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Sample records for ionospheric plasma convection

  1. Strong IMF By-Related Plasma Convection in the Ionosphere and Cusp Field-Aligned Currents Under Northward IMF Conditions

    NASA Technical Reports Server (NTRS)

    Le, G.; Lu, G.; Strangeway, R. J.; Pfaff, R. F., Jr.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    We present in this paper an investigation of IMF-By related plasma convection and cusp field-aligned currents using FAST data and AMIE model during a prolonged interval with large positive IMF By and northward Bz conditions (By/Bz much greater than 1). Using the FAST single trajectory observations to validate the global convection patterns at key times and key locations, we have demonstrated that the AMIE procedure provides a reasonably good description of plasma circulations in the ionosphere during this interval. Our results show that the plasma convection in the ionosphere is consistent with the anti-parallel merging model. When the IMF has a strongly positive By component under northward conditions, we find that the global plasma convection forms two cells oriented nearly along the Sun-earth line in the ionosphere. In the northern hemisphere, the dayside cell has clockwise convection mainly circulating within the polar cap on open field lines. A second cell with counterclockwise convection is located in the nightside circulating across the polar cap boundary, The observed two-cell convection pattern appears to be driven by the reconnection along the anti-parallel merging lines poleward of the cusp extending toward the dusk side when IMF By/Bz much greater than 1. The magnetic tension force on the newly reconnected field lines drives the plasma to move from dusk to dawn in the polar cusp region near the polar cap boundary. The field-aligned currents in the cusp region flow downward into the ionosphere. The return field-aligned currents extend into the polar cap in the center of the dayside convection cell. The field-aligned currents are closed through the Peterson currents in the ionosphere, which flow poleward from the polar cap boundary along the electric field direction.

  2. Is the ionospheric plasma convection causing GOCE's anomalies at the geomagnetic poles?

    NASA Astrophysics Data System (ADS)

    Marz, Stefan; Schlicht, Anja

    2016-04-01

    In the gradients Vyy of the GOCE gravity field mission signals were observed in the region of the poles, which do not exhibit gravity field signatures and therefore suggest distinct systematic errors. In this connection also correlations with the cross track common mode are visible, whereby an insufficient calibration of the gradiometer is generally assumed. In the present thesis a correlation between the cross track common mode and Vyy is highlighted in more detail and the effect by natural low frequency signals in the ionosphere is discussed as another possible reason for the accelerometer deflections. Relating to the cross track accelerations thermospheric winds are the only discussed reason. As a result, it is clear that the distinct signal peaks particularly reveal correlations with the geomagnetic activity, as well as seasonal dependencies. In addition, it can be determined that these signal peaks occur exclusively in the area of polar latitudes and show connections with the areas of polar caps and aurora ovals. The behaviour of the signal peaks further exhibits a distinct influence by the By component of the interplanetary magnetic field. Distinct correlations of the cross track common mode reveal with the ionospheric plasma convection. Regarding the yy gradients it is determined that aspects correlate with the common mode, but the common mode can not explain the full signal.

  3. Plasma and convection reversal boundary motions in the high-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Chen, Y.-J.; Heelis, R. A.; Cumnock, J. A.

    2016-06-01

    In this paper we present a statistical study of the high-latitude ionospheric plasma motion at the convection reversal boundary (CRB) and its dependence on the location of the CRB and the interplanetary magnetic field (IMF) orientation by using the Defense Meteorological Satellite Program (DMSP) F13 and F15 measurements over the period from 2000 to 2007. During periods of stable southward IMF, we find a smaller variability in plasma drifts across the CRB over a 4 h segment in magnetic local time (MLT) around dawn and dusk compared to that for variable IMF. Across these segments, the plasma motion at the CRB is directed poleward at local times closer to local noon and equatorward at local times closer to midnight on both the dawn and dusk sides with a total potential drop ~10 kV, suggesting that the CRB behaves much like an adiaroic line. For variable IMF with no stability constraint, we see a relatively narrow distribution of plasma drifts across the CRB only in the 6-7 h and 17-18 h MLT and equatorward/poleward motions of the CRB when the CRB is located at the highest/lowest latitudes. The smaller local time extent of the adiaroic line for variable IMF (~1 h) may be associated with rotation of the dayside merging gap in local time or local contractions and expansions of the polar cap boundary.

  4. Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitation, Plasma Waves, and Convection Observed by Polar

    NASA Technical Reports Server (NTRS)

    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.; Pollock, C. J.; Gurnett, D. A.; Pickett, J. S.; Persoon, A. M.; Scudder, J. D.; Maynard, N. C.; Mozer, F. S.; Brittnacher, M. J.; Nagai, T.

    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.

  5. Observation of interplanetary magnetic field and of ionospheric plasma convection in the vicinity of the dayside polar cleft

    NASA Technical Reports Server (NTRS)

    Clauer, C. R.; Banks, P. M.; Smith, A. Q.; Jorgensen, T. S.; Friis-Christensen, E.; Vennerstrom, S.; Wickwar, V. B.; Kelly, J. D.; Doupnik, J.

    1984-01-01

    Dayside ionosphere convection at high latitudes has been examined during a series of experiments using the Sondrestrom radar together with ancillary observations of the interplanetary magnetic field (IMF) by the IMP-8 spacecraft. The radar experiments obtained a latitude coverage of 67.6 to 81.3 deg Lambda and a temporal resolution of between 14 to 25 minutes. A total of 17 rotations through the dayside cleft region during April, June and July, 1983 have been examined. The observations show two convection cells with sunward flow at lower latitudes and antisunward flow at higher latitudes. The flow commonly rotates through a 180 deg angle resulting in the predominant appearance of east-west flows. Rapid temporal variations in the convection velocities are frequently observed. Many of the high latitude variations in convection velocity appear to be directly related to variations in the IMF By component, with eastward (westward) velocity associated with negative (positive) By. This is strong evidence for a direct electrical coupling between the solar wind and dayside high latitude ionosphere.

  6. Ionospheric convection associated with discrete levels of particle precipitation

    SciTech Connect

    Foster, J.C.; Holt, J.M.; Musgrove, R.G.; Evans, D.S.

    1986-07-01

    A precipitation index is described which quantifies the intensity and spatial extent of high-latitude particle precipitation based on observations made along individual satellite passes. By sorting plasma-convection data according to this index, average patterns of the ionospheric convection electric field were derived from a data set consisting of five years' observations by the Millstone Hill radar. Reference to the instantaneous precipitation index, and the average patterns keyed to it, provides a means of characterizing the global precipitation and convection patterns throughout an event.

  7. Polar Cap Plasma and Convection

    NASA Technical Reports Server (NTRS)

    Elliott, Heather A.; Craven, Paul D.; Comfort, Richard H.; Chandler, Michael O.; Moore, Thomas E.; Ruohoniemi, J. M.

    1998-01-01

    This presentation will describe the character of the polar cap plasma in 10% AGU Spring 1998 particular the convection velocities at the perigee (about 1.8 Re) and apogee( about 8.9 Re) of Polar in relationship to Interplanetary Magnetic Field (IMF) and solar wind parameters. This plasma is thought to be due to several sources; the polar wind, cleft ion fountain, and auroral outflow. The plasma in the polar cap tends to be mostly field-aligned. At any given point in the polar cap, this plasma could be from a different regions since convection of magnetic field lines can transport this material. it is quite difficult to study such a phenomena with single point measurements. Current knowledge of the polar cap plasma obtained by in situ measurements will be presented along with recent results from the Polar mission. This study also examines the direct electrical coupling between the magnetosphere and ionosphere by comparing convection velocities measured by the Thermal Ion Dynamics Experiment (TIDE) and Magnetic Field Experiment (MFE) instruments in magnetosphere and measurements of the ionosphere by ground-based radars. At times such a comparison is difficult because the Polar satellite at apogee spends a large amount of time in the polar cap which is a region that is not coverage well by the current SuperDam coherent radars. This is impart due to the lack of irregularities that returns the radar signal.

  8. Mapping ionospheric convection patterns to the magnetosphere

    NASA Astrophysics Data System (ADS)

    Maynard, Nelson C.; Denig, William F.; Burke, William J.

    1995-02-01

    While convection patterns in the high-latitude ionosphere are usually presented in a corotating frame of reference, those of the magnetosphere are given in inertial coordinates. In the corotating representation the convection throat, which is frequently associated with the cusp, opens between 1000 and 1100 MLT. Cusp precipitation, however, centers about noon. We find that transforming the convection patterns of Heppner and Maynard (1987) (hereinafter H-M) into inertial coordinates aligns the throat region with local noon. We present projections of the H-M patterns to the magnetosphere in both corotating and inertial coordinates using the magnetic field model of Tsyganenko (1989). In inertial coordinates the mapped H-M convection throat opens at noon. Consistent with predictions of the Rice convection model for magnetospheric electric fields late in the substorm cycle, only a small fraction of the equipotential contours penetrate to the subsolar region. This suggests that a significant portion of flux tube merging occurs on magnetic field lines whose equatorial mapping is on the flanks of the magnetosphere. Nonconjugacy between the mapping of H-M patterns for both positive and negative interplanetary magnetic field B(sub Y), especially in the 1400-1600 LT sector, may explain the B(sub Y) dependence of the electron precipitation 'hot spot' discovered by Evans (1985). A separate lobe cell is not required to explain the central, equipotential contours of the large convection cell.

  9. Estimating the Circulation and Net Plasma Loss from Ionospheric Outflow

    NASA Astrophysics Data System (ADS)

    Haaland, S.; Engwall, E.; Eriksson, A. I.; Nilsson, H.; Foerster, M.; Lybekk, B.; Svenes, K.; Pedersen, A.

    2010-12-01

    An important source of magnetospheric plasma is outflow from the terrestrial ionosphere. Low energy ions travel along the magnetic field lines and enter the magnetospheric lobes and are convected towards the tail plasma sheet. Results from Cluster indicate that the field aligned outflow velocity is sometimes much higher than the convection towards the central plasma sheet. A substantial amount of plasma therefore escape downtail without ever reaching the central plasma sheet. In this work, we use Cluster measurements of the ionospheric outflow and lobe convection velocities combined with a model of the magnetic field in an attempt to quantify the plasma loss for various magnetospheric conditions. The results show that both the circulation of plasma but also the tailward escape of ions increase significantly during disturbed magnetospheric conditions. For strong solar wind driving with a southward interplanetary magnetic field, also typically associated with high geomagnetic activity, most of the outflowing plasma are convected to the plasma sheet and recirculated. For periods with northward interplanetary magnetic field, the convection is nearly stagnant, whereas the outflow, although limited, still persist. During such conditions, the outflowing ions escape downtail and are lost into the solar wind.

  10. Multistation measurements of high-latitude ionospheric convection

    NASA Astrophysics Data System (ADS)

    Heelis, R. A.; Foster, J. C.; Holt, J.; de La Beaujardiere, O.

    1983-12-01

    Satellite and ground-based observations of the ionospheric drift velocity taken during a MITHRAS campaign have been combined to determine instantaneous pictures of the high-latitude convection pattern. These data, taken when the interplanetary magnetic field has a relatively stable southward/away orientation, show the existence of an asymmetric convection pattern under these conditions. A stability in the high latitude convection geometry can also be seen and changes in response to magnetic disturbances are inferred. Changes in the convection pattern as the interplanetary field turns northward possibly provide some information about the nature of the magnetosphere-solar wind interaction.

  11. Multistation measurements of high-latitude ionospheric convection

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.; Foster, J. C.; Holt, J.; De La Beaujardiere, O.

    1983-01-01

    Satellite and ground-based observations of the ionospheric drift velocity taken during a MITHRAS campaign have been combined to determine instantaneous pictures of the high-latitude convection pattern. These data, taken when the interplanetary magnetic field has a relatively stable southward/away orientation, show the existence of an asymmetric convection pattern under these conditions. A stability in the high latitude convection geometry can also be seen and changes in response to magnetic disturbances are inferred. Changes in the convection pattern as the interplanetary field turns northward possibly provide some information about the nature of the magnetosphere-solar wind interaction.

  12. Comparison between ionospheric convection vortices and the associated equivalent currents

    NASA Astrophysics Data System (ADS)

    Liang, J.; Benkevitch, L.; Sofko, G. J.; Koustov, A. V.

    2004-12-01

    The equivalent current pattern derived from CANOPUS, NRCAN/GSC and MACCS magnetometers has been compared with the ionospheric convection pattern observed by SuperDARN HF radars. The discrepancies between the equivalent convection (EQC) and the SuperDARN-observed convection (SDC) patterns are explained in terms of the effect of day-night photoionization conductance gradient and the coupling between field-aligned currents (FACs) and ionospheric conductances. In particular, the agreement between the EQC and SDC patterns is usually worse for a counterclockwise convection vortex than for a clockwise cell, but a consistent pattern of discrepancy for counterclockwise convection vortices has been found. We suggest that the discrepancies are due to a downward FAC-conductance coupling process. Since the counterclockwise vortices and clockwise vortices occur predominantly in the dawn and dusk sectors, respectively, in accordance with the usual 2-cell global convection pattern, the asymmetry between the EQC and SDC patterns for counterclockwise vortices and clockwise vortices would naturally lead to a dawn-dusk asymmetry as well. This is revealed by a global statistical study of the deviation of direction between the magnetic equivalent convection and the SuperDARN convection in different time sectors and latitudes. In the dawn sector, the statistical results reveal that, at lower latitudes, the EQC direction deviation is slightly counterclockwise with respect to the SDC direction, whereas the deviation is significantly clockwise at high latitudes. These deviations are consistent with the discrepancy pattern for counterclockwise convection vortices, as found in the individual vortex event studies.

  13. Effects of different convection models upon the high-latitude ionosphere

    NASA Technical Reports Server (NTRS)

    Rasmussen, C. E.; Schunk, R. W.; Sojka, J. J.

    1986-01-01

    The plasma convection models of Volland (1975) and Heelis (1982) are utilized to study the ionosphere. The parameters for the two models are evaluated. The two-cell convection models have similar total cross tail electric potential, diameter of the polar cap, and potential falloff rate outside the polar cap; however, they differ in maximum potential, and the electric field in the polar cap. The input parameters for the high-latitude ionospheric model are described. Two high-latitude ionospheric model runs were conducted and the data are compared in terms of electron density at and above the F 2 peak, attitude of the F 2 peak, ion temperature, and molecular-atomic ion transition height. The altitude dependence of electron density is analyzed using coherent scatter radar data. The data reveal differences between the two models in the height of the F 2 peak and in the ion temperature. The altitude values of the Heelis model are higher than the Volland model in the region where plasma is transported into the polar cap and lower in the region plasma is transported out of the polar cap; the Heelis model also produces an increase in ion temperature. It is noted that the ionosphere has a limited dependence upon the details of the convection models.

  14. Plasma convection in Neptune's magnetosphere

    NASA Technical Reports Server (NTRS)

    Selesnick, R. S.

    1990-01-01

    The magnetosphere of Neptune changes its magnetic configuration continuously as the planet rotates, leading to a strong modulation of the convection electric field. Even though the corotation speed is considerably larger, the modulation causes the small convection speed to have a cumulative effect, much like the acceleration of particles in a cyclotron. A model calculation shows that plasma on one side of the planet convects out of the magnetosphere in a few planetary rotations, while on the other side it convects slowly planetward. The observation of nitrogen ions from a Triton plasma torus may provide a critical test of the model.

  15. A three-dimensional diffusion/convection model of the large scale magnetic field in the Venus ionosphere

    NASA Technical Reports Server (NTRS)

    Luhmann, J. G.

    1988-01-01

    A three-dimensinal diffusion/convection model of the dayside Venus ionosphere magnetic field was developed on the basis of previously published one-dimensional diffusion/convection models, and assuming that the field and flow at the upper boundary (in the magnetic barrier) as well as the ionospheric plasma velocity are known. The results indicate that the low-altitude magnetosheath field draping may be distorted by the interaction with the ionosphere in such a manner that there is an apparent 'focusing' of the field toward the subsolar point, caused by the shear in the horizontal velocity between the magnetosheath and ionospheric flows. A comparison of published magnetic-field observations with the present results indicates that the simple nesting of external and internal velocity fields may be a good approximation to global plasma flows near Venus under normal conditions.

  16. Plasma interactions in the Martian Nightside Ionosphere

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Fowler, C. M.; Ergun, R.; Weber, T. D.; Andrews, D. J.; Morooka, M. W.; Delory, G. T.; Eriksson, A. I.; Mitchell, D. L.; McFadden, J. P.; Connerney, J. E. P.

    2015-12-01

    Based on measurements from a number of missions at Mars the nightside ionosphere is patchy. The new mission MAVEN dedicated to observe the upper atmosphere and the plasma interactions provides the first comprehensive observations of the low altitude nightside ionosphere. Observations show that at density gradients the plasma is unstable and significant wave power, heated/accelerated electrons, and heated ions are co-located. Below 300 km, thermal electrons (>3 eV) are observed at the gradients to low density regions. The nightside ionosphere below 180 km is thought to be maintained by electron impact ionization and therefore these regions with thermal electrons may be the primary energy source for the low altitude ionosphere. Outside of the low density regions the plasma is cold. These observations suggest that the wave heating might be the primary process in the Matrian nightside ionosphere. The characteristics of these regions associated with density gradients will be presented and discussed in this presentation.

  17. In situ observations of bifurcation of equatorial ionospheric plasma depletions

    SciTech Connect

    Aggson, T.L.; Pfaff, R.F.; Maynard, N.C.

    1996-03-01

    Vector electric field measurements from the San Marco D satellite are utilized to investigate the bifurcation of ionospheric plasma depletions (sometimes called {open_quotes}bubbles{close_quotes}) associated with nightside equatorial spread F. These depletions are identified by enhanced upward ExB convection in depleted plasma density channels in the nighttime equatorial ionosphere. The in situ determination of the bifurcation process is based on dc electric field measurements of the bipolar variation in the zonal flow, westward and eastward, as the eastbound satellite crosses isolated signatures of updrafting plasma depletion regions. The authors also present data in which more complicated regions of zonal velocity variations appear as the possible result of multiple bifurcations of updrafting equatorial plasma bubbles. 10 refs., 7 fig.

  18. Evidence for Gravity Wave Seeding of Convective Ionosphere Storms Initiated by Deep Troposphere Convection

    NASA Astrophysics Data System (ADS)

    Kelley, M. C.; Pfaff, R. F., Jr.; Dao, E. V.; Holzworth, R. H., II

    2014-12-01

    With the increase in solar activity, the Communications/Outage Forecast System satellite (C/NOFS) now goes below the F peak. As such, we now can study the development of Convective Ionospheric Storms (CIS) and, most importantly, large-scale seeding of the low growth-rate Rayleigh-Taylor (R-T) instability. Two mechanisms have been suggested for such seeding: the Collisional Kelvin-Helmholtz Instability (CKHI) and internal atmospheric gravity waves. A number of observations have shown that the spectrum of fully developed topside structures peaks at 600 km and extends to over 1000 km. These structures are exceedingly difficult to explain by CKHI. Here we show that sinusoidal plasma oscillations on the bottomside during daytime develop classical R-T structures on the nightside with the background 600 km structure still apparent. In two case studies, thunderstorm activity was observed east of the sinusoidal features in the two hours preceding the C/NOFS passes. Thus, we argue that convective tropospheric storms are a likely source of these sinusoidal features.

  19. Extension of convection modeling into the high-latitude ionosphere - Some theoretical difficulties

    NASA Astrophysics Data System (ADS)

    Wolf, R. A.; Spiro, R. W.; Rich, F. J.

    1991-09-01

    The Rice Convection Model (RCM) is extended and merged with empirical models so as to cover the entire high-latitude ionosphere with the aim of providing precipitation and electric field inputs for ionosphere and thermosphere modelers and producing a model in which the boundaries of the precipitation and electric field patterns maintain physically consistent relationships to each other. The computed auroral electron energy flux, plotted as a function of latitude, exhibited an exaggerated two-peak structure. When no floor was placed under the precipitation rate, the minimum between the two peaks was much too deep to be consistent with typical observations. The regions of excessively weak precipitation map to equatorial distances of 15-35 RE and thus to the regions of the plasma sheet that were not included in previous self-consistent convection calculations.

  20. Role of Ionospheric Plasmas in Earth's Magnetotail

    NASA Technical Reports Server (NTRS)

    Moore, Thomas E.

    2007-01-01

    This tutorial will summarize observations and theories indicating a prominent role of ionospheric plasma in the Earth's magnetotail. At the Global scale, I will argue that it is ionospheric plasma momentum and dynamic pressure that are responsible for the production of plasmoids, through the action of a transient near-Earth neutral or X-line, which serves to release excessive plasma pressure from the magnetotail field. Ionospheric plasma gains the momentum and energy to produce plasmoids and their related effects through its interaction with the solar wind, beginning at the dayside reconnection region and extending across the polar caps through the magnetotail lobes. This distant neutral line can be depicted as a feature much like that found in cometary magnetospheres, where disconnection limits the amount of IMF hung up on the cometary coma. On the other hand, the near-Earth neutral one can be seen as a feature unique to planets with an intrinsic magnetic field and internal source of plasma, the heating of which produces pressures too large to be restrained. Ionospheric plasmas also have other more local roles to play in the magnetotail. The circulation influences the composition of the plasma sheet, and the resultant wave environment, giving rise to reduced wave propagation speeds. Important heavy ion cyclotron resonances, and enhanced finite gyro-radius effects including non-adiabatic particle acceleration. At minimum, the presence of ionospheric plasma must influence the rate of reconnection via its enhanced mass density. Other non-MHD effects of ionospheric plasma presence are likely to be important but need much more investigation to be well understood. The MMS mission is designed to penetrate the subtle diffusion region physics that is involved, and its ability to observe ionospheric plasma involvement in reconnection will contribute significantly toward that goal.

  1. North-south asymmetries in magnetospheric and ionospheric plasma circulation

    NASA Astrophysics Data System (ADS)

    Haaland, S.; Foerster, M.; Laundal, K.; McCracken, K. G.; Maes, L.; Lybekk, B.; Pedersen, A.

    2015-12-01

    Interaction between the solar wind and the dayside terrestrial magnetopause causes a transfer of energy and momentum from the solar wind to the magnetosphere. Consequently, a large scale circulation - the Dungey cycle - is set up in the magnetosphere. Since the magnetosphere is magnetically connected to the ionosphere, a corresponding circulation of plasma is also set up in the high-latitude ionosphere. Influences from external drivers, in particular the orientation of the radial component of the interplanetary magnetic field as well as daily and seasonal variations in the Earth's tilt angle are known to set up temporal north-south asymmetries in the magnetospheric and ionospheric plasma circulation. There are also persistent north-south asymmetries, which cannot easily be explained by the influence of external drivers. In this presentation, we show examples of such asymmetries in ionospheric convection and asymmetries in magnetospheric lobe density, presumably related to hemispheric asymmetries in ion outflow. We infer that these persistent asymmetries are mainly caused by differences in the strength and configuration of the geomagnetic field between the Northern and Southern Hemispheres. Since the ionosphere is magnetically connected to the magnetosphere, this difference will also be reflected in the magnetosphere in the form of different feedback from the two hemispheres.

  2. Ionospheric convection during the magnetic storm of 20-21 March 1991

    NASA Technical Reports Server (NTRS)

    Taylor, J. R.; Yeoman, T. K.; Lester, M.; Buonsanto, M. J.; Scali, J. L.; Ruohoniemi, J. M.; Kelly, J. D.

    1994-01-01

    We report on the response of high-latitude ionospheric convection during the magnetic storm of March 20-21 1990. IMP-8 measurements of solar wind plasma and interplanetary magnetic field (IMF), ionospheric convection flow measurements from the Wick and Goose Bay coherent radars, EISCAT, Millstone Hill and Sondrestorm incoherent radars and three digisondes at Millstone Hill, Goose Bay and Qaanaaq are presented. Two intervals of particular interest have been indentified. The first starts with a storm sudden commencement at 2243 UT on March 20 and includes the ionospheric activity in the following 7 h. The response time of the ionospheric convection to the southward tuning of the IMF in the dusk to midnight local times is found to be approximately half that measured in a similar study at comparable local times during more normal solar wind conditions. A subsequent reconfiguration of the nightside convection pattern was also observed, although it was not possible to distinguish between effects due to possible changes in B(sub y) and effects due to substorm activity. The second interval, 1200-2100 UT 21 March 1990, included a southward turning of the IMF which resulted in the B(sub z) component becoming -10 nT. The response time on the dayside to this change in the IMF at the magnetopause was approximately 15 min to 30 min which is a factor of approximately 2 greater than those previously measured at higher latitudes. A movement of the nightside flow reversal, possibly driven by current systems associated with the substorm expansion phases, was observed, implying that the nightside convection pattern can be dominated by substorm activity.

