expansion. We suggest that in preconditioning stage, the decrease in the solar wind momentum transfer is a necessary condition of the substorm onset. Additionally, "decoupling" the magnetosphere from ionosphere drag can trigger substorm expansion onset. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.3900K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.3900K">Measurements of Ion-Neutral Coupling in the Auroral F Region in Response to Increases in Particle Precipitation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kiene, A.; Bristow, W. A.; Conde, M. G.; Hampton, D. L. 2018-05-01 Neutral winds are a key factor in the dynamics of the ionosphere-thermosphere system. Previous observations have shown that neutral and ion flows are strongly coupled during periods of auroral activity when ion drag forcing can become the dominant force driving neutral wind flow. This is primarily due to increases in ion density due to enhanced particle precipitation as well as associated increases the strength of the electric fields that drive ion motions. Due to this strong coupling, numerical simulations of neutral dynamics have difficulty reproducing neutral wind observations when they are driven by modeled precipitation and modeled convection. It is therefore desirable whenever possible to have concurrent coincident measurements of auroral precipitation and ion convection. Recent advancements in high-resolution fitting of Super Dual Auroral Radar Network ion convection data have enabled the generation of steady maps of ion drifts over Alaska, coinciding with several optics sites. The Super Dual Auroral Radar Network measurements are compared with scanning Doppler imager neutral wind measurements at similar altitude, providing direct comparisons of ion and neutral velocities over a wide field and for long periods throughout the night. Also present are a digital all-sky imager and a meridian spectrograph, both of which provide measurements of auroral intensity on several wavelengths. In this study, we combine these data sets to present three case studies that show significant correlation between increases in F region precipitation and enhancements in ion-neutral coupling in the evening sector. We investigate the time scales over which the coupling takes place and compare our findings to previous measurements. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810006430','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810006430">Spacelab experiment: ALAE, Atmospheric Lyman-Alpha Emissions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 1980-01-01 A spectrophotometer associated with two absorption cells, one filled with hydrogen and the other with deuterium, is described for use in studying various sources of Lyman-alpha emission in the atmosphere, in the interplanetary medium, and possibly in the galactic medium. As the result of charge exchange, Lyman-alpha emission is possibly present in auroral zones, equatorial zones, and at the foot of the polar cusp, where the solar wind interacts directly with the neutral atmosphere. Some emission is also expected from the plasma guns on board Spacelab. The use of the absorption cell is also a test for determining if the presence of geocoronal and interplanetary emission will prevent future astronomical observations of Lyman-alpha emissions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030061175&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DFord','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030061175&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DFord">Preliminary Results from Recent Simultaneous Chandra/HST Observations of Jupiter Auroral Zones</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Elsner, R.; Gladstone, R.; Waite, H.; Majeed, T.; Ford, P.; Grodent, D.; Bwardwaj, A.; Howell, R.; Cravens, T.; MacDowell, R. 2003-01-01 Jupiter was observed by the Chandra X-ray Observatory in late February, 2003, for 144 ks, using both the ACIS-S and HRC-I imaging x-ray cameras. Five orbits of HST STIS observations of the planet's northern auroral zone were obtained during the ACIS-S observations. These data are providing a wealth of information about Jupiter's auroral activity, including the first x-ray spectra from the x-ray hot spots inside the auroral ovals. We will also discuss the approximately 45 minute quasi-periodicity in the auroral x-ray emission - which correlates well with simultaneous observations of radio bursts by the Ulysses spacecraft - and a possible phase relation between the emission from the northern and southern x-ray aurora. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820055781&hterms=theoretical+physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtheoretical%2Bphysics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820055781&hterms=theoretical+physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dtheoretical%2Bphysics">Highlights of theoretical progress related to the International Magnetospheric Study</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hill, T. W. 1982-01-01 U.S. theoretical research efforts have addressed three areas within the International Magnetospheric Study. The first, solar wind/magnetosphere interaction, is presently concerned with the suggestion that magnetic merging may predominantly occur near the polar cusps rather than near the subsolar point. Mechanisms have been proposed for noncollisional diffusion of solar wind plasma across the closed magnetopause entailed by such a phenomenon. The second area considers the importance to magnetotail dynamics of a continuous source of solar wind plasma, and of sporadic plasma loss associated with an unsteady convection cycle. In the third area, the electrodynamic magnetosphere/ionosphere interaction, an advanced state has been reached in the understanding of the relevant physics, with respect both to coupling in the subauroral region and the large scale structure of auroral zone electric fields parallel, and perpendicular to, the magnetic field. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123..385L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123..385L">The Effects of Solar Wind Dynamic Pressure Changes on the Substorm Auroras and Energetic Electron Injections on 24 August 2005</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Li, L. Y.; Wang, Z. Q. 2018-01-01 After the passage of an interplanetary (IP) shock at 06:13 UT on 24 August 2005, the enhancement (>6 nPa) of solar wind dynamic pressure and the southward turning of interplanetary magnetic field (IMF) cause the earthward movement of dayside magnetopause and the drift loss of energetic particles near geosynchronous orbit. The persistent electron drift loss makes the geosynchronous satellites cannot observe the substorm electron injection phenomenon during the two substorm expansion phases (06:57-07:39 UT) on that day. Behind the IP shock, the fluctuations ( 0.5-3 nPa) of solar wind dynamic pressure not only alter the dayside auroral brightness but also cause the entire auroral oval to swing in the day-night direction. However, there is no Pi2 pulsation in the nightside auroral oval during the substorm growth phase from 06:13 to 06:57 UT. During the subsequent two substorm expansion phases, the substorm expansion activities cause the nightside aurora oval brightening from substorm onset site to higher latitudes, and meanwhile, the enhancement (decline) of solar wind dynamic pressure makes the nightside auroral oval move toward the magnetic equator (the magnetic pole). These observations demonstrate that solar wind dynamic pressure changes and substorm expansion activities can jointly control the luminosity and location of the nightside auroral oval when the internal and external disturbances occur simultaneously. During the impact of a strong IP shock, the earthward movement of dayside magnetopause probably causes the disappearance of the substorm electron injections near geosynchronous orbit. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li class="active">2</li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_3" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active">3</li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="41"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010108000','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010108000">Auroral, Polar Cap, and Polar Cusp Modeling and Data Analysis for the IMAGE Mission and LENA Instrument</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Wilson, Gordon R. 2001-01-01 One of the chief mysteries in the LENA perigee pass data is the lack of an apparent auroral oval in the images. Another is that in some cases ENA are seen from any direction near the Earth regardless of the latitude of the spacecraft. These facts lead one to ask a fundamental question: Is the instrument responding to ENA primarily? One possible way to get out of the "ambiguity" of the data is to assume that at least part of the signal is produced by something other than ENA. The two main candidates for this "something else" are UV light and energetic charged particles. UV light could only effect the instrument when its fan shaped aperture points toward the source. The most intense of which will be the sun, with day glow being the second strongest and the auroral zone, the third. We can rule out UV light as a prime source of counts in the perigee pass data for the following reasons: 1) The perigee pass signal is different in form and much stronger than the sun pulse signal seen just before or just after perigee; 2) There is no indication of the auroral zone, which would produce at least two peaks in the counts versus spin phase curve; 3) Mike Colliers' analysis of the sun pulse signal shows that it varies with the flux of the solar wind and not with variations in the solar UV flux. Charge particles that enter the aperture of the instrument and produce counts would show up when the instrument looks in the direction from which they come. In all of the data I am analyzing voltages were being applied to the collimators so that most charged particles should have been excluded from the instrument but this effect could still show up where the flux of energetic particles is high enough. The most likely place would be in the auroral zone where energetic electrons and protons precipitate. If these particles are producing counts then they should be seen when the instrument looks in and near the zenith direction. In nearly all of the perigee passes the zenith direction is devoid of counts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080037609&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080037609&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsolar%2Bintensity%2Bmeasurement">Saturn's Auroral Response to the Solar Wind: Centrifugal Instability Model</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sittler, Edward C.; Blanc, Michel F.; Richardson, J. D. 2008-01-01 We describe a model initially presented by Sittler et al. [2006] which attempts to explain the global response of Saturn's magnetosphere and its corresponding auroral behavior to variations in the solar wind. The model was derived from published simultaneous Hubble Space Telescope (HST) auroral images and Cassini upstream measurements taken during the month of January 2004. These observations show a direct correlation between solar wind dynamic pressure and (1) auroral brightening toward dawn local time, (2) an increase of rotational movement of auroral features to as much as 75% of the corotation speed, (3) the movement of the auroral oval to higher latitudes and (4) an increase in the intensity of Saturn Kilometric Radiation (SKR). This model is an alternative to the reconnection model of Cowley et al. [2004a,b; 2005] which is more Earth-like while ours stresses rotation. If angular momentum is conserved in a global sense, then when compressed the magnetosphere will tend to spin up and when it expands will tend to spin down. With the plasma sheet outer boundary at L approximates 15 we argue this region to be the dominant source region for the precipitating particles. If radial transport is dominated by centrifugal driven flux tube interchange motions, then when the magnetosphere spins up, outward transport will increase, the precipitating particles will move radially outward and cause the auroral oval to move to higher latitudes as observed. The Kelvin-Helmholtz instability may contribute to the enhanced emission along the dawn meridian as observed by HST. We present this model in the context of presently published observations by Cassini. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740027122','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740027122">Study of the relation between Pc 3 micropulsations and magnetosheath fluctuations and for the multisatellite multimeasurement investigation of earths bow shock</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Greenstadt, E. W. 1974-01-01 Hourly averages of HEOS A interplanetary field and plasma parameters are compared with micropulsation spectrograms taken by auroral zone stations. Visual evaluation of tungsten induction coil records and a statistical summary indicate a class of pulsations sometimes in the Pc 3, sometimes in the Pc 4 range, whose appearance correlates with solar wind field flow alignment. It is concluded that there is a pulsation phenomenon of variable period strongly associated with certain interplanetary field directions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003hst..prop10083C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003hst..prop10083C">HST UV Images of Saturn's Aurora Coordinated with Cassini Solar Wind Measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Clarke, John 2003-07-01 A key measurement goal of the Cassini mission to Saturn is to obtain simultaneous solar wind and auroral imaging measurements in a campaign scheduled for Jan. 2004. Cassini will measure the solar wind approaching Saturn continuously from 9 Jan. - 6 Feb., but not closer to Saturn due to competing spacecraft orientation constraints. The only system capable of imaging Saturn's aurora in early 2004 will be HST. In this community DD proposal we request the minimum HST time needed to support the Cassini mission during the solar wind campaign with UV images of Saturn's aurora. Saturn's magnetosphere is intermediate between the "closed" Jovian case with large internal sources of plasma and the Earth's magnetosphere which is open to solar wind interactions. Saturn's aurora has been shown to exhibit large temporal variations in brightness and morphology from Voyager and HST observations. Changes of auroral emitted power exceeding one order of magnitude, dawn brightenings, and latitudinal motions of the main oval have all been observed. Lacking knowledge of solar wind conditions near Saturn, it has not been possible to determine its role in Saturn's auroral processes, nor the mechanisms controlling the auroral precipitation. During Cassini's upcoming approach to Saturn there will be a unique opportunity to answer these questions. We propose to image one complete rotation of Saturn to determine the corotational and longitudinal dependences of the auroral activity. We will then image the active sector of Saturn once every two days for a total coverage of 26 days during the Cassini campaign to measure the upstream solar wind parameters. This is the minimum coverage needed to ensure observations of the aurora under solar wind pressure variations of more than a factor of two, based on the solar wind pressure variations measured by Voyager 2 near Saturn on the declining phase of solar activity. The team of proposers has carried out a similar coordinated observing campaign of Jupiter during the Cassini flyby, resulting in a set of papers and HST images on the cover of Nature on 28 February 2002. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910048402&hterms=fast+memory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfast%2Bmemory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910048402&hterms=fast+memory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dfast%2Bmemory">Wave-particle interactions on the FAST satellite</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Temerin, M. A.; Carlson, C. W.; Cattell, C. A.; Ergun, R. E.; Mcfadden, J. P. 1990-01-01 NASA's Fast Auroral Snapshot, or 'FAST' satellite, scheduled for launch in 1993, will investigate the plasma physics of the low altitude auroral zone from a 3500-km apogee polar orbit. FAST will give attention to wave, double-layer, and soliton production processes due to electrons and ions, as well as to wave-wave interactions, and the acceleration of electrons and ions by waves and electric fields. FAST will employ an intelligent data-handling system capacle of data acquisition at rates of up to 1 Mb/sec, in addition to a 1-Gbit solid-state memory. The data need be gathered for only a few minutes during passes through the auroral zone, since the most interesting auroral phenomena occur in such narrow regions as auroral arcs, electrostatic shocks, and superthermal electron bursts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhDT........40R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhDT........40R">Upwelling to Outflowing Oxygen Ions at Auroral Latitudes during Quiet Times: Exploiting a New Satellite Database</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Redmon, Robert J. The mechanisms by which thermal O+ escapes from the top of the ionosphere and into the magnetosphere are not fully understood even with 30 years of active research. This thesis introduces a new database, builds a simulation framework around a thermospheric model and exploits these tools to gain new insights into the study of O+ ion outflows. A dynamic auroral boundary identification system is developed using Defense Meteorological Satellite Program (DMSP) spacecraft observations at 850 km to build a database characterizing the oxygen source region. This database resolves the ambiguity of the expansion and contraction of the auroral zone. Mining this new dataset, new understanding is revealed. We describe the statistical trajectory of the cleft ion fountain return flows over the polar cap as a function of activity and the orientation of the interplanetary magnetic field y-component. A substantial peak in upward moving O+ in the morning hours is discovered. Using published high altitude data we demonstrate that between 850 and 6000 km altitude, O+ is energized predominantly through transverse heating; and acceleration in this altitude region is relatively more important in the cusp than at midnight. We compare data with a thermospheric model to study the effects of solar irradiance, electron precipitation and neutral wind on the distribution of upward O+ at auroral latitudes. EUV irradiance is shown to play a dominant role in establishing a dawn-focused source population of upwelling O+ that is responsible for a pre-noon feature in escaping O+ fluxes. This feature has been corroborated by observations on platforms including the Dynamics Explorer 1 (DE-1), Polar, and Fast Auroral Snapshot SnapshoT (FAST) spacecraft. During quiet times our analysis shows that the neutral wind is more important than electron precipitation in establishing the dayside O+ upwelling distribution. Electron precipitation is found to play a relatively modest role in controlling dayside, and a critical role in controlling nightside, upwelling O+. This thesis provides a new database, and insights into the study of oxygen ion outflows during quiet times. These results and tools will be essential for researchers working on topics involving magnetosphere-ionosphere interactions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.9705Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.9705Z">Latitude Dependence of Low-Altitude O+ Ion Upflow: Statistical Results From FAST Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhao, K.; Chen, K. W.; Jiang, Y.; Chen, W. J.; Huang, L. F.; Fu, S. 2017-09-01 We introduce a statistical model to explain the latitudinal dependence of the occurrence rate and energy flux of the ionospheric escaping ions, taking advantage of advances in the spatial coverage and accuracy of FAST observations. We use a weighted piecewise Gaussian function to fit the dependence, because two probability peaks are located in the dayside polar cusp source region and the nightside auroral oval zone source region. The statistical results show that (1) the Gaussian Mixture Model suitably describes the dayside polar cusp upflows, and the dayside and the nightside auroral oval zone upflows. (2) The magnetic latitudes of the ionospheric upflow source regions expand toward the magnetic equator as Kp increases, from 81° magnetic latitude (MLAT) (cusp upflows) and 63° MLAT (auroral oval upflows) during quiet times to 76° MLAT and 61° MLAT, respectively. (3) The dayside polar cusp region provides only 3-5% O+ upflows among all the source regions, which include the dayside auroral oval zone, dayside polar cusp, nightside auroral oval zone, and even the polar cap. However, observations show that more than 70% of upflows occur in the auroral oval zone and that the occurrence probability increases at the altitudes of 3500-4200 km, which is considered to be the lower altitude boundary of ion beams. This observed result suggests that soft electron precipitation and transverse wave heating are the most efficient ion energization/acceleration mechanisms at the altitudes of FAST orbit, and that the parallel acceleration caused by field-aligned potential drops becomes effective above that altitude. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMED31F3463G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMED31F3463G">An Undergraduate Student Instrumentation Project (USIP) to Develop New Instrument Technology to Study the Auroral Ionosphere and Stratospheric Ozone Layer Using Ultralight Balloon Payloads</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gamblin, R.; Marrero, E.; Bering, E. A., III; Leffer, B.; Dunbar, B.; Ahmad, H.; Canales, D.; Bias, C.; Cao, J.; Pina, M.; Ehteshami, A.; Hermosillo, D.; Siddiqui, A.; Guala, D. 2014-12-01 This project is currently engaging tweleve undergraduate students in the process of developing new technology and instrumentation for use in balloon borne geospace investigations in the auroral zone. Motivation stems from advances in microelectronics and consumer electronic technology. Given the technological inovations over the past 20 years it now possible to develop new instrumentation to study the auroral ionosphere and stratospheric ozone layer using ultralight balloon payloads for less than 6lbs and $3K per payload. The UH USIP undergraduate team is currently in the process of build ten such payloads for launch using1500 gm latex weather balloons to be deployed in Houston and Fairbanks, AK as well as zero pressure balloons launched from northern Sweden. The latex balloon project will collect vertical profiles of wind speed, wind direction, temperature, electrical conductivity, ozone and odd nitrogen. This instrument payload will also profiles of pressure, electric field, and air-earth electric current. The zero pressure balloons will obtain a suite of geophysical measurements including: DC electric field, electric field and magnetic flux, optical imaging, total electron content of ionosphere via dual-channel GPS, X-ray detection, and infrared/UV spectroscopy. Students will fly payloads with different combinations of these instruments to determine which packages are successful. Data collected by these instruments will be useful in understanding the nature of electrodynamic coupling in the upper atmosphere and how the global earth system is changing. Results and best practices learned from lab tests and initial Houston test flights will be discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.2151M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.2151M">Relation of Field-Aligned Currents Measured by the Network of Iridium® Spacecraft to Solar Wind and Substorms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> McPherron, R. L.; Anderson, B. J.; Chu, Xiangning 2018-03-01 The strength of field-aligned currents coupling the magnetosphere to the ionosphere was obtained by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) using the network of Iridium® spacecraft. The distribution of current was integrated giving total current in and out of the ionosphere on the dayside and nightside of the Earth in both hemispheres. The onset of auroral zone negative bays and midlatitude positive bays corresponds to an increase in nightside upward current. The total outward current tends toward saturation with increasing solar wind driver strength. The optimum solar wind coupling function for AL index predicts 73% of the variance in nightside upward current. The dayside and nightside predictors of upward current rise to a peak at 30-45 min and decay slowly over 2.5 hr. Nightside response is delayed relative to dayside. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860007325','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860007325">Global auroral responses to magnetospheric compressions by shocks in the solar wind: Two case studies</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Craven, J. D.; Frank, L. A.; Russell, C. T.; Smith, E. J.; Lepping, R. P. 1985-01-01 The global auroral responses to shocks in the solar wind at Earth were studied. The z-component of the interplanetary magnetic field, Bz, is negative ahead and behind the first shock and positive for the second case. A sudden-commencement geomagnetic storm develops in each case, with maximum D sub st 190 nT. An immediate auroral response is detected at all longitudes around the auroral oval, in which auroral luminosities increase by a factor of 2 to 3 with the first samples after each sudden commencement. The time delay in obtaining the first sample varies with local time from approx. 1 to 18 mins. No other significant variations in the aurora are associated with the immediate response. Beginning approx. 30 mins after each sudden commencement, the aurora becomes active and displays significant variations in its luminosity and spatial distribution. For Bz 0 an intense substorm develops. A sun-aligned transpolar arc forms when Bz 0, appearing first at local midnight as a polar arc and then lengthening sunward from the auroral oval across the polar cap to noon at an average speed of approx. 1 km/sec. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12210694H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12210694H">High-Latitude Neutral Mass Density Maxima</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Huang, C. Y.; Huang, Y.; Su, Y.-J.; Huang, T.; Sutton, E. K. 2017-10-01 Recent studies have reported that thermospheric effects due to solar wind driving can be observed poleward of auroral latitudes. In these papers, the measured neutral mass density perturbations appear as narrow, localized maxima in the cusp and polar cap. They conclude that Joule heating below the spacecraft is the cause of the mass density increases, which are sometimes associated with local field-aligned current structures, but not always. In this paper we investigate neutral mass densities measured by accelerometers on the CHAllenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) spacecraft from launch until years 2010 (CHAMP) and 2012 (GRACE), approximately 10 years of observations from each satellite. We extract local maxima in neutral mass densities over the background using a smoothing window with size of one quarter of the orbit. The maxima have been analyzed for each year and also for the duration of each set of satellite observations. We show where they occur, under what solar wind conditions, and their relation to magnetic activity. The region with the highest frequency of occurrence coincides approximately with the cusp and mantle, with little direct evidence of an auroral zone source. Our conclusions agree with the "hot polar cap" observations that have been reported and studied in the past. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GMS...216..121M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GMS...216..121M">Relationship between Alfvén Wave and Quasi-Static Acceleration in Earth's Auroral Zone</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mottez, Fabrice 2016-02-01 There are two main categories of acceleration processes in the Earth's auroral zone: those based on quasi-static structures, and those based on Alfvén wave (AW). AWs play a nonnegligible role in the global energy budget of the plasma surrounding the Earth because they participate in auroral acceleration, and because auroral acceleration conveys a large portion of the energy flux across the magnetosphere. Acceleration events by double layers (DLs) and by AW have mostly been investigated separately, but many studies cited in this chapter show that they are not independent: these processes can occur simultaneously, and one process can be the cause of the other. The quasi-simultaneous occurrences of acceleration by AW and by quasi-static structures have been observed predominantly at the polar cap boundary of auroral arc systems, where often new bright arcs develop or intensify. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019845','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019845">Geostrophic adjustment in a shallow-water numerical model as it relates to thermospheric dynamics</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Larsen, M. F.; Mikkelsen, I. S. 1986-01-01 The theory of geostrophic adjustment and its application to the dynamics of the high latitude thermosphere have been discussed in previous papers based on a linearized treatment of the fluid dynamical equations. However, a linearized treatment is only valid for small Rossby numbers given by Ro = V/fL, where V is the wind speed, f is the local value of the Coriolis parameter, and L is a characteristic horizontal scale for the flow. For typical values in the auroral zone, the approximation is not reasonable for wind speeds greater than 25 m/s or so. A shallow-water (one layer) model was developed that includes the spherical geometry and full nonlinear dynamics in the momentum equations in order to isolate the effects of the nonlinearities on the adjustment process. A belt of accelerated winds between 60 deg and 70 deg latitude was used as the initial condition. The adjustment process was found to proceed as expected from the linear formulation, but that an asymmetry between the response for an eastward and westward flow results from the nonlineawr curvature (centrifugal) terms. In general, the amplitude of an eastward flowing wind will be less after adjustment than a westward wind. For instance, if the initial wind velocity is 300 m/s, the linearized theory predicts a final wind speed of 240 m/s, regardless of the flow direction. However, the nonlinear curvature terms modify the response and produce a final wind speed of only 200 m/s for an initial eastward wind and a final wind speed of almost 300 m/s for an initial westward flow direction. Also, less gravity wave energy is produced by the adjustment of the westward flow than by the adjustment of the eastward flow. The implications are that the response of the thermosphere should be significantly different on the dawn and dusk sides of the auroral oval. Larger flow velocities would be expected on the dusk side since the plasma will accelerate the flow in a westward direction in that sector. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890024143&hterms=transverse+study&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtransverse%2Bstudy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890024143&hterms=transverse+study&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dtransverse%2Bstudy">Transverse ion energization and low-frequency plasma waves in the mid-altitude auroral zone - A case study</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Peterson, W. K.; Shelley, E. G.; Boardsen, S. A.; Gurnett, D. A.; Ledley, B. G.; Sugiura, M.; Moore, T. E. 1988-01-01 Evidence of transverse ion energization at altitudes of several earth radii in the auroral zone was reexamined using several hundred hours of high-sensitivity and high-resolution plasma data obtained by the Dynamics Explorer 1 satellite. The data on particle environment encountered at midaltitudes in the auroral zone disclosed rapid variations in the values of total density, thermal structure, and composition of the plasma in the interval measured; the modes of low-frequency plasma waves also varied rapidly. It was not possible to unambiguously identify in these data particle and wave signature of local transverse ion energization; however, many intervals were found where local transverse ion heating was consistent with the observations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995JATP...57..177K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995JATP...57..177K">Double structure of ionospheric conductivity in the midnight auroral oval during a substorm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kotikov, A. L.; Shishkina, E. M.; Troshichev, O. A.; Sergienko, T. I. 1995-02-01 Measurements of precipitating particles on board Defense Meteorological Satellite Program (DMSP) F7 spacecraft are used to analyze the distribution of ionospheric conductance in the midnight auroral zone during substorms. The distribution is compared with the meridional profile of ionospheric currents calculated from magnetic data from the Kara meridional chain. Two regions of high Hall conductance are found; one of them is the traditional auroral zone, at latitudes 64-68 deg, and the other is a narrow band at latitudes 70-73 deg. The position of high conductance zones is in agreement with the location of the intense westward currents. The accelerated particle population is typical of electrons E(sub e) greater than 5 keV in the high conductance region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA44A..08G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA44A..08G">The Effect of Sub-Auroral Polarization Streams (SAPS) on Ionosphere and Thermosphere during 2015 St. Patrick's Day storm: Global Ionosphere-Thermosphere Model (GITM) Simulations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Guo, J.; Deng, Y.; Zhang, D.; Lu, Y.; Sheng, C. 2017-12-01 Sub-Auroral Polarization Streams (SAPS) are incorporated into the non-hydrostatic Global Ionosphere-Thermosphere Model (GITM), revealing the complex effects on neutral dynamics and ion-neutral coupling processes. The intense westward ion stream could enhance the neutral zonal wind within the SAPS channel. Through neutral dynamics the neutrals then divide into two streams, one turns poleward and the other turns equatorward, forming a two-cell pattern in the SAPS-changed wind. The significant Joule heating induced by SAPS also leads to traveling atmospheric disturbances (TAD) accompanied by traveling ionospheric disturbances (TID), increasing the total electron content (TEC) by 2-8 TECu in the mid-latitude ionosphere. We investigate the potential causes of the reported poleward wind surge during the St. Patrick's Day storm in 2015. It is confirmed that Coriolis force on the westward zonal wind can contribute the poleward wind during post-SAPS interval. In addition, the simulations imply that the sudden decrease of heating rate within auroral oval could result in a TAD propagating equatorward, which could also be responsible for the sudden poleward wind surge. This study highlights the complicated effects of SAPS on ion-neutral coupling and neutral dynamics. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850062284&hterms=conjunctions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dconjunctions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850062284&hterms=conjunctions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dconjunctions">Auroral zone electric fields from DE 1 and 2 at magnetic conjunctions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Weimer, D. R.; Goertz, C. K.; Gurnett, D. A.; Maynard, N. C.; Burch, J. L. 1985-01-01 Nearly simultaneous measurements of auroral zone electric fields are obtained by the Dynamics Explorer spacecraft at altitudes below 900 km and above 4,500 km during magnetic conjunctions. The measured electric fields are usually perpendicular to the magnetic field lines. The north-south meridional electric fields are projected to a common altitude by a mapping function which accounts for the convergence of the magnetic field lines. When plotted as a function of invariant latitude, graphs of the projected electric fields measured by both DE-1 and DE-2 show that the large-scale electric field is the same at both altitudes, as expected. Superimposed on the large-scale fields, however, are small-scale features with wavelengths less than 100 km which are larger in magnitude at the higher altitude. Fourier transforms of the electric fields show that the magnitudes depend on wavelength. Outside of the auroral zone the electric field spectrums are nearly identical. But within the auroral zone the high and low altitude electric fields have a ratio which increases with the reciprocal of the wavelength. The small-scale electric field variations are associated with field-aligned currents. These currents are measured with both a plasma instrument and magnetometer on DE-1. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AnGeo..31..263V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AnGeo..31..263V">Variability of ionospheric TEC during solar and geomagnetic minima (2008 and 2009): external high speed stream drivers</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Verkhoglyadova, O. P.; Tsurutani, B. T.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Runge, T. 2013-02-01 We study solar wind-ionosphere coupling through the late declining phase/solar minimum and geomagnetic minimum phases during the last solar cycle (SC23) - 2008 and 2009. This interval was characterized by sequences of high-speed solar wind streams (HSSs). The concomitant geomagnetic response was moderate geomagnetic storms and high-intensity, long-duration continuous auroral activity (HILDCAA) events. The JPL Global Ionospheric Map (GIM) software and the GPS total electron content (TEC) database were used to calculate the vertical TEC (VTEC) and estimate daily averaged values in separate latitude and local time ranges. Our results show distinct low- and mid-latitude VTEC responses to HSSs during this interval, with the low-latitude daytime daily averaged values increasing by up to 33 TECU (annual average of ~20 TECU) near local noon (12:00 to 14:00 LT) in 2008. In 2009 during the minimum geomagnetic activity (MGA) interval, the response to HSSs was a maximum of ~30 TECU increases with a slightly lower average value than in 2008. There was a weak nighttime ionospheric response to the HSSs. A well-studied solar cycle declining phase interval, 10-22 October 2003, was analyzed for comparative purposes, with daytime low-latitude VTEC peak values of up to ~58 TECU (event average of ~55 TECU). The ionospheric VTEC changes during 2008-2009 were similar but ~60% less intense on average. There is an evidence of correlations of filtered daily averaged VTEC data with Ap index and solar wind speed. We use the infrared NO and CO2 emission data obtained with SABER on TIMED as a proxy for the radiation balance of the thermosphere. It is shown that infrared emissions increase during HSS events possibly due to increased energy input into the auroral region associated with HILDCAAs. The 2008-2009 HSS intervals were ~85% less intense than the 2003 early declining phase event, with annual averages of daily infrared NO emission power of ~ 3.3 × 1010 W and 2.7 × 1010 W in 2008 and 2009, respectively. The roles of disturbance dynamos caused by high-latitude winds (due to particle precipitation and Joule heating in the auroral zones) and of prompt penetrating electric fields (PPEFs) in the solar wind-ionosphere coupling during these intervals are discussed. A correlation between geoeffective interplanetary electric field components and HSS intervals is shown. Both PPEF and disturbance dynamo mechanisms could play important roles in solar wind-ionosphere coupling during prolonged (up to days) external driving within HILDCAA intervals. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750057144&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2526%25231041','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750057144&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2526%25231041">Magnetospheric and auroral plasmas - A short survey of progress</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Frank, L. A. 1975-01-01 Important milestones in our researches of auroral and magnetospheric plasmas for the past quadrennium 1971-1975 are reviewed. Many exciting findings, including those of the polar cusp, the polar wind, the explosive disruptions of the magnetotail, the interactions of hot plasmas with the plasmapause, the auroral field-aligned currents, and the striking inverted V electron precipitation events, were reported during this period. Solutions to major questions concerning the origins and acceleration of these plasmas appear possible in the near future. A comprehensive bibliography of current research is appended to this brief survey of auroral and magnetospheric plasmas. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950057064&hterms=recurrence+sequences&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Drecurrence%2Bsequences','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950057064&hterms=recurrence+sequences&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Drecurrence%2Bsequences">Cusp/cleft auroral activity in relation to solar wind dynamic pressure, interplanetary magnetic field B(sub z) and B(sub y)</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sandholt, P. E.; Farrugia, C. J.; Burlaga, L. F.; Holtet, J. A.; Moen, J.; Lybekk, B.; Jacobsen, B.; Opsvik, D.; Egeland, A.; Lepping, R. 1994-01-01 Continuous optical observations of cusp/cleft auroral activities within approximately equal to 09-15 MLT and 70-76 deg magnetic latitude are studied in relation to changes in solar wind dynamic pressure and interplanetary magnetic field (IMF) variability. The observed latitudinal movements of the cusp/cleft aurora in response to IMF B(sub z) changes may be explained as an effect of a variable magnetic field intensity in the outer dayside magnetosphere associated with the changing intensity of region 1 field-aligned currents and associated closure currents. Ground magnetic signatures related to such currents were observed in the present case (January 10, 1993). Strong, isolated enhancements in solar wind dynamic pressure (Delta p/p is greater than or equal to 0.5) gave rise to equatorward shifts of the cusp/cleft aurora, characteristic auroral transients, and distinct ground magnetic signatures of enhanced convection at cleft latitudes. A sequence of auroral events of approximately equal to 5-10 min recurrence time, moving eastward along the poleward boundary of the persistent cusp/cleft aurora in the approximately equal to 10-14 MLT sector, during negative IMF B(sub z) and B(sub y) conditions, were found to be correlated with brief pulses in solar wind dynamic pressure (0.1 is less than Delta p/p is less than 0.5). Simultaneous photometer observations from Ny Alesund, Svalbard, and Danmarkshavn, Greenland, show that the events often appeared on the prenoon side (approximately equal to 10-12 MLT), before moving into the postnoon sector in the case we study here, when IMF B(sub y) is less than 0. In other cases, similar auroral event sequences have been observed to move westward in the prenoon sector, during intervals of positive B(sub y). Thus a strong prenoon/postnoon asymmetry of event occurence and motion pattern related to the IMF B(sub y) polarity is observed. We find that this category of auroral event sequence is stimulated bursts of electron precipitation that originate from magnetosheath plasma that has accessed that dayside magnetosphere in the noon or near-noon sector, possibly at high latitudes, partly governed by the IMF orientation as well as by solar wind dynamic pressure pulses. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active">3</li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active">4</li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AAS...211.2304M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AAS...211.2304M">The Aurora, Magnetosphere, and the IGY</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> McKim Malville, J. 2007-12-01 This retrospective of auroral research during the IGY will be from the perspective of the auroral observers in the Antarctic from 1956-58. The IGY served as a watershed divide in our understanding of auroral physics. Prior to the IGY the role of "solar corpuscular radiation” in exciting auroral radiation was the pre-eminent research question. The mechanisms for the acceleration of solar protons and electrons had not been resolved, nor had the role of plasma instabilities been envisioned. The spectroscopic research program during the IGY was dominated by the work of Aden Meinel and Joseph W. Chamberlain at Yerkes Observatory. The dynamics of precipitating solar protons into a dilute gas was a major research focus. The changes brought about by the discoveries of the radiation belts, the solar wind, and the magnetosphere resulted in a remarkable transformation and a paradigm shift in our understanding of the physics of the aurora. Antarctic observations during the IGY revealed the auroral oval, which is a signature of radiation belts distorted by the solar wind. High auroral rays could be explained by pitch angle distributions of trapped electrons. Sudden accelerations of electrons, resulting in red lower borders of aurora deep in the atmosphere, revealed the serious deficiencies of available theory. Whistlers, first detected in the Antarctic at Ellsworth Station in 1957, proved to be valuable probes of the magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26074636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26074636">Dynamic auroral storms on Saturn as observed by the Hubble Space Telescope.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Nichols, J D; Badman, S V; Baines, K H; Brown, R H; Bunce, E J; Clarke, J T; Cowley, S W H; Crary, F J; Dougherty, M K; Gérard, J-C; Grocott, A; Grodent, D; Kurth, W S; Melin, H; Mitchell, D G; Pryor, W R; Stallard, T S 2014-05-28 We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330% rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4459195','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4459195">Dynamic auroral storms on Saturn as observed by the Hubble Space Telescope</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Nichols, J D; Badman, S V; Baines, K H; Brown, R H; Bunce, E J; Clarke, J T; Cowley, S W H; Crary, F J; Dougherty, M K; Gérard, J-C; Grocott, A; Grodent, D; Kurth, W S; Melin, H; Mitchell, D G; Pryor, W R; Stallard, T S 2014-01-01 We present observations of significant dynamics within two UV auroral storms observed on Saturn using the Hubble Space Telescope in April/May 2013. Specifically, we discuss bursts of auroral emission observed at the poleward boundary of a solar wind-induced auroral storm, propagating at ∼330% rigid corotation from near ∼01 h LT toward ∼08 h LT. We suggest that these are indicative of ongoing, bursty reconnection of lobe flux in the magnetotail, providing strong evidence that Saturn's auroral storms are caused by large-scale flux closure. We also discuss the later evolution of a similar storm and show that the emission maps to the trailing region of an energetic neutral atom enhancement. We thus identify the auroral form with the upward field-aligned continuity currents flowing into the associated partial ring current. PMID:26074636 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20150008886&hterms=storms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dstorms','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20150008886&hterms=storms&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dstorms">Forcing of the Coupled Ionosphere-Thermosphere (IT) System During Magnetic Storms</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Huang, Cheryl; Huang, Yanshi; Su, Yi-Jiun; Sutton, Eric; Hairston, Marc; Coley, W. Robin; Doornbos, Eelco; Zhang, Yongliang 2014-01-01 Poynting flux shows peaks around auroral zone AND inside polar cap. Energy enters IT system at all local times in polar cap. Track-integrated flux at DMSP often peaks at polar latitudes- probably due to increased area of polar cap during storm main phases. center dot lon temperatures at DMSP show large increases in polar region at all local times; cusp and auroral zones do not show distinctively high Ti. center dot I on temperatures in the polar cap are higher than in the auroral zones during quiet times. center dot Neutral densities at GRACE and GOCE show maxima at polar latitudes without clear auroral signatures. Response is fast, minutes from onset to density peaks. center dot GUVI observations of O/N2 ratio during storms show similar response as direct measurements of ion and neutral densities, i.e. high temperatures in polar cap during prestorm quiet period, heating proceeding from polar cap to lower latitudes during storm main phase. center dot Discrepancy between maps of Poynting flux and of ion temperatures/neutral densities suggests that connection between Poynting flux and Joule heating is not simple. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMIN34A..05J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMIN34A..05J">Data Acquisition System for Russian Arctic Magnetometer Network</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Janzhura, A.; Troshichev, O. A.; Takahashi, K. 2010-12-01 Monitoring of magnetic activity in the auroral zone is very essential for space weather problem. The big part of northern auroral zone lies in the Russian sector of Arctica. The Russian auroral zone stations are located far from the proper infrastructure and communications, and getting the data from the stations is complicated and nontrivial task. To resolve this problem a new acquisition system for magnetometers was implemented and developed in last few years, with the magnetic data transmission in real time that is important for many forecasting purpose. The system, based on microprocessor modules, is very reliable in hush climatic conditions. The information from the magnetic sensors transmits to AARI data center by satellite communication system and is presented at AARI web pages. This equipment upgrading of Russian polar magnetometer network is supported by the international RapidMag program. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850051361&hterms=environnement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Denvironnement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850051361&hterms=environnement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Denvironnement">Universal time dependence of nighttime F region densities at high latitudes</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> De La Beaujardiere, O.; Wickwar, V. B.; Caudal, G.; Holt, J. M.; Craven, J. D.; Frank, L. A.; Brace, L. H. 1985-01-01 Coincident auroral-zone experiments using three incoherent-scatter radars at widely spaced longitudes are reported. The observational results demonstrate that, during the night, the F layer electron density is strongly dependent on the longitude of the observing site. Ionization patches were observed in the nighttime F region from the Chatanika and EISCAT radars, while densities observed from the Millstone radar were substantially smaller. The electron density within these maxima is larger at EISCAT than at Chatanika. When observed in the midnight sector auroral zone, these densities had a peak density at a high altitude of 360-475 km. The density was maximum when EISCAT was in the midnight sector and minimum when Millstone was in the midnight sector. A minimum in insolation in the auroral zone occurs at the UT when Millstone is in the midnight sector. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMSA21B0078D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMSA21B0078D">Examing the Effects of Different IMF, F10.7, and Auroral Inputs on the Thermospheric Neutral Winds</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Deng, Y.; Ridley, A. J. 2003-12-01 To obtain a better understanding of how the magnetosphere effects the global thermospheric and ionospheric structure, we conduct some numerical experiments using the University of Michigan's Global Ionosphere-Thermosphere Model (GITM). We have run GITM to roughly steady-state using different strengths of the high-latitude electric potential pattern, F10.7, and auroral inputs to determine how these effect the temporal history and stead-state of the thermospheric neutral winds. Our model reproduces the well known fact that the neutral winds are strongly driven by the ion convection above approximately 300 km, and that the ramp-up time is very dependent upon the altitude. We show quantitative results of the ramp-up times and maximum neutral wind speeds for the different driving conditions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720055073&hterms=time+zone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtime%2Bzone','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720055073&hterms=time+zone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtime%2Bzone">Local-time survey of plasma at low altitudes over the auroral zones.</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Frank, L. A.; Ackerson, K. L. 1972-01-01 Local-time survey of the low-energy proton and electron intensities precipitated into the earth's atmosphere over the auroral zones during periods of magnetic quiescence. This survey was constructed by selecting a typical individual satellite crossing of this region in each of eight local-time sectors from a large library of similar observations with the polar-orbiting satellite Injun 5. The trapping boundary for more-energetic electron intensities, E greater than 45 keV, was found to be a 'natural coordinate' for delineating the boundary between the two major types of lower-energy, 50 less than or equal to E less than or equal to 15,000 eV, electron precipitation commonly observed over the auroral zones at low altitudes. Poleward of this trapping boundary inverted 'V' electron precipitation bands are observed in all local-time sectors. These inverted 'V' electron bands in the evening and midnight sectors are typically more energetic and have greater latitudinal widths than their counterparts in the noon and morning sectors. In general, the main contributors to the electron energy influx into the earth's atmosphere over the auroral zones are the electron inverted 'V' precipitation poleward of the trapping boundary in late evening, the plasma-sheet electron intensities equatorward of this boundary in early morning, and both of these precipitation events near local midnight. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110011745','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110011745">V and V Efforts of Auroral Precipitation Models: Preliminary Results</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Zheng, Yihua; Kuznetsova, Masha; Rastaetter, Lutz; Hesse, Michael 2011-01-01 Auroral precipitation models have been valuable both in terms of space weather applications and space science research. Yet very limited testing has been performed regarding model performance. A variety of auroral models are available, including empirical models that are parameterized by geomagnetic indices or upstream solar wind conditions, now casting models that are based on satellite observations, or those derived from physics-based, coupled global models. In this presentation, we will show our preliminary results regarding V&V efforts of some of the models. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750010749','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750010749">Magnetospheric and auroral plasmas: A short survey of progress, 1971 - 1975</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Frank, L. A. 1975-01-01 Milestones in researches of auroral and magnetospheric plasmas for the past quadrennium 1971 - 1975 are reviewed. Findings, including those of the polar cusp, the polar wind, the explosive disruptions of the magnetotail, the interactions of hot plasmas with the plasmapause, the auroral field-aligned currents, and the striking 'inverted-V' electron precipitation events, are reported. Solutions to major questions concerning the origins and acceleration of these plasmas are discussed. A comprehensive bibliography of current research is included. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850067082&hterms=Biddle&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBiddle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850067082&hterms=Biddle&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBiddle">Evidence for ion heat flux in the light ion polar wind</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Biddle, A. P.; Moore, T. E.; Chappell, C. R. 1985-01-01 Cold flowing hydrogen and helium ions have been observed using the retarding ion mass spectrometer on board the Dynamics Explorer 1 spacecraft in the dayside magnetosphere at subauroral latitudes. The ions show a marked flux asymmetry with respect to the relative wind direction. The observed data are fitted by a model of drifting Maxwellian distributions perturbed by a first order-Spritzer-Haerm heat flux distribution function. It is shown that both ion species are supersonic just equatorward of the auroral zone at L = 14, and the shape of asymmetry and direction of the asymmetry are consistent with the presence of an upward heat flux. At L = 6, both species evolve smoothly into warmer subsonic upward flows with downward heat fluxes. In the case of subsonic flows the downward heat flux implies a significant heat source at higher altitudes. Spin curves of the spectrometer count rate versus the spin phase angle are provided. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860038155&hterms=destiny&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddestiny','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860038155&hterms=destiny&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddestiny">Destiny of earthward streaming plasma in the plasmasheet boundary layer</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Green, J. L.; Horwitz, J. L. 1986-01-01 The dynamics of the earth's magnetotail have been investigated, and it has become clear that the plasmasheet boundary layer field lines map into the Region I Field-Aligned Currents (FAC) of the auroral zone. It is pointed out that the role of earthward streaming ions in the plasmasheet boundary layer may be of fundamental importance in the understanding of magnetotail dynamics, auroral zone physics, and especially for ionospheric-magnetospheric interactions. The present paper has the objective to evaluate propagation characteristics for the earthward streaming ions observed in the plasmasheet boundary layer. An investigation is conducted of the propagation characteristics of protons in the plasmasheet boundary layer using independent single particle dynamics, and conclusions are discussed. The density of earthward streaming ions found in the plasmasheet boundary layer should include the ring current as well as the auroral zone precipitaiton and inner plasmasheet regions of the magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5126218-morphology-auroral-zone-radio-wave-scintillation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5126218-morphology-auroral-zone-radio-wave-scintillation">Morphology of auroral zone radio wave scintillation</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Rino, C.L.; Matthews, S.J. 1980-08-01 This paper describes the morphology of midnight sector and morning sector auroral zone scintillation observations made over a two-year period using the Wideband satelite, which is in a sun-synchronous, low-altitude orbit. No definitive seasonal variation was found. The nighttime data showed the highest scintillation ocurrence levels, but significant amounts of morning scintillation were observed. For the most part the scintillation activity followed the general pattern of local magnetic activity. The most prominent feature in the nightime data is a localized amplitude and phase scintillation enhancement at the point where the propagation vector lies within an L shell. A geometrical effectmore » due to a dynamic slab of sheetlike structures in the F region is hypothesized as the source of his enhancement. The data have been sorted by magnetic activity, proximity to local midnight, and season. The general features of the data are in agreement with the accepted morphology of auroral zone scintillation.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.3637C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.3637C">The Association of High-Latitude Dayside Aurora With NBZ Field-Aligned Currents</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Carter, J. A.; Milan, S. E.; Fogg, A. R.; Paxton, L. J.; Anderson, B. J. 2018-05-01 The relationship between auroral emissions in the polar ionosphere and the large-scale flow of current within the Earth's magnetosphere has yet to be comprehensively established. Under northward interplanetary magnetic field (IMF) conditions, magnetic reconnection occurs at the high-latitude magnetopause, exciting two reverse lobe convection cells in the dayside polar ionosphere and allowing ingress of solar wind plasma to form an auroral "cusp spot" by direct impact on the atmosphere. It has been hypothesized that a second class of NBZ auroras, High-latitude Dayside Aurora, are produced by upward field-aligned currents associated with lobe convection. Here we present data from the Special Sensor Ultraviolet Spectrographic Imager instrument and from the Active Magnetosphere and Planetary Electrodynamics Response Experiment, from January 2010 to September 2013, in a large statistical study. We reveal a northward IMF auroral phenomenon that is located adjacent to the cusp spot and that is colocated with a region of upward electrical current in the clockwise-rotating lobe cell. The emission only occurs in the sunlit summer hemisphere, demonstrating the influence of the conductance of the ionosphere on current closure. In addition, fast solar wind speed is required for this emission to be bright. The results show that dayside auroral emission is produced by IMF-magnetosphere electrodynamic coupling, as well as by direct impact of the atmosphere by the solar wind, confirming the association of High-latitude Dayside Aurora with NBZ currents. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.9652R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.9652R">Comparison of solar wind driving of the aurora in the two hemispheres due to the solar wind dynamo</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Reistad, Jone Peter; Østgaard, Nikolai; Magnus Laundal, Karl; Haaland, Stein; Tenfjord, Paul; Oksavik, Kjellmar 2014-05-01 Event studies of simultaneous global imaging of the aurora in both hemispheres have suggested that an asymmetry of the solar wind driving between the two hemispheres could explain observations of non-conjugate aurora during specific driving conditions. North-South asymmetries in energy transfer from the solar wind across the magnetopause is believed to depend upon the dipole tilt angle and the x-component of the interplanetary magnetic field (IMF). Both negative tilt (winter North) and negative IMF Bx is expected to enhance the efficiency of the solar wind dynamo in the Northern Hemisphere. By the same token, positive tilt and IMF Bx is expected to enhance the solar wind dynamo efficiency in the Southern Hemisphere. We show a statistical study of the auroral response from both hemispheres using global imaging where we compare results during both favourable and not favourable conditions in each hemisphere. By this study we will address the question of general impact on auroral hemispheric asymmetries by this mechanism - the asymmetric solar wind dynamo. We use data from the Wideband Imaging Camera on the IMAGE spacecraft which during its lifetime from 2000-2005 covered both hemispheres. To ease comparison of the two hemispheres, seasonal differences in auroral brightness is removed as far as data coverage allows by only using events having small dipole tilt angles. Hence, the IMF Bx is expected to be the controlling parameter for the hemispheric preference of strongest solar wind dynamo efficiency in our dataset. Preliminary statistical results indicate the expected opposite behaviour in the two hemispheres, however, the effect is believed to be weak. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT.......113K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT.......113K">A search for thermospheric composition perturbations due to vertical winds</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Krynicki, Matthew P. The thermosphere is generally in hydrostatic equilibrium, with winds blowing horizontally along stratified constant-pressure surfaces, driven by the dayside-to-nightside pressure gradient. A marked change in this paradigm resulted after Spencer et al. [1976] reported vertical wind measurements of 80 m·s-1 from analyses of AE-C satellite data. It is now established that the thermosphere routinely supports large-magnitude (˜30-150 m·s-1) vertical winds at auroral latitudes. These vertical winds represent significant departure from hydrostatic and diffusive equilibrium, altering locally---and potentially globally---the thermosphere's and ionosphere's composition, chemistry, thermodynamics and energy budget. Because of their localized nature, large-magnitude vertical wind effects are not entirely known. This thesis presents ground-based Fabry-Perot Spectrometer OI(630.0)-nm observations of upper-thermospheric vertical winds obtained at Inuvik, NT, Canada and Poker Flat, AK. The wind measurements are compared with vertical displacement estimates at ˜104 km2 horizontal spatial scales determined from a new modification to the electron transport code of Lummerzheim and Lilensten [1994] as applied to FUV-wavelength observations by POLAR spacecraft's Ultraviolet Imager [Torr et al. , 1995]. The modification, referred to as the column shift, simulates vertical wind effects such as neutral transport and disruption of diffusive equilibrium by vertically displacing the Hedin [1991] MSIS-90 [O2]/[N2] and [O]/([N2]+[O2]) mixing ratios and subsequently redistributing the O, O2, and N 2 densities used in the transport code. Column shift estimates are inferred from comparisons of UVI OI(135.6)-nm auroral observations to their corresponding modeled emission. The modeled OI(135.6)-nm brightness is determined from the modeled thermospheric response to electron precipitation and estimations of the energy flux and characteristic energy of the precipitation, which are inferred from UVI-observed Lyman-Birge-Hopfield N2 emissions in two wavelength ranges. Two-dimensional column shift maps identify the spatial morphology of thermospheric composition perturbations associated with auroral forms relative to the model thermosphere. Case-study examples and statistical analyses of the column shift data sets indicate that column shifts can be attributed to vertical winds. Unanticipated limitations associated with modeling of the OI(135.6)-nm auroral emission make absolute column shift estimates indeterminate. Insufficient knowledge of thermospheric air-parcel time histories hinders interpretations of point-to-point time series comparisons between column shifts and vertical winds. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990113190&hterms=remote+viewing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dremote%2Bviewing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990113190&hterms=remote+viewing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dremote%2Bviewing">Global Auroral Remote Sensing Using GGS UVI Images</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Germany, G. A.; Parks, G. K.; Brittnacher, M. J.; Spann, J. F., Jr.; Cumnock, J.; Lummerzheim, D. 1997-01-01 The GGS POLAR satellite, with an apogee distance of 9 Earth radii, provides an excellent platform for extended viewing of the northern auroral zone. Global FUV auroral images from the Ultraviolet Imager onboard the POLAR satellite can be used as quantitative remote diagnostics of the auroral regions, yielding estimates of incident energy characteristics, compositional changes, and other higher order data products. In particular, images of long and short wavelength Earth Far Ultraviolet (FUV) Lyman-Birge-Hopfield (LBH) emissions can be modeled to obtain functions of energy flux and average energy that are basically insensitive to changes in seasonal and solar activity changes. The determination of maps of incident auroral energy characteristics is demonstrated here and compared with in situ measurements. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20100032909&hterms=lime&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dlime','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20100032909&hterms=lime&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dlime">Saturation of the Electric Field Transmitted to the Magnetosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A. 2010-01-01 We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6019565-sounding-rocket-study-auroral-electron-precipitation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6019565-sounding-rocket-study-auroral-electron-precipitation">Sounding rocket study of auroral electron precipitation</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> McFadden, J.P. 1985-01-01 Measurement of energetic electrons in the auroral zone have proved to be one of the most useful tools in investigating the phenomena of auroral arc formation. This dissertation presents a detailed analysis of the electron data from two sounding rocket campaigns and interprets the measurements in terms of existing auroral models. The Polar Cusp campaign consisted of a single rocket launched from Cape Parry, Canada into the afternoon auroral zone at 1:31:13 UT on January 21, 1982. The results include the measurement of a narrow, magnetic field aligned electron flux at the edge of an arc. This electron precipitation wasmore » found to have a remarkably constant 1.2 eV temperature perpendicular to the magnetic field over a 200 to 900 eV energy range. The payload also made simultaneous measurements of both energetic electrons and 3-MHz plasma waves in an auroral arc. Analysis has shown that the waves are propagating in the upper hybrid band and should be generated by a positive slope in the parallel electron distribution. A correlation was found between the 3-MHz waves and small positive slopes in the parallel electron distribution but experimental uncertainties in the electron measurement were large enough to influence the analysis. The BIDARCA campaign consisted of two sounding rockets launched from Poker Flat and Fort Yukon, Alaska at 9:09:00 UT and 9:10:40 UT on February 7, 1984.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM21D..03N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM21D..03N">OVATION Prime -2013: Solar Wind Driven Precipitation Model Extended to Higher Geomagnetic Activity Levels (Invited)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Newell, P. T.; Liou, K.; Zhang, Y.; Paxton, L.; Sotirelis, T.; Mitchell, E. J. 2013-12-01 OVATION Prime is an auroral precipitation model parameterized by solar wind driving. Distinguishing features of the model include an optimized solar wind-magnetosphere coupling function (dΦMP/dt) which predicts auroral power far better than Kp or other traditional parameters, the separation of aurora into categories (diffuse aurora, monoenergetic, broadband, and ion), the inclusion of seasonal variations, and separate parameter fits for each MLATxMLT bin, thus permitting each type of aurora and each location to have differing responses to season and solar wind input (as indeed they do). We here introduce OVATION Prime-2013, an upgrade to the 2008 version currently widely available. The most notable advantage of OP-2013 is that it uses UV images from the GUVI instrument on the satellite TIMED for high disturbance levels (dΦMP/dt > 12,000 (nT2/3 (km/s)4/3 which roughly corresponds to Kp = 5+ or 6-). The range of validity is thought to be about 0 < dΦMP/dt = 30000 (say Kp = 8 or 8+). Other upgrades include a reduced susceptibility to salt and pepper noise, and smoother interpolation across the postmidnight data gap. We will also provide a comparison of the advantages and disadvantages of other current precipitation models, especially OVATION-SuperMAG, which produces particularly good estimates for total auroral power, at the expense of working best on an historical basis. OVATION Prime-2013, for high solar wind driving, as TIMED GUVI data takes over from DMSP </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active">4</li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active">5</li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950057077&hterms=ev&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dev','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950057077&hterms=ev&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dev">Statistical survey of pitch angle distributions in core (0-50 eV) ions from Dynamics Explorer 1: Outflow in the auroral zone, polar cap, and cusp</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Giles, B. L.; Chappell, C. R.; Moore, T. E.; Comfort, R. H.; Waite, J. H., Jr. 1994-01-01 Core (0-50 eV) ion pitch angle measurements from the retarding ion mass spectrometer on Dynamics Explorer 1 are examined with respect to magnetic disturbance, invariant latitude, magnetic local time, and altitude for ions H(+), He(+), O(+), M/Z = 2 (D(+) or He(++)), and O(++). Included are outflow events in the auroral zone, polar cap, and cusp, separated into altitude regions below and above 3 R(sub E). In addition to the customary division into beam, conic, and upwelling distributions, the high-latitude observations fall into three categories corresponding to ion bulk speeds that are (1) less than, (2) comparable to, or (3) faster than that of the spacecraft. This separation, along with the altitude partition, serves to identify conditions under which ionospheric source ions are gravita- tionally bound and when they are more energetic and able to escape to the outer magnetosphere. Features of the cleft ion fountain inferred from single event studies are clearly identifiable in the statistical results. In addition, it is found that the dayside pre-noon cleft is a dayside afternoon cleft, or auroral zone, becomes an additional source for increased activity. The auroral oval as a whole appears to be a steady source of escape velocity H(+), a steady source of escape velocity He(+) ions for the dusk sector, and a source of escape velocity heavy ions for dusk local times primarily during increased activity. The polar cap above the auroral zone is a consistent source of low-energy ions, although only the lighter mass particles appear to have sufficient velocity, on average, to escape to higher altitudes. The observations support two concepts for outflow: (1) The cleft ion fountain consists of ionospheric plasma of 1-20 eV energy streaming upward into the magnetosphere where high-latitude convection electric fields cause poleward dispersion. (2) The auroral ion fountain involves field-aligned beams which flow out along auroral latitude field lines; and, in addition, for late afternoon local times, they experience additional acceleration such that the ion energy distribution tends to exceed the detection range of the instrument (greater than 50-60 eV). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMSM34A..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMSM34A..03M">Coordinated measurements of auroral processes at Saturn from the Cassini spacecraft and HST</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mitchell, D. G.; Kurth, W. S.; Hospodarsky, G. B.; Gurnett, D. A.; Krupp, N.; Saur, J.; Mauk, B. A.; Carbary, J. F.; Krimigis, S. M.; Brandt, P. C.; Dougherty, M. K.; Clarke, J. T.; Nichols, J. D.; Gerard, J.; Grodent, D.; Pryor, W. R.; Bunce, E. J.; Crary, F. J. 2008-12-01 One of the primary Cassini mission objectives at Saturn is to characterize Saturn's aurora-its spatial morphology, associated particle energization, radio wave generation, and magnetospheric currents, relationship with solar wind pressure and magnetic field, and its large scale mapping to the magnetosphere. By design, the Cassini orbital tour included high inclination and low periapsis orbits late in the prime mission specifically to address many of these topics. In this presentation, we will provide a snapshot of the current state of our investigation into the relationship between magnetospheric measurements of particles and fields, and the aurora. For in situ data, we will show measurements of upward traveling light ion conics (~30 keV to 200 keV), often accompanied by electron beams (<20 keV to ~1 MeV) and enhanced broadband noise (10 Hz to a few kHz), throughout the outer magnetosphere on field lines that nominally map from well into the polar cap (dipole L > 50) to well into the closed field region (dipole L < 10). Sometimes the particle phenomena and the broadband noise occur in pulses of roughly five-minute duration, separated by tens of minutes. At other times they are relatively steady over an hour or more. Magnetic signatures associated with some of the pulsed events are consistent with field aligned current structures. Correlative observations of solar wind (Cassini) and aurora (HST) have established a strong relationship between solar wind pressure and auroral activity (brightness) (Crary et al., Nature, 2005; Clarke et al., JGR, 2008). A similar correspondence between bright auroral arcs and ring current ion acceleration will be shown here. So while some auroral forms seem to be associated with the open/closed field boundary (i.e. in the cusp-Bunce et al., JGR, 2008), we also demonstrate that under some magnetospheric conditions for which protons and oxygen ions are accelerated once per Saturn magnetosphere rotation at a preferred local time between midnight and dawn, simultaneous auroral observations by the HST reveal a close correlation between these dynamical magnetospheric events and dawn-side transient auroral brightenings. Likewise, many of the recurrent energetic neutral atom enhancements coincide closely with bursts of Saturn kilometric radiation, again suggesting a linkage with high latitude auroral processes. Finally, we will show some intriguing results of auroral movie sequences from the Cassini UVIS instrument with corresponding ring current movies from the Magnetospheric Imaging Instrument Ion and Neutral Camera (MIMI/INCA). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880038015&hterms=Geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DGeomagnetic%2Breversal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880038015&hterms=Geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DGeomagnetic%2Breversal">Thermospheric dynamics during November 21-22, 1981 - Dynamics Explorer measurements and thermospheric general circulation model predictions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Roble, R. G.; Killeen, T. L.; Spencer, N. W.; Heelis, R. A.; Reiff, P. H. 1988-01-01 Time-dependent aurora and magnetospheric convection parameterizations have been derived from solar wind and aurora particle data for November 21-22, 1981, and are used to drive the auroral and magnetospheric convection models that are embedded in the National Center for Atmospheric Research thermospheric general circulation model (TGCM). Neutral wind speeds and transition boundaries between the midlatitude solar-driven circulation and the high-latitude magnetospheric convection-driven circulation are examined on an orbit-by-orbit basis. The results show that TGCM-calculated winds and reversal boundary locations are in generally good agreement with Dynamics Explorer 2 measurements for the orbits studied. This suggests that, at least for this particular period of relatively moderate geomagnetic activity, the TGCM parameterizations on the eveningside of the auroral oval and polar cap are adequate. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JGRA..110.3204V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JGRA..110.3204V">Some characteristics of intense geomagnetic storms and their energy budget</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vichare, Geeta; Alex, S.; Lakhina, G. S. 2005-03-01 The present study analyses nine intense geomagnetic storms (∣Dst∣ > 175 nT) with the aid of ACE satellite measurements and ground magnetic field values at Alibag Magnetic Observatory. The study confirms the crucial role of southward IMF in triggering the storm main phase as well as controlling the magnitude of the storm. The main phase interval shows clear dependence on the duration of southward IMF. An attempt is made to identify the multipeak signature in the ring current energy injection rate during main phase of the storm. In order to quantify the energy budget of magnetic storms, the present paper computes the solar wind energies, magnetospheric coupling energies, auroral and Joule heating energies, and the ring current energies for each storm under examination. Computation of the solar wind- magnetosphere coupling function considers the variation of the size of the magnetosphere by using the measured solar wind ram pressure. During the main phase of the storm, the solar wind kinetic energy ranges from 9 × 1017 to 72 × 1017 J with an average of 30 × 1017 J; the total energy dissipated in the auroral ionosphere varies between 2 × 1015 and 9 × 1015 J, whereas ring current energies range from 8 × 1015 to 19 × 1015 J. For the total storm period, about 3.5% of total solar wind kinetic energy is available for the redistribution in the magnetosphere, and around 20% of this goes into the inner magnetosphere and in the auroral ionosphere of both the hemispheres. It is found that during main phase of the storm, almost 5% of the total solar wind kinetic energy is available for the redistribution in the magnetosphere, whereas during the recovery phase the percentage becomes 2.3%. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870013888','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870013888">Effect of double layers on magnetosphere-ionosphere coupling</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lysak, Robert L.; Hudson, Mary K. 1987-01-01 The Earth's auroral zone contains dynamic processes occurring on scales from the length of an auroral zone field line which characterizes Alfven wave propagation to the scale of microscopic processes which occur over a few Debye lengths. These processes interact in a time-dependent fashion since the current carried by the Alfven waves can excite microscopic turbulence which can in turn provide dissipation of the Alfven wave energy. This review will first describe the dynamic aspects of auroral current structures with emphasis on consequences for models of microscopic turbulence. A number of models of microscopic turbulence will be introduced into a large-scale model of Alfven wave propagation to determine the effect of various models on the overall structure of auroral currents. In particular, the effects of a double layer electric field which scales with the plasma temperature and Debye length is compared with the effect of anomalous resistivity due to electrostatic ion cyclotron turbulence in which the electric field scales with the magnetic field strength. It is found that the double layer model is less diffusive than in the resistive model leading to the possibility of narrow, intense current structures. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890020519','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890020519">The Soviet contributions towards MAP/WINE</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Rapoport, Z. TA.; Kazimirovsky, E. S. 1989-01-01 In the winter of 1983 to 1984, the research institutes of the Soviet Union took an active part in the accomplishment of the project Winter in Northern Europe (MAP/WINE) of the Middle Atmosphere Program. Different methods were used to measure temperature, direction and velocity of wind, turbulence, electron concentration in the lower ionosphere, and radio wave absorption. The study of the stratopheric warmings and the related changes in the mesosphere and lower ionosphere was considered of special importance. The analysis of the obtained data has shown, in particular, that during the stratospheric warmings the western wind in winter time becomes weaker and even reverses. At the same time period the electron concentration and the radio wave absorption in the lower ionosphere are often reduced. It is also observed that the high absorption zones move from west to east. These results confirm the concept about the role of the cyclonic circumpolar vortex in the transport of the auroral air to temperate latitudes and about the appearance of conditions for the winter anomalous radio wave absorption. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.2772W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.2772W">Solar Wind Properties During Juno's Approach to Jupiter: Data Analysis and Resulting Plasma Properties Utilizing a 1-D Forward Model</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wilson, R. J.; Bagenal, Fran; Valek, Philip W.; McComas, D. J.; Allegrini, Frederic; Ebert, Robert W.; Kim, Thomas K.; Kurth, W. S.; Szalay, Jamey R.; Thomsen, Michelle F. 2018-04-01 The Jovian Auroral Distributions Experiment ion sensor (JADE-I) on board the National Aeronautics and Space Administration's Juno mission measured solar wind ions for ≈40 days prior to the spacecraft's arrival at Jupiter, simultaneous with numerous telescope observations of the Jovian aurora. JADE-I is a thermal plasma time-of-flight instrument designed to measure Jovian auroral and magnetospheric ions. This study provides a solar wind parameter data set for the approach phase that may be used in coordinated studies with remote measurements of the Jovian aurora, to compare with models that propagate solar wind conditions from Earth and to apply to Jovian bow shock or magnetopause models. While multiple bow shock crossings were predicted during Juno's approach, there was only one observed suggesting a compressed magnetosphere that was shrinking as Juno approached. However, the calculated ram pressure at the bow shock was near the median value of those 40 days, rather than being in an upper percentile. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM53C2233F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM53C2233F">Generation of poleward moving auroral forms (PMAFs) during periods of dayside auroral oval expansions/contractions and periods when the dayside auroral oval is expanded and stable</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Fasel, G. J.; Flicker, J.; Sibeck, D. G.; Alyami, M.; Angelo, A.; Aylward, R. J.; Bender, S.; Christensen, M.; Kim, J.; Kristensen, H.; Orellana, Y.; Sahin, O.; Yoon, J.; Green, D.; Sigernes, F.; Lorentzen, D. A. 2013-12-01 The latitude of the equatorial edge of the dayside auroral oval has been shown to vary with the direction of the IMF Bz-component. The equatorward/poleward edge of the dayside auroral oval shifts equatorward/poleward when the IMF Bz-component is negative/positive [Burch, 1973; Akasofu, 1977; Horwitz and Akasofu, 1977; Sandholt et al., 1986, 1988]. Past studies have shown that poleward-moving auroral forms (PMAFs) are a common feature during equatorward expansions of the dayside auroral oval. Horwitz and Akasofu [1977] noted a one-to-one correspondence of luminous PMAFs associated with an equatorward expansion of the dayside auroral oval. During the southward turning of the IMF Bz-component the merging rate on the dayside increases [Newell and Meng, 1987] leading to the erosion of the dayside magnetopause. The field line merging process is thought to be most efficient when the interplanetary magnetic field (IMF) Bz-component turns southward. Both Vorobjev et al. [1975] and Horwitz and Akasofu [1977] attributed these PMAFs to magnetic flux being eroded away from the dayside magnetopause and transported antisunward. Dayside poleward-moving auroral forms are also observed during periods of an expanded and stable dayside auroral oval for both northern and southern hemisphere observations [Sandholt et al., 1986, 1989, 1990; Rairden and Mende, 1989; Mende et al., 1990]. Poleward-moving auroral forms have also been observed during some dayside oval contractions but have not been discussed much in the literature. This study examines the dayside auroral oval during periods of expansion, contraction, and during periods of an expanded and stable dayside auroral oval. This statistical study will provide the following results: number of poleward-moving auroral forms that are generated during dayside auroral oval expansions/contractions and during periods of a stable and expanded dayside auroral oval, the average initial and final elevation angle of the dayside auroral oval, time for dayside auroral oval to expand or contract, and the solar wind parameters (IMF Bx, By, Bz, speed, and pressure) associated with each interval (expansion, contraction, or stable and expanded). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Ap%26SS.361..295Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Ap%26SS.361..295Z">Geomagnetic and solar activity dependence of ionospheric upflowing O+: FAST observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zhao, K.; Jiang, Y.; Chen, K. W.; Huang, L. F. 2016-09-01 This paper investigates the dependence of the occurrence frequency of ionospheric upflowing oxygen (O+) ions on the sunspot cycle and geomagnetic activity. We examine the upflows response to the geomagnetic disturbances as well as the influence of the ion energy factor in controlling the magnitude of the occurrence frequency and the net energy flux. We discuss the spatial distribution of the upflow occurrence frequency and construct a regression model as a function of the magnetic latitude. The results show an overall enhancement of the upflow occurrence frequency during magnetically disturbed periods and indicate that the high-occurrence area spreads out from the source regions during magnetically quiet periods. The high-occurrence areas are located at 70° magnetic latitude (mLat) in the dayside auroral oval zone and between 76-80° mLat in the dayside polar cusp region. In the nightside auroral oval zone, these areas are near 60° mLat, penetrating further equatorward to 55° mLat during magnetically disturbed periods. High energy (≥1 keV) upflowing ions are common in the nightside auroral oval zone while low energy (<1 keV) upflowing ions are found escaping from the high latitude dayside cusp region. A Gaussian function is shown to be a good fit to the occurrence frequency over the magnetic latitude. For high energy upflowing O+ ions, the occurrence frequency exhibits a single peak located at about 60° mLat in the nightside auroral oval zone while for low energy upflowing O+ ions, it exhibits two peaks, one near 60° mLat in the auroral oval zone and the other near 78° mLat in the cusp region. We study the solar activity dependence by analyzing the relationship between the upflow occurrence frequency and the sunspot number (RZ). The statistical result shows that the frequency decreases with declining solar activity level, from ˜30 % at solar maximum to ˜5 % at solar minimum. In addition, the correlation coefficient between the occurrence frequency and RZ is 0.9. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870014816','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870014816">Auroral particles</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Evans, David S. 1987-01-01 The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/4793246-outer-radiation-belt-auroras','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4793246-outer-radiation-belt-auroras">OUTER RADIATION BELT AND AURORAS</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Gorchakov, E.V. 1961-01-01 Data obtained from Sputnik IH were used to determine the high-latitude boundary of the outer radiation belt and to interpret the nature of auroras. At the heights at which the auroras were observed, the outer boundary of the belt (69 deg north geomagnetic latitude) practically coincides with the auroral zone maximum (70 deg north geomagnetic latitude), while the maximum intensity of the outer belt near the earth lies at about 55 deg north geomagnetic latitude, i.e., at latitudes 15 deg below the auroral maximum. Consequently, auroras near the zone of maximum cannot be caused by the penetration into the atmospheremore » of electrons from the outer belt with energies on the order of 0.1 Mev (the mean energy of electrons in the outer belt). Other investigators have reported the detection of lowenergy streams at 55,000 to 75,000 km from the center of the earth in the equatorial plane. Moving toward the surface of the earth along the force lines of the magnetic field, electron streams of this type will reach the earth precisely in the region of the auroral zone maximum. It is considered possible that the electron streams are trapped at these distances from the earth and are at least partially responsible for auroras in the region of maximum. The existence of two maxima in the latitudinal distribution of auroral frequency, which attests to differert mechanisms of aurora formation, favors this hypothesis. In the region of the basic auroral maximum (70 deg north geomagnetic latitude) the auroras are the result of the invasion of belt particles, while in the region of the additional maximum (about 80 deg north geomagnetic latitude) they are caused by the direct penetration of corpuscular streams into the atmosphere. (OTS)« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740014875&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dnike','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740014875&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dnike">Resonances observed on mother-daughter rocket flights in the ionosphere. [signal frequency enhancement in auroral zones</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Folkestad, K.; Troeim, J. 1973-01-01 Resonance phenomena have been observed in swept frequency experiments carried out on two mother-daughter Nike-Tomahawk rocket flights at auroral latitudes. The experimental method is briefly described and characteristic samples of the results are presented. A possible interpretation of some main resonances is offered, involving cold plasma cone resonances. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/22654358-detectability-radio-auroral-emission-from-proxima','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654358-detectability-radio-auroral-emission-from-proxima">The Detectability of Radio Auroral Emission from Proxima b</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Burkhart, Blakesley; Loeb, Abraham Magnetically active stars possess stellar winds whose interactions with planetary magnetic fields produce radio auroral emission. We examine the detectability of radio auroral emission from Proxima b, the closest known exosolar planet orbiting our nearest neighboring star, Proxima Centauri. Using the radiometric Bode’s law, we estimate the radio flux produced by the interaction of Proxima Centauri’s stellar wind and Proxima b’s magnetosphere for different planetary magnetic field strengths. For plausible planetary masses, Proxima b could produce radio fluxes of 100 mJy or more in a frequency range of 0.02–3 MHz for planetary magnetic field strengths of 0.007–1 G. According tomore » recent MHD models that vary the orbital parameters of the system, this emission is expected to be highly variable. This variability is due to large fluctuations in the size of Proxima b’s magnetosphere as it crosses the equatorial streamer regions of dense stellar wind and high dynamic pressure. Using the MHD model of Garraffo et al. for the variation of the magnetosphere radius during the orbit, we estimate that the observed radio flux can vary nearly by an order of magnitude over the 11.2-day period of Proxima b. The detailed amplitude variation depends on the stellar wind, orbital, and planetary magnetic field parameters. We discuss observing strategies for proposed future space-based observatories to reach frequencies below the ionospheric cutoff (∼10 MHz), which would be required to detect the signal we investigate.