  3. Active plasma antenna in the Earth's ionosphere

    NASA Astrophysics Data System (ADS)

    Chugunov, Yu. V.; Markov, G. A.

    2001-11-01

    We discuss a new method for controlled stimulation of global perturbations in the Earth's ionosphere and magnetosphere and new possibilities of diagnostics of the wave-particle interaction in the ionospheric and magnetospheric plasma. The method is based on the excitation of an RF plasma-wave discharge in the electromagnetic field of a rocket-borne dipole antenna in the lower oblique-resonance frequency band. The evolution of the discharge leads to the creation of strong local disturbances at ionospheric altitudes in the form of magnetic-field-aligned plasma irregularities with controllable properties. The method was verified in 6 rocket flights at middle and polar latitudes. We review the results of these experiments, focusing considerable attention on those which show significant plasma disturbances in the magnetic flux tube where the rocket is located and which demonstrate the diversity of capabilities of this method. In particular, it is shown that a deep (by an order of magnitude) modulation of energetic (>=40keV) precipitating electrons is available. We have demonstrated that a modulated discharge in the ionosphere can operate as an active plasma antenna. A generation of ``echo'' signals at the discharge modulation frequency and an excitation of the ionospheric Alfvén resonator in the PC band have also been observed. Along with numerous scientific advantages, the method has appeared to be energy-effective and low-cost, which makes it very promising for ionospheric and magnetospheric studies as well as for various practical applications.

  4. The ionospheres and plasma tails of comets

    NASA Technical Reports Server (NTRS)

    Mendis, D. A.; Ip, W.-H.

    1977-01-01

    The paper reviews the current state of knowledge about cometary plasma (type I) tails and ionospheres. Observational statistics for type I tails are examined along with spectroscopic observations of plasma tails, identified ion species in such tails, and the morphology of cometary plasma tails and ionospheres. Evidence for a strong interaction between comets and the solar wind is evaluated on the basis of observations of plasma-tail orientations, large accelerations of tail structures, and correlations between disturbances in type I tails and solar-wind or geomagnetic disturbances. The use of comets as solar-wind probes is discussed, the nature of comet-solar-wind interactions is investigated, and ionization sources for cometary gases are considered. Hydrodynamic models of comet-solar-wind interaction are summarized, and the structure and ion chemistry of cometary ionospheres are studied. Observations suggesting that significant magnetic fields are associated with comets are briefly reviewed and interpreted.

  5. Dawn-dusk asymmetry of SI-induced transient ionospheric convection

    NASA Astrophysics Data System (ADS)

    Hori, T.; Fujita, S.; Shinbori, A.; Nishitani, N.

    2015-12-01

    A statistical study using a large data set of Super Dual Auroral Radar Network (SuperDARN) observations is conducted for transient ionospheric plasma flows associated with sudden impulses (SI) recorded on ground magnetic field. The global structure of twin vortex-like ionospheric flows is found to be consistent with the twin vortices of ionospheric Hall current deduced by the past geomagnetic field observations. An interesting feature, which is focused on in this study, is that the flow structures show a dawn-dusk asymmetry. One is the difference in flow magnitude of the lower-latitude portion of the flow vortices, which is much clearer for positive SIs. The sunward flow perturbation on the dusk side is significantly larger than that on dawn side. A set of global MHD simulation runs performed by the present study have successfully reproduced the similar asymmetry of the lower-latitude transient flows. The result suggests that ionospheric conductance plays an important role in reproducing this dawn-dusk asymmetry. Another dawn-dusk asymmetry is found for the higher-latitude portion of flow vortices in which a larger flow appears either of dawn or dusk depending on the combination of the polarity of SI and IMF-By. Detailed statistics of the SuperDARN observations reveals that the dawn-dusk asymmetry of flow vortices due to IMF-By appear more clearly during negative SIs, while the flow vortices are more or less symmetric during positive SIs, regardless of IMF-By polarity. On the basis of the upstream observations, we suggest that this particular dawn-dusk asymmetry is caused by the interaction between the pre-existing round convection cell and a pair of the transient convection vortices associated with SIs. The combination of the two convection cell systems has also been reproduced by our MHD simulations.

  6. Venus' nighttime horizontal plasma flow, 'magnetic congestion', and ionospheric hole production

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Mayr, H. G.; Curtis, S. A.; Taylor, H. A., Jr.

    1983-01-01

    A simple rectilinear, two-dimensional MHD model is used to investigate the effects of field-aligned plasma loss and cooling on a dense plasma convecting across a weak magnetic field, in order to illumine the Venus nighttime phenomena of horizontal plasma flow, magnetic congestion and ionospheric hole production. By parameterizing field-aligned variations and explicitly solving for cross magnetic field variations, it is shown that the abrupt horizontal enhancements of the vertical magnetic field, as well as sudden decreases of the plasma density to very low values (which are characteristic of ionospheric holes), can be produced in the presence of field-aligned losses.

  7. A three-dimensional diffusion/convection model of the large scale magnetic field in the Venus ionosphere

    SciTech Connect

    Luhmann, J.G. )

    1988-06-01

    An appreciation of how large-scale magnetic fields can be maintained in the subsolar Venus ionosphere by the solar wind interaction was previously obtained with one-dimensional diffusion/convection numerical models. Here, the solution of the diffusion/convection or dynamo equation for the ionospheric field is generalized to three dimensions under the assumption that the field and flow at the upper boundary (in the magnetic barrier) is known from a previous gas dynamic model, and that the ionospheric plasma velocity is known. The latter is given by the combination of the antisunward convection inferred from measurements, and the downward drift calculated from the observed vertical thermal pressure gradient. The results suggest that the low-altitude magnetosheath field draping may be distorted by the interaction with the ionosphere in such a manner that there is an apparent focusing of the field toward the subsolar point. Although the model resolution is too course to resolve the magnetic belt, an ionospheric field is produced that is strongest and parallel to the overlying field in the subsolar region, as is observed.

  8. Observations of ionospheric convection vortices - Signatures of momentum transfer

    NASA Technical Reports Server (NTRS)

    Mchenry, M. A.; Clauer, C. R.; Friis-Christensen, E.; Kelly, J. D.

    1988-01-01

    Several classes of traveling vortices in the dayside ionospheric flow have been detected and tracked using the Greenland magnetometer chain. One class observed during quiet times consists of a continuous series of vortices moving generally antisunward for several hours at a time. Assuming each vortex to be the convection pattern produced by a small field aligned current moving across the ionosphere, the amount of field aligned current was found by fitting a modeled ground magnetic signature to measurements from the chain of magnetometers. The calculated field aligned current is seen to be steady for each vortex and neighboring vortices have currents of opposite sign. Low altitude DMSP observations indicate the vortices are on field lines which map to the inner edge of the low latitude boundary layer. Because the vortices are conjugate to the boundary layer, repeat in a regular fashion and travel antisunward, it is argued that this class of vortices is caused by surface waves at the magnetopause. No strong correlations between field aligned current strength and solar wind density, velocity, or Bz is found.

  9. Ionospheric plasma dynamics and instability causedby upward currents above thunderstorms

    NASA Astrophysics Data System (ADS)

    Kuo, C. L.; Lee, L. C.

    2015-12-01

    Thunderstorms are electric generators, which drive currents upwardly into the ionosphere. In thispaper, we examine the effects of thunderstorm upward current on the ionosphere. We use a thunderstormmodel to calculate the three-dimensional current flows in the atmosphere and to simulate the upward currentabove the thunderstormwith the tripole-charge structure. The upward current flows into the ionosphere, whilethe associated electric field causes the plasma E × B motion. The caused plasma motion redistributes theplasma density, leading to ionospheric density variations. In the nighttime ionosphere, the E × B motion mayalso cause the formation of plasma bubbles.

  10. Interplanetary magnetic field effects on high latitude ionospheric convection

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.

    1985-01-01

    Relations between the electric field and the electric current in the ionosphere can be established on the basis of a system of mathematical and physical equations provided by the equations of current continuity and Ohm's law. For this reason, much of the synthesis of electric field and plasma velocity data in the F-region is made with the aid of similar data sets derived from field-aligned current and horizontal current measurements. During the past decade, the development of a self-consistent picture of the distribution and behavior of these measurements has proceeded almost in parallel. The present paper is concerned with the picture as it applies to the electric field and plasma drift velocity and its dependence on the interplanetary magnetic field. Attention is given to the southward interplanetary magnetic field and the northward interplanetary magnetic field.

  11. Investigation of Solar Wind Coupling to the High-Latitude Ionospheric Reverse Convection Electric Field during Large Positive IMF Bz

    NASA Astrophysics Data System (ADS)

    Clauer, C. R.; Deshpande, K.; Xu, Z.; Hartinger, M.; Weimer, D. R.; Nicolls, M. J.

    2015-12-01

    An empirical determination of the coupling function between the solar wind dynamo electric field and the high latitude ionospheric electric field is possible using the Weiner filter technique. We investigate the response of the high latitude reverse convection electric field measured by the Resolute Incoherent Scatter Radar (RISR) during periods of large northward IMF for two CME-related events 12-13 September 2014 and 22 - 23 June 2015. The technique provides the most general linear coupling function including frequency response and time delays. We find that the solar wind is strongly coupled to the high latitude reverse convection electric field. We discuss the details of this coupling as it relates to various parameters that may influence the coupling efficiency, such as solar wind mach number, plasma beta, ionospheric Pederson conductivity, etc.

  12. Testing Plasma Physics in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Konstantinos

    TESTING PLASMA PHYSICS IN THE IONOSPHERE K. Papadopoulos University of Maryland College Park, MD 20742 Ionospheric heaters supplemented by ground and space based diagnostic instruments, such as radars, optical cameras and photometers, HF/VLF/ELF/ULF receivers and magnetometers, radio beacons, riometers and ionosondes have for a long time being used to conduct plasma physics, geophysical and radio science investigations. The latest entry to ionospheric heating, the HF transmitter associated with the High Frequency Active Ionospheric Research Program (HAARP), was completed in February 2007. The transmitter consists of 180 antenna elements spanning 30.6 acres and can radiate 3.6 MW of HF power in the 2.8-10.0 MHz frequency range. With increasing frequency the beam-width varies from 15-5 degrees, corresponding to 20-30 dB gain and resulting in Effective Radiating Power (ERP) between .36 - 4.0 GW. The antenna can point to any direction in a cone of 30 degrees from the vertical, with a reposition time of 15 degrees in 15 microseconds resulting in super-luminous scanning speeds. The transmitter can synthesize essentially any desired waveform within the regulatory allowed bandwidth in linear and circular polarization. These capabilities far exceed those of previous ionospheric heaters and allow for new frontier research in plasma physics, geophysics and radio science. Following a brief discussion of the relationship of the new capabilities of the facility with thresholds of physical processes that could not be achieved previously, the presentation will discuss recent results in the areas of ULF/ELF/VLF generation and propagation and wave-particle interactions in the magnetosphere acquired with the completed facility. The presentation will conclude with a detailed discussion of possible frontier science experiments in the areas of Langmuir turbulence, parametric instabilities, electron acceleration, optical emissions and field aligned striations and duct generation, made

  13. Estimating the capture and loss of cold plasma from ionospheric outflow

    NASA Astrophysics Data System (ADS)

    Haaland, S.; Eriksson, A.; Engwall, E.; Lybekk, B.; Nilsson, H.; Pedersen, A.; Svenes, K.; André, M.; Förster, M.; Li, K.; Johnsen, C.; Østgaard, N.

    2012-07-01

    An important source of magnetospheric plasma is cold plasma from the terrestrial ionosphere. Low energy ions travel along the magnetic field lines and enter the magnetospheric lobes where they are convected toward the tail plasma sheet. Recent observations indicate that the field aligned ion outflow velocity is sometimes much higher than the convection toward the central plasma sheet. A substantial amount of plasma therefore escapes downtail without ever reaching the central plasma sheet. In this work, we use Cluster measurements of cold plasma outflow and lobe convection velocities combined with models of the magnetic field in an attempt to determine the fate of the outflowing ions and to quantify the amount of plasma lost downtail. The results show that both the circulation of plasma and the direct tailward escape of ions varies significantly with magnetospheric conditions. For strong solar wind driving with a southward interplanetary magnetic field, also typically associated with high geomagnetic activity, most of the outflowing plasma is convected to the plasma sheet and recirculated. For periods with northward interplanetary magnetic field, the convection is nearly stagnant, whereas the outflow, although limited, still persists. The dominant part of the outflowing ions escape downtail and are directly lost into the solar wind under such conditions.

  14. Diffusion of rotating inhomogeneities in ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Erukhimov, L. M.; Myasnikov, E. N.

    1998-02-01

    We consider the problem of generation of small-scale quasistatic electric fields that can lead to establishment of the bipolar regime of inhomogeneity relaxation observed in experimental studies of the properties of an artificial turbulence excited in the upper ionosphere by high-power shortwave radio emission [1 8], which is slower than the regime of unipolar diffusion of quasineutral fluctuations of density in a homogeneous strongly magnetized plasma [9 11]. We show that necessary conditions for the existence of this mode are disruption of the symmetry of the initial disturbance in the plasma density with respect to the direction of the field ěc B_0 and its differential rotation with the drift frequency in the plane orthogonal to ěc B_0 . Assuming that the initial disturbance of the plasma has the form of a plane wave whose wave vector ěc k makes an angle θ = k_allel /k_ bot ≪ 1 with the normal to ěc B_0 , we obtain an expression for the drift frequency and study the relations between the fluctuational electric and magnetic fields and the drift velocity of the disturbed plasma in, the linear approximation. We discuss the properties of the nonlinear solution, which, in particular, can describe generation of small-scale plasma inhomogeneities that have a helical structure in the plane orthogonal to ěc B_0 . The phenomenon of frequency broadening of the Doppler spectra of signals of field-aligned SW and USW scattering observed in the case of field-aligned scattering of short and ultrashort radio waves by artificial ionospheric inhomogeneities [4 7] is interpreted.

  15. Plasma bubble phenomenon in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Sidorova, L. N.

    There are the indications that plasma bubbles/flux tube aligned plasma density depletions, produced by Rayleigh-Taylor instability at the bottomside of ionosphere, could rise up to the topside ionosphere and plasmasphere. Maruyama and Matuura [Maruyama, T., Matuura, N. Longitudinal variability of annual changes in activity of equatorial spread-F and plasma bubbles. J. Geophys. Res. 89(A12), 10903-10912, 1984.], using ISS-b satellite data for the high solar activity period, 1978-1979, have seen the plasma bubbles over equator at 1100 km altitudes in 46 cases in 1700 passes. That is ˜3% only. However, there is distinctly another picture in He + density depletions (subtroughs) according to the ISS-b data for the same period. He + density subtroughs were observed in the topside ionosphere over equatorial and low-latitudinal regions ( L ˜ 1.3-3) in 11% of the cases [Karpachev, A.T., Sidorova, L.N. Occurrence probability of the light ion trough and subtrough in He + density on season and local time. Adv. Space Res. 29, 999-108, 2002; Sidorova, L.N., He + density topside modeling based on ISS-b satellite data. Adv. Space Res. 33, 850-854, 2004.]. We have carried out a statistical study of the He + density subtrough characteristics. The subtrough depth (depletion value) as function of local time (evening-night hours) was compared with the vertical plasma drift velocity variations, obtained for the same periods from the AE-E satellite and IS radar (Jicamarca) data. Striking similarity in development dynamics is revealed for the different seasons. It is noted also that the He + density subtroughs are mostly observed in the evening-night sector (18-05 LT) from October till May, which is very similar to the peculiarities of the equatorial spread-F (ESF), usually associated with plasma bubbles. The monthly mean He + density subtrough occurrence probability, plotted in local time versus month, was compared with the similar plots for ESF occurrence probability derived by Abdu

  16. Ionospheric Plasma Structures Observed by FORMOSAT-3/COSMIC

    NASA Astrophysics Data System (ADS)

    Lin, Charles C. H.; Chen, Chia-Hung; Thampi, Smitha V.; Liu, Jann-Yenq; Liu, C. H.

    The GPS Occultation eXperiment (GOX) on board the FORMOSAT-3/COSMIC (F3/C) has provided large amount of the ionospheric electron density soundings since the satellite con-stellation was launched in April 2006. By averaging the electron density profiles distributed global-wide during one-or two-month period, three-dimensional ionospheric electron density maps can be constructed for studying quiet-time ionosphere climatology. Through analysis of the 3-D ionospheric maps during the four years period of the mission, the occultation observa-tions have shown further details of ionospheric plasma structures, such as, the wave-signature of the equatorial ionosphere, the mid-latitude summer nighttime anomaly (MSNA) and the plasma depletion bay (PDB). Additional to the GOX, two other instruments, the tiny iono-spheric photometer (TIP) and the tri-band beacon (TBB), on board the constellation provide more aspects of these plasma structures. In this presentation, we summarize the ionospheric plasma structures observed by the constellation mission, as well as the important details of the plasma structures unveiled by the constellation for better understandings the associated formation mechanism.

  17. Testing Predictions of the Ionospheric Convection from the Expanding/Contracting Polar Cap Paradigm

    NASA Astrophysics Data System (ADS)

    Walach, M. T.; Milan, S. E.; Yeoman, T. K.; Hairston, M. R.; Hubert, B. A.

    2015-12-01

    The expanding/contracting polar cap (ECPC) paradigm, or the time-dependent Dungey cycle, provides a theoretical framework for understanding solar wind-magnetosphere-ionosphere coupling. The ECPC describes the relationship between magnetopause reconnection and substorm growth phase, magnetotail reconnection and substorm expansion phase, associated changes in auroral morphology, and ionospheric convective motions. Despite the many successes of the model, there has yet to be a rigorous test of the predictions made regarding ionospheric convection, which remains a final hurdle for the validation of the ECPC. In this study we undertake a comparison of ionospheric convection, as measured by ion driftmeters on board DMSP (Defense Meteorological Satellite Program) satellites, with motions predicted by a theoretical model (Milan, 2013). The model is coupled to measurements of changes in the size of the polar cap made using global auroral imagery from the IMAGE FUV (Imager for Magnetopause to Aurora Global Exploration Far Ultraviolet) instrument, as well as the dayside reconnection rate, calculated using the OMNI dataset. The results show that we can largely predict the magnitudes of ionospheric convection flows using the context of our understanding of magnetic reconnection at the magnetopause and in the magnetotail.

  18. Ionospheric convection inferred from interplanetary magnetic field-dependent Birkeland currents

    NASA Technical Reports Server (NTRS)

    Rasmussen, C. E.; Schunk, R. W.

    1988-01-01

    Computer simulations of ionospheric convection have been performed, combining empirical models of Birkeland currents with a model of ionospheric conductivity in order to investigate IMF-dependent convection characteristics. Birkeland currents representing conditions in the northern polar cap of the negative IMF By component are used. Two possibilities are considered: (1) the morning cell shifting into the polar cap as the IMF turns northward, and this cell and a distorted evening cell providing for sunward flow in the polar cap; and (2) the existence of a three-cell pattern when the IMF is strongly northward.

  19. Inertial Alfven-Wave-Driven Convective Cells in Low-Density Plasmas

    SciTech Connect

    Pokhotelov, O.A.; Onishchenko, O.G.; Sagdeev, R.Z.; Stenflo, L.; Balikhin, M.A.

    2005-10-15

    The parametric interaction of inertial Alfven waves with large-scale convective cells in a low-density plasma is investigated. It is shown that, in plasmas where the Alfven velocity is comparable to or exceeds the speed of light, the parametric interaction is substantially suppressed. A compact expression for the optimal scale and instability growth rate of the fastest growing mode is obtained. The relevance of our theory to spacecraft measurements in the Earth's ionosphere is discussed.

  20. Cassini Measurements of Cold Plasma in the Ionosphere of Titan

    NASA Astrophysics Data System (ADS)

    Wahlund, J.-E.; Boström, R.; Gustafsson, G.; Gurnett, D. A.; Kurth, W. S.; Pedersen, A.; Averkamp, T. F.; Hospodarsky, G. B.; Persoon, A. M.; Canu, P.; Neubauer, F. M.; Dougherty, M. K.; Eriksson, A. I.; Morooka, M. W.; Gill, R.; André, M.; Eliasson, L.; Müller-Wodarg, I.

    2005-05-01

    The Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe (LP) sensor observed the cold plasma environment around Titan during the first two flybys. The data show that conditions in Saturn's magnetosphere affect the structure and dynamics deep in the ionosphere of Titan. The maximum measured ionospheric electron number density reached 3800 per cubic centimeter near closest approach, and a complex chemistry was indicated. The electron temperature profiles are consistent with electron heat conduction from the hotter Titan wake. The ionospheric escape flux was estimated to be 1025 ions per second.

  1. Direct observations of the full Dungey convection cycle in the polar ionosphere for southward interplanetary magnetic field conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Q.-H.; Lockwood, M.; Foster, J. C.; Zhang, S.-R.; Zhang, B.-C.; McCrea, I. W.; Moen, J.; Lester, M.; Ruohoniemi, J. M.

    2015-06-01

    Tracking the formation and full evolution of polar cap ionization patches in the polar ionosphere, we directly observe the full Dungey convection cycle for southward interplanetary magnetic field (IMF) conditions. This enables us to study how the Dungey cycle influences the patches' evolution. The patches were initially segmented from the dayside storm enhanced density plume at the equatorward edge of the cusp, by the expansion and contraction of the polar cap boundary due to pulsed dayside magnetopause reconnection, as indicated by in situ Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. Convection led to the patches entering the polar cap and being transported antisunward, while being continuously monitored by the globally distributed arrays of GPS receivers and Super Dual Auroral Radar Network radars. Changes in convection over time resulted in the patches following a range of trajectories, each of which differed somewhat from the classical twin-cell convection streamlines. Pulsed nightside reconnection, occurring as part of the magnetospheric substorm cycle, modulated the exit of the patches from the polar cap, as confirmed by coordinated observations of the magnetometer at Tromsø and European Incoherent Scatter Tromsø UHF radar. After exiting the polar cap, the patches broke up into a number of plasma blobs and returned sunward in the auroral return flow of the dawn and/or dusk convection cell. The full circulation time was about 3 h.

  2. Current convective instability in detached divertor plasma

    NASA Astrophysics Data System (ADS)

    Krasheninnikov, S. I.; Smolyakov, A. I.

    2016-09-01

    The asymmetry of inner and outer divertors, which cause the inner divertor to detach first, while the outer one is still attached, results in the large temperature difference between the vicinities of inner and outer targets and the onset of large electric potential drop through detached plasma of the inner divertor. A large potential drop along with the inhomogeneity of the resistivity of detached plasma across the divertor leg drives the current convective instability in the inner divertor and subsequent fluctuations of radiation loss similar to that observed in experiments. The estimates of the frequency of plasma parameter fluctuations due to the current convective instability are in a reasonable agreement with experimental data. Once the outer divertor also detaches, the temperature difference between the vicinities of inner and outer targets disappears, and the driving force for the current convective instability, and resulting oscillations of radiation loss, vanishes. This feature is indeed observed in experiments.

  3. Ionospheric physics

    SciTech Connect

    Sojka, J.J. )

    1991-01-01

    Advances in all areas of ionospheric research are reviewed for the 1987-1990 time period. Consideration is given to the equatorial ionosphere, the midlatitude ionosphere and plasmasphere, the auroral ionosphere, the polar ionosphere and polar wind, ionospheric electrodynamic inputs, plasma waves and irregularities, active experiments, ionospheric forecasting, and coupling the ionosphere with other regions.

  4. Radar studies of midlatitude ionospheric plasma drifts

    NASA Astrophysics Data System (ADS)

    Scherliess, L.; Fejer, B. G.; Holt, J.; Goncharenko, L.; Amory-Mazaudier, C.; Buonsanto, M. J.

    2001-02-01

    We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional E×B drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled as a function of the time history of the auroral electrojet indices. Our results illustrate the evolution of the disturbance drifts driven by the combined effects of prompt penetration and longer lasting perturbation electric fields. The meridional electrodynamic disturbance drifts have largest amplitudes in the midnight-noon sector. The zonal drifts are predominantly westward, with largest amplitudes in the dusk-midnight sector and, following a decrease in the high-latitude convection, they decay more slowly than the meridional drifts. The prompt penetration and steady state zonal disturbance drifts derived from radar measurements are in good agreement with results obtained from both the ion drift meter data on board the Dynamics Explorer 2 (DE 2) satellite and from the Rice Convection Model.

  5. Effect of high-latitude ionospheric convection on Sun-aligned polar caps

    NASA Technical Reports Server (NTRS)

    Sojka, J. J.; Zhu, L.; Crain, D. J.; Schunk, R. W.

    1994-01-01

    A coupled magnetospheric-ionospheric (M-I) magnetohydrodynamic (MHD) model has been used to simulate the formation of Sun-aligned polar cap arcs for a variety of interplanetary magnetic field (IMF) dependent polar cap convection fields. The formation process involves launching an Alfven shear wave from the magnetosphere to the ionosphere where the ionospheric conductance can react self-consistently to changes in the upward currents. We assume that the initial Alfven shear wave is the result of solar wind-magnetosphere interactions. The simulations show how the E region density is affected by the changes in the electron precipitation that are associated with the upward currents. These changes in conductance lead to both a modified Alfven wave reflection at the ionosphere and the generation of secondary Alfven waves in the ionosphere. The ensuing bouncing of the Alfven waves between the ionosphere and magnetosphere is followed until an asymptotic solution is obtained. At the magnetosphere the Alfven waves reflect at a fixed boundary. The coupled M-I Sun-aligned polar cap arc model of Zhu et al.(1993a) is used to carry out the simulations. This study focuses on the dependence of the polar cap arc formation on the background (global) convection pattern. Since the polar cap arcs occur for northward and strong B(sub y) IMF conditions, a variety of background convection patterns can exist when the arcs are present. The study shows that polar cap arcs can be formed for all these convection patterns; however, the arc features are dramatically different for the different patterns. For weak sunward convection a relatively confined single pair of current sheets is associated with the imposed Alfven shear wave structure. However, when the electric field exceeds a threshold, the arc structure intensifies, and the conductance increases as does the local Joule heating rate. These increases are faster than a linear dependence on the background electric field strength. Furthermore

  6. Evolution of high latitude ionospheric convection associated with substorms: Multiple radar observations

    NASA Astrophysics Data System (ADS)

    Zou, Shasha

    The work presented in this dissertation concerns evolution of the high latitude ionospheric convection and the relevant current systems associated with substorms, with emphasize on these features near the nightside Harang reversal region. Three different types of radars, including the Super Dual Auroral Radar Network (SuperDARN) coherent-scatter radars, the new advanced modular incoherent-scatter radar at Poker Flat (PFISR), and the Sondrestrom incoherent-scatter radar (ISR), have been utilized. Observations from those radars, together with those from complementary instruments, including satellites and other ground-based instruments, have revealed fundamental new understand of the ionospheric electrodynamic properties associated with substorms. By using the SuperDARN and the PFISR radars, we found that the auroral activity at substorm onset is located in the center of the Harang reversal, which represents a key region in the magnetospheric and ionospheric convection and is part of the Region 2 system. We have also shown that nightside convection flows exhibit repeatable, distinct variations at different locations relative to the substorm-related auroral activity. Taking advantage of the simultaneous flow and ionization measurements from PFISR, a current closure relation has been found between the Region 2 and the substorm field-aligned current systems. These observations demonstrate a strong coupling between the Region 2 system and the substorm dynamics. This study sheds new light on the substorm-related magnetosphere-ionosphere coupling and contributes to the building of a holistic picture of the substorm dynamics. The third radar has been used to study the dayside ionospheric convection response to the external soar wind and IMF driving and its role in substorm dynamics. The results have been applied to study substorm triggering and in the future could be used to study the relation between the external driving and the formation of the Harang reversal.

  7. Experimental studies of ionospheric irregularities and related plasma processes

    NASA Technical Reports Server (NTRS)

    Baker, Kay D.

    1992-01-01

    Utah State University (USU) continued its program of measuring and interpreting electron density and its variations in a variety of ionospheric conditions with the Experimental Studies of Ionospheric Irregularities and Related Plasma Processes program. The program represented a nearly ten year effort to provide key measurements of electron density and its fluctuations using sounding rockets. The program also involved the joint interpretation of the results in terms of ionospheric processes. A complete campaign summary and a brief description of the major rocket campaigns are also included.

  8. The INAF/IAPS Plasma Chamber for ionospheric simulation experiment

    NASA Astrophysics Data System (ADS)

    Diego, Piero

    2016-04-01

    The plasma chamber is particularly suitable to perform studies for the following applications: - plasma compatibility and functional tests on payloads envisioned to operate in the ionosphere (e.g. sensors onboard satellites, exposed to the external plasma environment); - calibration/testing of plasma diagnostic sensors; - characterization and compatibility tests on components for space applications (e.g. optical elements, harness, satellite paints, photo-voltaic cells, etc.); - experiments on satellite charging in a space plasma environment; - tests on active experiments which use ion, electron or plasma sources (ion thrusters, hollow cathodes, field effect emitters, plasma contactors, etc.); - possible studies relevant to fundamental space plasma physics. The facility consists of a large volume vacuum tank (a cylinder of length 4.5 m and diameter 1.7 m) equipped with a Kaufman type plasma source, operating with Argon gas, capable to generate a plasma beam with parameters (i.e. density and electron temperature) close to the values encountered in the ionosphere at F layer altitudes. The plasma beam (A+ ions and electrons) is accelerated into the chamber at a velocity that reproduces the relative motion between an orbiting satellite and the ionosphere (≈ 8 km/s). This feature, in particular, allows laboratory simulations of the actual compression and depletion phenomena which take place in the ram and wake regions around satellites moving through the ionosphere. The reproduced plasma environment is monitored using Langmuir Probes (LP) and Retarding Potential Analyzers (RPA). These sensors can be automatically moved within the experimental space using a sled mechanism. Such a feature allows the acquisition of the plasma parameters all around the space payload installed into the chamber for testing. The facility is currently in use to test the payloads of CSES satellite (Chinese Seismic Electromagnetic Satellite) devoted to plasma parameters and electric field

  9. Plasma effects of active ion beam injections in the ionosphere at rocket altitudes

    NASA Technical Reports Server (NTRS)

    Arnoldy, R. L.; Cahill, L. J., Jr.; Kintner, P. M.; Moore, T. E.; Pollock, C. J.

    1992-01-01

    Data from ARCS rocket ion beam injection experiments are primarily discussed. There are three results from this series of active experiments that are of particular interest in space plasma physics. These are the transverse acceleration of ambient ions in the large beam volume, the scattering of beam ions near the release payload, and the possible acceleration of electrons very close to the plasma generator which produce intense high frequency waves. The ability of 100 ma ion beam injections into the upper E and F regions of the ionosphere to produce these phenomena appear to be related solely to the process by which the plasma release payload and the ion beam are neutralized. Since the electrons in the plasma release do not convect with the plasma ions, the neutralization of both the payload and beam must be accomplished by large field-aligned currents (milliamperes/square meter) which are very unstable to wave growth of various modes.

  10. Hemispheric Asymmetry of Ionospheric Convection and Joule Heating and Its Impact on the Thermospher

    NASA Astrophysics Data System (ADS)

    Lu, G.

    2014-12-01

    The Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure has proved to be a very useful tool to estimate the large-scale simultaneous distributions of ionospheric conductance, electric potential, and other related quantities by combining simultaneous measurements from satellites, radars, and ground magnetometers. In this paper we apply the AMIE procedure to compare the high-latitude ionospheric convection and Joule heating patterns between the northern and southern hemispheres and to investigate how the hemispheric asymmetry varies with different solar wind and IMF conditions. We also investigate the impact of the asymmetric high-latitude magnetospheric forcing on themospheric dynamics based on the coupled AMIE-TIMEGCM simulations as well as through intercomparison with observations.

  11. Average patterns of precipitation and plasma flow in the plasma sheet flux tubes during steady magnetospheric convection

    NASA Technical Reports Server (NTRS)

    Sergeev, V. A.; Lennartsson, W.; Pellinen, R.; Vallinkoski, M.; Fedorova, N. I.

    1990-01-01

    Average patterns of plasma drifts and auroral precipitation in the nightside auroral zone were constructed during a steady magnetospheric convection (SMC) event on February 19, 1978. By comparing these patterns with the measurements in the midtail plasma sheet made by ISEE-1, and using the corresponding magnetic field model, the following features are inferred: (1) the concentration of the earthward convection in the midnight portion of the plasma sheet (convection jet); (2) the depleted plasma energy content of the flux tubes in the convection jet region; and (3) the Region-1 field-aligned currents generated in the midtail plasma sheet. It is argued that these three elements are mutually consistent features appearing in the process of ionosphere-magnetosphere interaction during SMC periods. These configurational characteristics resemble the corresponding features of substorm expansions (enhanced convection and 'dipolarized' magnetic field within the substorm current wedge) and appear to play the same role in regulating the plasma flow in the flux tubes connected to the plasma sheet.

  12. Transpolar and field-aligned ionospheric currents during polar convection bay events.

    NASA Astrophysics Data System (ADS)

    Stauning, Peter; Troshichev, Oleg

    Transpolar ionospheric currents and the related auroral field-aligned currents have been exam-ined using ground based magnetic observations supplemented by data from the polar orbiting Oersted and CHAMP satellites for a number of strong and steady polar convection bay events. The convection patterns have been derived from ground-based magnetic observations and the strength of the convection intensities have been characterized by the Polar Cap (PC) index. This group of steady events comprises the so-called "saw-tooth" events of recurrent disturbances occurring during strong and steady forcing of the magnetosphere by the solar wind. During such steady solar wind conditions the magnetic bay-related depressions and enhancements of polar cap convection intensities are more pronounced than during average substorm conditions. When adjusted for the varying convection direction and level the disturbance patterns are re-markably similar during sequences of these events and provide the basis for a detailed study, which shall be presented, of the spatial and temporal development of related ionospheric hori-zontal and field-aligned currents estimated both from ground and from satellite observations.

  13. Relationship of solar wind parameters to continuous, dayside, high latitude traveling ionospheric convection vortices

    NASA Technical Reports Server (NTRS)

    Mchenry, Mark A.; Clauer, C. Robert; Friis-Christensen, Eigil

    1990-01-01

    The results of a statistical study of the occurrence of steady traveling ionospheric convection vortices are presented. The upstream solar wind parameters observed by the IMP 8 spacecraft are studied as well. It is suggested that this class of pulsations is most likely to be detected post local noon and when the solar wind speed is low. A correlation between the frequency of dayside pulsations and the solar wind speed is found.

  14. Effect of finite blob size on the current convective instability in the auroral ionosphere. Memorandum report

    SciTech Connect

    Huba, J.D.; Chaturvedi, P.K.

    1986-04-11

    It has been suggested that the current convective instability may be responsible for the structuring, i.e., generation of density irregularities, of density enhancements (known as blobs) in the auroral ionosphere. However, previous theories have neglected the finite extent of the blob along the geomagnetic field. In this paper, a nonlocal theory of the current convective instability is developed, which considers the finite extent of an ionospheric blob parallel to the geomagnetic field. It was found that the growth rate of the instability can be substantially reduced in the finite-sized blob case from the value obtained in the local approximation for an infinitely long blob. For auroral ionosphere parameters, the reduction in the growth rate for medium scale irregularities (1-10 km) can be one to two orders of magnitude for the typical observed values of blob sizes (approx. a few hundred km). Thus, it appears that the current convective instability is not a viable mechanism to generate scintillation causing irregularities, i.e., 1-10 km irregularities.

  15. Plasma dynamics in Saturn's middle-latitude ionosphere and implications for magnetosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Sakai, Shotaro; Watanabe, Shigeto

    2016-08-01

    A multifluid model is used to investigate how Saturn's magnetosphere affects ionosphere. The model includes a magnetospheric plasma temperature of 2 eV as a boundary condition. The main results are: (1) H+ ions are accelerated along magnetic field lines by ambipolar electric fields and centrifugal force, and have an upward velocity of about 10 km/s at 8000 km; (2) the ionospheric plasma temperature is 10,000 K at 5000 km, and is significantly affected by magnetospheric heat flow at high altitudes; (3) modeled electron densities agree with densities from occultation observations if the maximum neutral temperature at a latitude of 54˚ is about 900 K or if electrons are heated near an altitude of 2500 km; (4) electron heating rates from photoelectrons (≈100 K/s) can also give agreement with observed electron densities when the maximum neutral temperature is lower than 700 K (note that Cassini observations give 520 K); and (5) the ion temperature is high at altitudes above 4000 km and is almost the same as the electron temperature. The ionospheric height-integrated Pedersen conductivity, which affects the magnetospheric plasma velocity, varies with local time with values between 0.4 and 10 S. We suggest that the sub-corotating ion velocity in the inner magnetosphere depends on the local time, because the conductivity generated by dust-plasma interactions in the inner magnetosphere is almost comparable to the ionospheric conductivity. This indicates that magnetosphere-ionosphere coupling is highly important in the Saturn system.

  16. Spatial Distribution of Ionospheric Plasma and Field Structures in the High-Latitude F Region

    NASA Technical Reports Server (NTRS)

    Kivanc, O.; Heelis, R. A.

    1998-01-01

    Ion density and velocity measurements from the Dynamics Explorer 2 (DE 2) spacecraft are used to obtain the average magnetic local time versus invariant latitude distribution of irregularities in the high-latitude F region ionosphere. To study the small-scale structure and its relationship to background conditions in the ionosphere, we have formed a reduced database using 2-s (approx. = 16 km) segments of the ion density and velocity data. The background gradients associated with each 2-s segment and the spectral characteristics, such as power at 6 Hz (approx. = 1.3 km) and spectral index, are among the reduced parameters used in this study. The relationship between the observed plasma structure and its motion is complex and dependent on the externally applied fields as well as locally generated plasma structure. The evolution of plasma structures also depends critically on the conductivity of the underlying ionosphere. Observations indicate an enhancement of irregularity amplitudes in two spatially isolated regions in both the ion density and the velocity. Convective properties seem to play a more important role in winter hemisphere where smaller-scale structures are maintained outside the source regions. (Delta)V irregularity amplitudes are enhanced in the cusp and the polar cap during northward interplanetary magnetic field regardless of season. The power in (Delta)V is usually higher than that associated with local polarization electric fields, suggesting that the observed structure in (Delta)N/N is strongly influenced by (Delta)V structure applied to large density gradients.

  17. Observations of ionospheric convection from the Wallops SuperDARN radar at middle latitudes

    NASA Astrophysics Data System (ADS)

    Baker, J. B. H.; Greenwald, R. A.; Ruohoniemi, J. M.; Oksavik, K.; Gjerloev, J. W.; Paxton, L. J.; Hairston, M. R.

    2007-01-01

    During geomagnetic storms the ability of the Super Dual Auroral Radar Network (SuperDARN) to measure ionospheric convection becomes limited when the radars suffer from absorption and the auroral disturbance expands equatorward of the radar sites. To overcome these shortcomings, it was decided to construct a SuperDARN radar at middle latitudes on the grounds of the NASA Wallops Flight Facility. This paper presents the first comprehensive analysis of Doppler measurements from the Wallops radar, which commenced operations in May 2005. Wallops measurements are compared with the Goose Bay radar during the onset of a geomagnetic storm on 31 August 2005: Goose Bay measured the onset of geomagnetic activity at high latitude while Wallops monitored the expansion of convection to middle latitudes. Average convection patterns binned by the Kp geomagnetic index are also presented. During weak-moderate geomagnetic activity (Kp ≤ 3) the Wallops radar observes ionospheric irregularities between 50° and 60° magnetic latitude drifting westward across much of the nightside. When these measurements are incorporated into the calculation of an average SuperDARN convection pattern, the streamlines of polar cap outflow on the nightside become kinked in a manner reminiscent of the Harang discontinuity. This morphology arises quite naturally when the two-cell convection at high latitudes merges with the prevailing westward convection at middle latitudes. During increased geomagnetic activity (Kp ≥ 3), Wallops is able to measure the expansion of auroral electric fields to middle latitudes and the average SuperDARN cross-polar cap potential is increased by 25%.

  18. Martian Atmospheric and Ionospheric plasma Escape

    NASA Astrophysics Data System (ADS)

    Lundin, Rickard

    2016-04-01

    Solar forcing is responsible for the heating, ionization, photochemistry, and erosion processes in the upper atmosphere throughout the lifetime of the terrestrial planets. Of the four terrestrial planets, the Earth is the only one with a fully developed biosphere, while our kin Venus and Mars have evolved into arid inhabitable planets. As for Mars, there are ample evidences for an early Noachian, water rich period on Mars. The question is, what made Mars evolve so differently compared to the Earth? Various hydrosphere and atmospheric evolution scenarios for Mars have been forwarded based on surface morphology, chemical composition, simulations, semi-empiric (in-situ data) models, and the long-term evolution of the Sun. Progress has been made, but the case is still open regarding the changes that led to the present arid surface and tenuous atmosphere at Mars. This presentation addresses the long-term variability of the Sun, the solar forcing impact on the Martian atmosphere, and its interaction with the space environment - an electromagnetic wave and particle interaction with the upper atmosphere that has implications for its photochemistry, composition, and energization that governs thermal and non-thermal escape. Non-thermal escape implies an electromagnetic upward energization of planetary ions and molecules to velocities above escape velocity, a process governed by a combination of solar EUV radiation (ionization), and energy and momentum transfer by the solar wind. The ion escape issue dates back to the early Soviet and US-missions to Mars, but the first more accurate estimates of escape rates came with the Phobos-2 mission in 1989. Better-quality ion composition measurement results of atmospheric/ionospheric ion escape from Mars, obtained from ESA Mars Express (MEX) instruments, have improved our understanding of the ion escape mechanism. With the NASA MAVEN spacecraft orbiting Mars since Sept. 2014, dual in-situ measurement with plasma instruments are now

  19. Small-scale plasma, magnetic, and neutral density fluctuations in the nightside Venus ionosphere

    SciTech Connect

    Hoegy, W.R.; Brace, L.H.; Kasprazak, W.T. ); Russell, C.T. )

    1990-04-01

    Pioneer Venus orbiter measurements have shown that coherent small-scale waves exist in the electron density, the electron temperature, and the magnetic field in the lower ionosphere of Venus just downstream of the solar terminator (Brace et al., 1983). The waves become less regular and less coherent at larger solar zenith angles, and Brace et al. suggested that these structures may have evolved from the terminator waves as they are convected into the nightside ionosphere, driven by the day-to-night plasma pressure gradient. In this paper the authors describe the changes in wave characteristics with solar zenith angle and show that the neutral gas also has related wave characteristics, probably because of atmospheric gravity waves. The plasma pressure exceeds the magnetic pressure in the nightside ionosphere at these altitudes, and thus the magnetic field is carried along and controlled by the turbulent motion of the plasma, but the wavelike nature of the thermosphere may also be coupled to the plasma and magnetic structure. They show that there is a significant coherence between the ionosphere, thermosphere, and magnetic parameters at altitudes below about 185 km, a coherence which weakens in the antisolar region. The electron temperature and density are approximately 180{degree} out of phase and consistently exhibit the highest correlation of any pair of variables. Waves in the electron and neutral densities are moderately correlated on most orbits, but with a phase difference that varies within each orbit. The average electron temperature is higher when the average magnetic field is more horizontal; however, the correlation between temperature and dip angle does not extend to individual wave structures observed within a satellite pass, particularly in the antisolar region.

  20. Central Plasma Sheet Ion Properties as Inferred from Ionospheric Observations

    NASA Technical Reports Server (NTRS)

    Wing, Simon; Newell, Patrick T.

    1998-01-01

    A method of inferring central plasma sheet (CPS) temperature, density, and pressure from ionospheric observations is developed. The advantage of this method over in situ measurements is that the CPS can be studied in its entirely, rather than only in fragments. As a result, for the first time, comprehensive two-dimensional equatorial maps of CPS pressure, density, and temperature within the isotropic plasma sheet are produced. These particle properties are calculated from data taken by the Special Sensor for Precipitating Particles, version 4 (SSJ4) particle instruments onboard DMSP F8, F9, F10, and F11 satellites during the entire year of 1992. Ion spectra occurring in conjunction with electron acceleration events are specifically excluded. Because of the variability of magnetotail stretching, the mapping to the plasma sheet is done using a modified Tsyganenko [1989] magnetic field model (T89) adjusted to agree with the actual magnetotail stretch at observation time. The latter is inferred with a high degree of accuracy (correlation coefficient -0.9) from the latitude of the DMSP b2i boundary (equivalent to the ion isotropy boundary). The results show that temperature, pressure, and density all exhibit dawn-dusk asymmetries unresolved with previous measurements. The ion temperature peaks near the midnight meridian. This peak, which has been associated with bursty bulk flow events, widens in the Y direction with increased activity. The temperature is higher at dusk than at dawn, and this asymmetry increases with decreasing distance from the Earth. In contrast, the density is higher at dawn than at dusk, and there appears to be a density enhancement in the low-latitude boundary layer regions which increases with decreasing magnetic activity. In the near-Earth regions, the pressure is higher at dusk than at dawn, but this asymmetry weakens with increasing distance from the Earth and may even reverse so that at distances X less than approx. 10 to -12 R(sub E

  1. Mapping high-latitude plasma convection with coherent HF radars

    NASA Technical Reports Server (NTRS)

    Ruohoniemi, J. M.; Greenwald, R. A.; Baker, K. B.; Villain, J.-P.; Hanuise, C.

    1989-01-01

    Several methods developed for mapping high-latitude plasma convection with a high-latitude HF radar are described, which utilize coherent backscatter from electron density irregularities at F-region altitudes to observe convective plasma motion. Several examples of two-dimensional convection-velocity maps are presented, showing instances of L-shell-aligned flow in the dusk sector, the reversal of convection near magnetic midnight, and counterstreaming in the dayside cleft.

  2. Ionospheric plasma dynamics and instability caused by upward currents above thunderstorms

    NASA Astrophysics Data System (ADS)

    Kuo, C. L.; Lee, L. C.

    2015-04-01

    Thunderstorms are electric generators, which drive currents upwardly into the ionosphere. In this paper, we examine the effects of thunderstorm upward current on the ionosphere. We use a thunderstorm model to calculate the three-dimensional current flows in the atmosphere and to simulate the upward current above the thunderstorm with the tripole-charge structure. The upward current flows into the ionosphere, while the associated electric field causes the plasma E × B motion. The caused plasma motion redistributes the plasma density, leading to ionospheric density variations. In the nighttime ionosphere, the E × B motion may also cause the formation of plasma bubbles.

  3. Diffuse spreading of inhomogeneities in the ionospheric dusty plasma

    SciTech Connect

    Shalimov, S. L.; Kozlovsky, A.

    2015-08-15

    According to results of sounding of the lower ionosphere at altitudes of about 100 km, the duration of radio reflections from sufficiently dense ionized meteor trails, which characterizes their lifetime, can reach a few tens of seconds to several tens of minutes. This is much longer than the characteristic spreading time (on the order of fractions of a second to several seconds) typical in meteor radar measurements. The presence of dust in the lower ionosphere is shown to affect the ambipolar diffusion coefficient, which determines the spreading of plasma inhomogeneities. It is found that the diffusion coefficient depends substantially on the charge and size of dust grains, which allows one to explain the results of ionospheric sounding.

  4. Generation of a severe convective ionospheric storm under stable Rayleigh-Taylor conditions: triggering by meteors?

    NASA Astrophysics Data System (ADS)

    Kelley, M. C.; Ilma, R. R.