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5017366-auroral-ray-imaging-from-high-low-earth-orbit','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5017366-auroral-ray-imaging-from-high-low-earth-orbit">Auroral x-ray imaging from high- and low-Earth orbit</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> McKenzie, D.L.; Gorney, D.J.; Imhof, W.L. Observations of bremsstrahlung x rays emitted by energetic electrons impacting the Earth's atmosphere can be used for remotely sensing the morphology, intensity, and energy spectra of electron precipitation from the magnetosphere. The utility of the technique is derived from the broad energy range of observable x rays (2 to > 100 KeV), the simple emission process, the large x-ray mean free path in the atmosphere, and negligible background. Two auroral x-ray imagers, developed for future spaceflights, are discussed. The Polar Ionospheric X-Ray Imaging Experiment is scheduled for launch on the NASA International Solar-Terrestrial Physics/Global Geospace Science program POLAR satellite inmore » 1994. The POLAR orbit, with an apogee and perigee of 9 and 1.8 R[sub e] (Earth radii), respectively, affords the opportunity to image the aurora from a high altitude above the north pole continuously for several hours. The Magnetospheric Atmospheric X-Ray Imaging Experiment (MAXIE) was launched aboard the NOAA-I satellite on August 8, 1993. The 800-km polar orbit passes over both the northern and southern auroral zones every 101 min. MAXIE will be capable of obtaining multiple images of the same auroral region during a single satellite orbit. The experimental approaches used to exploit these very different orbits for remote sensing of the Earth's auroral zones are emphasized.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA332515','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA332515">The WIND-HAARP Experiment: Initial Results of High Power Radiowave Interactions with Space Plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1997-11-10 Results from the first science experiment with the new HF Active Auroral Research Program ( HAARP ) facility in Alaska are reported. The initial...experiments involved transmission of high frequency waves from HAARP to the NASA/WIND satellite. The objective was to investigate the effects of space </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JGR...10428101L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JGR...10428101L">High-frequency and time resolution rocket observations of structured low- and medium-frequency whistler mode emissions in the auroral ionosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> LaBelle, J.; McAdams, K. L.; Trimpi, M. L. High bandwidth electric field waveform measurements on a recent auroral sounding rocket reveal structured whistler mode signals at 400-800 kHz. These are observed intermittently between 300 and 500 km with spectral densities 0-10 dB above the detection threshold of 1.5×10-11V2/m2Hz. The lack of correlation with local particle measurements suggests a remote source. The signals are composed of discrete structures, in one case having bandwidths of about 10 kHz and exhibiting rapid frequency variations of the order of 200 kHz per 100 ms. In one case, emissions near the harmonic of the whistler mode signals are detected simultaneously. Current theories of auroral zone whistler mode emissions have not been applied to explain quantitatively the fine structure of these signals, which resemble auroral kilometric radiation (AKR) rather than auroral hiss. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960001904','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960001904">Ultraviolet observations of the Saturnian north aurora and polar haze distribution with the HST-FOC</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gerard, J. C.; Dols, V.; Grodent, D.; Waite, J. H.; Gladstone, G. R.; Prange, R. 1995-01-01 Near simultaneous observations of the Saturnian H2 north ultraviolet aurora and the polar haze were made at 153 nm and 210 nm respectively with the Faint Object Camera on board the Hubble Space Telescope. The auroral observations cover a complete rotation of the planet and, when co-added, reveal the presence of an auroral emission near 80 deg N with a peak brightness of about 150 kR of total H2 emission. The maximum optical depth of the polar haze layer is found to be located approximately 5 deg equatorward of the auroral emission zone. The haze particles are presumably formed by hydrocarbon aerosols initiated by H2+ auroral production. In this case, the observed haze optical depth requires an efficiency of aerosol formation of about 6 percent, indicating that auroral production of hydrocarbon aerosols is a viable source of high-latitude haze. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840054162&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dconvection%2Bcurrents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840054162&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dconvection%2Bcurrents">A case-study of the evolution of polar-cap currents and auroral electrojets during polar geomagnetic disturbances with IMS magnetometer data</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Iijima, T.; Kim, J. S.; Sugiura, M. 1984-01-01 The development of the polar cap current and the relationship of that development to the evolution of auroral electrojets during individual polar geomagnetic disturbances is studied using 1 min average data from US-Canada IMS network stations and standard magnetograms from sites on the polar cap and in the auroral zone. It is found that even when the auroral electrojet activity is weak, polar cap currents producing fields of magnitude approximately 100-200 nT almost always exist. A normal convection current system exists quasi-persistently in the polar cap during extended quiet or weakly disturbed periods of auroral electrojet activity. After one such period, some drastic changes occur in the polar cap currents, which are followed by phases of growth, expansion, and recovery. Polar cap currents cannot all be completely ascribed to a single source mechanism. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM22A..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM22A..03H">Global MHD Modeling of Auroral Conjugacy for Different IMF Conditions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hesse, M.; Kuznetsova, M. M.; Liu, Y. H.; Birn, J.; Rastaetter, L. 2016-12-01 The question whether auroral features are conjugate or not, and the search for the underlying scientific causes is of high interest in magnetospheric and ionospheric physics. Consequently, this topic has attracted considerable attention in space-based observations of auroral features, and it has inspired a number of theoretical ideas and related modeling activities. Potential contributing factors to the presence or absence of auroral conjugacy include precipitation asymmetries in case of the diffuse aurora, inter-hemispherical conductivity differences, magnetospheric asymmetries brought about by, e.g., dipole tilt, corotation, or IMF By, and, finally, asymmetries in field-aligned current generation primarily in the nightside magnetosphere. In this presentation, we will analyze high-resolution, global MHD simulations of magnetospheric dynamics, with emphasis on auroral conjugacy. For the purpose of this study, we define controlled conditions by selecting solstice times with steady solar wind input, the latter of which includes an IMF rotation from purely southward to east-westward. Conductivity models will include both auroral precipaition proxies as well as the effects of the aysmmetric daylight. We will analyze these simulations with respect to conjugacies or the lack thereof, and study the role of the effects above in determing the former. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMSM51B2093G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMSM51B2093G">Mid-latitude SuperDARN Measurements of the Extended Local Time Structure and Dynamics of Sub-Auroral Plasma Streams</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Greenwald, R. A.; Ruohoniemi, J. M.; Shepherd, S. G.; Talaat, E. R.; Bristow, W. A.; Baker, J. B. 2011-12-01 Over the past several years, funding from the National Science Foundation Mid-Sized Infrastructure (MSI) Program has enabled the expansion of a mid-latitude network of SuperDARN HF radars. Currently the network spans the continental U.S.A and includes previously developed radars at Wallops Island and Blackstone, VA and four MSI-funded radars. Two of the MSI radars are located near Hays, Kansas and two are located near Christmas Valley, Oregon. With the current configuration of radars, it has been possible to detect sub-auroral plasma streams (SAPS), identified as latitudinally-narrow high-velocity flow regions equatorward of the main auroral electron precipitation zone, that extend over the breadth of the North American continent and the neighboring regions of the Atlantic and Pacific Oceans. SAPS have previously been reported using data from low-altitude polar-orbiting spacecraft, incoherent scatter radars, and the SuperDARN radars, but these are amongst the first observations of the SAPS velocity structure as it is observed over 6 or more hours of local time and for durations ranging up to 8 hours of real time. The SAPS flow channel is most clearly observed when there is good coupling between the solar wind and the Earth's magnetosphere (Southward IMF). As the IMF varies between southward and northward, the intensity of the flow is modulated, but the geomagnetic location of the SAPS channel does not change dramatically. To date, SAPS channels exhibiting the characteristics described above are most commonly observed under moderately disturbed conditions (Kp=3,4) and are commonly located near 60 degrees geomagnetic. The latitude of the SAPS feature decreases by several degrees between the dusk and midnight sectors. Overall, the SAPs feature appears to be an important localized flow enhancement that maps to a significant local time sector of the inner magnetosphere and it is surprisingly responsive to changes in solar-wind magnetosphere coupling. The extended ionospheric coverage provided by the SuperDARN network makes it an excellent tool to complement the data products of current and future multi-spacecraft missions. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active">5</li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active">6</li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930001976','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930001976">Modeling the Jovian aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Waite, J. Hunter, Jr. 1992-01-01 The Jovian aurora is the most powerful aurora in the solar system, over 100 times more powerful than the Earth's aurora. These magnificent visual displays can provide important information about the planetary magnetosphere which is responsible for the acceleration of energetic particles that produce aurora at any planet. Similarities and differences in planetary auroral emissions are thus a viable means of classifying and studying both comparative atmospheric and magnetospheric processes. For instance, at Earth the solar wind is the primary source of auroral power while at Jupiter it is conjectured that the rotation of the planet is the major source of magnetospheric and auroral power. The purpose of this IR project was to develop a model: (1) for use in interpreting the existing set of multispectral observations of Jupiter's aurora; and (2) to design new experiments based on the findings to improve understanding of the underlying auroral processes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A41I2398L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A41I2398L">Reconstructing Global-scale Ionospheric Outflow With a Satellite Constellation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Liemohn, M. W.; Welling, D. T.; Jahn, J. M.; Valek, P. W.; Elliott, H. A.; Ilie, R.; Khazanov, G. V.; Glocer, A.; Ganushkina, N. Y.; Zou, S. 2017-12-01 The question of how many satellites it would take to accurately map the spatial distribution of ionospheric outflow is addressed in this study. Given an outflow spatial map, this image is then reconstructed from a limited number virtual satellite pass extractions from the original values. An assessment is conducted of the goodness of fit as a function of number of satellites in the reconstruction, placement of the satellite trajectories relative to the polar cap and auroral oval, season and universal time (i.e., dipole tilt relative to the Sun), geomagnetic activity level, and interpolation technique. It is found that the accuracy of the reconstructions increases sharply from one to a few satellites, but then improves only marginally with additional spacecraft beyond 4. Increased dwell time of the satellite trajectories in the auroral zone improves the reconstruction, therefore a high-but-not-exactly-polar orbit is most effective for this task. Local time coverage is also an important factor, shifting the auroral zone to different locations relative to the virtual satellite orbit paths. The expansion and contraction of the polar cap and auroral zone with geomagnetic activity influences the coverage of the key outflow regions, with different optimal orbit configurations for each level of activity. Finally, it is found that reconstructing each magnetic latitude band individually produces a better fit to the original image than 2-D image reconstruction method (e.g., triangulation). A high-latitude, high-altitude constellation mission concept is presented that achieves acceptably accurate outflow reconstructions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990107392&hterms=conjunctions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dconjunctions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990107392&hterms=conjunctions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dconjunctions">Global Dynamics of Dayside Auroral Precipitation in Conjunction with Solar Wind Pressure Pulses</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Brittnacher, M.; Chua, D.; Fillingim, M.; Parks, G. K.; Spann, James F., Jr.; Germany, G. A.; Carlson, C. W.; Greenwald, R. A. 1999-01-01 Global observation of the dayside auroral region by the Ultraviolet Imager (UVI) during transient solar wind pressure pulse events on October 1, 1997 has revealed unusual features in the auroral precipitation. The auroral arc structure on the dayside, possibly connected with the LLBL, split into 2 arc structures; one moving poleward and fading over a 5 min period, and the other stationary or slightly shifted equatorward (by changes in the x component). The y component was large and positive, and the z component was small and negative. The splitting of the arc structure extended from 9 to 15 MLT and was concurrent with an enhancement of the convection in the cusp region identified by SuperDARN observations. The convection reversal on the morningside was adjacent to and poleward of the weak lower latitude band of precipitation. The sensitivity of the UVI instrument enabled observation of arc structures down to about 0.2 erg electron energy flux, as confirmed by comparison with particle measurements from the FAST satellite for other dayside events. Removal of the spacecraft wobble by PIXON image reconstruction restored the original resolution of the UVI of about 40 km from apogee. This event is being analyzed in connection with a larger study of global dynamics of dayside energy and momentum transfer related to changes in IMF conditions using UVI images in conjunction with observations from FAST and SuperDARN. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060032727&hterms=depletion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Ddepletion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060032727&hterms=depletion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Ddepletion">The Solar Wind Depletion (SWD) event of 26 April 1999: Triggering of an auroral pseudobreakup event</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Zhou, X.; Tsurutani, B.; Gonzalez, W. 2000-01-01 The interplanetary solar wind depletion (SWD) event of 26 April 1999 and its magnetospheric consequences are examined. The SWD event is characterized by a solar wind density decrease from [similar to] 3.0 to 0.7 cm(sup -3) leading to a solar wind ram pressure decrease from [similar to] 2.0 to 0.2 nPa. This SWD onset is followed by a dipolarization of nightside magnetospheric fields. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JASTP.146..129A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JASTP.146..129A">Auroral boundary movement rates during substorm onsets and their correspondence to solar wind and the AL index</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Andriyas, Tushar 2016-08-01 A statistical analysis of the equatorward and poleward auroral boundary movement during substorm onsets, the related solar wind activity, GOES 8 and 10 magnetic field, and the westward auroral electrojet (AL) index is undertaken, during the years 2000-2002. Auroral boundary data were obtained from the British Antarctic Survey (BAS). These boundaries were derived using auroral images from the IMAGE satellite. The timing of the onsets was derived from the Frey et al. (2004) database. Data were also classified based on the peak AL around the onset and the onset latitude, in order to analyze the differences, if any, in the rates of movement. It was found that the absolute ratio of the rate of movement of the mean poleward and equatorward boundaries was slower than the rate of mean movement around the midnight sector. The stronger the onset (in terms of the peak AL around the onset) was, the faster the rate of movement for both the boundaries. This implies that the stronger the AL signature around the onset, the weaker the magnetic field was prior to the onset and the faster it increased after the onset at GOES 8 and 10 locations. The stronger the AL signature, the thicker the latitudinal width of the aurora was, prior to the onset and higher was the increase in the width after the onset, due to large poleward and average equatorward expansion. Magnetotail field line stretching and relaxation rates as measured by GOES were also found to lie in the same order of magnitude. It is therefore concluded that the rates of latitudinal descent prior to a substorm onset and ascent after the onset, of the mean auroral boundaries, corresponds to the rate at which the tail field lines stretch and relax before and after the onset, respectively. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813943S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813943S">Investigating the auroral electrojets using Swarm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Smith, Ashley; Macmillan, Susan; Beggan, Ciaran; Whaler, Kathy 2016-04-01 The auroral electrojets are large horizontal currents that flow within the ionosphere in ovals around the polar regions. They are an important aspect of space weather and their position and intensity vary with solar wind conditions and geomagnetic activity. The electrojet positions are also governed by the Earth's main magnetic field. During more active periods, the auroral electrojets typically move equatorward and become more intense. This causes a range of effects on Earth and in space, including geomagnetically induced currents in power transmission networks, disturbance to radio communications and increased drag on satellites due to expansion of the atmosphere. They are also indicative of where the aurora are visible. Monitoring of the auroral electrojets in the pre-satellite era was limited to the network of ground-based magnetic observatories, from which the traditional AE activity indices are produced. These suffer in particular from the stations' poor distribution in position and so this motivates the use of satellite-based measurements. With polar low-Earth orbit satellites carrying magnetometers, all latitudes can be sampled with excellent resolution. This poster presents an investigation using Swarm's magnetometer data to detect the electrojets as the spacecraft move above them. We compare and contrast two approaches, one which uses vector data and the other which uses scalar data (Hamilton and Macmillan 2013, Vennerstrom and Moretto, 2013). Using ideas from both approaches we determine the oval positions and intensities from Swarm and earlier satellites. The variation in latitude and intensity with solar wind conditions, geomagnetic activity and secular variation of the main field is investigated. We aim to elucidate the relative importance of these factors. Hamilton, B. and Macmillan, S., 2013. Investigation of decadal scale changes in the auroral oval positions using Magsat and CHAMP data. Poster at IAGA 12th Scientific Assembly, 2013. http://nora.nerc.ac.uk/503037/ Vennerstrom, S. and Moretto, T., 2013. Monitoring auroral electrojets with satellite data. Space Weather, VOL. 11, 509-519, doi:10.1002/swe.20090 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.1273H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.1273H">O+ trough zones in the polar cap ionosphere-magnetosphere coupling region</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Horwitz, James; Zeng, Wen; Jaafari, Fajer Regions of low-density troughs in O+ have been observed at 1 RE altitude in the polar cap ionosphere-magnetosphere region by the Thermal Ion Dynamics Experiment(TIDE) on the POLAR spacecraft. In this presentation, the UT Arlington Dynamic Fluid-Kinetic (DyFK) code is employed to investigate the formation of such O+ density troughs. We utilize convection paths of flux tubes in the high-latitude region as prescribed by an empirical convection model with solar wind inputs to track the evolution of ionospheric plasma transport and in particular O+ densities along these tubes with time/space. The flux tubes are subjected to auroral processes of precipitation and wave-driven ion heating when they pass through the auroral oval, which tends to elevate the plasma densities in these tubes. When the F-regions of such tubes traverse locations where the F-region is in darkness, recombination there causes the higher-altitude regions to drain and the densities to decline throughout. Owing to the varying effects of these processes, significant and low trough-like densities at higher altitudes developed along these flux tubes. The modeled densities near 6000 km altitudes will be compared with multiple POLAR passes featuring POLAR/TIDE-measured O+ densities for inside and outside of such trough regions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5378029-long-term-variation-radar-auroral-backscatter-interplanetary-sector-structure','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5378029-long-term-variation-radar-auroral-backscatter-interplanetary-sector-structure">Long-term variation of radar-auroral backscatter and the interplanetary sector structure</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Yeoman, T.K.; Burrage, M.D.; Lester, M. Recurrent variation of geomagnetic activity at the {approximately}27-day solar rotation period and higher harmonics is a well-documented phenomenon. Auroral radar backscatter data from the Sweden and Britain Radar-Auroral Experiment (SABRE) radar provide a continuous time series from 1981 to the present which is a highly sensitive monitor of geomagnetic activity. In this study, Maximum Entropy Method (MEM) dynamic power spectra of SABRE backscatter data from 1981 to 1989, concurrent interplanetary magnetic field (IMF) and solar wind parameters from 1981 to 1987, and the Kp index since 1932 are examined. Data since 1977 are compared with previously published heliospheric current sheetmore » measurements mapped out from the solar photosphere. Stong periodic behavior is observed in the radar backscatter during the declining phase of solar cycle 21, but this periodicity disappears at the start of solar cycle 22. Similar behavior is observed in earlier solar cycles in the Kp spectra. Details of the radar backscatter, IMF, and solar wind spectra indicate that the solar wind momentum density is the dominant parameter in determining the backscatter periodicity. The temporal evolution of two- and four-sector structures, as predicted by SABRE backscatter spectra, throughout solar cycle 21 generally still agree well with heliospheric current sheet measurements. For one interval, however, there is evidence that evolution of the current sheet has occurred between the photospheric source surface and the Earth.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DPS....4911523T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DPS....4911523T">Multiple Excitation Regimes in Jupiter’s Polar Aurorae</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Trafton, Laurence M. 2017-10-01 Since the Voyager epoch, it has been known that the thermospheres of all the outer planets are heated to a temperature over 3 times higher than can be explained by solar EUV (Yelle & Miller 2000). The dominant heat source is still an open question. Without this knowledge, one cannot understand the structure, energy balance, and seasonal evolution of outer planet upper atmospheres. Majeed et al. (2009) suggest that the main ionospheric heat source driving the thermospheric flow at high Jovian latitudes is Joule currents resulting from the frictional motion of the ions relative to the neutrals, while particle precipitation dominates the heating of the auroral ovals at exospheric altitudes. However, since the diffuse emission interior to the oval is not directly connected to a source in the magnetosphere, and vice versa, separate processes may drive the heating in the auroral oval and the zone within. Because the latter’s open field lines expose it to “space weather”, it is subject to thermospheric heating by the solar wind, coronal mass ejections, and reconnection in the Jovian magnetotail.H3+ plays an important role in the cooling and stabilizing of hydrogenic planetary thermospheres (Miller et al. 2000). For Jupiter's hot upper atmosphere, above the homopause at ~1 µbar, H3+ appears to be the dominant coolant, so that the local heating rate may be estimated by measuring the H3+ emission flux. Consequently, the morphology and spectrum of the H3+ emission flux should be heavily influenced by, and so provide the clearest signature of, the unknown heating process. A study of Jupiter’s H3+ emission may therefore help to isolate and constrain that dominant process. Towards that end, we surveyed Jupiter's northern and southern auroral zones near pre-opposition quadrature on May 11 and 12, 2009, by obtaining emission line spectra between 3-4 microns at Keck II with NIRSPEC. The southern spectra resolve at least three contrarily excited H3+ emission spectra simultaneously, suggesting at least three distinct excitation processes operating within Jupiter's polar aurorae. The emission morphology cannot be explained by the observing geometry nor viewing aspect. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4840202G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4840202G">Juno Ultraviolet Spectrograph (Juno-UVS) Observations of Jupiter during Approach</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gladstone, Randy; Versteeg, Maarten; Greathouse, Thomas K.; Hue, Vincent; Davis, Michael; Gerard, Jean-Claude; Grodent, Denis; Bonfond, Bertrand 2016-10-01 We present the initial results from Juno Ultraviolet Spectrograph (Juno-UVS) observations of Jupiter obtained during approach in June 2016. Juno-UVS is an imaging spectrograph with a bandpass of 70<λ<205 nm. This wavelength range includes all important ultraviolet (UV) emissions from the H2 bands and the H Lyman series which are produced in Jupiter's auroras, and also the absorption signatures of aurorally-produced hydrocarbons. The Juno-UVS instrument telescope has a 4 x 4 cm2 input aperture and uses an off-axis parabolic primary mirror. A flat scan mirror situated near the entrance of the telescope is used to observe at up to ±30° perpendicular to the Juno spin plane. The light is focused onto the spectrograph entrance slit, which has a "dog-bone" shape 7.2° long, in three sections of 0.2°, 0.025°, and 0.2° width (as projected onto the sky). Light entering the slit is dispersed by a toroidal grating which focuses UV light onto a curved microchannel plate (MCP) cross delay line (XDL) detector with a solar blind UV-sensitive CsI photocathode. Tantalum surrounds the spectrograph assembly to shield the detector and its electronics from high-energy electrons. All other electronics are located in Juno's spacecraft vault, including redundant low-voltage and high-voltage power supplies, command and data handling electronics, heater/actuator electronics, scan mirror electronics, and event processing electronics. The purpose of Juno-UVS is to remotely sense Jupiter's auroral morphology and brightness to provide context for in situ measurements by Juno's particle instruments. Prior to Jupiter Orbit Insertion (JOI) on July 5, Juno approach observations provide a rare opportunity to correlate local solar wind conditions with Jovian auroral emissions. Some of Jupiter's auroral emissions (e.g., polar emissions) may be controlled or at least affected by the solar wind. Here we compare synoptic Juno-UVS observations of Jupiter's auroral emissions (~40 minutes per hour, acquired during 2016 June 3-30) with in situ solar wind observations, as well as related Jupiter observations obtained from Earth. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA44A..06K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA44A..06K">Climatology of Neutral vertical winds in the midlatitude thermosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kerr, R.; Kapali, S.; Riccobono, J.; Migliozzi, M. A.; Noto, J.; Brum, C. G. M.; Garcia, R. 2017-12-01 More than one thousand measurements of neutral vertical winds, relative to an assumed average of 0 m/s during a nighttime period, have been made at Arecibo Observatory and the Millstone Hill Optical Facility since 2012, using imaging Fabry-Perot interferometers. These instruments, tuned to the 630 nm OI emission, are carefully calibrated for instrumental frequency drift using frequency stabilized lasers, allowing isolation of Doppler motion in the zenith with 1-2 m/s accuracy. As one example of the results, relative vertical winds at Arecibo during quiet geomagnetic conditions near winter solstice 2016, range ±70 m/s and have a one standard deviation statistical variability of ±34 m/s. This compares with a ±53 m/s deviation from the average meridional wind, and a ±56 m/s deviation from the average zonal wind measured during the same period. Vertical neutral wind velocities for all periods range from roughly 30% - 60% of the horizontal velocity domain at Arecibo. At Millstone Hill, the vertical velocities relative to horizontal velocities are similar, but slightly smaller. The midnight temperature maximum at Arecibo is usually correlated with a surge in the upward wind, and vertical wind excursions of more than 80 m/s are common during magnetic storms at both sites. Until this compilation of vertical wind climatology, vertical motions of the neutral atmosphere outside of the auroral zone have generally been assumed to be very small compared to horizontal transport. In fact, excursions from small vertical velocities in the mid-latitude thermosphere near the F2 ionospheric peak are common, and are not isolated events associated with unsettled geomagnetic conditions or other special dynamic conditions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMED11A0841N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMED11A0841N">An Undergraduate Student Instrumentation Project (USIP) to Develop New Instrument Technology to Study the Auroral Ionosphere and Stratospheric Ozone Layer Using Ultralight Balloon Payloads</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nowling, M.; Ahmad, H.; Gamblin, R.; Guala, D.; Hermosillo, D.; Pina, M.; Marrero, E.; Canales, D. R. J.; Cao, J.; Ehteshami, A.; Bering, E. A., III; Lefer, B. L.; Dunbar, B.; Bias, C.; Shahid, S. 2015-12-01 This project is currently engaging twelve undergraduate students in the process of developing new technology and instrumentation for use in balloon borne geospace investigations in the auroral zone. Motivation stems from advances in microelectronics and consumer electronic technology. Given the technological innovations over the past 20 years it now possible to develop new instrumentation to study the auroral ionosphere and stratospheric ozone layer using ultralight balloon payloads for less than 6lbs and $3K per payload. The University of Houston Undergraduate Student Instrumentation Project (USIP) team has built ten such payloads for launch using 1500 gm latex weather balloons deployed in Houston, TX, Fairbanks, AK, and as well as zero pressure balloons launched from northern Sweden. The latex balloon project will collect vertical profiles of wind velocity, temperature, electrical conductivity, ozone, and odd nitrogen. This instrument payload will also produce profiles of pressure, electric field, and air-earth electric current. The zero pressure balloons will obtain a suite of geophysical measurements including: DC electric field, electric field and magnetic flux, optical imaging, total electron content of ionosphere via dual-channel GPS, X-ray detection, and infrared/UV spectroscopy. Students flew payloads with different combinations of these instruments to determine which packages are successful. Data collected by these instruments will be useful in understanding the nature of electrodynamic coupling in the upper atmosphere and how the global earth system is changing. Twelve out of the launched fifteen payloads were successfully launched and recovered. Results and best practices learned from lab tests and initial Houston test flights will be discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800021439','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800021439">The relationships between high latitude convection reversals and the energetic particle morphology observed by the Atmosphere Explorer</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Heelis, R. A.; Winningham, J. D.; Hanson, W. B.; Burch, J. L. 1980-01-01 Simultaneous measurements of the auroral zone particle precipitation and the ion convection velocity by Atmosphere Explorer show a consistent difference between the location of the poleward boundary of the auroral particle precipitation and the ion convection reversal. The difference of about 1.5 degrees of invariant latitude is such that some part of the antisunward convection lies wholly within the auroral particle precipitation region. The nature of the convection reversals within the precipitation region suggests that in this region the convection electric field is generated on closed field lines that connect in the magnetosphere to the low latitude boundary layer. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840065484&hterms=balance+general&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dbalance%2Bgeneral','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840065484&hterms=balance+general&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dbalance%2Bgeneral">An analysis of the high-latitude thermospheric wind pattern calculated by a thermospheric general circulation model. I - Momentum forcing</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Killeen, T. L.; Roble, R. G. 1984-01-01 A diagnostic processor (DP) was developed for analysis of hydrodynamic and thermodynamic processes predicted by the NCAR thermospheric general circulation model (TGCM). The TGCM contains a history file on the projected wind, temperature and composition fields at each grid point for each hour of universal time. The DP assimilates the history file plus ion drag tensors and drift velocities, specific heats, coefficients of viscosity, and thermal conductivity and calculates the individual forcing terms for the momentum and energy equations for a given altitude. Sample momentum forcings were calculated for high latitudes in the presence of forcing by solar radiation and magnetospheric convection with a 60 kV cross-tail potential, i.e., conditions on Oct. 21, 1981. It was found that ion drag and pressure forces balance out at F region heights where ion drift velocities are small. The magnetic polar cap/auroral zone boundary featured the largest residual force or net acceleration. Diurnal oscillations were detected in the thermospheric convection, and geostrophic balance was dominant in the E layer. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950048909&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dlazarus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950048909&hterms=lazarus&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D40%26Ntt%3Dlazarus">Solar wind oscillations with a 1.3 year period</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Richardson, John D.; Paularena, Karolen I.; Belcher, John W.; Lazarus, Alan J. 1994-01-01 The Interplanetary Monitoring Platform 8 (IMP-8) and Voyager 2 spacecraft have recently detected a very strong modulation in the solar wind speed with an approximately 1.3 year period. Combined with evidence from long-term auroral and magnetometer studies, this suggests that fundamental changes in the Sun occur on a roughly 1.3 year time scale. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA127042','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA127042">Auroral-Region Dynamics Determined with the Chatanika Radar.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1982-11-01 report) 17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, If different from report) 18 . SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on...for 1 April 1973 .......... ... 41 18 Vertical Neutral Wind Measured with the Fabry-Perot Interferometer ......... ........................ ... 44 vii...Waves Determined from Radar Observations on 18 January 1976 ..... ............... ... 50 23 Meridional Wind and Gravity Waves Determined from Radar </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998sct..conf...55A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998sct..conf...55A">Surface Charging in the Auroral Zone on the DMSP Spacecraft in LEO</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Anderson, Phillip C. 1998-11-01 A recent anomaly on the DMSP F13 spacecraft was attributed to an electrical malfunction caused by an electrostatic discharge on the vehicle associated with surface charging. It occurred during an intense energetic electron precipitation event (an auroral arc) within a region of very low plasma density in the auroral zone. A study of 1.5 year's worth of DMSP data from three satellites acquired during the recent minimum in the solar cycle has shown that such charging was a common occurrence with 704 charging events found. This is the result of significantly reduced background plasma densities associated with the solar minimum; smaller than ever previously experienced by the DMSP spacecraft. At times, the spacecraft charged for periods of 10s of seconds as they skimmed along an auroral arc instead of cutting across it. We show examples of the observed plasma density and the precipitating electron and ion spectra associated with the charging, and the MLT distribution and the seasonal distribution of the events. The preponderance of events occurred in the premidnight and morning sectors with two types of electron spectra being observed: a sharply peaked distribution indicative of field-aligned acceleration in the premidnight sector and a very hard distribution in the morning sector. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSH11C2268J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSH11C2268J">Spatial correlation of auroral zone geomagnetic variations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jackel, B. J.; Davalos, A. 2016-12-01 Magnetic field perturbations in the auroral zone are produced by a combination of distant ionospheric and local ground induced currents. Spatial and temporal structure of these currents is scientifically interesting and can also have a significant influence on critical infrastructure.Ground-based magnetometer networks are an essential tool for studying these phenomena, with the existing complement of instruments in Canada providing extended local time coverage. In this study we examine the spatial correlation between magnetic field observations over a range of scale lengths. Principal component and canonical correlation analysis are used to quantify relationships between multiple sites. Results could be used to optimize network configurations, validate computational models, and improve methods for empirical interpolation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900054856&hterms=dark+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddark%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900054856&hterms=dark+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddark%2Benergy">Energy coupling in the magnetospheres of earth and Mercury</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Baker, D. N. 1990-01-01 The mechanisms involved in the dissipation of solar-wind energy during magnetospheric substorms are considered theoretically, comparing models for earth and Mercury. In the model for terrestrial substorms, IMF lines interconnect with terrestrial field lines near the front of the magnetosphere and are dragged back, carrying plasma and energy, to form tail lobes; a magnetic neutral region is then formed by reconnection of the open lines as the plasma sheet thins, and reconnective heating and acceleration of tail plasma lead to plasma inflow at the poles and formation of a plasmoid flowing down the tail at high velocity. Analogous phenomena on Mercury could produce precipitation of particles carrying 10-1000 GW of power into 'auroral zones' on the dark side of the planet. The feasibility of remote or in situ observations to detect such processes is discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26709318','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26709318">First light from a kilometer-baseline Scintillation Auroral GPS Array.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Datta-Barua, S; Su, Y; Deshpande, K; Miladinovich, D; Bust, G S; Hampton, D; Crowley, G 2015-05-28 We introduce and analyze the first data from an array of closely spaced Global Positioning System (GPS) scintillation receivers established in the auroral zone in late 2013 to measure spatial and temporal variations in L band signals at 100-1000 m and subsecond scales. The seven receivers of the Scintillation Auroral GPS Array (SAGA) are sited at Poker Flat Research Range, Alaska. The receivers produce 100 s scintillation indices and 100 Hz carrier phase and raw in-phase and quadrature-phase samples. SAGA is the largest existing array with baseline lengths of the ionospheric diffractive Fresnel scale at L band. With an initial array of five receivers, we identify a period of simultaneous amplitude and phase scintillation. We compare SAGA power and phase data with collocated 630.0 nm all-sky images of an auroral arc and incoherent scatter radar electron precipitation measurements, to illustrate how SAGA can be used in multi-instrument observations for subkilometer-scale studies. A seven-receiver Scintillation Auroral GPS Array (SAGA) is now at Poker Flat, Alaska SAGA is the largest subkilometer array to enable phase/irregularities studies Simultaneous scintillation, auroral arc, and electron precipitation are observed. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active">6</li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active">7</li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4681424','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4681424">First light from a kilometer-baseline Scintillation Auroral GPS Array</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Datta-Barua, S; Su, Y; Deshpande, K; Miladinovich, D; Bust, G S; Hampton, D; Crowley, G 2015-01-01 We introduce and analyze the first data from an array of closely spaced Global Positioning System (GPS) scintillation receivers established in the auroral zone in late 2013 to measure spatial and temporal variations in L band signals at 100–1000 m and subsecond scales. The seven receivers of the Scintillation Auroral GPS Array (SAGA) are sited at Poker Flat Research Range, Alaska. The receivers produce 100 s scintillation indices and 100 Hz carrier phase and raw in-phase and quadrature-phase samples. SAGA is the largest existing array with baseline lengths of the ionospheric diffractive Fresnel scale at L band. With an initial array of five receivers, we identify a period of simultaneous amplitude and phase scintillation. We compare SAGA power and phase data with collocated 630.0 nm all-sky images of an auroral arc and incoherent scatter radar electron precipitation measurements, to illustrate how SAGA can be used in multi-instrument observations for subkilometer-scale studies. Key Points A seven-receiver Scintillation Auroral GPS Array (SAGA) is now at Poker Flat, Alaska SAGA is the largest subkilometer array to enable phase/irregularities studies Simultaneous scintillation, auroral arc, and electron precipitation are observed PMID:26709318 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110023538&hterms=kellogg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dkellogg','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110023538&hterms=kellogg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dkellogg">Large Amplitude Whistlers in the Magnetosphere Observed with Wind-Waves</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kellogg, P. J.; Cattell, C. A.; Goetz, K.; Monson, S. J.; Wilson, L. B., III 2011-01-01 We describe the results of a statistical survey of Wind-Waves data motivated by the recent STEREO/Waves discovery of large-amplitude whistlers in the inner magnetosphere. Although Wind was primarily intended to monitor the solar wind, the spacecraft spent 47 h inside 5 R(sub E) and 431 h inside 10 R(sub E) during the 8 years (1994-2002) that it orbited the Earth. Five episodes were found when whistlers had amplitudes comparable to those of Cattell et al. (2008), i.e., electric fields of 100 m V/m or greater. The whistlers usually occurred near the plasmapause. The observations are generally consistent with the whistlers observed by STEREO. In contrast with STEREO, Wind-Waves had a search coil, so magnetic measurements are available, enabling determination of the wave vector without a model. Eleven whistler events with useable magnetic measurements were found. The wave vectors of these are distributed around the magnetic field direction with angles from 4 to 48deg. Approximations to observed electron distribution functions show a Kennel-Petschek instability which, however, does not seem to produce the observed whistlers. One Wind episode was sampled at 120,000 samples/s, and these events showed a signature that is interpreted as trapping of electrons in the electrostatic potential of an oblique whistler. Similar waveforms are found in the STEREO data. In addition to the whistler waves, large amplitude, short duration solitary waves (up to 100 mV/m), presumed to be electron holes, occur in these passes, primarily on plasma sheet field lines mapping to the auroral zone. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740055246&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231041','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740055246&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3D%2526%25231041">An analysis of the upper atmospheric wind observed by LOGACS. [satellite Low-G Accelerometer Calibration System</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Wu, S. T.; Matsushita, S.; Devries, L. L. 1974-01-01 Wind velocities at 140 to 200 km altitude were observed by a low-g accelerometer calibration system (LOGACS) flown on an Agena satellite during a geomagnetic storm. An interesting wind reversal observed by the satellite at auroral latitudes is satisfactorily explained by the neutral air motion caused by the E x B drift deduced from the ground-based geomagnetic data recorded at stations near the meridian of the satellite orbit. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA564003','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA564003">Contamination and Micropropulsion Technology</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2012-07-01 23, 027101 (2011) Evaluation of active flow control applied to wind turbine blade section J. Renewable Sustainable Energy 2, 063101 (2010) Effect...field lines at high latitudes where solar wind electrons can readily access the upper atmosphere. The electron energy distribution in the auroral... slip behavior of n-hexadecane in large amplitude oscillatory shear flow via nonequilibrium molecular dynamic simulation J. Chem. Phys. 136, 104904 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998GeoRL..25.2033E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998GeoRL..25.2033E">The auroral current circuit and field-aligned currents observed by FAST</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Elphic, R. C.; Bonnell, J. W.; Strangeway, R. J.; Kepko, L.; Ergun, R. E.; McFadden, J. P.; Carlson, C. W.; Peria, W.; Cattell, C. A.; Klumpar, D.; Shelley, E.; Peterson, W.; Moebius, E.; Kistler, L.; Pfaff, R. FAST observes signatures of small-scale downward-going current at the edges of the inverted-V regions where the primary (auroral) electrons are found. In the winter pre-midnight auroral zone these downward currents are carried by upward flowing low- and medium-energy (up to several keV) electron beams. FAST instrumentation shows agreement between the current densities inferred from both the electron distributions and gradients in the magnetic field. FAST data taken near apogee (˜4000-km altitude) commonly show downward current magnetic field deflections consistent with the observed upward flux of ˜109 electrons cm-2 s-1, or current densities of several µA m-2. The electron, field-aligned current and electric field signatures indicate the downward currents may be associated with “black aurora” and auroral ionospheric cavities. The field-aligned voltage-current relationship in the downward current region is nonlinear. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900054436&hterms=MOOS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMOOS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900054436&hterms=MOOS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMOOS">Long-term study of longitudinal dependence in primary particle precipitation in the north Jovian aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Livengood, T. A.; Strobel, D. F.; Moos, H. W. 1990-01-01 The wavelength-dependent absorption apparent in IUE spectra of the north Jovian aurora is analyzed to determine the column density of hydrocarbons above the altitude of the FUV auroral emission. Both the magnetotail and torus auroral zone models are considered in estimating zenith angles, with very similar results obtained for both models. It is found that the hydrocarbon column density above the FUV emission displays a consistent dependence on magnetic longitude, with the peak density occurring approximately coincident with the peak in the observed auroral intensity. Two distinct scenarios for the longitude dependence of the column density are discussed. In one, the Jovian upper atmosphere is longitudinally homogeneous, and the variation in optical depth is due to a variation in penetration, and thus energy, of the primary particles. In the other, the energy of the primaries is longitudinally homogeneous, and it is aeronomic properties which change, probably due to auroral heating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730013584','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730013584">Spectrophotometry of planetary atmosphere from the X-15 rocket airplane</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Murcray, W. B. 1973-01-01 Nike-Apache and Nike-Tomahawk rocket flights using spectrophotometric techniques to investigate auroral activity are reported. The specific objectives were to obtain data relative to typical auroral situations, including quiet pre-breakup auroras, westward traveling surges, breakup auroras, and post-breakup auroras. It was found that excited atoms move considerable distances between excitation and emission owing to the high velocity wind conditions prevailing above 200 km. Based on the results of these observations, recommendations are made for future studies of ionized atmospheric activity at higher altitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM31C2515G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM31C2515G">Considerations of solar wind dynamics in mapping of Jupiter's auroral features to magnetospheric sources</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gyalay, S.; Vogt, M.; Withers, P. 2015-12-01 Previous studies have mapped locations from the magnetic equator to the ionosphere in order to understand how auroral features relate to magnetospheric sources. Vogt et al. (2011) in particular mapped equatorial regions to the ionosphere by using a method of flux equivalence—requiring that the magnetic flux in a specified region at the equator is equal to the magnetic flux in the region to which it maps in the ionosphere. This is preferred to methods relying on tracing field lines from global Jovian magnetic field models, which are inaccurate beyond 30 Jupiter radii from the planet. That previous study produced a two-dimensional model—accounting for changes with radial distance and local time—of the normal component of the magnetic field in the equatorial region. However, this two-dimensional fit—which aggregated all equatorial data from Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Ulysses, and Galileo—did not account for temporal variability resulting from changing solar wind conditions. Building off of that project, this study aims to map the Jovian aurora to the magnetosphere for two separate cases: with a nominal magnetosphere, and with a magnetosphere compressed by high solar wind dynamic pressure. Using the Michigan Solar Wind Model (mSWiM) to predict the solar wind conditions upstream of Jupiter, intervals of high solar wind dynamic pressure were separated from intervals of low solar wind dynamic pressure—thus creating two datasets of magnetometer measurements to be used for two separate 2D fits, and two separate mappings. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Natur.554..337K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Natur.554..337K">Pulsating aurora from electron scattering by chorus waves</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kasahara, S.; Miyoshi, Y.; Yokota, S.; Mitani, T.; Kasahara, Y.; Matsuda, S.; Kumamoto, A.; Matsuoka, A.; Kazama, Y.; Frey, H. U.; Angelopoulos, V.; Kurita, S.; Keika, K.; Seki, K.; Shinohara, I. 2018-02-01 Auroral substorms, dynamic phenomena that occur in the upper atmosphere at night, are caused by global reconfiguration of the magnetosphere, which releases stored solar wind energy. These storms are characterized by auroral brightening from dusk to midnight, followed by violent motions of distinct auroral arcs that suddenly break up, and the subsequent emergence of diffuse, pulsating auroral patches at dawn. Pulsating aurorae, which are quasiperiodic, blinking patches of light tens to hundreds of kilometres across, appear at altitudes of about 100 kilometres in the high-latitude regions of both hemispheres, and multiple patches often cover the entire sky. This auroral pulsation, with periods of several to tens of seconds, is generated by the intermittent precipitation of energetic electrons (several to tens of kiloelectronvolts) arriving from the magnetosphere and colliding with the atoms and molecules of the upper atmosphere. A possible cause of this precipitation is the interaction between magnetospheric electrons and electromagnetic waves called whistler-mode chorus waves. However, no direct observational evidence of this interaction has been obtained so far. Here we report that energetic electrons are scattered by chorus waves, resulting in their precipitation. Our observations were made in March 2017 with a magnetospheric spacecraft equipped with a high-angular-resolution electron sensor and electromagnetic field instruments. The measured quasiperiodic precipitating electron flux was sufficiently intense to generate a pulsating aurora, which was indeed simultaneously observed by a ground auroral imager. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910001421','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910001421">A mathematical model of the structure and evolution of small scale discrete auroral arcs</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Seyler, C. E. 1990-01-01 A three dimensional fluid model which includes the dispersive effect of electron inertia is used to study the nonlinear macroscopic plasma dynamics of small scale discrete auroral arcs within the auroral acceleration zone and ionosphere. The motion of the Alfven wave source relative to the magnetospheric and ionospheric plasma forms an oblique Alfven wave which is reflected from the topside ionosphere by the negative density gradient. The superposition of the incident and reflected wave can be described by a steady state analytical solution of the model equations with the appropriate boundary conditions. This two dimensional discrete auroral arc equilibrium provides a simple explanation of auroral acceleration associated with the parallel electric field. Three dimensional fully nonlinear numerical simulations indicate that the equilibrium arc configuration evolves three dimensionally through collisionless tearing and reconnection of the current layer. The interaction of the perturbed flow and the transverse magnetic field produces complex transverse structure that may be the origin of the folds and curls observed to be associated with small scale discrete arcs. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860019850','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860019850">Zonal wind observations during a geomagnetic storm</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Miller, N. J.; Spencer, N. W. 1986-01-01 In situ measurements taken by the Wind and Temperature Spectrometer (WATS) onboard the Dynamics Explorer 2 spacecraft during a geomagnetic storm display zonal wind velocities that are reduced in the corotational direction as the storm intensifies. The data were taken within the altitudes 275 to 475 km in the dusk local time sector equatorward of the auroral region. Characteristic variations in the value of the Dst index of horizontal geomagnetic field strength are used to monitor the storm evolution. The detected global rise in atmospheric gas temperature indicates the development of thermospheric heating. Concurrent with that heating, reductions in corotational wind velocities were measured equatorward of the auroral region. Just after the sudden commencement, while thermospheric heating is intense in both hemispheres, eastward wind velocities in the northern hemisphere show reductions ranging from 500 m/s over high latitudes to 30 m/s over the geomagnetic equator. After 10 hours storm time, while northern thermospheric heating is diminishing, wind velocity reductions, distinct from those initially observed, begin to develop over southern latitudes. In the latter case, velocity reductions range from 300 m/s over the highest southern latitudes to 150 m/s over the geomagnetic equator and extend into the Northern Hemisphere. The observations highlight the interhemispheric asymmetry in the development of storm effects detected as enhanced gas temperatures and reduced eastward wind velocities. Zonal wind reductions over high latitudes can be attributed to the storm induced equatorward spread of westward polar cap plasma convection and the resulting plasma-neutral collisions. However, those collisions are less significant over low latitudes; so zonal wind reductions over low latitudes must be attributed to an equatorward extension of a thermospheric circulation pattern disrupted by high latitude collisions between neutrals transported via eastward winds and ions convecting westward. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820015133','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820015133">The application of soft X-ray imaging techniques to auroral research</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 1981-01-01 The feasibility of building and operating a grazing incidence X-ray telescope for auroral zone studies from the Polar Plasma Laboratory (PPL) is discussed. A detailed structural analysis of the preferred design, an array of seven nested Wolter mirrors, is presented. An engineering evaluation of the requirements for the instrumental configuration, power, weight and telemetry is included. The problems of radiation hardening and thermal control are discussed. The resulting strawman instrument is presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/4432418-observations-narrow-microburst-trains-geomagnetic-storm-august','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4432418-observations-narrow-microburst-trains-geomagnetic-storm-august">Observations of narrow microburst trains in the geomagnetic storm of August 4-6, 1972</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Brown, R.R. 1973-04-01 In the intense geomagnetic disturbances of early August 1972, auroral zone microburst trains were observed at balloon altitude and found to be significantly narrower in burst width and spacing than microbursts found previously at the same site. These observations suggest that the spacing of microburst peaks, as well as their width, is related to variations in the power spectrum of a magnetospheric acceleration process rather than the bounce motions of electrons in the geomagnetic field or the modulation of electron precipitation by drift waves in magnetospheric plasma. In the geomagnetic activity that followed the solar flares in early August 1972,more » intense fluxes of auroral x rays were encountered during balloon flights launched from College, Alaska. Although much of the time variations of the x-ray fluxes observed during these flights represented known features of electron precipitation at auroral latitudes, one new and distinct feature was evident. In particular, it was found that the widths and spacings of auroral zone microbursts (Anderson and Milton, 1964) on this occasion were significantly smaller than those observed previously on many balloon flights from the same site. Thus, instead of microburst trains with widths at half-intensity points of ~0.2 sec and spacings of ~0.6 sec, the majority of the microbursts encountered on two flights from College had widths of ~0.1 sec and spacings of ~0.4 sec. (auth)« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.6635D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.6635D">Trajectories of thermospheric air parcels flowing over Alaska, reconstructed from ground-based wind measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dhadly, Manbharat; Conde, Mark 2017-06-01 It is widely presumed that the convective stability and enormous kinematic viscosity of Earth's upper thermosphere hinders development of both horizontal and vertical wind shears and other gradients. Any strong local structure (over scale sizes of several hundreds of kilometers) that might somehow form would be expected to dissipate rapidly. Air flow in such an atmosphere should be relatively simple, and transport effects only slowly disperse and mix air masses. However, our observations show that wind fields in Earth's thermosphere have much more local-scale structure than usually predicated by current modeling techniques, at least at auroral latitudes; they complicate air parcel trajectories enormously, relative to typical expectations. For tracing air parcels, we used wind measurements of an all-sky Scanning Doppler Fabry-Perot interferometer and reconstructed time-resolved two-dimensional maps of the horizontal vector wind field to infer forward and backward air parcel trajectories over time. This is the first comprehensive study to visualize the complex motions of thermospheric air parcels carried through the actual observed local-scale structures in the high-latitude winds. Results show that thermospheric air parcel transport is a very difficult observational problem, because the trajectories followed are very sensitive to the detailed features of the driving wind field. To reconstruct the actual motion of a given air parcel requires wind measurements everywhere along the trajectory followed, with spatial resolutions of 100 km or less, and temporal resolutions of a few minutes or better. Understanding such transport is important, for example, in predicting the global-scale impacts of aurorally generated composition perturbations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5647790','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5647790">The dependence of the strength and thickness of field-aligned currents on solar wind and ionospheric parameters</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Johnson, Jay R.; Wing, Simon 2017-01-01 Sheared plasma flows at the low-latitude boundary layer (LLBL) correlate well with early afternoon auroral arcs and upward field-aligned currents. We present a simple analytic model that relates solar wind and ionospheric parameters to the strength and thickness of field-aligned currents (Λ) in a region of sheared velocity, such as the LLBL. We compare the predictions of the model with DMSP observations and find remarkably good scaling of the upward region 1 currents with solar wind and ionospheric parameters in region located at the boundary layer or open field lines at 1100–1700 magnetic local time. We demonstrate that Λ~nsw−0.5 and Λ ~ L when Λ/L < 5 where L is the auroral electrostatic scale length. The sheared boundary layer thickness (Δm) is inferred to be around 3000 km, which appears to have weak dependence on Vsw. J‖ has dependencies on Δm, Σp, nsw, and Vsw. The analytic model provides a simple way to organize data and to infer boundary layer structures from ionospheric data. PMID:29057194 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA43C..02B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA43C..02B">Large-Scale Structure and Dynamics of the Sub-Auroral Polarization Stream (SAPS)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Baker, J. B. H.; Nishitani, N.; Kunduri, B.; Ruohoniemi, J. M.; Sazykin, S. Y. 2017-12-01 The Sub-Auroral Polarization Stream (SAPS) is a narrow channel of high-speed westward ionospheric convection which appears equatorward of the duskside auroral oval during geomagnetically active periods. SAPS is generally thought to occur when the partial ring current intensifies and enhanced region-2 field-aligned currents (FACs) are forced to close across the low conductance region of the mid-latitude ionospheric trough. However, recent studies have suggested SAPS can also occur during non-storm periods, perhaps associated with substorm activity. In this study, we used measurements from mid-latitude SuperDARN radars to examine the large-scale structure and dynamics of SAPS during several geomagnetically active days. Linear correlation analysis applied across all events suggests intensifications of the partial ring current (ASYM-H index) and auroral activity (AL index) are both important driving influences for controlling the SAPS speed. Specifically, SAPS flows increase, on average, by 20-40 m/s per 10 nT of ASYM-H and 10-30 m/s per 100 nT of AL. These dependencies tend to be stronger during the storm recovery phase. There is also a strong local time dependence such that the strength of SAPS flows decrease by 70-80 m/s for each hour of local time moving from dusk to midnight. By contrast, the evidence for direct solar wind control of SAPS speed is much less consistent, with some storms showing strong correlations with the interplanetary electric field components and/or solar wind dynamic pressure, while others do not. These results are discussed in the context of recent simulation results from the Rice Convection Model (RCM). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.5139A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.5139A">Spacecraft Charging Hazards In Low-earth Orbit</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Anderson, P. C. The space environment in low-Earth orbit (LEO) has until recently been considered quite benign to high levels of spacecraft charging. However, it has been found that the DMSP spacecraft at 840 km can charge to very large negative voltages (up to - 2000 V) when encountering intense precipitating electron events (auroral arcs) while traversing the auroral zone. The occurrence frequency of charging events, defined as when the spacecraft charged to levels exceeding 100 V negative, was highly correlated with the 11-year solar cycle with the largest number of events occurring during solar minimum. This was due to the requirement that the background thermal plasma den- sity be low, at most 104 cm-2. During solar maximum, the plasma density is typically well above that level due to the solar EUV ionizing radiation, and although the oc- currence frequency of auroral arcs is considerably greater than at solar minimum, the occurrence of high-level charging is minimal. Indeed, of the over 1200 events found during the most recent solar cycle, none occurred during the last solar maximum. This has implications to a number of LEO satellite programs, including the International Space Station (ISS). The plasma density in the ISS orbit, at a much lower altitude than DMSP, is well above that at 840 km and rarely below 104 cm-2. However, in the wake of the ISS, the plasma density can be 2 orders of magnitude or more lower than the background density and thus conditions are ripe for significant charging effects. With an inclination of 51.6 degrees, the ISS does enter the auroral zone, particularly during geomagnetic storms and substorms when the auroral boundary can penetrate to very low latitudes. This has significant implications for EVA operations in the ISS wake. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100024396','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100024396">Physical Processes for Driving Ionospheric Outflows in Global Simulations</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moore, Thomas Earle; Strangeway, Robert J. 2009-01-01 We review and assess the importance of processes thought to drive ionospheric outflows, linking them as appropriate to the solar wind and interplanetary magnetic field, and to the spatial and temporal distribution of their magnetospheric internal responses. These begin with the diffuse effects of photoionization and thermal equilibrium of the ionospheric topside, enhancing Jeans' escape, with ambipolar diffusion and acceleration. Auroral outflows begin with dayside reconnexion and resultant field-aligned currents and driven convection. These produce plasmaspheric plumes, collisional heating and wave-particle interactions, centrifugal acceleration, and auroral acceleration by parallel electric fields, including enhanced ambipolar fields from electron heating by precipitating particles. Observations and simulations show that solar wind energy dissipation into the atmosphere is concentrated by the geomagnetic field into auroral regions with an amplification factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Internal plasmas thus enable electromagnetic driving via coupling to the plasma, neutral gas and by extension, the entire body " We assess the Importance of each of these processes in terms of local escape flux production as well as global outflow, and suggest methods for their implementation within multispecies global simulation codes. We complete 'he survey with an assessment of outstanding obstacles to this objective. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120002020','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120002020">Dynamic Agents of Magnetosphere-Ionosphere Coupling</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Khazanov, George V.; Rowland, Douglas E.; Moore, Thomas E.; Collier, Michael 2011-01-01 VISIONS sounding rocket mission (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) has been awarded to NASA/GSFC (PI Rowland) in order to provide the first combined remote sensing and in situ measurements of the regions where ion acceleration to above 5 e V is occurring, and of the sources of free energy and acceleration mechanisms that accelerate the ions. The key science question of VISIONS is how, when, and where, are ions accelerated to escape velocities in the auroral zone below 1000 km, following substorm onset? Sources of free energy that power this ion acceleration process include (but not limited) electron precipitation, field-aligned currents, velocity shears, and Alfvenic Poynting flux. The combine effect of all these processes on ionospheric ion outflows will be investigated in a framework of the kinetic model that has been developed by Khazanov et al. in order to study the polar wind transport in the presence of photoelectrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999DPS....31.5311S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999DPS....31.5311S">Detection of the 'continuous' H3(+) electrojet in the Jovian Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stallard, T. S.; Miller, S.; Achilleos, N.; Rego, D.; Prange, R.; Dougherty, M.; Joseph, R. D. 1999-09-01 Recently we have published the first detection of an auroral electrojet - a fast ion wind circulating around the auroral oval - on Jupiter (Rego et al., Nature, 399, 121-123). The detection was made during an unusual "auroral event", but raised the possibility that such electrojets might be detectable under "normal" auroral conditions. This work, currently in progress, is directed towards that aim. To accomplish this, high resolution infrared spectra and images of the Jovian aurora were taken on the nights of September 7-11(th) 1998, observing the nu_ {2} Q(1,0(-) ) line of H(+}_{3) at 3.953 mu m. The slit was aligned across the planet, perpendicular to the rotational axis, and the spectra were taken at 1 arcsec steps across the planet through the region of aurora. Each spectrum has been fitted row by row with a gaussian using height, width, background and central position as free parameters. This results in a measurement of how the relative central position varies across each spectra. Having processed the data, removing any systematic array effects, rotation, and instrumentally based spatial effects, we intend to show a measurable electrojet from the dopler shift it causes. This will be in the form of LOS maps of the auroral region at different CML taken over the 5 night observation period. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active">7</li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active">8</li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050215494&hterms=fluorescent+probes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dfluorescent%2Bprobes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050215494&hterms=fluorescent+probes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dfluorescent%2Bprobes">X-Ray Probes of Jupiter's Auroral Zones, Galilean Moons, and the Io Plasma Torus</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Elsner, R. F.; Ramsey, B. D.; Swartz, D. A.; Rehak, P.; Waite, J. H., Jr.; Cooper, J. F.; Johnson, R. E. 2005-01-01 Remote observations from the Earth orbiting Chandra X-ray Observatory and the XMM-Newton Observatory have shown the the Jovian system is a rich and complex source of x-ray emission. The planet's auroral zones and its disk are powerful sources of x-ray emission, though with different origins. Chandra observations discovered x-ray emission from the Io plasma torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from the moons is due to bombardment of their surfaces by highly energetic magnetospheric protons, and oxygen and sulfur ions, producing fluorescent x-ray emission lines from the elements in their surfaces against an intense background continuum. Although very faint when observed from Earth orbit, an imaging x-ray spectrometer in orbit around the icy Galilean moons would provide a detail mapping of the elemental composition in their surfaces. Here we review the results of Chandra and XMM-Newton observations of the Jovian system and describe the characteristics of X-MIME, an imaging x-ray spectrometer undergoing study for possible application to future missions to Jupiter such as JIMO. X-MIME has the ultimate goal of providing detailed high-resolution maps of the elemental abundances of the surfaces of Jupiter's icy moons and Io, as well as detailed study of the x-ray mission from the Io plasma torus, Jupiter's auroral zones, and the planetary disk. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030004238&hterms=debye+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddebye%2Blength','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030004238&hterms=debye+length&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Ddebye%2Blength">Formation of Electrostatic Potential Drops in the Auroral Zone</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Schriver, D.; Ashour-Abdalla, M.; Richard, R. L. 2001-01-01 In order to examine the self-consistent formation of large-scale quasi-static parallel electric fields in the auroral zone on a micro/meso scale, a particle in cell simulation has been developed. The code resolves electron Debye length scales so that electron micro-processes are included and a variable grid scheme is used such that the overall length scale of the simulation is of the order of an Earth radii along the magnetic field. The simulation is electrostatic and includes the magnetic mirror force, as well as two types of plasmas, a cold dense ionospheric plasma and a warm tenuous magnetospheric plasma. In order to study the formation of parallel electric fields in the auroral zone, different magnetospheric ion and electron inflow boundary conditions are used to drive the system. It has been found that for conditions in the primary (upward) current region an upward directed quasi-static electric field can form across the system due to magnetic mirroring of the magnetospheric ions and electrons at different altitudes. For conditions in the return (downward) current region it is shown that a quasi-static parallel electric field in the opposite sense of that in the primary current region is formed, i.e., the parallel electric field is directed earthward. The conditions for how these different electric fields can be formed are discussed using satellite observations and numerical simulations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM41A2663L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM41A2663L">The Isinglass Auroral Sounding Rocket Campaign: data synthesis incorporating remote sensing, in situ observations, and modelling</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lynch, K. A.; Clayton, R.; Roberts, T. M.; Hampton, D. L.; Conde, M.; Zettergren, M. D.; Burleigh, M.; Samara, M.; Michell, R.; Grubbs, G. A., II; Lessard, M.; Hysell, D. L.; Varney, R. H.; Reimer, A. 2017-12-01 The NASA auroral sounding rocket mission Isinglass was launched from Poker Flat Alaska in winter 2017. This mission consists of two separate multi-payload sounding rockets, over an array of groundbased observations, including radars and filtered cameras. The science goal is to collect two case studies, in two different auroral events, of the gradient scale sizes of auroral disturbances in the ionosphere. Data from the in situ payloads and the groundbased observations will be synthesized and fed into an ionospheric model, and the results will be studied to learn about which scale sizes of ionospheric structuring have significance for magnetosphere-ionosphere auroral coupling. The in situ instrumentation includes thermal ion sensors (at 5 points on the second flight), thermal electron sensors (at 2 points), DC magnetic fields (2 point), DC electric fields (one point, plus the 4 low-resource thermal ion RPA observations of drift on the second flight), and an auroral precipitation sensor (one point). The groundbased array includes filtered auroral imagers, the PFISR and SuperDarn radars, a coherent scatter radar, and a Fabry-Perot interferometer array. The ionospheric model to be used is a 3d electrostatic model including the effects of ionospheric chemistry. One observational and modelling goal for the mission is to move both observations and models of auroral arc systems into the third (along-arc) dimension. Modern assimilative tools combined with multipoint but low-resource observations allow a new view of the auroral ionosphere, that should allow us to learn more about the auroral zone as a coupled system. Conjugate case studies such as the Isinglass rocket flights allow for a test of the models' intepretation by comparing to in situ data. We aim to develop and improve ionospheric models to the point where they can be used to interpret remote sensing data with confidence without the checkpoint of in situ comparison. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998GeoRL..25.2041E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998GeoRL..25.2041E">FAST satellite observations of large-amplitude solitary structures</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ergun, R. E.; Carlson, C. W.; McFadden, J. P.; Mozer, F. S.; Delory, G. T.; Peria, W.; Chaston, C. C.; Temerin, M.; Roth, I.; Muschietti, L.; Elphic, R.; Strangeway, R.; Pfaff, R.; Cattell, C. A.; Klumpar, D.; Shelley, E.; Peterson, W.; Moebius, E.; Kistler, L. We report observations of “fast solitary waves” that are ubiquitous in downward current regions of the mid-altitude auroral zone. The single-period structures have large amplitudes (up to 2.5 V/m), travel much faster than the ion acoustic speed, carry substantial potentials (up to ∼100 Volts), and are associated with strong modulations of energetic electron fluxes. The amplitude and speed of the structures distinguishes them from ion-acoustic solitary waves or weak double layers. The electromagnetic signature appears to be that of an positive charge (electron hole) traveling anti-earthward. We present evidence that the structures are in or near regions of magnetic-field-aligned electric fields and propose that these nonlinear structures play a key role in supporting parallel electric fields in the downward current region of the auroral zone. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830059908&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DElectric%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830059908&hterms=Electric+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DElectric%2Bcurrent">The relationship of total Birkeland currents to the merging electric field</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bythrow, P. F.; Potemra, T. A. 1983-01-01 Magsat data were used to examine the behavior of Birkeland currents during 1100-2000 UT in consecutive orbits passing near the dawn-dusk meridian. The field was measured with a three-axis fluxgate instrument with a resolution of within 0.5 nT, with the sampling occurring every 1/16th sec. A total of 32 crossings of the Northern Hemisphere auroral zone were available for analysis. The changes in the magnetic readings were correlated more closely with variation in the IMF parameters than to the latitudinal width of the changes. Evidence was found for a relationship between the reconnection electric field and the intensity of the large-scale Birkeland current system. The total conductance of the auroral zone was calculated to be about 18.7 mhos. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19980236879&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19980236879&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwind%2Bmonitor">Comparisons of Solar Wind Coupling Parameters with Auroral Energy Deposition Rates</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Elsen, R.; Brittnacher, M. J.; Fillingim, M. O.; Parks, G. K.; Germany G. A.; Spann, J. F., Jr. 1997-01-01 Measurement of the global rate of energy deposition in the ionosphere via auroral particle precipitation is one of the primary goals of the Polar UVI program and is an important component of the ISTP program. The instantaneous rate of energy deposition for the entire month of January 1997 has been calculated by applying models to the UVI images and is presented by Fillingim et al. In this session. A number of parameters that predict the rate of coupling of solar wind energy into the magnetosphere have been proposed in the last few decades. Some of these parameters, such as the epsilon parameter of Perrault and Akasofu, depend on the instantaneous values in the solar wind. Other parameters depend on the integrated values of solar wind parameters, especially IMF Bz, e.g. applied flux which predicts the net transfer of magnetic flux to the tail. While these parameters have often been used successfully with substorm studies, their validity in terms of global energy input has not yet been ascertained, largely because data such as that supplied by the ISTP program was lacking. We have calculated these and other energy coupling parameters for January 1997 using solar wind data provided by WIND and other solar wind monitors. The rates of energy input predicted by these parameters are compared to those measured through UVI data and correlations are sought. Whether these parameters are better at providing an instantaneous rate of energy input or an average input over some time period is addressed. We also study if either type of parameter may provide better correlations if a time delay is introduced; if so, this time delay may provide a characteristic time for energy transport in the coupled solar wind-magnetosphere-ionosphere system. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990113191&hterms=energy+regions+Remote&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Denergy%2Bregions%2BRemote','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990113191&hterms=energy+regions+Remote&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Denergy%2Bregions%2BRemote">Remote Determination of Auroral Energy Characteristics During Substorm Activity</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Germany, G. A.; Parks, G. K.; Brittnacher, M. J.; Cumnock, J.; Lummerzheim, D.; Spann, J. F., Jr. 1997-01-01 Ultraviolet auroral images from the Ultraviolet Imager onboard the POLAR satellite can be used as quantitative remote diagnostics of the auroral regions, yielding estimates of incident energy characteristics, compositional changes, and other higher order data products. In particular, images of long and short wavelength N2 Lyman-Birge-Hopfield (LBH) emissions can be modeled to obtain functions of energy flux and average energy that are basically insensitive to changes in seasonal and solar activity changes. This technique is used in this study to estimate incident electron energy flux and average energy during substorm activity occurring on May 19, 1996. This event was simultaneously observed by WIND, GEOTAIL, INTERBALL, DMSP and NOAA spacecraft as well as by POLAR. Here incident energy estimates derived from Ultraviolet Imager (UVI) are compared with in situ measurements of the same parameters from an overflight by the DMSP F12 satellite coincident with the UVI image times. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050201880&hterms=heating+global&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dheating%2Bglobal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050201880&hterms=heating+global&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dheating%2Bglobal">Jupiter Thermospheric General Circulation Model (JTGCM): Global Structure and Dynamics Driven by Auroral and Joule Heating</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bougher, S. W.; J. Il. Waite, Jr.; Majeed, T. 2005-01-01 A growing multispectral database plus recent Galileo descent measurements are being used to construct a self-consistent picture of the Jupiter thermosphere/ionosphere system. The proper characterization of Jupiter s upper atmosphere, embedded ionosphere, and auroral features requires the examination of underlying processes, including the feedbacks of energetics, neutral-ion dynamics, composition, and magnetospheric coupling. A fully 3-D Jupiter Thermospheric General Circulation Model (JTGCM) has been developed and exercised to address global temperatures, three-component neutral winds, and neutral-ion species distributions. The domain of this JTGCM extends from 20-microbar (capturing hydrocarbon cooling) to 1.0 x 10(exp -4) nbar (including aurora/Joule heating processes). The resulting JTGCM has been fully spun-up and integrated for greater than or equal to40 Jupiter rotations. Results from three JTGCM cases incorporating moderate auroral heating, ion drag, and moderate to strong Joule heating processes are presented. The neutral horizontal winds at ionospheric heights vary from 0.5 km/s to 1.2 km/s, atomic hydrogen is transported equatorward, and auroral exospheric temperatures range from approx.1200-1300 K to above 3000 K, depending on the magnitude of Joule heating. The equatorial temperature profiles from the JTGCM are compared with the measured temperature structure from the Galileo AS1 data set. The best fit to the Galileo data implies that the major energy source for maintaining the equatorial temperatures is due to dynamical heating induced by the low-latitude convergence of the high-latitude-driven thermospheric circulation. Overall, the Jupiter thermosphere/ionosphere system is highly variable and is shown to be strongly dependent on magnetospheric coupling which regulates Joule heating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A23I3366N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A23I3366N">An Ad-hoc Satellite Network to Measure Filamentary Current Structures in the Auroral Zone</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nabong, C.; Fritz, T. A.; Semeter, J. L. 2014-12-01 An ad-hoc cubesat-based satellite network project known as ANDESITE is under development at Boston University. It aims to develop a dense constellation of easy-to-use, rapidly-deployable low-cost wireless sensor nodes in space. The objectives of the project are threefold: 1) Demonstrate viability of satellite based sensor networks by deploying an 8-node miniature sensor network to study the filamentation of the field aligned currents in the auroral zones of the Earth's magnetosphere. 2) Test the scalability of proposed protocols, including localization techniques, tracking, data aggregation, and routing, for a 3 dimensional wireless sensor network using a "flock" of nodes. 3) Construct a 6U Cube-sat running the Android OS as an integrated constellation manager, data mule and sensor node deplorer. This small network of sensor nodes will resolve current densities at different spatial resolutions in the near-Earth magnetosphere using measurements from magnetometers with 1-nT sensitivities and 0.2 nT/√Hz self-noise. Mapping of these currents will provide new constraints for models of auroral particle acceleration, wave-particle interactions, ionospheric destabilization, and other kinetic processes operating in the low-beta plasma of the near Earth magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800016210&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwind%2Bmonitor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800016210&hterms=wind+monitor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwind%2Bmonitor">Solar wind and magnetosphere interactions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Russell, C. T.; Allen, J. H.; Cauffman, D. P.; Feynman, J.; Greenstadt, E. W.; Holzer, R. E.; Kaye, S. M.; Slavin, J. A.; Manka, R. H.; Rostoker, G. 1979-01-01 The relationship between the magnetosphere and the solar wind is addressed. It is noted that this interface determines how much of the solar plasma and field energy is transferred to the Earth's environment, and that this coupling not only varies in time, responding to major solar disturbances, but also to small changes in solar wind conditions and interplanetary field directions. It is recommended that the conditions of the solar wind and interplanetary medium be continuously monitored, as well as the state of the magnetosphere. Other recommendations include further study of the geomagnetic tail, tests of Pc 3,4 magnetic pulsations as diagnostics of the solar wind, and tests of kilometric radiation as a remote monitor of the auroral electrojet. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850009419','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850009419">A research in support of NASA's space science</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hanson, W. B. 1985-01-01 Thirty-nine papers on cosmic ray anisotropies, law energy auroral particles, helium and hydrogen airglow, ionospheric irregularities, thermospheric winds, interhemisphere ion transport, ion cyclotron heating, ion temperature morphology, ion chemistry, ion convection, and spacecraft interactions with the atmosphere and ionosphere are described. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015HGSS....6...23A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015HGSS....6...23A">Paradigm transitions in solar-terrestrial physics from 1900: my personal view</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Akasofu, S.-I. 2015-04-01 Solar-terrestrial physics, like any other scientific field, has evolved and developed by replacing older theories with newer theories. Unfortunately, each generation of young researchers tends to learn naturally only the latest, and perhaps the most popular theory and believes that it is the only useful one to pursue. Therefore, they do not necessarily realize that in the past the theory they chose had struggled to reach its presently acceptable state, and that eventually it might be replaced with a new theory. Two generations of scientists or in some subjects even more generations tend to be guided by one particular idea or theory. Thus, among us (namely, one or two generations) a high degree of agreement occurs, both on the theoretical assumptions and on the problem to be solved within the framework provided by the theory. Such an idea or theory was termed paradigm by Kuhn (1970). The purpose of this article is to describe several examples of the transition of paradigms and ideas in the subjects of solar-terrestrial physics. The examples are subjects that experienced a paradigm change after prevailing in the field for a few generations and also some that are perhaps on the verge of the transition. The chosen subjects are (1) Stormer's single particle theory to Chapman's plasma theory (1907-1963), (2) the auroral zone to the auroral oval (1860-1971), (3) the closed to open magnetosphere (1931-1971), (4) the current system controversies (1918-1963) and (1964-present), (5) the fixed pattern concept to the concept of auroral/magnetospheric substorms (1935-1982), (6) the importance of the interplanetary magnetic field (IMF) in the development of geomagnetic storms (1905-1966), (7) the ring current: solar wind protons to oxygen ions from the ionosphere (1933-1977), (8) the storm-substorm controversy (1963-present), (9) substorm onset (1964-present), (10) solar flares (1958-present) and (11) sunspots (1961-present). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM44A..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM44A..07S">The Role of Superthermal Electrons in the Formation of Double Layers and their Application in Space Plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Singh, N. 2014-12-01 It is now widely recognized that superthermal electrons commonly exist with the thermal population in most space plasmas. When plasmas consisting of such electron population expand, double layers (DLs) naturally forma due to charge separation; the more mobile superthermal electrons march ahead of the thermal population, leaving a positive charge behind and generating electric fields. Under certain conditions such fields evolve into thin double layers or shocks. The double layers accelerate ions. Such double-layer formation was first invoked to explain expansion of laser produced plasmas. Since then it has been studied in laboratory experiments, and applied to (i) polar wind acceleration,(ii) the existence of low-altitude double layers in the auroral acceleration, (iii) a possible mechanism for the origination of the solar wind, (iv) the helicon double layer thrusters, and (v) the deceleration of electrons after their acceleration in solar flare events. The role of superthermal-electron driven double layers, also known as the low-altitude auroral double layers in the upward current region, in the upward acceleration of ionospheric ions is well-known. In the auroral application the upward moving superthermal electrons consist of backscattered downgoing primary energetic electrons as well as the secondary electrons. Similarly we suggest that such double layers might play roles in the acceleration of ions in the solar wind across the coronal transition region, where the superthermal electrons are supplied by magnetic reconnection events. We will present a unified theoretical view of the superthermal electron-driven double layers and their applications. We will summarize theoretical, experimental, simulation and observational results highlighting the common threads running through the various existing studies. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AnGeo..36..205M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AnGeo..36..205M">Cross-correlation and cross-wavelet analyses of the solar wind IMF Bz and auroral electrojet index AE coupling during HILDCAAs</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Marques de Souza, Adriane; Echer, Ezequiel; José Alves Bolzan, Mauricio; Hajra, Rajkumar 2018-02-01 Solar-wind-geomagnetic activity coupling during high-intensity long-duration continuous AE (auroral electrojet) activities (HILDCAAs) is investigated in this work. The 1 min AE index and the interplanetary magnetic field (IMF) Bz component in the geocentric solar magnetospheric (GSM) coordinate system were used in this study. We have considered HILDCAA events occurring between 1995 and 2011. Cross-wavelet and cross-correlation analyses results show that the coupling between the solar wind and the magnetosphere during HILDCAAs occurs mainly in the period ≤ 8 h. These periods are similar to the periods observed in the interplanetary Alfvén waves embedded in the high-speed solar wind streams (HSSs). This result is consistent with the fact that most of the HILDCAA events under present study are related to HSSs. Furthermore, the classical correlation analysis indicates that the correlation between IMF Bz and AE may be classified as moderate (0.4-0.7) and that more than 80 % of the HILDCAAs exhibit a lag of 20-30 min between IMF Bz and AE. This result corroborates with Tsurutani et al. (1990) where the lag was found to be close to 20-25 min. These results enable us to conclude that the main mechanism for solar-wind-magnetosphere coupling during HILDCAAs is the magnetic reconnection between the fluctuating, negative component of IMF Bz and Earth's magnetopause fields at periods lower than 8 h and with a lag of about 20-30 min. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GSL.....3...12M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GSL.....3...12M">Relation of the auroral substorm to the substorm current wedge</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> McPherron, Robert L.; Chu, Xiangning 2016-12-01 The auroral substorm is an organized sequence of events seen in the aurora near midnight. It is a manifestation of the magnetospheric substorm which is a disturbance of the magnetosphere brought about by the solar wind transfer of magnetic flux from the dayside to the tail lobes and its return through the plasma sheet to the dayside. The most dramatic feature of the auroral substorm is the sudden brightening and poleward expansion of the aurora. Intimately associated with this expansion is a westward electrical current flowing across the bulge of expanding aurora. This current is fed by a downward field-aligned current (FAC) at its eastern edge and an upward current at its western edge. This current system is called the substorm current wedge (SCW). The SCW forms within a minute of auroral expansion. FAC are created by pressure gradients and field line bending from shears in plasma flow. Both of these are the result of pileup and diversion of plasma flows in the near-earth plasma sheet. The origins of these flows are reconnection sites further back in the tail. The auroral expansion can be explained by a combination of a change in field line mapping caused by the substorm current wedge and a tailward growth of the outer edge of the pileup region. We illustrate this scenario with a complex substorm and discuss some of the problems associated with this interpretation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850052710&hterms=Biddle&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBiddle','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850052710&hterms=Biddle&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBiddle">Auroral zone effects on hydrogen geocorona structure and variability</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moore, T. E.; Biddle, A. P.; Waite, J. H., Jr.; Killeen, T. L. 1985-01-01 The effect of diurnal and magnetospheric modulations on the structure of the hydrogen geocorona is analyzed on the basis of recent observations. Particular attention is given to the enhancement of neutral escape by plasma effects, including the recently observed phenomenon of low-altitude ion acceleration. It is found that, while significant fluxes of neutral H should be produced by transverse ion acceleration in the auroral zone, the process is probably insufficient to account for the observed polar depletion of hydrogen atoms. Analysis of recent exospheric temperature measurements from the Dynamics Explorer-2 satellite suggest that neutral heating in and near the high latitude cusp may be the major contributor to depleted atomic hydrogen densities at high latitudes. Altitude profiles of the production rates for escaping neutral hydrogen atoms during periods of maximum, minimum, and typical solar activity are provided. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMSM12A..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMSM12A..06M">Simulating the Fate of an Ionospheric Mass Ejection</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Moore, T. E.; Fok, M. H.; Delcourt, D. C.; Slinker, S. P.; Fedder, J. A. 2008-12-01 We report global ion kinetic (GIK) simulations of the 24-25 Sep 1998 storm, with all relevant ionospheric outflows including polar, auroral, and plasmaspheric winds. This storm included substantial periods of northward interplanetary magnetic field, but did develop a Dst of -200 nT at its peak. The solar disturbance resulted form a coronal mass ejection that reached a peak dynamic pressure at the magnetosphere of 6.2 nPa, and produced a substantial enhancement of auroral wind oxygen outflow from the dayside, which has been termed an "ionospheric mass ejection" in an earlier observational paper. We use the LFM global simulation model to produce electric and magnetic fields in the outer magnetosphere, the Strangeway-Zheng outflow scalings with Delcourt ion trajectories to include ionospheric outflows, and the Fok-Ober inner magnetospheric model for the plasmaspheric and ring current response to all particle populations. We assess the combined contributions of heliospheric and geospheric plasmas to the ring current for this event. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.8153B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.8153B">SMILE: A new approach to exploring solar-terrestrial relationships</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Branduardi-Raymont, Graziella; Wang, Chi; Steven, Sembay; Dai, Lei; Li, Lei; Donovan, Eric; Sun, Tianran; Kataria, Dhiren; Yang, Huigen; Read, Andrew; Whittaker, Ian; Spanswick, Emma; Sibeck, David; Kuntz, Kip; Escoubet, Philippe; Agnolon, David; Raab, Walfried; Zheng, Janhua 2017-04-01 SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) aims to investigate the coupling of the solar wind with the Earth's magnetosphere, and the geospace dynamics that ensue, in a novel and global manner never tried so far. From a highly elliptical and highly inclined polar orbit, SMILE will simultaneously image the soft X-rays produced by solar wind charge exchange to delineate the Earth's magnetic boundaries and polar cusps, image the northern auroral oval in ultraviolet emissions, and measure the solar wind/magnetosheath plasma and magnetic field input. SMILE measurements will inform the science underpinning our still limited understanding of solar-terrestrial relationships and of their fundamental drivers, and will validate both global empirical and first-principle models. For the first time we will be able to trace and link the processes governing magnetopause interactions to those causing charged particle precipitation into the cusps and the remainder of the auroral oval, mapping aspects of the global interaction including the evolution of energy and mass transport. SMILE is a joint space mission between the European Space Agency and the Chinese Academy of Sciences due for launch at the end of 2021. This presentation will cover the science that will be delivered by SMILE and will provide an overview of SMILE's payload and mission development, demonstrating the scientific potential of SMILE through simulations of the data that it will return. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850014173','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850014173">Auroral-polar cap environment and its impact on spacecraft plasma interactions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Garrett, H. B. 1985-01-01 The high density of the plasma at shuttle altitude is likely to increase greatly the possibility of arcing and shorting of exposed high voltage surfaces. For military missions over the polar caps and through the auoroal zones, the added hazards of high energy auroral particle fluxes or solar flares will further increase the hazard to shuttle, its crew, and its mission. A review of the role that the auroral and polar cap environment play in causing these interactions was conducted. A simple, though comprehensive attempt at modelling the shuttle environment at 400 km will be described that can be used to evaluate the importance of the interactions. The results of this evaluation are then used to define areas where adequate environmental measurements will be necessary if a true spacecraft interactions technology is to be developed for the shuttle. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870026476&hterms=circuit+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcircuit%2Belectric','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870026476&hterms=circuit+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcircuit%2Belectric">Simulation of double layers in a model auroral circuit with nonlinear impedance</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Smith, R. A. 1986-01-01 A reduced circuit description of the U-shaped potential structure of a discrete auroral arc, consisting of the flank transmission line plus parallel-electric-field region, is used to provide the boundary condition for one-dimensional simulations of the double-layer evolution. The model yields asymptotic scalings of the double-layer potential, as a function of an anomalous transport coefficient alpha and of the perpendicular length scale l(a) of the arc. The arc potential phi(DL) scales approximately linearly with alpha, and for alpha fixed phi (DL) about l(a) to the z power. Using parameters appropriate to the auroral zone acceleration region, potentials of phi (DPL) 10 kV scale to projected ionospheric dimensions of about 1 km, with power flows of the order of magnitude of substorm dissipation rates. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active">8</li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active">9</li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.7308A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.7308A">Characteristics of spacecraft charging in low Earth orbit</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Anderson, Phillip C. 2012-07-01 It has been found that the DMSP spacecraft at 840 km can charge to very large negative voltages (up to -2000 V) when encountering intense precipitating electron events (auroral arcs). We present an 11-year study of over 1600 charging events, defined as when the spacecraft charged to levels exceeding 100 V negative during an auroral crossing. The occurrence frequency of events was highly correlated with the 11-year solar cycle with the largest number of events occurring during solar minimum. This was due to the requirement that the background thermal plasma density be low, at most 104 cm-3. During solar maximum, the plasma density is typically well above that level due to the solar EUV ionizing radiation, and although the occurrence frequency of auroral arcs is considerably greater than at solar minimum, the occurrence of high-level charging is minimal. As a result of this study, we produced a model spectrum for precipitating electrons that can be used as a specification for the low-altitude auroral charging environment. There are implications from this study on a number of LEO satellite programs, including the International Space Station, which does enter the auroral zone, particularly during geomagnetic activity when the auroral boundary can penetrate to very low latitudes. The plasma density in the ISS orbit is usually well above the minimum required density for charging. However, in the wake of the ISS, the plasma density can be 2 orders of magnitude or more lower than the background density and thus conditions are ripe for charging. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.1664K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.1664K">Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean, earthquakes and etc). The study was supported by a grant of RFBR, n 06-05-64998. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA212206','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA212206">International Arctic Research Programs</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1989-07-01 beryllium graphite - (moonstone) cerium marble garnet chrniun ol ivine gronlandite copper phosphorus jasper gold soapstone kornerupine iron sulphur...Green- from the magnetic pole to the auroral zone. landic sea under marginal conditions where Besides these groundbased activities, mea- surements of </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750016137','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750016137">Electron precipitation in the post midnight sector of the auroral zones. [on the Explorer 40 satellite</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Frank, L. A.; Saflekos, N. A.; Ackerson, K. L. 1975-01-01 Comprehensive measurements of the angular distributions and energy spectra of electron intensities with electrostatic analyzer arrays on board the low-altitude satellite Injun 5 are reported. These are for the post-midnight sector of the auroral zones during the high-intensity events accompanying magnetic substorms. Precipitation features on closed terrestrial field lines well equatorward of the trapping boundary for energetic electrons with E greater than 45 keV were examined. No evidences of maxima in the differential energy spectra or of strongly field-aligned currents which are indicative of quasi-static electric fields aligned parallel to the geomagnetic field were found. Precipitation of low-energy electron intensities fluctuated on time scales greater than 2 seconds as viewed at the satellite position. This precipitation was characterized by isotropy for all pitch angles outside the atmospheric backscatter cone. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740020969&hterms=Wave+Energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DWave%2BEnergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740020969&hterms=Wave+Energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DWave%2BEnergy">The aurora as a source of planetary-scale waves in the middle atmosphere. [atmospheric turbulence caused by auroral energy absorption</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chiu, Y. T.; Straus, J. M. 1974-01-01 Photographs of global scale auroral forms taken by scanning radiometers onboard weather satellites in 1972 show that auroral bands exhibit well organized wave motion with typical zonal wave number of 5 or so. The scale size of these waves is in agreement with that of well organized neutral wind fields in the 150- to 200-km region during the geomagnetic storm of May 27, 1967. Further, the horizontal scale size revealed by these observations are in agreement with that of high altitude traveling ionospheric disturbances. It is conjectured that the geomagnetic storm is a source of planetary and synoptic scale neutral atmospheric waves in the middle atmosphere. Although there is, at present, no observation of substorm related waves of this scale size at mesospheric and stratospheric altitudes, the possible existence of a new source of waves of the proper scale size to trigger instabilities in middle atmospheric circulation systems may be significant in the study of lower atmospheric response to geomagnetic activity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA202423','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA202423">Media Effects on Electronic Systems in the High Latitude Region</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1988-09-01 oval and auroral electron densities. Essentially the ICED model is still based on a set of coefficients, but these are modified by other inputs. There...and larger. At the distance of the Earth’s orbit the speed of the solar wind is usually between 200 and 700 or 800 km s -1 , on which is superimposed a...magnetometer on IMP-I (the Interplanetary Monitoring Platform), an eccentric orbit satellite with apogee at 32 RE Although the solar wind flows out almost </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170006548&hterms=tourism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtourism','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170006548&hterms=tourism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtourism">Space Weather Products and Tools Used in Auroral Monitoring and Forecasting at CCMC/SWRC</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Zheng, Yihua; Rastaetter, Lutz 2015-01-01 Key points discussed in this chapter are (1) the importance of aurora research to scientific advances and space weather applications, (2) space weather products at CCMC that are relevant to aurora monitoring and forecasting, and (3) the need for more effort from the whole community to achieve a better and long-lead-time forecast of auroral activity. Aurora, as manifestations of solar wind-magnetosphere-ionosphere coupling that occurs in a region of space that is relatively easy to access for sounding rockets, satellites, and other types of observational platforms, serves as a natural laboratory for studying the underlying physics of the complex system. From a space weather application perspective, auroras can cause surface charging of technological assets passing through the region, result in scintillation effects affecting communication and navigation, and cause radar cluttering that hinders military and civilian applications. Indirectly, an aurora and its currents can induce geomagnetically induced currents (GIC) on the ground, which poses major concerns for the wellbeing and operation of power grids, particularly during periods of intense geomagnetic activity. In addition, accurate auroral forecasting is desired for auroral tourism. In this chapter, we first review some of the existing auroral models and discuss past validation efforts. Such efforts are crucial in transitioning a model(s) from research to operations and for further model improvement and development that also benefits scientific endeavors. Then we will focus on products and tools that are used for auroral monitoring and forecasting at the Space Weather Research Center (SWRC). As part of the CCMC (Community Coordinated Modeling Center), SWRC has been providing space weather services since 2010. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.4398K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.4398K">Polar cap potential saturation during the Bastille Day storm event using global MHD simulation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kubota, Y.; Nagatsuma, T.; Den, M.; Tanaka, T.; Fujita, S. 2017-04-01 We investigated the temporal variations and saturation of the cross polar cap potential (CPCP) in the Bastille Day storm event (15 July 2000) by global magnetohydrodynamics (MHD) simulation. The CPCP is considered to depend on the electric field and dynamic pressure of the solar wind as well as on the ionospheric conductivity. Previous studies considered only the ionospheric conductivity due to solar extreme ultraviolet (EUV) variations. In this paper, we dealt with the changes in the CPCP attributable to auroral conductivity variations caused by pressure enhancement in the inner magnetosphere owing to energy injection from the magnetosphere because the energy injection is considerably enhanced in a severe magnetic storm event. Our simulation reveals that the auroral conductivity enhancement is significant for the CPCP variation in a severe magnetic storm event. The numerical results concerning the Bastille Day event show that the ionospheric conductivity averaged over the auroral oval is enhanced up to 18 mho in the case of Bz of less than -59 nT. On the other hand, the average conductivity without the auroral effect is almost 6 mho throughout the entire period. Resultantly, the saturated CPCP is about 240 kV in the former and 704 kV in the latter when Bz is -59 nT. This result indicates that the CPCP variations could be correctly reproduced when the time variation of auroral conductivity caused by pressure enhancement due to the energy injection from the magnetosphere is correctly considered in a severe magnetic storm event. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970026973','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970026973">The Visible Imaging System (VIS) for the Polar Spacecraft</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Frank, L. A.; Sigwarth, J. B.; Craven, J. D.; Cravens, J. P.; Dolan, J. S.; Dvorsky, M. R.; Hardebeck, P. K.; Harvey, J. D.; Muller, D. W. 1995-01-01 The Visible Imaging System (VIS) is a set of three low-light-level cameras to be flown on the POLAR spacecraft of the Global Geospace Science (GGS) program which is an element of the International Solar-Terrestrial Physics (ISTP) campaign. Two of these cameras share primary and some secondary optics and are designed to provide images of the nighttime auroral oval at visible wavelengths. A third camera is used to monitor the directions of the fields-of-view of these sensitive auroral cameras with respect to sunlit Earth. The auroral emissions of interest include those from N+2 at 391.4 nm, 0 I at 557.7 and 630.0 nm, H I at 656.3 nm, and 0 II at 732.0 nm. The two auroral cameras have different spatial resolutions. These resolutions are about 10 and 20 km from a spacecraft altitude of 8 R(sub e). The time to acquire and telemeter a 256 x 256-pixel image is about 12 s. The primary scientific objectives of this imaging instrumentation, together with the in-situ observations from the ensemble of ISTP spacecraft, are (1) quantitative assessment of the dissipation of magnetospheric energy into the auroral ionosphere, (2) an instantaneous reference system for the in-situ measurements, (3) development of a substantial model for energy flow within the magnetosphere, (4) investigation of the topology of the magnetosphere, and (5) delineation of the responses of the magnetosphere to substorms and variable solar wind conditions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA41B2619L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA41B2619L">Driving of Dramatic Geomagnetic Activity by Enhancement of Meso-Scale Polar-cap Flows</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lyons, L. R.; Gallardo-Lacourt, B.; Zou, Y.; Nishimura, Y.; Anderson, P. C.; Angelopoulos, V.; Ruohoniemi, J. M.; Mitchell, E. J.; Paxton, L. J.; Nishitani, N. 2017-12-01 Recent studies have shown that mesoscale flows are common within the polar cap ionosphere. They often cross the magnetic separatrix, and become are critical to the driving of geomagnetic activity. They lead, for example, to plasma sheet flow bursts, auroral poleward boundary intensifications, auroral streamers, substorms, auroral omega bands, and poleward motion of the polar cap boundary from reconnection. We have found large enhancements of these meso-scale ionospheric polar cap flows heading towards the nightside separatrix. These enhancements are common immediately after the impact of CME shocks under southward IMF, but can also occur in other situations, including without substantial change in the solar wind or IMF. These meso-scale flow enhancements, which must extent outward along magnetospheric field lines from the ionosphere, are seen to drive an almost immediate strong auroral, ionospheric and field-aligned current, and reconnection activity. The resulting activity is particularly dramatic during the initiation of CME storms, but may reflect a more generally occurring phenomenon of mesoscale flow enhancements leading to similar oval responses without a shock impact, including during and following the expansion phase some substorms. If this phenomenon is indeed common, it could lead to possibly fundamental questions, such as when do polar cap convection enhancements lead to a substorm growth phase versus leading directly to strong poleward expansion of, and strong activity within, the auroral oval field line region? Another critical question would be what leads to and causes the enhancements in meso-scale polar cap flows? </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA42B..04W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA42B..04W">Sources, properties, and energization of auroral particle precipitation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wing, S.; Johnson, J.; Khazanov, G. V. 2017-12-01 The sources of and the physical processes associated with the auroral ion and electron precipitation are studied with DMSP satellites. The electron aurora has been previously classified into three categories: diffuse, monoenergetic, and broadband aurorae. The diffuse auroral electrons can be observed mainly in 22:00 - 09:00 MLT, which coincides much with the spatial distribution of the whistler-mode chorus waves that have been shown to be the predominant mechanism for pitch-angle scattering magnetospheric electrons into the loss cone, but there appears to be a separate population near noon, which may be associated with solar wind particles. The broadband auroral electrons can be found mostly at 22:00 - 02:00 MLT and pre-noon where Alfvén waves, which cause broadband electron acceleration, are observed in the magnetosphere. On the other hand, the monoenergetic auroral electrons can be observed at dusk-midnight sector, pre- and post-noon. The monoenergetic electrons have been previously thought as magnetospheric electrons that have gone through a quasi-static parallel electric field in the upward field-aligned current regions. However, there may be a connection between monoenergetic and broadband electrons in that the low frequency Alfvén wave-electron interaction can result in monoenergetic electron signature. This is consistent with the observations where broadband and monoenergetic electrons are often spatially co-located. Precipitating electrons can ionize the neutrals in the ionosphere, which can travel upward, which can precipitate in the opposite hemisphere or reflected back to the same hemisphere by upward field-aligned potential drop. Either way, the upward flowing electrons can greatly modify the initial precipitating electron population. Substorm processes increase the power of the diffuse, monoenergetic, and broadband electron aurora by 310%, 71%, and 170%, respectively. Substorms energize the ion aurora mainly in the 21:00-05:00 MLT sector. The duration of the substorm cycle for monoenergetic and broadband auroral is 5 hr, but it is larger than 5 hr for diffuse auroral electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA43C..04C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA43C..04C">The Effect of Neutral Winds on Simulated Inner Magnetospheric Electric Fields During the 17 March 2013 Storm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chen, M.; Lemon, C.; Walterscheid, R. L.; Hecht, J. H.; Sazykin, S. Y.; Wolf, R. 2017-12-01 We investigate how neutral winds and particle precipitation affect the simulated development of electric fields including Sub-Auroral Polarization Streams (SAPS) during the 17 March 2013 storm. Our approach is to use the magnetically and electrically self-consistent Rice Convection Model - Equilibrium (RCM-E) to simulate the inner magnetospheric electric field. We use parameterized rates of whistler-generated electron pitch-angle scattering from Orlova and Shprits [JGR, 2014] that depend on equatorial radial distance, magnetic activity (Kp), and magnetic local time (MLT) outside the simulated plasmasphere. Inside the plasmasphere, parameterized scattering rates due to hiss [Orlova et al., GRL, 2014] are used. Ions are scattered at a fraction of strong pitch-angle scattering where the fraction is scaled by epsilon, the ratio of the gyroradius to the field-line radius of curvature, when epsilon is greater than 0.1. The electron and proton contributions to the auroral conductance in the RCM-E are calculated using the empirical Robinson et al. [JGR, 1987] and Galand and Richmond [JGR, 2001] equations, respectively. The "background" ionospheric conductance is based on parameters from the International Reference Ionosphere [Bilitza and Reinisch, JASR, 2008] but modified to include the effect of specified ionospheric troughs. Neutral winds are modeled by the empirical Horizontal Wind Model (HWM07) in the RCM-E. We compare simulated precipitating particle energy flux, E x B velocities with DMSP observations during the 17 March 2013 storm with and without the inclusion of neutral winds. Discrepancies between the simulations and observations will aid us in assessing needed improvements in the model. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSA31B2344B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSA31B2344B">Auroral LSTIDs and SAR Arc Occurrences in Northern California During Geomagnetic Storms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bhatt, A.; Kendall, E. A. 2015-12-01 A 630nm allsky imager has been operated for two years in northern California at the Hat Creek Radio Observatory. F-region airglow data captured by the imager ranges from approximately L=1.7 -2.7. Since installation of the imager several geomagnetic storms have occurred with varying intensities. Two main manifestations of the geomagnetic storms are observed in the 630 nm airglow data: large-scale traveling ionospheric disturbances that are launched from the auroral zone and Stable Auroral Red (SAR) arcs during more intense geomagnetic storms. We will present a statistical analysis of these storm-time phenomena in northern California for the past eighteen months. This imager is part of a larger all-sky imaging network across the continental United States, termed MANGO (Midlatitude All-sky-imaging Network for Geophysical Observations). Where available, we will add data from networked imagers located at similar L-shell in other states as well. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSA33A1447G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSA33A1447G">Generation of Traveling Atmospheric Disturbances During a Pulsating Geomagnetic Storm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gardner, L. C.; Schunk, R. W. 2009-12-01 Traveling Atmospheric Disturbances (TAD’s) are studied with a 3-D high-resolution (1°x3°) global thermosphere/ionosphere model to determine the importance of the high-latitude production mechanisms contained in the model. The possible production mechanisms are the oval size, the precipitating electron characteristic energy and energy flux, and the cross polar cap potential. The production mechanisms are pulsed at a one-hour period, as was observed in a recent long-duration geomagnetic storm. With auroral pulsation a TAD is generated that propagates equatorward away from the high-latitude auroral oval, depositing energy and transporting mass and momentum into the mid- and low-latitude thermosphere system. Depending on the amount of energy input into the high-latitude auroral zone, the TAD may travel to mid-latitudes, low-latitudes, or if sufficient energy is deposited, the TAD may even propagate across the opposite pole. These and other aspects of TAD generation will be shown. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.4943K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.4943K">Simultaneous observations of traveling convection vortices: Ionosphere-thermosphere coupling</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kim, Hyomin; Lessard, Marc R.; Jones, Sarah L.; Lynch, Kristina A.; Fernandes, Philip A.; Aruliah, Anasuya L.; Engebretson, Mark J.; Moen, Jøran I.; Oksavik, Kjellmar; Yahnin, Alexander G.; Yeoman, Timothy K. 2017-05-01 We present simultaneous observations of magnetosphere-ionosphere-thermosphere coupling over Svalbard during a traveling convection vortex (TCV) event. Various spaceborne and ground-based instruments made coordinated measurements, including magnetometers, particle detectors, an all-sky camera, European Incoherent Scatter (EISCAT) Svalbard Radar, Super Dual Auroral Radar Network (SuperDARN), and SCANning Doppler Imager (SCANDI). The instruments recorded TCVs associated with a sudden change in solar wind dynamic pressure. The data display typical features of TCVs including vortical ionospheric convection patterns seen by the ground magnetometers and SuperDARN radars and auroral precipitation near the cusp observed by the all-sky camera. Simultaneously, electron and ion temperature enhancements with corresponding density increase from soft precipitation are also observed by the EISCAT Svalbard Radar. The ground magnetometers also detected electromagnetic ion cyclotron waves at the approximate time of the TCV arrival. This implies that they were generated by a temperature anisotropy resulting from a compression on the dayside magnetosphere. SCANDI data show a divergence in thermospheric winds during the TCVs, presumably due to thermospheric heating associated with the current closure linked to a field-aligned current system generated by the TCVs. We conclude that solar wind pressure impulse-related transient phenomena can affect even the upper atmospheric dynamics via current systems established by a magnetosphere-ionosphere-thermosphere coupling process. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991PhDT.......245B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991PhDT.......245B">Polarizing Michelson Interferometer for Measuring Thermospheric Winds.</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bird, John C. The Polarizing Atmospheric Michelson Interferometer, PAMI, a new version of the Wide Angle Michelson Interferometer, is used to measure winds in the thermosphere. In the polarizing instrument, the optical path difference is changed simply by rotating a polarizing filter external to the interferometer. This allows a very simple scanning mechanism. PAMI's general behavior has been modeled in terms of Mueller matrices providing a framework for the analysis of partial polarization states within the Michelson Interferometer (MI). A field instrument based on the above concept was designed and built. PAMI is similar to other instruments such as WAMDII (Shepherd et al., 1985) that measure thermospheric winds and temperatures, retaining the benefits of high light throughput, while offering advantages including lower cost, simplicity, and portability. PAMI was constructed from readily available components wherever possible to facilitate replacement. The instrument is highly sensitive and thus is designed to be used for field measurements at locations far from city lights. Results are shown from the AIDA observation campaign in Puerto Rico (17^circ57 ^'0^{ ''}N, 66^ circ52^'42 ^{''}W) where coordinated observations were made by PAMI along with other optical and radio measurements during April and May 1989. Intensities of the green line layer at 95 km were compared to those observed by several other instruments. For example, MORTI (Mesopause Oxygen Rotational Temperature Imager), a co-located instrument which was looking at the 94 km 867.6 nm molecular oxygen emission. MORTI and PAMI emission rates were found to show the same trends. PAMI intensities were also compared to two green-line photometers. In these comparisons the trends in observed emission rates were the same for all three instruments. On the brightest night recorded during April, the zenith emission rate reached over 400 Rayleighs; emission enhancements were sometimes related to auroral events. During the observing period of April 4 to April 11, 1989, most of the observations of the 95 km airglow were after midnight where the winds were found to be generally towards the north east at about 50 to 100 m/s. During auroral activity this wind vector always turned counterclockwise, towards the west. During the nights of May 2 and May 6 these wind vectors follow a wave-like variation in magnitude and direction. It is concluded that auroral activity changes the global circulation in a way that sometimes transports increased amounts of oxygen atoms over Arecibo. Wind comparisons were made with a Fabry-Perot interferometer operating at the same time at the Arecibo observatory, 60 km away. The agreement was generally good, with some differences in detail, in some cases, for the eastward wind component. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616252L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616252L">APIS : an interactive database of HST-UV observations of the outer planets</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lamy, Laurent; Henry, Florence; Prangé, Renée; Le Sidaner, Pierre 2014-05-01 Remote UV measurement of the outer planets offer a wealth of informations on rings, moons, planetary atmospheres and magnetospheres. Auroral emissions in particular provide highly valuable constraints on the auroral processes at work and the underlying coupling between the solar wind, the magnetosphere, the ionosphere and the moons. Key observables provided by high resolution spectro-imaging include the spatial topology and the dynamics of active magnetic field lines, the radiated and the precipitated powers or the energy of precipitating particles. The Hubble Space Telescope (HST) acquired thousands of Far-UV spectra and images of the aurorae of Jupiter, Saturn and Uranus since 1993, feeding in numerous magnetospheric studies. But their use remains generally limited, owing to the difficulty to access and use raw and value-added data. APIS, the egyptian god of fertilization, is also the acronym of a new database (Auroral Planetary Imaging and Spectroscopy), aimed at facilitating the use of HST planetary auroral observations. APIS is based at the Virtual Observatory (VO) of Paris and provides a free and interactive access to a variety of high level data through a simple research interface and standard VO tools (as Aladin, Specview). We will present the capabilities of APIS and illustrate them with several examples. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EPSC....8..573L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EPSC....8..573L">APIS : an interactive database of HST-UV observations of the outer planets</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lamy, L.; Henry, F.; Prangé, R.; Le Sidaner, P. 2013-09-01 Remote UV measurement of the outer planets are a wealth of informations on rings, moons, planetary atmospheres and magnetospheres. Auroral emissions in particular provide highly valuable constraints on the auroral processes at work and the underlying coupling between the solar wind, the magnetosphere, the ionosphere and the moons. Key observables provided by high resolution spectro-imaging include the spatial topology and the dynamics of active magnetic field lines, the radiated and the precipitated powers or the energy of precipitating particles. The Hubble Space Telescope (HST) acquired thousands of Far-UV spectra and images of the aurorae of Jupiter, Saturn and Uranus since 1993, feeding in numerous magnetospheric studies. But their use remains generally limited, owing to the difficulty to access and use raw and value-added data. APIS, the egyptian god of fertilization, is also the acronym of a new database (Auroral Planetary Imaging and Spectroscopy, Figure 1), aimed at facilitating the use of HST planetary auroral observations. APIS is based at the Virtual Observatory (VO) of Paris and provides a free and interactive access to a variety of high level data through a simple research interface and standard VO tools. We will present the capabilities of APIS and illustrate them with several examples. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...10628897V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...10628897V">Polar UVI observations of dayside auroral transient events</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vorobjev, V. G.; Yagodkina, O. I.; Sibeck, D. G.; Liou, K.; Meng, C.-I. 2001-12-01 We analyze Polar Ultraviolet Imager (UVI) observations of auroral transient events (ATEs) in the dayside Northern Hemisphere. During 5 winter months in 1996 and 1997, we found 31 prenoon ATEs but only 13 afternoon events. Prenoon and afternoon event characteristics differ. Prenoon ATEs generally appear as bright spots of auroral luminosity in the area from 0800 to 1000 magnetic local time (MLT) and 74.5° and 76.5° corrected geomagnetic latitude (CGL). Bright aurorae then quickly expand westward and poleward, accompanied by high-latitude magnetic impulsive events (MIE) and traveling convection vortices (TCV). Afternoon ATEs usually appear as a sudden intensification of aurorae in the area from 1400 to 1600 MLT and 75.5° to 78.5° CGL. Within 15-20 min the bright band of luminosity extends eastward to reach 2000-2100 MLT at 70°-72° CGL. Although midlatitude and low-latitude ground magnetograms in the evening sector record increases in the horizontal component of the magnetic field, no corresponding features occur at stations in the morning sector. Afternoon ATEs correspond to abrupt changes in the interplanetary magnetic field (IMF) orientation, but not to significant variations of the solar wind dynamic pressure, indicating that the auroral transient events occur as part of the magnetospheric response to abrupt changes in the foreshock geometry. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110023419&hterms=geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeomagnetic%2Breversal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110023419&hterms=geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeomagnetic%2Breversal">Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Emery, Barbara A.; Richardson, Ian G.; Evans, David S.; Rich, Frederick J.; Wilson, Gordon R. 2011-01-01 The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from S to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005 -2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (approx.1980, approx.1990, and approx. 2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995-1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27 -day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the > 2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods, showing that processes in the magnetosphere act as a low-pass filter between the solar wind and the radiation belt. The A(sub p)/K(sub p) magnetic currents observed at subauroral latitudes are sensitive to proton auroral precipitation, especially for 9-day and shorter periods, while the A(sub p)/K(sub p) currents are governed by electron auroral precipitation for 13.5- and 27-day periodicities. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active">9</li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active">10</li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040121135','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040121135">Simultaneous Chandra X-ray, HST Ultraviolet, and Ulysses Radio Observations of Jupiter's Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Elsner, R. F.; Lugaz, N.; Waite, J. H., Jr.; Cravens, T. E.; Gladstone, G. R.; Ford, P.; Grodent, D.; Bhardwaj, A.; MacDowall, R. J. 2004-01-01 Observations of Jupiter carried out by the Chandra ACIS-S instrument over 24-26 February, 2003, show that the auroral X-ray spectrum consists of line emission consistent with high-charge states of precipitating ions, and not a continuum as might be expected from bremsstrahlung. The part of the spectrum due to oxygen peaks around 650 eV, which indicates a high fraction of fully-stripped oxygen in the precipitating ion flux. A combination of the OVIII emission lines at 653 eV and 774 eV, as well as the OVII emission lines at 561 eV and 666 eV, are evident in the measure auroral spectrum. There is also line emission at lower energies in the spectral region extending from 250 to 350 eV, which could be from sulfur and/or carbon. The Jovian auroral X- ray spectra are significantly different from the X-ray spectra of comets. The charge state distribution of the oxygen ions implied by the measured auroral X-ray spectra strongly suggests that, independent of the source of the energetic ions - magnetospheric or solar wind - the ions have undergone additional acceleration. This spectral evidence for ion acceleration is also consistent with the relatively high intensities of the X-rays compared to the available phase space density of the (unaccelerated) source populations of solar wind or magnetospheric ions at Jupiter, which are orders of magnitude too small to explain the observed emissions. The Chandra X-ray observations were executed simultaneously with observations at ultraviolet wavelengths by the Hubble Space Telescope and at radio wavelengths by the Ulysses spacecraft. These additional data sets suggest that the source of the X-rays is magnetospheric in origin, and that the precipitating particles are accelerated by strong field-aligned electric fields, which simultaneously create both the several-MeV energetic ion population and the relativistic electrons observed in situ by Ulysses that are correlated with approximately 40 minute quasi-periodic radio outbursts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750022625','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750022625">Kinetic description of ionospheric dynamics in the three-fluid approximation</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Comfort, R. H. 1975-01-01 Conservation equations are developed in the three-fluid approximation for general application problems of ionospheric dynamics in the altitude region 90 km to 800 km for all geographic locations. These equations are applied to a detailed study of auroral E region neutral winds and their relationship to ionospheric plasma motions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000AnGeo..18..945R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000AnGeo..18..945R">Annual and semiannual variations in the ionospheric F2-layer: II. Physical discussion</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Rishbeth, H.; Müller-Wodarg, I. C. F.; Zou, L.; Fuller-Rowell, T. J.; Millward, G. H.; Moffett, R. J.; Idenden, D. W.; Aylward, A. D. 2000-08-01 The companion paper by Zou et al. shows that the annual and semiannual variations in the peak F2-layer electron density (NmF2) at midlatitudes can be reproduced by a coupled thermosphere-ionosphere computational model (CTIP), without recourse to external influences such as the solar wind, or waves and tides originating in the lower atmosphere. The present work discusses the physics in greater detail. It shows that noon NmF2 is closely related to the ambient atomic/molecular concentration ratio, and suggests that the variations of NmF2 with geographic and magnetic longitude are largely due to the geometry of the auroral ovals. It also concludes that electric fields play no important part in the dynamics of the midlatitude thermosphere. Our modelling leads to the following picture of the global three-dimensional thermospheric circulation which, as envisaged by Duncan, is the key to explaining the F2-layer variations. At solstice, the almost continuous solar input at high summer latitudes drives a prevailing summer-to-winter wind, with upwelling at low latitudes and throughout most of the summer hemisphere, and a zone of downwelling in the winter hemisphere, just equatorward of the auroral oval. These motions affect thermospheric composition more than do the alternating day/night (up-and-down) motions at equinox. As a result, the thermosphere as a whole is more molecular at solstice than at equinox. Taken in conjunction with the well-known relation of F2-layer electron density to the atomic/molecular ratio in the neutral air, this explains the F2-layer semiannual effect in NmF2 that prevails at low and middle latitudes. At higher midlatitudes, the seasonal behaviour depends on the geographic latitude of the winter downwelling zone, though the effect of the composition changes is modified by the large solar zenith angle at midwinter. The zenith angle effect is especially important in longitudes far from the magnetic poles. Here, the downwelling occurs at high geographic latitudes, where the zenith angle effect becomes overwhelming and causes a midwinter depression of electron density, despite the enhanced atomic/molecular ratio. This leads to a semiannual variation of NmF2. A different situation exists in winter at longitudes near the magnetic poles, where the downwelling occurs at relatively low geographic latitudes so that solar radiation is strong enough to produce large values of NmF2. This circulation-driven mechanism provides a reasonably complete explanation of the observed pattern of F2 layer annual and semiannual quiet-day variations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040110876&hterms=ionosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dionosphere','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040110876&hterms=ionosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dionosphere">Magnetosphere-Ionosphere Coupling in the Auroral Zone</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Schriver, David 2004-01-01 The visual light display at high latitudes referred to as the aurora fascinates casual observers and researchers alike. The natural question is what causes the aurora? We know that energized electrons streaming along the Earth's ambient magnetic field and colliding with atmospheric particles produce aurora. We do not know for certain, however, how these electrons are accelerated to high energies primarily in the field-aligned direction toward the Earth, or what the drivers of this acceleration are. As such, the goal of this Guest Investigator research project was to examine the physical processes that can cause field-aligned acceleration of plasma particles in the auroral region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810019183','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810019183">Sounding rocket research Aries/Firewheel, series 22, issue 15</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Mozer, F. S. 1981-01-01 Rocket experiments in ionospheric particle and field research flow in seven programs during the last decade are summarized. Experimental techniques were developed and are discussed including the double-probe field technique. The auroral zone, polar cap, and equatorial spread F were studied. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA14093.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA14093.html">Lengthy Coronal Hole</a> <a target="_blank" rel="noopener noreferrer" href="https://images.nasa.gov/">NASA Image and Video Library</a> 2017-01-09 An elongated coronal hole rotated across the face of the sun this past week so that it is now streaming solar wind towards Earth (Jan. 2-5, 2017). Coronal holes are areas of open magnetic field from which solar wind particles stream into space. In this wavelength of extreme ultraviolet light it appears as a dark area near the center and lower portion of the sun. The particle stream will likely generate aurora here on Earth. Check spaceweather.com for updates on auroral activity. Movies are available at http://photojournal.jpl.nasa.gov/catalog/PIA14093 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20100002035&hterms=time+zone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtime%2Bzone','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20100002035&hterms=time+zone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtime%2Bzone">Hemispheric Asymmetries in Substorm Recovery Time Scales</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Fillingim, M. O.; Chua, D H.; Germany, G. A.; Spann, James F. 2009-01-01 Previous statistical observations have shown that the recovery time scales of substorms occurring in the winter and near equinox (when the nighttime auroral zone was in darkness) are roughly twice as long as the recovery time scales for substorms occurring in the summer (when the nighttime auroral region was sunlit). This suggests that auroral substorms in the northern and southern hemispheres develop asymmetrically during solstice conditions with substorms lasting longer in the winter (dark) hemisphere than in the summer (sunlit) hemisphere. Additionally, this implies that more energy is deposited by electron precipitation in the winter hemisphere than in the summer one during substorms. This result, coupled with previous observations that have shown that auroral activity is more common when the ionosphere is in darkness and is suppressed when the ionosphere is in daylight, strongly suggests that the ionospheric conductivity plays an important role governing how magnetospheric energy is transferred to the ionosphere during substorms. Therefore, the ionosphere itself may dictate how much energy it will accept from the magnetosphere during substorms rather than this being an externally imposed quantity. Here, we extend our earlier work by statistically analyzing the recovery time scales for a large number of substorms observed in the conjugate hemispheres simultaneously by two orbiting global auroral imagers: Polar UVI and IMAGE FUV. Our current results are consistent with previous observations. The recovery time scales are observed to be longer in the winter (dark) hemisphere while the auroral activity has a shorter duration in the summer (sunlit) hemisphere. This leads to an asymmetric energy input from the magnetosphere to the ionosphere with more energy being deposited in the winter hemisphere than in the summer hemisphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMSM51A0280H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMSM51A0280H">Temporal Development of Auroral Acceleration Potentials: High-Altitude Evolutionary Sequences, Drivers and Consequences</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hull, A. J.; Wilber, M.; Chaston, C.; Bonnell, J.; Mozer, F.; McFadden, J.; Goldstein, M.; Fillingim, M. 2007-12-01 The region above the auroral acceleration region is an integral part of the auroral zone electrodynamic system. At these altitudes (≥ 3 Re) we find the source plasma and fields that determine acceleration processes occurring at lower altitudes, which play a key role in the transport of mass and energy into the ionosphere. Dynamic changes in these high-altitude regions can affect and/or control lower-altitude acceleration processes according to how field-aligned currents and specific plasma sources form and decay and how they are spatially distributed, and through magnetic configuration changes deeper in the magnetotail. Though much progress has been made, the time development and consequential effects of the high-altitude plasma and fields are still not fully understood. We present Cluster multi-point observations at key instances within and above the acceleration region (> 3 RE) of evolving auroral arc current systems. Results are presented from events occurring under different conditions, such as magnetospheric activity, associations with density depletions or gradients, and Alfvenic turbulence. A preliminary survey, primarily at or near the plasma sheet boundary, indicates quasi- static up-down current pair systems are at times associated with density depletions and other instances occur in association with density gradients. The data suggest that such quasi-static current systems may be evolving from structured Alfvenic current systems. We will discuss the temporal development of auroral acceleration potentials, plasma and currents, including quasi-static system formation from turbulent systems of structured Alfvenic field-aligned currents, density depletion and constituent reorganization of the source and ionospheric plasma that transpire in such systems. Of particular emphasis is how temporal changes in magnetospheric source plasma and fields affect the development of auroral acceleration potentials at lower altitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990092494&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990092494&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2Benergy">Comparison of Dawn and Dusk Precipitating Electron Energy Populations Shortly After the Initial Shock for the January 10th, 1997 Magnetic Cloud</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spann, J.; Germany, G.; Swift, W.; Parks, G.; Brittnacher, M.; Elsen, R. 1997-01-01 The observed precipitating electron energy between 0130 UT and 0400 UT of January 10 th, 1997, indicates that there is a more energetic precipitating electron population that appears in the auroral oval at 1800-2200 UT at 030) UT. This increase in energy occurs after the initial shock of the magnetic cloud reaches the Earth (0114 UT) and after faint but dynamic polar cap precipitation has been cleared out. The more energetic population is observed to remain rather constant in MLT through the onset of auroral activity (0330 UT) and to the end of the Polar spacecraft apogee pass. Data from the Ultraviolet Imager LBH long and LBH short images are used to quantify the average energy of the precipitating auroral electrons. The Wind spacecraft located about 100 RE upstream monitored the IMF and plasma parameters during the passing of the cloud. The affects of oblique angle viewing are included in the analysis. Suggestions as to the source of this hot electron population will be presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996AnGeo..14..589K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996AnGeo..14..589K">The convection electrojet and the substorm electrojet</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kamide, Y.; Nakamura, R. 1996-06-01 Enhancements in the auroral electrojets associated with magnetospheric substorms result from those in either the electric field or the ionospheric conductivities, or both. Their relative importance varies significantly, even during a single substorm, depending on the location as well as on the substorm phases. It is predicted that different parts of the electrojets tend to respond in different ways to substorm activity. The unprecedented, unique opportunity for CLUSTER spacecraft observations of electric/magnetic fields and precipitating particles, combined with radar measurements of ionospheric quantities and with ground magnetometers, will provide us with crucial information regarding the physical nature of the separation between the electric field-dominant'' and conductivity-dominant'' auroral electrojets. This study also discusses the implications of these two auroral-electrojet components in terms of solar wind-magnetosphere-ionosphere interactions. Acknowledgements. This study is supported in part by the Ministry of Education, Science, Sports, and Culture in Japan, under a Grant-in-Aid for Scientific Research (Category B). Topical Editor D. Alcaydé thanks M. Lockwood and N. J. Fox for their help in evaluating this paper.--> Correspondence to: Y. Kamide--> </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AnGeo..27.1321M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AnGeo..27.1321M">Pre-storm NmF2 enhancements at middle latitudes: delusion or reality?</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mikhailov, A. V.; Perrone, L. 2009-03-01 A critical analysis of recent publications devoted to the NmF2 pre-storm enhancements is performed. There are no convincing arguments that the observed cases of NmF2 enhancements at middle and sub-auroral latitudes bear a relation to the following magnetic storms. In all cases considered the NmF2 pre-storm enhancements were due to previous geomagnetic storms, moderate auroral activity or they presented the class of positive quiet time events (Q-disturbances). Therefore, it is possible to conclude that there is no such an effect as the pre-storm NmF2 enhancement as a phenomenon inalienably related to the following magnetic storm. The observed nighttime NmF2 enhancements at sub-auroral latitudes may result from plasma transfer from the plasma ring area by meridional thermospheric wind. Enhanced plasmaspheric fluxes into the nighttime F2-region resulted from westward substorm-associated electric fields is another possible source of nighttime NmF2 enhancements. Daytime positive Q-disturbances occurring under very low geomagnetic activity level may be related to the dayside cusp activity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SunGe..11..105D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SunGe..11..105D">Comparison of substorms near two solar cycle maxima: (1999-2000 and 2012-2013)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Despirak, I.; Lubchich, A.; Kleimenova, N. 2016-05-01 We present the comparative analysis of the substorm behavior during two solar cycle maxima. The substorms, observed during the large solar cycle maximum (1999- 2000, with Wp> 100) and during the last maximum (2012-2013 with Wp~60), were studied. The considered substorms were divided into 3 types according to auroral oval dynamic. First type - substorms which are observed only at auroral latitudes ("usual" substorms); second type - substorms which propagate from auroral latitudes (<70?) to polar geomagnetic latitudes (>70°) ("expanded" substorms, according to expanded oval); third type - substorms which are observed only at latitudes above ~70° in the absence of simultaneous geomagnetic disturbances below 70° ("polar" substorms, according to contracted oval). Over 1700 substorm events have been analyzed. The following substorm characteristics have been studied: (i) the seasonal variations, (ii) the latitudinal range of the occurrence, (iii) solar wind and IMF parameters before substorm onset, (iiii) PC-index before substorm onset. Thus, the difference between two solar activity maxima could be seen in the difference of substorm behavior in these periods as well. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740015261','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740015261">Role of sudden commencements in triggering magnetospheric substorms. M.S. Thesis; [based on ATS 1 data</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Newell, R. E. 1974-01-01 Sudden commencement events are examined in terms of available auroral-zone and low-latitude magnetic field, data, interplanetary plasma and magnetic field data, and magnetospheric electron flux and magnetic field data from the geostationary satellite ATS 1. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981GeoRL...8..607B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981GeoRL...8..607B">An S3-3 search for confined regions of large parallel electric fields</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Boehm, M. H.; Mozer, F. S. 1981-06-01 S3-3 satellite passes through several hundred perpendicular shocks are searched for evidence of large, mostly parallel electric fields (several hundred millivolts per meter, total potential of several kilo-volts) in the auroral zone magnetosphere at altitudes of several thousand kilometers. The actual search criteria are that one or more E-field data points have a parallel component E sub z greater than 350 mV/m in general, or 100 mV/m for data within 10 seconds of a perpendicular shock, since double layers might be likely, in such regions. Only a few marginally convincing examples of the electric fields are found, none of which fits a double layer model well. From statistics done with the most unbiased part of the data set, upper limits are obtained on the number and size of double layers occurring in the auroral zone magnetosphere, and it is concluded that the double layers most probably cannot be responsible for the production of diffuse aurora or inverted-V events. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1438123-simultaneous-observations-traveling-convection-vortices-ionosphere-thermosphere-coupling-coupling-tcv','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1438123-simultaneous-observations-traveling-convection-vortices-ionosphere-thermosphere-coupling-coupling-tcv">Simultaneous observations of traveling convection vortices: Ionosphere-thermosphere coupling: M-I-T COUPLING OF TCV</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/pages">DOE PAGES</a> Kim, Hyomin; Lessard, Marc R.; Jones, Sarah L.; ... 2017-03-11 We present simultaneous observations of magnetosphere-ionosphere-thermosphere coupling over Svalbard during a traveling convection vortex (TCV) event. Various spaceborne and ground-based instruments made coordinated measurements, including magnetometers, particle detectors, an all-sky camera, European Incoherent Scatter (EISCAT) Svalbard Radar, Super Dual Auroral Radar Network (SuperDARN), and SCANning Doppler Imager (SCANDI). The instruments recorded TCVs associated with a sudden change in solar wind dynamic pressure. The data display typical features of TCVs including vortical ionospheric convection patterns seen by the ground magnetometers and SuperDARN radars and auroral precipitation near the cusp observed by the all-sky camera. Simultaneously, electron and ion temperature enhancements withmore » corresponding density increase from soft precipitation are also observed by the EISCAT Svalbard Radar. The ground magnetometers also detected electromagnetic ion cyclotron waves at the approximate time of the TCV arrival. This implies that they were generated by a temperature anisotropy resulting from a compression on the dayside magnetosphere. SCANDI data show a divergence in thermospheric winds during the TCVs, presumably due to thermospheric heating associated with the current closure linked to a field-aligned current system generated by the TCVs. We conclude that solar wind pressure impulse-related transient phenomena can affect even the upper atmospheric dynamics via current systems established by a magnetosphere-ionosphere-thermosphere coupling process.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1438123','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1438123">Simultaneous observations of traveling convection vortices: Ionosphere-thermosphere coupling: M-I-T COUPLING OF TCV</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Kim, Hyomin; Lessard, Marc R.; Jones, Sarah L. We present simultaneous observations of magnetosphere-ionosphere-thermosphere coupling over Svalbard during a traveling convection vortex (TCV) event. Various spaceborne and ground-based instruments made coordinated measurements, including magnetometers, particle detectors, an all-sky camera, European Incoherent Scatter (EISCAT) Svalbard Radar, Super Dual Auroral Radar Network (SuperDARN), and SCANning Doppler Imager (SCANDI). The instruments recorded TCVs associated with a sudden change in solar wind dynamic pressure. The data display typical features of TCVs including vortical ionospheric convection patterns seen by the ground magnetometers and SuperDARN radars and auroral precipitation near the cusp observed by the all-sky camera. Simultaneously, electron and ion temperature enhancements withmore » corresponding density increase from soft precipitation are also observed by the EISCAT Svalbard Radar. The ground magnetometers also detected electromagnetic ion cyclotron waves at the approximate time of the TCV arrival. This implies that they were generated by a temperature anisotropy resulting from a compression on the dayside magnetosphere. SCANDI data show a divergence in thermospheric winds during the TCVs, presumably due to thermospheric heating associated with the current closure linked to a field-aligned current system generated by the TCVs. We conclude that solar wind pressure impulse-related transient phenomena can affect even the upper atmospheric dynamics via current systems established by a magnetosphere-ionosphere-thermosphere coupling process.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950045584&hterms=MOOS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMOOS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950045584&hterms=MOOS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMOOS">Correlated variations of UV and radio emissions during an outstanding Jovian auroral event</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Prange, R.; Zarka, P.; Ballester, G. E.; Livengood, T. A.; Denis, L.; Carr, T.; Reyes, F.; Bame, S. J.; Moos, H. W. 1993-01-01 An exceptional Jovian aurora was detected in the FUV on December 21, 1990, by means of Vilspa and Goddard Space Flight Center (GFSC) International Ultraviolet Explorer (IUE) observations. This event included intensification by a factor of three between December 20 and 21, leading to the brightest aurora identified in the IUE data analyzed, and, in the north, to a shift of the emission peak towards larger longitudes. The Jovian radio emission simultaneously recorded at decameter wavelengths in Nancay also exhibits significant changes, from a weak and short-duration emission on December 20 to a very intense one, lasting several hours, on December 21. Confirmation of this intense radio event is also found in the observations at the University of Florida on December 21. The emissions are identified as right-handed Io-independent 'A' (or 'non Io-A') components from the northern hemisphere. The radio source region deduced from the Nancay observations lies, for both days, close to the UV peak emission, exhibiting in particular a similar shift of the source region toward larger longitudes from one day to the next. A significant broadening of the radio source was also observed and it is shown that on both days, the extent of the radio source closely followed the longitude range for which the UV brightness exceeds a given threshold. The correlated variations, both in intensity and longitude, strongly suggest that a common cause triggered the variation of the UV and radio emissions during this exceptional event. On one hand, the variation of the UV aurora could possibly be interpreted according to the Prange and Elkhamsi (1991) model of diffuse multicomponent auroral precipitation (electron and ion): it would arise from an increase in the precipitation rate of ions together with an inward shift of their precipitation locus from L approximately equal 10 to L approximately equal 6. On the other hand, the analysis of Ulysses observations in the upstream solar wind suggests that a significant disturbance in the solar wind, involving the generation of an interplanetary shock and the presence of a CME have interacted with the Jovian magnetosphere at about the time of the auroral event. Both arguments suggest that we may have observed for the first time a magnetic storm-type interaction in an outer planet magnetosphere, affecting simultaneously several auroral processes. Conversely, the observed relationship between the level of UV auroral activity and the detection of decameter emission (DAM), if it were a typical feature, might argue in favour of a more direct and permanent association between the auroral processes leading to UV and radio aurorae, possibly related to 'discrete-arc'-like activity and electron precipitation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950045383&hterms=Geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DGeomagnetic%2Breversal','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950045383&hterms=Geomagnetic+reversal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DGeomagnetic%2Breversal">Auroral activity associated with Kelvin-Helmholtz instability at the inner edge of the low-latitude boundary layer</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Farrugia, C. J.; Sandholt, P. E.; Burlaga, L. F. 1994-01-01 Auroral activity occurred in the late afternoon sector (approx. 16 MLT) in the northern hemisphere during the passage at Earth of an interplanetary magnetic cloud on January 14, 1988. The auroral activity consisted of a very dynamic display which was preceded and followed by quiet auroral displays. During the quiet displays, discrete rayed arcs aligned along the geomagnetic L shells were observed. In the active stage, rapidly evolving spiral forms centered on magnetic zenith were evident. The activity persisted for many minutes and was characterized by the absence of directed motion. They were strongly suggestive of intense filaments of upward field-aligned currents embedded in the large-scale region 1 current system. Distortions of the flux ropes as they connect from the equatorial magnetosphere to the ionosphere were witnessed. We assess as possible generating mechanisms three nonlocal sources known to be associated with field-aligned currents. Of these, partial compressions of the magnetosphere due to variations of solar wind dynamic pressure seem an unlikely source. The possibility that the auroral forms are due to reconnection is investigated but is excluded because the active aurora were observed on the closed field line region just equatorward of the convection reversal boundary. To support this conclusion further, we apply recent results on the mapping of ionospheric regions to the equatorial plane based on the Tsyganenko 1989 model (Kaufmann et al., 1993). We find that for comparable magnetic activity the aurora map to the equatorial plane at X(sub GSM) = approx. 3 R(sub E) and approx. 2 R(sub E) inward of the magnetopause, that is, the inner edge of the boundary layer close to dusk. Since the auroral forms are manifestly associated with magnetic field shear, a vortical motion at the equatorial end of the flux rope is indicated, making the Kelvin-Helmholtz instability acting at the inner edge of the low-latitude boundary layer the most probable generating source. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870057861&hterms=connected+objects&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dconnected%2Bobjects','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870057861&hterms=connected+objects&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dconnected%2Bobjects">Conditions for double layers in the earth's magnetosphere and perhaps in other astrophysical objects</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lyons, L. R. 1987-01-01 It is suggested that the features which govern the formation of the double layers are: (1) the divergence of the magnetospheric electric field, (2) the ionospheric conductivity, and (3) the current-voltage characteristics of auroral magnetic field lines. Also considered are conditions in other astrophysical objects that could lead to the formation of DLs in a manner analogous to what occurs in the earth's auroral zones. It is noted that two processes can drive divergent Pedersen currents within a collisional conducting layer: (1) sheared plasma flow applied anywhere along the magnetic field lines connected to the conducting layer and (2) a neutral flow with shear within the conducting layer. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM33C2518C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM33C2518C">Solar Cycle and Geomagnetic Activity Variation of Topside Ionospheric Upflow as Measured by DMSP</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Coley, W. R.; Hairston, M. R. 2016-12-01 Under the proper conditions a considerable amount of plasma can escape the Earth's ionosphere into the magnetosphere. Indeed, there are indications that at least part of the time the ionosphere may be the dominant source of ions for the plasma sheet and near-Earth portion of the magnetosphere. The upward flux of thermal O+ from the lower part of the topside ionosphere actively provides plasma into intermediate altitudes where they may be given escape energy by various mechanisms. Previous work has indicated that there is considerable time variation of upwelling low energy ionospheric plasma to these intermediate altitudes during moderate to high solar activity. Here we use the SSIES thermal plasma instruments on board the Defense Meteorological Satellite Program (DMSP) F13-F19 series of spacecraft to examine the vertical flux of thermal O+ from the deep solar minimum of 2008-2009 to the moderately active period of 2012-2015. Separately integrating the upward and downward fluxes over the high-latitude region (auroral zone and polar cap) allows the observation of the total upflow/downflow as a function of the current geomagnetic conditions, solar cycle, and solar wind conditions. In particular we investigate the incidence of high upward flux events as a function of solar wind velocity and density during the deepest solar minimum since the space age began. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active">10</li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active">11</li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760043542&hterms=highly+charged+heavy+ions&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dhighly%2Bcharged%2Bheavy%2Bions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760043542&hterms=highly+charged+heavy+ions&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dhighly%2Bcharged%2Bheavy%2Bions">The charge spectrum of positive ions in a hydrogen aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lynch, J.; Pulliam, D.; Leach, R.; Scherb, F. 1976-01-01 An auroral ion charge spectrometer was flown into a hydrogen aurora on a Javelin sounding rocket launched from Churchill, Manitoba. The instrument contained an electrostatic analyzer which selected particles with incident energy per unit charge up to 20 keV/charge and an 80-kV power supply which accelerated these ions onto an array of solid state detectors. Ions tentatively identified as H(+), He(+2), and O(+) were detected from 225 to 820 km in altitude. The experiment did not discriminate between H(+) and He(+), or between O(+), N(+), and C(+). Upper limits of highly charged heavy ion abundances have been set at 20% of the He(+2) and 0.15% of the H(+). It is concluded that both terrestrial and solar wind sources play significant roles in auroral ion precipitation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985PolRe..38....1A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985PolRe..38....1A">The polar caps</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Akasofu, S.-I. 1985-12-01 According to the most common definition, the 'polar cap' is the region bounded by the average or statistical auroral oval. Studies of the effects of the interplanetary magnetic field (IMF) on various upper atmospheric phenomena are reviewed. The Antarctic region and the Arctic region represent an area for such investigations. Particular attention is given in this paper to those observations in the highest latitude region which provide some information concerning corresponding changes of the internal structure of the magnetosphere. A definition and working definition of the polar cap are considered along with the IMF and magnetospheric models, the entry of solar energetic electrons, statistical studies regarding the aurora, individual events, polar cap arcs, the cusp aurora, auroral electron precipitation, convection, ionospheric currents and field-aligned currents, the ionosphere, the thermosphere, polar rain, polar wind, and hopping motions of heavy ions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSA33B..07P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSA33B..07P">Interhemispheric Propagation and Interactions of Auroral LSTIDs near the Equator</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pradipta, R.; Valladares, C.; Carter, B. A.; Doherty, P. 2016-12-01 In this work, we used experimental observations based on GPS total electron content (TEC) and ionosonde measurements to study some of the physics behind large-scale traveling ionospheric disturbances (LSTIDs) during the 26 September 2011 geomagnetic storm. In particular, we looked at how these LSTIDs propagate from the auroral zones all the way to the equatorial region and examined how the auroral LSTIDs from opposite hemispheres interact/interfere near the geomagnetic equator. We found that these LSTIDs had an overall propagation speed of ˜700 m/s. Furthermore, the resultant amplitude of the LSTID interference pattern was found to far exceed the sum of individual amplitudes of the incoming LSTIDs. We suspect that this peculiar intensification of auroral LSTIDs around the geomagnetic equator is facilitated by the significantly higher ceiling/canopy of the ionospheric plasma layer there. Normally, acoustic-gravity waves (AGWs) that leak upward (and thus increase in amplitude) would find a negligible level of plasma density at the topside ionosphere. However, the tip of the equatorial fountain at the geomagnetic equator constitutes a significant amount of plasma at a topside-equivalent altitude. The combination of increased AGW amplitudes and a higher plasma density at such altitude would therefore result in higher-amplitude LSTIDs in this particular region, as demonstrated in our observations and analysis. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMSM51A1387M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMSM51A1387M">Dynamics of Auroras Conjugate to the Dayside Reconnection Region.</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mende, S. B.; Frey, H. U.; Doolittle, J. H. 2006-12-01 During periods of northward IMF Bz, observations of the IMAGE satellite FUV instrument demonstrated the existence of an auroral footprint of the dayside lobe reconnection region. Under these conditions the dayside "reconnection spot" is a distinct feature being separated from the dayside auroral oval. In the IMAGE data, ~100 km spatial and 2 minutes temporal resolution, this feature appeared as a modest size, 200 to 500 km in diameter, diffuse spot which was present steadily while the IMF conditions lasted and the solar wind particle pressure was large enough to create a detectable signature. Based on this evidence, dayside reconnection observed with this resolution appears to be a steady state process. There have been several attempts to identify and study the "reconnection foot print aurora" with higher resolution from the ground. South Pole Station and the network of the US Automatic Geophysical Observatories (AGO-s) in Antarctica have all sky imagers that monitor the latitude region of interest (70 to 85 degrees geomagnetic) near midday during the Antarctic winter. In this paper we present sequences of auroral images that were taken during different conditions of Bz and therefore they are high spatial resolution detailed views of the auroras associated with reconnection. During negative Bz, auroras appear to be dynamic with poleward moving auroral forms that are clearly observed by ground based imagers with a ~few km spatial resolution. During positive Bz however the extremely high latitude aurora is much more stable and shows no preferential meridional motions. It should be noted that winter solstice conditions, needed for ground based observations, produce a dipole tilt in which reconnection is not expected to be symmetric and the auroral signatures might favor the opposite hemisphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AnGeo..27.1679M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AnGeo..27.1679M">Ionospheric storms at geophysically-equivalent sites - Part 1: Storm-time patterns for sub-auroral ionospheres</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mendillo, M.; Narvaez, C. 2009-04-01 The systematic study of ionospheric storms has been conducted primarily with groundbased data from the Northern Hemisphere. Significant progress has been made in defining typical morphology patterns at all latitudes; mechanisms have been identified and tested via modeling. At higher mid-latitudes (sites that are typically sub-auroral during non-storm conditions), the processes that change significantly during storms can be of comparable magnitudes, but with different time constants. These include ionospheric plasma dynamics from the penetration of magnetospheric electric fields, enhancements to thermospheric winds due to auroral and Joule heating inputs, disturbance dynamo electrodynamics driven by such winds, and thermospheric composition changes due to the changed circulation patterns. The ~12° tilt of the geomagnetic field axis causes significant longitude effects in all of these processes in the Northern Hemisphere. A complementary series of longitude effects would be expected to occur in the Southern Hemisphere. In this paper we begin a series of studies to investigate the longitudinal-hemispheric similarities and differences in the response of the ionosphere's peak electron density to geomagnetic storms. The ionosonde stations at Wallops Island (VA) and Hobart (Tasmania) have comparable geographic and geomagnetic latitudes for sub-auroral locations, are situated at longitudes close to that of the dipole tilt, and thus serve as our candidate station-pair choice for studies of ionospheric storms at geophysically-comparable locations. They have an excellent record of observations of the ionospheric penetration frequency (foF2) spanning several solar cycles, and thus are suitable for long-term studies. During solar cycle #20 (1964-1976), 206 geomagnetic storms occurred that had Ap≥30 or Kp≥5 for at least one day of the storm. Our analysis of average storm-time perturbations (percent deviations from the monthly means) showed a remarkable agreement at both sites under a variety of conditions. Yet, small differences do appear, and in systematic ways. We attempt to relate these to stresses imposed over a few days of a storm that mimic longer term morphology patterns occurring over seasonal and solar cycle time spans. Storm effects versus season point to possible mechanisms having hemispheric differences (as opposed to simply seasonal differences) in how solar wind energy is transmitted through the magnetosphere into the thermosphere-ionosphere system. Storm effects versus the strength of a geomagnetic storm may, similarly, be related to patterns seen during years of maximum versus minimum solar activity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title24-vol5/pdf/CFR-2014-title24-vol5-sec3285-405.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title24-vol5/pdf/CFR-2014-title24-vol5-sec3285-405.pdf">24 CFR 3285.405 - Severe wind zones.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a> 2014-04-01 ... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Severe wind zones. 3285.405 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Anchorage Against Wind § 3285.405 Severe wind zones. When any part of a home is installed within 1,500 feet of a coastline in Wind Zones II or III, the... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3285-405.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3285-405.pdf">24 CFR 3285.405 - Severe wind zones.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a> 2013-04-01 ... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Severe wind zones. 3285.405 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Anchorage Against Wind § 3285.405 Severe wind zones. When any part of a home is installed within 1,500 feet of a coastline in Wind Zones II or III, the... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3285-405.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3285-405.pdf">24 CFR 3285.405 - Severe wind zones.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a> 2012-04-01 ... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Severe wind zones. 3285.405 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Anchorage Against Wind § 3285.405 Severe wind zones. When any part of a home is installed within 1,500 feet of a coastline in Wind Zones II or III, the... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title24-vol5/pdf/CFR-2011-title24-vol5-sec3285-405.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title24-vol5/pdf/CFR-2011-title24-vol5-sec3285-405.pdf">24 CFR 3285.405 - Severe wind zones.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a> 2011-04-01 ... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Severe wind zones. 3285.405 Section... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Anchorage Against Wind § 3285.405 Severe wind zones. When any part of a home is installed within 1,500 feet of a coastline in Wind Zones II or III, the... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGP31C1315M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGP31C1315M">The Mesospheric Sodium Layer as a Remotely, Optically Pumped Magnetometer for Investigation of Birkeland Currents</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Matzka, J.; Johnsen, M. G.; Hoppe, U. P.; Serrano, A. 2016-12-01 By means of optical pumping, it is possible to use the naturally occurring sodium layer in the mesosphere to measure Earth's scalar magnetic field at 90 km above ground. This is an altitude not accessible by other means than rockets, which only will provide point measurements of very short time scales. We are planning to modify the sodium lidar at ALOMAR in Northern Norway to be able, for the first time, to measure and monitor the magnetic field in situ in the high latitude mesosphere over longer time scales. The planned modifications to the lidar instrument will allow alternating between the new magnetometer mode and its present mode for atmospheric temperatures and winds. The technique, which has been proposed earlier for measurements at low or mid-latitudes for studies of Earth's internal magnetic field, will in our project be applied to high latitudes in the auroral zone. This opens for a completely new domain of measurements of externally generated geomagnetic variations related to currents in the magnetosphere-ionosphere system. In particular, we aim to measure the magnetic field variations in close vicinity to Birkeland currents associated with particle precipitation events penetrating to altitudes below 90 km and small-scale, discrete auroral arcs. It is, furthermore, anticipated that it will be possible to detect horizontal current structures in the E-layer on much smaller length scales than it is presently possible from ground observations alone. During the project we plan take advantage of the rich space science infrastructure located in northern Norway, including ALOMAR, EISCAT and the Tromsø Geophysical Observatory magnetometer network. If possible, we also aim to make measurements in conjunction with overpasses of the SWARM satellites. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060051854&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DFord','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060051854&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DFord">Simultaneous Chandra X ray, Hubble Space Telescope Ultraviolet, and Ulysses Radio Observations of Jupiter's Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Elsner, R. F.; Lugaz, N.; Waite, J. H., Jr.; Cravens, T. E.; Gladstone, G. R.; Ford, P.; Grodent, D.; Bhardwaj. A.; MacDowall, R. J.; Desch, M. D. 8; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20060051854'); toggleEditAbsImage('author_20060051854_show'); toggleEditAbsImage('author_20060051854_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20060051854_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20060051854_hide"> 2005-01-01 Observations of Jupiter carried out by the Chandra Advanced CCD Imaging Spectrometer (ACIS-S) instrument over 24-26 February 2003 show that the auroral X-ray spectrum consists of line emission consistent with high-charge states of precipitating ions, and not a continuum as might be expected from bremsstrahlung. The part of the spectrum due to oxygen peaks around 650 eV, which indicates a high fraction of fully stripped oxygen in the precipitating ion flux. A combination of the OVIII emission lines at 653 eV and 774 eV, as well as the OVII emission lines at 561 eV and 666 eV, are evident in the measure auroral spectrum. There is also line emission at lower energies in the spectral region extending from 250 to 350 eV, which could be from sulfur and/or carbon. The Jovian auroral X-ray spectra are significantly different from the X-ray spectra of comets. The charge state distribution of the oxygen ions implied by the measured auroral X-ray spectra strongly suggests that independent of the source of the energetic ions, magnetospheric or solar wind, the ions have undergone additional acceleration. This spectral evidence for ion acceleration is also consistent with the relatively high intensities of the X rays compared with the available phase space density of the (unaccelerated) source populations of solar wind or magnetospheric ions at Jupiter, which are orders of magnitude too small to explain the observed emissions. The Chandra X-ray observations were executed simultaneously with observations at ultraviolet wavelengths by the Hubble Space Telescope and at radio wavelengths by the Ulysses spacecraft. These additional data sets suggest that the source of the X rays is magnetospheric in origin and that the precipitating particles are accelerated by strong field-aligned electric fields, which simultaneously create both the several-MeV energetic ion population and the relativistic electrons observed in situ by Ulysses that are correlated with approx.40 min quasi-periodic radio outbursts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMIN31B0074K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMIN31B0074K">Aurora Research: Earth/Space Data Fusion Powered by GIS and Python</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kalb, V. L.; Collado-Vega, Y. M.; MacDonald, E.; Kosar, B. 2017-12-01 The Aurora Borealis and Australis Borealis are visually spectacular, but are also an indicator of Sun-magnetosphere-ionosphere energy transfer during geomagnetic storms. The Saint Patrick's Day Storm of 2015 is a stellar example of this, and is the focus of our study that utilizes the Geographical Information Services of ArcGIS to bring together diverse and cross disciplinary data for analysis. This research leverages data from a polar-orbiting Earth science sensor band that is exquisitely sensitive to visible light, namely the Day/Night Band (DNB) of the VIIRS instrument onboard the Suomi NPP satellite. This Sun-synchronous data source can provide high temporal and spatial resolution observations of the aurorae, which is not possible with current space science instruments. This data can be compared with auroral model data, solar wind measurements, and citizen science data of aurora observations and tweets. While the proposed data sources are diverse in type and format, their common attribute is location. This is exploited by bringing all the data into ArcGIS for mapping and analysis. The Python programming language is used extensively to automate the data preprocessing, group the DNB and citizen science observations to temporal windows associated with an auroral model timestep, and print the data to a pdf mapbook for sharing with team members. There are several goals for this study: compare the auroral model predictions with DNB data, look for fine-grained structure of the aurora in the DNB data, compare citizen science data with DNB values, and correlate DNB intensity with solar wind data. This study demonstrates the benefits of using a GIS platform to bring together data that is diverse in type and format for scientific exploration, and shows how Python can be used to scale up to large datasets. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998AnGeo..16..441S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998AnGeo..16..441S">Substorm associated radar auroral surges: a statistical study and possible generation model</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shand, B. A.; Lester, M.; Yeoman, T. K. 1998-04-01 Substorm-associated radar auroral surges (SARAS) are a short lived (15-90 minutes) and spatially localised (~5° of latitude) perturbation of the plasma convection pattern observed within the auroral E-region. The understanding of such phenomena has important ramifications for the investigation of the larger scale plasma convection and ultimately the coupling of the solar wind, magnetosphere and ionosphere system. A statistical investigation is undertaken of SARAS, observed by the Sweden And Britain Radar Experiment (SABRE), in order to provide a more extensive examination of the local time occurrence and propagation characteristics of the events. The statistical analysis has determined a local time occurrence of observations between 1420 MLT and 2200 MLT with a maximum occurrence centred around 1700 MLT. The propagation velocity of the SARAS feature through the SABRE field of view was found to be predominately L-shell aligned with a velocity centred around 1750 m s-1 and within the range 500 m s-1 and 3500 m s-1. This comprehensive examination of the SARAS provides the opportunity to discuss, qualitatively, a possible generation mechanism for SARAS based on a proposed model for the production of a similar phenomenon referred to as sub-auroral ion drifts (SAIDs). The results of the comparison suggests that SARAS may result from a similar geophysical mechanism to that which produces SAID events, but probably occurs at a different time in the evolution of the event. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SpWea..15.1102V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SpWea..15.1102V">Ionosphere-thermosphere energy budgets for the ICME storms of March 2013 and 2015 estimated with GITM and observational proxies</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Verkhoglyadova, O. P.; Meng, X.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Lu, G. 2017-09-01 The ionosphere-thermosphere (IT) energy partitioning for the interplanetary coronal mass ejection (ICME) storms of 16-19 March 2013 and 2015 is estimated with the Global Ionosphere-Thermosphere Model (GITM), empirical models and proxies derived from in situ measurements. We focus on auroral heating, Joule heating, and thermospheric cooling. Solar wind data, F10.7, OVATION Prime model and the Weimer 2005 model are used to drive GITM from above. Thermospheric nitric oxide and carbon dioxide cooling emission powers and fluxes are estimated from TIMED/SABER measurements. Assimilative mapping of ionospheric electrodynamics (AMIE) estimations of hemispheric power and Joule heating are presented, based on data from global magnetometers, the AMPERE magnetic field data, SSUSI auroral images, and the SuperDARN radar network. Modeled Joule heating and auroral heating of the IT system are mostly controlled by external driving in the March 2013 and 2015 storms, while NO cooling persists into the storm recovery phase. The total heating in the model is about 1000 GW to 3000 GW. Additionally, we intercompare contributions in selected energy channels for five coronal mass ejection-type storms modeled with GITM. Modeled auroral heating shows reasonable agreement with AMIE hemispheric power and is higher than other observational proxies. Joule heating and infrared cooling are likely underestimated in GITM. We discuss challenges and discrepancies in estimating and global modeling of the IT energy partitioning, especially Joule heating, during geomagnetic storms. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012epsc.conf..449B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012epsc.conf..449B">Saturn and Earth polar oval position forecast by IMPEx InfrastructureWeb Services based on the Paraboloid magnetospheric model</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Blokhina, M. S.; Alexeev, I. I.; Belenkaya, E. S.; Kalegaev, V. V.; Barinova, V. O.; Khodachenko, M. L.; Topf, F. 2012-09-01 The Saturn and Earth auroral emissions have different generation mechanisms, however, both mechanisms are not understood very well till now (see [1]). Both of these phenomena have a long history of observations. For Saturn these are Hubble images and big onground telescope images, as well as the Cassini ones in recent time. For Earth these are the satellite visible and UV camera images and onground observations. In course of the EU-FP7 Project "Integrated Medium for Planetary Exploration" the Web services based on the paraboloid magnetospheric models were constructed . The model field lines tracing gives us a possibility to distinguish the closed and open field line bundles. Additionally, we can find a boundary between the dipole type field lines and determine a region of the tail-like field lines crossing the equatorial plane tailward from the inner edge of the tail current sheet. Projections of this boundary and of the boundary between open and closed field lines at the ionospheric level mark the terrestrial auroral oval boundaries. The final result depends on the solar wind parameters and the magnetospheric state. In the Earth's case we have the ACE solar wind monitoring data which should be used to determine the magnetospheric state (http://smdc.sinp.msu.ru/index.py? nav=paraboloid/index [Interactive Earth]). For Saturn we use the three levels of the solar wind dynamic pressure (http://smdc.sinp. msu.ru/index.py?nav=paraboloid/index [Interactive Saturn]). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM51E2543R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM51E2543R">Low Frequency Extensions of the Saturn Kilometric Radiation as a Proxy for Magnetospheric Dynamics.</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Reed, J.; Jackman, C. M.; Whiter, D. K.; Kurth, W. S.; Lamy, L. 2016-12-01 Saturn Kilometric Radiation (SKR) is a radio emission formed via the cyclotron maser instability on field aligned currents near the auroral regions of Saturn. The SKR has been found to respond to both internal and external driving, and to be linked to both solar wind compressions and magnetotail reconnection events. The radio emission is remotely sensed quasi-continuously and therefore offers the potential to be used as a proxy for magnetospheric activity when the spacecraft is not in an ideal viewing region for observing signatures of reconnection. In this work we use data taken by the Cassini magnetometer and radio and plasma wave sensor while Cassini was executing its deepest tail orbits in 2006. We characterise the behaviour of the SKR over this period and develop an automatic method for finding low frequency extensions (LFE), where the SKR emission extends down to lower frequencies below the main band. LFEs have been shown to occur in response to reconnection at Saturn (Jackman et al, 2009) and their appearance in Earth's analogous Auroral Kilometric Radiation (AKR) has been shown to coincide with substorm onset (e.g. Morioka et al, 2007). Using a new catalogue of LFEs we discuss their correlation with known tail reconnection events and solar wind shocks (as inferred from the use of propagated solar wind models). We also look at their properties such as length and recurrence rate, as well as their relationship to the planetary periodicities. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123..665L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123..665L">On the Role of Ionospheric Ions in Sawtooth Events</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lund, E. J.; Nowrouzi, N.; Kistler, L. M.; Cai, X.; Frey, H. U. 2018-01-01 Simulations have suggested that feedback of heavy ions originating in the ionosphere is an important mechanism for driving sawtooth injections. However, this feedback may only be necessary for events driven by coronal mass ejections (CMEs), whereas in events driven by streaming interaction regions (SIRs), solar wind variability may suffice to drive these injections. Here we present case studies of two sawtooth events for which in situ data are available in both the magnetotail (Cluster) and the nightside auroral region (FAST), as well as global auroral images (IMAGE). One event, on 1 October 2001, was driven by a CME; the other, on 24 October 2002, was driven by an SIR. The available data do not support the hypothesis that heavy ion feedback is necessary to drive either event. This result is consistent with simulations of the SIR-driven event but disagrees with simulation results for a different CME-driven event. We also find that in an overwhelming majority of the sawtooth injections for which Cluster tail data are available, the O+ observed in the tail comes from the cusp rather than the nightside auroral region, which further casts doubt on the hypothesis that ionospheric heavy ion feedback is the cause of sawtooth injections. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820061318&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2526%25231041','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820061318&hterms=1041&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3D%2526%25231041">Electric fields measured by ISEE-1 within and near the neutral sheet during quiet and active times</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cattell, C. A.; Mozer, F. S. 1982-01-01 An understanding of the physical processes occurring in the magnetotail and plasmasheet during different interplanetary magnetic field orientations and differing levels of ground magnetic activity is crucial for the development of a theory of energy transfer from the solar wind to the particles which produce auroral arcs. In the present investigation, the first observations of electric fields during neutral sheet crossings are presented, taking into account the statistical correlations of the interplanetary magnetic field direction and ground activity with the character of the electric field. The electric field data used in the study were obtained from a double probe experiment on the ISEE-1 satellite. The observations suggest that turbulent electric and magnetic fields are intimately related to plasma acceleration in the neutral sheet and to the processes which create auroral particles. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM23A2216H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM23A2216H">Time development of high-altitude auroral acceleration region plasma, potentials, and field-aligned current systems observed by Cluster during a substorm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hull, A. J.; Chaston, C. C.; Fillingim, M. O.; Mozer, F.; Frey, H. U. 2013-12-01 The auroral acceleration region is an integral link in the chain of events that transpire during substorms, and the currents, plasma and electric fields undergo significant changes driven by complex dynamical processes deep in the magnetotail. These auroral acceleration processes in turn accelerate and heat the plasma that ultimately leads to some of the most intense global substorm auroral displays. The complex interplay between field-aligned current system formation, the development of parallel electric fields, and resultant changes in the plasma constituents that occur during substorms within or just above the auroral acceleration zone remain unclear. We present Cluster multi-point observations within the high-altitude acceleration region (> 3 Re altitude) at key instances during the development of a substorm. Of particular emphasis is on the time-development of the plasma, potentials and currents that occur therein with the aim of ascertaining high-altitude drivers of substorm active auroral acceleration processes and auroral emission consequences. Preliminary results show that the initial onset is dominated by Alfvenic activity as evidenced by the sudden occurrence of relatively intense, short-spatial scale Alfvenic currents and attendant energy dispersed, counterstreaming electrons poleward of the growth-phase arc. The Alfvenic currents are locally planar structures with characteristic thicknesses on the order of a few tens of kilometers. In subsequent passages by the other spacecraft, the plasma sheet region became hotter and thicker via the injection of new hot, dense plasma of magnetospheric origins poleward of the pre-existing growth phase arc. In association with the heating and/or thickening of the plasma sheet, the currents appeared to broaden to larger scales as Alfven dominated activity gave way to either inverted-V dominated or mixed inverted-V and Alfvenic behavior depending on location. The transition from Alfven dominated to inverted-V dominated current systems was quite rapid, occurring in the span of a few minutes. These results suggest that the Alfvenic activity may be an important precursor and perhaps may be playing an essential role in the development of inverted-V arc systems that form during substorms. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/50520-some-topics-historical-episodes-geomagnetism-aeronomy','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/50520-some-topics-historical-episodes-geomagnetism-aeronomy">Some topics and historical episodes in geomagnetism and aeronomy</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Fukushima, N. 1994-10-01 The author provides historical perspective on work in the area of geomagnetism and aeronomy. He discusses early ideas discussed in the literature, work by Birkelund on current flows, ideas on the curl-freeness of the geomagnetic fields, studies of auroral records recorded by man, studies of magnetic storms, geomagnetic field measurements, and of late the wealth of satellite information of the magnetosphere and solar wind effects. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active">11</li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active">12</li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060044151&hterms=ionosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dionosphere','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060044151&hterms=ionosphere&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dionosphere">Impact of the Ionosphere on an L-band Space Based Radar</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chapin, Elaine; Chan, Samuel F.; Chapman, Bruce D.; Chen, Curtis W.; Martin, Jan M.; Michel, Thierry R.; Muellerschoen, Ronald J.; Pi, Xiaoqing; Rosen, Paul A. 2006-01-01 We have quantified the impact that the ionosphere would have on a L-band interferometric Synthetic Aperture Radar (SAR) mission using a combination of simulation, modeling, Global Positioning System (GPS) data collected during the last solar maximum, and existing spaceborne SAR data. We conclude that, except for high latitude scintillation related effects, the ionosphere will not significantly impact the performance of an L-band InSAR mission in an appropriate orbit. We evaluated the strength of the ionospheric irregularities using GPS scintillation data collected at Fairbanks, Alaska and modeled the impact of these irregularities on azimuth resolution, azimuth displacement, peak sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR). Although we predict that less than 5% of auroral zone data would show scintillation related artifacts, certain sites imaged near the equinoxes could be effected up to 25% of the time because the frequency of occurrence of scintillation is a strong function of season and local time of day. Our examination of ionospheric artifacts observed in InSAR data has revealed that the artifacts occur primarily in the polar cap data, not auroral zone data as was previously thought. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740010910','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740010910">Electric field measurements across the harang discontinuity. [of the auroral zone</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Maynard, N. C. 1974-01-01 The Harang discontinuity, the area separating the positive and negative bay regions in the midnight sector of the auroral zone, is a focal point for changes in behavior of many phenomena. Through this region the electric field rotates through the west from a basically northward field in the positive bay region to a basically southward field in the negative bay region, appearing as a reversal in a single axis measurement; 32 of these reversals have been identified in the OGO-6 data from November and December, 1969. The discontinuity is dynamic in nature, moving southward and steepening its latitudinal profile as magnetic activity is increased. As activity decreases it relaxes poleward and spreads out in latitudinal width. It occurs over several hours of magnetic local time. The boundary in the electric field data is consistent with the reversal of ground magnetic disturbances from a positive to negative bay condition. The discontinuity is present in the electric field data both during substorms and during quiet times and appears to define a pattern on which other effects can occur. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-10-04/pdf/2011-25533.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-10-04/pdf/2011-25533.pdf">76 FR 61342 - Foreign-Trade Zone 72 Temporary/Interim Manufacturing Authority Brevini Wind USA, Inc., (Wind...</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a> 2011-10-04 ... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [Docket T-3-2011] Foreign-Trade Zone 72 Temporary/Interim Manufacturing Authority Brevini Wind USA, Inc., (Wind Turbine Gear Boxes); Notice of Approval On... manufacturing (T/IM) authority, on behalf of Brevini Wind USA, Inc., to manufacture wind turbine gear boxes... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPhCS.524a2003S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPhCS.524a2003S">Investigation of the Impact of the Upstream Induction Zone on LIDAR Measurement Accuracy for Wind Turbine Control Applications using Large-Eddy Simulation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Simley, Eric; Y Pao, Lucy; Gebraad, Pieter; Churchfield, Matthew 2014-06-01 Several sources of error exist in lidar measurements for feedforward control of wind turbines including the ability to detect only radial velocities, spatial averaging, and wind evolution. This paper investigates another potential source of error: the upstream induction zone. The induction zone can directly affect lidar measurements and presents an opportunity for further decorrelation between upstream wind and the wind that interacts with the rotor. The impact of the induction zone is investigated using the combined CFD and aeroelastic code SOWFA. Lidar measurements are simulated upstream of a 5 MW turbine rotor and the true wind disturbances are found using a wind speed estimator and turbine outputs. Lidar performance in the absence of an induction zone is determined by simulating lidar measurements and the turbine response using the aeroelastic code FAST with wind inputs taken far upstream of the original turbine location in the SOWFA wind field. Results indicate that while measurement quality strongly depends on the amount of wind evolution, the induction zone has little effect. However, the optimal lidar preview distance and circular scan radius change slightly due to the presence of the induction zone. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JASTP.162...90S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JASTP.162...90S">Observation of Polar Mesosphere Summer Echoes using the northernmost MST radar at Eureka (80°N)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Swarnalingam, N.; Hocking, W.; Janches, D.; Drummond, J. 2017-09-01 We investigate long-term Polar Mesosphere Summer Echoes (PMSEs) observations conducted by the northernmost geographically located MST radar at Eureka (80°N, 86°W). While PMSEs are a well recognized summer phenomenon in the polar regions, previous calibrated studies at Resolute Bay and Eureka using 51.5 MHz and 33 MHz radars respectively, showed that PMSE backscatter signal strengths are relatively weak in the polar cap sites, compared to the auroral zone sites (Swarnalingam et al., 2009b; Singer et al., 2010). Complications arise with PMSEs in which the echo strength is controlled by the electrons, which are, in turn, influenced by heavily charged ice particles as well as the variability in the D-region plasma. In recent years, PMSE experiments were conducted inside the polar cap utilizing a 51 MHz radar located at Eureka. In this paper, we investigate calibrated observations, conducted during 2009-2015. Seasonal and diurnal variations of the backscatter signal strengths are discussed and compared to previously published results from the ALOMAR radar, which is a radar of similar design located in the auroral zone at Andenes, Norway (69°N, 16°E). At Eureka, while PMSEs are present with a daily occurrence rate which is comparable to the rate observed at the auroral zone site for at least two seasons, they show a great level of inter-annual variability. The occurrence rate for the strong echoes tends to be low. Furthermore, comparison of the absolute backscatter signal strengths at these two sites clearly indicates that the PMSE backscatter signal strength at Eureka is weak. Although this difference could be caused by several factors, we investigate the intensity of the neutral air turbulence at Eureka from the measurements of the Doppler spectrum of the PMSE backscatter signals. We found that the level of the turbulence intensity at Eureka is weak relative to previously reported results from three high latitude sites. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003916&hterms=Summer&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSummer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003916&hterms=Summer&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSummer">Observation of Polar Mesosphere Summer Echoes using the Northernmost MST Radar at Eureka (80 deg N)</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Swarnalingam, N.; Hocking, W.; Janches, D.; Drummond, J. 2017-01-01 We investigate long-term Polar Mesosphere Summer Echoes (PMSEs) observations conducted by the northern most geographically located MST radar at Eureka (80 deg N, 86 deg W). While PMSEs are a well recognized summer phenomenon in the polar regions, previous calibrated studies at Resolute Bay and Eureka using 51.5 MHz and33 MHz radars respectively, showed that PMSE backscatter signal strengths are relatively weak in the polar cap sites, compared to the auroral zone sites (Swarnalingam et al., 2009b; Singer et al., 2010). Complications arise with PMSEs in which the echo strength is controlled by the electrons, which are, in turn, influenced by heavily charged ice particles as well as the variability in the D-region plasma. In recent years, PMSE experiments were conducted inside the polar cap utilizing a 51 MHz radar located at Eureka. In this paper, we investigate calibrated observations, conducted during 2009-2015. Seasonal and diurnal variations of the backscatter signal strengths are discussed and compared to previously published results from the ALOMAR radar, which is a radar of similar design located in the auroral zone at Andenes, Norway (69 deg N, 16 deg E). At Eureka, while PMSEs are present with a daily occurrence rate which is comparable to the rate observed at the auroral zone site for at least two seasons, they show a great level of inter-annual variability. The occurrence rate for the strong echoes tends to be low. Furthermore, comparison of the absolute backscatter signal strengths at these two sites clearly indicates that the PMSE backscatter signal strength at Eureka is weak. Although this difference could be caused by several factors, we investigate the intensity of the neutral air turbulence at Eureka from the measurements of the Doppler spectrum of the PMSE backscatter signals. We found that the level of the turbulence intensity at Eureka is weak relative to previously reported results from three high latitude sites. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AAS...19915705O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AAS...19915705O">The Solar Connections Observatory for Planetary Environments (SCOPE):</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Oliversen, R.; Harris, W.; Ballester, G.; Bougher, S.; Broadfoot, L.; Combi, M.; Cravens, T.; Gombosi, T.; Herbert, F.; Joseph, C.; Kozyra, J.; Limaye, S.; Morgenthaler, J.; Paxton, L.; Roesler, F.; Sandel, W.; Ben Jaffel, L. 2001-12-01 The NASA Sun-Earth Connection theme roadmap calls for comparative study of how the planets and local interstellar medium (LISM) interact with and respond to changes in the solar wind and UV radiation field. Each planet interaction is unique and defined by solar input and local conditions of magnetic field strength and orientation, rotation rate, heliocentric distance, internal plasma, and ionospheric conductivity and circulation. Because the different elements of the environment respond to external and internal influences that are variable on many temporal and spatial scales, the study of a planetary system requires simultaneous understanding of the solar wind and diagnostics of the sun-planet interaction including auroral intensity and variation, upper atmospheric circulation and composition, and the distribution of neutrals and plasmas near the planet. The Solar Connections Observatory for Planetary Environments (SCOPE) is a mission to study Solar interactions from the level of planetary upper atmospheres to the heliopause. SCOPE consists of a binocular EUV/FUV telescope that provides high spatial resolution imaging, broadband spectro-imaging, and high-resolution H Ly-alpha line spectroscopy between 55-290 nm. SCOPE will study planetary environments as examples of the solar connection and map the distribution of interplanetary H and the interaction of LISM plasma with the solar wind at the heliopause. A key to the SCOPE approach is to include Earth in its research objectives. SCOPE will monitor terrestrial auroral energy deposition and leverage local measurements of the solar wind and propagation models to derive the expected conditions at Superior planets that will be observed in annual opposition campaigns. This will permit direct comparison of planetary and terrestrial responses to the same solar wind stream. Using a combination of observations and MHD models, SCOPE will isolate the different controlling parameters in each planet system and gain insight into the underlying physical processes that define the solar connection. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920059137&hterms=asian+american&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dasian%2Bamerican','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920059137&hterms=asian+american&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dasian%2Bamerican">How the effects of winds and electric fields in F2-layer storms vary with latitude and longitude - A theoretical study</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Mendillo, M.; He, X.-Q.; Rishbeth, H. 1992-01-01 The effects of thermospheric winds and electric fields on the ionospheric F2-layer are controlled by the geometry of the magnetic field, and so vary with latitude and longitude. A simple model of the daytime F2-layer is adopted and the effects at midlatitudes (25-65 deg geographic) of three processes that accompany geomagnetic storms: (1) thermospheric changes due to auroral heating; (2) equatorward winds that tend to cancel the quiet-day poleward winds; and (3) the penetration of magnetospheric electric fields are studied. At +/- 65 deg, the effects of heating and electric fields are strongest in the longitudes toward which the geomagnetic dipole is tilted, i.e., the North American and the South Indian Ocean sectors. Because of the proximity of the geomagnetic equator to the East Asian and South American sectors, the reverse is true at +/- 25 deg. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SSRv..200..495M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SSRv..200..495M">The MAVEN Solar Wind Electron Analyzer</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mitchell, D. L.; Mazelle, C.; Sauvaud, J.-A.; Thocaven, J.-J.; Rouzaud, J.; Fedorov, A.; Rouger, P.; Toublanc, D.; Taylor, E.; Gordon, D.; Robinson, M.; Heavner, S.; Turin, P.; Diaz-Aguado, M.; Curtis, D. W.; Lin, R. P.; Jakosky, B. M. 2016-04-01 The MAVEN Solar Wind Electron Analyzer (SWEA) is a symmetric hemispheric electrostatic analyzer with deflectors that is designed to measure the energy and angular distributions of 3-4600-eV electrons in the Mars environment. This energy range is important for impact ionization of planetary atmospheric species, and encompasses the solar wind core and halo populations, shock-energized electrons, auroral electrons, and ionospheric primary photoelectrons. The instrument is mounted at the end of a 1.5-meter boom to provide a clear field of view that spans nearly 80 % of the sky with ˜20° resolution. With an energy resolution of 17 % (Δ E/E), SWEA readily distinguishes electrons of solar wind and ionospheric origin. Combined with a 2-second measurement cadence and on-board real-time pitch angle mapping, SWEA determines magnetic topology with high (˜8-km) spatial resolution, so that local measurements of the plasma and magnetic field can be placed into global context. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900029446&hterms=polar+bear&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpolar%2Bbear','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900029446&hterms=polar+bear&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dpolar%2Bbear">A transient auroral event on the dayside</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Heikkila, Walter J.; Jorgensen, T. Stockflet T.; Lanzerotti, Louis J.; Maclennan, Carol G. 1989-01-01 A strong perturbation lasting about 10 min, beginning at 0930 UT on December 5, 1986, was recorded by high-latitude magnetometer stations in Greenland, Iqaluit, and the South Pole. Viking and Polar Bear satellite observations of the perturbation and observations of similar perturbations on the afternoon side in Svalbard, Heiss Island, and northern Siberia are also reported. It is suggested that the likely source of the perturbation is a magnetic disturbance in the solar wind observed by ISEE 1/2 and IMP 8. The perturbation is interpreted as an impulsive penetration of solar wind plasma on an interplanetary magnetic flux tube occurring through the magnetopause, ending in the low latitude boundary layer. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790059028&hterms=Wind+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DWind%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790059028&hterms=Wind+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DWind%2Benergy">Relationship between the growth of the ring current and the interplanetary quantity. [solar wind energy-magnetospheric coupling parameter correlation with substorm AE index</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Akasofu, S.-I. 1979-01-01 Akasofu (1979) has reported that the interplanetary parameter epsilon correlates reasonably well with the magnetospheric substorm index AE; in the first approximation, epsilon represents the solar wind coupled to the magnetosphere. The correlation between the interplanetary parameter, the auroral electrojet index and the ring current index is examined for three magnetic storms. It is shown that when the interplanetary parameter exceeds the amount that can be dissipated by the ionosphere in terms of the Joule heat production, the excess energy is absorbed by the ring current belt, producing an abnormal growth of the ring current index. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=GL-2002-001089&hterms=ftp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dftp%253A','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=GL-2002-001089&hterms=ftp&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dftp%253A">HUBBLE PROVIDES THE FIRST IMAGES OF SATURN'S AURORA (Top)</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 2002-01-01 This is the first image ever taken of bright aurorae at Saturn's northern and southern poles, as seen in far ultraviolet light by the Wide Field and Planetary Camera 2 aboard NASA's Hubble Space Telescope. Hubble resolves a luminous, circular band centered on the north pole, where an enormous auroral curtain rises as far as 1,200 miles (2,000 kilometers) above the cloudtops. This curtain changed rapidly in brightness and extent over the two hour period of our HST observations, though the brightest emissions remained at a position fixed in sun angle, near 'dawn' in the north auroral band. The image was taken on October 9, 1994, when Saturn was at a distance of 831 million miles (1.3 billion kilometers) from Earth. The aurora is produced as trapped charged particles precipitating from the magnetosphere collide with atmospheric gases -- molecular and atomic hydrogen in Saturn's case. As a result of the bombardment, Saturn's gases glow at far-ultraviolet wavelengths (110-160 nanometers) which are absorbed by the Earth's atmosphere, and so can only be observed from space-based telescopes. Saturn's magnetic field is nearly perfectly aligned with the planet's rotation, giving the auroral 'ring' its symmetry centered on the pole. (The southern aurora is faintly visible in this view despite the fact that Saturn's northern pole is now tilted slightly toward Earth.) The Hubble images demonstrate our capability to record from the Earth the auroral brightness and distribution about Saturn's poles, which will ultimately complement the in situ measurements of Saturn's magnetic field and charged particles to be made by the NASA/ESA Cassini spacecraft near the turn of the century. Study of the aurora on Saturn had its beginnings a few decades ago. The Pioneer 11 probe observed a far-ultraviolet brightening on Saturn's poles in 1979. Beginning in 1980, a series of spectroscopic observations by the International Ultraviolet Explorer (IUE) have sporadically detected emissions from Saturn's auroral zones. The Saturn flybys of the Voyager 1 and 2 spacecraft, in the early 1980s, found auroral emissions confined to a circumpolar ring. (Bottom) - For comparison, this is a visible-light color composite image of Saturn as seen by Hubble on December 1, 1994. Unlike the ultraviolet image, Saturn's familiar atmospheric belts and zones are clearly seen. The lower cloud deck is not visible at UV wavelengths because sunlight is reflected from higher in the atmosphere. Credits: J.T. Trauger (JPL), J.T. Clarke (Univ. of Michigan), the WFPC2 science team, and NASA Image files in GIF and JPEG format may be accessed on Internet via anonymous ftp from oposite.stsci.edu in /pubinfo. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860027614&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnetic%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860027614&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnetic%2Benergy">Explosive magnetic reconnection - Puzzle to be solved as the energy supply process for magnetospheric substorms?</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Akasofu, S.-I. 1985-01-01 It is pointed out that magnetospheric substorms are perhaps the most basic type of disturbances which occur throughout the magnetosphere. There is little doubt that the energy for magnetospheric substorms is delivered from the sun to the magnetosphere by the solar wind, and theoretical and observational studies have been conducted to uncover the processes associated with the energy transfer from the solar wind to the magnetosphere, and the subsequent processes leading to various magnetospheric substorm phenomena. It has been widely accepted that explosive magnetic reconnection supplies the energy for magnetospheric substorm processes. It is indicated that the auroral phenomena must be various manifestations of a large-scale electrical discharge process which is powered by the solar wind-magnetosphere dynamo. Certain problems regarding explosive magnetic reconnection are discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19970016609&hterms=nonlinear+dynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dnonlinear%2Bdynamics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19970016609&hterms=nonlinear+dynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dnonlinear%2Bdynamics">Nonlinear dynamics of the magnetosphere and space weather</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sharma, A. Surjalal 1996-01-01 The solar wind-magnetosphere system exhibits coherence on the global scale and such behavior can arise from nonlinearity on the dynamics. The observational time series data were used together with phase space reconstruction techniques to analyze the magnetospheric dynamics. Analysis of the solar wind, auroral electrojet and Dst indices showed low dimensionality of the dynamics and accurate prediction can be made with an input/output model. The predictability of the magnetosphere in spite of the apparent complexity arises from its dynamical synchronism with the solar wind. The electrodynamic coupling between different regions of the magnetosphere yields its coherent, low dimensional behavior. The data from multiple satellites and ground stations can be used to develop a spatio-temporal model that identifies the coupling between different regions. These nonlinear dynamical models provide space weather forecasting capabilities. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900018878','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900018878">Lower thermosphere (80-100 km) dynamics response to solar and geomagnetic activity: Overview</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kazimirovsky, E. S. 1989-01-01 The variations of solar and geomagnetic activity may affect the thermosphere circulation via plasma heating and electric fields, especially at high latitudes. The possibility exists that the energy involved in auroral and magnetic storms can produce significant changes of mesosphere and lower thermosphere wind systems. A study of global radar measurements of winds at 80 to 100 km region revealed the short term effects (correlation between wind field and geomagnetic storms) and long term variations over a solar cycle. It seems likely that the correlation results from a modification of planetary waves and tides propagated from below, thus altering the dynamical regime of the thermosphere. Sometimes the long term behavior points rather to a climatic variation with the internal atmospheric cause than to a direct solar control. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..11910144B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..11910144B">DEMETER observations of bursty MF emissions and their relation to ground-level auroral MF burst</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Broughton, M. C.; LaBelle, J.; Parrot, M. 2014-12-01 A survey of medium frequency (MF) electric field data from selected orbits of the Detection of Electro-Magnetic Emissions Transmitted from Earthquakes (DEMETER) spacecraft reveals 68 examples of a new type of bursty MF emissions occurring at high latitudes associated with auroral phenomena. These resemble auroral MF burst, a natural radio emission observed at ground level near local substorm onsets. Similar to MF burst, the bursty MF waves observed by DEMETER have broadband, impulsive frequency structure covering 1.5-3.0 MHz, amplitudes of 50-100 μV/m, an overall occurrence rate of ˜0.76% with higher occurrence during active times, and strong correlation with auroral hiss. The magnetic local time distribution of the MF waves observed by DEMETER shows peak occurrence rate near 18 MLT, somewhat earlier than the equivalent peak in the occurrence rate of ground level MF burst, though propagation effects and differences in the latitudes sampled by the two techniques may explain this discrepancy. Analysis of solar wind and SuperMAG data suggests that while the bursty MF waves observed by DEMETER are associated with enhanced auroral activity, their coincidence with substorm onset may not be as exact as that of ground level MF burst. One conjunction occurs in which MF burst is observed at Churchill, Manitoba, within 8 min of MF emissions detected by DEMETER on field lines approximately 1000 km southeast of Churchill. These observations may plausibly be associated with the same auroral event detected by ground level magnetometers at several Canadian observatories. Although it is uncertain, the balance of the evidence suggests that the bursty MF waves observed with DEMETER are the same phenomenon as the ground level MF burst. Hence, theories of MF burst generation in the ionosphere, such as beam-generated Langmuir waves excited over a range of altitudes or strong Langmuir turbulence generating a range of frequencies within a narrow altitude range, need to be revisited to see whether they predict in situ detection of MF burst. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMSH51B1283B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMSH51B1283B">Custom auroral electrojet indices calculated by using MANGO value-added services</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bargatze, L. F.; Moore, W. B.; King, T. A. 2009-12-01 A set of computational routines called MANGO, Magnetogram Analysis for the Network of Geophysical Observatories, is utilized to calculate customized versions of the auroral electrojet indices, AE, AL, and AU. MANGO is part of an effort to enhance data services available to users of the Heliophysics VxOs, specifically for the Virtual Magnetospheric Observatory (VMO). The MANGO value-added service package is composed of a set of IDL routines that decompose ground magnetic field observations to isolate secular, diurnal, and disturbance variations of magnetic field disturbance, station-by-station. Each MANGO subroutine has been written in modular fashion to allow "plug and play"-style flexibility and each has been designed to account for failure modes and noisy data so that the programs will run to completion producing as much derived data as possible. The capabilities of the MANGO service package will be demonstrated through their application to the study of auroral electrojet current flow during magnetic substorms. Traditionally, the AE indices are calculated by using data from about twelve ground stations located at northern auroral zone latitudes spread longitudinally around the world. Magnetogram data are corrected for secular variation prior to calculating the standard version of the indices but the data are not corrected for diurnal variations. A custom version of the AE indices will be created by using the MANGO routines including a step to subtract diurnal curves from the magnetic field data at each station. The custom AE indices provide more accurate measures of auroral electrojet activity due to isolation of the sunstorm electrojet magnetic field signiture. The improvements in the accuracy of the custom AE indices over the tradition indices are largest during the northern hemisphere summer when the range of diurnal variation reaches its maximum. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28139769','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28139769">Global solar wind variations over the last four centuries.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Owens, M J; Lockwood, M; Riley, P 2017-01-31 The most recent "grand minimum" of solar activity, the Maunder minimum (MM, 1650-1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth's magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840005024','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840005024">Solar wind variations in the 60-100 year period range: A review</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Feynman, J. 1983-01-01 The evidence for and against the reality of a solar wind variation in the period range of 60-100 years is reexamined. Six data sets are reviewed; sunspot numbers, geomagnetic variations, two auroral data sets and two (14)C data sets. These data are proxies for several different aspects of the solar wind and the presence or absence of 60-100 year cyclic behavior in a particular data set does not necessarily imply the presence or absence of this variation in other sets. It was concluded that two different analyses of proxy data for a particular characteristic of the heliospheric solar wind yielded conflicting results. This conflict can be resolved only by future research. It is also definitely confirmed that proxy data for the solar wind in the ecliptic at 1 A.U. undergo a periodic variation with a period of approximately 87 years. The average amplitude and phase of this variation as seen in eleven cycles of proxy data are presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..11612215D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..11612215D">Solar wind energy input during prolonged, intense northward interplanetary magnetic fields: A new coupling function</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Du, A. M.; Tsurutani, B. T.; Sun, W. 2011-12-01 Sudden energy release (ER) events in the midnight sector auroral zone during intense (B > 10 nT), long-duration (T > 3 h), northward (N = Bz > 0 nT) IMF magnetic clouds (MCs) during solar cycle 23 (SC23) have been examined in detail. The MCs with northward-then-southward (NS) IMFs were analyzed separately from MCs with southward-then-northward (SN) configurations. It is found that there is a lack of ER/substorms during the N field intervals of NS clouds. In sharp contrast, ER events do occur during the N field portions of SN MCs. From the above two results it is reasonable to conclude that the latter ER events represent residual energy remaining from the preceding S portions of the SN MCs. We derive a new solar wind-magnetosphere coupling function during northward IMFs: ENIMF = α N-1/12 V7/3 B1/2 + β V |Dstmin|. The first term on the right-hand side of the equation represents the energy input via “viscous interaction,” and the second term indicates the residual energy stored in the magnetotail. It is empirically found that the magnetotail/magnetosphere/ionosphere can store energy for a maximum of ˜4 h before it has dissipated away. This concept is defining one for ER/substorm energy storage. Our scenario indicates that the rate of solar wind energy injection into the magnetotail/magnetosphere/ionosphere for storage determines the potential form of energy release into the magnetosphere/ionosphere. This may be more important to understand solar wind-magnetosphere coupling than the dissipation mechanism itself (in understanding the form of the release). The concept of short-term energy storage is also applied for the solar case. It is argued that it may be necessary to identify the rate of energy input into solar magnetic loop systems to be able to predict the occurrence of solar flares. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active">12</li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active">13</li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17777779','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17777779">Remote sensing of the magnetic moment of uranus: predictions for voyager.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Hill, T W; Dessler, A J 1985-03-22 Power is supplied to a planet's magnetosphere from the kinetic energy of planetary spin and the energy flux of the impinging solar wind. A fraction of this power is available to drive numerous observable phenomena, such as polar auroras and planetary radio emissions. In this report our present understanding of these power transfer mechanisms is applied to Uranus to make specific predictions of the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and ultraviolet spectrometer (UVS) instruments aboard the Voyager spacecraft before its encounter with Uranus at the end of January 1986. The power available for these two phenomena is (among other factors) a function of the magnetic moment of Uranus. The date of earliest detectability also depends on whether the predominant power source for the magnetosphere is planetary spin or solar wind. The magnetic moment of Uranus is derived for each power source as a function of the date of first detection of radio emissions by the PRA instrument or auroral emissions by the UVS instrument. If we accept the interpretation of ultraviolet observations now available from the Earth-orbiting International Ultraviolet Explorer satellite, Uranus has a surface magnetic field of at least 0.6 gauss, and more probably several gauss, making it the largest or second-largest planetary magnetic field in the solar system. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA43C..08N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA43C..08N">Dynamics of ionospheric convection during disturbed periods observed by the mid-latitude SuperDARN radars in the premidnight and postmidnight sector</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nishitani, N.; Hori, T.; Baker, J. B.; Ruohoniemi, J. M.; Shepherd, S. G.; Bristow, W. A.; Matsuoka, A.; Teramoto, M. 2017-12-01 Sub-Auroral Polarization Streams (SAPS) are one of the main disturbance signatures in the ionospheric convection at subauroral latitudes. Their generation is related to a wide variety of factors such as ring current distribution, solar wind / magnetospheric conditions, ionospheric conductivity etc. Expansion of the Super Dual Auroral Radar Network (SuperDARN) field of view into mid-latitudes and the launch of the inner magnetosphere spacecraft made it possible to study the SAPS dynamics in the framework of the global convection and magnetospheric disturbances. In this paper we discuss one event of the SAPS and concurrent convection signatures on Apr 4, 2017, observed by the mid-latitude SuperDARN radars. Together with the enhancement / decay of the SAPS in the premidnight sector, the mid-latitude SuperDARN radar observed the intensification / weakening of the eastward convective flows in the postmidnight sector. Furthermore, these eastward flows were enhanced together with the magnetic perturbations observed by the ERG / Arase satellite located in the same local time sector, probably associated with the substorm expansion onset. Detailed study of the ionospheric convection dynamics including SAPS, as well as their relation to solar wind / IMF condition changes, or substorm / storm developments will be reported in the presentation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720026114','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720026114">Planetary X ray experiment: Supporting research for outer planets mission: Experiment definition phase</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hurley, K.; Anderson, K. A. 1972-01-01 Models of Jupiter's magnetosphere were examined to predict the X-ray flux that would be emitted in auroral or radiation zone processes. Various types of X-ray detection were investigated for energy resolution, efficiency, reliability, and background. From the model fluxes it was determined under what models Jovian X-rays could be detected. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990018629&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990018629&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2Benergy">Spatial and Temporal Energy Characterization of Precipitating Electrons for the January 10th, 1997 Magnetic Cloud Event</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spann, J. F., Jr.; Germany, G. A.; Brittnacher, M. J.; Parks, G. K.; Elsen, R. 1997-01-01 The January 10-11, 1997 magnetic cloud event provided a rare opportunity to study auroral energy deposition under varying but intense IMF conditions. The Wind spacecraft located about 100 RE upstream monitored the IMF and plasma parameters during the passing of the cloud. The Polar Ultraviolet Imager (UVI) observed the aurora[ precipitation during the first encounter of the cloud with Earth's magnetosphere and during several subsequent substorm events. The UVI has the unique capability of measuring the energy flux and characteristic energy of the precipitating electrons through the use of narrow band filters that distinguish short and long wavelength molecular nitrogen emissions. The spatial and temporal characteristics of the precipitating electron energy will be discussed beginning with the inception of the event at the Earth early January 1 Oth and continuing through the subsidence of auroral activity on January 11th. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000021211','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000021211">UCLA IGPP Space Plasma Simulation Group</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 1998-01-01 During the past 10 years the UCLA IGPP Space Plasma Simulation Group has pursued its theoretical effort to develop a Mission Oriented Theory (MOT) for the International Solar Terrestrial Physics (ISTP) program. This effort has been based on a combination of approaches: analytical theory, large scale kinetic (LSK) calculations, global magnetohydrodynamic (MHD) simulations and self-consistent plasma kinetic (SCK) simulations. These models have been used to formulate a global interpretation of local measurements made by the ISTP spacecraft. The regions of applications of the MOT cover most of the magnetosphere: the solar wind, the low- and high-latitude magnetospheric boundary, the near-Earth and distant magnetotail, and the auroral region. Most recent investigations include: plasma processes in the electron foreshock, response of the magnetospheric cusp, particle entry in the magnetosphere, sources of observed distribution functions in the magnetotail, transport of oxygen ions, self-consistent evolution of the magnetotail, substorm studies, effects of explosive reconnection, and auroral acceleration simulations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12212090V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12212090V">Long-Term Variability of Jupiter's Magnetodisk and Implications for the Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Vogt, Marissa F.; Bunce, Emma J.; Nichols, Jonathan D.; Clarke, John T.; Kurth, William S. 2017-12-01 Observations of Jupiter's UV auroral emissions collected over several years show that the ionospheric positions of the main emission and the Ganymede footprint can vary by as much as 3° in latitude. One explanation for this shift is a change of Jupiter's current sheet current density, which would alter the amount of field line stretching and displace the ionospheric mapping of field lines from a given radial distance in the magnetosphere. In this study we measure the long-term variability of Jupiter's magnetodisk using Galileo magnetometer data collected from 1996 to 2003. Using the Connerney et al. (1981) current sheet model, we calculate the current sheet density parameter that gives the best fit to the data from each orbit and find that the current density parameter varies by about 15% of its average value during the Galileo era. We investigate possible relationships between the observed current sheet variability and quantities such as Io's plasma torus production rate inferred from volcanic activity and external solar wind conditions extrapolated from data at 1 AU but find only a weak correlation. Finally, we trace Khurana (1997) model field lines to show that the observed changes in Jupiter's current sheet are sufficient to shift the ionospheric footprint of Ganymede and main auroral emission by a few degrees of latitude, consistent with the magnitude of auroral variability observed by Hubble Space Telescope (HST). However, we find that the measured auroral shifts in HST images are not consistent with concurrent changes in the current density parameter measured by Galileo. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990089688&hterms=hydra&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhydra','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990089688&hterms=hydra&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhydra">Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitations, Plasma Waves, and Convection Observed by POLAR</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hirahara, M.; Horwitz, J. L.; Moore, T. E.; Germany, G. A.; Spann, J. F.; Peterson, W. K.; Shelley, E. G.; Chandler, M. O.; Giles, B. L.; Craven, P. D.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_19990089688'); toggleEditAbsImage('author_19990089688_show'); toggleEditAbsImage('author_19990089688_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_19990089688_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_19990089688_hide"> 1997-01-01 The POLAR satellite often observes upflowing ionospheric ions (UFls) in and near the auroral oval on southern perigee (approximately 5000 km altitude) passes. We present the UFI features observed by the thermal ion dynamics experiment (TIDE) and the toroidal imaging mass-angle spectrograph (TIMAS) in the dusk-dawn sector under two different geomagnetic activity conditions in order to elicit their relationships with auroral forms, wave emissions, and convection pattern from additional POLAR instruments. During the active interval, the ultraviolet imager (UVI) observed a bright discrete aurora on the dusk side after the substorm onset and then observed a small isolated aurora form and diffuse auroras on the dawn side during the recovery phase. The UFls showed clear conic distributions when the plasma wave instrument (PWI) detected strong broadband wave emissions below approximately 10 kHz, while no significant auroral activities were observed by UVI. At higher latitudes, the low-energy UFI conics gradually changed to the polar wind component with decreasing intensity of the broadband emissions. V-shaped auroral kilometric radiation (AKR) signatures observed above approximately 200 kHz by PWI coincided with the region where the discrete aurora and the UFI beams were detected. The latitude of these features was lower than that of the UFI conics. During the observations of the UFI beams and conics, the lower-frequency fluctuations observed by the electric field instrument (EFI) were also enhanced, and the convection directions exhibited large fluctuations. It is evident that large electrostatic potential drops produced the precipitating electrons and discrete auroras, the UFI beams, and the AKR, which is also supported by the energetic plasma data from HYDRA. Since the intense broadband emissions were also observed with the UFIs. the ionospheric ions could be energized transversely before or during the parallel acceleration due to the potential drops. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA33A2574N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA33A2574N">Gravity Wave Detection through All-sky Imaging of Airglow</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nguyen, T. V.; Martinez, A.; Porat, I.; Hampton, D. L.; Bering, E., III; Wood, L. 2017-12-01 Airglow, the faint glow of the atmosphere, is caused by the interaction of air molecules with radiation from the sun. Similarly, the aurora is created by interactions of air molecules with the solar wind. It has been shown that airglow emissions are altered by gravity waves passing through airglow source region (100-110km), making it possible to study gravity waves and their sources through airglow imaging. University of Houston's USIP - Airglow team designed a compact, inexpensive all-sky imager capable of detecting airglow and auroral emissions using a fisheye lens, a simple optical train, a filter wheel with 4 specific filters, and a CMOS camera. This instrument has been used in USIP's scientific campaign in Alaska throughout March 2017. During this period, the imager captured auroral activity in the Fairbanks region. Due to lunar conditions and auroral activity images from the campaign did not yield visible signs of airglow. Currently, the team is trying to detect gravity wave patterns present in the images through numerical analysis. Detected gravity wave patterns will be compared to local weather data, and may be used to make correlations between gravity waves and weather events. Such correlations could provide more data on the relationship between the mesosphere and lower layers of the atmosphere. Practical applications of this research include weather prediction and detection of air turbulence. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.3997L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.3997L">The aurorae of Uranus past equinox</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lamy, L.; Prangé, R.; Hansen, K. C.; Tao, C.; Cowley, S. W. H.; Stallard, T. S.; Melin, H.; Achilleos, N.; Guio, P.; Badman, S. V.; Kim, T.; Pogorelov, N. 2017-04-01 The aurorae of Uranus were recently detected in the far ultraviolet with the Hubble Space Telescope (HST) providing a new, so far unique, means to remotely study the asymmetric Uranian magnetosphere from Earth. We analyze here two new HST Uranus campaigns executed in September 2012 and November 2014 with different temporal coverage and under variable solar wind conditions numerically predicted by three different MHD codes. Overall, the HST images taken with the Space Telescope Imaging Spectrograph reveal auroral emissions in three pairs of successive images (one pair acquired in 2012 and two in 2014), hence 6 additional auroral detections in total, including the most intense Uranian aurorae ever seen with HST. The detected emissions occur close the expected arrival of interplanetary shocks. They appear as extended spots at southern latitudes, rotating with the planet. They radiate 5-24 kR and 1.3-8.8 GW of ultraviolet emission from H2, last for tens of minutes and vary on timescales down to a few seconds. Fitting the 2014 observations with model auroral ovals constrains the longitude of the southern (northern) magnetic pole to 104 ± 26° (284 ± 26°) in the Uranian Longitude System. We suggest that the Uranian near-equinoctial aurorae are pulsed cusp emissions possibly triggered by large-scale magnetospheric compressions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P34C..03L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P34C..03L">The aurorae of Uranus past equinox</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lamy, L. 2017-12-01 The aurorae of Uranus were recently detected in the far ultraviolet with the Hubble Space Telescope (HST) providing a new, so far unique, means to remotely study the asymmetric Uranian magnetosphere from Earth. We analyze here two new HST Uranus campaigns executed in September 2012 and November 2014 with different temporal coverage and under variable solar wind conditions numerically predicted by three different MHD codes. Overall, the HST images taken with the Space Telescope Imaging Spectrograph reveal auroral emissions in three pairs of successive images (one pair acquired in 2012 and two in 2014), hence 6 additional auroral detections in total, including the most intense Uranian aurorae ever seen with HST. The detected emissions occur close the expected arrival of interplanetary shocks. They appear as extended spots at southern latitudes, rotating with the planet. They radiate 5-24 kR and 1.3-8.8 GW of ultraviolet emission from H2, last for tens of minutes and vary on timescales down to a few seconds. Fitting the 2014 observations with model auroral ovals constrains the longitude of the southern (northern) magnetic pole to 104+/-26deg (284+/-26deg) in the Uranian Longitude System. We suggest that the Uranian near-equinoctial aurorae are pulsed cusp emissions possibly triggered by large-scale magnetospheric compressions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title24-vol5/pdf/CFR-2010-title24-vol5-sec3285-405.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title24-vol5/pdf/CFR-2010-title24-vol5-sec3285-405.pdf">24 CFR 3285.405 - Severe wind zones.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a> 2010-04-01 ... DEVELOPMENT MODEL MANUFACTURED HOME INSTALLATION STANDARDS Anchorage Against Wind § 3285.405 Severe wind zones. When any part of a home is installed within 1,500 feet of a coastline in Wind Zones II or III, the manufactured home must be designed for the increased requirements, as specified on the home's data plate (refer... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AnGeo..35.1165P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AnGeo..35.1165P">Evidence of prompt penetration electric fields during HILDCAA events</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pereira Silva, Regia; Sobral, Jose Humberto Andrade; Koga, Daiki; Rodrigues Souza, Jonas 2017-10-01 High-intensity, long-duration continuous auroral electrojet (AE) activity (HILDCAA) events may occur during a long-lasting recovery phase of a geomagnetic storm. They are a special kind of geomagnetic activity, different from magnetic storms or substorms. Ionized particles are pumped into the auroral region by the action of Alfvén waves, increasing the auroral current system. The Dst index, however, does not present a significant downward swing as it occurs during geomagnetic storms. During the HILDCAA occurrence, the AE index presents an intense and continuous activity. In this paper, the response of Brazilian equatorial ionosphere is studied during three HILDCAA events that occurred in the year of 2006 (the descending phase of solar cycle 23) using the digisonde data located at São Luís, Brazil (2.33° S, 44.2° W; dip latitude 1.75° S). Geomagnetic indices and interplanetary parameters were used to calculate a cross-correlation coefficient between the Ey component of the interplanetary electric field and the F2 electron density peak height variations during two situations: the first of them for two sets daytime and nighttime ranges, and the second one for the time around the pre-reversal enhancement (PRE) peak. The results showed that the pumping action of particle precipitation into the auroral zone has moderately modified the equatorial F2 peak height. However, F2 peak height seems to be more sensitive to HILDCAA effects during PRE time, showing the highest variations and sinusoidal oscillations in the cross-correlation indices. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....13380K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....13380K">OH line selection for nadir airglow gravity wave imaging in the auroral zone</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kumer, J. B.; Hecht, J.; Geballe, T. R.; Mergenthaler, J. L.; Rinaldi, M.; Claflin, E. S.; Swenson, G. R. 2003-04-01 For satellite borne nadir OH airglow wave imaging in the auroral zone the observed lines must be strong enough to give good signal to noise, coincident with strong atmospheric absorption lines to suppress structure in the image due to reflection of airglow and moonlight from tops of clouds and from high altitude terrain, and in a spectral region coincident with relatively weak aurora that its contribution to the observed structure can be corrected by data obtained in a guard band containing relatively strong auroral emission, and relatively weak, or no airglow. OH airglow spectra observed from high altitude, in our case Mauna Kea by the UKIRT CGS4 grating instrument, (see website http://www.jach.hawaii.edu/JACpublic/UKIRT/instruments/cgs4/maunakea/ohlines.html) provide an opportunity to identify lines that ARE NOT observed at that high altitude. These are most absorbed in the earths atmosphere. These occur in the regions near 1400 and 1900 nm of strong water vapor absorption. Our preliminary determination is that the 7-5 p1(2) line at 1899.01 nm and the p1(3) at 1911.41 nm are the best candidates. These are missing in the observed spectra, and this is confirmed by running FASCODE transmission calculations from top of Mauna Kea to space at .01 cm-1 resolution. Similar calculations for conditions at which the high resolution Kitt peak atlas data were taken confirmed the calculations. OH line positions and relative strengths within the band were derived from the HITRAN data base, and transmitted lines in the 7-5 band were used to determine the strength of these lines. Each are the order 10 kR, and are about four to six times brighter than atmospheric absorbed candidate lines in the 1400 nm region. Also, the aurora in the 1900nm region is considerably weaker than in the 1400nm region. In fact the region 1351 to 1358 contains relatively strong aurora, and practically no airglow, and is candidate for an instrumental auroral guard band. The nadir imaging instrument which utilizes a radiatively cooled near infrared two dimensional array detector will be described. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA227690','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA227690">A Comparison of Optically Measured and Radar-Derived Horizontal Neutral Winds</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1990-01-01 observations of large-scale gravity waves or3 traveling ionospheric disturbances by Testud [1970], Iunsucker [1982]. The contributions of the parallel...increase in Kp, in agreement with previous findings of excitation by auroral processes [ Testud , 1970; lHernandez and Roble, 1976b; lunsucker, 19821...and 0+ and H+ ions, J. Geophys. Res., 69, 2349-2355, 1964. Testud , J., Gravity waves generated during magnetic substorms, J. Atmos. Terr. Phys., 32 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160005726&hterms=CAPS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCAPS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160005726&hterms=CAPS&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DCAPS">VISIONS: Remote Observations of a Spatially-Structured Filamentary Source of Energetic Neutral Atoms near the Polar Cap Boundary During an Auroral Substorm</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Collier, Michael R.; Chornay, D.; Clemmons, J.; Keller, J. W.; Klenzing, J.; Kujawski, J.; McLain, J.; Pfaff, R.; Rowland, D.; Zettergren, M. 2015-01-01 We report initial results from the VISualizing Ion Outflow via Neutral atom imaging during a Substorm (VISIONS) rocket that flew through and near several regions of enhanced auroral activity and also sensed regions of ion outflow both remotely and directly. The observed neutral atom fluxes were largest at the lower energies and generally higher in the auroral zone than in the polar cap. In this paper, we focus on data from the latter half of the VISIONS trajectory when the rocket traversed the polar cap region. During this period, many of the energetic neutral atom spectra show a peak at 100 electronvolts. Spectra with peaks around 100 electronvolts are also observed in the Electrostatic Ion Analyzer (EIA) data consistent with these ions comprising the source population for the energetic neutral atoms. The EIA observations of this low energy population extend only over a few tens of kilometers. Furthermore, the directionality of the arriving energetic neutral atoms is consistent with either this spatially localized source of energetic ions extending from as low as about 300 kilometers up to above 600 kilometers or a larger source of energetic ions to the southwest. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770026777','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770026777">The energy balance of the nighttime thermosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Glenar, D. A. 1977-01-01 The discrepancy between the input from the day hemisphere and the observed loss rates is discussed in terms of ion-neutral processes and gravity wave inputs. There has been considerable speculation as to the energy balance of the thermosphere and in particular about the fraction of the total energy input supplied by ultraviolet radiation. The problem is considerably simplified by considering the energy balance of the nighttime hemisphere alone. Sunrise and sunset vapor trail measurements provide data on the wind systems at the terminator boundary, and temperature measurements provide information on the vertical energy conduction. North-south winds from high latitude vapor trail measurements provide a measure of the energy input from auroral processes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.2146S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.2146S">Effect of the solar wind and interplanetary magnetic field parameter variations to the enhancement and dynamics of auroral electrojet during superstrong magnetic storms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Solovyev, Stepan; Boroev, Roman; Moiseyev, Alexey; Du, Aimin; Yumoto, Kiyohumi According to the global ground geomagnetic observations in the six meridian chains and analysis of satellite measurements the auroral elektrojet features at various conditions in the solar wind (SW) and the IMF: during a sharp rise of dynamic pressure up to 15-60 nPa and variations in the intensity and sign of the IMF Bz-component to -40 --50 nT. The data obtained during super strong magnetic storms of October 29-30, 2003, November 20-21, 2003, November 07-08, 2004 and November 09-10, 2004 (Dst = -300 --400 nT) are analysed. The following scientific results are obtained: • It is shown that a sharp increase of the SW dynamic pressure (Pd) and the excitation of a sudden impulse (SC) during IMF Bz negative (Bz<0) leads to a simultaneous (with accuracy 1-3 min) increase of DP2 current system and the intensity of the western elec-trojet (Jw) in a broad sector of longitudes and expansion of Jw to the pole up to the polar cap latitudes with the velocity of VN = 1-3 km/s. • It is found that during the sharp rise of Pd up to 60 nPa for IMF Bz positive (Bz>0) 35 nT is the amplification of eastward magnetopause currents and DP2 current system are observed. Strengthening and dynamics of the westward electrojet is not observed. • We find that during periods of intensity growth of negative values of IMF Bz to -50 nT within a few hours there is a shift of the centers of auroral electrojet to the equator up to latitudes about 10-20 degrees along the meridian with a speed of 1-4 km/s with a simultaneous amplifications of Jw repeated in 1-2 hours with a duration of 1-2 hours at latitudes from low to auroral latitudes and with a possible extension to electrojets up to the polar cap latitudes and the abrupt extension of the subsequent Jw electrojets localization region by azimuth. • It is shown that after the electrojet displacement to the equator during southward direc-tion of IMF Bz and enhancement of the SW electric field the IMF Bz turning to the north accompanied by the poleward expansion of Jw electrojet at a speed of 1 km/s in a wide range of longitudes is observed. • It is found that the electrojet expansion to the pole during superstorms often occurs up to the polar cap latitudes due to the extension of the precipitating particles and increased ionospheric conductivity region from the low and auroral latitudes, but not due to the movement of localized westward electrojet along the meridian, as is the case in the substorm. The report discusses the possible causes of the dynamics of auroral electrojets under different geophysical conditions. This work was supported by the Presidium of the Russian Academy of Sciences (program 16, part 3), by the RFBR grant No.09-05-98546 and also supported by the SB RAS project No.69. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814432R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814432R">Modelling impacts of offshore wind farms on trophic web: the Courseulles-sur-Mer case study</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Raoux, Aurore; Pezy, Jean-Philippe; Dauvin, Jean-Claude; Tecchio, samuele; Degraer, Steven; Wilhelmsson, Dan; Niquil, Nathalie 2016-04-01 The French government is planning the construction of three offshore wind farms in Normandy. These offshore wind farms will integrate into an ecosystem already subject to a growing number of anthropogenic disturbances such as transportation, fishing, sediment deposit, and sediment extraction. The possible effects of this cumulative stressors on ecosystem functioning are still unknown, but they could impact their resilience, making them susceptible to changes from one stable state to another. Understanding the behaviour of these marine coastal complex systems is essential in order to anticipate potential state changes, and to implement conservation actions in a sustainable manner. Currently, there are no global and integrated studies on the effects of construction and exploitation of offshore wind farms. Moreover, approaches are generally focused on the conservation of some species or groups of species. Here, we develop a holistic and integrated view of ecosystem impacts through the use of trophic webs modelling tools. Trophic models describe the interaction between biological compartments at different trophic levels and are based on the quantification of flow of energy and matter in ecosystems. They allow the application of numerical methods for the characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA). These indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitive to different impacts on marine ecosystems. We present here in detail the strategy for analysing the potential environmental impacts of the construction of the Courseulles-sur-Mer offshore wind farm (Bay of Seine) such as the reef effect through the use of the Ecopath with Ecosim software. Similar Ecopath simulations will be made in the future on the Le Tréport offshore wind farm site. Results will contribute to a better knowledge of the impacts of the offshore wind farms on ecosystems. They also allow to define recommendations for environmental managers and industry in terms of monitoring the effects of Marine Renewable Energy, not only locally, but also on other sites, national and European levels. Finally, this approach could contribute to a better social acceptability of Marine Renewable Energy projects allowing a holistic vision of all pressures on ecosystems. Keywords: Marine Renewable Energies, trophic model Contact author: Aurore Raoux, UNICAEN, raoux.aurore@gmail.com </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870050077&hterms=Rocket+diagrams&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRocket%2Bdiagrams','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870050077&hterms=Rocket+diagrams&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRocket%2Bdiagrams">ELF waves and ion resonances produced by an electron beam emitting rocket in the ionosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Winckler, J. R.; Abe, Y.; Erickson, K. N. 1986-01-01 Results are reported from the ECHO-6 electron-beam-injection experiment, performed in the auroral-zone ionosphere on March 30, 1983 using a sounding rocket equipped with two electron guns and a free-flying plasma-diagnostics instrument package. The data are presented in extensive graphs and diagrams and characterized in detail. Large ELF wave variations, superposed on the strong beam-sector-directed quasi-dc component, are observed in the 100-eV beam-induced plasma when the beam is injected in a transverse spiral, but not when it is injected upward parallel to the magnetic-field line. ELF activity is found to be suppressed whenever the rocket passed through field lines with auroral activity, suggesting that the waves are produced by the interaction of the beam potentials, plasma currents, and return currents neutralizing the accelerator payload. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P31C2826M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P31C2826M">Jovian Space Weather in the Juno Era: Remote Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> MacDowall, R. J.; Reiner, M. J.; Farrell, W. M.; Connerney, J. E. P. 2017-12-01 Jupiter is a large and rapidly rotating planet with a strong magnetic field, its magnetospheric dynamics only minimally influenced by the solar wind and interplanetary magnetic field (IMF). Yet, there are a number of manifestations of the Jovian magnetospheric interaction with elements of the solar wind and IMF. Variations in Jovian radio emissions are a prime example (Reiner et al. 2000, Zarka et al. 2004, Bose et al. 2008, Panchenko et al. 2012), as are auroral variations monitored in the infrared and ultraviolet.We present a review of the many journal papers that have examined the relationship between solar wind and IMF conditions (at the Jovian magnetosphere) and the Jovian radio burst variations and other associated phenomena.We present recent results from the joint observations by STEREO WAVES and WIND WAVES of Jovian radio emissions in the band of 1 - 15 MHz. The goal is to add a remote radio observation component to the determination of Jovian space weather, of particular use for data analysis by spacecraft orbiting the planet within the magnetosphere. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active">13</li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active">14</li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050180713&hterms=comparative&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcomparative','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050180713&hterms=comparative&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dcomparative">A Comparative View of X-rays from the Solar System</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bhardwaj, Anil; Elsner, Ron; Gladstone, Randy; Cravens, Tom; Waite, Hunter; Branduardi-Raymont, Graziella; Ostgaard, Nikolai; Dennerl, Konrad; Lisse, Carey; Kharchenko, Vasili 2005-01-01 With the advent of sophisticated X-ray observatories, viz., Chandra and XMM-Newton, the field of planetary X-ray astronomy is advancing at a faster pace. Several new solar system objects are now know to shine in X-rays at energies generally below 2 keV. Jupiter, Saturn, and Earth, all three magnetized planets, have been observed by Chandra and XMM-Newton. At Jupiter, both auroral and non-auroral disk X-ray emissions have been observed. The first soft X-ray observation of Earth's aurora by Chandra shows that it is highly variable. X-rays have been detected from Saturn's disk, but no convincing evidence of X-ray aurora has been seen. Several comets have been observed in X-rays by Chandra and XMM-Newton. Cometary X-rays are produced due to change exchange of solar wind ions with cold cometary neutrals. Soft X-rays have also been observed from Venus, Mars, Moon, Io, Europa, Io plasma torus, and heliosphere. The non-auroral X-ray emissions from Jupiter, Saturn, and Earth, and those from sunlit disk of Mars, Venus, and Moon are produced due to scattering of solar X-rays. The spectral characteristics of X-ray emission from comets, heliosphere, darkside of Moon, and Martian halo are quite similar, but they appear to be quite different from those of Jovian auroral X-rays. The X- ray aurora on Earth is generated by electron bremsstrahlung and on Jupiter by precipitation of highly-ionized energetic heavy ions. In this paper we will present a comparative overview of X-ray emission from different solar system objects and make an attempt to synthesize a coherent picture. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.4723H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.4723H">Field-aligned current and auroral Hall current characteristics derived from the Swarm constellation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Huang, Tao; Wang, Hui; Hermann, Luehr 2017-04-01 On the basis of field-aligned currents (FACs) and Hall currents derived from high-resolution magnetic field data of the Swarm constellation the average characteristics of these two current systems in the auroral regions are comprehensively investigated by statistical methods. This is the first study considering both current types simultaneously and for both hemispheres. The FAC distribution, derived from the Swarm dual-spacecraft approach, reveals the well-known features of Region 1 (R1) and Region 2 (R2) FACs. At high latitudes, Region 0 (R0) FACs appear on the dayside. Their direction depends on the orientation of the interplanetary magnetic field (IMF) By component. Of particular interest is the distribution of auroral Hall currents. The most prominent auroral electrojets are found to be closely controlled by the solar wind input. But there is no dependence on the IMF By orientation. The eastward electrojet is about twice as strong in summer as in winter. Conversely, the westward electrojet shows less dependence on season. Part of the electrojet current is closed over the polar cap. Here the seasonal variation of conductivity mainly controls the current density. There is a clear channeling of return currents over the polar cap. Depending on IMF By orientation most of the current is flowing either on the dawn or dusk side. The direction of Hall currents in the noon sector depends directly on the orientation of the IMF By. This is true for both signs of the IMF Bz component. But largest differences between summer and winter seasons are found for northward IMF Bz. Around the midnight sector the westward substorm electrojet is dominating. As expected, it is highly dependent on magnetic activity, but shows only little response to the IMF By polarity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM41A2684O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM41A2684O">Evolution of asymmetrically displaced footpoints during substorms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ohma, A.; Østgaard, N.; Laundal, K.; Reistad, J.; Tenfjord, P.; Snekvik, K.; Fillingim, M. O. 2017-12-01 It is well established that a transverse (y) component in the interplanetary magnetic field (IMF) induces a By component in the closed magnetosphere through asymmetric loading and/or redistribution of magnetic flux. Simultaneous images of the aurora in the two hemispheres have revealed that conjugate auroral features are displaced longitudinally during such conditions, indicating that the field-lines are displaced from their symmetric configuration. Although the direction and magnitude of this displacement show correlations with IMF clock angle and dipole tilt, events show large temporal and spatial variability of this displacement. For instance, it is not clear how substorms affect the displacement.In a previous case study, Østgaard et al. [2011] demonstrated that displaced auroral forms, associated with the present IMF orientation, returned to a more symmetric configuration during the expansion phase of two substorms. Using IMAGE and Polar, we have identified multiple events where conjugate images during substorms are available. By visual inspection and by applying correlation analysis, we identify conjugate auroral features and investigate how the asymmetry evolves during the substorm phases. We find that the system returns to a more symmetric state during the substorm expansion and early recovery phase, in agreement with the earlier published result. This is also true for the events where the solar wind driving is stable, indicating that the asymmetric displacement is indeed reduced or removed by the substorm. This can be interpreted as the result of increased reconnection rate in the magnetotail during the substorm expansion phase, which reduces the asymmetric lobe pressure.Østgaard, N., B. K. Humberset, and K. M. Laundal (2011), Evolution of auroral asymmetries in the conjugate hemi-spheres during two substorms, Geophys. Res. Lett., 38, L03101, doi:10.1029/2010GL046057. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017amos.confE..94J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017amos.confE..94J">Research to Operations Transition of an Auroral Specification and Forecast Model</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jones, J.; Sanders, S.; Davis, B.; Hedrick, C.; Mitchell, E. J.; Cox, J. M. Aurorae are generally caused by collisions of high-energy precipitating electrons and neutral molecules in Earth’s polar atmosphere. The electrons, originating in Earth’s magnetosphere, collide with oxygen and nitrogen molecules driving them to an excited state. As the molecules return to their normal state, a photon is released resulting in the aurora. Aurora can become troublesome for operations of UHF and L-Band radars since these radio frequencies can be scattered by these abundant free electrons and excited molecules. The presence of aurorae under some conditions can lead to radar clutter or false targets. It is important to know the state of the aurora and when radar clutter is likely. For this reason, models of the aurora have been developed and used in an operational center for many decades. Recently, a data-driven auroral precipitation model was integrated into the DoD operational center for space weather. The auroral precipitation model is data-driven in a sense that solar wind observations from the Lagrangian point L1 are used to drive a statistical model of Earth’s aurorae to provide nowcasts and short-duration forecasts of auroral activity. The project began with a laboratory-grade prototype and an algorithm theoretical basis document, then through a tailored Agile development process, deployed operational-grade code to a DoD operational center. The Agile development process promotes adaptive planning, evolutionary development, early delivery, continuous improvement, regular collaboration with the customer, and encourages rapid and flexible response to customer-driven changes. The result was an operational capability that met customer expectations for reliability, security, and scientific accuracy. Details of the model and the process of operational integration are discussed as well as lessons learned to improve performance on future projects. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA228660','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA228660">Report on Research for Period January 1983-December 1984</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1985-06-28 WORK UNIT ELEMENT NO. NO. NO. NO 11. TITLE (Include Security Clasification) 9993 XX Report on Research 12. PERSONAL AUTHOR(S) Alice B. McGinty...4rborne Measure- ments -Auroral Soundino Rocket Probes Infrared Atmospnerc Modeling Appendices A AFGL Projects by Program Element 203 B AFGL Rocket Program...obtained a strip map of the earth’s of neutral winds and ionospheric plasma, ionosphere seen from the polar- orbiting electric field-driven plasma drifts, ion </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA11A2244J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA11A2244J">The variations of oxygen emissions in corresponding to Earth's aurora in low latitude region under influence of solar wind dynamics</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jamlongkul, P.; Wannawichian, S. 2017-12-01 Earth's aurora in low latitude region was studied via time variations of oxygen emission spectra, simultaneously with solar wind data. The behavior of spectrum intensity, in corresponding with solar wind condition, could be a trace of aurora in low latitude region including some effects of high energetic auroral particles. Oxygen emission spectral lines were observed by Medium Resolution Echelle Spectrograph (MRES) at 2.4-m diameter telescope at Thai National Observatory, Inthanon Mountain, Chiang Mai, Thailand, during 1-5 LT on 5 and 6 February 2017. The observed spectral lines were calibrated via Dech95 - 2D image processing program and Dech-Fits spectra processing program for spectrum image processing and spectrum wavelength calibration, respectively. The variations of observed intensities each day were compared with solar wind parameters, which are magnitude of IMF (|BIMF|) including IMF in RTN coordinate (BR, BT, BN), ion density (ρ), plasma flow pressure (P), and speed (v). The correlation coefficients between oxygen spectral emissions and different solar wind parameters were found to vary in both positive and negative behaviors. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5282500','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5282500">Global solar wind variations over the last four centuries</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Owens, M. J.; Lockwood, M.; Riley, P. 2017-01-01 The most recent “grand minimum” of solar activity, the Maunder minimum (MM, 1650–1710), is of great interest both for understanding the solar dynamo and providing insight into possible future heliospheric conditions. Here, we use nearly 30 years of output from a data-constrained magnetohydrodynamic model of the solar corona to calibrate heliospheric reconstructions based solely on sunspot observations. Using these empirical relations, we produce the first quantitative estimate of global solar wind variations over the last 400 years. Relative to the modern era, the MM shows a factor 2 reduction in near-Earth heliospheric magnetic field strength and solar wind speed, and up to a factor 4 increase in solar wind Mach number. Thus solar wind energy input into the Earth’s magnetosphere was reduced, resulting in a more Jupiter-like system, in agreement with the dearth of auroral reports from the time. The global heliosphere was both smaller and more symmetric under MM conditions, which has implications for the interpretation of cosmogenic radionuclide data and resulting total solar irradiance estimates during grand minima. PMID:28139769 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSM51A2296B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSM51A2296B">Anticipating Juno Observations of the Magnetosphere of Jupiter</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bunnell, E.; Fowler, C. M.; Bagenal, F.; Bonfond, B. 2012-12-01 The Juno spacecraft will arrive at Jupiter in 2016 and will go into polar orbit. Juno will make the first exploration of the polar regions of Jupiter's vast magnetosphere, combining in situ particles and fields measurements with remote sensing of auroral emissions in the UV, IR and radio. The primary science period comprises ~30 orbits with 11-day periods with a~1.06Rj perijove, allowing Juno to duck under the hazardous synchrotron radiation belts. Apojove is at ~38Rj. The oblateness of the planet causes the orbit to precess with the major axis moving progressively south at about 1 degree per orbit, eventually bringing the spacecraft into the radiation belts. This orbit allows unprecedented views of the aurora and exploration of the auroral acceleration regions. We present an overview of anticipated Juno observations based on models of the Jovian magnetosphere. On approach to Jupiter and over a capture orbit that extends to ~180Rj on the dawn flank, Juno will traverse the magnetosheath, magnetopause and boundary layer regions of the magnetosphere. Due to the high plasma pressures in the magnetospheric plasmasheet the magnetosphere of Jupiter is known to vary substantially with the changes in the solar wind dynamic pressure. We use Ulysses solar wind data obtained around 5 AU to predict the conditions that Juno will observe over the several months it will spend in these boundary regions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19960021212','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19960021212">Evolution of a localized Langmuir packet in the solar wind and on auroral field lines</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Roth, I.; Muschietti, L.; Brown, E. F.; Gray, P. C. 1994-01-01 Langmuir emissions in space are reported to be clumpy and intermittent. The high-frequency wave power appears concentrated in spatial packets, whether amidst the solar wind or on auroral field lines. Due to the plasma motion relative to the spacecraft, determining the source for the wave free energy in the three-dimensional electron distribution function has always been difficult, since the unstable features pass by the detector in presumably too short time to be measured. The range of unstable phase velocities and growth rates have generally been estimated rather than determined by unequivocal measurements. The analysis of wave-particle interactions in a space environment has taken recently a new turn with the development of wave correlators on board rockets and satellites. Such instruments seek to identify correlations between the phase of the wave-field and the fluxes of energetic particles. The data interpretation is complex, however, it must be backed by a detailed theoretical understanding of the wave-particle interaction, including the phase relation for inhomogeneous packets. To this end Langmuir packets interacting with fast electrons can be studied in the appropriate regime by means of particle-in-cell simulations, provided that one succeeds in reducing the level of the fluctuations, enhancing the signal-to-noise ratio, and incorporating the appropriate boundary conditions. The first results of such simulations are presented here as a test and expansion of previous analysis. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA135447','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA135447">Preliminary Results on TID (Travelling Ionospheric Disturbances) over Ebro from TEC Data.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1982-10-30 auroral zone during magnetio substOrms (Chimonas and Etnes,1970, Testud , 1970, Titheridge,1971) while several causes have been poin-ted out for the...88 62 Testud , J.. 1970 Jro.At.Terr.,A202,32087 Mutnri, .. 