    2016-02-01

    Here we report on four events detected using the Jicamarca Radio Observatory (JRO) over an 18-year period, in which huge convective ionospheric storms (CISs) occur in a stable ionosphere. We argue that these rare events could be initiated by meteor-induced electric fields. The meteor-induced electric fields map to the bottomside of the F region, causing radar echoes and a localized CIS. If and when a localized disturbance reaches 500 km, we argue that it becomes two-dimensionally turbulent and cascades structure to both large and small scales. This leads to long-lasting structure and, almost certainly, to scintillations over a huge range of latitudes some ±15° wide and to 3 m irregularities, which backscatter the VHF radar waves. These structures located at high altitudes are supported by vortices shed by the upwelling bubble in a vortex street.

  5. Application of nonlinear methods to the study of ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Chernyshov, A. A.; Mogilevsky, M. M.; Kozelov, B. V.

    2015-01-01

    Most of the processes taking place in the auroral region of Earth's ionosphere are reflected in a variety of dynamic forms of the aurora borealis. In order to study these processes it is necessary to consider temporary and spatial variations of the characteristics of ionospheric plasma. Most traditional methods of classical physics are applicable mainly for stationary or quasi-stationary phenomena, but dynamic regimes, transients, fluctuations, selfsimilar scaling could be considered using the methods of nonlinear dynamics. Special interest is the development of the methods for describing the spatial structure and the temporal dynamics of auroral ionosphere based on the ideas of percolation theory and fractal geometry. The fractal characteristics (the Hausdorff fractal dimension and the index of connectivity) of Hall and Pedersen conductivities are used to the description of fractal patterns in the ionosphere. To obtain the self-consistent estimates of the parameters the Hausdorff fractal dimension and the index of connectivity in the auroral zone, an additional relation describing universal behavior of the fractal geometry of percolation at the critical threshold is applied. Also, it is shown that Tsallis statistics can be used to study auroral ionosphere

  6. The effects of interplanetary magnetic field orientation on dayside high-latitude ionospheric convection

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.

    1984-01-01

    The Atmosphere Explorer C data base of Northern Hemisphere ionospheric convection signatures at high latitudes is examined during times when the interplanetary magnetic field orientation is relatively stable. It is found that when the interplanetary magnetic field (IMF) has its expected garden hose orientation, the center of a region where the ion flow rotates from sunward to antisunward is displaced from local noon toward dawn irrespective of the sign of By. Poleward of this rotation region, called the cleft, the ion convection is directed toward dawn or dusk depending on whether By is positive or negative, respectively. The observed flow geometry can be explained in terms of a magnetosphere solar wind interaction in which merging is favored in either the prenoon Northern Hemisphere or the prenoon Southern Hemisphere when the IMF has a normal sector structure that is toward or away, respectively.

  7. Multi-satellite Estimation of the Large-scale Current System and Convection Pattern in the Polar Ionosphere

    NASA Astrophysics Data System (ADS)

    Vennerstrom, S.; Moretto, T.; Baker, K.; Olsen, N.; Luehr, H.

    2006-12-01

    Simultaneous high-precision magnetic field measurements from three satellites in low Earth orbit allow new approaches in studying the current systems in the polar ionosphere. The traditional method to infer field- aligned currents (FAC) from the along-track derivative of the magnetic measurements at a single satellite may be extended to a more comprehensive treatment, where the full current system, including both FACs and horizontal ionospheric Hall and Pedersen currents, is determined in a fit to the observed magnetic field. Here we investigate the potential of such methods in a study of the relationship between the field-aligned and ionospheric currents and ionospheric electric fields in the polar regions. We compare the magnetic perturbations measured by the Oersted, SAC-C and CHAMP satellites with SUPERDARN measurements of the convection electric field on event bases. We select events of moderate activity where Oersted and CHAMP cross the polar region simultaneously and with large angles between the two orbit planes. From the Oersted and CHAMP data we estimate the large scale FAC pattern. Based on this and on various models for ionospheric conductance, we estimate the ionospheric electric fields and horizontal currents, which then can be compared to the SUPERDARN and magnetic satellite measurements. We hereby test the validity of current models of the relationship between the electric fields and currents, in particular the ability of statistical models of ionospheric conductance to reproduce the observed magnetic disturbance and convection patterns. The new method is developed in preparation for the coming ESA mission Swarm.

  8. The response of ionospheric convection in the polar cap to substorm activity

    NASA Technical Reports Server (NTRS)

    Lester, M.; Lockwood, M.; Yeoman, T. K.; Cowley, S. W. H.; Luehr, H.; Bunting, R.; Farrugia, C. J.

    1995-01-01

    We report multi-instrument observations during an isolated substorm on 17 October 1989. The European Incoherent Scatter (EISCAT) radar operated in the SP-UK-POLI mode measuring ionospheric convection at latitudes 71 deg Lambda - 78 deg Lambda. Sub-Auroral Magnetometer Network (SAMNET) and the EISCAT Magnetometer Cross provide information on the timing of substorm expansion phase onset and subsequent intensifications, as well as the location of the field aligned and ionospheric currents associated with the substorm current wedge. Interplanetary Monitoring Platform-8 (IMP-8) magnetic field data are also included. Evidence of a substorm growth phase is provided by the equatorward motion of a flow reversal boundary across the EISCAT radar field of view at 2130 MLT, following a southward turning of the interplanetary magnetic field (IMF). We infer that the polar cap expanded as a result of the addition of open magnetic flux in the tail lobes during this interval. The flow reversal boundary, which is a lower limit to the polar cap boundary, reached an invariant latitude equatorward of 71 deg Lambda by the time of the expansion phase onset. We conclude that the substorm onset region in the ionosphere, defined by the westward electrojet, mapped to a part of the tail radially earthward of the boundary between open and closed magnetic flux, the distant neutral line. Thus the substorm was not initiated at the distant neutral line, although there is evidence that it remained active during the expansion phase.

  9. New method for tracking the movement of ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Benton, C. J.; Mitchell, C. N.

    2012-09-01

    A method to track the flow of plasma in the Earth's ionosphere is presented. This takes maps of total electron content (TEC) at various times, and by comparing them derives a map of bulk velocities. The method is a modification of the Horn-Schunck scheme used in computer vision, whereby the aperture problem (caused by the scalar input field not containing enough information to uniquely constrain the vector output field) is overcome by making pragmatic assumptions about the divergence and rotation of the flow. The continuity equation linking plasma velocity and density is given source terms constrained by models of plasma generation and recombination. This can be used to mitigate solar terminator effects, where the close proximity of daytime plasma generation and nighttime recombination causes the impression of plasma flow. The method successfully reconstructs the behavior of test data. It also gives plausible results with real electron density maps from the 2003 Halloween Storms.

  10. The interplanetary electric field, cleft currents and plasma convection in the polar caps

    NASA Technical Reports Server (NTRS)

    Banks, P. M.; Clauer, C. R.; Araki, T.; St. Maurice, J. P.; Foster, J. C.

    1984-01-01

    The relationship between the pattern of plasma convection in the polar cleft and the dynamics of the interplanetary electric field (IEF) is examined theoretically. It is shown that owing to the geometrical properties of the magnetosphere, the East-West component of the IEF will drive field-aligned currents which connect to the ionosphere at points lying on either side of noon, while currents associated with the North-South component of the IEF will connect the two polar caps as sheet currents, also centered at 12 MLT. In order to describe the consequences of the Interplanetary Magnetic Field (IMF) effects upon high-latitude electric fields and convection patterns, a series of numerical simulations was carried out. The simulations were based on a solution to the steady-state equation of current continuity in a height-integrated ionospheric current. The simulations demonstrate that a simple hydrodynamical model can account for the narrow 'throats' of strong dayside antisunward convection observed during periods of southward interplanetary IMF drift, as well as the sunward convection observed during periods of strongly northward IMF drift.

  11. Radio pumping of ionospheric plasma with orbital angular momentum.

    PubMed

    Leyser, T B; Norin, L; McCarrick, M; Pedersen, T R; Gustavsson, B

    2009-02-13

    Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE. PMID:19257597

  12. Radio Pumping of Ionospheric Plasma with Orbital Angular Momentum

    SciTech Connect

    Leyser, T. B.; Norin, L.; McCarrick, M.; Pedersen, T. R.; Gustavsson, B.

    2009-02-13

    Experimental results are presented of pumping ionospheric plasma with a radio wave carrying orbital angular momentum (OAM), using the High Frequency Active Auroral Research Program (HAARP) facility in Alaska. Optical emissions from the pumped plasma turbulence exhibit the characteristic ring-shaped morphology when the pump beam carries OAM. Features of stimulated electromagnetic emissions (SEE) that are attributed to cascading Langmuir turbulence are well developed for a regular beam but are significantly weaker for a ring-shaped OAM beam in which case upper hybrid turbulence dominates the SEE.

  13. Numerical simulation of the interaction between two high-energy plasma bunches in the ionosphere

    NASA Astrophysics Data System (ADS)

    Motorin, A. A.; Stupitsky, E. L.; Kholodov, A. S.

    2016-07-01

    The 3D MHD algorithm developed by us has been adapted to modeling the interaction between two plasma bunches in the ionosphere, mainly in order to sufficiently correctly describe the physics of the interaction between two plasma regions with regard to the ionospheric inhomogeneity and the geomagnetic field action. Modeling has been performed for several versions of location of the plasma region centers.

  14. Final Progress Report for Ionospheric Dusty Plasma In the Laboratory [Smokey Plasma

    SciTech Connect

    Robertson, Scott

    2010-09-28

    Ionospheric Dusty Plasma in the Laboratory” is a research project with the purpose of finding and reproducing the characteristics of plasma in the polar mesosphere that is unusually cold (down to 140 K) and contains nanometer-sized dust particles. This final progress report summarizes results from four years of effort that include a final year with a no-cost extension.

  15. Artificial plasma jet in the ionosphere

    NASA Astrophysics Data System (ADS)

    Haerendel, G.; Sagdeev, R. Z.

    The dynamics of an artificially injected plasma beam in the near-earth space are analyzed in terms of the beam structure, its propagation across the magnetic field, and the resulting wave phenomena (Porcupine Project, flight 4, March 31, 1979). Out of the four ejectable canisters attached to the main payload, two were instrumented by the U.S., one by the USSR (the Xenon plasma beam experiment), and one by West Germany (carrying a barium ion jet experiment). The propagation of the plasma seems to occur in three stages, with high-frequency broad-band oscillations mainly localized in the 'core' of the jet, while low-frequency oscillations were spatially separated from it. The generation region of LF oscillations was found to be much wider than the jet core. As a result of the interaction between the plasma beam and the ambient medium a heating of electrons, up to energies of about 20 eV, associated with LF noise was observed. The behavior of high-energy ions and the observed HF wave phenomena need further analysis.

  16. Ionospheric plasma drift and structure studies at high and mid-latitudes. Volume 1. Final report, October 1990-October 1993

    SciTech Connect

    Reinisch, B.W.; Scali, J.L.; Dozois, C.; Crowley, G.

    1993-12-01

    Ground-based observations of the high latitude ionosphere with Digisonde sounders at Quaanaaq, Sondrestrom, Goose Bay, Argentina and Millstone Hill provide a description of the patch structure and the convection pattern in the polar cap. Correlation analysis of observed F-region plasma drifts with the orientation of the interplanetary magnetic field (measured by IMP8) lead to a new technique of deducing the signs of Bz and By from the measured drifts. Real time calculation of the plasma drift was successfully introduced at one of the Digisonde stations (Sondrestrom) providing the possibility of determining the IMF components in real time. Analysis of mid-latitude trough observation shows large westward velocities in the trough region. Digisonde data from Quaanaaq and DMSP F8 and F9 satellite data showed the development of the ionospheric polar hole.

  17. Study plasma interactions in the auroral ionosphere

    NASA Technical Reports Server (NTRS)

    Anderson, H. R.; Wolf, R. A.

    1983-01-01

    Analyzed data from rocket flight, 29.007UE is presented. In a discrete electron arc the measured upward moving electrons are well accounted for by secondaries produced in collisional scattering of the measured downcoming electrons. No collective mechanisms need to invoke. The low energy downcoming electrons are accounted for by thermal plasma accelerated through a potential drop of a few kV that specularly reflects upward-moving lower energy electrons. No low altitude collective effects need to invoke in the arc. Simultaneous measurements of electric field by double probes on 29.007 and the Chatanika Radar allow one to infer that there are upward drifting ions above the discrete electron arc, and there is a westward neutral wind in the discrete arc. Two rocket payloads were built to investigate plasma effects in the pulsating aurora.

  18. Effects of convection electric field on upwelling and escape of ionospheric O(+)

    NASA Technical Reports Server (NTRS)

    Cladis, J. B.; Chiu, Yam T.; Peterson, William K.

    1992-01-01

    A Monte Carlo code is used to explore the full effects of the convection electric field on distributions of upflowing O(+) ions from the cusp/cleft ionosphere. Trajectories of individual ions/neutrals are computed as they undergo multiple charge-exchange collisions. In the ion state, the trajectories are computed in realistic models of the magnetic field and the convection, corotation, and ambipolar electric fields. The effects of ion-ion collisions are included, and the trajectories are computed with and without simultaneous stochastic heating perpendicular to the magnetic field by a realistic model of broadband, low frequency waves. In the neutral state, ballistic trajectories in the gravitational field are computed. The initial conditions of the ions, in addition to ambipolar electric field and the number densities and temperatures of O(+), H(+), and electrons as a function of height in the cusp/cleft region were obtained from the results of Gombosi and Killeen (1987), who used a hydrodynamic code to simulate the time-dependent frictional-heating effects in a magnetic tube during its motion though the convection throat. The distribution of the ion fluxes as a function of height are constructed from the case histories.

  19. Plasma density observations from the Dynamic Ionosphere Cubesat Experiment (DICE)

    NASA Astrophysics Data System (ADS)

    Barjatya, A.; Swenson, C.; Fish, C. S.; Crowley, G.; Pilinski, M.; Azeem, S. I.; Neilsen, T. L.

    2012-12-01

    The Dynamic Ionosphere Cubesat Experiment (DICE) was launched into an eccentric low Earth orbit on October 28, 2011 on a NASA rocket from Vandenburg Air Force Base. DICE consists of two identical 1.5U CubeSats with a mission objective to study and characterize geomagnetic Storm Enhanced Density (SED) bulge and plume by multipoint measurements. Each identical spacecraft carries two Langmuir probes to measure in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a magnetometer to measure in-situ DC and AC magnetic fields. This work presents Langmuir probe data from both the CubeSats as they follow each other. The two Langmuir probes are deployed 180 degrees apart on 10cm long scissor booms from the top and bottom of the CubeSats. The probes are primarily operated in the ion saturation region as fixed bias probes to give relative plasma densities, but periodically swept (every 100 seconds) to give absolute plasma density and temperature. The derived densities will be compared to International Reference Ionosphere as well as other models.; Comparison of relative plasma density derived from two fixed bias Langmuir probes (DCP+ and DCP-) on DICE with IRI model.

  20. Small-scale plasma irregularities in the nightside Venus ionosphere

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Curtis, S. A.; Brace, L. H.

    1991-01-01

    The individual volt-ampere curves from the Pioneer Venus Orbiter electron temperature probe showed evidence for small-scale density irregularities, or short-period plasma waves, in regions of the nightside ionosphere where the Orbiter electric field detector observed waves in its 100-Hz channel. A survey of the nightside volt-ampere curves has revealed several hundred examples of such irregularities. The I-V structures correspond to plasma density structure with spatial scale sizes in the range of about 100-2000 m, or alternatively they could be viewed as waves having frequencies extending toward 100 Hz. They are often seen as isolated events, with spatial extent along the orbit frequently less than 80 km. The density irregularities or waves occur in or near prominent gradients in the ambient plasma concentrations both at low altitudes where molecular ions are dominant and at higher altitudes in regions of reduced plasma density where O(+) is the major ion. Electric field 100-Hz bursts occur simultaneously, with the majority of the structured I-V curves providing demonstrative evidence that at least some of the E field signals are produced within the ionosphere.

  1. Application of spherical cap harmonic analysis to plasma convection mapping at high latitudes

    NASA Astrophysics Data System (ADS)

    Fiori, Robyn A. D.

    The primary goal of this work is to develop, validate, and apply a new technique for mapping the high-latitude ionospheric plasma flow (convection pattern) from velocity measurements routinely performed by the Super Dual Auroral Radar (SuperDARN) network of high frequency (HF) radars. The currently employed FIT technique relies heavily on assumptions that are not always justifiable. A spherical cap harmonic analysis (SCHA) technique, traditionally used in handling geomagnetic field data, is introduced for mapping the high-latitude ionospheric convection pattern based on SuperDARN velocity measurements. The SCHA technique does not require contributions from a statistical model which is dependent on the magnitude and orientation of the interplanetary magnetic field (IMF), and does not confine the high-latitude flows to a specific region based on magnetic latitude. Several steps are taken to validate the SCHA convection mapping technique. First, it is demonstrated that the SCHA technique can reproduce an arbitrary pattern based on simulated data modified by a random noise component. SCHA maps of the global scale plasma flow pattern for various IMF conditions are next shown to be consistent with expectations for patterns reported in the literature. SCHA maps are compared to ion drifts measured by the Defense Meteorological Satellite Program (DMSP) satellites and with convection vectors inferred by merging SuperDARN measurements at beam crossings. The SCHA technique is shown to perform comparably to the FIT technique over regions of good data coverage. The SCHA technique provides a better representation of the ionospheric convection pattern for regions with limited data coverage and over regions of highly variable flow, particularly near the equatorward edge of the mapping region. SCHA analysis of SuperDARN data to create convection maps is expanded to include magnetometer measurements of the perturbation magnetic field. Plasma flow is determined from magnetometer data

  2. Investigation of a rare event where the polar ionospheric reverse convection potential does not saturate during a period of extreme northward IMF solar wind driving

    NASA Astrophysics Data System (ADS)

    Clauer, C. Robert; Xu, Zhonghua; Maimaiti, M.; Ruohoneimi, J. Michael; Scales, Wayne; Hartinger, Michael D.; Nicolls, Michael J.; Kaeppler, Stephen; Wilder, Frederick D.; Lopez, Ramon E.

    2016-06-01

    A variety of statistical studies have shown that the ionospheric polar potential produced by solar wind-magnetosphere-ionosphere coupling is linear for weak to moderate solar wind driving but becomes nonlinear during periods of very strong driving. It has been shown that this applies to the two-cell convection potential that develops during southward interplanetary magnetic field (IMF) and also to the reverse convection cells that develop during northward IMF. This has been described as polar potential saturation, and it appears to begin when the driving solar wind electric field becomes greater than 3 mV/m. Utilizing measurements from the Resolute Incoherent Scatter Radar (RISR-N), we examine ionospheric data near local noon within the reverse convection cells that developed during a period of very strong northward interplanetary magnetic field (IMF) on 12 September 2014. During this period we measure the electric field within the throat of the reverse convection cells to be near 150 mV/m at a time when the IMF is nearly 28 nT northward. This is far in excess of the 30-40 mV/m expected for polar potential saturation of the reverse convection cells. In fact, the development of the electric field responds linearly to the IMF Bz component throughout this period of extreme driving. The conditions in the solar wind show the solar wind velocity near 600 km/s, number density near 20 ions/cm3, and the Alfvén velocity about 75 km/s giving an Alfvén Mach number of 8. A search of several years of solar wind data shows that these values occur together 0.035% of the time. These conditions imply a high plasma β in the magnetosheath. We believe that condition of high β along with high mass density and a strong merging electric field in the magnetosheath are the significant parameters that produce the linear driving of the ionospheric electric field during this unusual period of extreme solar wind conditions. A discussion of current theories to account for cross-polar cap

  3. Connections between large-scale transport to the inner magnetosphere from the distant plasma sheet, region 2 coupling to the ionosphere, and substorm and storm dynamics (Invited)

    NASA Astrophysics Data System (ADS)

    Lyons, L. R.; Wang, C.; Zou, S.; Gkioulidou, M.; Nishimura, Y.; Shi, Y.; Kim, H.; Xing, X.; Nicolls, M. J.; Heinselman, C. J.

    2009-12-01

    Studies using a variety of ground-based and spacecraft observations, as well as the Rice Convection Model, have taught us much about the connection between plasma sheet transport and particle distributions within the inner plasma sheet. These studies have shown that plasma moves earthward (equatorward in the ionosphere) after enhancements in convection to reach the near-Earth plasma sheet, leading to the enhancements in plasma sheet pressure that are responsible for the growth phase of substorms and the partial ring current. The highest inner plasma sheet pressures likely occur in the subauroral polarization streams (SAPS) region of the evening-side convection cell, lying equatorward of the Harang reversal. Both the Harang reversal and SAPS are manifestations of the region 2 (R2) electrodynamical coupling, so that transport to the near-Earth plasma sheet is strongly influenced by the R2 magnetosphere-ionosphere coupling. Modeling results show that this transport, together with the concurrent R2 coupling, is also strongly dependent on the plasma distributions that enter the plasma sheet. However, the entering plasma distribution is expected to have substantial spatial and temporal structure, which should impart substantial spatial structure and time dependencies to the inner plasma sheet particle distributions. In addition, very recent analyses indicate that the temporal variations of the particle distribution entering the plasma sheet, and the ensuing transport of new particle distributions within the plasma sheet, is fundamental to understanding the substorm expansion phase. Taken together, the above results indicate that an important understanding of inner magnetosphere particle distributions and their dynamics, as well as of major geomagnetic disturbances, is likely to come from integrated studies of plasma sheet particle entry, particle transport, and electrodynamical coupling to the ionosphere.

  4. Electric Field Double Probe Measurements for Ionospheric Space Plasma Experiments

    NASA Technical Reports Server (NTRS)

    Pfaff, R.

    1999-01-01

    Double probes represent a well-proven technique for gathering high quality DC and AC electric field measurements in a variety of space plasma regimes including the magnetosphere, ionosphere, and mesosphere. Such experiments have been successfully flown on a variety of spacecraft including sounding rockets and satellites. Typical instrument designs involve a series of trades, depending on the science objectives, type of platform (e.g., spinning or 3-axis stabilized), expected plasma regime where the measurements will be made, available telemetry, budget, etc. In general, ionospheric DC electric field instruments that achieve accuracies of 0.1 mV/m or better, place spherical sensors at large distances (10m or more) from the spacecraft body in order to extend well beyond the spacecraft wake and sheath and to achieve large signal-to-noise ratios for DC and long wavelength measurements. Additional sets of sensors inboard of the primary, outermost sensors provide useful additional information, both for diagnostics of the plasma contact potentials, which particularly enhance the DC electric field measurements on non-spinning spacecraft, and for wavelength and phase velocity measurements that use the spaced receiver or "interferometer" technique. Accurate attitude knowledge enables B times V contributions to be subtracted from the measured potentials, and permits the measured components to be rotated into meaningful geophysical reference frames. We review the measurement technique for both DC and wave electric field measurements in the ionosphere discussing recent advances involving high resolution burst memories, multiple baseline double probes, new sensor surface materials, biasing techniques, and other considerations.

  5. Solar Wind Driven Plasma Fluxes from the Venus Ionosphere

    NASA Astrophysics Data System (ADS)

    Perez De Tejada, H. A.; Lundin, R. N.; Zhang, T.; Sauvaud, J. A.; Reyes-Ruiz, M.

    2012-12-01

    SOLAR WIND DRIVEN PLASMA FLUXES FROM THE VENUS IONOSPHERE H. Pérez-de-Tejada (1), R. Lundin (2), H. Durand-Manterola (1), S. Barabash (2), T. L. Zhang (3), J. A., Sauvaud (4), and M. Reyes-Ruiz (5) 1 - Institute of Geophysics, UNAM, México, D. F. 2 - Swedish Institute of Space Physics, Kiruna, Sweden 3 - Space Research Institute, Graz, Austria 4 - CESR, Toulouse, France 5 - Institute of Astronomy, UNAM, Ensenada, México Measurements conducted with the ASPERA-4 instrument and the magnetometer of the Venus Express spacecraft show that the kinetic pressure of planetary O+ ion fluxes measured in the Venus wake can be significantly larger than the local magnetic pressure and, as a result, those ions are not being driven by magnetic forces but by the kinetic energy of the solar wind. Beams of planetary O+ ions with those properties have been detected in several orbits of the Venus Express through the wake as the spacecraft traverses by the noon-midnight plane along its near polar trajectory. The momentum flux of the O+ ions leads to superalfvenic flow conditions. It is suggested that such O+ ion beams are produced in the vicinity of the magnetic polar regions of the Venus ionosphere where the solar wind erodes the local plasma leading to plasma channels that extend downstream from those regions.

  6. Transverse ion heating in multicomponent plasmas. [in ionosphere

    NASA Technical Reports Server (NTRS)

    Ashour-Abdalla, M.; Okuda, H.; Kim, S. Y.

    1987-01-01

    A new mechanism is proposed for plasma modes which can occur only in a multicomponent plasma and not in pure electron-ion plasma. The addition of ions creates a new instability near the ion-ion hybrid mode whose frequency is adequate for the wave to interact with oxygen ions. To study heating of ions (such as ionospheric oxygen ions) in presence of auroral electrons, several numerical simulations were carried out using a one-dimensional electrostatic code in a magnetic field. It was found that in the presence of electrons drifting along auroral field lines into the ionosphere, the ion-ion hybrid mode can be driven unstable when the electron drift speed is too small to excite the lower hybrid instability. Since the ion-ion mode has a smaller frequency than that of the lower hybrid waves, it can couple to the heavy ions, resulting in a substantial heating of heavy ions; on the other hand, because of their frequencies, the lower hybrid waves can accelerate only light ion species.

  7. Measuring ionospheric electron density using the plasma frequency probe

    SciTech Connect

    Jensen, M.D.; Baker, K.D. )

    1992-02-01

    During the past decade, the plasma frequency probe (PFP) has evolved into an accurate, proven method of measuring electron density in the ionosphere above about 90 km. The instrument uses an electrically short antenna mounted on a sounding rocket that is immersed in the plasma and notes the frequency where the antenna impedance is large and nonreactive. This frequency is closely related to the plasma frequency, which is a direct function of free electron concentration. The probe uses phase-locked loop technology to follow a changing electron density. Several sections of the plasma frequency probe circuitry are unique, especially the voltage-controlled oscillator that uses both an electronically tuned capacitor and inductor to give the wide tuning range needed for electron density measurements. The results from two recent sounding rocket flights (Thunderstorm II and CRIT II) under vastly different plasma conditions demonstrate the capabilities of the PFP and show the importance of in situ electron density measurements of understanding plasma processes. 9 refs.

  8. The ionospheric source of magnetospheric plasma is not a black box input for global models

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Liemohn, M. W.

    2016-06-01

    Including ionospheric outflow in global magnetohydrodynamic models of near-Earth outer space has become an important step toward understanding the role of this plasma source in the magnetosphere. Of the existing approaches, however, few tie the outflowing particle fluxes to magnetospheric conditions in a self-consistent manner. Doing so opens the magnetosphere-ionosphere system to nonlinear mass-energy feedback loops, profoundly changing the behavior of the magnetosphere-ionosphere system. Based on these new results, it is time for the community eschew treating ionospheric outflow as a simple black box source of magnetospheric plasma.

  9. Observations of large-scale plasma convection in the magnetosphere with respect to the geomagnetic activity level

    NASA Astrophysics Data System (ADS)

    Stepanov, A. E.; Khalipov, V. L.; Kotova, G. A.; Zabolotskii, M. S.; Golikov, I. A.

    2016-03-01

    The data of the ionospheric observations (the daily f plots) at the Yakutsk meridional chain of ionosondes (Yakutsk-Zhigansk-Batagai-Tixie Bay) with sharp decreases (breaks) in the critical frequency of the regular ionospheric F2 layer ( foF2) are considered. The data for 1968-1983 were analyzed, and the statistics of the foF2 break observations, which indicate that these breaks are mainly registered in equinoctial months and in afternoon and evening hours under moderately disturbed geomagnetic conditions, are presented. Calculations performed using the prognostic model of the high-latitude ionosphere indicate that the critical frequency break position coincides with the equatorial boundary of large-scale plasma convection in the dusk MLT sector.

  10. DyFK Simulation of Field-Aligned Ion Flows Observed by POLAR within Convecting Flux Over the Polar Ionosphere

    NASA Technical Reports Server (NTRS)

    Tu, J.-N.; Wu, X. Y.; Horwitz, J. L.; Stevenson, B. A.; Moore, T. E.; Coffey, V. N.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Ion (O+ and H+) parallel flows along antisunward convecting flux tubes across the polar ionosphere from day to night side are simulated by an extended Dynamic Fluid semiKinetic (DyFK) model. The collision dominated portion of the flux tubes is treated with a moment-based fluid model for altitudes from 120 ?1100 km, while the generalized semikinetic model is used for the topside through 3 RE region. The effects of cleft/auroral soft electron precipitation and wave-driven transverse ion heating are incorporated into the generalized semi-kinetic treatment of topside ionosphere. The simulated evolution of field-aligned ion flow parameters is compared with observations made by the Thermal Ion Dynamics Experiment (TIDE) on board the POLAR satellite near 5000 km altitude over the southern hemisphere polar ionosphere.

  11. Plasma Oscillations of charged Dust in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Musatenko, S. I.; Musatenko, Y. S.; Maksymenko, O. V.; Kurochka, E. V.; Choly, V. Y.; Lastochkin, A. V.

    2003-04-01

    The significant maximum near 28-30 Hz was found in Fourier spectrums of the ionosphere radionoise at l=2m on August 12, 1999. At night the frequency of the maximum was slowly changing from 20 to 50 Hz (50 Hz is Nyquist frequency). Additional experiments (some of them were taken during Perseids, Orionids, Leonids and Geminids meteor beams) lead us to the conclusion that the observed line is the line of ionospheric dusty plasma because its intensity becomes more stronger at the presence of the meteor shower. In the night time the charge of the dust grains is negative (‹10e) and under the quiet heliogeomagnetic conditions (SKp‹20) the line frequency is in the range of 10-50 Hz. During the magnetic storm the charges of the grains may grow substantially (~100e) and line frequency goes beyond the Nyquist frequency. In the daytime the charges on the grains are formed owing to the solar ultraviolet ionisation. The charge is positive and relatively high (~100-1000e) and the line frequency is out of detectable range (100-300 Hz). The only evident recharger is the solar terminator.

  12. Relationship between the observed and modeled modulation of the dayside ionospheric convection by the IMF B{sub y} component

    SciTech Connect

    Papitashvili, V.O.; Clauer, C.R.; Levitin, A.E.

    1995-05-01

    The Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) electrodynamic model (IZMEM) provides global patterns of polar ionospheric potential and is parameterized by the interplanetary magnetic field (IMF). Given IMF conditions measured by an upstream satellite, the model yields a good global approximation to the polar ionospheric convection patterns assuming the proper time delay. While the model assumes static patterns and is based upon statistical regression analysis of high-latitude magnetometer data, it can furnish an appropriate global context within which to examine time-varying phenomena. The authors use the IZMEM model to further develop their understanding of the coordinated analysis of Greenland radar, riometer, and magnetometer data on August 2, 1991, which is one of the geospace environment modeling program intervals. The event is characterized by geomagnetic pulsations observed near local magnetic noon, having a 25-min period and poleward phase propagation. A modulation of the intensity and orientation of the convection electric field is observed by the Sondrestrom incoherent scatter radar. Modeled global convection patterns show striking agreement with observations in the area covered by the radar field of view. The authors interpret observed phenomena as a direct ground-based evidence of the IMF B{sub y} component reconnection at the dayside magnetopause. 31 refs., 6 figs.

  13. High-resolution ionospheric observations and modeling over Belgium during the solar eclipse of 20 March 2015 including first results of ionospheric tilt and plasma drift measurements

    NASA Astrophysics Data System (ADS)

    Verhulst, Tobias G. W.; Sapundjiev, Danislav; Stankov, Stanimir M.

    2016-06-01

    The ionospheric behavior over Belgium during the partial solar eclipse of 20 March 2015 is analyzed based on high-resolution solar radio flux, vertical incidence sounding, and GPS TEC measurements. First results of ionosonde-based ionospheric plasma drift and tilt observations are presented and analyzed, including some traveling ionospheric disturbances caused by the eclipse. Also, collocated ionosonde and GPS measurements are used to reconstruct the time evolution of the vertical electron density distribution using the Royal Meteorological Institute (RMI) ionospheric specification system, called Local Ionospheric Electron Density profile Reconstruction (LIEDR).

  14. Artificial quasi-periodic plasma inhomogeneities in the lower ionosphere

    NASA Astrophysics Data System (ADS)

    Belikovich, V. V.; Benediktov, E. A.; Dmitriev, S. A.; Terina, G. I.

    Experimental results are presented on artificial quasi-periodic plasma inhomogeneities in a standing wave field of high-power shortwave radio transmission, at ionospheric altitudes of 75 to 115 km. A transmitter of an equivalent power of 20 MW periodically emitted for 10 to 20 sec an extraordinary component at frequencies of 5.5-5.75 MHz. Backward-scattered signals, at amplitudes of 40-70 dB below the specular channel level, were observed, and relaxation time fluctuation was noted to be within the range of from tenths of seconds to several seconds. The scattering height of the regular component of the sounding waves decreased as the sounding wave frequency approached the extraordinary component frequency of the disturbing radio emission, in accordance with the spatial synchronism condition (Belikovich et al., 1978). The feasibility of using the method for measurements at lower altitudes was shown.

  15. Applications of numerical codes to space plasma problems

    NASA Technical Reports Server (NTRS)

    Northrop, T. G.; Birmingham, T. J.; Jones, F. C.; Wu, C. S.

    1975-01-01

    Solar wind, earth's bowshock, and magnetospheric convection and substorms were investigated. Topics discussed include computational physics, multifluid codes, ionospheric irregularities, and modeling laser plasmas.

  16. Cassini observations of ionospheric plasma in Saturn's magnetotail lobes

    NASA Astrophysics Data System (ADS)

    Felici, M.; Arridge, C. S.; Coates, A. J.; Badman, S. V.; Dougherty, M. K.; Jackman, C. M.; Kurth, W. S.; Melin, H.; Mitchell, D. G.; Reisenfeld, D. B.; Sergis, N.

    2016-01-01

    Studies of Saturn's magnetosphere with the Cassini mission have established the importance of Enceladus as the dominant mass source for Saturn's magnetosphere. It is well known that the ionosphere is an important mass source at Earth during periods of intense geomagnetic activity, but lesser attention has been dedicated to study the ionospheric mass source at Saturn. In this paper we describe a case study of data from Saturn's magnetotail, when Cassini was located at ≃ 2200 h Saturn local time at 36 RS from Saturn. During several entries into the magnetotail lobe, tailward flowing cold electrons and a cold ion beam were observed directly adjacent to the plasma sheet and extending deeper into the lobe. The electrons and ions appear to be dispersed, dropping to lower energies with time. The composition of both the plasma sheet and lobe ions show very low fluxes (sometimes zero within measurement error) of water group ions. The magnetic field has a swept-forward configuration which is atypical for this region, and the total magnetic field strength is larger than expected at this distance from the planet. Ultraviolet auroral observations show a dawn brightening, and upstream heliospheric models suggest that the magnetosphere is being compressed by a region of high solar wind ram pressure. We interpret this event as the observation of ionospheric outflow in Saturn's magnetotail. We estimate a number flux between (2.95 ± 0.43) × 109 and (1.43 ± 0.21) × 1010 cm-2 s-1, 1 or about 2 orders of magnitude larger than suggested by steady state MHD models, with a mass source between 1.4 ×102 and 1.1 ×103 kg/s. After considering several configurations for the active atmospheric regions, we consider as most probable the main auroral oval, with associated mass source between 49.7 ±13.4 and 239.8 ±64.8 kg/s for an average auroral oval, and 10 ±4 and 49 ±23 kg/s for the specific auroral oval morphology found during this event. It is not clear how much of this mass is

  17. Phenomenology of structured plasma in the ionosphere. Technical report

    SciTech Connect

    Vickrey, J.F.; Cousins, M.D.; Tsunoda, R.T.; Walker, N.B.; Livingston, R.C.

    1983-03-01

    This report summarizes the results of the past year's efforts at SRI International to investigate experimentally and theoretically the processes that control the evolution of plasma structure in the natural and the nuclear environments. Important new results include a description of the anisotropy of large-scale and scintillation-producing plasma density irregularities at high latitudes and its convection domination, the refinement of a method to extract true irregularity drifts from spaced-receiver measurements, the first experimental observations of the formation of image striations, a model of image formation that shows the process (in agreement with observations) to be highly scale-size selective, and evidence that the previously puzzling seasonal patterns of equatorial spread-F occurrence are a result of the seasonal changes in the time of sunset in the conjugate E layers.

  18. Convective transport of plasma in the inner Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Liu, W. W.; Hill, T. W.

    1990-04-01

    The transport of plasma in the inner Jovian magnetosphere is investigated according to the corotating convection model of Hill et al. (1981), emphasizing mathematical aspects of the theory. A simplified but physically plausible boundary condition at the inner Io torus, representing a 5 percent density enhancement of S(+) ions in an 'active sector' that is fixed in Jovian (system III) longitude is employed. The convection electric field pattern resulting from this longitudinal mass anomaly alone is investigated, and then the theory to include the effects of Coriolis force and plasma acceleration is generalized. It is found that even a small (about 5 percent) longitudinal asymmetry of the inner torus produces a convection system capable of removing torus plasma from the magnetosphere on a time scale of order one month.

  19. The influence of IMF on the lower ionosphere plasma in high and middle latitudes

    NASA Technical Reports Server (NTRS)

    Bremer, J.

    1989-01-01

    As shown by ground-based absorption measurements, the lower ionospheric plasma is markedly controlled by the structure of the IMF. Whereas in high auroral and subauroral latitudes this effect is very pronounced, in midlatitudes its influence is less important. A comparison of these results with satellite data of the IMF and the solar wind speed confirms the important role of these components, not only during special events but also for the normal state of the ionospheric D region plasma.

  20. Toward an integrated view of ionospheric plasma instabilities: Altitudinal transitions and strong gradient case

    NASA Astrophysics Data System (ADS)

    Makarevich, Roman A.

    2016-04-01

    A general dispersion relation is derived that integrates the Farley-Buneman, gradient-drift, and current-convective plasma instabilities (FBI, GDI, and CCI) within the same formalism for an arbitrary altitude, wave propagation vector, and background density gradient. The limiting cases of the FBI/GDI in the E region for nearly field-aligned irregularities, GDI/CCI in the main F region at long wavelengths, and GDI at high altitudes are successfully recovered using analytic analysis. Numerical solutions are found for more general representative cases spanning the entire ionosphere. It is demonstrated that the results are consistent with those obtained using a general FBI/GDI/CCI theory developed previously at and near E region altitudes under most conditions. The most significant differences are obtained for strong gradients (scale lengths of 100 m) at high altitudes such as those that may occur during highly structured soft particle precipitation events. It is shown that the strong gradient case is dominated by inertial effects and, for some scales, surprisingly strong additional damping due to higher-order gradient terms. The growth rate behavior is examined with a particular focus on the range of wave propagations with positive growth (instability cone) and its transitions between altitudinal regions. It is shown that these transitions are largely controlled by the plasma density gradients even when FBI is operational.

  1. Investigation of plasma motion in the equatorial ionosphere

    NASA Astrophysics Data System (ADS)

    Oyekola, Oyedemi S.

    2016-07-01

    The structure of evening and nighttime F-region vertical drift component of is vital for understanding the physics of the development of the occurrence of equatorial irregularities. In addition, postsunset ionospheric height has also been attributed as one of the most important factors for the occurrence of equatorial irregularities. We report vertical plasma drift velocities derived from the base (h'F) and the peak height (hmF2) of F-layer using 1-year of data obtained at Ibadan (Geog Long 3.9oE) during International Geophysical Year (1957-58) period for geomagnetic quiet-time and high solar activity conditions. We compared our results with International Reference Ionosphere 2012 model (IRI-2012). The results of this investigation include: (a) overall local- time characteristics of vertical drift between 1800 LT and 0600 LT are in good agreement for equinoxes, December, and June; (b) annual vertical drift derived from time variation of h'F and hmF2 and the corresponding annual variation of h'F and hmF2 variation indicate low correlation (R = 0.30), while IRI-2012 model vertical drift and IRI-2012 model of hmF2 show fairly good correlation ( R = 0.67); (c) regression analysis between time variation of h'F and Scherliess / Fejer model demonstrate correlation coefficient of approximately 0.74 (equinox), 0.85 (December), 0.57 (June) and 0.74 (all-year), while that of time variation of hmF2 and IRI-2012 vertical velocities show 0.95 (equinox), 0.74 (December), 0.43 (June), and 0.74 (all-year); (d) plasma motion derived from the time rate of change of h'F and those of hmF2 are correlated at 0.94, 0.88, 0.63, and 0.90 for equinoxes, December, June, and all-year, respectively; (e) the evening prereversal vertical drifts enhancement rage between ~20 - 45 m/s, ~18 - 46 m/s, ~20 - 50 m/s for time variation of h'F, hmF2, and Scherliess / Fejer model, respectively; (f) the corresponding peak altitudes vary between 430 - 540 km (h'F), 560 - 740 km ( hmF2), and 570 - 620 km (IRI

  2. Ionospheric traveling convection vortices observed near the polar cleft - A triggered response to sudden changes in the solar wind

    NASA Technical Reports Server (NTRS)

    Friis-Christensen, E.; Vennerstrom, S.; Mchenry, M. A.; Clauer, C. R.

    1988-01-01

    Analysis of 20-second resolution magnetometer data from an array of temporary stations operated around Sondre Stromfjord, Greenland, during the summer of 1986 shows the signatures of localized ionospheric traveling convection vortices. An example of an isolated event of this kind observed near 08 local time is presented in detail. This event consists of a twin vortex pattern of convection consistent with the presence of two field-aligned current filaments separated by about 600 km in the east-west direction. This system of currents is observed to move westward (tailward) past the array of stations at about 4 km/sec. The event is associated with relative quiet time ionospheric convection and occurs during an interval of northward IMF. It is, however, associated with a large fluctuation in both the Z and Y components of the IMF and with a large sudden decrease in the solar wind number density. The propagation of the system is inconsistent with existing models of FTE current systems, but nevertheless appears to be related to a readjustment of the magnetopause boundary to a sudden change in the solar wind dynamic pressure and/or to a change in reconnection brought about by a sudden reorientation of the IMF.

  3. Model study of the effects of gravity wave dissipation on the thermosphere and ionosphere from deep convection worldwide

    NASA Astrophysics Data System (ADS)

    Vadas, Sharon; Liu, Hanli

    In this paper, we discuss the methods and results of a global modeling study for the effect of deep convection on the thermosphere and ionosphere through the dissipation of atmospheric gravity waves (GWs). The selected time periods are 15-27 June 2009, during the recent extreme solar minimum, and 15-27 June 2000, during the recent solar maximum. The convective plumes which overshot the tropopause are identified from IR images obtained by 5 satellites covering the Earth during each period. We model the excitation of GWs from these plumes, and ray trace them into the thermosphere using our ray trace model which has been upgraded to span the Earth. We then calculate the forcings/heatings/coolings which result when and where these GWs dissipate in the thermosphere. We input these forcings/heatings/coolings into the global TIME-GCM, and re-run the model. In this paper, we discuss these methods and models in detail. We then discuss how the thermosphere and ionosphere responded to the dissipation of these convectively-generated GWs worldwide. We show that the responses propagate westward due to wind filtering by tides in the lower thermosphere. We also show that the neutral temperature and wind perturbations are larger during extreme solar minimum than during solar maximum.

  4. Plasma heating, electric fields and plasma flow by electron beam ionospheric injection

    NASA Technical Reports Server (NTRS)

    Winckler, J. R.; Erickson, K. N.

    1990-01-01

    The electric fields and the floating potentials of a Plasma Diagnostics Payload (PDP) located near a powerful electron beam injected from a large sounding rocket into the auroral zone ionosphere have been studied. As the PDP drifted away from the beam laterally, it surveyed a region of hot plasma extending nearly to 60 m radius. Large polarization electric fields transverse to B were imbedded in this hot plasma, which displayed large ELF wave variations and also an average pattern which has led to a model of the plasma flow about the negative line potential of the beam resembling a hydrodynamic vortex in a uniform flow field. Most of the present results are derived from the ECHO 6 sounding rocket mission.

  5. Grid-Sphere Electrodes for Contact with Ionospheric Plasma

    NASA Technical Reports Server (NTRS)

    Stone, Nobie H.; Poe, Garrett D.

    2010-01-01

    Grid-sphere electrodes have been proposed for use on the positively biased end of electrodynamic space tethers. A grid-sphere electrode is fabricated by embedding a wire mesh in a thin film from which a spherical balloon is formed. The grid-sphere electrode would be deployed from compact stowage by inflating the balloon in space. The thin-film material used to inflate the balloon is formulated to vaporize when exposed to the space environment. This would leave the bare metallic spherical grid electrode attached to the tether, which would present a small cross-sectional area (essentially, the geometric wire shadow area only) to incident neutral atoms and molecules. Most of the neutral particles, which produce dynamic drag when they impact a surface, would pass unimpeded through the open grid spaces. However, partly as a result of buildup of a space charge inside the grid-sphere, and partially, the result of magnetic field effects, the electrode would act almost like a solid surface with respect to the flux of electrons. The net result would be that grid-sphere electrodes would introduce minimal aerodynamic drag, yet have effective electrical-contact surface areas large enough to collect multiampere currents from the ionospheric plasma that are needed for operation of electrodynamic tethers. The vaporizable-balloon concept could also be applied to the deployment of large radio antennas in outer space.

  6. The response of plasma density to breaking inertial gravity wave in the lower regions of ionosphere

    SciTech Connect

    Tang, Wenbo Mahalov, Alex

    2014-04-15

    We present a three-dimensional numerical study for the E and lower F region ionosphere coupled with the neutral atmosphere dynamics. This model is developed based on a previous ionospheric model that examines the transport patterns of plasma density given a prescribed neutral atmospheric flow. Inclusion of neutral dynamics in the model allows us to examine the charge-neutral interactions over the full evolution cycle of an inertial gravity wave when the background flow spins up from rest, saturates and eventually breaks. Using Lagrangian analyses, we show the mixing patterns of the ionospheric responses and the formation of ionospheric layers. The corresponding plasma density in this flow develops complex wave structures and small-scale patches during the gravity wave breaking event.

  7. Phenomena associated with complex (dusty) plasmas in the ionosphere during high-speed meteor showers

    SciTech Connect

    Kopnin, S. I.; Popel, S. I.; Yu, M. Y.

    2009-06-15

    Formation of dusty plasmas in the Earth's ionosphere at 80-120 km altitudes during high-speed meteor showers and its detectable manifestations are discussed. Emphasis is given to ground-based observations such as detection of low-frequency (<50 Hz) ionospheric radio noise, ground-based observations of infrasonic waves, and amplification of the intensity of green radiation at 557.7 nm from a layer at the 110-120 km altitude in the lower ionosphere. The physical processes responsible for these manifestations are considered.

  8. Modeling of the Convection and Interaction of Ring Current, Plasmaspheric and Plasma Sheet Plasmas in the Inner Magnetosphere

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Chen, Sheng-Hsien; Buzulukova, Natalia; Glocer, Alex

    2010-01-01

    Distinctive sources of ions reside in the plasmasphere, plasmasheet, and ring current regions at discrete energies constitute the major plasma populations in the inner/middle magnetosphere. They contribute to the electrodynamics of the ionosphere-magnetosphere system as important carriers of the global current system, in triggering; geomagnetic storm and substorms, as well as critical components of plasma instabilities such as reconnection and Kelvin-Helmholtz instability at the magnetospheric boundaries. Our preliminary analysis of in-situ measurements shoves the complexity of the plasmas pitch angle distributions at particularly the cold and warm plasmas, vary dramatically at different local times and radial distances from the Earth in response to changes in solar wind condition and Dst index. Using an MHD-ring current coupled code, we model the convection and interaction of cold, warm and energetic ions of plasmaspheric, plasmasheet, and ring current origins in the inner magnetosphere. We compare our simulation results with in-situ and remotely sensed measurements from recent instrumentation on Geotail, Cluster, THEMIS, and TWINS spacecraft.