1971 Jus.GoPhys.esL1,6915 TOkuao,I., .Om andLle195JAmerPhs,715 0. tsui .ad .g 19J73 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990093200&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dconvection%2Bcurrents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990093200&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dconvection%2Bcurrents">POLAR-UVI and other Coordinated Observations of a Traveling Convection Vortex Event Observed on 24 July 1996</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Clauer, C. R.; Baker, J. B.; Ridley, A. J.; Sitar, R. J.; Papitashvili, V. O.; Cumnock, J.; Spann, J. F., Jr.; Brittnacher, M. J.; Parks, G. K. 1997-01-01 Coordinated analysis of data from the POLAR UVI instrument, ground magnetometers, incoherent scatter radar, solar wind monitors IMP-8 and WIND, and DMSP satellite is focused on a traveling convection vortex (TCV) event on 24 July 1966. Starting at 10:48 UT, ground magnetometers in Greenland and eastern Canada measure pulsations consistent with the passing overhead of a series of alternating TCV field-aligned current pairs. Sondrestrom incoherent scatter radar measures strong modulation of the strength and direction of ionospheric plasma flow, The magnetometer pulsations grow in magnitude over the next hour, peaking in intensity at 11:39 UT, at which time the UVI instrument measures a localized intensification of auroral emissions over central and western Greenland. Subsequent images show the intensification grow in strength and propagate westward (tailward) until approximately 11:58 UT at which time the emissions fade. These observations are consistent with the westward passage of two pairs of moderately intense TCVs over central Greenland followed by a third very intense TCV pair. The intensification of auroral emissions at 11:39 UT is associated with the trailing vortex of the third TCV pair, thought to be the result of an upward field-aligned current. Measurements of the solar wind suggest that a pressure change may be responsible for triggering the first two pairs of TCVS, and that a subsequent sudden change in orientation of the IMF may have produced the intensification of the third TCV pair and the associated aurora] brightening. DMSP particle data indicate that the TCVs occur on field lines which map to the boundary plasma sheet or outer edge of the low latitude boundary layer. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.1042L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.1042L">Observation of atomic oxygen O(1S) green-line emission in the summer polar upper mesosphere associated with high-energy (≥30 keV) electron precipitation during high-speed solar wind streams</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lee, Young-Sook; Kwak, Young-Sil; Kim, Kyung-Chan; Solheim, Brian; Lee, Regina; Lee, Jaejin 2017-01-01 The auroral green-line emission at 557.7 nm wavelength as arising from the atomic oxygen O(1S → 1D) transition typically peaks at an altitude of 100 km specifically in the nightside oval, induced by auroral electrons within an energy range of 100 eV-30 keV. Intense aurora is known as being suppressed by sunlight in summer daytime but usually occurs in low electrical background conductivity. However, in the present study in summer (July) sunlit condition, enhancements of O(1S) emission rates observed by using the Wind Imaging Interferometer/UARS were frequently observed at low altitudes below 90 km, where ice particles are created initially as subvisible and detected as polar mesosphere summer echoes, emerging to be an optical phenomenon of polar mesospheric clouds. The intense O(1S) emission occurring in summer exceeds those occurring in the daytime in other seasons both in occurrence and in intensity, frequently accompanied by occurrences of supersonic neutral velocity (300-1500 m s-1). In the mesosphere, ion motion is controlled by electric field and the momentum is transferred to neutrals. The intense O(1S) emission is well associated with high-energy electron precipitation as observed during an event of high-speed solar wind streams. Meanwhile, since the minimum occurrences of O(1S) emission and supersonic velocity are maintained even in the low precipitation flux, the mechanism responsible is not only related to high-energy electron precipitation but also presumably to the local conditions, including the composition of meteoric-charged ice particles and charge separation expected in extremely low temperatures (<150 K). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoRL..41.8713F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoRL..41.8713F">Increases in plasma sheet temperature with solar wind driving during substorm growth phases</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Forsyth, C.; Watt, C. E. J.; Rae, I. J.; Fazakerley, A. N.; Kalmoni, N. M. E.; Freeman, M. P.; Boakes, P. D.; Nakamura, R.; Dandouras, I.; Kistler, L. M.; Jackman, C. M.; Coxon, J. C.; Carr, C. M. 2014-12-01 During substorm growth phases, magnetic reconnection at the magnetopause extracts ~1015 J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4459207','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4459207">Increases in plasma sheet temperature with solar wind driving during substorm growth phases</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Forsyth, C; Watt, C E J; Rae, I J; Fazakerley, A N; Kalmoni, N M E; Freeman, M P; Boakes, P D; Nakamura, R; Dandouras, I; Kistler, L M; Jackman, C M; Coxon, J C; Carr, C M 2014-01-01 During substorm growth phases, magnetic reconnection at the magnetopause extracts ∼1015 J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase. PMID:26074645 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26074645','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26074645">Increases in plasma sheet temperature with solar wind driving during substorm growth phases.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Forsyth, C; Watt, C E J; Rae, I J; Fazakerley, A N; Kalmoni, N M E; Freeman, M P; Boakes, P D; Nakamura, R; Dandouras, I; Kistler, L M; Jackman, C M; Coxon, J C; Carr, C M 2014-12-28 During substorm growth phases, magnetic reconnection at the magnetopause extracts ∼10 15 J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSM31D..01N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSM31D..01N">Auroral Acceleration, Solar Wind Driving, and Substorm Triggering (Invited)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Newell, P. T.; Liou, K. 2010-12-01 We use a data base of 4861 substorms identified by global UV images to investigate the substorm cycle dependence of various types of aurora, and to obtain new results on substorm triggering by external driving. Although all types of aurora increase at substorm onset, broadband (Alfvénic) aurora shows a particular association with substorms, and, especially, substorm onset. While diffuse electron and monoenergetic auroral precipitating power rises by 79% and 90% respectively following an onset, broadband aurora rises by 182%. In the first 10-15 minutes following onset, the power associated with Alfvénic acceleration is comparable to monoenergetic acceleration (also called “inverted-V” events). In general, this is not the case prior to onset, or indeed, during recovery. The rise time of the electron diffuse aurora following onset is much slower, about 50 minutes, and thus presumably extends into recovery. We also re-investigate the issue of solar wind triggering of substorms by considering not just changes in the solar wind prior to onset, but how the pattern of changes differs from random and comparable epochs. We verify that a preonset reduction of solar wind driving (“northward turning” in the simplest case of IMF Bz) holds for the superposed epoch mean of the ensemble. Moreover, this reduction is not the result of a small number of substorms with large changes. The reduction starts about 20 min prior to substorm onset, which, although a longer delay than previously suggested, is appropriate given the various propagation time delays involved. Next, we compare the IMF to random solar wind conditions. Not surprisingly, solar wind driving prior to onset averages somewhat higher than random. Although about a quarter of substorms occur for steady northward IMF conditions, more general coupling functions such as the Kan-Lee electric field, the Borovosky function, or our dΦMP/dt, show very few substorms occur following weak dayside merging. We assembled a data base of solar wind times with slightly elevated conditions, chosen to resemble the integrated driving typical before substorm onsets, but otherwise randomly occuring. We looked at how the IMF subsequently changed after these random elevations, compared to the changes preceding substorms. It turns out that mere reversion to the mean leads to a “northward turning” after the imposed selection criterion end. Thus (slightly generalizing the view of Morley and Freeman), substorms require solar wind driving which produces dayside merging, but external triggering is probably insignificant. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12212274S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12212274S">Flux Enhancements of > 30 keV Electrons at Low Drift Shells L < 1.2 During Last Solar Cycles</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Suvorova, A. V. 2017-12-01 We present results of statistical analysis of enhancements of >30 keV electrons observed by the NOAA/POES satellites during solar cycles 23 and 24 (1998-2016) at low drift shells L < 1.2, so-called forbidden zone. We collected 1,750 days ( 25% of the total time) when fluxes of the forbidden energetic electrons (FEE) exceeded 103 (cm2 s sr)-1. We found 530 days, when FEE fluxes reached high intensity from 104 up to 107 (cm2 s sr)-1. It was found that the FEE enhancements were observed mostly often at the declining phases and solar minimum. More than 85% of the events occurred under fast solar wind (V > 450 km/s), high substorm activity (AL >150 nT), and enhanced interplanetary electric field perturbations (VδB > 1.5 mV/m). The FEE occurrence rate peaks around the local midnight. We have also found a quite unexpected annual variation of the FEE occurrence rate with a pronounced maximum from May to September, a minor peak in December-January, and minima at the equinoxes. The May-September peak, persisting at different solar cycle phases, was assumed to originate from high conductivity in the auroral ionosphere, which is controlled by the dipole tilt angle and provides better conditions for penetration of electric field perturbations into the inner magnetosphere. This allows explanation of the shape and amplitude of annual variation in the FEE occurrence rate from the convolution of the solar wind driver with the penetration conditions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050203851','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050203851">Integrated Modeling Study of the Effects of the Magnetospheric Forcing on the Jovian Ionosphere-Thermosphere System</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bogan, Denis (Technical Monitor); Waite, J. Hunter 2005-01-01 The Jupiter Thermosphere General Circulation Model (JTGCM) calculates the global dynamical structure of Jupiter s thermosphere self-consistently with its global thermal structure and composition. The main heat source that drives the thermospheric flow is high-latitude Joule heating. A secondary source of heating is the auroral process of particle precipitation. Global simulations of Jovian thermospheric dynamics indicate strong neutral outflows from the auroral ovals with velocities up to approx.2 km/s and subsequent convergence and downwelling at the Jovian equator. Such circulation is shown to be an important process for transporting significant amounts of auroral energy t o equatorial latitudes and for regulating the global heat budget in a manner consistent with the high thermospheric temperatures observed by the Galileo probe. Adiabatic compression of the neutral atmosphere resulting from downward motion is an important source of equatorial heating (< 0.06 microbar). The adiabatic heating continues to dominate between 0.06 and 0.2 microbar, but with an addition of comparable heating due to horizontal advection induced by the meridional flow. Thermal conduction plays an important role in transporting heat down to lower altitudes (>0.2microbar) where it is balanced by the cooling associated with the wind transport processes. Interestingly, we find that radiative cooling caused by H3(+), CH4, and C2H2 emissions does not play a significant role in interpreting the Galileo temperature profile. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.658G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.658G">Ultraviolet aurora on outer planets: morphology and remote sensing of electron precipitation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gerard, Jean-Claude; Bisikalo, Dmitry; Shematovich, Valery; Soret, Lauriane 2016-07-01 The aurora is the result of the interaction between energetic particles and the upper atmosphere of a planet. Generally, energetic particles from the magnetosphere penetrate the atmosphere, partly deposit their energy and are partly reflected. Their collisional interactions with the atmospheric atoms and molecules heat the atmosphere and produce auroral emissions. Consequently, the aurora then bears the signature of both the acceleration mechanism and the atmospheric structure and composition. Jupiter's UV auroral H2 and H emissions are generally divided into several components. The main auroral emission at Jupiter is associated with the giant current loop connecting the region of co-rotation breakdown in the middle magnetosphere with the ionosphere. The polar emissions observed inside the main emission are very variable over short timescales. The observed diffuse emission equatorward of the main emission is most likely related to precipitation resulting from wave-particle interactions. Finally, the satellite magnetic footprints are created by accelerated electrons resulting from the interaction between the Galilean moons and the plasma in the Jovian magnetosphere. Saturn's magnetosphere and its aurorae appear to be both solar wind driven as the terrestrial magnetosphere and rotationally dominated, similarly to Jupiter. In addition to the main auroral ring, transient features have been recently identified. Uranus displays aurorae quite different from the other two with faint small-size structures appearing following solar storm activity. These different processes are probably associated with different energy spectra of the precipitated electrons. We present an overview of recent results concerning the relation between morphology, variability and remote sensing of the auroral electron energy in the different components. We show that mapping the UV color ratio is a powerful tool to globally characterize the electron precipitation and the flux-energy relation. Considerable progress is expected with the Cassini Grand Finale and the upcoming Juno mission. The characteristics of the Mars aurora are quite different in the absence of a global magnetic field. Two types of events have been detected. The first one corresponds to localized emissions in the southern hemisphere that are related to the presence of cusp-type structures in the residual magnetic field. Diffuse auroral emission has been observed with MAVEN-IUVS in the northern hemisphere during periods following solar events. Spectral features include the CO Cameron bands, the CO2+ UV doublet, the CO 4th Positive system and the OI multiplets at 130.4 and 135.6 nm. Optical and particle instruments on board Mars Express and MAVEN have simultaneously detected the energetic electrons and their optical auroral signatures. We summarize the characteristics of the discrete aurorae. Monte Carlo simulations of Martian auroral emissions generated by electron fluxes measured in situ with ASPERA-3 will be presented and compared with nadir observations made with the SPICAM instrument. The effects of the presence of the Mars crustal magnetic field on the upward and downward electron fluxes and the emitted power will be discussed and compared with available particle flux data. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-09-10/pdf/2012-22249.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-09-10/pdf/2012-22249.pdf">77 FR 55455 - Approval for Manufacturing Authority Foreign-Trade Zone 72, Brevini Wind USA, Inc., (Wind Turbine...</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a> 2012-09-10 ... Authority Foreign-Trade Zone 72, Brevini Wind USA, Inc., (Wind Turbine Gear Boxes), Yorktown, IN Pursuant to... Wind USA, Inc., within FTZ 72 in Yorktown, Indiana (FTZ Docket 54-2011, filed 8-11-2011); Whereas... procedures within FTZ 72 on behalf of Brevini Wind USA, Inc., as described in the application and Federal... </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active">14</li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active">15</li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSA53A2437L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSA53A2437L">Farley-Buneman Instability Effects on the Ionosphere and Thermosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Liu, J.; Wang, W.; Oppenheim, M. M.; Dimant, Y. S.; Wiltberger, M. J.; Merkin, V. G. 2016-12-01 We have recently implemented a newmodule that includes both the anomalous electron heating and the electron-neutral cooling rate correction associated with the Farley-Buneman Instability (FBI) in the thermosphere-ionosphere electrodynamics global circulation model (TIEGCM). This implementation provides, for the first time, a modeling capability to describe macroscopic effects of the FBI on the ionosphere and thermosphere in the context of a first-principle, self-consistent model. The added heating sources primarily operate between 100 and 130km altitude, and their magnitudes often exceed auroral precipitation heating in the TIEGCM. The induced changes in E region electron temperature in the auroral oval and polar cap by the FBI are remarkable with a maximum Te approaching 2200 K. This is about 4 times larger than the TIEGCM run without FBI heating. Thermosphere wind and composition changes associated with FBI will also be investigated. This investigation demonstrates how researchers can add the important effects of the FBI to magnetosphere-ionosphere-thermosphere models and simulators. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ApJ...858..123H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ApJ...858..123H">Interplanetary Shocks Inducing Magnetospheric Supersubstorms (SML < ‑2500 nT): Unusual Auroral Morphologies and Energy Flow</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hajra, Rajkumar; Tsurutani, Bruce T. 2018-05-01 We present case studies of two interplanetary shock-induced supersubstorms (SSSs) with extremely high intensities (peak SML ‑4418 and ‑2668 nT) and long durations (∼1.7 and ∼3.1 hr). The events occurred on 2005 January 21 and 2010 April 5, respectively. It is shown that these SSSs have a different auroral evolution than a nominal Akasofu-type substorm. The auroras associated with the SSSs did not have the standard midnight onset and following expansion. Instead, at the time of the SML index peak, the midnight sector was generally devoid of intense auroras, while the most intense auroras were located in the premidnight and postmidnight magnetic local times. Precursor energy input through magnetic reconnection was insufficient to balance the large ionospheric energy dissipation during the SSSs. It is argued that besides the release of stored magnetotail energy during the SSSs, these were powered by additional direct driving through both dayside magnetic reconnection and solar wind ram energy. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA554423','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA554423">Development of a Space Flight Prototype Doppler Asymmetric Spatial Heterodyne (DASH) Spectrometer for the Measurement of Upper Atmospheric Winds</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2011-10-31 required for space flight. Dr. John Hughes and Dr. Abas Sivjee of Embry-Riddle Aeronautical University in Daytona FL and all the staff at the HAARP ...Laboratory, was conducted at the High Frequency Active Auroral Research Program ( HAARP ) facility in Alaska. ARROW was shipped to Anchorage AK from...the Naval Research Laboratory in Washington DC and was delivered, installed, and run at the HAARP facility by ARTEP Inc. personnel. The field </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA242698','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA242698">A Comparison of High-Latitude Ionosphere Propagation Predictions from AMBCOM with Measured Data</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1991-03-01 absorption, i.e. auroral absorption and polar cap absorption (PCA), as well as visual displays of aurora borealis . Energetic electrons are the major cause of...Nikhil Dave of the Naval Ocean Systems Center (NOSC), San Diego , California, conducted a comparison of the data produced by two models (RADAR C and AMBCOM...92 vii LIST OF FIGURES Figure 1. The earth’s magnetic field showing the effects of the solar wind ........ 2 Figure 2. The aurora </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA115832','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA115832">TMA Chemical Release Payloads for Stratospheric Wind Measurements Auroral E Program and Related Programs</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1982-03-15 this work was to provide a piston tank filled with trimethyl aluminum for release as a trail in the upper atmosphere. This payload was launched from the...trail payloads. II. PAYLOAD DESCRIPTION The payload consists of a programmer section with plumbing and a piston tank section. The outer shell of the...payload is the wall of the piston tank . The liquid side of the piston tank is filled with 20 pounds of tri- methyl- aluminum (TMA). After filling the </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMSA33A2177F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMSA33A2177F">Preliminary Observations of Ionospheric Response to an Auroral Driver from the MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) Sounding Rocket Campaign</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Fernandes, P. A.; Lynch, K. A.; Hysell, D. L.; Powell, S.; Miceli, R.; Hampton, D. L.; Ahrns, J.; Lessard, M.; Cohen, I. J.; Moen, J. I.; Bekkeng, T. 2012-12-01 The nightside sounding rocket MICA (Magnetosphere-Ionosphere Coupling in the Alfvén Resonator) launched from Poker Flat, AK, on February 19, 2012, and reached an apogee of 325km. MICA was launched into several discrete, localized arcs in the wake of a westward traveling surge. The MICA instrumentation included both in situ and ground based instruments, and was designed to measure the response of the ionosphere to an auroral driver. More specifically, the science goal was to measure response of the ionosphere to a feedback instability in the ionospheric Alfvén resonator. The MICA payload included in situ particle, electric and magnetic field, and GPS instruments. The ground-based array consisted of a multitude of imagers, coherent and incoherent scatter radars, and a Fabry-Perot interferometer. We present observational characteristics of the response of the ionospheric plasma to the auroral drivers inferred from inverting camera data. We compare the measured precipitating electron population to inversions of camera images, which use a transport model to infer a 2D map of the precipitation. Comparisons show that as the payload passes through what appears to be an Alfvénic auroral arc, the in situ electron instrument shows dispersions indicative of Alfvénic activity. We then introduce measurements of the thermal ion distribution, to examine how the auroral arcs drive a response in the ionosphere. The thermal ion data show that the payload potential strengthens as the payload passes through the arc. When including electron density, temperature, and electric field data, we observe times in which the ionospheric environment changes as the precipitation changes, and times during which there is no measured response by the ionosphere. Future work will compare how the ion bulk flow as measured by the thermal ion instrument compares to the ExB drift as measured by the electric field instrument and to the neutral wind measurements from the Fabry-Perot interferometer. Further analysis of the particle data will yield the ion temperature, whose validity we will quantify by comparison to sheath models. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........65H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........65H">Alfven Waves Underlying Ionospheric Destabilization: Ground-Based Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hirsch, Michael During geomagnetic storms, terawatts of power in the million mile-per-hour solar wind pierce the Earth's magnetosphere. Geomagnetic storms and substorms create transverse magnetic waves known as Alfven waves. In the auroral acceleration region, Alfven waves accelerate electrons up to one-tenth the speed of light via wave-particle interactions. These inertial Alfven wave (IAW) accelerated electrons are imbued with sub-100 meter structure perpendicular to geomagnetic field B. The IAW electric field parallel to B accelerates electrons up to about 10 keV along B. The IAW dispersion relation quantifies the precipitating electron striation observed with high-speed cameras as spatiotemporally dynamic fine structured aurora. A network of tightly synchronized tomographic auroral observatories using model based iterative reconstruction (MBIR) techniques were developed in this dissertation. The TRANSCAR electron penetration model creates a basis set of monoenergetic electron beam eigenprofiles of auroral volume emission rate for the given location and ionospheric conditions. Each eigenprofile consists of nearly 200 broadband line spectra modulated by atmospheric attenuation, bandstop filter and imager quantum efficiency. The L-BFGS-B minimization routine combined with sub-pixel registered electron multiplying CCD video stream at order 10 ms cadence yields estimates of electron differential number flux at the top of the ionosphere. Our automatic data curation algorithm reduces one terabyte/camera/day into accurate MBIR-processed estimates of IAW-driven electron precipitation microstructure. This computer vision structured auroral discrimination algorithm was developed using a multiscale dual-camera system observing a 175 km and 14 km swath of sky simultaneously. This collective behavior algorithm exploits the "swarm" behavior of aurora, detectable even as video SNR approaches zero. A modified version of the algorithm is applied to topside ionospheric radar at Mars and broadcast FM passive radar. The fusion of data from coherent radar backscatter and optical data at order 10 ms cadence confirms and further quantifies the relation of strong Langmuir turbulence and streaming plasma upflows in the ionosphere with the finest spatiotemporal auroral dynamics associated with IAW acceleration. The software programs developed in this dissertation solve the century-old problem of automatically discriminating finely structured aurora from other forms and pushes the observational wave-particle science frontiers forward. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AnGeo..28.1167G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AnGeo..28.1167G">Response of the auroral electrojet indices to abrupt southward IMF turnings</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gjerloev, J. W.; Hoffman, R. A.; Ohtani, S.; Weygand, J.; Barnes, R. 2010-05-01 We present results from a study of the behavior of the auroral electrojet indices following abrupt southward turnings of the IMF Bz. The auroral electrojet indices are calculated from observations made by more than 100 ground based stations provided by the SuperMAG collaborators. Based on three simple criteria we selected 73 events. In each event the interval of analysis started at the time of the IMF Bz southward turning and ended 45 minutes later or at the onset of any abrupt energy unloading event in the magnetosphere, regardless of size. We refer to this period as the "pre-unloading phase". To isolate the dependence of the auroral electrojets on the solar induced ionospheric conductivity during this phase we separated the standard AU/AL indices into two new sets of indices defined by the upper and lower envelope of the north-south component for all sunlit stations (AUs/ALs) and for all stations in darkness (AUd/ALd). Based on events and statistical analyses we can conclude that following a southward turning of the IMF Bz the AUd/ALd indices show no measurable response while the AUs/ALs indices clearly intensify. The intensifications of AUs/ALs are dependent on the intensity of the solar wind driver (as measured by IMF Bz or the Akasofu ɛ parameter). The lack of AUd/ALd response does not depend on the intensity of any subsequent substorm. We find that during these isolated events the ionospheric current system is primarily confined to the sunlit ionosphere. This truncated version of the classical global DP-2 current system suggests that auroral electrojet continuity is not maintained across the terminator. Because of its conductivity dependence on the solar zenith angle, this truncated global current pattern is expected to be highly dependent on UT and season and thus can be asymmetric between hemispheres. Thus we argue that the global two-cell DP-2 current system is not a consequence only of a southward turning of the IMF but requires also the reduction of the conductivity gradient at the terminator. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003xmm..pres...31.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003xmm..pres...31.">ESA's Cluster solved an auroral puzzle</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> 2003-05-01 These aurorae - seen as bright spots in Earth’s atmosphere and called ‘dayside proton auroral spots’ - occur when fractures appear in the Earth’s magnetic field, allowing particles given out from the Sun to squirt through and collide with the molecules in our atmosphere. This is the first time that a precise and direct connection between the two events has been made. The Earth’s magnetic field acts like a shield, protecting Earth from the constant stream of tiny particles ejected by the Sun and known as the ‘solar wind’. The solar wind itself is made of hydrogen atoms, broken into their constituent pieces: protons and electrons. When electrons find routes into our atmosphere, they collide with and excite the atoms in the air. When these excited atoms release their energy, it is given out as light, creating the glowing ‘curtains’ we see as the aurora borealis (or the aurora australis in the southern hemisphere). Dayside proton auroral spots are caused by protons ‘stealing’ electrons from the atoms in our atmosphere. On 18 March last year, a jet of energetic solar protons collided with the Earth’s atmosphere and created a bright ‘spot’ seen by NASA’s IMAGE spacecraft, just as Cluster passed overhead and straight through the region where the proton jet was emanating. An extensive analysis of the Cluster results has now shown that the region was experiencing a turbulent event known as ‘magnetic reconnection’. Such a phenomenon takes place when the Earth’s usually impenetrable magnetic field fractures and has to find a new stable configuration. Until the field mends itself, solar protons leak through the gap and jet into Earth’s atmosphere creating the dayside proton aurora. Philippe Escoubet, ESA’s Cluster Project Scientist, comments, “Thanks to Cluster’s observations scientists can directly and firmly link for the first time a dayside proton auroral spot and a magnetic reconnection event.” Tai Phan, leading the investigation at the University of California, Berkeley, United States, now looks forward to a new way of studying the Earth’s protective shield. He says, “This result has opened up a new area of research. We can now watch dayside proton aurorae and use those observations to know where and how the cracks in the magnetic field are formed and how long the cracks remain open. That makes it a powerful tool to study the entry of the solar wind into the Earth’s magnetosphere.” The Earth’s interaction with the Sun is a current focus of scientific attention because of its importance in knowing how the Sun affects the Earth, most notably our climate. Also, while not immediately dangerous to us on Earth, it is also important for quantifying the danger to satellites, which can be damaged or destroyed by powerful solar flares. Note to Editors: Proton aurorae were globally imaged for the first time by NASA’s IMAGE spacecraft. The images revealed the presence of the ‘dayside proton auroral spots’. By a fortunate coincidence, IMAGE and Cluster both spotted the event on 18 March 2002. Combining with IMAGE’s observations, Cluster made it possible to establish the ground truth of the phenomenon. The paper on these results, Simultaneous Cluster and IMAGE Observations of Cusp Reconnection and Auroral Spot for Northward IMF by Tai Phan and 24 other authors will be published in Geophysical Research Letters, 21 May 2003, Vol. 30, No. 10. The principal investigators responsible for the instruments that made these results possible are: Henri Rème of CESR/Toulouse, France (Cluster Proton Detectors), Andre Balogh of Imperial College, London, United Kingdom (Cluster Magnetic Field Instrument) and Stephen Mende of University of California, Berkeley, United States (IMAGE/FUV). More about Cluster ESA’s Cluster is a collection of four spacecraft, launched on two Russian rockets during the summer of 2000. They are now flying in formation around the Earth, relaying the most detailed ever information about how the solar wind affects our planet in 3D. The solar wind is the perpetual stream of subatomic particles given out by the Sun and it can damage communications satellites and power stations on the Earth. The Cluster mission is expected to continue until at least 2005. Cluster is part of the International Living with a Star programme (ILWS), in which space agencies worldwide get together to investigate how variations in the Sun affect the environment of Earth and the other planets. In particular, ILWS concentrate on those aspects of the Sun-Earth system that may affect mankind and society. ILWS is a collaborative initiative between Europe, the United States, Russia, Japan and Canada. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.4860D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.4860D">Solar Wind Energy Input during Prolonged, Intense Northward Interplanetary Magnetic Fields: A New Coupling Function</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Du, A. M.; Tsurutani, B. T.; Sun, W. 2012-04-01 Sudden energy release (ER) events in the midnight sector at auroral zone latitudes during intense (B > 10 nT), long-duration (T > 3 hr), northward (Bz > 0 nT = N) IMF magnetic clouds (MCs) during solar cycle 23 (SC23) have been examined in detail. The MCs with northward-then-southward (NS) IMFs were analyzed separately from MCs with southward-then-northward (SN) configurations. It is found that there is a lack of substorms during the N field intervals of NS clouds. In sharp contrast, ER events do occur during the N field portions of SN MCs. From the above two results it is reasonable to conclude that the latter ER events represent residual energy remaining from the preceding S portions of the SN MCs. We derive a new solar wind-magnetosphere coupling function during northward IMFs: ENIMF = α N-1/12V 7/3B1/2 + β V |Dstmin|. The first term on the right-hand side of the equation represents the energy input via "viscous interaction", and the second term indicates the residual energy stored in the magnetotail. It is empirically found that the magnetosphere/magnetotail can store energy for a maximum of ~ 4 hrs before it has dissipated away. This concept is defining one for ER/substorm energy storage. Our scenario indicates that the rate of solar wind energy injection into the magnetosphere/magnetotail determines the form of energy release into the magnetosphere/ionosphere. This may be more important than the dissipation mechanism itself (in understanding the form of the release). The concept of short-term energy storage is applied for the solar case. It is argued that it may be necessary to identify the rate of energy input into solar magnetic loop systems to be able to predict the occurrence of solar flares. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JASTP.115...41V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JASTP.115...41V">Ionospheric TEC, thermospheric cooling and Σ[O/N2] compositional changes during the 6-17 March 2012 magnetic storm interval (CAWSES II)</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Verkhoglyadova, O. P.; Tsurutani, B. T.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Paxton, L. J. 2014-08-01 A series of four geomagnetic storms (the minimum SYM-H~-148 nT) occurred during the March 6-17, 2012 in the ascending phase of the solar cycle 24. This interval was selected by CAWSES II for its campaign. The GPS total electron content (TEC) database and JPL's Global Ionospheric Maps (GIM) were used to study vertical TEC (VTEC) for different local times and latitude ranges. The largest response to geomagnetic activity is shown in increases of the low-latitude dayside VTEC. Several GPS sites feature post-afternoon VTEC “bite-outs”. During Sudden Impulse (SI+) event on March 8th a peak daytime VTEC restores to about quiet-time values. It is shown that the TIMED/SABER zonal flux of nitric oxide (NO) infrared cooling radiation correlates well with auroral heating. A factor of ~5 cooling increase is noted in some storms. The cooling radiation intensifies in the auroral zone and spreads towards the equator. Effects of the storm appear at lower latitudes ~18.6 h later. The column density ratio Σ[O/N2] is analyzed based on TIMED/GUVI measurements. Both increases (at low latitudes) and decreases (from auroral to middle latitudes) in the ratio occurs during the geomagnetic storms. We suggest that the column density ratio could be enhanced at low to middle latitudes on the dayside partially due to the superfountain effect (atomic oxygen uplift due to ion-neutral drag). It is suggested that decreases in the Σ[O/N2] ratio at high to middle-latitudes may be caused by high thermospheric temperatures. During SI+s, there is an increase in Σ[O/N2] ratio at auroral latitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5264590','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5264590">Unloading Characteristics of Sand-drift in Wind-shallow Areas along Railway and the Effect of Sand Removal by Force of Wind</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Cheng, Jian-jun; Xin, Guo-Wei; Zhi, Ling-yan; Jiang, Fu-qiang 2017-01-01 Wind-shield walls decrease the velocity of wind-drift sand flow in transit. This results in sand accumulating in the wind-shadow zone of both windshield wall and track line, causing severe sand sediment hazard. This study reveals the characteristics of sand accumulation and the laws of wind-blown sand removal in the wind-shadow areas of three different types of windshield walls, utilizing three-dimensional numerical simulations and wind tunnel experiments and on-site sand sediment tests. The results revealed the formation of apparent vortex and acceleration zones on the leeward side of solid windshield walls. For uniform openings, the vortex area moved back and narrowed. When bottom-opening windshield walls were adopted, the track-supporting layer at the step became a conflux acceleration zone, forming a low velocity vortex zone near the track line. At high wind speeds, windshield walls with bottom-openings achieved improved sand dredging. Considering hydrodynamic mechanisms, the flow field structure on the leeward side of different types of windshield structures is a result of convergence and diffusion of fluids caused by an obstacle. This convergence and diffusion effect of air fluid is more apparent at high wind velocities, but not obvious at low wind velocities. PMID:28120915 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JGRA..11610321D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JGRA..11610321D">First observations of the midlatitude evening anomaly using Super Dual Auroral Radar Network (SuperDARN) radars</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> de Larquier, S.; Ruohoniemi, J. M.; Baker, J. B. H.; Ravindran Varrier, N.; Lester, M. 2011-10-01 Under geomagnetically quiet conditions, the daytime midlatitude ionosphere is mainly influenced by solar radiation: typically, electron densities in the ionosphere peak around solar noon. Previous observations from the Millstone Hill incoherent scatter radar (ISR) have evidenced the presence of evening electron densities higher than daytime densities during the summer. The recent development of midlatitude Super Dual Auroral Radar Network (SuperDARN) radars over North America and Japan has revealed an evening enhancement in ground backscatter during the summer. SuperDARN observations are compared to data from the Millstone Hill ISR, confirming a direct relation between the observed evening enhancements in electron densities and ground backscatter. Statistics over a year of data from the Blackstone radar show that the enhancement occurs during sunset for a few hours from April to September. The evening enhancement observed by both SuperDARN and the Millstone Hill ISR is shown to be related to recent satellite observations reporting an enhancement in electron densities over a wide range of longitudes in the Northern Hemisphere midlatitude sector during summer time. Finally, global results from the International Reference Ionosphere (IRI) and the horizontal wind model (HWM07) are presented in relation with previously published experimental results and proposed mechanisms of the evening enhancement, namely, thermospheric horizontal winds and geomagnetic field configuration. It is shown that the IRI captures the features of the evening enhancement as observed by SuperDARN radars and satellites. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770026443','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770026443">Electromagnetic plasma wave emissions from the auroral field lines</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gurnett, D. A. 1977-01-01 The most important types of auroral radio emissions are reviewed, both from a historical perspective as well as considering the latest results. Particular emphasis is placed on four types of electromagnetic emissions which are directly associated with the plasma on the auroral field lines. These emissions are (1) auroral hiss, (2) saucers, (3) ELF noise bands, and (4) auroral kilometric radiation. Ray tracing and radio direction finding measurements indicate that both the auroral hiss and auroral kilometric radiation are generated along the auroral field lines relatively close to the earth, at radial distances from about 2.5 to 5 R sub e. For the auroral hiss the favored mechanism appears to be amplified Cerenkov radiation. For the auroral kilometric radiation several mechanisms have been proposed, usually involving the intermediate generation of electrostatic waves by the precipitating electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38.1487S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38.1487S">Comprehensive Ionospheric Polar and Auroral Observations for Solar Minimum of Cycle 23/24</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sojka, Jan J.; Nicolls, Michael; van Eyken, Anthony; Heinselman, Craig Only the incoherent scatter radar (ISR) is able to simultaneously measure full profiles of elec-tron density, ion temperature, and electron temperatures through the E-and F-layers of the terrestrial ionosphere. Historically ISR's have been operated for periods much less than a month. Hence, their measurements do not constitute a continuous sequence from which quiet, disturbed, and storm periods can reliably be discerned. This is particularly true in the auroral and polar regions. During the International Polar Year (IPY) two ISRs achieved close to 24/7 continuous observations. This presentation describes their data sets and specifically how they can provide the IRI with a fiduciary E-and F-region ionosphere descriptions for solar minimum conditions at auroral and polar cap locations. The ionospheric description being electron den-sity, ion temperature, electron temperature, and even molecular ion composition profiles from as low as 90 km extending several scale heights above the F-layer peak. The auroral location is Poker Flat in Alaska at 65.4° N, 147.5° W where the NSF's new Poker Flat Incoherent Scatter Radar (PFISR) is located. During solar minimum conditions this location is in the auroral region for most of the day and is at mid-latitudes, equatorward of the cusp, for about 4 to 8 hours per day dependent upon geomagnetic activity. In contrast the polar location is Svalbard, at 78° N, 16° E where the EISCAT Svalbard Radar (ESR) is located. For most of the day the ESR is in the Northern Polar Cap often with a noon sector passage through the dayside cusp. Of unique relevance to IRI is that these extended observations have enabled the ionospheric morphology to be demarked between quiet and disturbed. During the IPY year, 1 March 2007 to 29 February 2008, a total of 50 solar wind corotating interaction regions (CIRs) impacted geospace. Each CIR has a one-to-three day geomagnetic disturbance that is observed in the ISR auroral and polar observations. Hence, this data set enables the quiet-background ionosphere to be established as a function of season and local time. This quiet-background ionosphere has the unique attribute that it has self-consistent altitude profiles of the density and the temper-ature. This we believe is a true fiduciary reference for the IRI in a high latitude region, that is otherwise particularly difficult to quantify. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040129631&hterms=fluorescent+probes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dfluorescent%2Bprobes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040129631&hterms=fluorescent+probes&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dfluorescent%2Bprobes">X-ray Probes of Magnetospheric Interactions with Jupiter's Auroral zones, the Galilean Satellites, and the Io Plasma Torus</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Elsner, R. F.; Ramsey, B. D.; Waite, J. H., Jr.; Rehak, P.; Johnson, R. E.; Cooper, J. F.; Swartz, D. A. 2004-01-01 Remote observations with the Chandra X-ray Observatory and the XMM-Newton Observatory have shown that the Jovian system is a source of x-rays with a rich and complicated structure. The planet's polar auroral zones and its disk are powerful sources of x-ray emission. Chandra observations revealed x-ray emission from the Io Plasma Torus and from the Galilean moons Io, Europa, and possibly Ganymede. The emission from these moons is certainly due to bombardment of their surfaces of highly energetic protons, oxygen and sulfur ions from the region near the Torus exciting atoms in their surfaces and leading to fluorescent x-ray emission lines. Although the x-ray emission from the Galilean moons is faint when observed fiom Earth orbit, an imaging x-ray spectrometer in orbit around these moons, operating at 200 eV and above with 150 eV energy resolution, would provide a detailed mapping (down to 40 m spatial resolution) of the elemental composition in their surfaces. Here we describe the physical processes leading to x-ray emission fiom the surfaces of Jupiter's moons and the instrumental properties, as well as energetic ion flux models or measurements, required to map the elemental composition of their surfaces. We discuss the proposed scenarios leading to possible surface compositions. For Europa, the two most extreme are (1) a patina produced by exogenic processes such as meteoroid bombardment and ion implantation, and (2) upwelling of material fiom the subsurface ocean. We also describe the characteristics of X - m , an imaging x-ray spectrometer under going a feasibility study for the JIM0 mission, with the ultimate goal of providing unprecedented x-ray studies of the elemental composition of the surfaces of Jupiter's icy moons and Io, as well as of Jupiter's auroral x-ray emission. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050201918','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050201918">Processes of Equatorial Thermal Structure: An Analysis of Galileo Temperature Profile with 3-D Model</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Majeed, T.; Waite, J. H., Jr.; Bougher, S. W.; Gladstone, G. R. 2005-01-01 The Jupiter Thermosphere General Circulation Model (JTGCM) calculates the global dynamical structure of Jupiter's thermosphere self-consistently with its global thermal structure and composition. The main heat source that drives the thermospheric flow is high-latitude Joule heating. A secondary source of heating is the auroral process of particle precipitation. Global simulations of Jovian thermospheric dynamics indicate strong neutral outflows from the auroral ovals with velocities up to approximately 2 kilometers per second and subsequent convergence and downwelling at the Jovian equator. Such circulation is shown to be an important process for transporting significant amounts of auroral energy to equatorial latitudes and for regulating the global heat budget in a manner consistent with the high thermospheric temperatures observed by the Galileo probe. Adiabatic compression of the neutral atmosphere resulting from downward motion is an important source of equatorial heating (less than 0.06 microbar). The adiabatic heating continues to dominate between 0.06 and 0.2 microbar, but with an addition of comparable heating due to horizontal advection induced by the meridional flow. Thermal conduction plays an important role in transporting heat down to lower altitudes (greater than 0.2microbar) where it is balanced by the cooling associated with the wind transport processes. Interestingly, we find that radiative cooling caused by H3(+), CH4, and C2H2 emissions does not play a significant role in interpreting the Galileo temperature profile. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4750203F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4750203F">Jupiter Climatological Database from Frequent 5-25 µm Mid-IR Spectral Mapping using IRTF/TEXES</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Fletcher, Leigh N.; Orton, Glenn S.; Greathouse, Thomas K.; Sinclair, James; Irwin, Patrick G. J.; Giles, Rohini S.; Encrenaz, Therese; Drossart, Pierre 2015-11-01 We report on the development of a long-term Jovian Climatological Database (JCliD) to explore variability in Jupiter’s atmospheric temperatures, winds, clouds and composition- from long-term seasonal changes to short-term major upheavals. Radiometrically calibrated spectral scan maps of Jupiter have been regularly obtained using the TEXES instrument (Texas Echelon cross Echelle Spectrograph, Lacy et al. 2002, PASP 114, p153-168) between 2012 and 2015. Ten settings between 5 and 25 µm (10-20 cm-1 wide settings at spectral resolutions of 2000-10000) were selected to be sensitive to jovian temperatures (via H2, CH4 and CH3D), tropospheric phosphine and ammonia, tropospheric haze opacity and stratospheric hydrocarbons ethane and acetylene. Diffraction-limited spatial resolutions of 0.6-1.6” were achieved. Observations over consecutive nights allow the creation of full spatial maps for comparison with the visible light record, revealing ephemeral stratospheric wave activity, NEB hotspots, heating at the northern auroral oval, and complex thermal signatures associated with tropospheric vortices, waves and barges. Full spectra are inverted via the NEMESIS retrieval algorithm (Irwin et al., 2008, JSQRT 109, p1136-1150) to map temperatures at multiple altitudes (1-600 mbar), winds, aerosol opacity and gaseous composition. The spatial and spectral resolutions of the resulting maps surpass those obtained during the Cassini flyby of Jupiter in 2000, and permit temporal interpolation to understand the environmental conditions related to the emergence and evolution of discrete features. In December 2014 we find warmer temperatures in the northern stratosphere (a seasonal effect in late northern summer despite Jupiter’s small axial tilt); a hemispheric asymmetry in the tropospheric PH3 distribution due to variations in the vigour of vertical mixing and photolytic shielding; elevated PH3, aerosols and NH3 in the equatorial zone (EZ) related to equatorial uplift; elevated aerosol opacity in the northern and southern tropical zones (NTrZ and STrZ); and enhanced PH3 and aerosols over the Great Red Spot. Maps of retrieved properties will be assembled as a database (JCliD) to aid in the interpretation of Juno data during 2016-2017. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040161447&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DFord','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040161447&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DFord">Simultaneous Chandra X-ray, HST UV, and Ulysses Radio Observations of Jupiter's Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> R. Elsner; Bhardwaj, A.; Waite, H.; Lugaz, N.; Majeed, T.; Cravens, T.; Gladstone, G.; Ford, P.; Grodent, D.; MacDowell, R. 2004-01-01 Observations of Jupiter carried out by the Chandra ACIS-S instrument over 24-26 February, 2003, show that the auroral X-ray spectrum consists of line emission consistent with high-charge states of precipitating ions, and not a continuum as might be expected from remsstrahlung. The part of the spectrum due to oxygen peaks around 650 eV, which indicates a high fraction of fully-stripped oxygen in the precipitating ion flux. The OVIII emission lines at 653 eV and 774 eV, as well as the OVII emission lines at 561 eV and 666 eV, are clearly identified. There is also line emission at lower energies in the spectral region extending from 250 to 350 eV for which sulfur and carbon lines are possible candidates. The Jovian auroral spectra differ significantly from measured cometary X-ray spectra. The charge state distribution of the oxygen ion emission evident in the measured auroral spectra strongly suggests that, independent of the source of the energetic ions (magnetospheric or solar wind) the ions have undergone additional acceleration. For the magnetospheric case, acceleration to energies exceeding 10 MeV is apparently required. The ion acceleration also helps to explain the high intensities of the X-rays observed. The phase space densities of unaccelerated source populations of either solar wind or magnetospheric ions are orders of magnitude too small to explain the observed emissions. The Chandra X-ray observations were executed simultaneously with observations at ultraviolet wavelengths by the Hubble Space Telescope and at radio wavelengths by the Ulysses spacecraft. These additional data sets provide interesting hints as to the location of the source region and the acceleration characteristics of the generation mechanism. The combined observations suggest that the source of the X rays is magnetospheric in origin, and that strong field-aligned electric fields are present which simultaneously create both the several-MeV energetic ion population and the relativistic electrons believed to be responsible for the generation of approximately 40 minute quasi-periodic radio outbursts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E3SWC..1901004B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E3SWC..1901004B">Analysis of wind energy generation possibilities with various rotor types at disadvantageous wind condition zones</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bieniek, Andrzej 2017-10-01 The paper describe possibilities of energy generation using various rotor types but especially with multi-blade wind engine operates in the areas with unfavourable wind condition. The paper presents also wind energy conversion estimation results presented based on proposed solution of multi-blade wind turbine of outer diameter of 4 m. Based on the wind distribution histogram from the disadvantage wind condition zones (city of Basel) and taking into account design and estimated operating indexes of the considered wind engine rotor an annual energy generation was estimated. Also theoretical energy generation using various types of wind turbines operates at disadvantage wind conditions zones were estimated and compared. The conducted analysis shows that introduction of multi-blade wind rotor instead of the most popular 3- blades or vertical axis rotors results of about 5% better energy generation. Simultaneously there are energy production also at very disadvantages wind condition at wind speed lower then 4 m s-1. Based on considered construction of multi-blade wind engine the rise of rotor mounting height from 10 to 30 m results with more then 300 % better results in terms of electric energy generation. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active">15</li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active">16</li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850012142','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850012142">Variation of Derived Mesospheric Nitric Oxide in Relation to Wind and Temperature in Winter</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Friedrich, M.; Torkar, K. M. 1984-01-01 As a good approximation, changes of the NO-density are solely responsible for changes of the non-auroral D-region. Under the assumption that other ion production processes are either known or negligible, one can derive (NO) from electron densities using a suitable effective electron loss rate. In the Winter Anomaly Campaign 1975/76 nineteen rocket payloads carried electron density measurements on fifteen days. On two of these days (NO) was measured in-situ by photometers. For these days one can establish the production not due to Lyman-alpha and NO. This rest production can then be applied to all (NO) derivations based on electron density measurements. In addition, in this campaign winds and temperatures were measured from the ground to approximately the base of the thermosphere. The derived field of NO densities between December 1975 and February 1976 from 70 to 100 km is compared to corresponding fields of winds (zonal and meridional), temperatures, pressure and Richardson numbers. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170004870&hterms=bats&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbats','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170004870&hterms=bats&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbats">The Interplanetary and Magnetospheric Causes of Extreme DB/dt at Equatorial Locations</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Adebesin, Babatunde O.; Pulkkinen, Antti; Ngwira, Chigomezyo M. 2016-01-01 The 1 min resolution solar wind and geomagnetic data obtained from seven equatorial low-latitude stations during four extreme geomagnetic activities are used to investigate the extreme dB/dt perturbations. Simulations of the magnetospheric-ionospheric environment were also performed for varying amplitudes of the solar proton density. Simulations were carried out using the Space Weather Modeling Framework BATS-R-US + RCM model. Both the observations and simulations demonstrated that the appearance time of the extreme dB/dt perturbations at equatorial stations during disturbed conditions is instantaneous and equitable to those experienced at auroral regions yielding time lags of the order of a few seconds. We find that the rapid dB/dt enhancements are caused by the electric field of magnetospheric current origin, which is being enhanced by solar wind density and ram pressure variations and boosted by the equatorial electro jet. Our results indicate that the solar wind proton density variations could be used as a predictor of extreme dB/dt enhancement at equatorial latitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM54A..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM54A..04S">Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System: Modeling Ion Outflow</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Schunk, R. W.; Barakat, A. R.; Eccles, V.; Karimabadi, H.; Omelchenko, Y.; Khazanov, G. V.; Glocer, A.; Kistler, L. M. 2014-12-01 A Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System is being developed in order to provide a rigorous approach to modeling the interaction of hot and cold particle interactions. The framework will include ion and electron kinetic species in the ionosphere, plasmasphere and polar wind, and kinetic ion, super-thermal electron and fluid electron species in the magnetosphere. The framework is ideally suited to modeling ion outflow from the ionosphere and plasmasphere, where a wide range for fluid and kinetic processes are important. These include escaping ion interactions with (1) photoelectrons, (2) cusp/auroral waves, double layers, and field-aligned currents, (3) double layers in the polar cap due to the interaction of cold ionospheric and hot magnetospheric electrons, (4) counter-streaming ions, and (5) electromagnetic wave turbulence. The kinetic ion interactions are particularly strong during geomagnetic storms and substorms. The presentation will provide a brief description of the models involved and discuss the effect that kinetic processes have on the ion outflow. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5890020-thermospheric-response-october-sar-arc-aurora-observed-from-fritz-peak-colorado-calgary-alberta-during-dynamic-explorer-de-noaa-satellite-overflights','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5890020-thermospheric-response-october-sar-arc-aurora-observed-from-fritz-peak-colorado-calgary-alberta-during-dynamic-explorer-de-noaa-satellite-overflights"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hernandez, G.; Meriwether, J.W.; Tepley, C.A. Thermospheric winds and temperatures were observed from Fritz Peak, Colorado and Calgary, Alberta during the 23 October 1981 Stable Auroral Red Arc (SAR-arc) and aurora event. Ground-based photometer observations during the SAR-arc event allowed the position, 630.0 nm emission rate, and width of the SAR-arc over Fritz Peak to be monitored throughout the night. Data from the DE-2 satellite overflight near 0400UT allowed the structure of the SAR-arc near Fritz Peak and the aurora in Canada to be determined. The measurements made from Fritz Peak Observatory during the early evening hours showed a thermospheric response to heating within the SAR-arcmore » with meridional winds flowing away from the region of maximum heating at velocities less than 50 m s/sup -1/. Later during the night the meridional winds measured over Fritz Peak shifted equatorward. The neutral gas temperature decreased from about 1700/sup 0/K in the early evening to about 1200/sup 0/K) before sunrise.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..4311501A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..4311501A">The interplanetary and magnetospheric causes of extreme dB/dt at equatorial locations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Adebesin, Babatunde O.; Pulkkinen, Antti; Ngwira, Chigomezyo M. 2016-11-01 The 1 min resolution solar wind and geomagnetic data obtained from seven equatorial/low-latitude stations during four extreme geomagnetic activities are used to investigate the extreme dB/dt perturbations. Simulations of the magnetospheric-ionospheric environment were also performed for varying amplitudes of the solar proton density. Simulations were carried out using the Space Weather Modeling Framework/BATS-R-US + RCM model. Both the observations and simulations demonstrated that the appearance time of the extreme dB/dt perturbations at equatorial stations during disturbed conditions is instantaneous and equitable to those experienced at auroral regions yielding time lags of the order of a few seconds. We find that the rapid dB/dt enhancements are caused by the electric field of magnetospheric current origin, which is being enhanced by solar wind density and ram pressure variations and boosted by the equatorial electrojet. Our results indicate that the solar wind proton density variations could be used as a predictor of extreme dB/dt enhancement at equatorial latitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.901a2006J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.901a2006J">Time variations of oxygen emission lines and solar wind dynamic parameters in low latitude region</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Jamlongkul, P.; Wannawichian, S.; Mkrtichian, D.; Sawangwit, U.; A-thano, N. 2017-09-01 Aurora phenomenon is an effect of collision between precipitating particles with gyromotion along Earth’s magnetic field and Earth’s ionospheric atoms or molecules. The particles’ precipitation occurs normally around polar regions. However, some auroral particles can reach lower latitude regions when they are highly energetic. A clear emission from Earth’s aurora is mostly from atomic oxygen. Moreover, the sun’s activities can influence the occurrence of the aurora as well. This work studies time variations of oxygen emission lines and solar wind parameters, simultaneously. The emission’s spectral lines were observed by Medium Resolution Echelle Spectrograph (MRES) along with 2.4 meters diameter telescope at Thai National Observatory, Intanon Mountain, Chiang Mai, Thailand. Oxygen (OI) emission lines were calibrated by Dech-Fits spectra processing program and Dech95 2D image processing program. The correlations between oxygen emission lines and solar wind dynamics will be analyzed. This result could be an evidence of the aurora in low latitude region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130013899','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130013899">Space Weather Monitoring for ISS Geomagnetic Storm Studies</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Minow, Joseph I.; Parker, Neergaard 2013-01-01 The International Space Station (ISS) space environments community utilizes near real time space weather data to support a variety of ISS engineering and science activities. The team has operated the Floating Potential Measurement Unit (FPMU) suite of plasma instruments (two Langmuir probes, a floating potential probe, and a plasma impedance probe) on ISS since 2006 to obtain in-situ measurements of plasma density and temperature along the ISS orbit and variations in ISS frame potential due to electrostatic current collection from the plasma environment (spacecraft charging) and inductive (vxB) effects from the vehicle motion across the Earth s magnetic field. An ongoing effort is to use FPMU for measuring the ionospheric response to geomagnetic storms at ISS altitudes and investigate auroral charging of the vehicle as it passes through regions of precipitating auroral electrons. This work is challenged by restrictions on FPMU operations that limit observation time to less than about a third of a year. As a result, FPMU campaigns ranging in length from a few days to a few weeks are typically scheduled weeks in advance for ISS engineering and payload science activities. In order to capture geomagnetic storm data under these terms, we monitor near real time space weather data from NASA, NOAA, and ESA sources to determine solar wind disturbance arrival times at Earth likely to be geoeffective (including coronal mass ejections and high speed streams associated with coronal holes) and activate the FPMU ahead of the storm onset. Using this technique we have successfully captured FPMU data during a number of geomagnetic storm periods including periods with ISS auroral charging. This presentation will describe the strategies and challenges in capturing FPMU data during geomagnetic storms, the near real time space weather resources utilized for monitoring the space weather environment, and provide examples of auroral charging data obtained during storm operations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AnGeo..20.1049M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AnGeo..20.1049M">Investigating the auroral electrojets with low altitude polar orbiting satellites</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Moretto, T.; Olsen, N.; Ritter, P.; Lu, G. 2002-07-01 Three geomagnetic satellite missions currently provide high precision magnetic field measurements from low altitude polar orbiting spacecraft. We demonstrate how these data can be used to determine the intensity and location of the horizontal currents that flow in the ionosphere, predominantly in the auroral electrojets. First, we examine the results during a recent geomagnetic storm. The currents derived from two satellites at different altitudes are in very good agreement, which verifies good stability of the method. Further, a very high degree of correlation (correlation coefficients of 0.8 0.9) is observed between the amplitudes of the derived currents and the commonly used auroral electrojet indices based on magnetic measurements at ground. This points to the potential of defining an auroral activity index based on the satellite observations, which could be useful for space weather monitoring. A specific advantage of the satellite observations over the ground-based magnetic measurements is their coverage of the Southern Hemisphere, as well as the Northern. We utilize this in an investigation of the ionospheric currents observed in both polar regions during a period of unusually steady interplanetary magnetic field with a large negative Y-component. A pronounced asymmetry is found between the currents in the two hemispheres, which indicates real inter-hemispheric differences beyond the mirror-asymmetry between hemispheres that earlier studies have revealed. The method is also applied to another event for which the combined measurements of the three satellites provide a comprehensive view of the current systems. The analysis hereof reveals some surprising results concerning the connection between solar wind driver and the resulting ionospheric currents. Specifically, preconditioning of the magnetosphere (history of the interplanetary magnetic field) is seen to play an important role, and in the winther hemisphere, it seems to be harder to drive currents on the nightside than on the dayside. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990039172&hterms=hydra&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhydra','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990039172&hterms=hydra&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dhydra">Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitation, Plasma Waves, and Convection Observed by Polar</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Hirahara, M.; Horwitz, J. L.; Moore, T. E.; Germany, G. A.; Spann, J. F.; Peterson, W. K.; Shelley, E. G.; Chandler, M. O.; Giles, B. L.; Craven, P. D.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_19990039172'); toggleEditAbsImage('author_19990039172_show'); toggleEditAbsImage('author_19990039172_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_19990039172_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_19990039172_hide"> 1998-01-01 The POLAR satellite often observes upflowing ionospheric ions (UFIs) in and near the aurora] oval on southern perigee (approx. 5000 km altitude) passes. We present the UFI features observed by the thermal ion dynamics experiment (TIDE) and the toroidal imaging mass angle spectrograph (TIMAS) in the dusk-dawn sector under two different geomagnetic activity conditions in order to elicit their relationships with auroral forms, wave emissions, and convection pattern from additional POLAR instruments. During the active interval, the ultraviolet imager (UVI) observed a bright discrete aurora on the duskside after the substorm onset and then observed a small isolated aurora form and diffuse auroras on the dawnside during the recovery phase. The UFIs showed clear conic distributions when the plasma wave instrument (PWI) detected strong broadband wave emissions below approx. 10 kHz, while no significant auroral activities were observed by UVI. At higher latitudes, the low-energy UFI conics gradually changed to the polar wind component with decreasing intensity of the broadband emissions. V-shaped auroral kilometric radiation (AKR) signatures observed above -200 kHz by PWI coincided with the region where the discrete aurora and the UFI beams were detected. The latitude of these features was lower than that of the UFI conics. During the observations of the UFI beams and conics, the lower-frequency fluctuations observed by the electric field instrument were also enhanced, and the convection directions exhibited large fluctuations. It is evident that large electrostatic potential drops produced the precipitating electrons and discrete auroras, the UFI beams, and the AKR, which is also supported by the energetic plasma data from HYDRA. Since the intense broadband emissions were also observed with the UFIs, the ionospheric ions could be energized transversely before or during the parallel acceleration due to the potential drops. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140012682','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140012682">Influence of Persistent Wind Scour on the Surface Mass Balance of Antarctica</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Das, Indrani; Bell, Robin E.; Scambos, Ted A.; Wolovick, Michael; Creyts, Timothy T.; Studinger, Michael; Fearson, Nicholas; Nicolas, Julien P.; Lenaerts, Jan T. M.; vandenBroeke, Michiel R. 2013-01-01 Accurate quantification of surface snow accumulation over Antarctica is a key constraint for estimates of the Antarctic mass balance, as well as climatic interpretations of ice-core records. Over Antarctica, near-surface winds accelerate down relatively steep surface slopes, eroding and sublimating the snow. This wind scour results in numerous localized regions (< or = 200 sq km) with reduced surface accumulation. Estimates of Antarctic surface mass balance rely on sparse point measurements or coarse atmospheric models that do not capture these local processes, and overestimate the net mass input in wind-scour zones. Here we combine airborne radar observations of unconformable stratigraphic layers with lidar-derived surface roughness measurements to identify extensive wind-scour zones over Dome A, in the interior of East Antarctica. The scour zones are persistent because they are controlled by bedrock topography. On the basis of our Dome A observations, we develop an empirical model to predict wind-scour zones across the Antarctic continent and find that these zones are predominantly located in East Antarctica. We estimate that approx. 2.7-6.6% of the surface area of Antarctica has persistent negative net accumulation due to wind scour, which suggests that, across the continent, the snow mass input is overestimated by 11-36.5 Gt /yr in present surface-mass-balance calculations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSA31B2390G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSA31B2390G">Superposed Epoch Studies of the Response of the High-Latitude Magnetosphere-Ionosphere-Thermosphere System to Solar Wind High-Speed Stream Driving</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Grandin, M.; Aikio, A. T.; Kozlovsky, A.; Ulich, T.; Raita, T. 2016-12-01 During the declining phase of the solar cycle, the Earth's magnetosphere-ionosphere-thermosphere system is mainly disturbed by solar wind high-speed streams (HSSs). Their ionospheric response, especially at high latitudes, is not fully understood yet. The perturbations in the ionosphere last for several days. We have examined the effect of HSS in two studies, which apply the superposed epoch method to data to reveal the statistical response in the ionospheric F, E and D regions to such perturbations. We use ionosonde, geomagnetic and cosmic noise absorption data obtained from Finnish stations during 95 high-speed stream events detected between 2006 and 2008. Results show a long-lasting decrease in the F layer critical frequency foF2 between 12 and 23 MLT in summer and equinox. This depletion of the F layer is interpreted as a result of enhanced electric fields inducing ion-neutral frictional heating in the auroral and subauroral regions. The response near noon is different, since foF2 is increased shortly upon arrival of the co-rotating stream interaction region (CIR), possibly because of precipitation of particles from the dayside plasma sheet provoked by the associated solar wind pressure pulse. In the morning sector, both foF2 and foEs show increases for several days, indicating particle precipitation having a soft component. In the study of cosmic noise absorption (CNA), we observe a different response depending on the L-value of the station. Within the auroral oval (L=5-6), CNA gets maximum values in the morning sector 0-12 MLT during the first and second day following the zero epoch. Values are greater during events with longer-lasting high solar wind speed. The CNA maximum shifts to later MLT at lower L values, and in JYV (L=3.8), the maximum takes place at 14 MLT during day 4. Substorm energization events dominate during the first days at 00-01 MLT. We also address the role of Pc5 geomagnetic pulsations observed in association with CNA events. These results may contribute to improve nowcasting and forecasting of space weather activity during high-speed stream events. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011EP%26S...63...47G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011EP%26S...63...47G">Lunar ionosphere exploration method using auroral kilometric radiation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Goto, Yoshitaka; Fujimoto, Takamasa; Kasahara, Yoshiya; Kumamoto, Atsushi; Ono, Takayuki 2011-01-01 The evidence of a lunar ionosphere provided by radio occultation experiments performed by the Soviet spacecraft Luna 19 and 22 has been controversial for the past three decades because the observed large density is difficult to explain theoretically without magnetic shielding from the solar wind. The KAGUYA mission provided an opportunity to investigate the lunar ionosphere with another method. The natural plasma wave receiver (NPW) and waveform capture (WFC) instruments, which are subsystems of the lunar radar sounder (LRS) on board the lunar orbiter KAGUYA, frequently observe auroral kilometric radiation (AKR) propagating from the Earth. The dynamic spectra of the AKR sometimes exhibit a clear interference pattern that is caused by phase differences between direct waves and waves reflected on a lunar surface or a lunar ionosphere if it exists. It was hypothesized that the electron density profiles above the lunar surface could be evaluated by comparing the observed interference pattern with the theoretical interference patterns constructed from the profiles with ray tracing. This method provides a new approach to examining the lunar ionosphere that does not involve the conventional radio occultation technique. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42..688S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42..688S">Intermediate-scale plasma irregularities in the polar ionosphere inferred from GPS radio occultation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shume, E. B.; Komjathy, A.; Langley, R. B.; Verkhoglyadova, O.; Butala, M. D.; Mannucci, A. J. 2015-02-01 We report intermediate-scale plasma irregularities in the polar ionosphere inferred from high-resolution radio occultation (RO) measurements using GPS (Global Positioning System) to CASSIOPE (CAScade Smallsat and IOnospheric Polar Explorer) satellite radio links. The high inclination of CASSIOPE and the high rate of signal reception by the GPS Attitude, Positioning, and Profiling RO receiver on CASSIOPE enable a high-resolution investigation of the dynamics of the polar ionosphere with unprecedented detail. Intermediate-scale, scintillation-producing irregularities, which correspond to 1 to 40 km scales, were inferred by applying multiscale spectral analysis on the RO phase measurements. Using our multiscale spectral analysis approach and satellite data (Polar Operational Environmental Satellites and Defense Meteorological Satellite Program), we discovered that the irregularity scales and phase scintillations have distinct features in the auroral oval and polar cap. We found that large length scales and more intense phase scintillations are prevalent in the auroral oval compared to the polar cap implying that the irregularity scales and phase scintillation characteristics are a function of the solar wind and magnetospheric forcings. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020039730&hterms=activity+Physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dactivity%2BPhysics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020039730&hterms=activity+Physics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dactivity%2BPhysics">Theoretical Technology Research for the International Solar Terrestrial Physics (ISTP) Program</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ashour-Abdalla, Maha; Curtis, Steve (Technical Monitor) 2002-01-01 During the last four years the UCLA (University of California, Los Angeles) IGPP (Institute of Geophysics and Planetary Physics) Space Plasma Simulation Group has continued its theoretical effort to develop a Mission Oriented Theory (MOT) for the International Solar Terrestrial Physics (ISTP) program. This effort has been based on a combination of approaches: analytical theory, large-scale kinetic (LSK) calculations, global magnetohydrodynamic (MHD) simulations and self-consistent plasma kinetic (SCK) simulations. These models have been used to formulate a global interpretation of local measurements made by the ISTP spacecraft. The regions of applications of the MOT cover most of the magnetosphere: solar wind, low- and high- latitude magnetospheric boundary, near-Earth and distant magnetotail, and auroral region. Most recent investigations include: plasma processes in the electron foreshock, response of the magnetospheric cusp, particle entry in the magnetosphere, sources of observed distribution functions in the magnetotail, transport of oxygen ions, self-consistent evolution of the magnetotail, substorm studies, effects of explosive reconnection, and auroral acceleration simulations. A complete list of the activities completed under the grant follow. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720023744','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720023744">Magnetospheric electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Coroniti, F. V.; Thorne, R. M. 1972-01-01 Coupling of source, transport, and sink processes produces a fairly accurate model for the macroscopic structure and dynamics of magnetospheric electrons. Auroral electrons are controlled by convective transport from a plasma sheet source coupled with a precipitation loss due to whistler and electrostatic plasma turbulence. Outer and inner zone electrons are governed by radial diffusion transport from convection and acceleration sources external to the plasmapause and by parasitic precipitation losses arising from cyclotron and Landau interactions with whistler and ion cyclotron turbulence. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSM43A1910S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSM43A1910S">AUGO II: a comprehensive subauroral zone observatory</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Schofield, I. S.; Connors, M. G. 2010-12-01 A new geophysical observatory dedicated to the study of the aurora borealis will be built 25 km southwest of the town of Athabasca, Alberta, Canada. It is anticipated to see first light in the winter of 2010/2011 and be fully operational in the fall of 2011. Based on the highly successful Athabasca University Geophysical Observatory (AUGO), opened in 2002 at the Athabasca University campus in Athabasca, Alberta, AUGO II will have expanded observational capacity featuring up to eight climate-controlled domed optical observation suites for instrumentation, on-site accommodation for up to six researchers, and most importantly, dark skies free of light pollution from urban development. AUGO II will share the same advantages as its predecessor, one being its location in central Alberta, allowing routine study of the subauroral zone, auroral oval studies during active times, and very rarely of the polar cap. Like the original AUGO, AUGO II will be in close proximity to major highways, be connected to a high bandwidth network, and be within two hour driving distance to the city of Edmonton and its international airport. Opportunities are open for guest researchers in space physics to conduct auroral studies at this new, state-of-the-art research facility through the installation of remotely controlled instruments and/or campaigns. An innovative program of instrument development will accompany the new observatory’s enhanced infrastructure with a focus on magnetics and H-beta meridian scanning photometry. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850032969&hterms=Electromagnetic+Spectrum&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DElectromagnetic%2BSpectrum','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850032969&hterms=Electromagnetic+Spectrum&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DElectromagnetic%2BSpectrum">High latitude electromagnetic plasma wave emissions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gurnett, D. A. 1983-01-01 The principal types of electromagnetic plasma wave emission produced in the high latitude auroral regions are reviewed. Three types of radiation are described: auroral kilometric radiation, auroral hiss, and Z mode radiation. Auroral kilometric radiation is a very intense radio emission generated in the free space R-X mode by electrons associated with the formation of discrete auroral arcs in the local evening. Theories suggest that this radiation is an electron cyclotron resonance instability driven by an enhanced loss cone in the auroral acceleration region at altitudes of about 1 to 2 R sub E. Auroral hiss is a somewhat weaker whistler mode emission generated by low energy (100 eV to 10 keV) auroral electrons. The auroral hiss usually has a V shaped frequency time spectrum caused by a freqency dependent beaming of the whistler mode into a conical beam directed upward or downward along the magnetic field. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EOSTr..84..429S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EOSTr..84..429S">Exploring the Secrets of the Aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Siscoe, George Short, professional autobiographies of the founders of space physics have been solicited by AGU's History Committee and published in special sections of Space Physics issues of the Journal of Geophysical Research. Here we have a book-length professional autobiography by the discoverer of magnetospheric substorms, which is arguably the most intensely researched topic in the field.Probably the book's most valuable contribution to the history of space physics is precisely the narration of the discovery of substorms. Exploring the Secrets of the Aurora has an epic quality. It starts with Akasofu's insight that the auroral zone—a circumpolar zone that auroras inhabit, with geographic borders established in the previous century—is a fiction. There followed a struggle to replace it with the concept of an expandable auroral oval, which has quite a different shape. The road to final success entailed Akasofu's installing a chain of aurora-imaging, “all-sky” cameras stretching the north-south length of Alaska. These proved the point and set a precedent for north-south aligned magnetometer chains. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730015701','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730015701">VLF-HISS from electrons in the earth's magnetosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Maeda, K. 1973-01-01 Intensities of auroral and magnetospheric hiss generated by the Cherenkov radiation process of electrons in the lower magnetosphere were calculated with respect to a realistic model of the earth's magnetosphere. In this calculation, the magnetic field was expressed by the Mead-Fairfield Model, and a static model of the iono-magnetospheric plasma distribution was constructed by accumulated data obtained by recent satellite observations. The energy range of hiss producing electrons and the frequency range of produced VLF in the computation are 100 eV to 200 keV, and 2 to 200 kHz, respectively. The maximum hiss intensity produced by soft electrons is more than one order higher than that of hard electron produced hiss. Higher rate of hiss occurrence in the daytime side, particularly in the soft electron precipitation zone in the morning sector, and less association of auroral hiss in nighttime sectors must be, therefore, due to the local time dependence of the energy spectra of precipitating electrons rather than the difference in the geomagnetic field and in the geoplasma distributions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090042811','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090042811">Understanding the X-ray Flaring from Eta Carinae</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moffat, A.F.J.; Corcoran, Michael F. 2009-01-01 We quantify the rapid variations in X-ray brightness ("flares") from the extremely massive colliding wind binary Eta Carinae seen during the past three orbital cycles by RXTE. The observed flares tend to be shorter in duration and more frequent as periastron is approached, although the largest ones tend to be roughly constant in strength at all phases. Plausible scenarios include (1) the largest of multi-scale stochastic wind clumps from the LBV component entering and compressing the hard X-ray emitting wind-wind collision (WWC) zone, (2) large-scale corotating interacting regions in the LBV wind sweeping across the WWC zone, or (3) instabilities intrinsic to the WWC zone. The first one appears to be most consistent with the observations, requiring homologously expanding clumps as they propagate outward in the LBV wind and a turbulence-like powerlaw distribution of clumps, decreasing in number towards larger sizes, as seen in Wolf-Rayet winds. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active">16</li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active">17</li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-06-12/pdf/2012-14275.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-06-12/pdf/2012-14275.pdf">77 FR 34935 - Foreign-Trade Zone 161; Temporary/Interim Manufacturing Authority; Siemens Energy, Inc., (Wind...</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a> 2012-06-12 ... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [Docket T-4-2012] Foreign-Trade Zone 161; Temporary/Interim Manufacturing Authority; Siemens Energy, Inc., (Wind Turbine Nacelles and Hubs); Notice of Approval On April 2, 2012, the Executive Secretary of the Foreign-Trade Zones (FTZ) Board filed an application submitted by the Board of County... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720037561&hterms=geophysique&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgeophysique','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720037561&hterms=geophysique&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgeophysique">Semiannual variations in the neutral composition.</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Mayr, H. G.; Volland, H. 1971-01-01 Meteor trail observations of the meridional mesospheric wind field are analyzed in terms of spherical harmonics, showing a predominance in the P3 term for the semiannual component. This suggests two heat sources for the semiannual variations. One that peaks at the equator is associated with the semiannual migration of the sun between the two hemispheres. A second heat input of greater magnitude that peaks at high latitudes is presumably related to auroral heating associated with the semiannual component in the occurrence of magnetic storms. The wind circulation, consistent with these sources, is shown to cause a semiannual redistribution of the minor constituent O in the lower thermosphere with the effects of decreasing the ratios of O/N2 and O/O2 at high latitudes and of enhancing these ratios at mid to low latitudes during equinox. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004cosp...35.3960S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004cosp...35.3960S">A spectrographic study of the aurora and the relation to solar wind pressure pulses.</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stockton-Chalk, A. B.; Lanchester, B. S.; Ivchenko, N.; Lummerzheim, D.; Throp, K. SIF (Spectrographic Imaging Facility) is a Southampton University / University College London collaboration. The platform consists of a High Throughput Imaging Echelle Spectrograph, HiTIES, two photometers and a narrow angle auroral imager. The spectrograph has a mosaic filter; each of the three spectral panels are centred over/near important spectral features: Hbeta (486.1nm), N2+(470.9nm), N2+(465.2nm), thus allowing studies of proton and electron aurorae. The platform has been successfully deployed in Svalbard since November 1999. The purpose of the experiment was to take spectrographic measurements to study the relationship between proton and electron precipitation and to understand the nature of the precipitating spectrum of protons, both in energy and angular distributions. We present a study of the aurora observed in relation to solar wind pressure pulses. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760027777&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnike','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760027777&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnike">A measurement of perpendicular current density in an aurora</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bering, E. A.; Mozer, F. S. 1975-01-01 A Nike Tomahawk sounding rocket was launched into a 400-gamma auroral substorm from Esrange, Kiruna, Sweden. The rocket instrumentation included a split Langmuir-probe plasma-velocity detector and a double-probe electric-field detector. Above 140-km altitude, the electric field deduced from the ion-flow velocity measurement and the electric field measured by the double probe agree to an accuracy within the uncertainties of the two measurements. The difference between the two measurements at altitudes below 140 km provides an in situ measurement of current density and conductivity. Alternatively, if values for the conductivity are assumed, the neutral-wind velocity can be deduced. The height-integrated current was 0.11 A/m flowing at an azimuth angle of 276 deg. The neutral winds were strong, exhibited substantial altitude variation in the east-west component, and were predominantly southward. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM51E2597M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM51E2597M">Development of the Near-Earth Magnetotail and the Auroral Arc Associated with Substorm Onset: Evidence for a New Model</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Miyashita, Y.; Hiraki, Y.; Angelopoulos, V.; Ieda, A.; Machida, S. 2015-12-01 We have studied the time sequence of the development of the near-Earth magnetotail and the auroral arc associated with a substorm onset, using the data from the THEMIS spacecraft and ground-based observatories at high temporal and spatial resolutions. We discuss four steps of the auroral development, linking them to magnetotail changes: the auroral fading, the initial brightening of an auroral onset arc, the enhancement of the wave-like structure, and the poleward expansion. A case study shows that near-Earth magnetic reconnection began at X~-17 RE at least ~3 min before the auroral initial brightening and ~1 min before the auroral fading. Ionospheric large-scale convection also became enhanced just before the auroral fading and before the auroral initial brightening. Then low-frequency waves were amplified in the plasma sheet at X~-10 RE, with the pressure increase due to the arrival of the earthward flow from the near-Earth reconnection site ~20 s before the enhancement of the auroral wave-like structure. Finally, the dipolarization began ~30 s before the auroral poleward expansion. On the basis of the present observations, we suggest that near-Earth magnetic reconnection plays two roles in the substorm triggering. First, it generates a fast earthward flow and Alfvén waves. When the Alfvén waves which propagate much faster than the fast flow reach the ionosphere, large-scale ionospheric convection is enhanced, leading to the auroral initial brightening and subsequent gradual growth of the auroral wave-like structure. Second, when the reconnection-initiated fast flow reaches the near-Earth magnetotail, it promotes rapid growth of an instability, such as the ballooning instability, and the auroral wave-like structure is further enhanced. When the instability grows sufficiently, the dipolarization and the auroral poleward expansion are initiated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JGRA..107.1127K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JGRA..107.1127K">Simultaneous total electron content and all-sky camera measurements of an auroral arc</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Kintner, P. M.; Kil, H.; Deehr, C.; Schuck, P. 2002-07-01 We present an example of Global Positioning System (GPS) derived total electron content (TEC) and all-sky camera (ASC) images that show increases of TEC by ~10 × 1016 electrons m-2 (10 TEC units) occurring simultaneously with auroral light in ASC images. The TEC example appears to be an E region density enhancement produced by two discrete auroral arcs occurring in the late morning auroral oval at 1000 LT. This suggests that GPS signal TEC measurements can be used to detect individual auroral arcs and that individual discrete auroral arcs are responsible for some high-latitude phase scintillations. The specific auroral feature detected was a poleward moving auroral form believed to occur in the polar cap where the ionosphere is convecting antisunward. The magnitude of the rate of change of TEC (dTEC/dt) is comparable to that previously reported. However, the timescales associated with the event, the order of 1 min, suggest that the data sampling technique commonly used by chain GPS TEC receivers (averaging and time decimation) will undersample E region TEC perturbations produced by active auroral displays. The localized nature of this example implies that L1 ranging errors of at least 1.6 m will be introduced by auroral arcs into systems relying on differential GPS for navigation or augmentation. Although the TEC and auroral arcs presented herein occurred in the late morning auroral oval, we expect that the effects of discrete auroral arcs on GPS TEC and subsequent ranging errors should occur at all local times. Furthermore, GPS receivers can be used to detect individual discrete arcs. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012hst..prop13012L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012hst..prop13012L">Near-equinox spectro-imaging of Uranus aurorae sampling two planetary rotations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lamy, Laurent 2012-10-01 A quarter of century after their discovery by Voyager 2 in 1986, HST sucessfully re-detected Uranus aurorae in 2011 {and also in 1998}, providing the first images of these emissions. Overall, they differ from other well-known planetary aurorae, and their characteristics vary at very different timescales, from minutes to decades. These results have provided the first insights on the poorly known Uranian magnetosphere in 26 years, and opened a rich field of investigation, together with a set of open questions. In addition, while solstice conditions prevailed in 1986, Uranus lay close to equinox in 2011, with the S and N magnetic poles alternately facing the Sun every half a rotation. This unique configuration of an asymmetric magnetosphere, extremely variable over a single rotation, had never been investigated before and deserved to be fully analyzed. New observations of the Uranian aurorae are therefore vital for our understanding of planetary magnetospheres, and HST is the only tool able to remotely investigate these emissions. We thus propose to re-observe Uranus with STIS spectro-imaging at next opposition {29 Sept. 2012} over two planetary rotations, in order to enlarge the set of positive detections and to sample the rotational dynamics of auroral processes and magnetosphere/solar wind interaction. To increase the probability of any possible auroral brightening triggered by magnetospheric compressions, observations will be scheduled in advance during active solar wind conditions at Uranus, near the maximum of solar cycle 24. Additional objectives will include the characterization of the extended neutral corona and the spectral response of atmospheric species. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SpWea..15.1257S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SpWea..15.1257S">Climatology of the Auroral Electrojets Derived From the Along-Track Gradient of Magnetic Field Intensity Measured by POGO, Magsat, CHAMP, and Swarm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Smith, A. R. A.; Beggan, C. D.; Macmillan, S.; Whaler, K. A. 2017-10-01 The auroral electrojets (AEJs) are complex and dynamic horizontal ionospheric electric currents which form ovals around Earth's poles, being controlled by the morphology of the main magnetic field and the energy input from the solar wind interaction with the magnetosphere. The strength and location of the AEJ varies with solar wind conditions and the solar cycle but should also be controlled on decadal timescales by main field secular variation. To determine the AEJ climatology, we use data from four polar Low Earth Orbit magnetic satellite missions: POGO, Magsat, CHAMP, and Swarm. A simple estimation of the AEJ strength and latitude is made from each pass of the satellites, from peaks in the along-track gradient of the magnetic field intensity after subtracting a core and crustal magnetic field model. This measure of the AEJ activity is used to study the response in different sectors of magnetic local time (MLT) during different seasons and directions of the interplanetary magnetic field (IMF). We find a season-dependent hemispherical asymmetry in the AEJ response to IMF By, with a tendency toward stronger (weaker) AEJ currents in the north than the south during By>0 (By<0) around local winter. This effect disappears during local summer when we find a tendency toward stronger currents in the south than the north. The solar cycle modulation of the AEJ and the long-term shifting of its position and strength due to the core field variation are presented as challenges to internal field modeling. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSA13B3987S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSA13B3987S">Intermediate scale plasma density irregularities in the polar ionosphere inferred from radio occultation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shume, E. B.; Komjathy, A.; Langley, R. B.; Verkhoglyadova, O. P.; Butala, M.; Mannucci, A. J. 2014-12-01 In this research, we report intermediate scale plasma density irregularities in the high-latitude ionosphere inferred from high-resolution radio occultation (RO) measurements in the CASSIOPE (CAScade Smallsat and IOnospheric Polar Explorer) - GPS (Global Positioning System) satellites radio link. The high inclination of the CASSIOPE satellite and high rate of signal receptionby the occultation antenna of the GPS Attitude, Positioning and Profiling (GAP) instrument on the Enhanced Polar Outflow Probe platform on CASSIOPE enable a high temporal and spatial resolution investigation of the dynamics of the polar ionosphere, magnetosphere-ionospherecoupling, solar wind effects, etc. with unprecedented details compared to that possible in the past. We have carried out high spatial resolution analysis in altitude and geomagnetic latitude of scintillation-producing plasma density irregularities in the polar ionosphere. Intermediate scale, scintillation-producing plasma density irregularities, which corresponds to 2 to 40 km spatial scales were inferred by applying multi-scale spectral analysis on the RO phase delay measurements. Using our multi-scale spectral analysis approach and Polar Operational Environmental Satellites (POES) and Defense Meteorological Satellite Program (DMSP) observations, we infer that the irregularity scales and phase scintillations have distinct features in the auroral oval and polar cap regions. In specific terms, we found that large length scales and and more intense phase scintillations are prevalent in the auroral oval compared to the polar cap region. Hence, the irregularity scales and phase scintillation characteristics are a function of the solar wind and the magnetospheric forcing. Multi-scale analysis may become a powerful diagnostic tool for characterizing how the ionosphere is dynamically driven by these factors. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3280-306.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3280-306.pdf">24 CFR 3280.306 - Windstorm protection.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a> 2012-04-01 ..., and across the surface of the full roof structure, as uplift loading. For Wind Zones II and III, the... the structure may be used to resist these wind loading effects in all Wind Zones. (1) The provisions... frame structure to be used as the points for connection of diagonal ties, no specific connecting devices... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3280-306.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3280-306.pdf">24 CFR 3280.306 - Windstorm protection.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a> 2013-04-01 ..., and across the surface of the full roof structure, as uplift loading. For Wind Zones II and III, the... the structure may be used to resist these wind loading effects in all Wind Zones. (1) The provisions... frame structure to be used as the points for connection of diagonal ties, no specific connecting devices... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.901a2013H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.901a2013H">Auroral bright spot in Jupiter’s active region in corresponding to solar wind dynamic</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Haewsantati, K.; Wannawichian, S.; Clarke, J. T.; Nichols, J. D. 2017-09-01 Jupiter’s polar emission has brightness whose behavior appears to be unstable. This work focuses on the bright spot in active region which is a section of Jupiter’s polar emission. Images of the aurora were taken by Advanced Camera for Surveys (ACS) onboard the Hubble Space Telescope (HST). Previously, two bright spots, which were found on 13 th May 2007, were suggested to be fixed on locations described by system III longitude. The bright spot’s origin in equatorial plane was proposed to be at distance 80-90 Jovian radii and probably associated with the solar wind properties. This study analyzes additional data on May 2007 to study long-term variation of brightness and locations of bright spots. The newly modified magnetosphere-ionosphere mapping based on VIP4 and VIPAL model is used to locate the origin of bright spot in magnetosphere. Furthermore, the Michigan Solar Wind Model or mSWiM is also used to study the variation of solar wind dynamic pressure during the time of bright spot’s observation. We found that the bright spots appear in similar locations which correspond to similar origins in magnetosphere. In addition, the solar wind dynamic pressure should probably affect the bright spot’s variation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GI......7..113Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GI......7..113Y">A comparative study of auroral morphology distribution between the Northern and Southern Hemisphere based on automatic classification</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yang, Qiuju; Hu, Ze-Jun 2018-03-01 Aurora is a very important geophysical phenomenon in the high latitudes of Arctic and Antarctic regions, and it is important to make a comparative study of the auroral morphology between the two hemispheres. Based on the morphological characteristics of the four labeled dayside discrete auroral types (auroral arc, drapery corona, radial corona and hot-spot aurora) on the 8001 dayside auroral images at the Chinese Arctic Yellow River Station in 2003, and by extracting the local binary pattern (LBP) features and using a k-nearest classifier, this paper performs an automatic classification of the 65 361 auroral images of the Chinese Arctic Yellow River Station during 2004-2009 and the 39 335 auroral images of the South Pole Station between 2003 and 2005. Finally, it obtains the occurrence distribution of the dayside auroral morphology in the Northern and Southern Hemisphere. The statistical results indicate that the four dayside discrete auroral types present a similar occurrence distribution between the two stations. To the best of our knowledge, we are the first to report statistical comparative results of dayside auroral morphology distribution between the Northern and Southern Hemisphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790065606&hterms=RPA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DRPA','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790065606&hterms=RPA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DRPA">Rapid subauroral ion drifts observed by Atmosphere Explorer C</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spiro, R. W.; Heelis, R. A.; Hanson, W. B. 1979-01-01 Results are presented for an investigation of rapid subauroral ion drift features using data obtained over a nearly five-year period from the ion RPA/drift meter on Atmosphere Explorer-C. These latitudinally narrow features are found to be confined predominantly to the local time sector between 18:00 and 02:00 hr. They occur either singly or as multiple events, one of which almost always straddles the equatorward edge of the auroral zone. Their occurrence probability suggests a dependence of magnetic substorm activity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA34A..03V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA34A..03V">Superstorms of November 2003 and 2004: the role of solar wind driving in the ionosphere-thermosphere dynamics</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Verkhoglyadova, O. P.; Komjathy, A.; Mannucci, A. J.; Mlynczak, M. G.; Hunt, L. A.; Paxton, L. J. 2017-12-01 We revisit three complex superstorms of 19-20 November 2003, 7-8 November 2004 and 9-11 November 2004 to analyze ionosphere-thermosphere (IT) effects driven by different solar wind structures. We distinguish structures associated with ICMEs and their upstream sheaths. The efficiencies of the solar wind-magnetosphere connection throughout the storms are estimated by coupling functions. The daytime IT responses to the complex driving are characterized by combining measurements of characteristic IT parameters. We focus on low- and middle-latitude TEC, global thermospheric infrared nitric oxide emission, composition ratio and locations of the auroral boundary obtained from multiple satellite platforms and ground-based measurements (GPS, TIMED/SABER, TIMED/GUVI, DMSP/SSUSI). A variety of metrics are utilized to examine IT phenomena at 1 hour time scales. It is well-known that the November storm periods featured TEC responses that did not fit a typical pattern. The role of direct driving of IT dynamics by solar wind structures and the role of IT pre-conditioning in these storms are examined to explain the complex unusual ionospheric responses. We identify IT feedback effects that can be important for long-lasting strong storms. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870054946&hterms=geophysic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgeophysic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870054946&hterms=geophysic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgeophysic">U.S. national report to the International Union of Geodesy and Geophysics</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gorney, D. J. 1987-01-01 This paper highlights progress by U.S. authors during 1983-1986 in the broad area of auroral research. Atmospheric emissions and their use as a tool for remote-sensing the dynamics, energetics, and effects of auroral activity is a subject which is emphasized here because of the vast progress made in this area on both observational and theoretical fronts. The evolution of primary auroral electrons, the acceleration of auroral ions, small-scale electric fields, auroral kilometric radiation, auroral empirical models and activity indices are also reviewed. An extensive bibliography is supplied. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/6017006-us-national-report-international-union-geodesy-geophysics','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6017006-us-national-report-international-union-geodesy-geophysics">US national report to the International Union of Geodesy and Geophysics</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Gorney, D.J. 1987-04-01 This paper highlights progress by U.S. authors during 1983-1986 in the broad area of auroral research. Atmospheric emissions and their use as a tool for remote-sensing the dynamics, energetics, and effects of auroral activity is a subject which is emphasized here because of the vast progress made in this area on both observational and theoretical fronts. The evolution of primary auroral electrons, the acceleration of auroral ions, small-scale electric fields, auroral kilometric radiation, auroral empirical models and activity indices are also reviewed. An extensive bibliography is supplied. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PASJ...69...86H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PASJ...69...86H">Records of auroral candidates and sunspots in Rikkokushi, chronicles of ancient Japan from early 7th century to 887</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hayakawa, Hisashi; Iwahashi, Kiyomi; Tamazawa, Harufumi; Ebihara, Yusuke; Kawamura, Akito Davis; Isobe, Hiroaki; Namiki, Katsuko; Shibata, Kazunari 2017-12-01 We present the results of the surveys on sunspots and auroral candidates in Rikkokushi, Japanese official histories from the early 7th century to 887, to review the solar and auroral activities. In total, we found one sunspot record and 13 auroral candidates in Rikkokushi. We then examine the records of the sunspots and auroral candidates, compare the auroral candidates with the lunar phase to estimate their reliability, and compare the records of the sunspots and auroral candidates with the contemporary total solar irradiance reconstructed from radioisotope data. We also identify the locations of the observational sites to review possible equatorward expansion of the auroral oval. These discussions suggest a major gap in auroral candidates from the late 7th to early 9th centuries, which includes the candidate of the grand minimum reconstructed from the radioisotope data, a similar tendency as the distributions of sunspot records in contemporary China, and a relatively high magnetic latitude of observational sites with a higher potential for observing aurorae more frequently than at present. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/biblio/5846640-thermospheric-response-october-sar-arc-aurora-observed-from-fritz-peak-colorado-calgary-alberta-during-dynamics-explorer-de-noaa-satellite-overflights','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5846640-thermospheric-response-october-sar-arc-aurora-observed-from-fritz-peak-colorado-calgary-alberta-during-dynamics-explorer-de-noaa-satellite-overflights"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Hernandez, G.; Meriwether, J.W.; Tepley, C.A. Thermospheric winds and temperatures were observed from Fritz Peak, Colorado and Calgary, Alberta during the 23 October 1981 Stable Auroral Red Arc (SAR-arc) and aurora event. Ground-based photometer observations during the SAR-arc event allowed the position, 630.0 nm emission rate, and width of the SAR-arc over Fritz Peak to be monitored throughout the night. Data from the DE-2 satellite overflight near 0400UT allowed the structure of the SAR-arc near Fritz Peak and the aurora in Canada to be determined. The measurements made from Fritz Peak Observatory during the early evening hours showed a thermospheric response to heating within the SAR-arcmore » with meridional winds flowing away from the region of maximum heating at velocities less than 50 m s/sup -1/. Later during the night the meridional winds measured over Fritz Peak shifted equatorward. The neutral gas temperature decreased from about 1700/sup 0/K in the early evening to about 1200/sup 0/K before sunrise. The wind measurements made from Calgary indicated a more complex flow pattern. During the early evening hours the winds were directed poleward, increasing in velocity with latitude from about 50 to 300 m s/sup -1/. Near local midnight the winds reversed to equatorward and also became irregular in the vicinity of the station. The winds in the vicinity of Calgary are under the influence of intense particle precipitation and enhanced ion drag associated with magnetospheric convection that give rise to considerable variability.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA41A2614D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA41A2614D">Southern Hemisphere Upper Thermospheric Wind Climatology</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dhadly, M. S.; Emmert, J. T.; Drob, D. P. 2017-12-01 This study is focused on the poorly understood large-scale upper thermospheric wind dynamics in the southern polar cap, auroral, and mid latitudes. The gaps in our understanding of the dynamic high-latitude thermosphere are largely due to the sparseness of thermospheric wind measurements. Using data from current observational facilities, it is unfeasible to construct a synoptic picture of the Southern Hemisphere upper thermospheric winds. However, enough data with wide spatial and temporal coverage have accumulated to construct a meaningful statistical analysis of winds as function of season, magnetic latitude, and magnetic local time. We use long-term data from nine ground-based stations located at different southern high latitudes and three space-based instruments. These diverse data sets possess different geometries and different spatial and solar coverage. The major challenge of the effort is to combine these disparate sources of data into a coherent picture while overcoming the sampling limitations and biases among the datasets. Our preliminary analyses show mutual biases present among some of them. We first address the biases among various data sets and then combine them in a coherent way to construct maps of neutral winds for various seasons. We then validate the fitted climatology against the observational data and compare with corresponding fits of 25 years of simulated winds from the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model. This study provides critical insight into magnetosphere-ionosphere-thermosphere coupling and sets a necessary benchmark for validating new observations and tuning first-principles models. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active">17</li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active">18</li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RaSc...52..988S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RaSc...52..988S">Distributed sensing of ionospheric irregularities with a GNSS receiver array</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Su, Yang; Datta-Barua, Seebany; Bust, Gary S.; Deshpande, Kshitija B. 2017-08-01 We present analysis methods for studying the structuring and motion of ionospheric irregularities at the subkilometer scale sizes that produce L band scintillations. Spaced-receiver methods are used for Global Navigation Satellite System (GNSS) receivers' phase measurements over approximately subkilometer to kilometer length baselines for the first time. The quantities estimated by these techniques are plasma drift velocity, diffraction anisotropy magnitude and orientation, and characteristic velocity. Uncertainties are quantified by ensemble simulation of noise on the phase signals carried through to the observations of the spaced-receiver linear system. These covariances are then propagated through to uncertainties on drifts through linearization about the estimated values of the state. Five receivers of SAGA, the Scintillation Auroral Global Positioning System (GPS) Array, provide 100 Hz power and phase data for each channel at L1 frequency. The array is sited in the auroral zone at Poker Flat Research Range, Alaska. A case study of a single scintillating satellite observed by the array is used to demonstrate the spaced-receiver and uncertainty estimation process. A second case study estimates drifts as measured by multiple scintillating channels. These scintillations are correlated with auroral activity, based on all-sky camera images. Measurements and uncertainty estimates made over a 30 min period are compared to a collocated incoherent scatter radar and show good agreement in horizontal drift speed and direction during periods of scintillation for which the characteristic velocity is less than the drift velocity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19800064498&hterms=distributed+generation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddistributed%2Bgeneration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19800064498&hterms=distributed+generation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Ddistributed%2Bgeneration">Generation of auroral kilometric radiation and the structure of auroral acceleration region</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Lee, L. C.; Kan, J. R.; Wu, C. S. 1980-01-01 Generation of auroral kilometric radiation (AKR) in the auroral acceleration region is studied. It is shown that auroral kilometric radiation can be generated by backscattered electrons trapped in the acceleration region via a cyclotron maser process. The parallel electric field in the acceleration region is required to be distributed over 1-2 earth radii. The observed AKR frequency spectrum can be used to estimate the altitude range of the auroral acceleration region. The altitudes of the lower and upper boundaries of the acceleration region determined from the AKR data are respectively approximately 2000 and 9000 km. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910026437&hterms=theory+chaos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtheory%2Bchaos','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910026437&hterms=theory+chaos&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dtheory%2Bchaos">Low-dimensional chaos in magnetospheric activity from AE time series</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Vassiliadis, D. V.; Sharma, A. S.; Eastman, T. E.; Papadopoulos, K. 1990-01-01 The magnetospheric response to the solar-wind input, as represented by the time-series measurements of the auroral electrojet (AE) index, has been examined using phase-space reconstruction techniques. The system was found to behave as a low-dimensional chaotic system with a fractal dimension of 3.6 and has Kolmogorov entropy less than 0.2/min. These indicate that the dynamics of the system can be adequately described by four independent variables, and that the corresponding intrinsic time scale is of the order of 5 min. The relevance of the results to magnetospheric modeling is discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://images.nasa.gov/#/details-KSC-07pd0420.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-KSC-07pd0420.html">KSC-07pd0420</a> <a target="_blank" rel="noopener noreferrer" href="https://images.nasa.gov/">NASA Image and Video Library</a> 2007-02-16 KENNEDY SPACE CENTER, FLA. -- At Cape Canaveral Air Force Station, the Delta II rocket with the THEMIS spacecraft atop awaits launch on Pad 17-B. Friday's launch attempt was scrubbed due to upper-level wind violation. The launch window is 6:01 p.m. to 6:19 p.m. EST on Saturday. THEMIS, an acronym for Time History of Events and Macroscale Interactions during Substorms, consists of five identical probes that will track violent, colorful eruptions near the North Pole. This will be the largest number of scientific satellites NASA has ever launched into orbit aboard a single rocket. The THEMIS mission aims to unravel the mystery behind auroral substorms, an avalanche of magnetic energy powered by the solar wind that intensifies the northern and southern lights. The mission will investigate what causes auroras in the Earth’s atmosphere to dramatically change from slowly shimmering waves of light to wildly shifting streaks of bright color. Photo credit: NASA/Kim Shiflett </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100028367','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100028367">Heliophysics 2009 Roadmap and Global Change: Possibilities for Improved Understanding of the Connection</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spann, Jim 2010-01-01 Heliophysics is the science that includes all aspects of the research needed to understand the Sun and its effects on the Earth and the solar system. Six science targets: 1. Origins of Near-Earth Plasma - to understand the origin and transport of terrestrial plasma from its source to the magnetosphere and solar wind. 2. Solar Energetic Particle Acceleration and Transport - to understand how and where solar eruptions accelerate energetic particles that reach Earth. 3. Ion-Neutral Coupling in the Atmosphere - to understand how neutral winds control ionospheric variability. 4. Climate Impacts of Space Radiation - to understand our atmosphere s response to auroral, radiation belt, and solar energetic particles, and the associated effects on nitric oxide (NO) and ozone. 5. Dynamic Geospace Coupling - to understand how magnetospheric dynamics provides energy into the coupled ionosphere-magnetosphere system. 6. Heliospheric Magnetics - to understand the flow and dynamics of transient magnetic structures form the solar interior to Earth. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2134001','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2134001">Weather, host and vector — their interplay in the spread of insect-borne animal virus diseases</a> <a target="_blank" rel="noopener noreferrer" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a> Sellers, R. F. 1980-01-01 The spread of insect-borne animal virus diseases is influenced by a number of factors. Hosts migrate, move or are conveyed over long distances: vectors are carried on the wind for varying distances in search of hosts and breeding sites; weather and climate affect hosts and vectors through temperature, moisture and wind. As parasites of host and vector, viruses are carried by animals, birds and insects, and their spread can be correlated with the migration of hosts and the carriage of vectors on winds associated with the movements of the Intertropical Convergence Zone (ITCZ) and warm winds to the north and south of the limits of the ITCZ. The virus is often transmitted from a local cycle to a migratory cycle and back again. Examples of insect-borne virus diseases and their spread are analysed. Japanese, Murray Valley, Western equine, Eastern equine and St Louis encephalitis represent viruses transmitted by mosquito—bird or pig cycles. The areas experiencing infection with these viruses can be divided into a number of zones: A, B, C, D, E and F. In zone A there is a continuous cycle of virus in host and vector throughout the year; in zone B, there is an upsurge in the cycle during the wet season, but the cycle continues during the dry season; there is movement of infected vectors between and within zones A and B on the ITCZ and the virus is introduced to zone C by infected vectors on warm winds; persistence may occur in zone C if conditions are right. In zone D, virus is introduced each year by infected vectors on warm winds and the arrival of the virus coincides with the presence of susceptible nestling birds and susceptible piglets. The disappearance of virus occurs at the time when migrating mosquitoes and birds are returning to warmer climates. The virus is introduced to zone E only on occasions every 5-10 years when conditions are suitable. Infected hosts introduced to zone F do not lead to circulation of virus, since the climate is unsuitable for vectors. Zones A, B and C correspond to endemic and zones D and E to epidemic conditions. Similar zones can be recognized for African horse sickness, bluetongue, Ibaraki disease and bovine ephemeral fever — examples of diseases transmitted in a midge-mammal cycle. In zones A and B viruses are transported by infected midges carried on the wind in association with the movement of ITCZ and undergo cycles in young animals. In these zones and in zone C there is a continual movement of midges on the warm wind between one area and another, colonizing new sites or reinforcing populations of midges already present. Virus is introduced at times into fringe areas (zones D and E) and, as there is little resistance in the host, gives rise to clinical signs of disease. In some areas there is persistence during adverse conditions; in others, the virus is carried back to the endemic zones by infected midges or vectors. Examples of viruses maintained in a mosquito/biting fly—mammal cycle are Venezuelan equine encephalitis and vesicular stomatitis. These viruses enter a migratory cycle from a local cycle and the vectors in the migratory cycle are carried over long distances on the wind. Further examples of virus spread by movement of vectors include West Nile, Rift Valley fever, yellow fever, epizootic haemorrhagic disease of deer and Akabane viruses. In devising means of control it is essential to decide the relationship of host, vector and virus and the nature of the zone in which the area to be controlled lies. Because of the continual risk of reintroduction of infected vectors, it is preferable to protect the host by dipping, spraying or by vaccination rather than attempting to eliminate the local population of insects. PMID:6131919 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030016695&hterms=FAC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFAC','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030016695&hterms=FAC&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFAC">Ionospheric Convection in the Postnoon Auroral Oval: SuperDARN and Polar UVI Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kozlovsky, A.; Koustov, A.; Lyatsky, W.; Kangas, J.; Parks, G.; Chua, D. 2002-01-01 Super Dual Auroral Radar Network (SuperDARN) observations, ultraviolet imaging from the Polar satellite (UVI), and particle precipitation data from DMSP satellites have been used to investigate the electrodynamics of the postnoon auroral oval in the Northern hemisphere. We show that: (1) For negative IMF By, the convection reversal (CR) was co-located with the maximum of auroral luminosity, but during positive IMF By the convection reversal was poleward of the auroral oval up to several degrees in latitude; (2) Postnoon auroral oval was associated with a large-scale upward field-aligned current (FAC) of the order of 6x10(exp -7). A m(exp -2) in magnitude (the FAC was inferred from the SuperDARN and UVI data). For negative IMF By, maximum of the auroral intensity coincides in latitude with the maximum of the upward field-aligned current. However, for positive IMF By. the maximum of the upward FAC was shifted to the poleward edge of the auroral oval; (3) In response to the IMF By turning from positive to negative, the maximum of the auroral luminosity did not change its position noticeably, but the position of the convection reversal changed considerably from 80-81 degs to about 76 degs MLAT, and the maximum of FAC moved from 77-78 degs to about 76 degs MLAT. Thus, after IMF By turns negative, both the FAC maximum and CR tend to coincide with the auroral maximum; (4) The IMF Bz positive deflection was followed by a decrease in both field-aligned current intensity and auroral luminosity. However, the decrease in the auroral luminosity lags behind the FAC decrease by about 12 min. Firstly, these observations allow us to suggest that the IMF By-related electric field can penetrate into the closed magnetosphere and produce convection and FAC changes in the region of the postnoon auroral oval. Secondly, we suggest that the interchange instability is a promising mechanism for the postnoon auroras. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P11G..06K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P11G..06K">An Ionosphere/Magnetosphere Coupling Current System Located in the Gap Between Saturn and its Rings</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Khurana, K. K.; Dougherty, M. K.; Cao, H.; Hunt, G. J.; Provan, G. 2017-12-01 The Grand Finale Orbits of the Cassini spacecraft traversed through Saturn's D ring and brought the spacecraft to within 3000 km of Saturn's cloud tops. The closest approaches (CA) were near the equatorial plane of Saturn and were distributed narrowly around the local noon. The difference field (observations - internal field - magnetospheric ring current field) obtained from the Grand Finale orbits show persistent residual fields centered around the CA which diminish at higher latitudes on field lines that connect to the ring. Modeling of this perturbation in terms of internal harmonics shows that the perturbation is not of internal origin but is produced by external currents that couple the ionosphere to the magnetosphere. The sense of the current system suggests that the southern feet of the field lines in the ionosphere lead their northern footprints. We show that the observed field perturbations are consistent with a meridional Pedersen current whose strength is 1 MA/radian, i.e. comparable in strength to the Planetary-period-oscillation related current systems observed in the auroral zone. We show that the implied Lorentz force in the ionosphere extracts momentum from the faster moving southern ionosphere and passes it on to the northern ionosphere. We discuss several ideas for generating this current system. In particular, we highlight a mechanism that involves shears in the neutral winds in the thermospheric region to generate the observed magnetic field. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12212111R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12212111R">Dawn Auroral Breakup at Saturn Initiated by Auroral Arcs: UVIS/Cassini Beginning of Grand Finale Phase</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Radioti, A.; Grodent, D.; Yao, Z. H.; Gérard, J.-C.; Badman, S. V.; Pryor, W.; Bonfond, B. 2017-12-01 We present Cassini auroral observations obtained on 11 November 2016 with the Ultraviolet Imaging Spectrograph at the beginning of the F-ring orbits and the Grand Finale phase of the mission. The spacecraft made a close approach to Saturn's southern pole and offered a remarkable view of the dayside and nightside aurora. With this sequence we identify, for the first time, the presence of dusk/midnight arcs, which are azimuthally spread from high to low latitudes, suggesting that their source region extends from the outer to middle/inner magnetosphere. The observed arcs could be auroral manifestations of plasma flows propagating toward the planet from the magnetotail, similar to terrestrial "auroral streamers." During the sequence the dawn auroral region brightens and expands poleward. We suggest that the dawn auroral breakup results from a combination of plasma instability and global-scale magnetic field reconfiguration, which is initiated by plasma flows propagating toward the planet. Alternatively, the dawn auroral enhancement could be triggered by tail magnetic reconnection. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160006717&hterms=jupiter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Djupiter','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160006717&hterms=jupiter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Djupiter">Radio Emission from Red-Giant Hot Jupiters</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Fujii, Yuka; Spiegel, David S.; Mroczkowski, Tony; Nordhaus, Jason; Zimmerman, Neil T.; Parsons, Aaron R.; Mirbabayi, Mehrdad; Madhusudhan, Nikku 2016-01-01 When planet-hosting stars evolve off the main sequence and go through the red-giant branch, the stars become orders of magnitudes more luminous and, at the same time, lose mass at much higher rates than their main sequence counterparts. Accordingly, if planetary companions exist around these stars at orbital distances of a few au, they will be heated up to the level of canonical hot Jupiters and also be subjected to a dense stellar wind. Given that magnetized planets interacting with stellar winds emit radio waves, such "Red-Giant Hot Jupiters" (RGHJs) may also be candidate radio emitters. We estimate the spectral auroral radio intensity of RGHJs based on the empirical relation with the stellar wind as well as a proposed scaling for planetary magnetic fields. RGHJs might be intrinsically as bright as or brighter than canonical hot Jupiters and about 100 times brighter than equivalent objects around main-sequence stars. We examine the capabilities of low-frequency radio observatories to detect this emission and find that the signal from an RGHJ may be detectable at distances up to a few hundred parsecs with the Square Kilometer Array. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM13D4196M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM13D4196M">Relative Timing of Substorm-Associated Processes in the Near-Earth Magnetotail and Development of Auroral Onset Arc</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Miyashita, Y.; Ieda, A.; Machida, S.; Hiraki, Y.; Angelopoulos, V.; McFadden, J. P.; Auster, H. U.; Mende, S. B.; Donovan, E.; Larson, D. E. 2014-12-01 We have studied the relative timing of the processes in the near-Earth magnetotail and development of auroral onset arc at the beginning of the expansion phase, based on substorm events observed by the THEMIS spacecraft and ground-based all-sky imagers. The THEMIS all-sky imagers can observe auroras over a wide area with temporal and spacial resolutions higher than spacecraft-borne cameras. This enables us to investigate the timing of auroral development in more detail than before. A few min after the appearance and intensification of an auroral onset arc, it begins to form wave-like structure. Then auroral poleward expansion begins another few min later. THEMIS magnetotail observations clearly show that magnetic reconnection is initiated at X~-20 Re at least 1-2 min before the intensification of auroral onset arc. Then low-frequency waves are excited in the plasma sheet at X~-10 Re 2 min before dipolarization, which is simultaneous with the formation of auroral wave-like structure. Dipolarization begins at the same time as the auroral poleward expansion. These results suggest that near-Earth magnetic reconnection plays some role in the development of dipolarization and auroral onset arc. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A21E2194M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A21E2194M">Characterisation of recirculation zones in complex terrain using multi-lidar measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Menke, R.; Mann, J.; Vasiljevic, N. 2017-12-01 Wind fields in complex terrain show a higher complexity compared to sites with simpler geometries. It is imperative to understand well the characteristics of complex flows to account for them during the site validation to ensure the wind turbines can withstand the local flow conditions. This study focuses on the description of recirculation zones occurring on lee sides of hills. The flow recirculation can have a significant impact on the success of wind energy projects since it represents one of the main contributors to the turbulence generation. An extensive dataset of observation of flow over complex terrain is available from the Perdigão 2017 field campaign (https://www.nature.com/news/world-s-largest-wind-mapping-project-spins-up-in-portugal-1.21481). A setup of 8 long-range WindScanners (Vasiljević et al., 2016), scanning lidars deployed by DTU performed RHI scans at several positions along two parallel ridges probing the flow field in two vertical planes, in addition data from several meteorological masts is available. With the above-mentioned lidar setup we achieved simultaneous dual-Doppler scans of the recirculation zone at three positions and simultaneous observations of recirculation behind two parallel ridges. Methods are developed to identify and define the extent of recirculation bubbles. Different parameters are defined to characterise the dimensions of the recirculation zone. The change of these parameters along the ridges is studied. In particular, the impact of atmospheric stability and the changes of the wind field at the position of the downwind ridge are investigated. Furthermore, the geometry of the recirculation zone for different wind directions and in connection to the upstream wind conditions is investigated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130003199','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130003199">Space Weather Monitoring for ISS Space Environments Engineering and Crew Auroral Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Minow, Joseph; Pettit, Donald R.; Hartman, William A. 2012-01-01 Today s presentation describes how real time space weather data is used by the International Space Station (ISS) space environments team to obtain data on auroral charging of the ISS vehicle and support ISS crew efforts to obtain auroral images from orbit. Topics covered include: Floating Potential Measurement Unit (FPMU), . Auroral charging of ISS, . Real ]time space weather monitoring resources, . Examples of ISS auroral charging captured from space weather events, . ISS crew observations of aurora. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JGRA..108.8007S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JGRA..108.8007S">Double layers in expanding plasmas and their relevance to the auroral plasma processes</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Singh, Nagendra; Khazanov, George 2003-04-01 When a dense plasma consisting of a cold and a sufficiently warm electron population expands, a rarefaction shock forms [, 1978]. In the expansion of the polar wind in the magnetosphere, it has been previously shown that when a sufficiently warm electron population also exists, in addition to the usual cold ionospheric one, a discontinuity forms in the electrostatic potential distribution along the magnetic field lines [, 1984]. Despite the lack of spatial resolution and the assumption of quasi-neutrality in the polar wind models, such discontinuities have been called double layers (DLs). Recently similar discontinuities have been invoked to partly explain the auroral acceleration of electrons and ions in the upward current region [, 2000]. By means of one-dimensional Vlasov simulations of expanding plasmas, for the first time we make here the connection between (1) the rarefaction shocks, (2) the discontinuities in the potential distributions, and (3) DLs. We show that when plasmas expand from opposite directions into a deep density cavity with a potential drop across it and when the plasma on the high-potential side contains hot and cold electron populations, the temporal evolution of the potential and the plasma distribution generates evolving multiple double layers with an extended density cavity between them. One of the DLs is the rarefaction-shock (RFS) and it forms by the reflections of the cold electrons coming from the high-potential side; it supports a part of the potential drop approximately determined by the hot electron temperature. The other DLs evolve from charge separations arising either from reflection of ions coming from the low-potential side or stemming from plasma instabilities; they support the rest of the potential drop. The instabilities forming these additional double layers involve electron-ion (e-i) Buneman or ion-ion (i-i) two-stream interactions. The electron-electron two-stream interactions on the high-potential side of the RFS generate electron-acoustic waves, which evolve into electron phase-space holes. The ion population originating from the low-potential side and trapped by the RFS is energized by the e-i and i-i instabilities and it eventually precipitates into the high-potential plasma along with an electron beam. Applications of these findings to the auroral plasma physics are discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040000732&hterms=quasi+rest+potential&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dquasi%2Brest%2Bpotential','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040000732&hterms=quasi+rest+potential&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dquasi%2Brest%2Bpotential">Double Layers in Expanding Plasmas and Their Relevance to the Auroral Plasma Processes</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Singh, Nagendra; Khazanov, George 2003-01-01 When a dense plasma consisting of a cold and a sufficiently warm electron population expands, a rarefaction shock forms [Bezzerides et al., 1978]. In the expansion of the polar wind in the magnetosphere, it has been previously shown that when a sufficiently warm electron population also exists, in addition to the usual cold ionospheric one, a discontinuity forms in the electrostatic potential distribution along the magnetic field lines [Barakat and Schunk, 1984]. Despite the lack of spatial resolution and the assumption of quasi-neutrality in the polar wind models, such discontinuities have been called double layers (DLs). Recently similar discontinuities have been invoked to partly explain the auroral acceleration of electrons and ions in the upward current region [Ergun et al., 2000]. By means of one-dimensional Vlasov simulations of expanding plasmas, for the first time we make here the connection between (1) the rarefaction shocks, (2) the discontinuities in the potential distributions, and (3) DLs. We show that when plasmas expand from opposite directions into a deep density cavity with a potential drop across it and when the plasma on the high-potential side contains hot and cold electron populations, the temporal evolution of the potential and the plasma distribution generates evolving multiple double layers with an ,extended density cavity between them. One of the DLs is the rarefaction-shock (RFS) and it forms by the reflections of the cold electrons coming from the high-potential side; it supports a part of the potential drop approximately determined by the hot electron temperature. The other DLs evolve from charge separations arising either from reflection of ions coming from the low-potential side or stemming from plasma instabilities; they support the rest of the potential drop. The instabilities forming these additional double layers involve electron-ion (e-i) Buneman or ion-ion (i-i) two-stream interactions. The electron-electron two-stream interactions on the high-potential side of the RFS generate electron-acoustic waves, which evolve into electron phase-space holes. The ion population originating from the low-potential side and trapped by the RFS is energized by the e-i and i-i instabilities and it eventually precipitates into the high-potential plasma along with an electron beam. Applications of these findings to the auroral plasma physics are discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990102212&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dconvection%2Bcurrents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990102212&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dconvection%2Bcurrents">Multi-Instrument Analysis of a Traveling Convection Vortex Event on July 24, 1996 Coordinated with the Polar UVI</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sitar, R. J.; Clauer, C. R.; Baker, J. B.; Ridley, A. J.; Cumnock, J.; Germany, G. A.; Spann, J. F., Jr.; Brittnacher, M. J.; Parks, G. K. 1998-01-01 We present the analysis of a coordinated set of observations from the POLAR Ultraviolet Imager (UVI), ground magnetometers, incoherent scatter radar, solar wind monitors, DMSP and GOES satellites, focused on a traveling convection vortex (TCV) event on 24th July 1996. Starting at approximately 10:48 UT, around magnetometers in Greenland and northern Canada observe pulsations consistent with the passing overhead of a series of alternating TCV filed-aligned current pairs. Azimuthal scans by the Sondrestrom incoherent scatter radar located near Kangerlussuaq (formerly Sondrestrom), Greenland, at this time show strong modulation in the strength and direction of ionospheric plasma flow. The magnetometer pulsations grow in magnitude over the next hour, peaking in intensity at 11:39 UT, at which time images form the UVI instrument show a localized intensification of auroral emissions over central and western Greenland. Subsequent images show the intensification grow in strength and propagate westward (tailward) until approximately 11:58 UT at which time the intensification fades. These observations are consistent with the westward passage of two pairs of moderately intense TCVs over central Greenland followed by a third very intense TCV pair. The intensification of auroral emissions at 11:39 UT is associated with the trailing vortex of the third TCV pair, thought to be the result of an upward field aligned current. The modulated flow observed by the radar is the result of the strong electric fields associated with the impulsive TCV related field aligned current systems as they pass through the field of view of the radar. Measurements of the solar wind from the V;IND and IMP-8 spacecraft suggest that a pressure change may be responsible for triggering the first two pairs of TCVS, and that a subsequent sudden change in the orientation of the interplanetary magnetic field may have produced the intensification of the third TCV pair and the associated auroral brightening. Magnetometer data from the GOES satellite located over the eastern United States at geostationary orbit is consistent with a series of field-aligned moving tailward past the satellite. DMSP particle data indicated that the TCVs occur on field lines which map to the boundary plasma sheet (BPS). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.5043O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.5043O">Quasi-biennial oscillations in the geomagnetic field: Their global characteristics and origin</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ou, Jiaming; Du, Aimin; Finlay, Christopher C. 2017-05-01 Quasi-biennial oscillations (QBOs), with periods in the range 1-3 years, have been persistently observed in the geomagnetic field. They provide unique information on the mechanisms by which magnetospheric and ionospheric current systems are modulated on interannual timescales and are also of crucial importance in studies of rapid core field variations. In this paper, we document the global characteristics of the geomagnetic QBO, using ground-based data collected by geomagnetic observatories between 1985 and 2010, and reexamine the origin of the signals. Fast Fourier transform analysis of second-order derivatives of the geomagnetic X, Y, and Z components reveals salient QBO signals at periods of 1.3, 1.7, 2.2, 2.9, and 5.0 years, with the most prominent peak at 2.2 years. The signature of geomagnetic QBO is generally stronger in the X and Z components and with larger amplitudes on geomagnetically disturbed days. The amplitude of the QBO in the X component decreases from the equator to the poles, then shows a local maximum at subauroral and auroral zones. The QBO in the Z component enhances from low latitudes toward the polar regions. At high latitudes (poleward of 50°) the geomagnetic QBO exhibits stronger amplitudes during LT 00:00-06:00, depending strongly on the geomagnetic activity level, while at low latitudes the main effect is in the afternoon sector. These results indicate that the QBOs at low-to-middle latitudes and at high latitudes are influenced by different magnetospheric and ionospheric current systems. The characteristics of the multiple peaks in the QBO range are found to display similar latitudinal and local time distributions, suggesting that these oscillations are derived from a common source. The features, including the strong amplitudes seen on disturbed days and during postmidnight sectors, and the results from spherical harmonic analysis, verify that the majority of geomagnetic QBO is of external origin. We furthermore find a very high correlation between the geomagnetic QBO and the QBOs in solar wind speed and solar wind dynamic pressure. This suggests the geomagnetic QBO primarily originates from the current systems due to the solar wind-magnetosphere-ionosphere coupling process. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720010709','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720010709">Auroral oval kinematics program</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Comfort, R. H. 1972-01-01 A computer program which determines the geographic location of the auroral oval for given universal time and level of geomagnetic activity was developed for use on the IBM 7094 computer. The program provides both printed output of geographic coordinates of auroral oval boundaries and polar plots of the auroral oval. In addition, there is available a time-integration option which indicates how long a given location is under the auroral oval during a specified period. A description is given of the program and its use. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780053152&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dconvection%2Bcurrents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780053152&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dconvection%2Bcurrents">Dayside auroral arcs and convection</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Reiff, P. H.; Burch, J. L.; Heelis, R. A. 1978-01-01 Recent Defense Meteorological Satellite Program and International Satellite for Ionospheric Studies dayside auroral observations show two striking features: a lack of visible auroral arcs near noon and occasional fan shaped arcs radiating away from noon on both the morning and afternoon sides of the auroral oval. A simple model which includes these two features is developed by reference to the dayside convection pattern of Heelis et al. (1976). The model may be testable in the near future with simultaneous convection, current and auroral light data. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.625a2008H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.625a2008H">Simulation of wake effects between two wind farms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hansen, K. S.; Réthoré, P.-E.; Palma, J.; Hevia, B. G.; Prospathopoulos, J.; Peña, A.; Ott, S.; Schepers, G.; Palomares, A.; van der Laan, M. P.; Volker, P. 2015-06-01 SCADA data, recorded on the downstream wind farm, has been used to identify flow cases with visible clustering effects. The inflow condition is derived from a partly undisturbed wind turbine, due to lack of mast measurements. The SCADA data analysis concludes that centre of the deficit for the downstream wind farm with disturbed inflow has a distinct visible maximum deficit zone located only 5-10D downstream from the entrance. This zone, representing 20-30% speed reduction, increases and moves downstream for increasing cluster effect and is not visible outside a flow sector of 20-30°. The eight flow models represented in this benchmark include both RANS models, mesoscale models and engineering models. The flow cases, identified according to the wind speed level and inflow sector, have been simulated and validated with the SCADA results. The model validation concludes that all models more or less are able to predict the location and size of the deficit zone inside the downwind wind farm. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active">18</li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active">19</li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AnGeo..35.1249H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AnGeo..35.1249H">Global characteristics of auroral Hall currents derived from the Swarm constellation: dependences on season and IMF orientation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Huang, Tao; Lühr, Hermann; Wang, Hui 2017-11-01 On the basis of field-aligned currents (FACs) and Hall currents derived from high-resolution magnetic field data of the Swarm constellation, the average characteristics of these two current systems in the auroral regions are comprehensively investigated by statistical methods. This is the first study considering both current types determined simultaneously by the same spacecraft in both hemispheres. The FAC distribution, derived from the novel Swarm dual-spacecraft approach, reveals the well-known features of Region 1 (R1) and Region 2 (R2) FACs. At high latitudes, Region 0 (R0) FACs appear on the dayside. Their flow direction, up or down, depends on the orientation of the interplanetary magnetic field (IMF) By component. Of particular interest is the distribution of auroral Hall currents. The prominent auroral electrojets are found to be closely controlled by the solar wind input, but we find no dependence of their intensity on the IMF By orientation. The eastward electrojet is about 1.5 times stronger in local summer than in winter. Conversely, the westward electrojet shows less dependence on season. As to higher latitudes, part of the electrojet current is closed over the polar cap. Here the seasonal variation of conductivity mainly controls the current density. During local summer of the Northern Hemisphere, there is a clear channeling of return currents over the polar cap. For positive (negative) IMF By a dominant eastward (westward) Hall current circuit is formed from the afternoon (morning) electrojet towards the dawn side (dusk side) polar cap return current. The direction of polar cap Hall currents in the noon sector depends directly on the orientation of the IMF By. This is true for both signs of the IMF Bz component. Comparable Hall current distributions can be observed in the Southern Hemisphere but for opposite IMF By signs. Around the midnight sector the westward substorm electrojet is dominating. As expected, it is highly dependent on magnetic activity, but it shows only little response to season and IMF By polarity. An important finding is that all the IMF By dependences of FACs and Hall currents practically disappear in the dark winter hemisphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20120012561&hterms=CAPS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DCAPS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20120012561&hterms=CAPS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DCAPS">24/7 Solar Minimum Polar Cap and Auroral Ion Temperature Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sojka, Jan J.; Nicolls, Michael; van Eyken, Anthony; Heinselman, Craig; Bilitza, Dieter 2011-01-01 During the International Polar Year (IPY) two Incoherent Scatter Radars (ISRs) achieved close to 24/7 continuous observations. This presentation describes their data sets and specifically how they can provide the International Reference Ionosphere (IRI) a fiduciary E- and F-region ionosphere description for solar minimum conditions in both the auroral and polar cap regions. The ionospheric description being electron density, ion temperature and electron temperature profiles from as low as 90 km extending to several scale heights above the F-layer peak. The auroral location is Poker Flat in Alaska at 65.1 N latitude, 212.5 E longitude where the NSF s new Poker Flat Incoherent Scatter Radar (PFISR) is located. This location during solar minimum conditions is in the auroral region for most of the day but is at midlatitudes, equator ward of the cusp, for about 4-8 h per day dependent upon geomagnetic activity. In contrast the polar location is Svalbard, at 78.2 N latitude, 16.0 E longitude where the EISCAT Svalbard Radar (ESR) is located. For most of the day the ESR is in the Northern Polar Cap with a noon sector passage often through the dayside cusp. Of unique relevance to IRI is that these extended observations have enabled the ionospheric morphology to be distinguished between quiet and disturbed geomagnetic conditions. During the IPY year, 1 March 2007 - 29 February 2008, about 50 solar wind Corotating Interaction Regions (CIRs) impacted geospace. Each CIR has a two to five day geomagnetic disturbance that is observed in the ESR and PFISR observations. Hence, this data set also enables the quiet-background ionospheric climatology to be established as a function of season and local time. These two separate climatologies for the ion temperature at an altitude of 300 km are presented and compared with IRI ion temperatures. The IRI ion temperatures are about 200-300 K hotter than the observed values. However, the MSIS neutral temperature at 300 km compares favorably with the quiet-background in temperature, both in magnitude and climatology. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AAS...23145209N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AAS...23145209N">THE RELATIONSHIP BETWEEN THE SEPTEMBER 2017 MARS GLOBAL AURORA EVENT AND CRUSTAL MAGNETIC FIELDS</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Nasr, Camella-Rosa; Schneider, Nick; Connour, Kyle; Jain, Sonal; Deighan, Justin; Jakosky, Bruce; MAVEN/IUVS Team 2018-01-01 In September 2017, the Imaging UltraViolet Spectrograph (IUVS) on the MAVEN spacecraft observed global aurora on Mars caused by a surprisingly strong solar energetic particle event. Widespread “diffuse aurora” have previously been detected on Mars through more limited observations (Schneider et al., Science 350, (2015); DOI: 10.1126/science.aad0313), but recent observations established complete coverage of the observable portion of Mars’ nightside. The aurora was global due to Mars’s lack of a global magnetic field, which allowed energetic electrons from the Sun to directly precipitate into the atmosphere. On September 11th, IUVS detected aurora more than 25 times brighter than any prior IUVS observation, with high SNR detections of aurora at the limb and against the disk of the planet. Fainter auroral emission was seen around the nightside limb over 13 orbits spanning nearly 3 days.On September 14th, during the declining phase of the event, faint linear features and patches were detected by the spacecraft, which were higher than the noise floor, with a similar spatial distribution to “discrete aurora” patches observed on Mars by the SPICAM instrument on the Mars Express spacecraft (Bertaux et al., Nature 435, doi :10.1038/nature03603). Discrete aurora occur near areas of the crust affected by the magnetism left over from Mars’ once-strong dipole field. Emission is limited to regions of the crustal magnetic field where the field lines are likely to be open to solar wind interactions. Those regions are concentrated in Mars’ southern hemisphere centered on 180 degrees east longitude.We studied the localized emissions on 14 September to determine whether there might be a connection between the observed diffuse aurora event and discrete auroral processes. First, we investigated the localized emissions to confirm that the observed signal was consistent with expected auroral spectra. Second, their locations were projected on a map of the crustal magnetic fields to determine if they occurred near open magnetic field lines. We will report on the results of these two studies, and the ramifications for Mars auroral processes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM41A2667B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM41A2667B">Impacts of auroral current systems on ionospheric upflow/outflow</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Burleigh, M.; Zettergren, M. D.; Lynch, K. A.; Lessard, M.; Harrington, M.; Varney, R. H.; Reimer, A. 2017-12-01 The downward current region of an auroral current system often contains large perpendicular DC electric fields. These DC electric fields frictionally heat the local ion population resulting in anisotropic increases in ion temperature that cause large pressure gradients which push the ions outward and upward. These ions may undergo further acceleration from transverse heating by broadband ELF waves and at high altitudes the mirror force can propel ions to escape velocities, resulting in outflow to the magnetosphere. Despite these processes being generally well-known, ion outflow remains difficult to predict due to the myriad of processes acting over a large range of altitudes and physical regimes. The resulting temperature anisotropies, which are known to be able to affect upflow, have an unclear degree of impact in highly variable situations like substorm expansions on the nightside or PMAFs/FTEs on the dayside.In this study we use an anisotropic fluid model, GEMINI-TIA, to examine detailed features of temperature anisotropies and resulting ion downflows/upflows/outflows occurring during the ISINGLASS and RENU2 sounding rocket campaigns. GEMINI-TIA is a 2D ionospheric model is based on a truncated 16-moment description and solves the conservation of mass, momentum, parallel energy, and perpendicular energy for species relevant to the E, F, and topside ionospheric regions. This model encapsulates ionospheric upflow and outflow processes through the inclusion of DC electric fields, and empirical descriptions of heating by soft electron precipitation and BBELF waves. The fluid transport equations are accompanied by an electrostatic current continuity equation to self-consistently describe auroral electric fields. Data used to constrain the model can include perpendicular electric fields, characteristic energy, and total energy flux from incoherent scatter radar, any available neutral density and wind measurements, and precipitating electron fluxes. Results from these constrained simulations are compared against in-situ observations. This allows for the ionospheric temperature anisotropies, which are notoriously difficult to observe, and their impacts on ion upflow response due to auroral drivers to be evaluated by enforcing realistic temporal and spatial dependencies on the drivers. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991IJRSP..20...82R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991IJRSP..20...82R">Winds in the meteor zone over Trivandrum</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Reddi, C. R.; Rajeev, K.; Ramakumar, Geetha 1991-04-01 The height profiles of the zonal and meridional wind obtained from the meteor wind radar data recorded at Trivandrum (8 deg 36 min N, 77 deg E) are presented. Large wind shears were found to exist in the meteor zone over Trivandrum. The profiles showed quasi-sinusoidal variations with altitude and vertical wavelength of the oscillation in the range 15-25 km. Further, there was a large day-to-day variability in the profiles obtained for the same local time on consecutive days. The results are discussed in the light of the winds due to tides and equatorial waves in the low latitudes. The implications of the large wind shears with reference to the local wind effects on the equatorial electrojet are outlined. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..122.7130H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..122.7130H">Associating ground magnetometer observations with current or voltage generators</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hartinger, M. D.; Xu, Z.; Clauer, C. R.; Yu, Y.; Weimer, D. R.; Kim, H.; Pilipenko, V.; Welling, D. T.; Behlke, R.; Willer, A. N. 2017-07-01 A circuit analogy for magnetosphere-ionosphere current systems has two extremes for drivers of ionospheric currents: ionospheric electric fields/voltages constant while current/conductivity vary—the "voltage generator"—and current constant while electric field/conductivity vary—the "current generator." Statistical studies of ground magnetometer observations associated with dayside Transient High Latitude Current Systems (THLCS) driven by similar mechanisms find contradictory results using this paradigm: some studies associate THLCS with voltage generators, others with current generators. We argue that most of this contradiction arises from two assumptions used to interpret ground magnetometer observations: (1) measurements made at fixed position relative to the THLCS field-aligned current and (2) negligible auroral precipitation contributions to ionospheric conductivity. We use observations and simulations to illustrate how these two assumptions substantially alter expectations for magnetic perturbations associated with either a current or a voltage generator. Our results demonstrate that before interpreting ground magnetometer observations of THLCS in the context of current/voltage generators, the location of a ground magnetometer station relative to the THLCS field-aligned current and the location of any auroral zone conductivity enhancements need to be taken into account. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810004173','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810004173">A global model of the neutral thermosphere in magnetic coordinates based on AE-C data</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Stehle, C. G. 1980-01-01 An empirical model of the global atomic oxygen and helium distributions in the thermosphere is developed in a magnetic coordinate system and compared to similar models which are expanded in geographic coordinates. The advantage of using magnetic coordinates is that fewer terms are needed to make predictions which are nearly identical to those which would be obtained from a geographic model with longitudinal and universal time corrections. Magnetic coordinates are more directly related to the major energy inputs in the polar regions than geographic coordinates and are more convenient to use in studies of high latitude energy deposition processes. This is important for comparison with theoretical models where the number of coordinates is limited. The effect of magnetic activity on the atomic oxygen distribution in the morning sector of the high latitude thermosphere in the auroral zone is also considered. A magnetic activity indicator (ML) based on an auroral electrojet index (AL) and the 3 hour ap index are used to relate the atomic oxygen density variations to magnetic activity in this region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950029532&hterms=geocentric+solar+system&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgeocentric%2Bsolar%2Bsystem','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950029532&hterms=geocentric+solar+system&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgeocentric%2Bsolar%2Bsystem">Energy density of ionospheric and solar wind origin ions in the near-Earth magnetotail during substorms</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Daglis, Loannis A.; Livi, Stefano; Sarris, Emmanuel T.; Wilken, Berend 1994-01-01 Comprehensive energy density studies provide an important measure of the participation of various sources in energization processes and have been relatively rare in the literature. We present a statistical study of the energy density of the near-Earth magnetotail major ions (H(+), O(+), He(++), He(+)) during substorm expansion phase and discuss its implications for the solar wind/magnetosphere/ionosphere coupling. Our aim is to examine the relation between auroral activity and the particle energization during substorms through the correlation between the AE indices and the energy density of the major magnetospheric ions. The data we used here were collected by the charge-energy-mass (CHEM) spectrometer on board the Active Magnetospheric Particle Trace Explorer (AMPTE)/Charge Composition Explorer (CCE) satellite in the near-equatorial nightside magnetosphere, at geocentric distances approximately 7 to 9 R(sub E). CHEM provided the opportunity to conduct the first statistical study of energy density in the near-Earth magnetotail with multispecies particle data extending into the higher energy range (greater than or equal to 20 keV/E). the use of 1-min AE indices in this study should be emphasized, as the use (in previous statistical studies) of the (3-hour) Kp index or of long-time averages of AE indices essentially smoothed out all the information on substorms. Most distinct feature of our study is the excellent correlation of O(+) energy density with the AE index, in contrast with the remarkably poor He(++) energy density - AE index correlation. Furthermore, we examined the relation of the ion energy density to the electrojet activity during substorm growth phase. The O(+) energy density is strongly correlated with the pre-onset AU index, that is the eastward electrojet intensity, which represents the growth phase current system. Our investigation shows that the near-Earth magnetotail is increasingly fed with energetic ionospheric ions during periods of enhanced dissipation of auroral currents. The participation of the ionosphere in the substorm energization processes seems to be closely, although not solely, associated with the solar wind/magnetosphere coupling. That is, the ionosphere influences actively the substorm energization processes by responding to the increased solar wind/magnetosphere coupling as well as to the unloading dissipation of stored energy, with the increased feeding of new material into the magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20100024507&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSolar%2Bstill','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20100024507&hterms=Solar+still&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSolar%2Bstill">Solar Wind Ablation of Terrestrial Planet Atmospheres</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moore, Thomas Earle; Fok, Mei-Ching H.; Delcourt, Dominique C. 2009-01-01 Internal plasma sources usually arise in planetary magnetospheres as a product of stellar ablation processes. With the ignition of a new star and the onset of its ultraviolet and stellar wind emissions, much of the volatiles in the stellar system undergo a phase transition from gas to plasma. Condensation and accretion into a disk is replaced by radiation and stellar wind ablation of volatile materials from the system- Planets or smaller bodies that harbor intrinsic magnetic fields develop an apparent shield against direct stellar wind impact, but UV radiation still ionizes their gas phases, and the resulting internal plasmas serve to conduct currents to and from the central body along reconnected magnetic field linkages. Photoionization and thermalization of electrons warms the ionospheric topside, enhancing Jeans' escape of super-thermal particles, with ambipolar diffusion and acceleration. Moreover, observations and simulations of auroral processes at Earth indicate that solar wind energy dissipation is concentrated by the geomagnetic field by a factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Thus internal plasmas enable coupling with the plasma, neutral gas and by extension, the entire body. The stellar wind is locally loaded and slowed to develop the required power. The internal source plasma is accelerated and heated, inflating the magnetosphere as it seeks escape, and is ultimately blown away in the stellar wind. Bodies with little sensible atmosphere may still produce an exosphere of sputtered matter when exposed to direct solar wind impact. Bodies with a magnetosphere and internal sources of plasma interact more strongly with the stellar wind owing to the magnetic linkage between the two created by reconnection. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830027272','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830027272">Modelling of auroral electrodynamical processes: Magnetosphere to mesosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chiu, Y. T.; Gorney, D. J.; Kishi, A. M.; Newman, A. L.; Schulz, M.; Walterscheid, R. L.; CORNWALL; Prasad, S. S. 1982-01-01 Research conducted on auroral electrodynamic coupling between the magnetosphere and ionosphere-atmosphere in support of the development of a global scale kinetic plasma theory is reviewed. Topics covered include electric potential structure in the evening sector; morning and dayside auroras; auroral plasma formation; electrodynamic coupling with the thermosphere; and auroral electron interaction with the atmosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4731113S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4731113S">Jupiter's auroral-related thermal infrared emission from IRTF-TEXES</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sinclair, James; Orton, Glenn; Greathouse, Thomas; Fletcher, Leigh; Irwin, Patrick 2015-11-01 Auroral processes on Jupiter can be observed at a large range of wavelengths. Charged particles of the solar wind are deflected by Jupiter’s magnetic field and penetrate the atmosphere at high latitudes. This results in ion and/or electron precipitation, which produces emission at X-ray, UV, visible, near-infrared and even radio wavelengths. These observations indicate three distinct features of the aurora: 1) filament-like oval structures fixed at the magnetic poles (~80°W (System III) in the south, ~180°W in the north), 2) spatially-continuous but transient aurora that fill these oval regions and 3) discrete spots associated with the magnetic footprints of Io and other Galilean satellites. However, observations in the thermal infrared indicate the aurora also modify the neutral atmosphere. Enhanced emission of CH4 is observed coincident with the auroral ovals and indicates heightened stratospheric temperatures possibly as a result of joule heating by the influx of charged particles. Stronger emission is also observed of C2H2, C2H4, C2H6 and even C6H6 though previous work has struggled to determine whether this is a temperature or compositional effect. In order to quantify the auroral effects on the neutral atmosphere and to support the 2016 Juno mission (which has no thermal infrared instrument) we have performed a retrieval analysis of IRTF-TEXES (Texas Echelon Cross Echelle Spectrograph, 5- to 25-μm) spectra obtained on Dec 11th 2014 near solar maximum. The instrument slit was scanned east-west across high latitudes in each hemisphere and Jupiter’s rotation was used to obtain ~360° longitudinal coverage. Spectra of H2 S(1), CH4, C2H2, C2H4 and C2H6 emission were measured at a resolving power of R = 85000, allowing a large vertical range in the atmosphere (100 - 0.001 mbar) to be sounded. Preliminary retrievals of the vertical temperature profile from H2 S(1) and CH4 measurements at 60°N, 180°W (on aurora), in comparison to 60°N, 60°W (quiescent) indicate the majority of auroral heating occurs from 10- to 1-μbar. We plan on further testing the temperature retrievals and adopting these results in the subsequent retrievals of C2H2, C2H4 and C2H6 to determine compositional contrasts. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P24A..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P24A..08S">High spatial and spectral resolution measurements of Jupiter's auroral regions using Gemini-North-TEXES</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Lacy, J.; Giles, R.; Fletcher, L. N.; Vogt, M.; Irwin, P. G. 2017-12-01 Jupiter exhibits auroral emission at a multitude of wavelengths. Auroral emission at X-ray, ultraviolet and near-infrared wavelengths demonstrate the precipitation of ion and electrons in Jupiter's upper atmosphere, at altitudes exceeding 250 km above the 1-bar level. Enhanced mid-infrared emission of CH4, C2H2, C2H4 and further hydrocarbons is also observed coincident with Jupiter's auroral regions. Retrieval analyses of infrared spectra from IRTF-TEXES (Texas Echelon Cross Echelle Spectrograph on NASA's Infrared Telescope Facility) indicate strong heating at the 1-mbar level and evidence of ion-neutral chemistry, which enriches the abundances of unsaturated hydrocarbons (Sinclair et al., 2017b, doi:10.1002/2017GL073529, Sinclair et al., 2017c (under review)). The extent to which these phenomena in the stratosphere are correlated and coupled physically with the shorter-wavelength auroral emission originating from higher altitudes has been a challenge due to the limited spatial resolution available on the IRTF. Smaller-scale features observed in the near-infrared and ultraviolet emission, such as the main `oval', transient `swirls' and dusk-active regions within the main oval (e.g. Stallard et al., 2014, doi:10.1016/j/Icarus.2015.12.044, Nichols et al., 2017, doi: 10.1002/2017GL073029) are potentially being blurred in the mid-infrared by the diffraction-limited resolution (0.7") of IRTF's 3-metre primary aperture. However, on March 17-19th 2017, we obtained spectral measurements of H2 S(1), CH4, C2H2, C2H4 and C2H6 emission of Jupiter's high latitudes using TEXES on Gemini-North, which has a 8-metre primary aperture. This rare opportunity combines the superior spectral resolving power of TEXES and the high spatial resolution provided by Gemini-North's 8-metre aperture. We will perform a retrieval analyses to determine the 3D distributions of temperature, C2H2, C2H4 and C2H6. The morphology will be compared with near-contemporaneous measurements of H3+ emission from IRTF-SpeX and Juno-JIRAM/UVS to assess the extent of coupling between the stratosphere and ionosphere. In addition, a magnetospheric mapping tool (Vogt et al. 2011, doi:10.1029/2010JA016148) will be used to determine whether small-scale features are likely linked to the solar wind or the magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DPS....4911524P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DPS....4911524P">Cassini UVIS Auroral Observations in 2016 and 2017</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pryor, Wayne R.; Esposito, Larry W.; Jouchoux, Alain; Radioti, Aikaterini; Grodent, Denis; Gustin, Jacques; Gerard, Jean-Claude; Lamy, Laurent; Badman, Sarah; Dyudina, Ulyana A.; Cassini UVIS Team, Cassini VIMS Team, Cassini ISS Team, HST Saturn Auroral Team 2017-10-01 In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high-inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) obtained an extensive set of auroral images, some at the highest spatial resolution obtained during Cassini's long orbital mission (2004-2017). In some cases, two or three spacecraft slews at right angles to the long slit of the spectrograph were required to cover the entire auroral region to form auroral images. We will present selected images from this set showing narrow arcs of emission, more diffuse auroral emissions, multiple auroral arcs in a single image, discrete spots of emission, small scale vortices, large-scale spiral forms, and parallel linear features that appear to cross in places like twisted wires. Some shorter features are transverse to the main auroral arcs, like barbs on a wire. UVIS observations were in some cases simultaneous with auroral observations from the Cassini Imaging Science Subsystem (ISS) the Cassini Visual and Infrared Mapping Spectrometer (VIMS), and the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) that will also be presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060024728&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DFord','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060024728&hterms=Ford&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DFord">Low- to Mid-Latitude X-Ray Emission from Jupiter</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Bhardwaj, Anil; Elsner, Ronald F.; Gladstone, G. Randall; Waite, J. Hunter, Jr.; Branduardi-Raymont, Graziella; Cravens, Thomas E.; Ford, Peter 2006-01-01 The Chandra X-ray Observatory (CXO) observed Jupiter during the period 2003 February 24-26 for approx.40 hours (4 Jupiter rotations), using both the spectroscopy array of the Advanced CCD Imaging Spectrometer (ACIS-S) and the imaging array of the High-Resolution Camera (HRC-I). Two ACIS-S exposures, each approx.8.5 hr long, were separated by an HRC-I exposure of approx.20 hr. The low- to mid-latitude non-auroral disk X-ray emission is much more spatially uniform than the auroral emission. However, the low- to mid-latitude X-ray count rate shows a small but statistically significant hour angle dependence, and is higher in regions of relatively low surface magnetic field strength, confirming ROSAT results. In addition, the spectrum from the low surface field region shows an enhancement in the energy band 1.14- 1.38 keV, perhaps partly due to line emission from that region. Correlation of surface magnetic field strength with count rate is not found for the 2000 December HRC-I data, at a time when solar activity was high. The low- to mid-latitude disk X-ray count rate observed by the HRC-I in the 2003 February observation is about 50% of that observed in 2000 December, roughly consistent with a decrease in the solar activity index (F10.7 cm flux) by a similar amount over the same time period. The low- to mid-latitude X-ray emission does not show any oscillations similar to the -45 minute oscillations sometimes seen from the northern auroral zone. The temporal variation in Jupiter's non-auroral X-ray emission exhibits similarities to variations in solar X-ray flux observed by GOES and TIMED/SEE. The two ACIS-S 0.3-2 keV low- to mid-latitude X-ray spectra are harder than the auroral spectrum, and are different from each other at energies above 0.7 keV, showing variability in Jupiter s non-auroral X-ray emission on a time scale of a day. The 0.3-2.0 keV X-ray power emitted at low- to mid-latitudes is 0.21 GW and 0.39 GW for the first and second ACIS-S exposures, respectively. We suggest that X-ray emission from Jupiter's disk may be largely generated by solar X-rays resonantly and fluorescently scattered in its upper atmosphere, especially at times of high incident solar X-ray flux. However, the correlation of higher count rate with low surface magnetic-field strength indicates the presence of some secondary component, possibly ion precipitation from radiation belts closer to the planet than elsewhere at low- to mid-latitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.U31B0009W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.U31B0009W">Auroral Infrasound Observed at I53US at Fairbanks, Alaska</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wilson, C. R.; Olson, J. V. 2003-12-01 In this presentation we will describe two different types of auroral infrasound recently observed at Fairbanks, Alaska in the pass band from 0.015 to 0.10 Hz. Infrasound signals associated with auroral activity (AIW) have been observed in Fairbanks over the past 30 years with infrasonic microphone arrays. The installation of the new CTBT/IMS infrasonic array, I53US, at Fairbanks has resulted in a greatly increased quality of the infrasonic data with which to study natural sources of infrasound. In the historical data at Fairbanks all the auroral infrasonic waves (AIW) detected were found to be the result of bow waves that are generated by supersonic motion of auroral arcs that contain strong electrojet currents. This infrasound is highly anisotropic, moving in the same direction as that of the auroral arc. AIW bow waves observed in 2003 at I53US will be described. Recently at I53US we have observed many events of very high trace velocity that are comprised of continuous, highly coherent wave trains. These waves occur in the morning hours at times of strong auroral activity. This new type of very high trace velocity AIW appears to be associated with pulsating auroral displays. Pulsating auroras occur predominantly after magnetic midnight (10:00 UT at Fairbanks). They are a usual part of the recovery phase of auroral substorms and are produced by energetic electrons precipitating into the atmosphere. Given proper dark, cloudless sky conditions during the AIW events, bright pulsating auroral forms were sometimes visible overhead. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SoSyR..51..362S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SoSyR..51..362S">Changes in the Martian atmosphere induced by auroral electron precipitation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Shematovich, V. I.; Bisikalo, D. V.; Gérard, J.-C.; Hubert, B. 2017-09-01 Typical auroral events in the Martian atmosphere, such as discrete and diffuse auroral emissions detected by UV spectrometers onboard ESA Mars Express and NASA MAVEN, are investigated. Auroral electron kinetic energy distribution functions and energy spectra of the upward and downward electron fluxes are obtained by electron transport calculations using the kinetic Monte Carlo model. These characteristics of auroral electron fluxes make it possible to calculate both the precipitation-induced changes in the atmosphere and the observed manifestations of auroral events on Mars. In particular, intensities of discrete and diffuse auroral emissions in the UV and visible wavelength ranges (Soret et al., 2016; Bisikalo et al., 2017; Gérard et al., 2017). For these conditions of auroral events, the analysis is carried out, and the contribution of the fluxes of precipitating electrons to the heating and ionization of the Martian atmosphere is estimated. Numerical calculations show that in the case of discrete auroral events the effect of the residual crustal magnetic field leads to a significant increase in the upward fluxes of electrons, which causes a decrease in the rates of heating and ionization of the atmospheric gas in comparison with the calculations without taking into account the residual magnetic field. It is shown that all the above-mentioned impact factors of auroral electron precipitation processes should be taken into account both in the photochemical models of the Martian atmosphere and in the interpretation of observations of the chemical composition and its variations using the ACS instrument onboard ExoMars. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011HGSS....2....1S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011HGSS....2....1S">Danish auroral science history</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Stauning, P. 2011-01-01 Danish auroral science history begins with the early auroral observations made by the Danish astronomer Tycho Brahe during the years from 1582 to 1601 preceding the Maunder minimum in solar activity. Included are also the brilliant observations made by another astronomer, Ole Rømer, from Copenhagen in 1707, as well as the early auroral observations made from Greenland by missionaries during the 18th and 19th centuries. The relations between auroras and geomagnetic variations were analysed by H. C. Ørsted, who also played a vital role in the development of Danish meteorology that came to include comprehensive auroral observations from Denmark, Iceland and Greenland as well as auroral and geomagnetic research. The very important auroral investigations made by Sophus Tromholt are outlined. His analysis from 1880 of auroral observations from Greenland prepared for the significant contributions from the Danish Meteorological Institute, DMI, (founded in 1872) to the first International Polar Year 1882/83, where an expedition headed by Adam Paulsen was sent to Greenland to conduct auroral and geomagnetic observations. Paulsen's analyses of the collected data gave many important results but also raised many new questions that gave rise to auroral expeditions to Iceland in 1899 to 1900 and to Finland in 1900 to 1901. Among the results from these expeditions were 26 unique paintings of the auroras made by the artist painter, Harald Moltke. The expedition to Finland was headed by Dan la Cour, who later as director of the DMI came to be in charge of the comprehensive international geomagnetic and auroral observations made during the Second International Polar Year in 1932/33. Finally, the article describes the important investigations made by Knud Lassen during, among others, the International Geophysical Year 1957/58 and during the International Quiet Sun Year (IQSY) in 1964/65. With his leadership the auroral and geomagnetic research at DMI reached a high international level that came to be the background for the first Danish satellite, Ørsted, successfully launched in 1999 and still in operation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AdSpR..54.1786E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AdSpR..54.1786E">Nonlinear electron-acoustic rogue waves in electron-beam plasma system with non-thermal hot electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Elwakil, S. A.; El-hanbaly, A. M.; Elgarayh, A.; El-Shewy, E. K.; Kassem, A. I. 2014-11-01 The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, non-thermal hot electrons obeying a non-thermal distribution, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles on the electron beam and energetic population parameter are discussed. The results of the present investigation may be applicable in auroral zone plasma. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1366450','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1366450">Renewable Energy Zones for Balancing Siting Trade-offs in India</a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Deshmukh, Ranjit; Wu, Grace C.; Phadke, Amol India’s targets of 175 GW of renewable energy capacity by 2022, and 40% generation capacity from non-fossil fuel sources by 2030 will require a rapid and dramatic increase in solar and wind capacity deployment and overcoming its associated economic, siting, and power system challenges. The objective of this study was to spatially identify the amount and quality of wind and utility-scale solar resource potential in India, and the possible siting-related constraints and opportunities for development of renewable resources. Using the Multi-criteria Analysis for Planning Renewable Energy (MapRE) methodological framework, we estimated several criteria valuable for the selection of sites formore » development for each identified potential "zone", such as the levelized cost of electricity, distance to nearest substation, capacity value (or the temporal matching of renewable energy generation to demand), and the type of land cover. We find that high quality resources are spatially heterogeneous across India, with most wind and solar resources concentrated in the southern and western states, and the northern state of Rajasthan. Assuming India's Central Electricity Regulatory Commission's norms, we find that the range of levelized costs of generation of wind and solar PV resources overlap, but concentrated solar power (CSP) resources can be approximately twice as expensive. Further, the levelized costs of generation vary much more across wind zones than those across solar zones because of greater heterogeneity in the quality of wind resources compared to that of solar resources. When considering transmission accessibility, we find that about half of all wind zones (47%) and two-thirds of all solar PV zones (66%) are more than 25 km from existing 220 kV and above substations, suggesting potential constraints in access to high voltage transmission infrastructure and opportunities for preemptive transmission planning to scale up RE development. Additionally and importantly, we find that about 84% of all wind zones are on agricultural land, which provide opportunities for multiple-uses of land but may also impose constraints on land availability. We find that only 29% of suitable solar PV sites and 15% of CSP sites are within 10 km of a surface water body suggesting water availability as a significant siting constraint for solar plants. Availability of groundwater resources was not analyzed as part of this study. Lastly, given the possible economic benefits of transmission extensions or upgrades that serve both wind and solar generators, we quantified the co-location opportunities between the two technologies and find that about a quarter (28%) of all solar PV zones overlap with wind zones. Using the planning tools made available as part of this study, these multiple siting constraints and opportunities can be systematically compared and weighted to prioritize development that achieves a particular technology target. Our results are limited by the uncertainties associated with the input datasets, in particular the geospatial wind and solar resource, transmission, and land use land cover datasets. As input datasets get updated and improved, the methodology and tools developed through this study can be easily adapted and applied to these new datasets to improve upon the results presented in this study. India is on a path to significantly decarbonize its electricity grid through wind and solar development. A stakeholder-driven, systematic, and integrated planning approach using data and tools such as those highlighted in this study is essential to not only meet the country's RE targets, but to meet them in a cost-effective, and socially and environmentally sustainable way.« less </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM41E2519S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM41E2519S">Effects of Complex Interplanetary Structures on the Dynamics of the Earth's Outer Radiation Belt During the 16-30 September 2014 Period: II) Corotating Solar Wind Stream</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Souza, V. M. C. E. S.; Da Silva, L. A.; Sibeck, D. G.; Alves, L. R.; Jauer, P. R.; Dias Silveira, M. V.; Medeiros, C.; Marchezi, J.; Rockenbach, M.; Baker, D. N.; Kletzing, C.; Kanekal, S. G.; Georgiou, M.; Mendes, O., Jr.; Dal Lago, A.; Vieira, L. E. A. 2015-12-01 We present a case study describing the dynamics of the outer radiation belt for two different solar wind conditions. First, we discuss a dropout of outer belt energetic electron fluxes corresponding to the arrival of an interplanetary coronal mass ejection (ICME) followed by a corotating stream in September 2014. Second, we discuss the reformation of the outer radiation belt that began on September 22nd. We find that the arrival of the ICME and the corotating interaction region that preceded the stream cause a long-duration (many day) dropout of high-energy electrons. The recovery in radiation belt fluxes only begins when the high-speed stream begins to develop IMF Bz fluctuations and auroral activity resumes. Furthermore, during periods in which several consecutive solar wind structures appear, the first structure primes the outer radiation belt prior to the interaction of the subsequent solar wind structures with the magnetosphere. Consequently, the evolution of the outer radiation belt through the solar cycle is significantly affected by the dominant structure of each phase of the cycle. We use energetic electron and magnetic field observations provided by the Van Allen Probes, THEMIS, and GOES missions. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active">19</li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active">20</li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012P%26SS...61...15Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012P%26SS...61...15Y">Influence of upstream solar wind on thermospheric flows at Jupiter</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yates, J. N.; Achilleos, N.; Guio, P. 2012-02-01 The coupling of Jupiter's magnetosphere and ionosphere plays a vital role in creating its auroral emissions. The strength of these emissions is dependent on the difference in speed of the rotational flows within Jupiter's high-latitude thermosphere and the planet's magnetodisc. Using an azimuthally symmetric global circulation model, we have simulated how upstream solar wind conditions affect the energy and direction of atmospheric flows. In order to simulate the effect of a varying dynamic pressure in the upstream solar wind, we calculated three magnetic field profiles representing compressed, averaged and expanded ‘middle’ magnetospheres. These profiles were then used to solve for the angular velocity of plasma in the magnetosphere. This angular velocity determines the strength of currents flowing between the ionosphere and magnetosphere. We examine the influence of variability in this current system upon the global winds and energy inputs within the Jovian thermosphere. We find that the power dissipated by Joule heating and ion drag increases by ∼190% and ∼185% from our compressed to expanded model respectively. We investigated the effect of exterior boundary conditions on our models and found that by reducing the radial current at the outer edge of the magnetodisc, we also limit the thermosphere's ability to transmit angular momentum to this region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA23A2536T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA23A2536T">Seasonal Variation of High-latitude Geomagnetic Activity Revisited</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tanskanen, E.; Hynönen, R.; Mursula, K. 2017-12-01 The coupling of the solar wind and auroral region has been examined by using westward electrojet indices since 1966 - 2014. We have studied the seasonal variation of high-latitude geomagnetic activity in individual years for solar cycles 20 - 24. The classical two-equinox activity pattern in geomagnetic activity was seen in multi-year averages but it was found in less than one third of the years examined. We found that the seasonal variation of high-latitude geomagnetic activity closely follows the solar wind speed. While the mechanisms leading to the two-equinox maxima pattern are in operation, the long-term change of solar wind speed tends to mask the effect of these mechanisms for individual years. We identified the most active and the second most active season based on westward electrojet indices AL (1966 - 2014) and IL (1995 - 2014). The annual maximum is found at either equinox in 2/3 and at either solstice in 1/3 of the years examined. Large cycle-to-cycle variation is found in the seasonal pattern: equinox maxima are more common during cycles 21 and 22 than in cycles 23 or 24. An exceptionally long winter dominance in high-latitude activity and solar wind speed is seen in the declining phase of cycle 23, after the appearance of the long-lasting low-latitude coronal hole. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CSR...151...40T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CSR...151...40T">Nearshore circulation on a sea breeze dominated beach during intense wind events</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Torres-Freyermuth, Alec; Puleo, Jack A.; DiCosmo, Nick; Allende-Arandía, Ma. Eugenia; Chardón-Maldonado, Patricia; López, José; Figueroa-Espinoza, Bernardo; de Alegria-Arzaburu, Amaia Ruiz; Figlus, Jens; Roberts Briggs, Tiffany M.; de la Roza, Jacobo; Candela, Julio 2017-12-01 A field experiment was conducted on the northern Yucatan coast from April 1 to April 12, 2014 to investigate the role of intense wind events on coastal circulation from the inner shelf to the swash zone. The study area is characterized by a micro-tidal environment, low-energy wave conditions, and a wide and shallow continental shelf. Furthermore, easterly trade winds, local breezes, and synoptic-scale events, associated with the passage of cold-fronts known as Nortes, are ubiquitous in this region. Currents were measured concurrently at different cross-shore locations during both local and synoptic-scale intense wind events to investigate the influence of different forcing mechanisms (i.e., large-scale currents, winds, tides, and waves) on the nearshore circulation. Field observations revealed that nearshore circulation across the shelf is predominantly alongshore-directed (westward) during intense winds. However, the mechanisms responsible for driving instantaneous spatial and temporal current variability depend on the weather conditions and the across-shelf location. During local strong sea breeze events (W > 10 m s-1 from the NE) occurring during spring tide, westward circulation is controlled by the tides, wind, and waves at the inner-shelf, shallow waters, and inside the surf/swash zone, respectively. The nearshore circulation is relaxed during intense land breeze events (W ≈ 9 m s-1 from the SE) associated with the low atmospheric pressure system that preceded a Norte event. During the Norte event (Wmax≈ 15 m s-1 from the NNW), westward circulation dominated outside the surf zone and was correlated to the Yucatan Current, whereas wave breaking forces eastward currents inside the surf/swash zone. The latter finding implies the existence of large alongshore velocity shear at the offshore edge of the surf zone during the Norte event, which enhances mixing between the surf zone and the inner shelf. These findings suggest that both sea breezes and Nortes play an important role in sediment and pollutant transport along/across the nearshore of the Yucatan shelf. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860021947&hterms=fenton&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfenton','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860021947&hterms=fenton&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dfenton">Fire control method and analytical model for large liquid hydrocarbon pool fires</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Fenton, D. L. 1986-01-01 The dominate parameter governing the behavior of a liquid hydrocarbon (JP-5) pool fire is wind speed. The most effective method of controlling wind speed in the vicinity of a large circular (10 m dia.) pool fire is a set of concentric screens located outside the perimeter. Because detailed behavior of the pool fire structure within one pool fire diameter is unknown, an analytical model supported by careful experiments is under development. As a first step toward this development, a regional pool fire model was constructed for the no-wind condition consisting of three zones -- liquid fuel, combustion, and plume -- where the predicted variables are mass burning rate and characteristic temperatures of the combustion and plume zones. This zone pool fire model can be modified to incorporate plume bending by wind, radiation absorption by soot particles, and a different ambient air flow entrainment rate. Results from the zone model are given for a pool diameter of 1.3 m and are found to reproduce values in the literature. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.3646S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.3646S">Case Study of Ion Beams Observed By Cluster At Perigee</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sergeev, V.; Sauvaud, J.-A.; Perigee Beam Team During substorms the short beams of ions in the keV-to-tens keV energy range are injected into the auroral flux tubes from the magnetotail (sometimes extending up to >100 keV energy) carrying the information on the source distance, scale-size and temporal history of plasma acceleration. We present observations with the CLUSTER crossing inward the auroral zone flux tubes at ~4Re distance near its perigee during the substorm activity on February 14, 2001. The ion beams cover the same region (poleward half) of the auroral oval where the low-energy ions are extracted from the ionosphere, and where the small-scale transient transverse Alfven waves are observed which carry predominantly the downward parallel Poynting flux into the ionosphere. The multiple beams were basically confirmed to be the transient effects, although some effects including the (spatial) velocity filter and the parallel electric fields (im- posed by quasineutrality requirement) may complicate the interpretation. The gener- ation region of ion beams is not limited to most poleward, newly-reconnected flux tubes; the beam generation region could extend across magnetic field inward by as much as >100km (if mapped to the ionosphere). Surprising variety of injection dis- tances observed nearly simultaneously (ranging between >60 Re and ~10 Re) have been inferred when using the full available energy and time resolution, with shorter injection distances be possibly associated with the flow braking process. The beam multiplicity often displays the apparent ~3 min quasiperiodicity inherent to the basic dissipation process, it was not yet explained by any substorm theory. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000IAUJD...6E..15W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000IAUJD...6E..15W">Scientific interpretation of historical auroral records</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Willis, D. M.; Stephenson, F. R. The available historical auroral records from both Europe and East Asia are examined critically for their relevance in the investigation of long-term variations in both solar activity and the Earth's magnetic field. The early oriental records are sufficiently numerous to allow scientific studies of variations on several time scales. Special attention is paid to the seasonal and secular variations of the early oriental auroral observations. In addition, the oriental auroral records exhibit a clear 27-day recurrence tendency at particular periods of time. A search has been made for examples of strictly simultaneous and indisputably independent observations of the aurora from spatially separated sites in East Asia. This search has yielded nine observations of mid-latitude auroral displays at more than one site in East Asia on the same night. A particular geomagnetic storm that occurred during December in AD 1128 is investigated in detail. Five days after the observation of two large sunspots in England, a red auroral display was observed from Korea. In addition, between the middle of AD 1127 and the middle of AD 1129, five Chinese and five Korean auroral observations were recorded. These provide evidence for recurrent auroral activity on a timescale almost exactly equal to the synodic-solar-rotation period (approximately 27 days). Finally, a new attempt is made to use the oriental historical auroral records to determine the location of the north geomagnetic pole during the European Middle Ages. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-06-01/pdf/2012-13361.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-06-01/pdf/2012-13361.pdf">77 FR 32497 - Grant of Authority for Subzone Status; Mitsubishi Power Systems Americas, Inc. (Wind Turbine...</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a> 2012-06-01 ... DEPARTMENT OF COMMERCE Foreign-Trade Zones Board [Order No. 1832] Grant of Authority for Subzone Status; Mitsubishi Power Systems Americas, Inc. (Wind Turbine Nacelles and Generating Sets) Fort Smith, AR Pursuant to its authority under the Foreign-Trade Zones Act of June 18, 1934, as amended (19 U.S.C. 81a-81u), the Foreign-Trade Zones Board (th... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920068571&hterms=polar+bear&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpolar%2Bbear','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920068571&hterms=polar+bear&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dpolar%2Bbear">Determining the source region of auroral emissions in the prenoon oval using coordinated Polar BEAR UV-imaging and DMSP particle measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Newell, Patrick T.; Meng, CHING-I.; Huffman, Robert E. 1992-01-01 The Polar Beacon Experiment and Auroral Research (Polar BEAR) satellite included the capability for imaging the dayside auroral oval in full sunlight at several wavelengths. Particle observations from the DMSP F7 satellite during dayside auroral oval crossings are compared with approximately simultaneous Polar BEAR 1356-A images to determine the magnetospheric source region of the dayside auroral oval. The source region is determined from the DMSP particle data, according to recent work concerning the classification and identification of precipitation source regions. The close DMSP/Polar BEAR coincidences all occur when the former satellite is located between 0945 and 1000 MLT. Instances of auroral arcs mapping to each of several different regions, including the boundary plasma sheet, the low-latitude boundary layer, and the plasma mantle were found. It was determined that about half the time the most prominent auroral arcs are located at the interfaces between distinct plasma regions, at least at the local time studied here. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950025399','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950025399">Global Ultraviolet Imager (GUVI) investigation</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Christensen, Andrew B. 1995-01-01 This report covers the activities performed under NAS5-32572. The results of those activities are included in this Final Report. TIMED Science Objectives: (1) To determine the temperature, density, and wind structure of the MLTI (mixed layer thermal inertia), including the seasonal and latitudinal variations; and (2) To determine the relative importance of the various radiative, chemical, electrodynamical, and dynamical sources and sinks of energy for the thermal structure of the MLTI. GUVI Science Goals: (1) Determine the spatial and temporal variations of temperature and constituent densities in the lower thermosphere; and (2) Determine the importance of auroral energy sources and solar EUV (extreme ultraviolet) to the energy balance of the region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050060920','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050060920">Application of Remote Sensing to Assess the Impact of Short Term Climate Variability on Coastal Sedimentation</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Menzel, W. Paul; Huh, Oscar K.; Walker, Nan 2004-01-01 The purpose of this joint University of Wisconsin (UW) and Louisiana State University (LSU) project has been to relate short term climate variation to response in the coastal zone of Louisiana in an attempt to better understand how the coastal zone is shaped by climate variation. Climate variation in this case largely refers to variation in surface wind conditions that affect wave action and water currents in the coastal zone. The primary region of focus was the Atchafalaya Bay and surrounding bays in the central coastal region of Louisiana. Suspended solids in the water column show response to wind systems both in quantity (through resuspension) and in the pattern of dispersement or transport. Wind systems associated with cold fronts are influenced by short term climate variation. Wind energy was used as the primary signature of climate variation in this study because winds are a significant influence on sediment transport in the micro-tidal Gilf of Mexico coastal zone. Using case studies, the project has been able to investigate the influence of short term climate variation on sediment transport. Wind energy data, collected daily for National Weather Service (NWS) stations at Lake Charles and New Orleans, LA, were used as an indicator of short term climate variation influence on seasonal time scales. A goal was to relate wind energy to coastal impact through sediment transport. This goal was partially accomplished by combining remote sensing and wind energy data. Daily high resolution remote sensing observations are needed to monitor the complex coastal zone environment, where winds, tides, and water level all interact to influence sediment transport. The NASA Earth Observing System (EOS) era brings hope for documenting and revealing response of the complex coastal transport mosaic through regular high spatial resolution observations from the Moderate resolution Imaging Spectrometer (MODIS) instrument. MODIS observations were sampled in this project for information content and should continue to be viewed as a resource for coastal zone monitoring. The project initialized the effort to transfer a suspended sediment concentration (SSC) algorithm to the MODIS platform for case 2 waters. MODIS enables monitoring of turbid coastal zones around the globe. The MODIS SSC algorithm requires refinements in the atmospheric aerosol contribution, sun glint influence, and designation of the sediment inherent optical properties (IOPs); the framework for continued development is in place with a plan to release the algorithm to the MODIS direct broadcast community. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760014707','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760014707">Study of plasmasphere dynamics using incoherent scatter data from Chatanika, Alaska radar facility</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Shelley, E. G. 1975-01-01 Results of the study of Chatanika incoherent scatter radar data and Lockheed Palo Alto Research Laboratory satellite data are reported. Specific topics covered include: determination of the effective recombination coefficient in the auroral E region; determination of the location of the auroral oval; auroral boundary characteristics; and the relationship of auroral current systems, particle precipitation, visual aurora, and radar aurora. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMNG33A1854P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMNG33A1854P">Learning-based Wind Estimation using Distant Soundings for Unguided Aerial Delivery</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Plyler, M.; Cahoy, K.; Angermueller, K.; Chen, D.; Markuzon, N. 2016-12-01 Delivering unguided, parachuted payloads from aircraft requires accurate knowledge of the wind field inside an operational zone. Usually, a dropsonde released from the aircraft over the drop zone gives a more accurate wind estimate than a forecast. Mission objectives occasionally demand releasing the dropsonde away from the drop zone, but still require accuracy and precision. Barnes interpolation and many other assimilation methods do poorly when the forecast error is inconsistent in a forecast grid. A machine learning approach can better leverage non-linear relations between different weather patterns and thus provide a better wind estimate at the target drop zone when using data collected up to 100 km away. This study uses the 13 km resolution Rapid Refresh (RAP) dataset available through NOAA and subsamples to an area around Yuma, AZ and up to approximately 10km AMSL. RAP forecast grids are updated with simulated dropsondes taken from analysis (historical weather maps). We train models using different data mining and machine learning techniques, most notably boosted regression trees, that can accurately assimilate the distant dropsonde. The model takes a forecast grid and simulated remote dropsonde data as input and produces an estimate of the wind stick over the drop zone. Using ballistic winds as a defining metric, we show our data driven approach does better than Barnes interpolation under some conditions, most notably when the forecast error is different between the two locations, on test data previously unseen by the model. We study and evaluate the model's performance depending on the size, the time lag, the drop altitude, and the geographic location of the training set, and identify parameters most contributing to the accuracy of the wind estimation. This study demonstrates a new approach for assimilating remotely released dropsondes, based on boosted regression trees, and shows improvement in wind estimation over currently used methods. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730023546','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730023546">Analysis of Auroral Data from Nasa's 1968 and 1969 Airborne Auroral Expedition</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> 1973-01-01 Results of a methodical compilation, reduction, and correlated analysis of spectrophotometric data obtained by various scientific groups during NASA's 1968 and 1969 Airborne Auroral Expedition are presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E.106A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E.106A">Problem of Auroral Oval Mapping and Multiscale Auroral Structures</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Antonova, Elizaveta; Stepanova, Marina; Kirpichev, Igor; Vovchenko, Vadim; Vorobjev, Viachislav; Yagodkina, Oksana The problem of the auroral oval mapping to the equatorial plane is reanalyzed taking into account the latest results of the analysis of plasma pressure distribution at low altitudes and at the equatorial plane. Statistical pictures of pressure distribution at low latitudes are obtained using data of DMSP observations. We obtain the statistical pictures of pressure distribution at the equatorial plane using data of THEMIS mission. Results of THEMIS observations demonstrate the existence of plasma ring surrounding the Earth at geocentric distances from ~6 till ~12Re. Plasma pressure in the ring is near to isotropic and its averaged values are larger than 0.2 nPa. We take into account that isotropic plasma pressure is constant along the field line and that the existence of field-aligned potential drops in the region of the acceleration of auroral electrons leads to pressure decrease at low altitudes. We show that most part of quite time auroral oval does not map to the real plasma sheet. It maps to the surrounding the Earth plasma ring. We also show that transverse currents in the plasma ring are closed inside the magnetosphere forming the high latitude continuation of the ordinary ring current. The obtained results are used for the explanation of ring like form of the auroral oval. We also analyze the processes of the formation of multiscale auroral structures including thin auroral arcs and discuss the difficulties of the theories of alfvenic acceleration of auroral electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA43B2655H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA43B2655H">Extremely Nonthermal Monoenergetic Precipitation in the Auroral Acceleration Region: In Situ Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hatch, S.; Chaston, C. C.; Labelle, J. W. 2017-12-01 We report in situ measurements through the auroral acceleration region that reveal extremely nonthermal monoenergetic electron distributions. These auroral primaries are indicative of source populations in the plasma sheet well described as kappa distributions with κ ≲ 2. We show from observations and modeling how this large deviation from Maxwellian form may modify the acceleration potential required to drive current closure through the auroral ionosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P11G..02P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P11G..02P">Cassini UVIS Observations of Saturn during the Grand Finale Orbits</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Pryor, W. R.; Esposito, L. W.; West, R. A.; Jouchoux, A.; Radioti, A.; Grodent, D. C.; Gerard, J. C. M. C.; Gustin, J.; Lamy, L.; Badman, S. V. 2017-12-01 In 2016 and 2017, the Cassini Saturn orbiter executed a final series of high inclination, low-periapsis orbits ideal for studies of Saturn's polar regions. The Cassini Ultraviolet Imaging Spectrograph (UVIS) obtained an extensive set of auroral images, some at the highest spatial resolution obtained during Cassini's long orbital mission (2004-2017). In some cases, two or three spacecraft slews at right angles to the long slit of the spectrograph were required to cover the entire auroral region to form auroral images. We will present selected images from this set showing narrow arcs of emission, more diffuse auroral emissions, multiple auroral arcs in a single image, discrete spots of emission, small scale vortices, large-scale spiral forms, and parallel linear features that appear to cross in places like twisted wires. Some shorter features are transverse to the main auroral arcs, like barbs on a wire. UVIS observations were in some cases simultaneous with auroral observations from the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) that will also be presented. UVIS polar images also contain spectral information suitable for studies of the auroral electron energy distribution. The long wavelength part of the UVIS polar images contains a signal from reflected sunlight containing absorption signatures of acetylene and other Saturn hydrocarbons. The hydrocarbon spatial distribution will also be examined. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EP%26S...67..166A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EP%26S...67..166A">Problems with mapping the auroral oval and magnetospheric substorms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Antonova, E. E.; Vorobjev, V. G.; Kirpichev, I. P.; Yagodkina, O. I.; Stepanova, M. V. 2015-10-01 Accurate mapping of the auroral oval into the equatorial plane is critical for the analysis of aurora and substorm dynamics. Comparison of ion pressure values measured at low altitudes by Defense Meteorological Satellite Program (DMSP) satellites during their crossings of the auroral oval, with plasma pressure values obtained at the equatorial plane from Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite measurements, indicates that the main part of the auroral oval maps into the equatorial plane at distances between 6 and 12 Earth radii. On the nightside, this region is generally considered to be a part of the plasma sheet. However, our studies suggest that this region could form part of the plasma ring surrounding the Earth. We discuss the possibility of using the results found here to explain the ring-like shape of the auroral oval, the location of the injection boundary inside the magnetosphere near the geostationary orbit, presence of quiet auroral arcs in the auroral oval despite the constantly high level of turbulence observed in the plasma sheet, and some features of the onset of substorm expansion. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27656099','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27656099">Problems with mapping the auroral oval and magnetospheric substorms.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Antonova, E E; Vorobjev, V G; Kirpichev, I P; Yagodkina, O I; Stepanova, M V Accurate mapping of the auroral oval into the equatorial plane is critical for the analysis of aurora and substorm dynamics. Comparison of ion pressure values measured at low altitudes by Defense Meteorological Satellite Program (DMSP) satellites during their crossings of the auroral oval, with plasma pressure values obtained at the equatorial plane from Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite measurements, indicates that the main part of the auroral oval maps into the equatorial plane at distances between 6 and 12 Earth radii. On the nightside, this region is generally considered to be a part of the plasma sheet. However, our studies suggest that this region could form part of the plasma ring surrounding the Earth. We discuss the possibility of using the results found here to explain the ring-like shape of the auroral oval, the location of the injection boundary inside the magnetosphere near the geostationary orbit, presence of quiet auroral arcs in the auroral oval despite the constantly high level of turbulence observed in the plasma sheet, and some features of the onset of substorm expansion. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JGRA..10912213S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JGRA..10912213S">Two types of energy-dispersed ion structures at the plasma sheet boundary</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sauvaud, J.-A.; Kovrazhkin, R. A. 2004-12-01 We study two main types of ion energy dispersions observed in the energy range ˜1 to 14 keV on board the Interball-Auroral (IA) satellite at altitudes 2-3 RE at the poleward boundary of the plasma sheet. The first type of structure is named velocity dispersed ion structures (VDIS). It is known that VDIS represent a global proton structure with a latitudinal width of ˜0.7-2.5°, where the ion overall energy increases with latitude. IA data allow to show that VDIS are made of substructures lasting for ˜1-3 min. Inside each substructure, high-energy protons arrive first, regardless of the direction of the plasma sheet boundary crossing. A near-continuous rise of the maximal and minimal energies of consecutive substructures with invariant latitude characterizes VDIS. The second type of dispersed structure is named time-of-flight dispersed ion structures (TDIS). TDIS are recurrent sporadic structures in H+ (and also O+) with a quasi-period of ˜3 min and a duration of ˜1-3 min. The maximal energy of TDIS is rather constant and reaches ≥14 keV. During both poleward and equatorward crossings of the plasma sheet boundary, inside each TDIS, high-energy ions arrive first. These structures are accompanied by large fluxes of upflowing H+ and O+ ions with maximal energies up to 5-10 keV. In association with TDIS, bouncing H+ clusters are observed in quasi-dipolar magnetic field tubes, i.e., equatorward from TDIS. The electron populations generally have different properties during observations of VDIS and TDIS. The electron flux accompanying VDIS first increases smoothly and then decreases after Interball-Auroral has passed through the proton structure. The average electron energy in the range ˜0.5-2 keV is typical for electrons from the plasma sheet boundary layer (PSBL). The electron fluxes associated with TDIS increases suddenly at the polar boundary of the auroral zone. Their average energy, reaching ˜5-8 keV, is typical for CPS. A statistical analysis shows that VDIS are observed mainly during magnetically quiet times and during the recovery phase of substorms, while sporadic and recurrent TDIS are observed during the onset and main phases of substorms and magnetic storms and, although less frequently, during substorm recovery phases. From the slope of the (velocity)-1 versus time dispersions of TDIS, we conclude that they have a sporadic source located at the outer boundary of the central plasma sheet, at distances from 8 to 40 RE in the equatorial plane. The disappearance of the PSBL associated with TDIS can be tentatively linked to a reconfiguration of the magnetotail, which disconnects from the Earth the field lines forming the "quiet" PSBL. We show that VDIS consist of ion beams ejected from an extended current sheet at different distances. These ion beams could be formed in the neutral sheet at distance ranging from ˜30 RE to ˜100 RE from the Earth. Inside each substructure the time-of-flight dispersion of ions generally dominate over any latitudinal dispersion induced by a dawn-dusk electric field. These two main types of energy-dispersed ion structures reflect probably two main states of the magnetotail, quiet and active. Finally, it must be stressed that only ˜49% (246 over 501) of the Interball-Auroral auroral zone-polar cap boundary crossings can be described as VDIS or TDIS. On the other 51% of the crossings of the plasma sheet boundary, no well-defined ion dispersed structures were observed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..121.1391M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..121.1391M">What controls the local time extent of flux transfer events?</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Milan, S. E.; Imber, S. M.; Carter, J. A.; Walach, M.-T.; Hubert, B. 2016-02-01 Flux transfer events (FTEs) are the manifestation of bursty and/or patchy magnetic reconnection at the magnetopause. We compare two sequences of the ionospheric signatures of flux transfer events observed in global auroral imagery and coherent ionospheric radar measurements. Both sequences were observed during very similar seasonal and interplanetary magnetic field (IMF) conditions, though with differing solar wind speed. A key observation is that the signatures differed considerably in their local time extent. The two periods are 26 August 1998, when the IMF had components BZ≈-10 nT and BY≈9 nT and the solar wind speed was VX≈650 km s-1, and 31 August 2005, IMF BZ≈-7 nT, BY≈17 nT, and VX≈380 km s-1. In the first case, the reconnection rate was estimated to be near 160 kV, and the FTE signatures extended across at least 7 h of magnetic local time (MLT) of the dayside polar cap boundary. In the second, a reconnection rate close to 80 kV was estimated, and the FTEs had a MLT extent of roughly 2 h. We discuss the ramifications of these differences for solar wind-magnetosphere coupling. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active">20</li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active">21</li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMSM23B1716S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMSM23B1716S">Prediction of AL and Dst Indices from ACE Measurements Using Hybrid Physics/Black-Box Techniques</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Spencer, E.; Rao, A.; Horton, W.; Mays, L. 2008-12-01 ACE measurements of the solar wind velocity, IMF and proton density is used to drive a hybrid Physics/Black- Box model of the nightside magnetosphere. The core physics is contained in a low order nonlinear dynamical model of the nightside magnetosphere called WINDMI. The model is augmented by wavelet based nonlinear mappings between the solar wind quantities and the input into the physics model, followed by further wavelet based mappings of the model output field aligned currents onto the ground based magnetometer measurements of the AL index and Dst index. The black box mappings are introduced at the input stage to account for uncertainties in the way the solar wind quantities are transported from the ACE spacecraft at L1 to the magnetopause. Similar mappings are introduced at the output stage to account for a spatially and temporally varying westward auroral electrojet geometry. The parameters of the model are tuned using a genetic algorithm, and trained using the large geomagnetic storm dataset of October 3-7 2000. It's predictive performance is then evaluated on subsequent storm datasets, in particular the April 15-24 2002 storm. This work is supported by grant NSF 7020201 </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.........3B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.........3B">Ground and space observations of medium frequency auroral radio emissions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Broughton, Matthew C. The auroral zone is a rich source of natural radio emissions that can be observed in space and at ground-level. By studying these waves, scientists can gain insight into the plasma processes that generate them and use the near-Earth space environment as a large-scale plasma physics laboratory. This thesis uses both ground-level and in situ observations to study two kinds of natural radio emissions. First, we report observations of a new kind of auroral radio emission. The waves have frequencies ranging from 1.3-2.2 MHz, bandwidths ranging from 90-272 kHz, and durations ranging from 16-355 s. Spectral analysis of the waveform data has revealed that the emission has a complex combination of at least three kinds of fine structures. For model auroral electron distributions, calculations indicate that Langmuir waves could be excited at frequencies consistent with observations. The remainder of the thesis discusses auroral medium frequency (MF) burst, an impulsive, broadband natural radio emission observed at ground-level within a few minutes of local substorm onset. LaBelle [2011] proposed that MF burst originates as Langmuir/Z-mode waves on the topside of the ionosphere that subsequently mode convert to L-mode waves and propagate to ground-level. Using continuous waveform measurements and combined observations with the Sondrestrom Incoherent Scatter Radar, we have performed two tests of this mechanism. The results of these tests are consistent with the mechanism described in LaBelle [2011]. A survey of 8,624 half-orbits of the DEMETER spacecraft has revealed 68 observations of bursty MF waves. We have compared the wave properties of these waves to those of MF burst and have found that although it is uncertain, the balance of the evidence suggests that the bursty MF waves observed with DEMETER are the same phenomenon as the ground-level MF burst. Finally, we have used numerical simulations to model both the fine structure of MF burst and to estimate the attenuation the waves would experience due to Landau damping on the topside ionosphere and mode conversion on the bottomside ionosphere. The amount of Landau damping is sensitive to the ratio of secondary to background electrons nse/ne0. Ignoring collisional damping in the lower ionosphere, these calculations suggest that for nse/n e0<0.4%, 0.01-45% of the initial Langmuir wave power would reach ground-level. The above experimental and numerical studies constrain the conditions under which MF burst could plausibly originate as Langmuir/Z-mode waves on the topside of the ionosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990Icar...85..216B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990Icar...85..216B">Auroral and photoelectron fluxes in cometary ionospheres</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Bhardwaj, A.; Haider, S. A.; Spinghal, R. P. 1990-05-01 The analytical yield spectrum method has been used to ascertain photoelectron and auroral electron fluxes in cometary ionospheres, with a view to determining the effects of cometocentric distances, solar zenith angle, and solar minimum and maximum conditions. Auroral electron fluxes are thus calculated for monoenergetic and observed primary electron spectra; auroral electrons are found to make a larger contribution to the observed electron spectrum than EUV-generated photoelectrons. Good agreement is established with extant theoretical works. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.4648G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.4648G">A Statistical Survey of the 630.0-nm Optical Signature of Periodic Auroral Arcs Resulting From Magnetospheric Field Line Resonances</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Gillies, D. Megan; Knudsen, David; Rankin, Robert; Milan, Stephen; Donovan, Eric 2018-05-01 Advances in networks of ground-based optical instrumentation have enabled us to identify over 400 examples of auroral arcs with an infrequently observed, temporally periodic auroral morphology. This study focuses on these arcs observed via the 630-nm ("redline") auroral emission wavelength and connects them to global magnetospheric wave modes known as field line resonances (FLRs). We show that optical redline FLR auroral arcs occur most frequently near 20 and 4 magnetic local time, in contrast to nonperiodic redline arcs, which occur most frequently near midnight. We find that this periodic type of auroral arc is rare, occurring in approximately 5% of redline aurora observed by the Redline Emission Geospace Observatory all-sky imagers. We also show Swarm satellite observations of two separate instances of 630-nm FLR arcs with strong upward field-aligned currents of the order of 3-6 μA/m2. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750050944&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dnike','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750050944&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dnike">Simultaneous measurements of auroral particles and electric currents by a rocket-borne instrument system - Introductory remarks</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Anderson, H. R.; Cloutier, P. A. 1975-01-01 A rocket-borne experiment package has been designed to obtain simultaneous in situ measurements of the pitch angle distributions and energy spectra of primary auroral particles, the flux of neutral hydrogen at auroral energies, the electric currents flowing in the vicinity of the auroral arc as determined from vector magnetic data, and the modulation of precipitating electrons in the frequency range 0.5-10 MHz. The experiment package was launched by a Nike-Tomahawk rocket from Poker Flat, Alaska, at 0722 UT on Feb. 25, 1972, over a bright auroral band. This paper is intended to serve as an introduction to the detailed discussion of results given in the companion papers. As such it includes a brief review of the general problem, a discussion of the rocket instrumentation, a delineation of the auroral and geomagnetic conditions at the time of launch, and comments on the overall payload performance. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.2241G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.2241G">The Effect of Subauroral Polarization Streams on Ionosphere and Thermosphere During the 2015 St. Patrick's Day Storm: Global Ionosphere-Thermosphere Model Simulations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Guo, Jia-Peng; Deng, Yue; Zhang, Dong-He; Lu, Yang; Sheng, Cheng; Zhang, Shun-Rong 2018-03-01 Using the Millstone Hill incoherent scatter radar observations during 2015 St. Patrick's Day storm, subauroral polarization streams (SAPSs) have been specified in the nonhydrostatic Global Ionosphere-Thermosphere Model simulations. The results reveal that the effect of SAPS on the coupled thermosphere-ionosphere system includes the following: (1) Sudden frictional heating of SAPS results in acoustic-gravity waves in the thermosphere. The vertical oscillation is localized, while the meridional disturbance propagates poleward and equatorward. (2) The SAPS-associated horizontal wind field includes an enhanced westward wind within SAPS channel and a twin of vortex-like winds north (clockwise) and south (anticlockwise) of subauroral latitudes. (3) Due to the neutral-ion drag, ions in the vicinity of SAPS channel oscillate vertically with neutrals, resulting in a perturbation of 0.3 TECu in ionospheric total electron content. The SAPS-induced traveling atmospheric disturbances can elevate the plasma and increase the total electron content in midlatitude ionosphere. (4) It is confirmed that the Coriolis force can contribute to the poleward turning of the neutral wind during the post-SAPS interval. In addition, the traveling atmospheric disturbance induced by the variation of auroral input and high-latitude convection is possibly the primary cause of the poleward neutral wind surge during the magnetic storm on 17-18 March 2015. The combination of the two factors can make the northward meridional wind surge reach a magnitude of 100 m/s. This study improves our understanding of the SAPS's effect on neutral dynamics and ion-neutral coupling processes during geomagnetically disturbed intervals. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA590709','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA590709">Investigation of the Representation of OLEs and Terrain Effects Within the Coastal Zone in the EDMF Parameterization Scheme: An Airborne Doppler Wind Lidar Perspective</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2013-10-07 OLEs and Terrain Effects Within the Coastal Zone in the EDMF Parameterization Scheme: An Airborne Doppler Wind Lidar Perspective Annual Report Under...UPP related investigations that will be carried out in Year 3. RELATED PROJECTS ONR contract to study the utilization of Doppler wind lidar (DWL...MATERHORN2012) Paper presented at the Coherent Laser Radar Conference, June 2013 Airborne DWL investigations of flow over complex terrain (MATERHORN </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050212155','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050212155">Correlation Between Low Frequency Auroral Kilometric Radiation (AKR) and Auroral Structures</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Paxamickas, Katherine A.; Green, James L.; Gallagher, Dennis L.; Boardsen, Scott; Mende, Stephen; Frey, Harald; Reinisch, Bodo W. 2005-01-01 Auroral Kilometric Radiation (AKR) is a radio wave emission that has long been associated with auroral activity. AKR is normally observed in the frequency range from -60 - 600 kHz. Low frequency AKR (or LF-AKR) events are characterized as a rapid extension of AKR related emissions to 30 kHz or lower in frequency for typically much less than 10 minutes. LF-AKR emissions predominantly occur within a frequency range of 20 kHz - 30 kHz, but there are LF-AKR related emissions that reach to a frequency of 5 kHz. This study correlates all instances of LF-AKR events during the first four years of observations from the IMAGE spacecraft's Radio Plasma Imager (WI) instrument with auroral observations from the wideband imaging camera (WIC) onboard IMAGE. The correlation between LF-AKR occurrence and WIC auroral observations shows that in the 295 confirmed cases of LF-AKR emissions, bifurcation of the aurora is seen in 74% of the cases. The bifurcation is seen in the dusk and midnight sectors of the auroral oval, where AKR is believed to be generated. The polarization of these LF-AKR emissions has yet to be identified. Although LF-AKR may not be the only phenomena correlated with bifurcated auroral structures, bifurcation will occur in most instances when LF-AKR is observed. The LF-AKR emissions may be an indicator of specific auroral processes sometimes occurring during storm-time conditions in which field-aligned density cavities extend a distance of perhaps 5-6 RE tailward from the Earth for a period of 10 minutes or less. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...10630363T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...10630363T">Seasonal variations of the ionospheric total electron content in Asian equatorial anomaly regions</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tsai, Ho-Fang; Liu, Jann-Yenq; Tsai, Wei-Hsiung; Liu, Chao-Han; Tseng, Ching-Liang; Wu, Chin-Chun 2001-12-01 The ionospheric total electron contents (TEC) in both northern and southern equatorial anomaly regions are examined by using the Global Positioning System (GPS) in Asian area. The TEC contour charts obtained at YMSM (25.2°N, 121.6°E 14.0°N geomagnetic) and DGAR (7.3°S, 72.4°E 16.2°S geomagnetic) stations in 1997, solar minimum, are investigated. It is found that the ionospheric crests manifest remarkable seasonal variations. The TEC values on both northern and southern equatorial anomaly crests yield their maximum values during the vernal and autumnal months, but the winter anomaly does not appear in the southern region. Results show that both crests are fully developed around midday in winter, postnoon in equinoxes and late afternoon in summer, and the two crests move significantly equatorward in winter but slightly poleward in summer and autumn. These phenomena can be fully explained by a combined theory of the transequatorial neutral wind, the subsolar point, and the auroral equatorward wind. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850054019&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagnetic%2Bcooling','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850054019&hterms=magnetic+cooling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagnetic%2Bcooling">A theoretical study of the global F region for June solstice, solar maximum, and low magnetic activity</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sojka, J. J.; Schunk, R. W. 1985-01-01 A time-dependent, three-dimensional, multi-ion model of the ionospheric F region at 120-800 km altitude is presented. Account is taken of field-aligned diffusion, cross-field electrodynamic drifts in equatorial and high latitude regions, interhemispheric flow, thermospheric winds, polar wind escape, energy-dependent chemical reactions and neutral composition changes. Attention is also given to the effects of ion production by solar EUV radiation and auroral precipitation, thermal conduction, diffusion-thermal heat flow, local heating and cooling processes, offsets between the geomagnetic and geographic poles, and bending of field lines near the magnetic equator. The model incorporates all phenomena described by previous models and can be applied to tracing magnetic storm and substorm disturbances from high to low latitudes on a global scale. Sample results are provided for ionospheric features during a June solstice, the solar maximum and in a period of low geomagnetic activity. The model will eventually be used to study coupled ionosphere-thermosphere activity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870027662&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dearth%2Bmagnetic%2Bfield','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870027662&hterms=earth+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dearth%2Bmagnetic%2Bfield">An MHD simulation of the effects of the interplanetary magnetic field By component on the interaction of the solar wind with the earth's magnetosphere during southward interplanetary magnetic field</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Ogino, T.; Walker, R. J.; Ashour-Abdalla, M.; Dawson, J. M. 1986-01-01 The interaction between the solar wind and the earth's magnetosphere has been studied by using a time-dependent three-dimensional MHD model in which the IMF pointed in several directions between dawnward and southward. When the IMF is dawnward, the dayside cusp and the tail lobes shift toward the morningside in the northern magnetosphere. The plasma sheet rotates toward the north on the dawnside of the tail and toward the south on the duskside. For an increasing southward IMF component, the plasma sheet becomes thinner and subsequently wavy because of patchy or localized tail reconnection. At the same time, the tail field-aligned currents have a filamentary layered structure. When projected onto the northern polar cap, the filamentary field-aligned currents are located in the same area as the region 1 currents, with a pattern similar to that associated with auroral surges. Magnetic reconnection also occurs on the dayside magnetopause for southward IMF. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.2398B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.2398B">Diurnal Variations in Global Joule Heating Morphology and Magnitude Due To Neutral Winds</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Billett, D. D.; Grocott, A.; Wild, J. A.; Walach, M.-T.; Kosch, M. J. 2018-03-01 In the polar ionosphere, variations in Joule heating are significantly controlled by changes in plasma convection, such as that brought about by changes in the interplanetary magnetic field. However, another important consideration when calculating Joule heating is the velocity difference between this plasma and the neutral thermosphere colocated with the ionosphere. Neutral wind data are often difficult to obtain on a global scale; thus, Joule heating has often previously been calculated assuming that neutral velocities are small and can therefore be neglected. Previous work has shown the effect of neutral winds on Joule heating estimations to be more significant than originally thought; however, the diurnal variations of the neutrals due to changes in solar pressure gradients and Coriolis forces have yet to have their impact on Joule heating assessed. We show this universal time effect to be significant in calculating Joule heating and thus can differ significantly from that calculated by neglecting the neutrals. In this study, we use empirical models for the neutral wind, conductivities, and magnetic field to create Northern Hemispheric patterns of Joule heating for approximately 800,000 individual plasma convection patterns generated using data from the Super Dual Auroral Radar Network. From this, a statistical analysis of how Joule heating varies in morphology and magnitude with universal time is shown for differing seasons and levels of geomagnetic activity. We find that neutral winds do play a significant role in the morphology and total energy output of Joule heating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA34A..05L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA34A..05L">Impact of high-latitude energy input on the mid- and low-latitude ionosphere and thermosphere</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lu, G.; Sheng, C. 2017-12-01 High-latitude energy input has a profound impact on the ionosphere and thermosphere especially during geomagnetic storms. Intense auroral particle precipitation ionizes neutral gases and modifies ionospheric conductivity; collisions between neutrals and fast-moving ions accelerate the neutral winds and produce Joule frictional heating; and the excess Joule and particle heating causes atmospheric upwelling and changes neutral composition due to the rising of the heavier, molecular-rich air. In addition, impulsive Joule heating launches large-scale gravity waves that propagate equatorward toward middle and low latitudes and even into the opposite hemisphere, altering the mean global circulation of the thermosphere. Furthermore, high-latitude electric field can also directly penetrate to lower latitudes under rapidly changing external conditions, causing prompt ionospheric variations in the mid- and low-latitude regions. To study the effects of high-latitude energy input, we apply the different convection and auroral precipitation patterns based on both empirical models and the AMIE outputs. We investigate how the mid- and low-latitude regions respond to the different specifications of high-latitude energy input. The main purpose of the study is to delineate the various dynamical, electrodynamical, and chemical processes and to determine their relative importance in the resulting ionospheric and thermospheric properties at mid and low latitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM54A..07L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM54A..07L">Effects of Auroral Potential Drops on Field-Aligned Currents and Nightside Reconnection Dynamos</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lotko, W.; Xi, S.; Zhang, B.; Wiltberger, M. J.; Lyon, J. 2016-12-01 The reaction of the magnetosphere-ionosphere system to dynamic auroral potential drops is investigated using the Lyon-Fedder-Mobarry global model and, for the first time in a global simulation, including the dissipative load of field-aligned potential drops in the low-altitude boundary condition. This extra load reduces the demand for field-aligned current (j||) from nightside reconnection dynamos. The system adapts by forcing the nightside x-line closer to Earth to reduce current lensing (j||/B = constant) at the ionosphere, with the plasma sheet undergoing additional contraction during substorm recovery and steady magnetospheric convection. For steady and moderate solar wind driving and with constant ionospheric conductance, the cross-polar cap potential and hemispheric field-aligned current are lower by approximately the ratio of the peak field-aligned potential drop to the cross polar cap potential (10-15%) when potential drops are included. Hemispheric ionospheric Joule dissipation is less by 8%, while the area-integrated, average work done on the fluid by the reconnecting magnetotail field increases by 50% within |y| < 8 RE. Effects on the nightside plasma sheet include: (1) an average x-line 4 RE closer to Earth; (2) a 12% higher mean reconnection rate; and (3) dawn-dusk asymmetry in reconnection with a 17% higher rate in the premidnight sector. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRA..12111129X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRA..12111129X">Effects of auroral potential drops on plasma sheet dynamics</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Xi, Sheng; Lotko, William; Zhang, Binzheng; Wiltberger, Michael; Lyon, John 2016-11-01 The reaction of the magnetosphere-ionosphere system to dynamic auroral potential drops is investigated using the Lyon-Fedder-Mobarry global model including, for the first time in a global simulation, the dissipative load of field-aligned potential drops in the low-altitude boundary condition. This extra load reduces the field-aligned current (j||) supplied by nightside reconnection dynamos. The system adapts by forcing the nightside X line closer to Earth, with a corresponding reduction in current lensing (j||/B = constant) at the ionosphere and additional contraction of the plasma sheet during substorm recovery and steady magnetospheric convection. For steady and moderate solar wind driving and with constant ionospheric conductance, the cross polar cap potential and hemispheric field-aligned current are lower by approximately the ratio of the peak field-aligned potential drop to the cross polar cap potential (10-15%) when potential drops are included. Hemispheric ionospheric Joule dissipation is less by 8%, while the area-integrated, average work done on the fluid by the reconnecting magnetotail field increases by 50% within |y| < 8 RE. Effects on the nightside plasma sheet include (1) an average X line 4 RE closer to Earth; (2) a 12% higher mean reconnection rate; and (3) dawn-dusk asymmetry in reconnection with a 17% higher rate in the premidnight sector. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880064020&hterms=Classical+Perspectives&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DClassical%2BPerspectives','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880064020&hterms=Classical+Perspectives&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DClassical%2BPerspectives">The terrestrial plasma source - A new perspective in solar-terrestrial processes from Dynamics Explorer</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chappell, Charles R. 1988-01-01 The geospace environment has been viewed as a mixing bowl for plasmas of both solar and terrestrial origin. The present perspective on the nature of the supply mechanisms has undergone a radical evolution over the past decade, particularly during the five years of the Dynamics Explorer mission. During this period, the terrestrial source has increased in importance in both magnitude and character of ionospheric outflow. These outflows include the classical polar wind, the cleft ion fountain, the auroral ion fountain, and the polar cap. The earth can be envisioned as a multifaceted fountain which ejects particles from different spatial locations spread around the globe. These particles exhibit a range of masses from 1 to 32 amu and a range of energies from 1 eV to 10 keV. The total flux of this ionospheric outflow is very large: adequate to supply the entire magnetospheric particle population. And the implications of the outflow are significant across a broad spectrum of solar-terrestrial processes ranging from sources of magnetospheric plasmas, to influences on ionospheric density and temperature structure, to energy transfer in phenomena such as stable auroral red arcs. The Dynamics Explorer mission has made a major contribution in the characterization of the terrestrial plasma source. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050182916','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050182916">Complexity and Intermittent Turbulence in Space Plasmas</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chang, Tom; Tam, Sunny W. Y.; Wu, Cheng-Chin 2004-01-01 Sporadic and localized interactions of coherent structures arising from plasma resonances can be the origin of "complexity" of the coexistence of non- propagating spatiotemporal fluctuations and propagating modes in space plasmas. Numerical simulation results are presented to demonstrate the intermittent character of the non-propagating fluctuations. The technique of the dynamic renormalization-group is introduced and applied to the study of scale invariance of such type of multiscale fluctuations. We also demonstrate that the particle interactions with the intermittent turbulence can lead to the efficient energization of the plasma populations. An example related to the ion acceleration processes in the auroral zone is provided. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPlPh..81b9004E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPlPh..81b9004E">Effect of electron beam on the properties of electron-acoustic rogue waves</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> El-Shewy, E. K.; Elwakil, S. A.; El-Hanbaly, A. M.; Kassem, A. I. 2015-04-01 The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, Maxwellian hot electrons, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles and the associated electric field on the carrier wave number, normalized density of hot electron and electron beam, relative cold electron temperature and relative beam temperature are discussed. The results of the present investigation may be applicable in auroral zone plasma. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMSM43A1687L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMSM43A1687L">First results from the Blackstone HF radar in support of THEMIS</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lester, M.; Ruohoniemi, J. M.; Baker, J. B.; Barnes, R. J.; Clauer, C. R.; Greenwald, R. A.; Grocott, A.; Milan, S. E.; Yeoman, T. K. 2008-12-01 A new HF radar has been constructed and built in Blackstone, VA, as part of the SuperDARN/StormDARN programme specifically with the purpose of providing coverage over the Canadian ground sector in THEMIS. The new radar began operations in February 2008, an optimum time to support the first THEMIS tail campaign. This paper will discuss the importance of having radars at lower latitudes than the auroral zone locations of SuperDARN for substorm studies. Furthermore, the paper will also present the first results from this radar together with other SuperDARN observations during the THEMIS tail period. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA191164','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA191164">Coordinated Ground and Space Measurements of Auroral Surge over South Pole.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 1988-02-01 3y V. Coordinated Ground and Space Measurements of co an Auroral Surge over South Pole T. J. ROSENBERG and D. L. DETRICK Institute for Physical...Measurements of an Auroral Surge over South Pole 12. PERSONAL AUTHOR(S) Rosenberg, T. J., and DetrickD. L., University of Maryland; Mizera, Paul F., 13a. TYPE...premidnight auroral surge over Amundsen-Scott South Pole station. The set of near-simultaneous measurements provides an excellent opportunity to gain a </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active">21</li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active">22</li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996A%26A...305..669L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996A%26A...305..669L">A coherent nonlinear theory of auroral Langmuir-Alfven-whistler (LAW) events in the planetary magnetosphere.</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lopes, S. R.; Chian, A. C.-L. 1996-01-01 A coherent nonlinear theory of three-wave coupling involving Langmuir, Alfven and whistler waves is formulated and applied to the observation of auroral LAW events in the planetary magnetosphere. The effects of pump depletion, dissipation and frequency mismatch in the nonlinear wave dynamics are analyzed. The relevance of this theory for understanding the fine structures of auroral whistler-mode emissions and amplitude modulations of auroral Langmuir waves is discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRA..118..685I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRA..118..685I">The Heppner-Maynard Boundary measured by SuperDARN as a proxy for the latitude of the auroral oval</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Imber, S. M.; Milan, S. E.; Lester, M. 2013-02-01 We present a statistical study relating the latitude of the auroral oval measured by the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) SI-12 proton auroral camera to that of the Heppner-Maynard Boundary (HMB) determined from Super Dual Auroral Radar Network (SuperDARN) data during the period 2000-2002. The HMB represents the latitudinal extent of the ionospheric convection pattern. The oval latitude from the proton auroral images is determined using the method of Milan et al. (2009a), which fits a circle centered on a point 2° duskward and 5° antisunward of the magnetic pole. The auroral latitude at midnight is determined for those images where the concurrent SuperDARN northern hemisphere maps contain more than 200 data points such that the HMB is well-defined. The statistical study comprises over 198,000 two-minute intervals, and we find that the HMB is located on average 2.2° equatorward of the proton auroral latitude. A superposed epoch analysis of over 2500 substorms suggests that the separation between the HMB and the oval latitude increases slightly during periods of high geomagnetic activity. We suggest that during intervals where there are no auroral images available, the HMB latitude and motion could be used as a proxy for that of the aurora, and therefore provide information about motions of the open/closed field line boundary. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSA31D2364C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSA31D2364C">Dynamics of the High-latitude Ionospheric Irregularities During the 2015 St. Patrick's Day Storm</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Cherniak, I.; Zakharenkova, I.; Redmon, R. J.; Andrzej, K. 2015-12-01 We presents results on the study of the high-latitude ionospheric irregularities observed in worldwide GPS data during the St. Patrick's Day geomagnetic storm (March 17, 2015). Multi-site GPS observations from more than 2500 ground-based GPS stations were used to analyze the dynamics of the ionospheric irregularities in the Northern and Southern Hemispheres. The most intense ionospheric irregularities lasted for more than 24 hours starting at 07 UT of March 17. This period correlates well with an increase of the auroral Hemispheric Power index. We find hemispheric asymmetries in the intensity and spatial structure of the ionospheric irregularities. Over North America the ionospheric irregularities zone expanded equatorward below ~45°N geographic latitude. Additionally, the strong mid and high latitude GPS phase irregularities in the auroral oval were found to be related to the formation of storm enhanced density, polar tongues of ionization and deepening of the main ionospheric trough through upper atmosphere ionization by energetic particle precipitations. Significant increases in the intensity of the irregularities within the polar cap region of both hemispheres were associated with the formation and evolution of the SED/TOI structures and polar patches. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27812796','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27812796">Constraints on Development of Wind Energy in Poland due to Environmental Objectives. Is There Space in Poland for Wind Farm Siting?</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Hajto, Małgorzata; Cichocki, Zdzisław; Bidłasik, Małgorzata; Borzyszkowski, Jan; Kuśmierz, Agnieszka 2017-02-01 The objective of the study was to evaluate spatial effects of adopting environmental criteria for wind farm siting, i.e., the criteria related to the settlement system and those with regards to landscape values. The set of criteria was elaborated on the basis of literature and experience-based knowledge. Some of the criteria selected are legally binding. The analyses were carried out with the use of GIS tools. Settlement areas with 1000 and 2000 m wide buffer zones, and the areas with the highest landscape values, were assumed as particularly sensitive receptors to wind farm impacts. The results show significant constraints on wind farm siting in Poland. Although the constraints are regionally diversified, they concern 93.9 % of the total country area (1000 m buffer zone) or 99.1 % (2000 m buffer zone). Presumably even greater constraints would be revealed by an additional detailed analysis at a local level. The constraints on wind farm siting in Poland cannot be decreased, because of both social attitudes and demand for appropriate environmental standards, which should be taken into account in spatial and energy policies at all decision making level. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-08-18/pdf/2011-21143.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-08-18/pdf/2011-21143.pdf">76 FR 51349 - Foreign-Trade Zone 72-Indianapolis, IN; Application for Manufacturing Authority, Brevini Wind USA...</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a> 2011-08-18 ...--Indianapolis, IN; Application for Manufacturing Authority, Brevini Wind USA, Inc., (Wind Turbine Gear Boxes... Airport Authority, grantee of FTZ 72, requesting manufacturing authority on behalf of Brevini Wind USA, Inc. (Brevini), to manufacture wind turbine gear boxes under FTZ procedures within FTZ 72. The... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSA51B2392M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSA51B2392M">Association between substorm onsets in auroral all-sky images and geomagnetic Pi2pulsations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Miura, T.; Ieda, A.; Teramoto, M.; Kawashima, T. 2017-12-01 Substorms are explosive disturbances in the magnetosphere and ionosphere of Earth. Substorm onsets are often identified usingsudden auroral brightenings (auroral breakup) or geomagnetic Pi2 pulsations. These auroral brightenings and Pi2 pulsations aresupposed to occur simultaneously within approximately 1 min of each other. However, as auroral brightenings typically includea two-stage development, this simultaneity is not straightforward. In this study, we clarify the correspondence between Pi2 pulsations and auroral brightenings, including the two-stage development.The first stage of the development is the sudden brightening of an auroral arc near the midnight (initial brightening)and the second stage is the poleward expansion of the auroral arc. We compared all-sky images (3 s resolution) in Canada andgeomagnetic observations (0.5-1 s resolution) in North and Central America, using data from the THEMIS project. In this study,we examined three substorms events that exhibit evidence of the two-stage auroral development. In the first event (4 March 2008), an auroral initial brightening occurred at 0533:57 UT and a poleward expansion was observedat 0538:12 UT (4 min after the initial brightening) in Gillam (magnetic latitude:66.0 °, longitude:333 °, MLT:22.9). In contract,the Pi2 pulsation started at 0539:30 UT, which is closer to the time of the poleward expansion, in Carson City (magnetic latitude:45.0 °, longitude:304 °). and San Juan (magnetic latitude:27.9 °, longitude:6.53 °). Thus, we consider this Pi2 pulsation ascorresponding to the poleward expansion rather than the initial brightening. This correspondence was also seen in the other twoevents, suggesting that it is not exceptional. We interpret that the Pi2 pulsation corresponds to the poleward expansion becauseboth are caused by the magnetic field dipolarization, which is a drastic change that propagates from low- to high-latitude fieldlines. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970023975','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970023975">Large Enhancements in the O/N2 Ratio in the Evening Sector of the Winter Hemisphere During Geomagnetic Storms</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Burns, A. G.; Killeen, T. L.; Carignan, G. R.; Roble, R. G. 1995-01-01 In this paper, we have looked for enhancements of the O/N2 ratio in data measured by the Dynamics Explorer 2 (DE 2) satellite in the middle latitudes of the winter hemisphere, based on a prediction that was made by the National Center for Atmospheric Research thermosphere/tonosphere general circulation model (NCAR-TIGCM) that such increases occur. The NCAR-TIGCM predicts that these enhancements should be seen throughout the low latitude region and in many middle latitude locations, but that the enhancements in O/N2 are particularly strong in the middle-latitude, evening-to-midnight sector of the winter hemisphere. When this prediction was used to look for these effects in DE 2 NACS (neutral atmosphere composition spectrometer) data, large enhancements in the O/N2 ratio (approx. 50 to 90%) were seen. These enhancements were observed during the main phase of a storm that occurred on November 24, 1982, and were seen in the same region of the winter hemisphere predicted by the NCAR-TIGCM. They are partially the result of the depletion of N2 and, as electron loss is dependent on dissociative recombination at F(sub 2) altitudes, they have implications for electron densities in this area. Parcel trajectories, which have been followed through the NCAR-TIGCM history file for this event, show that large O/N2 enhancements occur in this limited region in the winter hemisphere for two reasons. First, these parcels of air are decelerated by the antisunward edge of the ion convection pattern; individual parcels converge and subsidence occurs. Thus molecular-nitrogen-poor air is brought from higher to lower heights. Because neutral parcels that are found a little poleward of the equatorial edge of the eveningside convection pattern are swept inward toward the center of the auroral oval, the enhancements occur only in a very limited range of latitudes. Second, nitrogen-poor air is transported from regions close to the magnetic pole in the winter hemisphere. During geomagnetic storms, enhanced meridional winds are driven by the increased pressure-gradient force that is associated with intensified Joule heating in the auroral oval. These pressure-driven winds decrease rapidly on the dayside beyond the auroral oval where the parcels originate, limiting the region into which the parcels can be transported. Thus these two processes drive values of O/N2 in a limited region of the winter hemisphere, and reinforce only in the evening sector, causing large changes in this region. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA405592','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA405592">Characterization of the Auroral Electrojet and the Ambient and Modified D Region for HAARP Using Long-Path VLF Diagnostics</a> <a target="_blank" rel="noopener noreferrer" href="http://www.dtic.mil/">DTIC Science & Technology</a> 2001-03-15 order to characterize the auroral electrojet and the ambient and modified D-region directly above and near the HAARP (High Frequency Active Auroral...near the HAARP facility and along the west coast of Alaska. In addition in order to characterize the auroral electrojet on a continental scale and to...United States and Canada. Data from the complete array of D-region diagnostic systems was acquired during a number of Fall and Spring HAARP campaigns </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790042601&hterms=relationship+form&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Drelationship%2Bform','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790042601&hterms=relationship+form&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Drelationship%2Bform">Relationships between particle precipitation and auroral forms</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Burch, J. L.; Winningham, J. D. 1978-01-01 The paper discusses recent measurements pertaining to the relationship between high-latitude particle (electron) precipitation and auroras. The discussion covers three topics: the large-scale relationships between auroral forms and the particle populations of the magnetosphere as determined from satellite measurements; (2) the relationship between satellite and sounding-rocket observations, particularly field-aligned pitch-angle distributions and upward field-aligned currents measured in the vicinity of auroral forms; and (3) recent results on the interaction of auroral electrons with the atmosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920019668','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920019668">Theoretical and experimental studies relevant to interpretation of auroral emissions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Keffer, Charles E. 1992-01-01 The results obtained in the second year of a three year collaborative effort with MSFC are summarized. A succession of experimental studies was completed to determine the effects of the natural and induced space vehicle environment on the measurement of auroral images from space-based platforms. In addition, a global model which incorporates both auroral and dayglow emission sources is being developed to allow interpretation of measured auroral emissions. A description of work completed on these two tasks is presented. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.6218E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.6218E">Cusp observations with Cluster and THEMIS in preparation for the SMILE mission</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Escoubet, C.-Philippe 2017-04-01 Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a novel self-standing mission, being designed in collaboration between ESA and the Chinese Academy of Science. Its objective is to observe solar wind-magnetosphere coupling via simultaneous in situ solar wind/magnetosheath plasma and magnetic field measurements, soft X-Ray images of the magnetosheath and polar cusps, and UV images of global auroral distributions. The observations of the cusps and magnetosheath with the X-ray imager are possible thanks to the relatively recent discovery of solar wind charge exchange (SWCX) X-ray emissions, first at comets and subsequently in the vicinity of the Earth's magnetosphere. To prepare for the mission, we must determine the cusp's expected morphology, motion, and in situ properties (density, velocity, temperature). We have selected a series of Cluster cusp crossings that define these properties and can therefore be used to estimate X-ray emissions across the width of the cusp for different IMF orientations. We will show that the peak soft X-ray emissions occur near the centre of the cusp where ion densities maximize. We then show that the integral lines of sight emissions through the cusp are a factor of 2.4 times larger for IMF-Bz northward than for IMF-Bz southward. The mid-altitude cusp is a factor of 7 brighter than the exterior cusp. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950022709','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950022709">Solar system plasma waves</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Gurnett, Donald A. 1995-01-01 An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140008813','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140008813">A Novel Concept to Explore the Coupling of the Solar-Terrestrial System</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spann, James 2014-01-01 A revolutionary opportunity to explore the consequences of reconnection in the ionosphere as never before will be presented. It is a revolutionary opportunity to explore key Aeronomy emissions on a global scale with spatial and temporal resolution not possible today. For example, observations of the signature of dayside merging and nightside reconnection that are reflected in the auroral oval evolution during disturbed periods and quiet times, will be described; observations that will open a window of discovery for coupling phenomena within Geospace and with the solar wind. The description of this new concept will be presented, and its impact and contribution to understanding magnetic merging will be discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SunGe..12..111G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SunGe..12..111G">Auroras observations of the MAIN in Apatity during 2014/15 winter season</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Guineva, V.; Despirak, I.; Kozelov, B. 2017-08-01 In this work we review substorms, originated during the 2014/2015 winter season. Observations of the Multiscale Aurora Imaging Network (MAIN) in Apatity have been used. Solar wind and interplanetary magnetic field parameters were estimated by the 1-min sampled OMNI data base from CDAWeb (http://cdaweb.gsfc.nasa.gov/cdaweb/ istp_public/). Auroral disturbances were verified by the 10-s sampled data of IMAGE magnetometers and by data of the all-sky camera at Apatity. Subject of the review were the peculiarities in the development of substorms occurred during different geomagnetic conditions. The behavior of the substorms developed in non-storm time and during different phases of geomagnetic storms was discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850054398&hterms=Earth+space&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEarth%2Bspace','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850054398&hterms=Earth+space&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEarth%2Bspace">The ionospheric contribution to the plasma environment in near-earth space</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Sharp, R. D.; Lennartsson, W.; Strangeway, R. J. 1985-01-01 SCATHA and ISEE 1 satellite ion mass spectrometer data on ion composition near GEO are reviewed. The data were gathered during and close to magnetic storm activity to assess the characteristics of ion composition variations in order to predict the effects of hot GEO plasma on spacecraft instruments. Attention is given to both substorms and storms, the former being associated, at high latitudes, with auroral activity, the latter with ring currents. The ionosphere was found to supply hot H(+), O(+) and He(+) ions to the GEO magnetosphere, while the solar wind carried H(+) and He(+) ions. The ionosphere was the dominant source in both quiet and storm conditions in the inner magnetosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..4411217Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..4411217Y">Mechanisms of Saturn's Near-Noon Transient Aurora: In Situ Evidence From Cassini Measurements</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Yao, Z. H.; Radioti, A.; Rae, I. J.; Liu, J.; Grodent, D.; Ray, L. C.; Badman, S. V.; Coates, A. J.; Gérard, J.-C.; Waite, J. H.; Yates, J. N.; Shi, Q. Q.; Wei, Y.; Bonfond, B.; Dougherty, M. K.; Roussos, E.; Sergis, N.; Palmaerts, B. 2017-11-01 Although auroral emissions at giant planets have been observed for decades, the physical mechanisms of aurorae at giant planets remain unclear. One key reason is the lack of simultaneous measurements in the magnetosphere while remote sensing of the aurora. We report a dynamic auroral event identified with the Cassini Ultraviolet Imaging Spectrograph (UVIS) at Saturn on 13 July 2008 with coordinated measurements of the magnetic field and plasma in the magnetosphere. The auroral intensification was transient, only lasting for ˜30 min. The magnetic field and plasma are perturbed during the auroral intensification period. We suggest that this intensification was caused by wave mode conversion generated field-aligned currents, and we propose two potential mechanisms for the generation of this plasma wave and the transient auroral intensification. A survey of the Cassini UVIS database reveals that this type of transient auroral intensification is very common (10/11 time sequences, and ˜10% of the total images). </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970027994','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970027994">Observations of Thermospheric Horizontal Winds at Watson Lake, Yukon Territory (lambda=65 Deg N)</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Niciejewski, R. J.; Killeen, T. L.; Solomon, Stanley C. 1996-01-01 Fabry-Perot interferometer observations of the thermospheric O I (6300 A) emission have been conducted from an airglow observatory at a dark field site in the southeastern Yukon Territory, Canada, for the period November 1991 to April 1993. The experiment operated in unattended, remote fashion, has resulted in a substantial data set from which mean neutral winds have been determined. Dependent upon geomagnetic activity, the nocturnal location of the site is either equatorward of the auroral oval or within oval boundaries. The data set is rich enough to permit hourly binning of neutral winds based upon the K(sub p) geomagnetic disturbance index as well as the season. For cases of low geomagnetic activity the averaged vector horizontal neutral wind exhibits the characteristics of a midlatitude site displaying antisunward pressure-gradient-driven winds. As the geomagnetic activity rises in the late afternoon and evening winds slowly rotate sunward in an anticlockwise direction, initially remaining near 100 m/s in speed but eventually increasing to 300 m/s for K(sub p) greater than 5. For the higher levels of activity the observed neutral wind flow pattern resembles a higher-latitude polar cap pattern characterized by ion drag forcing of thermospheric neutral gases. In addition, rotational Coriolis forcing on the dusk side enhances the ion drag forcing, resulting in dusk winds which trace out the clockwise dusk cell plasma flow. On the dawn side the neutral winds also rotate in an anticlockwise direction as the strength of geomagnetic disturbances increase. Since the site is located at a transition latitude between the midlatitude and the polar cap the data set provides a sensitive test for general circulation models which attempt to parameterize the contribution of magnetospheric processes. A comparison with the Vector Spherical Harmonic (VSH) model indicates several regions of poor correspondence for December solstice conditions but reasonable agreement for the vernal equinox. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940031914','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940031914">Theoretical and experimental studies relevant to interpretation of auroral emissions</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Keffer, Charles E. 1994-01-01 This report describes the accomplishments of a program designed to develop the tools necessary to interpret auroral emissions measured from a space-based platform. The research was divided into two major areas. The first area was a laboratory study designed to improve our understanding of the space vehicle external environment and how it will affect the space-based measurement of auroral emissions. Facilities have been setup and measurements taken to simulate the gas phase environment around a space vehicle; the radiation environment encountered by an orbiting vehicle that passes through the Earth's radiation belts; and the thermal environment of a vehicle in Earth orbit. The second major area of study was a modeling program to develop the capability of using auroral images at various wavelengths to infer the total energy influx and characteristic energy of the incident auroral particles. An ab initio auroral calculation has been added to the extant ionospheric/thermospheric global modeling capabilities within our group. Once the addition of the code was complete, the combined model was used to compare the relative intensities and behavior of various emission sources (dayglow, aurora, etc.). Attached papers included are: 'Laboratory Facility for Simulation of Vehicle-Environment Interactions'; 'Workshop on the Induced Environment of Space Station Freedom'; 'Radiation Damage Effects in Far Ultraviolet Filters and Substrates'; 'Radiation Damage Effects in Far Ultraviolet Filters, Thin Films, and Substrates'; 'Use of FUV Auroral Emissions as Diagnostic Indicators'; and 'Determination of Ionospheric Conductivities from FUV Auroral Emissions'. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Ge%26Ae..58...70Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Ge%26Ae..58...70Z">Features of High-Latitude Ionospheric Irregularities Development as Revealed by Ground-Based GPS Observations, Satellite-Borne GPS Observations and Satellite In Situ Measurements over the Territory of Russia during the Geomagnetic Storm on March 17-18, 2015</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Zakharenkova, I. E.; Cherniak, Iu. V.; Shagimuratov, I. I.; Klimenko, M. V. 2018-01-01 The dynamic picture of the response of the high- and mid-latitude ionosphere to the strong geomagnetic disturbances on March 17-18, 2015, has been studied with ground-based and satellite observations, mainly, by transionospheric measurements of delays of GPS (Global Positioning System) signals. The advantages of the joint use of ground-based GPS measurements and GPS measurements on board of the Swarm Low-Earth-Orbit satellite mission for monitoring of the appearance of ionospheric irregularities over the territory of Russia are shown for the first time. The results of analysis of ground-based and space-borne GPS observations, as well as satellite, in situ measurements, revealed large-scale ionospheric plasma irregularities observed over the territory of Russia in the latitude range of 50°-85° N during the main phase of the geomagnetic storm. The most intense ionospheric irregularities were detected in the auroral zone and in the region of the main ionospheric trough (MIT). It has been found that sharp changes in the phase of the carrier frequency of the navigation signal from all tracked satellites were recorded at all GPS stations located to the North from 55° MLAT. The development of a deep MIT was related to dynamic processes in the subauroral ionosphere, in particular, with electric fields of the intense subauroral polarization stream. Analysis of the electron and ion density values obtained by instruments on board of the Swarm and DMSP satellites showed that the zone of highly structured auroral ionosphere extended at least to heights of 850-900 km. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/484523','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/484523"></a> <a target="_blank" rel="noopener noreferrer" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a> Yukhimuk, V.; Roussel-Dupre, R. In this paper the evolution of nonlinear scattering of whistler mode waves by kinetic Alfven waves (KAW) in time and two spatial dimensions is studied analytically. The authors suggest this nonlinear process as a mechanism of kinetic Alfven wave generation in space plasmas. This mechanism can explain the dependence of Alfven wave generation on whistler waves observed in magnetospheric and ionospheric plasmas. The observational data show a dependence for the generation of long periodic pulsations Pc5 on whistler wave excitation in the auroral and subauroral zone of the magnetosphere. This dependence was first observed by Ondoh T.I. For 79 casesmore » of VLF wave excitation registered by Ondoh at College Observatory (L=64.6 N), 52 of them were followed by Pc5 geomagnetic pulsation generation. Similar results were obtained at the Loparskaia Observatory (L=64 N) for auroral and subauroral zone of the magnetosphere. Thus, in 95% of the cases when VLF wave excitation occurred the generation of long periodic geomagnetic pulsations Pc5 were observed. The observations also show that geomagnetic pulsations Pc5 are excited simultaneously or insignificantly later than VLF waves. In fact these two phenomena are associated genetically: the excitation of VLF waves leads to the generation of geomagnetic pulsations Pc5. The observations show intensive generation of geomagnetic pulsations during thunderstorms. Using an electromagnetic noise monitoring system covering the ULF range (0.01-10 Hz) A.S. Fraser-Smith observed intensive ULF electromagnetic wave during a large thunderstorm near the San-Francisco Bay area on September 23, 1990. According to this data the most significant amplification in ULF wave activity was observed for waves with a frequency of 0.01 Hz and it is entirely possible that stronger enhancements would have been measured at lower frequencies.« less </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active">22</li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active">23</li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720056314&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dconvection%2Bcurrents','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720056314&hterms=convection+currents&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dconvection%2Bcurrents">The Harang discontinuity in auroral belt ionospheric currents.