  9. Turbulent convective flows in the solar photospheric plasma

    NASA Astrophysics Data System (ADS)

    Caroli, A.; Giannattasio, F.; Fanfoni, M.; Del Moro, D.; Consolini, G.; Berrilli, F.

    2015-10-01

    > The origin of the 22-year solar magnetic cycle lies below the photosphere where multiscale plasma motions, due to turbulent convection, produce magnetic fields. The most powerful intensity and velocity signals are associated with convection cells, called granules, with a scale of typically 1 Mm and a lifetime of a few minutes. Small-scale magnetic elements (SMEs), ubiquitous on the solar photosphere, are passively transported by associated plasma flows. This advection makes their traces very suitable for defining the convective regime of the photosphere. Therefore the solar photosphere offers an exceptional opportunity to investigate convective motions, associated with compressible, stratified, magnetic, rotating and large Rayleigh number stellar plasmas. The magnetograms used here come from a Hinode/SOT uninterrupted 25-hour sequence of spectropolarimetric images. The mean-square displacement of SMEs has been modelled with a power law with spectral index . We found for times up to and for times up to . An alternative way to investigate the advective-diffusive motion of SMEs is to look at the evolution of the two-dimensional probability distribution function (PDF) for the displacements. Although at very short time scales the PDFs are affected by pixel resolution, for times shorter than the PDFs seem to broaden symmetrically with time. In contrast, at longer times a multi-peaked feature of the PDFs emerges, which suggests the non-trivial nature of the diffusion-advection process of magnetic elements. A Voronoi distribution analysis shows that the observed small-scale distribution of SMEs involves the complex details of highly nonlinear small-scale interactions of turbulent convective flows detected in solar photospheric plasma.

  10. SuperDARN-derived plasma convection: Comparison with other data and application to field-aligned current measurements

    NASA Astrophysics Data System (ADS)

    Xu, Liang

    In this thesis, several aspects of the SuperDARN HF radar observations at high latitudes are investigated in cooperation with measurements performed by three other instruments, the Sondrestrom incoherent scatter radar, the ion drift meter onboard of the DMSP satellite and the CADI ionosonde. The first issue under investigation was consistency of plasma convection data provided by these instruments. First, routine measurements by the Goose Bay and Stokkseyri SuperDARN radar pair ("merge" velocity estimates) were compared with the Sondrestrom incoherent scatter radar data. Three different levels of assessment were used; by looking at the line-of-sight velocities, by comparing the SuperDARN vectors and corresponding Sondrestrom line-of-sight velocities and by comparing the end products of the instruments, the convection maps. All three comparisons showed overall reasonable agreement of the convection measurements though the data spread was significant and for some points a strong disagreement was obvious. Importantly, the convection map comparison showed a tendency for the SuperDARN velocities to be often less than the Sondrestrom drifts for strong flows (velocities > 1000 m/s) and larger for weak flows (velocities < 500 m/s). The second issue under investigation was the configuration of the ionospheric plasma convection and field-aligned currents (FACs) in the dayside ionosphere at small IMF B2 and By. By merging SuperDARN convection data for a number of events, it was found that convection tends to be compressed to the poleward edge of the polar cap with a noticeable decrease of the flow velociity inside the central polar cap for this condition. Also, for individual events, existence of three sheets of FACs was illustrated. FACs had similar appearance as region 1, region 2, and region 0 currents known from satellite magnetometer observations for the disturbed magnetosphere. Spatially, sheets of region 1 FACs were co-located with a line separating the plasma flow of

  11. On plasma convection in Saturn's magnetosphere

    NASA Astrophysics Data System (ADS)

    Livi, Roberto

    We use CAPS plasma data to derive particle characteristics within Saturn's inner magnetosphere. Our approach is to first develop a forward-modeling program to derive 1-dimensional (1D) isotropic plasma characteristics in Saturn's inner, equatorial magnetosphere using a novel correction for the spacecraft potential and penetrating background radiation. The advantage of this fitting routine is the simultaneous modeling of plasma data and systematic errors when operating on large data sets, which greatly reduces the computation time and accurately quantifies instrument noise. The data set consists of particle measurements from the Electron Spectrometer (ELS) and the Ion Mass Spectrometer (IMS), which are part of the Cassini Plasma Spectrometer (CAPS) instrument suite onboard the Cassini spacecraft. The data is limited to peak ion flux measurements within +/-10° magnetic latitude and 3-15 geocentric equatorial radial distance (RS). Systematic errors such as spacecraft charging and penetrating background radiation are parametrized individually in the modeling and are automatically addressed during the fitting procedure. The resulting values are in turn used as cross-calibration between IMS and ELS, where we show a significant improvement in magnetospheric electron densities and minor changes in the ion characteristics due to the error adjustments. Preliminary results show ion and electron densities in close agreement, consistent with charge neutrality throughout Saturn's inner magnetosphere and confirming the spacecraft potential to be a common influence on IMS and ELS. Comparison of derived plasma parameters with results from previous studies using CAPS data and the Radio And Plasma Wave Science (RPWS) investigation yields good agreement. Using the derived plasma characteristics we focus on the radial transport of hot electrons. We present evidence of loss-free adiabatic transport of equatorially mirroring electrons (100 eV - 10 keV) in Saturn's magnetosphere between

  12. Excitation of the lower oblique resonance by an artificial plasma jet in the ionosphere

    NASA Astrophysics Data System (ADS)

    Thiel, J.; Storey, L. R. O.; Bauer, O. H.; Jones, D.

    1984-04-01

    Aboard the Porcupine rockets, bursts of noise were detected in the electron whistler range during the operation of a xenon plasma gun on a package ejected from the main payload. These observations can be interpreted in terms of excitation of the lower oblique resonance by instabilities associated with the motion of the xenon ion beam through the ionospheric plasma.

  13. Low and Midlatitude Ionospheric Plasma Density Irregularities and Their Effects on Geomagnetic Field

    NASA Astrophysics Data System (ADS)

    Yokoyama, Tatsuhiro; Stolle, Claudia

    2016-10-01

    Earth's magnetic field results from various internal and external sources. The electric currents in the ionosphere are major external sources of the magnetic field in the daytime. High-resolution magnetometers onboard low-Earth-orbit satellites such as CHAMP and Swarm can detect small-scale currents in the nighttime ionosphere, where plasma density gradients often become unstable and form irregular density structures. The magnetic field variations caused by the ionospheric irregularities are comparable to that of the lithospheric contribution. Two phenomena in the nighttime ionosphere that contribute to the magnetic field variation are presented: equatorial plasma bubble (EPB) and medium-scale traveling ionospheric disturbance (MSTID). EPB is formed by the generalized Rayleigh-Taylor instability over the dip equator and grows nonlinearly to as high as 2000 km apex altitude. It is characterized by deep plasma density depletions along magnetic flux tubes, where the diamagnetic effect produced by a pressure-gradient-driven current enhances the main field intensity. MSTID is a few hundred kilometer-scale disturbance in the midlatitude ionosphere generated by the coupled electrodynamics between the ionospheric E and F regions. The field-aligned currents associated with EPBs and MSTIDs also have significant signatures in the magnetic field perpendicular to the main field direction. The empirical discovery of the variations in the magnetic field due to plasma irregularities has motivated the inclusion of electrodynamics in the physical modeling of these irregularities. Through an effective comparison between the model results and observations, the physical process involved has been largely understood. The prediction of magnetic signatures due to plasma irregularities has been advanced by modeling studies, and will be helpful in interpreting magnetic field observations from satellites.

  14. Whistler wave-induced ionospheric plasma turbulence: Source mechanisms and remote sensing

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Rooker, L. A.; Whitehurst, L. N.; Lee, M. C.; Ross, L. M.; Sulzer, M. P.; Gonzalez, S.; Tepley, C.; Aponte, N.; See, B. Z.; Hu, K. P.

    2013-10-01

    We report a series of experiments conducted at Arecibo Observatory in the past, aimed at the investigation of 40.75 kHz whistler wave interactions with ionospheric plasmas and the inner radiation belts at L=1.35. The whistler waves are launched from a Naval transmitter (code-named NAU) operating in Aguadilla, Puerto Rico at the frequency and power of 40.75 kHz and 100 kW, respectively. Arecibo radar, CADI, and optical instruments were used to monitor the background ionospheric conditions and detect the induced ionospheric plasma effects. Four-wave interaction processes produced by whistler waves in the ionosphere can excite lower hybrid waves, which can accelerate ionospheric electrons. Furthermore, whistler waves propagating into the magnetosphere can trigger precipitation of energetic electrons from the radiation belts. Radar and optical measurements can distinguish wave-wave and wave-particle interaction processes occurring at different altitudes. Electron acceleration by different mechanisms can be verified from the radar measurements of plasma lines. To facilitate the coupling of NAU-launched 40.75 kHz whistler waves into the ionosphere, we can rely on naturally occurring spread F irregularities to serve as ionospheric ducts. We can also use HF wave-created ducts/artificial waveguides, as demonstrated in our earlier Arecibo experiments and recent Gakona experiments at HAARP. The newly constructed Arecibo HF heater will be employed in our future experiments, which can extend the study of whistler wave interactions with the ionosphere and the magnetosphere/radiation belts as well as the whistler wave conjugate propagation between Arecibo and Puerto Madryn, Argentina.

  15. Plasma Cavern Structure in the Ionosphere F Layer at the Geomagnetic Equator according to the Kosmos 900 Satellite Data

    NASA Astrophysics Data System (ADS)

    Gdalevich, G. L.; Izhovkina, N. I.; Ozerov, V. D.

    2003-11-01

    The observational data on the plasma density and electron component temperature in the region of the geomagnetic equator in the ionosphere F layer are presented. The measurements have been conducted by scientific equipment onboard the Kosmos 900 satellite (on August 7, 1979). A plasma cavern was observed in this region. It is shown that the formation of the cavern may be related to the attenuation of the electrostatic plasma instability and plasma vortices in the upper ionosphere at the geomagnetic equator.

  16. High-latitude magnetospheric plasma convection and its dependence on solar wind parameters: Statistical analysis of Cluster EDI measurements

    NASA Astrophysics Data System (ADS)

    Förster, M.; Haaland, S. E.; Paschmann, G.; Quinn, J. M.; Torbert, R. B.; McIlwain, C. E.; Vaith, H.; Puhl-Quinn, P. A.; Kletzing, C. A.

    2006-12-01

    We have used vector measurements of the electron drift velocity by the Electron Drift Instrument (EDI) on Cluster between February 2001 and March 2006 to derive statistical maps of the high-latitude plasma convection. The EDI measurements, obtained at geocentric distances between ~4 and ~20RE over both hemispheres, are mapped into the polar ionosphere, and sorted according to the orientation of the interplanetary magnetic field (IMF), as measured at ACE and propagated to Earth, using best estimates of the orientation of the IMF variations. Only intervals of stable IMF are used, based on the magnitude of the so- called bias-vector constructed from 30-minute averages. Contour maps of the electric potential in the polar ionosphere are subsequently derived from the mapped and averaged ionospheric drift vectors. Comparison with published statistical results based on Super Dual Auroral Radar Network (SuperDARN) radar and low-altitude satellite measurements shows excellent agreement between the average convection patterns, particularly the lack of mirror-symmetry between the effects of positive and negative IMF B_y effects, the appearance of a duskward flow component for strongly southward IMF, and the general weakening of the flows and potentials for northerly IMF directions. This agreement lends credence to the validity of the assumption underlying the mapping of the EDI data, namely that magnetic field lines are equipotentials. For strongly northward IMF the mapped EDI data show the clear emergence of two counter-rotating lobe cells with a channel of sunward flow between them. The total potential drops across the polar caps obtained from the mapped EDI data are intermediate between the radar and the low-altitude satellite results. We have also sorted the data according to estimates of the reconnection electric field, solar wind dynamic pressure, and disturbance parameters such as DsT and ASYM-H. Finally, we have produced maps of the variances of the convection as a

  17. Remote detection of the maximum altitude of equatorial ionospheric plasma bubbles

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1981-01-01

    Nearly 200 post-sunset low-altitude passes of the Alouette 2 and ISIS 1 satellites near the dip equator are studied in order to find the maximum ionospheric plasma bubble altitudes, which are determined by calculating the apex altitude of the magnetic field line passing through the satellite when it is immersed in a bubble. The calculations are made only upon the observation of conjugate hemisphere ionospheric echoes, which result from ducted HF sounder signals that are guided along field-aligned irregularities within the plasma depletion. The maximum bubble altitudes corresponding to the three longitude sectors centered on zero deg, 75 deg W, and 105 deg E, are found to often exceed 1000 km, but seldom 3000 km. The electron density depletions within these field-aligned bubbles, as measured at the point of satellite encounter with the topside ionosphere, are generally less than a factor of two but may exceed a factor of ten.

  18. Ionosphere Plasma State Determination in Low Earth Orbit from International Space Station Plasma Monitor

    NASA Technical Reports Server (NTRS)

    Kramer, Leonard

    2014-01-01

    A plasma diagnostic package is deployed on the International Space Station (ISS). The system - a Floating Potential Measurement Unit (FPMU) - is used by NASA to monitor the electrical floating potential of the vehicle to assure astronaut safety during extravehicular activity. However, data from the unit also reflects the ionosphere state and seems to represent an unutilized scientific resource in the form of an archive of scientific plasma state data. The unit comprises a Floating Potential probe and two Langmuir probes. There is also an unused but active plasma impedance probe. The data, at one second cadence, are collected, typically for a two week period surrounding extravehicular activity events. Data is also collected any time a visiting vehicle docks with ISS and also when any large solar events occur. The telemetry system is unusual because the package is mounted on a television camera stanchion and its data is impressed on a video signal that is transmitted to the ground and streamed by internet to two off center laboratory locations. The data quality has in the past been challenged by weaknesses in the integrated ground station and distribution systems. These issues, since mid-2010, have been largely resolved and the ground stations have been upgraded. Downstream data reduction has been developed using physics based modeling of the electron and ion collecting character in the plasma. Recursive algorithms determine plasma density and temperature from the raw Langmuir probe current voltage sweeps and this is made available in real time for situational awareness. The purpose of this paper is to describe and record the algorithm for data reduction and to show that the Floating probe and Langmuir probes are capable of providing long term plasma state measurement in the ionosphere. Geophysical features such as the Appleton anomaly and high latitude modulation at the edge of the Auroral zones are regularly observed in the nearly circular, 51 deg inclined, 400 km

  19. Yosemite Conference on Ionospheric Plasma in the Magnetosphere: Sources, Mechanisms and Consequences, meeting report

    NASA Technical Reports Server (NTRS)

    Gallagher, D. L.; Burch, J. L.; Klumpar, D. M.; Moore, T. E.; Waite, J. H., Jr.

    1987-01-01

    The sixth biennial Yosemite topical conference and the first as a Chapman Conference was held on February 3 to 6, 1986. Due to the recent changes in our perception of the dynamics of the ionospheric/magnetospheric system, it was deemed timely to bring researchers together to discuss and contrast the relative importance of solar versus terrestrial sources of magnetospheric plasma. Although the solar wind was once thought to dominate the supply of plasma in the Earth's magnetosphere, it is now thought that the Earth's ionosphere is a significant contributor. Polar wind and other large volume outflows of plasma have been seen at relatively high altitudes over the polar cap and are now being correlated with outflows found in the magnetotail. The auroral ion fountain and cleft ion fountain are examples of ionospheric sources of plasma in the magnetosphere, observed by the Dynamics Explorer 1 (DE 1) spacecraft. The conference was organized into six sessions: four consisting of prepared oral presentations, one poster session, and one session for open forum discussion. The first three oral sessions dealt separately with the three major topics of the conference, i.e., the sources, mechanisms, and consequences of ionospheric plasma in the magnetosphere. A special session of invited oral presentations was held to discuss extraterrestrial ionospheric/magnetospheric plasma processes. The poster session was extended over two evenings during which presenters discussed their papers on a one-on-one basis. The last session of the conferences was reserved for open discussions of those topics or ideas considered most interesting or controversial.

  20. Ionospheric Plasma Response to M w 8.3 Chile Illapel Earthquake on September 16, 2015

    NASA Astrophysics Data System (ADS)

    Reddy, C. D.; Shrivastava, Mahesh N.; Seemala, Gopi K.; González, Gabriel; Baez, Juan Carlos

    2016-05-01

    The lithosphere and the atmosphere/ionosphere continuously exchange energy through various coupling mechanisms. In particular, the earth surface displacement caused by earthquakes, volcanoes and tsunamis can manifest as ionospheric plasma perturbations. We investigate the coseismic induced ionospheric total electron content (TEC) perturbations following the M w 8.3 Illapel thrust earthquake that occurred on September 16, 2015. The continuous global positioning system (GPS) data at 48 sites from Centro Sismológico Nacional and International GNSS Service GPS networks have been used in this study. The nearest GPS site recorded the ionospheric response 10 min after the occurrence of this earthquake. The maximum vertical coseismic induced TEC amplitude is ~1.4 TECU, and the perturbations are pronounced in the northern region of the epicenter and confined to less than ~1500 km radius. The average horizontal acoustic wave velocity has been determined as ~1260 m/s. We also observed acoustic resonance recorded by PRN 12 at 4.3 mHz corresponding to the first overtone of acoustic mode and lasting for about 30 min. In this study, we present characteristics of GPS derived ionospheric plasma perturbations following Illapel earthquake.

  1. Detection of the plasma density irregularities in the topside ionosphere with GPS measurements onboard Swarm satellites

    NASA Astrophysics Data System (ADS)

    Zakharenkova, Irina; Cherniak, Iurii

    2016-07-01

    We present new results on the detection of the topside ionospheric irregularities/plasma bubbles using GPS measurements from Precise Orbit Determination (POD) GPS antenna onboard Low Earth Orbit (LEO) satellites. For this purpose we analyze the GPS measurements onboard the ESA's constellation mission Swarm, consisted of three identical satellites with orbit altitude of 450-550 km. We demonstrate that LEO GPS can be an effective tool for monitoring the occurrence of the topside ionospheric irregularities and may essentially contribute to the multi-instrumental analysis of the ground-based and in situ data. In the present study we analyze the occurrence and global distribution of the equatorial ionospheric irregularities during post-sunset period. To support our observations and conclusions, we involve into our analysis in situ plasma density provided by Swarm constellation. Joint analysis of the Swarm GPS and in situ measurements allows us to estimate the occurrence rate of the topside ionospheric irregularities during 2014-2015. The obtained results demonstrate a high degree of similarities in the occurrence pattern of the seasonal and longitudinal distribution of the topside ionospheric irregularities derived on both types of the satellite observations. This work was partially funded by RFBR according to the research project No.16-05-01077 a.

  2. Ionospheric Plasma Drift Analysis Technique Based On Ray Tracing

    NASA Astrophysics Data System (ADS)

    Ari, Gizem; Toker, Cenk

    2016-07-01

    Ionospheric drift measurements provide important information about the variability in the ionosphere, which can be used to quantify ionospheric disturbances caused by natural phenomena such as solar, geomagnetic, gravitational and seismic activities. One of the prominent ways for drift measurement depends on instrumentation based measurements, e.g. using an ionosonde. The drift estimation of an ionosonde depends on measuring the Doppler shift on the received signal, where the main cause of Doppler shift is the change in the length of the propagation path of the signal between the transmitter and the receiver. Unfortunately, ionosondes are expensive devices and their installation and maintenance require special care. Furthermore, the ionosonde network over the world or even Europe is not dense enough to obtain a global or continental drift map. In order to overcome the difficulties related to an ionosonde, we propose a technique to perform ionospheric drift estimation based on ray tracing. First, a two dimensional TEC map is constructed by using the IONOLAB-MAP tool which spatially interpolates the VTEC estimates obtained from the EUREF CORS network. Next, a three dimensional electron density profile is generated by inputting the TEC estimates to the IRI-2015 model. Eventually, a close-to-real situation electron density profile is obtained in which ray tracing can be performed. These profiles can be constructed periodically with a period of as low as 30 seconds. By processing two consequent snapshots together and calculating the propagation paths, we estimate the drift measurements over any coordinate of concern. We test our technique by comparing the results to the drift measurements taken at the DPS ionosonde at Pruhonice, Czech Republic. This study is supported by TUBITAK 115E915 and Joint TUBITAK 114E092 and AS CR14/001 projects.

  3. Comparison of ionospheric plasma drifts obtained by different techniques

    NASA Astrophysics Data System (ADS)

    Kouba, Daniel; Arikan, Feza; Arikan, Orhan; Toker, Cenk; Mosna, Zbysek; Gok, Gokhan; Rejfek, Lubos; Ari, Gizem

    2016-07-01

    Ionospheric observatory in Pruhonice (Czech Republic, 50N, 14.9E) provides regular ionospheric sounding using Digisonde DPS-4D. The paper is focused on F-region vertical drift data. Vertical component of the drift velocity vector can be estimated by several methods. Digisonde DPS-4D allows sounding in drift mode with direct output represented by drift velocity vector. The Digisonde located in Pruhonice provides direct drift measurement routinely once per 15 minutes. However, also other different techniques can be found in the literature, for example the indirect estimation based on the temporal evolution of measured ionospheric characteristics is often used for calculation of the vertical drift component. The vertical velocity is thus estimated according to the change of characteristics scaled from the classical quarter-hour ionograms. In present paper direct drift measurement is compared with technique based on measuring of the virtual height at fixed frequency from the F-layer trace on ionogram, technique based on variation of h`F and hmF. This comparison shows possibility of using different methods for calculating vertical drift velocity and their relationship to the direct measurement used by Digisonde. This study is supported by the Joint TUBITAK 114E092 and AS CR 14/001 projects.

  4. Seasonal trends of nighttime plasma density enhancements in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Slominska, Ewa; Blecki, Jan; Lebreton, Jean-Pierre; Parrot, Michel; Slominski, Jan

    2014-08-01

    In situ registrations of electron density from the Langmuir probe on board Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions satellite are used to study spatial and temporal evolution of nighttime plasma density enhancements (NPDEs). The study introduces the normalized density difference index INDD in order to provide global estimates of the phenomenon. In the validation test, in situ data are compared with synthetic data set generated with the International Reference Ionosphere model. We find signatures of two most common examples of NPDEs, the Weddell Sea Anomaly (WSA) and midlatitude nighttime summer anomaly (MSNA) with proposed index, in the topside ionosphere. The study provides evidence that the occurrence of the WSA and MSNA is not limited to the local summer conditions. Analyzed annual trend of INDD and in particular spatial pattern obtained during equinoxes suggest that mechanisms governing the behavior of the equatorial ionosphere cannot be neglected in the explanation of the development of NPDEs.

  5. Magnetosphere-ionosphere coupling and scale breaking of a plasma cloud in the magnetosphere

    NASA Astrophysics Data System (ADS)

    Haerendel, Gerhard; Mende, Stephen B.

    2012-09-01

    The goal of this paper is to deliver a long-missing interpretation of a central issue of the NASA-MPE barium injection experiment performed in September 1971. It pertains to the interaction with the ionosphere. Observations of the cloud's motion revealed no obvious sign of such interaction. The barium vapor was released from a Scout rocket at an altitude of 31,000 km above South America during late evening hours and was observed for more than 4000 s. The barium plasma split into several field-parallel streaks which moved for a long time as if subject to constant acceleration as viewed from the inertial frame of the rocket at release. This means that no reflection of energy due to a mismatch of ionospheric conductivity and the characteristic impedance of an impinging Alfvén wave was observed. It is this finding that has never been properly interpreted. Furthermore, after a careful assessment of the barium cloud properties and environmental parameters, we find a theoretical coupling time to the ambient flow which turns out to be substantially longer than observed. Although this appears to indicate that some interaction with the ionosphere occurred, we can rule out multiple wave reflections during the observed acceleration phase. Discarding other possibilities, we interpret the observed motions as sign of perfect matching of the momentum and energy flux into the ionosphere with the rate of dissipation. This is achieved during the initial phase by scale breaking of the cloud into streaks with narrow widths which allow parallel potential drops along the Alfvén wings because of the waves' inertial nature and inside the lower ionosphere owing to the finite parallel resistivity, thereby greatly reducing the effective Pedersen conductivity. The significance of this finding goes beyond understanding the barium injection experiment. It sheds light on how magnetospheric plasma irregularities can share momentum and energy with the ionosphere in an optimized fashion.

  6. Plasma irregularities in the D-region ionosphere in association with sprite streamer initiation

    NASA Astrophysics Data System (ADS)

    Qin, Jianqi; Pasko, Victor P.; McHarg, Matthew G.; Stenbaek-Nielsen, Hans C.

    2014-05-01

    Sprites are spectacular optical emissions in the mesosphere induced by transient lightning electric fields above thunderstorms. Although the streamer nature of sprites has been generally accepted, how these filamentary plasmas are initiated remains a subject of active research. Here we present observational and modelling results showing solid evidence of pre-existing plasma irregularities in association with streamer initiation in the D-region ionosphere. The video observations show that before streamer initiation, kilometre-scale spatial structures descend rapidly with the overall diffuse emissions of the sprite halo, but slow down and stop to form the stationary glow in the vicinity of the streamer onset, from where streamers suddenly emerge. The modelling results reproduce the sub-millisecond halo dynamics and demonstrate that the descending halo structures are optical manifestations of the pre-existing plasma irregularities, which might have been produced by thunderstorm or meteor effects on the D-region ionosphere.

  7. Plasma irregularities in the D-region ionosphere in association with sprite streamer initiation.

    PubMed

    Qin, Jianqi; Pasko, Victor P; McHarg, Matthew G; Stenbaek-Nielsen, Hans C

    2014-01-01

    Sprites are spectacular optical emissions in the mesosphere induced by transient lightning electric fields above thunderstorms. Although the streamer nature of sprites has been generally accepted, how these filamentary plasmas are initiated remains a subject of active research. Here we present observational and modelling results showing solid evidence of pre-existing plasma irregularities in association with streamer initiation in the D-region ionosphere. The video observations show that before streamer initiation, kilometre-scale spatial structures descend rapidly with the overall diffuse emissions of the sprite halo, but slow down and stop to form the stationary glow in the vicinity of the streamer onset, from where streamers suddenly emerge. The modelling results reproduce the sub-millisecond halo dynamics and demonstrate that the descending halo structures are optical manifestations of the pre-existing plasma irregularities, which might have been produced by thunderstorm or meteor effects on the D-region ionosphere. PMID:24806314

  8. Plasma irregularities in the D-region ionosphere in association with sprite streamer initiation.

    PubMed

    Qin, Jianqi; Pasko, Victor P; McHarg, Matthew G; Stenbaek-Nielsen, Hans C

    2014-05-07

    Sprites are spectacular optical emissions in the mesosphere induced by transient lightning electric fields above thunderstorms. Although the streamer nature of sprites has been generally accepted, how these filamentary plasmas are initiated remains a subject of active research. Here we present observational and modelling results showing solid evidence of pre-existing plasma irregularities in association with streamer initiation in the D-region ionosphere. The video observations show that before streamer initiation, kilometre-scale spatial structures descend rapidly with the overall diffuse emissions of the sprite halo, but slow down and stop to form the stationary glow in the vicinity of the streamer onset, from where streamers suddenly emerge. The modelling results reproduce the sub-millisecond halo dynamics and demonstrate that the descending halo structures are optical manifestations of the pre-existing plasma irregularities, which might have been produced by thunderstorm or meteor effects on the D-region ionosphere.

  9. Application of the coded long-pulse technique to plasma line studies of the ionosphere

    NASA Technical Reports Server (NTRS)

    Djuth, Frank T.; Sulzer, Michael P.; Elder, John H.

    1994-01-01

    Recently, the coded long-pulse radar technique was tested at Arecibo Observatory, Puerto Rico using photoelectron-enhanced plasma lines in the daytime ionosphere. The technique immediately proved to be a powerful diagnostic tool for studying natural ionospheric phenomena. Our initial observations indicate that extremely accurate measurements of absolute electron density (0.01 to 0.03% error bars) can be achieved with an altitude resolution of 150 m and a temporal resolution of approx. 2 s. In addition, the technique provides information about electron density structure within a 150-m altitude cell and yields parameters from which the energy spectrum of suprathermal electrons (equal to or greater than 5 eV) can be deduced. Our earliest measurements are used to illustrate applications of the coded long-pulse technique to several aeronomic/ionsospheric areas of current interest. These include studies of neutral wave motions in the lower thermosphere, measurements of ion composition in the F(sub 1) region/upper ionosphere, and investigations of electron-gas thermal balance and photoelectron energy loss processes. The technique can be utilized to examine irregularity formation in the F region, probe electron acceleration processes in ionospheric modification experiments, verify the magnetic field dependence of Langmuir wave damping, and more generally test higher order corrections suggested for the Langmuir dispersion relation. It is anticipated that the latter tests will facilitate measurements of ionospheric currents.

  10. Description of the mean behaviour of ionospheric plasma temperatures

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter

    1987-01-01

    A status report on the empirical modeling of ionospheric electron and ion temperatures is given with special emphasis on the models used in the International Reference Ionosphere (IRI). Electron temperature models have now reached a state where reliable prediction of the mean altitudinal, latitudinal and diurnal variations is possible. These models are largely based on satellite measurements, but comparisons with incoherent scatter radar measurements have shown excellent agreement. Variations with season and magnetic and solar activity seem to be small and are not yet included consistently in these models. Similar to the electron temperature, the ion temperature shows the largest variations with altitude, latitude and local time. But due to the larger mass, these variations are smoother and more steady in the case of the ions and therefore easier to model. Nevertheless, very few ion temperature models exist. The IRI model takes advantage of the observed concurrence of the ion temperature with the neutral temperature at low altitudes and with the electron temperature at high altitudes.

  11. Linking Plasma Conditions in the Magnetosphere with Ionospheric Signatures

    NASA Technical Reports Server (NTRS)

    Rastaetter, Lutz; Kozyra, Janet; Kuznetsova, Maria M.; Berrios, David H.

    2012-01-01

    Modeling of the full magnetosphere, ring current and ionosphere system has become an indispensable tool in analyzing the series of events that occur during geomagnetic storms. The CCMC has a full model suite available for the magnetosphere, together with visualization tools that allow a user to perform a large variety of analyses. The January, 21, 2005 storm was a moderate-size storm that has been found to feature a large penetration electric field and unusually large polar caps (low-latitude precipitation patterns) that are otherwise found in super storms. Based on simulations runs at CCMC we can outline the likely causes of this behavior. Using visualization tools available to the online user we compare results from different magnetosphere models and present connections found between features in the magnetosphere and the ionosphere that are connected magnetically. The range of magnetic mappings found with different models can be compared with statistical models (Tsyganenko) and the model's fidelity can be verified with observations from low earth orbiting satellites such as DMSP and TIMED.

  12. Does a localized plasma disturbance in the ionosphere evolve to electrostatic equilibrium? Evidence to the contrary

    NASA Astrophysics Data System (ADS)

    Cosgrove, Russell B.

    2016-01-01

    Electrostatic equilibrium must be achieved through electromagnetic evolution. From an initial state with nonzero neutral wind localized along the geomagnetic field, and with all other plasma and electromagnetic perturbations initially zero, evolution progresses from plasma velocity to electric field to magnetic field, where the last step can launch an Alfvén wave that transmits the electromagnetic disturbance along geomagnetic field lines. Without the Alfvén wave the disturbance does not map along geomagnetic field lines, and there is no semblance of electrostatic equilibrium. This paradigm is essentially the traditional magnetosphere/ionosphere coupling paradigm, except addressed to smaller-scale, local ionospheric phenomena. However, Alfvén waves have not been thoroughly studied in the context of the partially ionized, collisional ionospheric plasma, and so the full effects predicted by this modeling paradigm are not known. In this work we adopt the two-fluid equations and investigate whether the ionosphere supports Alfvén-type waves that can transmit disturbances along geomagnetic field lines and perform a wave analysis of the "lumped circuit" parameters normally used to characterize the ionosphere under electrostatic equilibrium. We find that under the wave analysis (1) the Pedersen conductivity is severely modified and has a negative real part at short wavelengths; (2) the mapping distance for electric fields is significantly modified, and there is a nonnegligible wavelength along the geomagnetic field; and (3) the load admittance seen by a localized dynamo is strongly reactive, causing a phase offset between electric field and current, as compared with that when the load is electrostatic.

  13. Boundary location of Mars nightside ionospheric plasma in term of the electron density

    NASA Astrophysics Data System (ADS)

    Morooka, Michiko W.; Andersson, Laila; Ergun, Bob; Fowler, Christopher; Woodson, Adam; Weber, Tristan; Delory, Greg; Andrews, David; Edberg, Niklas; Eriksson, Anders; Michell, David; Connerney, Jack; Gruesbeck, Jacob; Halekas, Jasper

    2015-11-01

    Photo-ionized Mars atmosphere is forming an ionosphere and shielding the solar wind with creating barriers of bow shock. Inside the bow shock ionospheric plasma interact with solar wind plasma and result different boundaries. A question is how far the ionospheric plasma can stand off the solar wind.On the dayside, in-situ data set from Mars magnetosphere missions often observed the sharp gradient of the thermal plasma flux and ion composition change as well as the drop off of the magnetic fluctuation simultaneously as a outer boundary of the ionospheric plasma and an obstacle to the solar wind. Several models have constructed the shape of the boundary based on the statistical observations [e.g., Trotignon et al., 2006; Edberg et al., 2008].On the nightside, plasma instrument onboard Phobos 2 observed the particles and magnetic field characteristics similar to the dayside. However, the number of data is still too few to understand the general location of boundaries. We will present the characteristics of the nightside magnetospheric boundary region in term of the electron density. MAVEN Langmuir probe measurement (LPW) can estimate the electron density using the spacecraft environment. As MAVEN pass from the bow shock and sheath region into the magnetosphere the electron density often show a sharp gradient (the density jumps two orders of magnitudes in a few seconds). Comparing this to the data from particle instrument, the sharp electron density gradient was often associated with the transition of the characteristic energy of ions.Several hundreds of boundaries crossing by MAVEN allow us to investigate the statistical view of the boundary. We searched for a large electron density gradient as an indicator of the plasma boundary to identify the location of the ionospheric/solar wind plasma boundary. The results show that the many of the nightside boundaries locates close to the tail region of Mars forming elliptical shape of boundary. We will provide the empirical

  14. The zonal motion of equatorial plasma bubbles relative to the background ionosphere

    NASA Astrophysics Data System (ADS)

    Kil, Hyosub; Lee, Woo Kyoung; Kwak, Young-Sil; Zhang, Yongliang; Paxton, Larry J.; Milla, Marco

    2014-07-01

    The zonal motions of plasmas inside equatorial plasma bubbles are different from those in the background ionosphere. The difference was explained in terms of the tilt of bubbles by recent studies, but observational evidence of this hypothesis has not yet been provided. We examine this hypothesis and, at the same time, look for an alternative explanation on the basis of the coincident satellite and radar observations over Jicamarca (11.95°S, 76.87°W) in Peru. In the observations at premidnight by the first Republic of China satellite (altitude: 600 km, inclination: 35°), plasmas inside bubbles drift westward relative to ambient plasmas. The same phenomenon is identified by radar observations. However, the relative westward plasma motions inside bubbles occur regardless of the tilt of bubbles, and therefore, the tilt is not the primary cause of the deviation of the plasma motions inside bubbles. The zonal plasma motions in the topside are characterized by systematic eastward drifts, whereas the zonal motions of plasmas in the bottomside backscatter layer show a mixture of eastward and westward drifts. The zonal plasma motions inside backscatter plumes resemble those in the bottomside backscatter layer. These observations indicate that plasmas inside bubbles maintain the properties of the zonal plasma motions in the bottomside where the bubbles originate. With this assumption, the deviation of the zonal motions of plasmas inside bubbles from those of ambient plasmas is understood in terms of the difference of the zonal plasma flows in the bottomside and topside.

  15. Effects of finite plasma pressure on centrifugally driven convection in Saturn's magnetosphere

    NASA Astrophysics Data System (ADS)

    Liu, X.; Hill, T. W.

    2011-12-01

    We have previously shown simulation results for centrifugally driven plasma convection in Saturn's inner magnetosphere, using the Rice Convection Model, including a continuously active distributed plasma source, and effects of the Coriolis force and the pickup current. These simulations result in a quasi-steady state, in which fast, narrow inflow channels alternate with slower, wider outflow channels, consistent with Cassini Plasma Spectrometer observations. Comparison of different plasma source models indicates that the inner plasma source distribution is a key element in determining the plasma convection pattern. Previous simulations, however, did not include the effects of finite plasma pressure and the associated gradient-curvature drift. We will investigate here the effects of finite plasma pressure and gradient-curvature drift by giving the cold plasma a finite temperature. We will also add a source of hot tenuous plasma at the outer simulation boundary in an attempt to simulate the injection/dispersion events observed by Cassini.

  16. Ionospheric Convection in the Postnoon Auroral Oval: SuperDARN and Polar UVI Observations

    NASA Technical Reports Server (NTRS)

    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.

  17. Processes accompanying the charging of dust grains in the ionospheric plasma

    SciTech Connect

    Kopnin, S. I.; Morzhakova, A. A.; Popel, S. I.; Shukla, P. K.

    2011-08-15

    The influence of the neutral component of the dusty ionospheric plasma on the process of dust grain charging is analyzed. Microscopic ion fluxes onto a dust grain are calculated with allowance for the interaction with the neutral components of the ionospheric plasma for both negatively and positively charged dust grains. For the latter case, which takes place in the presence of intense UV or X-ray solar radiation, the electron heating caused by the photoelectric effect is also investigated. It is found that the efficiency of electron heating depends on the density of neutral particles. The altitudes at which these effects appreciably influence the charging of different types of nano- and microscale dust grains are determined. It is shown that these effects should be taken into account in describing noctilucent clouds, polar mesosphere summer echoes, and physical phenomena involving grains of meteoric origin.

  18. The Skylab barium plasma injection experiments. I - Convection observations

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Peek, H. M.

    1976-01-01

    Two barium-plasma injection experiments were carried out during magnetically active periods in conjunction with the Skylab 3 mission. The high-explosive shaped charges were launched near dawn on November 27 and December 4, 1973, UT. In both cases, the AE index was near 400 gammas, and extensive pulsating auroras covered the sky. The first experiment, Skylab Alpha, occurred in the waning phase of a 1000-gamma substorm, and the second, Skylab Beta, occurred in the expansive phase of an 800-gamma substorm. In both, the convection was generally magnetically eastward, with 100-km-level electric fields near 40 mV/m. However, in the Alpha experiment the observed orientation of the barium flux tube fit theoretical field lines having no parallel current, but the Beta flux-tube orientation indicated a substantial upward parallel sheet current.

  19. Design and construction of Keda Space Plasma Experiment (KSPEX) for the investigation of the boundary layer processes of ionospheric depletions

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Zhang, Zhongkai; Lei, Jiuhou; Cao, Jinxiang; Yu, Pengcheng; Zhang, Xiao; Xu, Liang; Zhao, Yaodong

    2016-09-01

    In this work, the design and construction of the Keda Space Plasma EXperiment (KSPEX), which aims to study the boundary layer processes of ionospheric depletions, are described in detail. The device is composed of three stainless-steel sections: two source chambers at both ends and an experimental chamber in the center. KSPEX is a steady state experimental device, in which hot filament arrays are used to produce plasmas in the two sources. A Macor-mesh design is adopted to adjust the plasma density and potential difference between the two plasmas, which creates a boundary layer with a controllable electron density gradient and inhomogeneous radial electric field. In addition, attachment chemicals can be released into the plasmas through a tailor-made needle valve which leads to the generation of negative ions plasmas. Ionospheric depletions can be modeled and simulated using KSPEX, and many micro-physical processes of the formation and evolution of an ionospheric depletion can be experimentally studied.

  20. An instrument for probe diagnostic of ionospheric plasma with compensation for spacecraft-charge effect

    SciTech Connect

    Ivanitskii, A.S.; Kashirin, A.I.; Chasovitin, Yu.K.; Chkalov, V.G.

    1994-10-01

    A device to probe ionospheric plasma that includes a simple circuit to eliminate the spacecraft-charge effect on the probe potential is described. It can record the current-voltage curves of the probe at particle currents of 15 nA-60 {mu}A over voltages of -2.5...+3.5 V when the voltage on the spacecraft surface with respect to the ambient potential is -3.5...+2.5 V.

  1. Magnetosphere--Ionosphere Coupling: Effects of Plasma Alfven Wave Relative Motion

    NASA Astrophysics Data System (ADS)

    Christiansen, P. J.; Dum, C. T.

    1989-06-01

    The introduction of relative perpendicular motion between a flux-tube supporting shear Alfven wave activity and the background plasma is studied in the context of the coupling of a wave generating region with a distant ionosphere. The results of a representative simulation, using an extended version of the code developed by Lysak & Dum (J. geophys. Res. 88, 365 (1983)), are used as a basis for interpreting some aspects of recent satellite observations.

  2. Magnetosphere-ionosphere coupling: effects of plasma Alfvén wave relative motion.

    NASA Astrophysics Data System (ADS)

    Christiansen, P. J.; Dum, C. T.

    The introduction of relative perpendicular motion between a flux-tube supporting shear Alfvén wave activity and the background plasma is studied in the context of the coupling of a wave generating region with a distant ionosphere. The results of a representative simulation, using an extended version of the code developed by Lysak & Dum, are used as a basis for interpreting some aspects of recent satellite observations.

  3. Modelling of the plasma environment surrounding 67P: the effect of the convective electric field on ion density profiles

    NASA Astrophysics Data System (ADS)

    Beth, Arnaud; Galand, Marina; Schwartz, Steven J.

    2016-04-01

    By following comet 67P/Churyumov-Gerasimenko along its orbit, Rosetta during its cruise is offering us the unique opportunity to understand the complex evolution of the comet with its environment. Although the coma is not bound at the surface, its photo-ionisation by solar extreme ultraviolet radiation creates a complex plasma environment which interacts with and is influenced by the solar wind. We consider the critical role played by collisionless processes (e.g. the effect of external electric and magnetic fields) in shaping the resulting ionospheric density profiles. In particular, the photo-ionisation of sublimated water molecules leads to the production of H_2O^+. These new ions are subjected to the electromagnetic environment of the solar wind in which they are born. In particular, the convective electric field Econv associated with the component of the solar wind flow perpendicular to the interplanetary magnetic field (i.e. Econv≈-vSWwedgeB) will strongly influence the dynamics of new ions and electrons and thus their density profiles around the comet. To lowest order that field can be described by the generalized Ohm's law of MHD. However, the small scales associated with 67P must be taken into consideration. We show that the convective electric field plays a key-role in the distribution of ions in the vicinity of the comet and in their transport. In particular, the physical size of the comet should be considered and the comet should not be reduced to a point source in the model. Finally, we will discuss the establishment of an induced ambipolar electric field on the ionospheric plasma to counteract the effect of Econv.

  4. Space weather. Ionospheric control of magnetotail reconnection.

    PubMed

    Lotko, William; Smith, Ryan H; Zhang, Binzheng; Ouellette, Jeremy E; Brambles, Oliver J; Lyon, John G

    2014-07-11

    Observed distributions of high-speed plasma flows at distances of 10 to 30 Earth radii (R(E)) in Earth's magnetotail neutral sheet are highly skewed toward the premidnight sector. The flows are a product of the magnetic reconnection process that converts magnetic energy stored in the magnetotail into plasma kinetic and thermal energy. We show, using global numerical simulations, that the electrodynamic interaction between Earth's magnetosphere and ionosphere produces an asymmetry consistent with observed distributions in nightside reconnection and plasmasheet flows and in accompanying ionospheric convection. The primary causal agent is the meridional gradient in the ionospheric Hall conductance which, through the Cowling effect, regulates the distribution of electrical currents flowing within and between the ionosphere and magnetotail. PMID:25013068

  5. Properties of the Auroral Zone Ionosphere Inferred Using Plasma Contactor Data From the International Space Station

    NASA Astrophysics Data System (ADS)

    Koontz, S. L.; Bering, E. A.; Evans, D. S.; Katz, I.; Gardner, B. M.; Suggs, R. M.; Minow, J. I.; Dalton, P. J.; Ferguson, D. C.; Hillard, G. B.; Counts, J. L.; Barsamian, H.; Kern, J.; Mikatarian, R.

    2001-12-01

    Comparison of the auroral electron precipitation maps produced by the NOAA POES satellite constellation with the flight path of the International Space Station (ISS) reveals that ISS regularly passes through the southern auroral oval south of Australia. During the first few months of 2001, ISS configuration and flight attitude were such that tensioning rods on the space station solar array masts could collect current from the ionosphere in the same way as a bare wire antenna or electrodynamic tether. The ISS has two plasma contactors that emit the electron currents needed to balance electron collection by surfaces such as the lattice of bare rods on the solar array masts. During this period, these electron currents exceeded 0.1 A at times. The largest currents were observed in the auroral oval south of Australia, often after orbital sunset. On the space station, the solar array 40 m long masts each have over 400 m of stainless steel tensioning rods. When subject to orbital vxBṡl induced potentials, the rods collect substantial currents from the ionosphere. Models of the mast collection processes based upon J. R. Sanmartin's bare wire collection theory have been incorporated into computer codes that integrate models of the station geometry, orbital motion, earth's magnetic field, and ionosphere to obtain plasma contactor emission currents. During the period being analyzed, the station flew in an orientation such that the masts were perpendicular to the orbital velocity vector, and parallel to the earth's surface. Maximum vxBṡl potentials are generated near the magnetic poles. The current drawn by the masts is linearly proportional to the plasma density. The plasma contactor emission current can be converted to an estimate of plasma density. These measurements show that the plasma density in the nighttime auroral ionosphere is frequently several times that predicted by the International Reference Ionosphere (IRI)-90 and IRI-2001 models. We will discuss how the

  6. Theory for modeling the equatorial evening ionosphere and the origin of the shear in the horizontal plasma flow

    SciTech Connect

    Haerendel, G.; Eccles, J.V.; Cakir, S. )

    1992-02-01

    Companion papers in this series present (1) the role of equatorial E region postsunset ionosphere, (2) the origin of horizontal plasma shear flow in the postsunset equatorial ionosphere (this paper), (3) the Colored Bubbles experiments results, and (4) computer simulations of artificial initiation of plasma density depletions (bubbles) in the equatorial ionosphere. Within this paper, equations describing the time evolution of the equatorial ionosphere are developed using flux tube integrated and flux tube weighted quantities which model the chemistry, dynamics, and electrodynamics of the equatorial ionosphere. The resulting two-dimensional set of equations can be used to investigate equatorial ionosphere. The resulting two-dimensional set of equations can be used to investigate equatorial electric fields neglecting small-scale phenomena ({lambda} < 1 km). An immediate result derived from the integrated current equations is an equation describing the physics of the shear in the horizontal flow of the equatorial plasma during the evening hours. The profile of the horizontal flow has three important contributing terms relating to the neutral wind dynamo, Hall conduction, and the equatorial electrojet current divergence. Using a one-dimensional model of the velocity shear equation and the integrated ionosphere transport equations, a time history of the development of the shear feature during postsunset hours is presented. The one-dimensional model results are compared to the velocity shear measurements from the Colored Bubbles experiments.

  7. Magnetosphere-ionosphere interactions: Near Earth manifestations of the plasma universe

    NASA Technical Reports Server (NTRS)

    Faelthammar, Carl-Gunne

    1986-01-01

    As the universe consists almost entirely of plasma, the understanding of astrophysical phenomena must depend critically on the understanding of how matter behaves in the plasma state. In situ observations in the near Earth cosmical plasma offer an excellent opportunity of gaining such understanding. The near Earth cosmical plasma not only covers vast ranges of density and temperature, but is the site of a rich variety of complex plasma physical processes which are activated as a results of the interactions between the magnetosphere and the ionosphere. The geomagnetic field connects the ionosphere, tied by friction to the Earth, and the magnetosphere, dynamically coupled to the solar wind. This causes an exchange of energy an momentum between the two regions. The exchange is executed by magnetic-field-aligned electric currents, the so-called Birkeland currents. Both directly and indirectly (through instabilities and particle acceleration) these also lead to an exchange of plasma, which is selective and therefore causes chemical separation. Another essential aspect of the coupling is the role of electric fields, especially magnetic field aligned (parallel) electric fields, which have important consequences both for the dynamics of the coupling and, especially, for energization of charged particles.