</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Heppner, J. P. 1972-01-01 Discussion of the nature of a discontinuity in the ionospheric current of the auroral belt whose existence was suggested by Harang in 1946. Convection characteristics, time variability, and current continuity in the auroral belt are considered in a context of observations and arguments supporting the reality of Harang's discontinuity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...850..184C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...850..184C">The Crab Pulsar and Relativistic Wind</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Coroniti, F. V. 2017-12-01 The possibility that the Crab pulsar produces a separated ion-dominated and pair-plasma-dominated, magnetically striped relativistic wind is assessed by rough estimates of the polar cap acceleration of the ion and electron primary beams, the pair production of secondary electrons and positrons, and a simple model of the near-magnetosphere-wind zone. For simplicity, only the orthogonal rotator is considered. Below (above) the rotational equator, ions (electrons) are accelerated in a thin sheath, of order (much less than) the width of the polar cap, to Lorentz factor {γ }i≈ (5{--}10)× {10}7({γ }e≈ {10}7). The accelerating parallel electric field is shorted out by ion-photon (curvature synchrotron) pair production. With strong, but fairly reasonable, assumptions, a set of general magnetic geometry relativistic wind equations is derived and shown to reduce to conservation relations that are similar to those of the wind from a magnetic monopole. The strength of the field-aligned currents carried by the primary beams is determined by the wind’s Alfvén critical point condition to be about eight times the Goldreich-Julian value. A simple model for the transition from the dipole region wind to the asymptotic monopole wind zone is developed. The asymptotic ratio of Poynting flux to ion (pair plasma) kinetic energy flux—the wind {σ }w∞ -parameter—is found to be of order {σ }w∞ ≈ 1/2({10}4). The far wind zone is likely to be complex, with the ion-dominated and pair-plasma-dominated magnetic stripes merging, and the oppositely directed azimuthal magnetic fields annihilating. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870036449&hterms=coastal+zone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dcoastal%2Bzone','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870036449&hterms=coastal+zone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dcoastal%2Bzone">Wind effects on coastal zone color scanner chlorophyll patterns in the U.S. Mid-Atlantic Bight during spring 1979</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Eslinger, David L.; Iverson, Richard L. 1986-01-01 Coastal zone color scanner (CZCS) chlorophyll concentration increases in the Mid-Atlantic Bight were associated with high wind speeds in continental shelf waters during March and May 1979. Maximum spring CZCS chlorophyll concentrations occurred during April when the water column was not thermally stratified and were spatially and temporally associated with reductions in wind speed both in onshelf and in offshelf regions. Increased chlorophyll concentrations in offshelf waters were associated with high wind speeds during May when a deep chlorophyll maximum was present. Chlorophyll patchiness was observed on length scales typical of those controlled by biological processes during the April low-wind period but not during March or May when wind speeds were greater. The spring CZCS chlorophyll maximum in the southern portion of the Mid-Atlantic Bight occurred in response to a reduction in mixed layer depth caused by decreased wind speeds and not by increased water column stratification. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.U22A..03M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.U22A..03M">First Results from the Jupiter Energetic Particle Detector Instrument (JEDI) Investigation Within the Magnetosphere and Over the Poles of Jupiter</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Mauk, B.; Haggerty, D. K.; Paranicas, C.; Clark, G. B.; Kollmann, P.; Rymer, A. M.; Brown, L. E.; Jaskulek, S. E.; Schlemm, C. E.; Kim, C. K.; Nelson, K.; Bolton, S. J.; Bagenal, F.; Connerney, J. E. P.; Gladstone, R.; Kurth, W. S.; Levin, S.; McComas, D. J.; Valek, P. W. 2016-12-01 The Juno spacecraft first entered Jupiter's magnetosphere on 25 June 2016, but evidence for Jupiter's magnetospheric environment was first observed by the Jupiter Energetic Particle Detector Instrument (JEDI) as early as January 2016 in the form of leaking energetic particles observed over 1200 RJ away from Jupiter. JEDI is an energetic particle instrument designed to measure the energy, angular, and compositional distribution of energetic electrons ( 25 to > 700 keV) and ions (protons: 10 keV to > 1.5 MeV). A special set of channels for oxygen and sulfur extend up in energy to > 10 MeV. The JEDI instrument comprises three separate sensor heads, each with multiple (6) telescopes, in order to capture angular distributions of energetic particles over the poles of Jupiter as Juno rushes over auroral forms as narrow as < 80 km at a speed of up to 55 km/s. Since entering Jupiter's magnetosphere JEDI has observed both familiar, and some unfamiliar structures, including: 1) undulations along the dawn flank of Jupiter's magnetosphere possibly signaling the occurrence of Kelvin-Helmholz instability structures thought to play a role in coupling the solar wind energetics to the dynamics of Jupiter's magnetosphere, and 2) spiky electron transients with magnetic field-aligned angular distributions within the distant magnetodisc plasmas conjectured to be related to transient auroral forms observed at other times by the Hubble Space Telescope poleward of Jupiter's main aurora. A principal target of JEDI and other fields and particles instruments on Juno is the near-planet polar regions of Jupiter's space environment, never-before visited by spacecraft. These instruments were designed to determine the physics of auroral acceleration at Jupiter and the role that those processes play in enabling Jupiter to spin up and energize its vast magnetospheric space environment. The first polar pass is scheduled for 27 August 2016. In this report we present the first results from the JEDI instrument after making measurements in this novel polar environment. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P31C2825D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P31C2825D">Chandra observations of Jupiter's X-ray Aurora during Juno upstream and apojove intervals</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Dunn, W.; Jackman, C. M.; Kraft, R.; Gladstone, R.; Branduardi-Raymont, G.; Knigge, C.; Altamirano, D.; Elsner, R.; Kammer, J. 2017-12-01 The Chandra space telescope has recently conducted a number of campaigns to observe Jupiter's X-ray aurora. The first set of campaigns took place in summer 2016 while the Juno spacecraft was upstream of the planet sampling the solar wind. The second set of campaigns took place in February, June and August 2017 at times when the Juno spacecraft was at apojove. These campaigns were planned following the Juno orbit correction to capitalise on the opportunity to image the X-ray emission while Juno was orbiting close to the expected position of the magnetopause. Previous work has suggested that the auroral X-ray emissions map close to the magnetopause boundary [e.g. Vogt et al., 2015; Kimura et al., 2016; Dunn et al., 2016] and thus in situ spacecraft coverage in this region combined with remote observation of the X-rays afford the chance to constrain the drivers of these energetic emissions and determine if they originate on open or closed field lines. We aim to examine possible drivers of X-ray emission including reconnection and the Kelvin-Helmholtz instability and to explore the role of the solar wind in controlling the emissions. We report on these upstream and apojove campaigns including intensities and periodicities of auroral X-ray emissions. This new era of jovian X-ray astronomy means we have more data than ever before, long observing windows (up to 72 ks for this Chandra set), and successive observations relatively closely spaced in time. These features combine to allow us to pursue novel methods for examining periodicities in the X-ray emission. Our work will explore significance testing of emerging periodicities, and the search for coherence in X-ray pulsing over weeks and months, seeking to understand the robustness and regularity of previously reported hot spot X-ray emissions. The periods that emerge from our analysis will be compared against those which emerge from radio and UV wavelengths. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRA..123.2974O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRA..123.2974O">Modeling Study of the Geospace System Response to the Solar Wind Dynamic Pressure Enhancement on 17 March 2015</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Ozturk, D. S.; Zou, S.; Ridley, A. J.; Slavin, J. A. 2018-04-01 The global magnetosphere-ionosphere-thermosphere system is intrinsically coupled and susceptible to external drivers such as solar wind dynamic pressure enhancements. In order to understand the large-scale dynamic processes in the magnetosphere-ionosphere-thermosphere system due to the compression from the solar wind, the 17 March 2015 sudden commencement was studied in detail using global numerical models. This storm was one of the most geoeffective events of the solar cycle 24 with a minimum Dst of -222 nT. The Wind spacecraft recorded a 10-nPa increment in the solar wind dynamic pressure, while the interplanetary magnetic field BZ became further northward. The University of Michigan Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme global magnetohydrodynamic code was utilized to study the generation and propagation of perturbations associated with the compression of the magnetosphere system. In addition, the high-resolution electric potential and auroral power output from the magnetohydrodynamic model was used to drive the global ionosphere-thermosphere model to investigate the ionosphere-thermosphere system response to pressure enhancement. During the compression, the electric potentials and convection patterns in the polar ionosphere were significantly altered when the preliminary impulse and main impulse field-aligned currents moved from dayside to nightside. As a result of enhanced frictional heating, plasma and neutral temperatures increased at the locations where the flow speeds were enhanced, whereas the electron density dropped at these locations. In particular, the region between the preliminary impulse and main impulse field-aligned currents experienced the most significant heating with 1000-K ion temperature increase and 20-K neutral temperature increase within 2 min. Comparison of the simulation results with the Poker Flat Incoherent Scatter Radar observations showed reasonable agreements despite underestimated magnitudes. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940030852','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940030852">Analytic model of aurorally coupled magnetospheric and ionospheric electrostatic potentials</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Cornwall, J. M. 1994-01-01 This paper describes modest but significant improvements on earlier studies of electrostatic potential structure in the auroral region using the adiabatic auroral arc model. This model has crucial nonlinearities (connected, for example. with aurorally produced ionization) which have hampered analysis; earlier work has either been linear, which I will show is a poor approximation or, if nonlinear, either numerical or too specialized to study parametric dependencies. With certain simplifying assumptions I find new analytic nonlinear solutions fully exhibiting the parametric dependence of potentials on magnetospheric (e.g.. cross-tail potential) and ionospheric (e.g., recombination rate) parameters. No purely phenomenological parameters are introduced. The results are in reasonable agreement with observed average auroral potential drops, inverted-V scale sizes, and dissipation rates. The dissipation rate is quite comparable to tail energization and transport rates and should have a major effect on tail and magnetospheric dynamics. This paper gives various relations between the cross-tail potential and auroral parameters (e.g., total parallel currents and potential drops) which can be studied with existing data sets. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..4410162L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..4410162L">Understanding the Origin of Jupiter's Diffuse Aurora Using Juno's First Perijove Observations</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Li, W.; Thorne, R. M.; Ma, Q.; Zhang, X.-J.; Gladstone, G. R.; Hue, V.; Valek, P. W.; Allegrini, F.; Mauk, B. H.; Clark, G.; Kurth, W. S.; Hospodarsky, G. B.; Connerney, J. E. P.; Bolton, S. J. 2017-10-01 Juno observed the low-altitude polar region during perijove 1 on 27 August 2016 for the first time. Auroral intensity and false-color maps from the Ultraviolet Spectrograph (UVS) instrument show extensive diffuse aurora observed equatorward of the main auroral oval. Juno passed over the diffuse auroral region near the System III longitude of 120°-150° (90°-120°) in the northern (southern) hemisphere. In the region where these diffuse auroral emissions were observed, the Jupiter Energetic Particle Detector Instrument (JEDI) and Jovian Auroral Distributions Experiment (JADE) instruments measured nearly full loss cone distributions for the downward going electrons over energies of 0.1-700 keV but very few upward going electrons. The false-color maps from UVS indicate more energetic electron precipitation at lower latitudes than less energetic electron precipitation, consistent with observations of precipitating electrons measured by JEDI and JADE. The comparison between particle and aurora measurements provides first direct evidence that these precipitating energetic electrons are mainly responsible for the diffuse auroral emissions at Jupiter. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23312860','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23312860">Epifauna dynamics at an offshore foundation--implications of future wind power farming in the North Sea.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Krone, Roland; Gutow, Lars; Joschko, Tanja J; Schröder, Alexander 2013-04-01 In the light of the introduction of thousands of large offshore wind power foundations into the North Sea within the next decades, this manuscript focuses on the biofouling processes and likely reef effects. The study explores the macrozoobenthos (biofouling) colonization at an offshore platform which is comparable to offshore wind turbine foundations. A total of 183 single samples were taken and the parameters water depth and time were considered comparing biofouling masses and communities. The blue mussel Mytilus edulis, Anthozoa and the Amphipoda Jassa spp. were the dominant species. The community from the 1 m zone and those from the 5 and 20-28 m zones can clearly be differentiated. The 10 m zone community represents the transition between the M. edulis dominated 1 m and 5 m zones and the Anthozoa dominated 20-28 m zone. In the future offshore wind farms, thousands of wind turbine foundations will provide habitat for a hard bottom fauna which is otherwise restricted to the sparse rocky habitats scattered within extensive sedimentary soft bottoms of the German Bight. However, offshore wind power foundations cannot be considered natural rock equivalents as they selectively increase certain natural hard bottom species. The surface of the construction (1280 m²) was covered by an average of 4300 kg biomass. This foundation concentrates on its footprint area (1024 m²) 35 times more macrozoobenthos biomass than the same area of soft bottom in the German exclusive economic zone (0.12 kg m(-2)), functioning as a biomass hotspot. Concerning the temporal biomass variation, we assume that at least 2700 kg biomass was exported on a yearly basis. 345 × 10(4) single mussel shells of different sizes were produced during the study period. It is anticipated that the M. edulis abundance will increase in the North Sea due to the expansion of the offshore wind farm development. This will result in the enhanced production of secondary hard substrate (mussel shells) and its associated fauna and will intensify filtration rates of the seawater. This predicted ecological system change is coined the 'Mytilusation' of the German Bight. Copyright © 2012 Elsevier Ltd. All rights reserved. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-07-20/pdf/2011-18300.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-07-20/pdf/2011-18300.pdf">76 FR 43260 - Foreign-Trade Zone 72-Indianapolis, IN; Application for Temporary/Interim Manufacturing Authority...</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a> 2011-07-20 ...--Indianapolis, IN; Application for Temporary/Interim Manufacturing Authority; Brevini Wind USA, Inc. (Wind... temporary/interim manufacturing (T/IM) authority within FTZ 72 at the Brevini Wind USA, Inc. (Brevini... requested authority to produce wind turbine gear boxes (HTSUS 8483.40, duty rate: 2.5%). Foreign components... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol6/pdf/CFR-2012-title40-vol6-sec53-43.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol6/pdf/CFR-2012-title40-vol6-sec53-43.pdf">40 CFR 53.43 - Test procedures.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a> 2012-07-01 ... of the test section of the wind tunnel. The mean wind speed in the test section must be within ±10... wind tunnel and allow the particle concentration to stabilize. (vi) Install an array of five or more evenly spaced isokinetic samplers in the sampling zone (see § 53.42(d)) of the wind tunnel. Collect... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol6/pdf/CFR-2014-title40-vol6-sec53-43.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol6/pdf/CFR-2014-title40-vol6-sec53-43.pdf">40 CFR 53.43 - Test procedures.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a> 2014-07-01 ...-sectional area of the test section of the wind tunnel. The mean wind speed in the test section must be... into the wind tunnel and allow the particle concentration to stabilize. (vi) Install an array of five or more evenly spaced isokinetic samplers in the sampling zone (see § 53.42(d)) of the wind tunnel... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol6/pdf/CFR-2013-title40-vol6-sec53-43.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol6/pdf/CFR-2013-title40-vol6-sec53-43.pdf">40 CFR 53.43 - Test procedures.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a> 2013-07-01 ...-sectional area of the test section of the wind tunnel. The mean wind speed in the test section must be... into the wind tunnel and allow the particle concentration to stabilize. (vi) Install an array of five or more evenly spaced isokinetic samplers in the sampling zone (see § 53.42(d)) of the wind tunnel... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730023014','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730023014">Wind tunnel studies of Martian aeolian processes</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Greeley, R.; Iversen, J. D.; Pollack, J. B.; Udovich, N.; White, B. 1973-01-01 Preliminary results are reported of an investigation which involves wind tunnel simulations, geologic field studies, theoretical model studies, and analyses of Mariner 9 imagery. Threshold speed experiments were conducted for particles ranging in specific gravity from 1.3 to 11.35 and diameter from 10.2 micron to 1290 micron to verify and better define Bagnold's (1941) expressions for grain movement, particularly for low particle Reynolds numbers and to study the effects of aerodynamic lift and surface roughness. Wind tunnel simulations were conducted to determine the flow field over raised rim craters and associated zones of deposition and erosion. A horseshoe vortex forms around the crater, resulting in two axial velocity maxima in the lee of the crater which cause a zone of preferential erosion in the wake of the crater. Reverse flow direction occurs on the floor of the crater. The result is a distinct pattern of erosion and deposition which is similar to some martian craters and which indicates that some dark zones around Martian craters are erosional and some light zones are depositional. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.2970S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.2970S">Experimental investigation of change of energy of infragavity waves in dependence on spectral characteristics of an irregular wind waves in coastal zone</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Saprykina, Yana; Divinskii, Boris 2013-04-01 An infragravity waves are long waves with periods of 20 - 300 s. Most essential influence of infragarvity waves on dynamic processes is in a coastal zone, where its energy can exceed the energy of wind waves. From practical point of view, the infragravity waves are important, firstly, due to their influence on sand transport processes in a coastal zone. For example, interacting with group structure of wind waves the infragravity waves can define position of underwater bars on sandy coast. Secondly, they are responsible on formation of long waves in harbors. Main source of infragravity waves is wave group structure defined by sub-nonlinear interactions of wind waves (Longuet-Higgins, Stewart, 1962). These infragravity waves are bound with groups of wind waves and propagate with wave group velocity. Another type of infragravity waves are formed in a surf zone as a result of migration a wave breaking point (Symonds, et al., 1982). What from described above mechanisms of formation of infragravity waves prevails, till now it is unknown. It is also unknown how energy of infragravity waves depends on energy of input wind waves and how it changes during nonlinear wave transformation in coastal zone. In our work on the basis of the analysis of data of field experiment and numerical simulation a contribution of infragravity waves in total wave energy in depending on integral characteristics of an irregular wave field in the conditions of a real bathymetry was investigated. For analysis the data of field experiment "Shkorpilovtsy-2007" (Black sea) and data of numerical modeling of Boussinesq type equation with extended dispersion characteristics (Madsen et al., 1997) were used. It was revealed that infragravity waves in a coastal zone are defined mainly by local group structure of waves, which permanently changes due to nonlinearity, shoaling and breaking processes. Free infragravity waves appearing after wave breaking exist together with bound infragravity waves. There are no clear total dependences of energy of infrragravity waves from energy of wind waves and mean period of infragravity waves from mean period of wind waves. But significant wave height of infragravity waves depends on relative water depth (wave height of wind waves divided on water depth). There are different types of this dependence for breaking and non-breaking waves. The influence of peak period, significant wave height and directional spreading of initial wave spectrum on these dependences are discussed. The peculiarities of spectra of infragravity waves for non-breaking, breaking and multibreaking wind waves are shown. This work is supported by the RFBR, project 12-05-00965. References: Longuet-Higgins, M. S., R. W. Stewart, 1962. Radiation stress and mass transport in gravity waves, with an application to surf beats. J. Fluid Mech., 13, pp. 481-504. Symonds G., D.A. Huntley, A.J. Bowen, 1982. Two dimensional surf beat: long wave generation by a time-varying breakpoint. J. of Geoph. Res., 87(C), pp.492-498. Madsen P.A., Sorensen O.R., Shaffer H.A. 1997. Surf zone dynamics simulated by a Boussinesq type model. Coastal Engineering, 32, p. 255-287. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://eosweb.larc.nasa.gov/project/polarwindsii/polarwindsii_table','SCIGOV-ASDC'); return false;" href="https://eosweb.larc.nasa.gov/project/polarwindsii/polarwindsii_table">PolarWinds I & II</a> <a target="_blank" rel="noopener noreferrer" href="http://eosweb.larc.nasa.gov/">Atmospheric Science Data Center </a> 2018-04-20 ... (Organized Large Eddies), and near surface winds over open water, transitional ice zones and the Greenland Ice Cap. Polar Winds I was ... total, twenty-four individual missions with over 80 hours of research flights were flown in the Arctic region near Greenland and Iceland ... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790052142&hterms=History+Wave+Energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHistory%2BWave%2BEnergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790052142&hterms=History+Wave+Energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DHistory%2BWave%2BEnergy">Auroral origin of medium scale gravity waves in neutral composition and temperature</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chandra, S.; Spencer, N. W.; Krankowsky, D.; Laemmerzahl, P. 1979-01-01 The kinetic temperature and neutral composition data obtained from the Aeros B neutral atmosphere temperature experiment and the neutral and ion mass spectrometer show spatial structures characteristic of medium scale gravity waves with a wavelength in the range of several hundred kilometers. These waves are associated with auroral activity, and their spatial structure reflects the time history of the auroral electrojet. The medium scale gravity waves tend to propagate to mid-latitudes on the nightside. On the dayside their range is limited to high latitudes. Gravity waves are carriers of auroral energy to middle and low latitudes where they may cause irreversible changes in temperature via viscous dissipation. Since auroral activity occurs frequently, it is suggested that this energy reaches the mid-latitude region of the thermosphere much more frequently than is indicated by planetary magnetic indices. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840034545&hterms=attention+pictures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dattention%2Bpictures','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840034545&hterms=attention+pictures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dattention%2Bpictures">Auroral photometry from the atmosphere Explorer satellite</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Rees, M. H.; Abreu, V. J. 1984-01-01 Attention is given to the ability of remote sensing from space to yield quantitative auroral and ionospheric parametrers, in view of the auroral measurements made during two passes of the Explorer C satellite over the Poker Flat Optical Observatory and the Chatanika Radar Facility. The emission rate of the N2(+) 4278 A band computed from intensity measurements of energetic auroral electrons has tracked the same spetral feature that was measured remotely from the satellite over two decades of intensity, providing a stringent test for the measurement of atmospheric scattering effects. It also verifies the absolute intensity with respect to ground-based photometric measurements. In situ satellite measurments of ion densities and ground based electron density profile radar measurements provide a consistent picture of the ionospheric response to auroral input, while also predicting the observed optical emission rate. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMSM31B0319S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMSM31B0319S">Observation of hectometric auroral radio emissions in Iceland</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Sato, Y.; Ono, T.; Iizima, M.; Sato, N. 2006-12-01 The Earth's auroral region is an active radio source at frequencies from a few hertz to several megahertz. In the hectometric range, it was found that Terrestrial Hectometric Radiation (THR) is related to auroras by observations of the Ohzora satellite [Oya et al.(1985)]. In resent research, Shinbori et al. [2003] showed that occurrence of THR follows SC by several minutes using the Akebono satellite data. On the ground, auroral roar and MF burst were discovered by Kellogg and Monson [1979, 1984] and Weatherwax et al. [1994] in the northern Canada, respectively. Because there is not enough physical and geophysical characterization of these radio emissions, the physical mechanism of these phenomena in the auroral ionosphere has not been fully understood yet. We set up new observation system at Husafell station in Iceland in September, 2005 and have started to observe auroral radio emissions. Radio signals, which are received by the cross loop antennas, are converted into left- and right- handed polarized components within the frequency range from 1 MHz to 5 MHz. Based on the calibration of system, it was found that the possibility of occurence would be smaller than expected due to the low sensitivity because average power spectrum densities of auroral roar and MF burst are 50-100 nV/m/Hz^1/2. So, the system was planed to be upgraded in this September, which makes it possible to detect auroral roar and MF burst. It is expected that the detail physical process will be elucidated by clarifying the spectrum, polarization, dependence on the geomagnetic activity, and so on. In this presentation, we will show the improved points of the new system and preliminary observation results. There is a basic question whether auroral roar and MF burst observed on the ground are generated by the same process as THR observed by satellites. By comparing the results from the ground-based observation and the Akebono satellite observation of THR, it becomes possible to obtain a new picture of auroral radio emissions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSM23A2536H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSM23A2536H">Evolution of auroral acceleration region field-aligned current systems, plasma, and potentials observed by Cluster during substorms</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hull, A. J.; Chaston, C. C.; Fillingim, M. O.; Frey, H. U.; Goldstein, M. L.; Bonnell, J. W.; Mozer, F. 2015-12-01 The auroral acceleration region is an integral link in the chain of events that transpire during substorms, and the currents, plasma and electric fields undergo significant changes driven by complex dynamical processes deep in the magnetotail. The acceleration processes that occur therein accelerate and heat the plasma that ultimately leads to some of the most intense global substorm auroral displays. Though this region has garnered considerable attention, the temporal evolution of field-aligned current systems, associated acceleration processes, and resultant changes in the plasma constituents that occur during key stages of substorm development remain unclear. In this study we present a survey of Cluster traversals within and just above the auroral acceleration region (≤3 Re altitude) during substorms. Particular emphasis is on the spatial morphology and developmental sequence of auroral acceleration current systems, potentials and plasma constituents, with the aim of identifying controlling factors, and assessing auroral emmission consequences. Exploiting multi-point measurements from Cluster in combination with auroral imaging, we reveal the injection powered, Alfvenic nature of both the substorm onset and expansion of auroral particle acceleration. We show evidence that indicates substorm onsets are characterized by the gross-intensification and filamentation/striation of pre-existing large-scale current systems to smaller/dispersive scale Alfven waves. Such an evolutionary sequence has been suggested in theoretical models or single spacecraft data, but has not been demonstrated or characterized in multispacecraft observations until now. It is also shown how the Alfvenic variations over time may dissipate to form large-scale inverted-V structures characteristic of the quasi-static aurora. These findings suggest that, in addition to playing active roles in driving substorm aurora, inverted-V and Alfvenic acceleration processes are causally linked. Key elements of substorm current spatial structure and temporal development, relationship to electric fields/potentials, plasma moment and distribution features, causal linkages to auroral emission features, and other properties will be discussed. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active">23</li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active">24</li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780048772&hterms=geomagnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgeomagnetism','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780048772&hterms=geomagnetism&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgeomagnetism">The Third General Scientific Assembly of the International Association of Geomagnetism and Aeronomy - Special sessions of auroral processes</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Russell, C. T. 1978-01-01 Methods of timing magnetic substorms, the rapid fluctuations of aurorae, electromagnetic and electrostatic instabilities observed on the field lines of aurorae, the auroral microstructure, and the relationship of currents, electric field and particle precipitation to auroral form are discussed. Attention is given to such topics as D-perturbations as an indicator of substorm onset, the role of the magnetotail in substorms, spectral information derived from imaging data on aurorae, terrestrial kilometric radiation, and the importance of the mirror force in self-consistent models of particle fluxes, currents and potentials on auroral field lines. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910025795&hterms=discrete+structure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddiscrete%2Bstructure','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910025795&hterms=discrete+structure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Ddiscrete%2Bstructure">A mathematical model of the structure and evolution of small-scale discrete auroral arcs</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Seyler, Charles E. 1990-01-01 A three-dimensional fluid model for the structure and evolution of small-scale discrete auroral arcs originating from Alfven waves is developed and used to study the nonlinear macroscopic plasma dynamics of these auroral arcs. The results of simulations show that stationary auroral arcs can be unstable to a collisionless tearing mode which may be responsible for the observed transverse structuring in the form of folds and curls. At late times, the plasma becomes turbulent having transverse electric field power spectra that tend toward a universal k exp -5/3 spectral form. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750050946&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnike','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750050946&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dnike">Electron currents associated with an auroral band</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Spiger, R. J.; Anderson, H. R. 1975-01-01 Measurements of electron pitch angle distributions and energy spectra over a broad auroral band were used to calculate net electric current carried by auroral electrons in the vicinity of the band. The particle energy spectrometers were carried by a Nike-Tomahawk rocket launched from Poker Flat, Alaska, at 0722 UT on February 25, 1972. Data are presented which indicate the existence of upward field-aligned currents of electrons in the energy range 0.5-20 keV. The spatial relationship of these currents to visual structure of the auroral arc and the characteristics of the electrons carrying the currents are discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMED43C3488M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMED43C3488M">Visualizing Space Weather: The Planeterrella Auroral Simulator as a Heliophysics Public Outreach Tool</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Masongsong, E. V.; Lilensten, J.; Booth, M. J.; Suri, G.; Heflinger, T. G.; Angelopoulos, V. 2014-12-01 The NASA THEMIS and ARTEMIS satellite missions study "space weather," which describes the solar wind influence on Earth's protective magnetic shield, the magnetosphere. Space weather is important to study and predict because it can damage critical GPS and communications satellites, harm space travelers, and even disable our global electrical grid. The Planeterrella is an innovative heliophysics outreach demonstration, expanding public awareness of space weather by visualizing the sun-Earth connection up close and in-person. Using a glass vacuum chamber, two magnetized spheres and a 1kV power supply, the device can simulate plasma configurations of the solar corona, solar wind, Van Allen radiation belts, and auroral ovals, all of which are observable only by satellites. This "aurora in a bottle" is a modernized version of the original Terrella built by Kristian Birkeland in the 1890s to show that the aurora are electrical in nature. Adapted from plans by Lilensten et al. at CNRS-IPAG, the UCLA Planeterrella was completed in Nov. 2013, the second device of its kind in the U.S., and the centerpiece of the THEMIS/ARTEMIS mobile public outreach exhibit. In combination with captivating posters, 3D magnetic field models, dazzling aurora videos and magnetosphere animations, the Planeterrella has already introduced over 1200 people to the electrical link between our sun and the planets. Most visitors had seen solar flare images in the news, however the Planeterrella experience enhanced their appreciation of the dynamic solar wind and its effects on Earth's invisible magnetic field. Most importantly, visitors young and old realized that magnets are not just cool toys or only for powering hybrid car motors and MRIs, they are a fundamental aspect of ongoing life on Earth and are key to the formation and evolution of planets, moons, and stars, extending far beyond our galaxy to other planetary systems throughout the universe. Novel visualizations such as the Planeterrella can significantly increase awareness of space weather and act as a catalyst for the pursuit of STEM careers by allowing students to form a personalized, emotional connection to the incredible phenomena surrounding our planet. This can translate into greater support for the heliophysics satellite infrastrucure that safeguards our modern society. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760007453','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760007453">Geomagnetic responses to the solar wind and the solar activity</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Svalgaard, L. 1975-01-01 Following some historical notes, the formation of the magnetosphere and the magnetospheric tail is discussed. The importance of electric fields is stressed and the magnetospheric convection of plasma and magnetic field lines under the influence of large-scale magnetospheric electric fields is outlined. Ionospheric electric fields and currents are intimately related to electric fields and currents in the magnetosphere and the strong coupling between the two regions is discussed. The energy input of the solar wind to the magnetosphere and upper atmosphere is discussed in terms of the reconnection model where interplanetary magnetic field lines merge or connect with the terrestrial field on the sunward side of the magnetosphere. The merged field lines are then stretched behind earth to form the magnetotail so that kinetic energy from the solar wind is converted into magnetic energy in the field lines in the tail. Localized collapses of the crosstail current, which is driven by the large-scale dawn/dusk electric field in the magnetosphere, divert part of this current along geomagnetic field lines to the ionosphere, causing substorms with auroral activity and magnetic disturbances. The collapses also inject plasma into the radiation belts and build up a ring current. Frequent collapses in rapid succession constitute the geomagnetic storm. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140009235','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140009235">Toward the Probabilistic Forecasting of High-latitude GPS Phase Scintillation</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Prikryl, P.; Jayachandran, P.T.; Mushini, S. C.; Richardson, I. G. 2012-01-01 The phase scintillation index was obtained from L1 GPS data collected with the Canadian High Arctic Ionospheric Network (CHAIN) during years of extended solar minimum 2008-2010. Phase scintillation occurs predominantly on the dayside in the cusp and in the nightside auroral oval. We set forth a probabilistic forecast method of phase scintillation in the cusp based on the arrival time of either solar wind corotating interaction regions (CIRs) or interplanetary coronal mass ejections (ICMEs). CIRs on the leading edge of high-speed streams (HSS) from coronal holes are known to cause recurrent geomagnetic and ionospheric disturbances that can be forecast one or several solar rotations in advance. Superposed epoch analysis of phase scintillation occurrence showed a sharp increase in scintillation occurrence just after the arrival of high-speed solar wind and a peak associated with weak to moderate CMEs during the solar minimum. Cumulative probability distribution functions for the phase scintillation occurrence in the cusp are obtained from statistical data for days before and after CIR and ICME arrivals. The probability curves are also specified for low and high (below and above median) values of various solar wind plasma parameters. The initial results are used to demonstrate a forecasting technique on two example periods of CIRs and ICMEs. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SunGe..12S...1A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SunGe..12S...1A">Recent Advances in Atmospheric, Solar-Terrestrial Physics and Space Weather From a North-South network of scientists [2006-2016] PART A: TUTORIAL</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Amory-Mazaudier, C.; Menvielle, M.; Curto, J-J.; Le Huy, M. 2017-12-01 This paper reviews scientific advances achieved by a North-South network between 2006 and 2016. These scientific advances concern Solar Terrestrial Physics, Atmospheric Physics and Space Weather. In this part A, we introduce knowledge on the Sun-Earth system. We consider the physical process of the dynamo which is present in the Sun, in the core of the Earth and also in the regions between the Sun and the Earth, the solar wind-magnetosphere and the ionosphere. Equations of plasma physics and Maxwell's equations will be recalled. In the Sun-Earth system there are permanent dynamos (Sun, Earth's core, solar wind - magnetosphere, neutral wind - ionosphere) and non-permanent dynamos that are activated during magnetic storms in the magnetosphere and in the ionosphere. All these dynamos have associated electric currents that affect the variations of the Earth's magnetic field which are easily measurable. That is why a part of the tutorial is also devoted to the magnetic indices which are indicators of the electric currents in the Sun-Earth system. In order to understand some results of the part B, we present some characteristics of the Equatorial region and of the electrodynamics coupling the Auroral and Equatorial regions. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940021701','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940021701">Dynamics explorer interdisciplinary scientist investigations</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Kozyra, Janet U.; Nagy, A. F. 1994-01-01 This document is a final report on research activities and accomplishments that occurred during the funding period of 10-1-90 through 1-30-94. The focus of our interdisciplinary investigation during the Dynamics Explorer Mission was on the complex coupling processes that tap the magnetic-storm energy, stored in the ring current particle reservoir, and transport this energy into the subauroral, midlatitude and even equatorial ionospheric regions. The transport of energy through the inner magnetosphere and into the underlying ionospheric regions is a critical element in our understanding of the impact of solar and magnetic disturbances on upper atmospheric and ionospheric regions equatorward of the auroral zone. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.1750L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.1750L">First results from the Blackstone HF radar in support of THEMIS</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lester, Mark; Greenwald, Raymond A.; Baker, Jo B. H.; Clauer, C. Robert; Grocott, Adrian; Milan, Steve E.; Yeoman, Timothy K.; Ruohoniemi, J. Michael A new HF radar has been constructed and built in Blackstone, VA as part of the Super- DARN/StormDARN programme specifically with the purpose of providing coverage over the Canadian ground sector in support of THEMIS. The new radar began operations in February 2008 an optimum time to support the first THEMIS tail campaign. This paper will discuss the importance of having radars at lower latitudes than the auroral zone locations of SuperDARN for substorm studies. Furthermore, the paper will also present the first results from this radar together with other SuperDARN observations during the THEMIS tail period. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMSM51B2486M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMSM51B2486M">A THEMIS Case Study of Pi2 Pulsations in the Magnetotail and on the Ground Before a Substorm Onset</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Miyashita, Y.; Angelopoulos, V.; Hiraki, Y.; Ieda, A.; Machida, S. 2016-12-01 Using THEMIS spacecraft and ground data, we studied low-frequency Pi2 pulsations in the magnetotail and on the ground just before a substorm onset. A case study shows that a new compressional Pi2 pulsation was observed in the plasma sheet just earthward of the near-Earth reconnection site 4 min before initial auroral brightening or 2 min before auroral fading. The ion and magnetic pressure perturbations appeared to be partly in phase at the beginning, indicating that the wave had fast mode. A similar wave was observed also tailward of the near-Earth reconnection site, although it occurred 4 min later. These waves may have been generated at the near-Earth reconnection site. On the ground, Pi2 pulsations were observed widely in the polar cap and at the auroral oval before initial auroral brightening and auroral fading, although the amplitudes were small, compared to those associated with auroral poleward expansion. There was a tendency that the waves were observed first in the polar cap near the initial auroral brightening site and then in the surrounding regions. Ionospheric convection began to be enhanced gradually 1 or 2 min after the Pi2 onsets. We discuss the causal relationship between the Pi2 pulsations in the magnetotail and on the ground as well as their role in substorm triggering. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70115060','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70115060">Centennial changes in North Pacific anoxia linked to tropical trade winds</a> <a target="_blank" rel="noopener noreferrer" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a> Deutsch, Curtis; Berelson, William; Thunell, Robert; Weber, Thomas; Tems, Caitlin; McManus, James; Crusius, John; Ito, Taka; Baumgartner, Timothy; Ferreira, Vicente; Mey, Jacob; van Geen, Alexander 2014-01-01 Climate warming is expected to reduce oxygen (O2) supply to the ocean and expand its oxygen minimum zones (OMZs). We reconstructed variations in the extent of North Pacific anoxia since 1850 using a geochemical proxy for denitrification (δ15N) from multiple sediment cores. Increasing δ15N since ~1990 records an expansion of anoxia, consistent with observed O2 trends. However, this was preceded by a longer declining δ15N trend that implies that the anoxic zone was shrinking for most of the 20th century. Both periods can be explained by changes in winds over the tropical Pacific that drive upwelling, biological productivity, and O2 demand within the OMZ. If equatorial Pacific winds resume their predicted weakening trend, the ocean’s largest anoxic zone will contract despite a global O2 decline. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JASTP..59.1035P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JASTP..59.1035P">RAPIER: a new relocatable VHF coherent radar</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Popple, M.; Chapman, P. J.; Thomas, E. C.; Jones, T. B. 1997-06-01 VHF coherent radar observations of the high latitude ionosphere have contributed significantly to our understanding of the complex processes which couple the ionosphere, magnetosphere and the solar wind. In addition, these observations have also improved our knowledge of the physics of the ionospheric plasma irregularities and their scattering properties. In this article the design of a new mobile coherent radar system is described. The new system, RAPIER (Relocatable Auroral Polar Ionospheric Radar), was initially collocated with the existing SABRE radar and simultaneous operations undertaken to evaluate RAPIER's performance in its beam scanning mode. In this way the performance of the new system was quantitatively compared with that of a well established auroral radar facility. The velocities measured by the new RAPIER system are well correlated with those observed by SABRE. The received backscatter powers observed by the two systems were, however, less well correlated, mainly caused by differences between their respective antenna elevation polar diagrams. As expected from system considerations, SABRE was found to be more sensitive than RAPIER at slant ranges corresponding to the maxima in the SABRE elevation polar diagrams. However, RAPIER's improved elevation polar diagram, superior instantaneous dynamic range and its ability to alter its receiver gain with pointing direction ensured that it could accurately measure targets over a much greater spatial region than SABRE. This effect became more pronounced when regions of intense backscatter were monitored. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005GMS...159...71I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005GMS...159...71I">ULF waves associated with enhanced subauroral proton precipitation</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Immel, Thomas J.; Mende, S. B.; Frey, H. U.; Patel, J.; Bonnell, J. W.; Engebretson, M. J.; Fuselier, S. A. Several types of sub-auroral proton precipitation events have been identified using the Spectrographic Imager (SI) onboard the NASA-IMAGE satellite, including dayside subauroral proton flashes and detached proton arcs in the dusk sector. These have been observed at various levels of geomagnetic activity and solar wind conditions and the mechanism driving the precipitation has often been assumed to be scattering of protons into the loss cone by enhancement of ion-cyclotron waves in the interaction of the thermal plasmaspheric populations and more energetic ring current particles. Indeed, recent investigation of the detached arcs using the MPA instruments aboard the LANL geosynchronous satellites has shown there are nearly always heightened densities of cold plasma on high-altitude field lines which map down directly to the sub-auroral precipitation. If the ion-cyclotron instability is a causative mechanism, the enhancement of wave activity at ion-cyclotron frequencies should be measurable. It is here reported that magnetic pulsations in the Pc1 range occur in the vicinity of each of 4 detached arcs observed in 2000-2002, though with widely varying signatures. Additionally, longer period pulsations in the Pc5 ranges are also observed in the vicinity of the arcs, leading to the conclusion that a bounce-resonance of ring-current protons with the azimuthal Pc5 wave structure may also contribute to the detached precipitation. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BoLMe.tmp....5T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BoLMe.tmp....5T">Influence of the Surf Zone on the Marine Aerosol Concentration in a Coastal Area</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Tedeschi, Gilles; van Eijk, Alexander M. J.; Piazzola, Jacques; Kusmierczyk-Michulec, Jolanta T. 2017-01-01 Sea-salt aerosol concentrations in the coastal zone are assessed with the numerical aerosol-transport model MACMod that applies separate aerosol source functions for open ocean and the surf zone near the sea-land transition. Numerical simulations of the aerosol concentration as a function of offshore distance from the surf zone compare favourably with experimental data obtained during a surf-zone aerosol experiment in Duck, North Carolina in autumn 2007. Based on numerical simulations, the effect of variations in aerosol production (source strength) and transport conditions (wind speed, air-sea temperature difference), we show that the surf-zone aerosols are replaced by aerosols generated over the open ocean as the airmass advects out to sea. The contribution from the surf-generated aerosol is significant during high wind speeds and high wave events, and is significant up to 30 km away from the production zone. At low wind speeds, the oceanic component dominates, except within 1-5 km of the surf zone. Similar results are obtained for onshore flow, where no further sea-salt aerosol production occurs as the airmass advects out over land. The oceanic aerosols that are well-mixed throughout the boundary layer are then more efficiently transported inland than are the surf-generated aerosols, which are confined to the first few tens of metres above the surface, and are therefore also more susceptible to the type of surface (trees or grass) that determines the deposition velocity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AeoRe..16...11W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AeoRe..16...11W">Deceleration efficiencies of shrub windbreaks in a wind tunnel</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Wu, Xiaoxu; Zou, Xueyong; Zhou, Na; Zhang, Chunlai; Shi, Sha 2015-03-01 Artemisia and Salix are dominant shrub species for windbreaks in arid areas of China, and they show similar features to shrubs in other arid areas of the world. We compared the mean velocity fields and shelter effects of two shrub windbreaks with different layouts. For a single plant of Artemisia, the higher the free airflow velocity is, the more the wind velocity around two sides of the plant increases. The velocity gradient around a single plant of Salix is smaller than that around an Artemisia plant due to the difference in the plant shapes. Seven new velocity zones in the horizontal direction appear when airflow passes through an Artemisia windbreak, including four deceleration zones and three acceleration zones. The mean velocity field that is affected by a Salix windbreak can be divided into a deceleration zone in the front, an acceleration zone above, a vortex zone behind and a restoration zone downwind of the vortex zone. Shelter effects of the shrub windbreaks vary with the wind velocity and are influenced by the construct of the windbreaks. Shrub windbreaks that have a complex construction have better shelter effects than simple ones. The shelter effects of plant windbreaks are also influenced by the growth features of the plants. Considering the plant characteristics and the shelter effects of Salix and Artemisia windbreaks, it is optimal to plant these two windbreaks together in a sand-control system. This research is intended to be useful for sand movement control in arid areas. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AtmEn.174..214R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AtmEn.174..214R">Factors associated with NO2 and NOX concentration gradients near a highway</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Richmond-Bryant, J.; Snyder, M. G.; Owen, R. C.; Kimbrough, S. 2018-02-01 The objective of this research is to learn how the near-road gradient, in which NO2 and NOX (NO + NO2) concentrations are elevated, varies with changes in meteorological and traffic variables. Measurements of NO2 and NOX were obtained east of I-15 in Las Vegas and fit to functions whose slopes (dCNO2/dx and dCNOX/dx, respectively) characterize the size of the near-road zone where NO2 and NOX concentrations from mobile sources on the highway are elevated. These metrics were used to learn about the near-road gradient by modeling dCNO2/dx and dCNOX/dx as functions of meteorological variables (e.g., wind direction, wind speed), traffic (vehicle count), NOX concentration upwind of the road, and O3 concentration at two fixed-site ambient monitors. Generalized additive models (GAM) were used to model dCNO2/dx and dCNOX/dx versus the independent variables because they allowed for nonlinearity of the variables being compared. When data from all wind directions were included in the analysis, variability in O3 concentration comprised the largest proportion of variability in dCNO2/dx, followed by variability in wind direction. In a second analysis constrained to winds from the west, variability in O3 concentration remained the largest contributor to variability in dCNO2/dx, but the relative contribution of variability in wind speed to variability in dCNO2/dx increased relative to its contribution for the all-wind analysis. When data from all wind directions were analyzed, variability in wind direction was by far the largest contributor to variability in dCNOX/dx, with smaller contributions from hour of day and upwind NOX concentration. When only winds from the west were analyzed, variability in upwind NOX concentration, wind speed, hour of day, and traffic count all were associated with variability in dCNOX/dx. Increases in O3 concentration were associated with increased magnitude near-road dCNO2/dx, possibly shrinking the zone of elevated concentrations occurring near roads. Wind direction parallel to the highway was also related to an increased magnitude of both dCNO2/dx and dCNOX/dx, again likely shrinking the zone of elevated concentrations occurring near roads. Wind direction perpendicular to the road decreased the magnitude of dCNO2/dx and dCNOX/dx and likely contributed to growth of the zone of elevated concentrations occurring near roads. Thus, variability in near-road concentrations is influenced by local meteorology and ambient O3 concentration. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM22A..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM22A..03S">Polar CAP Boundary Identification Using Redline Imaging Data</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Spanswick, E.; Roy, E. A.; Gallardo-Lacourt, B.; Donovan, E.; Ridley, A. J.; Gou, D. 2017-12-01 The location of the polar cap boundary is typically detected using low-orbit satellite measurements in which the boundary is identified by its unique signature of a sharp decrease in energy and particle flux poleward of the auroral oval. A previous study based in optical data by Blanchard et al. [1995] suggested that a dramatic gradient in redline aurora may also be an indicator of the polar cap boundary. While this study has been heavily cited, it was only based on few events and its findings have largely gone uncontested. Since the Blanchard study, satellite instrumentation and available auroral data have improved significantly. Auroral imaging has moved well beyond the capabilities of the instrumentation in the previous study in terms of sensitivity and both spatial and temporal resolution. We now have access to decades of optical data from arrays spanning a huge spatial range; none of which was available previously. In this study we have used data from FAST and DMSP satellites in conjunction with the University of Calgary's Narrow-band All-sky Cameras for Auroral Monitoring (NASCAM) ground based auroral imaging array and the REdline Geospace Observatory (REGO) data to assess the viability of automated detection of the polar cap boundary. In our analysis we used redline (630nm) auroral signatures from the ground based imagers around the location of the polar cap boundary observed in satellite data. We have characterized the polar cap boundary luminosity and location using the redline auroral data during different geomagnetic conditions. Our results enable a new tool to automatically identify the polar cap boundary to reach a deeper understanding of the connection between polar cap location and auroral activity. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSM41A2666H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSM41A2666H">Validation of Ground-based Optical Estimates of Auroral Electron Precipitation Energy Deposition</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Hampton, D. L.; Grubbs, G. A., II; Conde, M.; Lynch, K. A.; Michell, R.; Zettergren, M. D.; Samara, M.; Ahrns, M. J. 2017-12-01 One of the major energy inputs into the high latitude ionosphere and mesosphere is auroral electron precipitation. Not only does the kinetic energy get deposited, the ensuing ionization in the E and F-region ionosphere modulates parallel and horizontal currents that can dissipate in the form of Joule heating. Global models to simulate these interactions typically use electron precipitation models that produce a poor representation of the spatial and temporal complexity of auroral activity as observed from the ground. This is largely due to these precipitation models being based on averages of multiple satellite overpasses separated by periods much longer than typical auroral feature durations. With the development of regional and continental observing networks (e.g. THEMIS ASI), the possibility of ground-based optical observations producing quantitative estimates of energy deposition with temporal and spatial scales comparable to those known to be exhibited in auroral activity become a real possibility. Like empirical precipitation models based on satellite overpasses such optics-based estimates are subject to assumptions and uncertainties, and therefore require validation. Three recent sounding rocket missions offer such an opportunity. The MICA (2012), GREECE (2014) and Isinglass (2017) missions involved detailed ground based observations of auroral arcs simultaneously with extensive on-board instrumentation. These have afforded an opportunity to examine the results of three optical methods of determining auroral electron energy flux, namely 1) ratio of auroral emissions, 2) green line temperature vs. emission altitude, and 3) parametric estimates using white-light images. We present comparisons from all three methods for all three missions and summarize the temporal and spatial scales and coverage over which each is valid. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830013407','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830013407">Mirror instability and origin of morningside auroral structure</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chiu, Y. T.; Schulz, M.; Fennell, J. F.; Kishi, A. M. 1983-01-01 Auroral optical imagery shows marked differences between auroral features of the evening and morning sectors: the separation between diffuse and discrete auroras in the evening sector is not distinct in the morning sector, which is dominated by auroral patches and multiple banded structures aligned along some direction. Plasma distribution function signatures also show marked differences: downward electron beams and inverted-V signatures prefer the evening sector, while the electron spectra on the morning sector are similar to the diffuse aurora. A theory of morningside auroras consistent with these features was constructed. The theory is based on modulation of the growth rates of electron cyclotron waves by the mirror instability, which is in turn driven by inward-convected ions that have become anisotropic. This modulation produces alternating bands of enhanced and reduced electron precipitation which approximate the observed multiple auroral bands and patches of the morning sector. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20180000745&hterms=application+spaces&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dapplication%2Bspaces','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20180000745&hterms=application+spaces&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dapplication%2Bspaces">First Application of the Zeeman Technique to Remotely Measure Auroral Electrojet Intensity From Space</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Yee, J. H.; Gjerloev, J.; Wu, D.; Schwartz, M. J. 2017-01-01 Using the O2 118 GHz spectral radiance measurements obtained by the Microwave Limb Sounder instrument on board the Aura spacecraft, we demonstrate that the Zeeman effect can be used to remotely measure the magnetic field perturbations produced by the auroral electrojet near the Hall current closure altitudes. Our derived current-induced magnetic field perturbations are found to be highly correlated with those coincidently obtained by ground magnetometers. These perturbations are also found to be linearly correlated with auroral electrojet strength. The statistically derived polar maps of our measured magnetic field perturbation reveal a spatial-temporal morphology consistent with that produced by the Hall current during substorms and storms. With today's technology, a constellation of compact, low-power, high spectral-resolution cubesats would have the capability to provide high precision and spatiotemporal magnetic field samplings needed for auroral electrojet measurements to gain insights into the spatiotemporal behavior of the auroral electrojet system. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active">24</li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active">25</li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMSM11A1590T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMSM11A1590T">The sub-auroral electric field as observed by DMSP and the new SuperDARN mid-latitude radars</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Talaat, E. R.; Sotirelis, T.; Hairston, M. R.; Ruohoniemi, J. M.; Greenwald, R. A.; Lester, M. 2008-12-01 In this paper we present analyses of the sub-auroral electric field environment as observed from both space and ground. We discuss the dependency of the configuration and strength of the sub-auroral electric field on IMF and geomagnetic activity, longitudinal, seasonal, and solar cycle variability. Primarily, e use ~20 years of electric field measurement dataset derived from the suite of DMSP ion drift meters. A major component of our analysis is correctly specifying the aurora boundary, as the behavior and magnitude of these fields will be drastically different away from the high-conductance auroral oval. As such, we use the coincident particle flux measurements from the DMSP SSJ4 monitors. We also present the solar minimum observations of the sub-auroral flow newly available from the mid-latitude SuperDARN radars at Wallops and Blackstone in Virginia. Preliminary comparisons between these flows and the DMSP climatology are discussed. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19720029850&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dnike','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19720029850&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dnike">Field-aligned particle currents near an auroral arc.</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Choy, L. W.; Arnoldy, R. L.; Potter, W.; Kintner, P.; Cahill, L. J., Jr. 1971-01-01 A Nike-Tomahawk rocket equipped to measure electric and magnetic fields and charged particles from a few eV to several hundred keV energy was flown into an auroral band on April 11, 1970. The purpose of this flight was to obtain evidence of the low-energy electrons and protons that constitute a field-aligned sheet current, and also to obtain the magnetic signature of such a current and the electric field in and near the auroral-arc electric current system. Particular attention was given to a sudden increase in the field-aligned current associated with a prior sudden increase in the electric field and a sudden change in the magnetic field, all occurring near the edge of a visual auroral arc. Data obtained are discussed and analyzed; they present an important contribution to the problem of mapping of atmospheric auroral phenomena to the magnetospheric equatorial plane. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title24-vol5/pdf/CFR-2011-title24-vol5-sec3280-404.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title24-vol5/pdf/CFR-2011-title24-vol5-sec3280-404.pdf">24 CFR 3280.404 - Standard for egress windows and devices for use in manufactured homes.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a> 2011-04-01 ... interior pressure tests for components and cladding must be conducted at the design wind loads required by... in high wind areas. For homes designed to be located in Wind Zones II and III, manufacturers shall... egress window openings. This method must be capable of resisting the design wind pressures specified in... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3280-404.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title24-vol5/pdf/CFR-2012-title24-vol5-sec3280-404.pdf">24 CFR 3280.404 - Standard for egress windows and devices for use in manufactured homes.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a> 2012-04-01 ... interior pressure tests for components and cladding must be conducted at the design wind loads required by... in high wind areas. For homes designed to be located in Wind Zones II and III, manufacturers shall... egress window openings. This method must be capable of resisting the design wind pressures specified in... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3280-404.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title24-vol5/pdf/CFR-2013-title24-vol5-sec3280-404.pdf">24 CFR 3280.404 - Standard for egress windows and devices for use in manufactured homes.</a> <a target="_blank" rel="noopener noreferrer" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a> 2013-04-01 ... interior pressure tests for components and cladding must be conducted at the design wind loads required by... in high wind areas. For homes designed to be located in Wind Zones II and III, manufacturers shall... egress window openings. This method must be capable of resisting the design wind pressures specified in... </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020074705','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020074705">Lunar Radar Cross Section at Low Frequency</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Rodriguez, P.; Kennedy, E. J.; Kossey, P.; McCarrick, M.; Kaiser, M. L.; Bougeret, J.-L.; Tokarev, Y. V. 2002-01-01 Recent bistatic measurements of the lunar radar cross-section have extended the spectrum to long radio wavelength. We have utilized the HF Active Auroral Research Program (HAARP) radar facility near Gakona, Alaska to transmit high power pulses at 8.075 MHz to the Moon; the echo pulses were received onboard the NASA/WIND spacecraft by the WAVES HF receiver. This lunar radar experiment follows our previous use of earth-based HF radar with satellites to conduct space experiments. The spacecraft was approaching the Moon for a scheduled orbit perturbation when our experiment of 13 September 2001 was conducted. During the two-hour experiment, the radial distance of the satellite from the Moon varied from 28 to 24 Rm, where Rm is in lunar radii. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016STP.....2c..43L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016STP.....2c..43L">Geomagnetic effects caused by rocket exhaust jets</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Lipko, Yuriy; Pashinin, Aleksandr; Khakhinov, Vitaliy; Rahmatulin, Ravil 2016-09-01 In the space experiment Radar-Progress, we have made 33 series of measurements of geomagnetic variations during ignitions of engines of Progress cargo spacecraft in low Earth orbit. We used magneto-measuring complexes, installed at observatories of the Institute of Solar-Terrestrial Physics of Siberian Branch of the Russian Academy of Sciences, and magnetotelluric equipment of a mobile complex. We assumed that engine running can cause geomagnetic disturbances in flux tubes crossed by the spacecraft. When analyzing experimental data, we took into account space weather factors: solar wind parameters, total daily mid-latitude geomagnetic activity index Kp, geomagnetic auroral electrojet index AE, global geomagnetic activity. The empirical data we obtained indicate that 18 of the 33 series showed geomagnetic variations in various time ranges. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AdSpR..61.1636M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AdSpR..61.1636M">All-sky-imaging capabilities for ionospheric space weather research using geomagnetic conjugate point observing sites</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Martinis, C.; Baumgardner, J.; Wroten, J.; Mendillo, M. 2018-04-01 Optical signatures of ionospheric disturbances exist at all latitudes on Earth-the most well known case being visible aurora at high latitudes. Sub-visual emissions occur equatorward of the auroral zones that also indicate periods and locations of severe Space Weather effects. These fall into three magnetic latitude domains in each hemisphere: (1) sub-auroral latitudes ∼40-60°, (2) mid-latitudes (20-40°) and (3) equatorial-to-low latitudes (0-20°). Boston University has established a network of all-sky-imagers (ASIs) with sites at opposite ends of the same geomagnetic field lines in each hemisphere-called geomagnetic conjugate points. Our ASIs are autonomous instruments that operate in mini-observatories situated at four conjugate pairs in North and South America, plus one pair linking Europe and South Africa. In this paper, we describe instrument design, data-taking protocols, data transfer and archiving issues, image processing, science objectives and early results for each latitude domain. This unique capability addresses how a single source of disturbance is transformed into similar or different effects based on the unique "receptor" conditions (seasonal effects) found in each hemisphere. Applying optical conjugate point observations to Space Weather problems offers a new diagnostic approach for understanding the global system response functions operating in the Earth's upper atmosphere. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18680411','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18680411">JIRAM, the image spectrometer in the near infrared on board the Juno mission to Jupiter.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Adriani, Alberto; Coradini, Angioletta; Filacchione, Gianrico; Lunine, Jonathan I; Bini, Alessandro; Pasqui, Claudio; Calamai, Luciano; Colosimo, Fedele; Dinelli, Bianca M; Grassi, Davide; Magni, Gianfranco; Moriconi, Maria L; Orosei, Roberto 2008-06-01 The Jovian InfraRed Auroral Mapper (JIRAM) has been accepted by NASA for inclusion in the New Frontiers mission "Juno," which will launch in August 2011. JIRAM will explore the dynamics and the chemistry of Jupiter's auroral regions by high-contrast imaging and spectroscopy. It will also analyze jovian hot spots to determine their vertical structure and infer possible mechanisms for their formation. JIRAM will sound the jovian meteorological layer to map moist convection and determine water abundance and other constituents at depths that correspond to several bars pressure. JIRAM is equipped with a single telescope that accommodates both an infrared camera and a spectrometer to facilitate a large observational flexibility in obtaining simultaneous images in the L and M bands with the spectral radiance over the central zone of the images. Moreover, JIRAM will be able to perform spectral imaging of the planet in the 2.0-5.0 microm interval of wavelengths with a spectral resolution better than 10 nm. Instrument design, modes, and observation strategy will be optimized for operations onboard a spinning satellite in polar orbit around Jupiter. The JIRAM heritage comes from Italian-made, visual-infrared imaging spectrometers dedicated to planetary exploration, such as VIMS-V on Cassini, VIRTIS on Rosetta and Venus Express, and VIR-MS on the Dawn mission. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......208C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......208C">Configuration and Generation of Substorm Current Wedge</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Chu, Xiangning The substorm current wedge (SCW), a core element of substorm dynamics coupling the magnetotail to the ionosphere, is crucial in understanding substorms. It has been suggested that the field-aligned currents (FACs) in the SCW are caused by either pressure gradients or flow vortices, or both. Our understanding of FAC generations is based predominately on numerical simulations, because it has not been possible to organize spacecraft observations in a coordinate system determined by the SCW. This dissertation develops an empirical inversion model of the current wedge and inverts midlatitude magnetometer data to obtain the parameters of the current wedge for three solar cycles. This database enables statistical data analysis of spacecraft plasma and magnetic field observations relative to the SCW coordinate. In chapter 2, a new midlatitude positive bay (MPB) index is developed and calculated for three solar cycles of data. The MPB index is processed to determine the substorm onset time, which is shown to correspond to the auroral breakup onset with at most 1-2 minutes difference. Substorm occurrence rate is found to depend on solar wind speed while substorm duration is rather constant, suggesting that substorm process has an intrinsic pattern independent of external driving. In chapter 3, an SCW inversion technique is developed to determine the strength and locations of the FACs in an SCW. The inversion parameters for FAC strength and location, and ring current strength are validated by comparison with other measurements. In chapter 4, the connection between earthward flows and auroral poleward expansion is examined using improved mapping, obtained from a newly-developed dynamic magnetospheric model by superimposing a standard magnetospheric field model with substorm current wedge obtained from the inversion technique. It is shown that the ionospheric projection of flows observed at a fixed point in the equatorial plane map to the bright aurora as it expands poleward, suggesting that auroral poleward expansion is mainly a consequence of magnetic dipolarization caused by the SCW. Chapter 5 shows that increased plasma pressure caused by flow braking has a temporal pattern similar to that of the currents in the SCW. In contrast, flow vortices vanish quickly, suggesting that pressure gradient is an important factor in generating the SCW. The measured pressure gradients are found to be organized relative to SCW central meridian. Nonalignment between pressure gradient and flux tube volume gradient lead to the generation of an SCW with quadrupole FACs (inner and outer loop of FACs). Because the inner current loop is weaker than the outer loop, the combined magnetic effect of the two current loops is similar to a classic SCW. The final chapter studies the magnetic flux transport by earthward flows, and accumulated inside the SCW and enclosed within auroral poleward boundary. Their good agreement suggests that flux accumulation causes magnetic dipolarization and auroral poleward expansion. The strength of the SCW is positively correlated with the amount of magnetic flux accumulated. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007783','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007783">Global Response to Local Ionospheric Mass Ejection</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Moore, T. E.; Fok, M.-C.; Delcourt, D. C.; Slinker, S. P.; Fedder, J. A. 2010-01-01 We revisit a reported "Ionospheric Mass Ejection" using prior event observations to guide a global simulation of local ionospheric outflows, global magnetospheric circulation, and plasma sheet pressurization, and comparing our results with the observed global response. Our simulation framework is based on test particle motions in the Lyon-Fedder-Mobarry (LFM) global circulation model electromagnetic fields. The inner magnetosphere is simulated with the Comprehensive Ring Current Model (CRCM) of Fok and Wolf, driven by the transpolar potential developed by the LFM magnetosphere, and includes an embedded plasmaspheric simulation. Global circulation is stimulated using the observed solar wind conditions for the period 24-25 Sept 1998. This period begins with the arrival of a Coronal Mass Ejection, initially with northward, but later with southward interplanetary magnetic field. Test particles are launched from the ionosphere with fluxes specified by local empirical relationships of outflow to electrodynamic and particle precipitation imposed by the MIlD simulation. Particles are tracked until they are lost from the system downstream or into the atmosphere, using the full equations of motion. Results are compared with the observed ring current and a simulation of polar and auroral wind outflows driven globally by solar wind dynamic pressure. We find good quantitative agreement with the observed ring current, and reasonable qualitative agreement with earlier simulation results, suggesting that the solar wind driven global simulation generates realistic energy dissipation in the ionosphere and that the Strangeway relations provide a realistic local outflow description. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcDyn..67.1251X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcDyn..67.1251X">Numerical modelling of wind effects on breaking waves in the surf zone</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Xie, Zhihua 2017-10-01 Wind effects on periodic breaking waves in the surf zone have been investigated in this study using a two-phase flow model. The model solves the Reynolds-averaged Navier-Stokes equations with the k - 𝜖 turbulence model simultaneously for the flows both in the air and water. Both spilling and plunging breakers over a 1:35 sloping beach have been studied under the influence of wind, with a focus during wave breaking. Detailed information of the distribution of wave amplitudes and mean water level, wave-height-to-water-depth ratio, the water surface profiles, velocity, vorticity, and turbulence fields have been presented and discussed. The inclusion of wind alters the air flow structure above water waves, increases the generation of vorticity, and affects the wave shoaling, breaking, overturning, and splash-up processes. Wind increases the water particle velocities and causes water waves to break earlier and seaward, which agrees with the previous experiment. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20160013719&hterms=Hofmann&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DHofmann','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20160013719&hterms=Hofmann&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DHofmann">VLTI-AMBER Velocity-Resolved Aperture-Synthesis Imaging of Eta Carinae with a Spectral Resolution of 12 000: Studies of the Primary Star Wind and Innermost Wind-Wind Collision Zone</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Weigelt, G.; Hofmann, K.-H.; Schertl, D.; Clementel, N.; Corcoran, M. F.; Damineli, A.; de Wit, W.-J.; Grellmann, R.; Groh, J.; Guieu, S.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20160013719'); toggleEditAbsImage('author_20160013719_show'); toggleEditAbsImage('author_20160013719_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20160013719_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20160013719_hide"> 2016-01-01 The mass loss from massive stars is not understood well. Eta Carinae is a unique object for studying the massive stellar wind during the luminous blue variable phase. It is also an eccentric binary with a period of 5.54 yr. The nature of both stars is uncertain, although we know from X-ray studies that there is a wind-wind collision whose properties change with orbital phase. Aims. We want to investigate the structure and kinematics of Car's primary star wind and wind-wind collision zone with a high spatial resolution of approx.6 mas (approx.14 au) and high spectral resolution of R = 12 000. Methods. Observations of Car were carried out with the ESO Very Large Telescope Interferometer (VLTI) and the AMBER instrument between approximately five and seven months before the August 2014 periastron passage. Velocity-resolved aperture-synthesis images were reconstructed from the spectrally dispersed interferograms. Interferometric studies can provide information on the binary orbit, the primary wind, and the wind collision. Results. We present velocity-resolved aperture-synthesis images reconstructed in more than 100 di erent spectral channels distributed across the Br(gamma) 2.166 micron emission line. The intensity distribution of the images strongly depends on wavelength. At wavelengths corresponding to radial velocities of approximately -140 to -376 km/s measured relative to line center, the intensity distribution has a fan-shaped structure. At the velocity of -277 km/s, the position angle of the symmetry axis of the fan is 126. The fan-shaped structure extends approximately 8.0 mas (approx.18:8 au) to the southeast and 5.8 mas (approx.13:6 au) to the northwest, measured along the symmetry axis at the 16% intensity contour. The shape of the intensity distributions suggests that the obtained images are the first direct images of the innermost wind-wind collision zone. Therefore, the observations provide velocity-dependent image structures that can be used to test three-dimensional hydrodynamical, radiative transfer models of the massive interacting winds of Eta Car. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........73S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........73S">Kilometer-Spaced GNSS Array for Ionospheric Irregularity Monitoring</a> <a target="_blank" rel="noopener noreferrer" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a> Su, Yang This dissertation presents automated, systematic data collection, processing, and analysis methods for studying the spatial-temporal properties of Global Navigation Satellite Systems (GNSS) scintillations produced by ionospheric irregularities at high latitudes using a closely spaced multi-receiver array deployed in the northern auroral zone. The main contributions include 1) automated scintillation monitoring, 2) estimation of drift and anisotropy of the irregularities, 3) error analysis of the drift estimates, and 4) multi-instrument study of the ionosphere. A radio wave propagating through the ionosphere, consisting of ionized plasma, may suffer from rapid signal amplitude and/or phase fluctuations known as scintillation. Caused by non-uniform structures in the ionosphere, intense scintillation can lead to GNSS navigation and high-frequency (HF) communication failures. With specialized GNSS receivers, scintillation can be studied to better understand the structure and dynamics of the ionospheric irregularities, which can be parameterized by altitude, drift motion, anisotropy of the shape, horizontal spatial extent and their time evolution. To study the structuring and motion of ionospheric irregularities at the sub-kilometer scale sizes that produce L-band scintillations, a closely-spaced GNSS array has been established in the auroral zone at Poker Flat Research Range, Alaska to investigate high latitude scintillation and irregularities. Routinely collecting low-rate scintillation statistics, the array database also provides 100 Hz power and phase data for each channel at L1/L2C frequency. In this work, a survey of seasonal and hourly dependence of L1 scintillation events over the course of a year is discussed. To efficiently and systematically study scintillation events, an automated low-rate scintillation detection routine is established and performed for each day by screening the phase scintillation index. The spaced-receiver technique is applied to cross-correlated phase and power measurements from GNSS receivers. Results of horizontal drift velocities and anisotropy ellipses derived from the parameters are shown for several detected events. Results show the possibility of routinely quantifying ionospheric irregularities by drifts and anisotropy. Error analysis on estimated properties is performed to further evaluate the estimation quality. Uncertainties are quantified by ensemble simulation of noise on the phase signals carried through to the observations of the spaced-receiver linear system. These covariances are then propagated through to uncertainties on drifts. A case study of a single scintillating satellite observed by the array is used to demonstrate the uncertainty estimation process. The distributed array is used in coordination with other measuring techniques such as incoherent scatter radar and optical all-sky imagers. These scintillations are correlated with auroral activity, based on all-sky camera images. Measurements and uncertainty estimates made over a 30-minute period are made and compared to a collocated incoherent scatter radar, and show good agreement in horizontal drift speed and direction during periods of scintillation for cases when the characteristic velocity is less than the drift velocity. The methods demonstrated are extensible to other zones and other GNSS arrays of varying size, number, ground distribution, and transmitter frequency. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160007821','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160007821">Spacecraft Charging and Auroral Boundary Predictions in Low Earth Orbit</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Minow, Joseph I. 2016-01-01 Auroral charging of spacecraft is an important class of space weather impacts on technological systems in low Earth orbit. In order for space weather models to accurately specify auroral charging environments, they must provide the appropriate plasma environment characteristics responsible for charging. Improvements in operational space weather prediction capabilities relevant to charging must be tested against charging observations. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740048173&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dnike','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740048173&hterms=nike&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dnike">Field aligned currents and the auroral spectrum below 1 keV</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Arnoldy, R. L. 1973-01-01 Measurements during auroral events were conducted with the aid of detectors flown aboard three Nike-Tomahawk rocket flights. The detectors used to measure the auroral spectrum below 1 keV consisted of electrostatic analyzers positioned in the rocket to measure particles moving up and down the magnetic field lines. The analyzers measured electrons and protons simultaneously during a given sweep. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830053141&hterms=rio+grande+sul&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drio%2Bgrande%2Bsul','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830053141&hterms=rio+grande+sul&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Drio%2Bgrande%2Bsul">Excitation of whistler waves by reflected auroral electrons</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Wu, C. S.; Dillenburg, D.; Ziebell, L. F.; Freund, H. P. 1983-01-01 Excitation of electron waves and whistlers by reflected auroral electrons which possess a loss-cone distribution is investigated. Based on a given magnetic field and density model, the instability problem is studied over a broad region along the auroral field lines. This region covers altitudes ranging from one quarter of an earth radius to five earth radii. It is found that the growth rate is significant only in the region of low altitude, say below the source region of the auroral kilometric radiation. In the high altitude region the instability is insignificant either because of low refractive indices or because of small loss cone angles. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17817466','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17817466">Auroral-particle precipitation and trapping caused by electrostatic double layers in the ionosphere.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Albert, R D; Lindstrom, P J 1970-12-25 Interpretation of high-resolution angular distribution measurements of the primary auroral electron flux detected by a rocket probe launched into a visible aurora from Fort Churchill in the fall of 1966 leads to the following conclusions. The auroral electron flux is nearly monoenergetic and has a quasi-trapped as well as a precipitating component. The quasi-trapped flux appears to be limited to a region defined by magnetic-mirror points and multiple electrostatic double layers in the ionosphere. The electrostatic field of the double-layer distribution enhances the aurora by lowering the magnetic-mirror points and supplying energy to the primary auroral electrons. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140006451','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140006451">DMSP Auroral Charging at Solar Cycle 24 Maximum</a> <a target="_blank" rel="noopener noreferrer" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a> Chandler, M.; Parker, L. Neergaard; Minow, J. I. 2013-01-01 It has been well established that polar orbiting satellites can experience mild to severe auroral charging levels (on the order of a few hundred volts to few kilovolts negative frame potentials) during solar minimum conditions. These same studies have shown a strong reduction in charging during the rising and declining phases of the past few solar cycles with a nearly complete suppression of auroral charging at solar maximum. Recently, we have observed examples of high level charging during the recent approach to Solar Cycle 24 solar maximum conditions not unlike those reported by Frooninckx and Sojka. These observations demonstrate that spacecraft operations during solar maximum cannot be considered safe from auroral charging when solar activity is low. We present a survey of auroral charging events experienced by the Defense Meteorological Satellite Program (DMSP) F16 satellite during Solar Cycle 24 maximum conditions. We summarize the auroral energetic particle environment and the conditions necessary for charging to occur in this environment, we describe how the lower than normal solar activity levels for Solar Cycle 24 maximum conditions are conducive to charging in polar orbits, and we show examples of the more extreme charging events, sometimes exceeding 1 kV, during this time period. </li> <li> <a target="_blank" rel="noopener noreferrer" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17812894','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17812894">Magnetic fields at uranus.</a> <a target="_blank" rel="noopener noreferrer" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a> Ness, N F; Acuña, M H; Behannon, K W; Burlaga, L F; Connerney, J E; Lepping, R P; Neubauer, F M 1986-07-04 The magnetic field experiment on the Voyager 2 spacecraft revealed a strong planetary magnetic field of Uranus and an associated magnetosphere and fully developed bipolar masnetic tail. The detached bow shock wave in the solar wind supersonic flow was observed upstream at 23.7 Uranus radii (1 R(U) = 25,600 km) and the magnetopause boundary at 18.0 R(U), near the planet-sun line. A miaximum magnetic field of 413 nanotesla was observed at 4.19 R(U ), just before closest approach. Initial analyses reveal that the planetary magnetic field is well represented by that of a dipole offset from the center of the planet by 0.3 R(U). The angle between Uranus' angular momentum vector and the dipole moment vector has the surprisingly large value of 60 degrees. Thus, in an astrophysical context, the field of Uranus may be described as that of an oblique rotator. The dipole moment of 0.23 gauss R(3)(U), combined with the large spatial offset, leads to minimum and maximum magnetic fields on the surface of the planet of approximately 0.1 and 1.1 gauss, respectively. The rotation period of the magnetic field and hence that of the interior of the planet is estimated to be 17.29+/- 0.10 hours; the magnetotail rotates about the planet-sun line with the same period. Thelarge offset and tilt lead to auroral zones far from the planetary rotation axis poles. The rings and the moons are embedded deep within the magnetosphere, and, because of the large dipole tilt, they will have a profound and diurnally varying influence as absorbers of the trapped radiation belt particles. </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active">25</li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> </div> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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Sample records for wind auroral zone