  8. Theoretical study of the ionospheric plasma cave in the equatorial ionization anomaly region

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Tsung; Lin, C. H.; Chen, C. H.; Liu, J. Y.; Huba, J. D.; Chang, L. C.; Liu, H.-L.; Lin, J. T.; Rajesh, P. K.

    2014-12-01

    This paper investigates the physical mechanism of an unusual equatorial electron density structure, plasma cave, located underneath the equatorial ionization anomaly by using theoretical simulations. The simulation results provide important new understanding of the dynamics of the equatorial ionosphere. It has been suggested previously that unusual E>⇀×B>⇀ drifts might be responsible for the observed plasma cave structure, but model simulations in this paper suggest that the more likely cause is latitudinal meridional neutral wind variations. The neutral winds are featured by two divergent wind regions at off-equator latitudes and a convergent wind region around the magnetic equator, resulting in plasma divergences and convergence, respectively, to form the plasma caves structure. The tidal-decomposition analysis further suggests that the cave related meridional neutral winds and the intensity of plasma cave are highly associated with the migrating terdiurnal tidal component of the neutral winds.

  9. Topside Ionosphere Plasma Bubbles Seen in He+ Density: Results and Problems

    NASA Astrophysics Data System (ADS)

    Sidorova, Larisa; Filippov, Sergey

    He (+) density depletions, considered as fossil equatorial plasma bubble signatures, were involved in this study. They are usually detected in the topside ionosphere (approx. 1000 km) deeply inside the plasmasphere (L=1.3-3). a) The question about an opportunity to detect the topside plasma bubbles of equatorial origin in their separate plasma component (He (+) ) is investigated. There are the indications [Sidorova, ASR, 2004, 2007; Sidorova and Filippov, JASTP, 2012] that there is genetic connection between the He (+) density depletions and the equatorial plasma bubbles. For validation of this idea the characteristic times of the main photochemical and electro-dynamical processes, in which the plasma bubbles and their minor ion component (He (+) ) are involved, have been calculated and compared. The model estimations, obtained in SAMIS3 (3D model of equatorial spread F) and kindly presented by J. Huba (USA), are also used for the investigation. It was revealed that the plasma bubbles, reaching the “ceiling” heights, can exist within 2-3 days and that there is principal opportunity to observe them in the separate plasma component (He (+) ). (b) The longitudinal statistics of the He (+) density depletions (P), calculated for all seasons and both hemispheres (20-50(°) INVLAT), were obtained. It was revealed that the most of the P plots have “wave-like” structure with well-defining four peaks. The peaks are the most pronounced in the NH during March equinox/December solstice and in the SH during March equinox/June solstice. Similar wave number 4 longitudinal structure has recently been found in the low-latitude ionosphere density distribution [Immel et al., GRL, 2006; England et al., GRL, 2006; Jin et al., JGR, 2008]. It is assumed that the longitudinal plasma density variations appear due to the modulated vertical Е×В drift. It is supposed that solar thermal tides excited in the troposphere induce zonal perturbation electric fields, which are added to the

  10. Plasma Instability Growth Rates in the F-Region Cusp Ionosphere

    NASA Astrophysics Data System (ADS)

    Moen, J. I.; Daabakk, Y.; Oksavik, K.; Clausen, L.; Bekkeng, T. A.; Abe, T.; Saito, Y.; Baddeley, L. J.; Lorentzen, D. A.; Sigernes, F.; Yeoman, T. K.

    2014-12-01

    There are at least two different micro-instability processes that applies to the F-region cusp/polar cap ionosphere. These are the Gradient Drift Instability (GDI) and the Kelvin Helmholtz Instability (KHI). Due to space weather effects on radio communication and satellite signals it is of practical interest to assess the relative importance of these two instability modes and to quantify their growth rates. The Investigation of Cusp Irregularities (ICI) rocket program has been developed to investigate these plasma instabilities and formation scintillation irregularities. High resolution measurements are critical to get realistic quantities on the growth rates. The results achieved so far demonstrates that cusp ionosphere precipitation can give rise to km scale plasma structures on which grow rates are down to a few tens of seconds compared to earlier measures of ten minutes based on ground observations. This has to do with the spatial resolution required for these measurements. Growth rates for the KHI instability is found to be of the same order, which is consistent with growth rates calculated from the EISCAT Svalbard Radar. I.e. both instability modes can be highly efficient in the cusp ionosphere.

  11. HF Propagation Effects Caused by an Artificial Plasma Cloud in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Joshi, D. R.; Groves, K. M.; McNeil, W. J.; Caton, R. G.; Parris, R. T.; Pedersen, T. R.; Cannon, P. S.; Angling, M. J.; Jackson-Booth, N. K.

    2014-12-01

    In a campaign carried out by the NASA sounding rocket team, the Air Force Research Laboratory (AFRL) launched two sounding rockets in the Kwajalein Atoll, Marshall Islands, in May 2013 known as the Metal Oxide Space Cloud (MOSC) experiment to study the interactions of artificial ionization and the background plasma and measure the effects on high frequency (HF) radio wave propagation. The rockets released samarium metal vapor in the lower F-region of the ionosphere that ionized forming a plasma cloud that persisted for tens of minutes to hours in the post-sunset period. Data from the experiments has been analyzed to understand the impacts of the artificial ionization on HF radio wave propagation. Swept frequency HF links transiting the artificial ionization region were employed to produce oblique ionograms that clearly showed the effects of the samarium cloud. Ray tracing has been used to successfully model the effects of the ionized cloud. Comparisons between observations and modeled results will be presented, including model output using the International Reference Ionosphere (IRI), the Parameterized Ionospheric Model (PIM) and PIM constrained by electron density profiles measured with the ALTAIR radar at Kwajalein. Observations and modeling confirm that the cloud acted as a divergent lens refracting energy away from direct propagation paths and scattering energy at large angles relative to the initial propagation direction. The results confirm that even small amounts of ionized material injected in the upper atmosphere can result in significant changes to the natural propagation environment.

  12. Comparison of the ionospheric plasma turbulence over seismic and equatorial regions.

    NASA Astrophysics Data System (ADS)

    Kosciesza, M.; Blecki, J.; Parrot, M.; Wronowski, R.

    2012-04-01

    Many strong earthquakes which are objects of interest in investigations of the changes registered in the electric field in the ELF frequency range (1 Hz - 1250 Hz) in the ionospheric plasma, occurs in the equatorial region. In order to determine, if the observed disturbances are connected with the coupling between the ground and the ionosphere in the seismic active region, it is necessary to analyse and compare plasma instability phenomena occurring in the equatorial F-region ionosphere and are known as equatorial spread F (ESF) to changes before earthquakes because their character is very similar. The aim of this paper is the analysis of changes in the electromagnetic ELF field, registered by the French micro-satellite DEMETER over epicentres of three selected strong earthquakes with magnitude bigger than 6, which took place in: Sichuan, Chile and Haiti. A comparison between those cases and changes observed by the same satellite over the equatorial region in the similar time of year is presented. The analysis of the data, was conducted with the Fourier, wavelet and bispectral methods. The last one gives answer to question, whether the changes localized with the spectral analysis are nonlinear. Further processing consists the determination of the power spectrum and its slope, which allows to determine the type of turbulence which was inducted by the three wave interaction. The last stage of the presented research, was finding the characteristic remarks of changes, by calculation of the probability density function (PDF) and calculation of its characteristic values such as kurtosis and skewness.

  13. GPS and in situ Swarm observations of the equatorial plasma density irregularities in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Zakharenkova, Irina; Astafyeva, Elvira; Cherniak, Iurii

    2016-07-01

    Here we study the global distribution of the plasma density irregularities in the topside ionosphere by using the concurrent GPS and Langmuir probe measurements onboard the Swarm satellites. We analyze 18 months (from August 2014 till January 2016) of data from Swarm A and B satellites that flew at 460 and 510 km altitude, respectively. To identify the occurrence of the ionospheric irregularities, we have analyzed behavior of two indices ROTI and RODI based on the change rate of total electron content and electron density, respectively. The obtained results demonstrate a high degree of similarities in the occurrence pattern of the seasonal and longitudinal distribution of the topside ionospheric irregularities derived from both types of the satellite observations. Among the seasons with good data coverage, the maximal occurrence rates for the post-sunset equatorial irregularities reached 35-50 % for the September 2014 and March 2015 equinoxes and only 10-15 % for the June 2015 solstice. For the equinox seasons the intense plasma density irregularities were more frequently observed in the Atlantic sector, for the December solstice in the South American-Atlantic sector. The highest occurrence rates for the post-midnight irregularities were observed in African longitudinal sector during the September 2014 equinox and June 2015 solstice. The observed differences in SWA and SWB results could be explained by the longitude/LT separation between satellites, as SWB crossed the same post-sunset sector increasingly later than the SWA did.

  14. Processes in complex (dusty) plasmas in the midlatitude ionosphere during high-speed meteor showers

    NASA Astrophysics Data System (ADS)

    Popel, S. I.; Kopnin, S. I.

    2007-08-01

    The emission low-frequency lines in the frequency range of 12 to 60 Hz recorded [1] against the radio-frequency noise background during high-speed (the speed of entry into the atmosphere is about 70 km/s) meteor showers (Perseids, Orionids, Leonids, and Gemenids) are shown to serve as an evidence of the existence of complex (dusty) plasmas in the midlatitude ionosphere. The mechanism for generating the radio-frequency noises in the frequency range of 12 to 60 Hz is shown to be as follows. During Perseid, Orionid, Gemenid, and Leonid meteor showers, the meteors are ablated at altitudes of 70-130 km, depending on their sizes and initial velocities. The result of ablation is the production of supersaturated vapors of such metals as sodium, calcium, magnesium, etc., which then condense into nanometer-to-micrometer-sized secondary (dust) grains of cosmic origin. The grains can acquire an electric charge because of the action of unbalanced electron and ion currents and because of the photoelectric effect resulting from solar light. As an electromagnetic wave propagates in a complex (dusty) plasma in the ionosphere, the modulational interaction [2] excites low-frequency electrostatic waves at characteristic frequencies close to those of the dust acoustic waves, with the result that electromagnetic waves may become modulated. It is the low-frequency component of the wave modulated against the ionospheric noise background that is recorded at the Earth's surface. Our theoretical results are shown to agree well with the data on ionospheric plasma noise observed during meteor showers. We show also that along with the low-frequency component of modulated electromagnetic waves, the lines of infrasonic waves generated in the meteoric precipitation regions should be recorded as well. The infrasonic waves are generated by the dust acoustic waves interacting with neutrals. We determine the conditions for generation of both linear and nonlinear infrasonic waves by the dust acoustic

  15. On the effect of BUM generation enhancement revealed using the scheme of additional heating of ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Erukhimov, L. M.; Komrakov, G. P.; Sergeev, E. N.; Thidé, B.; Bernhardt, P. A.; Wagner, L. S.; Goldstein, J. A.; Selcher, G.

    1997-05-01

    We present measured characteristics of the artificial ionospheric radio emission (AIRE), which were obtained experimentally using additional heating of the ionospheric F-region by O-polarized waves. It is shown that the observed enhancement of intensity of the broad upshifted maximum (BUM) of the AIRE can result from the influence of electrons accelerated in the plasma: esonance region on its generation. An empirical model of the phenomenon observed is developed. It is concluded from experimental results that the BUM has a complex structure and only one of its components produces the above emission enhancement. We show the possibility of using the AIRE in additional heating of ionospheric plasma for diagnostics of artificial ionospheric turbulence and investigation of the features of perturbation propagation along the geomagnetic field lines.

  16. Radio Wave Reflections from Magnetized Plasma Bulges in the Martian Ionosphere

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Nielsen, E.; Xiao, L.; Liang, Y.

    2011-12-01

    In this paper we propose a quantitative explanation of a special type of radio wave reflection phenomena observed by MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding), in light of the cold plasma theory. The phenomena in question appear as a type of traces in the AIS (Active Ionosphere Sounding) ionograms. The traces show the following characteristics: (1) They may appear only when the spacecraft is near to a magnetic cusp region (around 300km altitude) on dayside; (2) They are "C"-shaped curves, with their open ends pointing to the increasing frequency direction. Obviously, these traces represent 'reflection pairs' (two echoes corresponding to one transmission from the antenna). The two echoes of a 'pair' have approximately the same time delay at the lowest propagating frequency, and have increasing time delay separation with increasing wave frequency; (3) Their positions and sizes in ionograms (i.e., their frequency ranges and time delay ranges) change regularly with spacecraft motion; (4) They represent quite rare events, since they are clearly observed only in a few orbit segments among thousands of orbits of Mars Express. In order to investigate the origin of these features, we employ a 2D spatial configuration model of the magnetized plasma bulge to simulate the behavior of the AIS radio waves. In the model the magnetic field is assumed to be a deformed vertical cylinder (corresponding to the patched crustal field of Mars), with its transverse size expanding upward. Magnetic flux density decreases upward and sideward continuously into a low background field value (while the total flux is conserved). Electron density is positively related to the field flux density, meanwhile decreases upward in an exponential manner. Equilibrium between magnetic pressure and plasma pressure is assumed to hold the density bulge. A ray tracing method based on the cold plasma dispersion relation is used to produce artificial ionograms. We find that under some

  17. Ionosphere/thermosphere heating determined from dynamic magnetosphere-ionosphere/thermosphere coupling

    NASA Astrophysics Data System (ADS)

    Tu, Jiannan; Song, Paul; Vasyliūnas, Vytenis M.

    2011-09-01

    Ionosphere/thermosphere heating driven by magnetospheric convection is investigated through a three-fluid inductive (including Faraday's law) approach to describing magnetosphere-ionosphere/thermosphere coupling, for a 1-D stratified ionosphere/thermosphere in this initial study. It is shown that the response of the ionosphere/thermosphere and thus the heating is dynamic and height-dependent. The heating is essentially frictional in nature rather than Joule heating as commonly assumed. The heating rate reaches a quasi-steady state after about 25 Alfvén travel times. During the dynamic period, the heating can be enhanced and displays peaks at multiple times due to wave reflections. The dynamic heating rate can be more than twice greater than the quasi-steady state value. The heating is strongest in the E-layer but the heating rate per unit mass is concentrated around the F-layer peak height. This implies a potential mechanism of driving O+ upflow from O+ rich F-layer. It is shown that the ionosphere/thermosphere heating caused by the magnetosphere-ionosphere coupling can be simply evaluated through the relative velocity between the plasma and neutrals without invoking field-aligned currents, ionospheric conductance, and electric field. The present study provides understanding of the dynamic magnetosphere-ionosphere/thermosphere coupling from the ionospheric/thermospheric view in addition to magnetospheric perspectives.

  18. Transport processes and distribution of plasma in the ionosphere during total solar eclipses

    NASA Astrophysics Data System (ADS)

    Chukwuma, Victor

    2016-07-01

    The effect of solar eclipse on the ionospheric F2 layer does not appear to depend only on the changes in the electron density. In this regards therefore, we have investigated the transport term process and the distribution F2 plasma during three total solar eclipses (TSE) at low- and mid-latitude. Particularly, the diurnal changes in the NmF2 and hmF2 during these spectacular events, as recorded by the ionosondes situated along the path of solar eclipses, which are within the obscuration percentage of 59-90% were investigated. Presently, our results show that NmF2 decreased during the eclipse window, as a consequence of the variation in the local solar radiation in regions under investigation. However, at mid-latitude, the distribution of F2 plasma was dominated by diffusion mechanisms which determined the height at which the F2 peak formed and were related to the changes in thermospheric composition. While at low-latitude the plasma distribution during TSE appeared to depend on combined effect of solar ionizing radiation (SIR) and the background nighttime ionospheric instabilities/irregularities mechanism. The downward/upward transport processes of the plasma appear to correspond with the drifting of the diffusion mechanisms and suffered a comparable variation with the SIR. Furthermore, at low-latitude ionosphere the transport process is controlled by the equatorial electric field. It is also observed that the eastward/westward movement of the equatorial electric field during the eclipse phase was connected to the upward/downward movement of the vertical transport. In conclusion, our results appear to indicate that eclipse effects increased with increase in latitude and the time lag decreases with increase in latitude.

  19. Integrated Multi-Point Space Plasma Measurements With Four Ionospheric Satellites

    NASA Astrophysics Data System (ADS)

    Siefring, C. L.; Bernhardt, P. A.; Selcher, C.; Wilkens, M. R.; McHarg, M. G.; Krause, L.; Chun, F.; Enloe, L.; Panholzer, R.; Sakoda, D.; Phelps, R.; D Roussel-Dupre, D.; Colestock, P.; Close, S.

    2006-12-01

    The STP-1 launch scheduled for late 2006 will place four satellites with ionospheric plasma diagnostics into the same nearly circular orbit with an altitude of 560 km and inclination of 35.4°. The satellites will allow for unique multipoint measurements of ionospheric scintillations and their causes. Both the radio and in-situ diagnostics will provide coverage of low- and mid-latitudes. The four satellites, STPSat1, NPSat1, FalconSat3, and CFE will follow the same ground-track but because of drag and mass differences their relative velocities will be different and vary during the lifetime of the satellites. The four satellites will start close together; separate over a few months and coming back together with near conjunctions at six and eight months. Two satellite conjunctions between NPSat1 and STPSat1 will occur most often, approximately one month apart at the end of the mission. STPSat1 is equipped with CITRIS (sCintillation and TEC Receiver In Space) which will measure scintillations in the VHF, UHF and L-band along with measuring Total Electron Content (TEC) along the propagation path. NPSat1 will carry a three-frequency CERTO (Coherent Electromagnetic Radio TOmography) Beacon which broadcasts phase-coherent signals at 150.012 MHz, 400.032 MHz, and 1066.752 MHz. CITRIS will be able to measure TEC and Scintillations along the orbital path (propagation path from NPSat1 to STPSat1) as well as between the CITRIS and the ground. NPSat1 carries electron and ion saturation Langmuir Probes, while FalconSat3 carries the FLAPS (FLAt Plasma Spectrometer) and PLANE (Plasma Local Anomalous Noise Environment). The in-situ diagnostic complement the CITRIS/CERTO radio techniques in many ways. The CIBOLA Flight Experiment (CFE) contains a wide band receiver covering 100 to 500 MHz. The CFE data can be processed to show distortion of wide-band modulations by ionospheric irregularities. CFE and CITRIS can record ground transmissions from the French DORIS beacons which radiate

  20. Model study of the effects of gravity wave dissipation on the thermosphere and ionosphere from deep convection worldwide 15-27 June 2009

    NASA Astrophysics Data System (ADS)

    Vadas, S.; Liu, H.

    2013-12-01

    In this paper, we discuss the methods and results of a global modeling study for the effect of deep convection on the thermosphere and ionosphere through the dissipation of atmospheric gravity waves (GWs). The selected time period is 15-27 June 2009, during the recent extreme solar minimum. The convective plumes which overshot the tropopause are identified from IR images obtained by the instruments on 5 satellites covering Earth (from west to east: GOES11, GOES12, M9, M7, and MTS). We model the excitation of GWs from these plumes, and ray trace them into the thermosphere using our ray trace model which has been upgraded to span the Earth. We then calculate the forcings/heatings/coolings which result when and where these GWs dissipate in the thermosphere. We input these forcings/heatings/coolings into the global TIME-GCM, and re-run the model. In this paper, we discuss these methods and models in detail. We then discuss how the thermosphere and ionosphere responded to the dissipation of these convectively-generated GWs worldwide.

  1. Radial convection of finite ion temperature, high amplitude plasma blobs

    SciTech Connect

    Wiesenberger, M. Kendl, A.; Madsen, J.

    2014-09-15

    We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very well described by the ratio of the ion gyroradius to the characteristic gradient scale length of the blob. We compare the global gyrofluid model with a partly linearized local model. For low ion temperatures, we find that simulations of the global model show more coherent blobs with an increased cross-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in the global simulations than in the local ones. When the ion temperature is comparable to the electron temperature, global blob simulations show a reduced blob coherence and a decreased cross-field transport in comparison with local blob simulations.

  2. Scintillation of radio astronomical sources due to anisotropic inhomogeneities in the ionospheric plasma

    SciTech Connect

    Bezrodnyi, V.G.

    1988-02-01

    We have investigated the properties of scintillation of sources of cosmic radio emission due to inhomogeneities in the ionospheric F-region. The inhomogeneities are elongated along the geomagnetic field lines. We show that when the line of sight coincides with the magnetic field direction, we should observe an increase in the magnitude of the scintillation index. The amount of the increase, as well as the angular range in which it occurs, depend on the explicit shape of the spectrum of spatial scales of the inhomogeneities. We have given consideration to models which have been adopted in the literature for three-dimensional and two-dimensional anisotropy in the ionospheric turbulence. Based on this analysis, we propose a diagnostic method for the inhomogeneous ionospheric plasma. It is based on multifrequency measurements of the scintillation index of radio astronomical sources which culminate near the direction of the geomagnetic field lines at the latitude of the observing point. We establish the limits which are imposed on our proposed method because of the finite dimensions of the sources.

  3. UCB current detector experiment on Swedish auroral payloads. [ionospheric current and plasma flow measurements

    NASA Technical Reports Server (NTRS)

    Mozer, F.

    1974-01-01

    A split Langmuir probe has been developed to make in situ measurements of ionospheric current density and plasma bulk flow. The probe consists of two conducting elements that are separated by a thin insulator that shield each other over a 2 pi solid angle, and that are simultaneously swept from negative to positive with respect to the plasma. By measuring the current to each plate and the difference current between plates, information is obtained on the plasma's current density, bulk flow, electron temperature, and density. The instrument was successfully flown twice on sounding rockets into auroral events. Measurement data indicate that the total auroral current configuration is composed of several alternating east and west electrojets associated with several alternating up and down Birkeland currents.

  4. Suprathermal plasma analyzer for the measurement of low-energy electron distribution in the ionosphere.

    PubMed

    Shimoyama, M; Oyama, K-I; Abe, T; Yau, A W

    2011-07-01

    It is commonly believed that an energy transfer from thermal to suprathermal electrons (ionosphere. However, observation of electron energy spectrum in this energy range is quite limited because of technical difficulties of measurement. We have developed an instrument to measure electron energy distribution from thermal to suprathermal energy continuously with high-energy resolution of about 0.15 eV. The measurement principle is based on the combination of a retarding potential analyzer with a channel electron multiplier (CEM) and the Druyvesteyn method, which derives energy distribution from the current-voltage characteristics. The capability of detecting plasma space potential enables absolute calibration of electron energy. The instrument with a small vacuum pump, which is required for the CEM to work in low-vacuum region, was first successfully tested by a sounding rocket S-310-37 in the ionospheric E region. The instrument is expected to provide new opportunities to measure energy distribution of thermal and non-thermal electrons in low-density plasma, where a Langmuir probe cannot measure electron temperature because of low plasma density. PMID:21806205

  5. Suprathermal plasma analyzer for the measurement of low-energy electron distribution in the ionosphere

    SciTech Connect

    Shimoyama, M.; Yau, A. W.; Oyama, K.-I.; Abe, T.

    2011-07-15

    It is commonly believed that an energy transfer from thermal to suprathermal electrons (ionosphere. However, observation of electron energy spectrum in this energy range is quite limited because of technical difficulties of measurement. We have developed an instrument to measure electron energy distribution from thermal to suprathermal energy continuously with high-energy resolution of about 0.15 eV. The measurement principle is based on the combination of a retarding potential analyzer with a channel electron multiplier (CEM) and the Druyvesteyn method, which derives energy distribution from the current-voltage characteristics. The capability of detecting plasma space potential enables absolute calibration of electron energy. The instrument with a small vacuum pump, which is required for the CEM to work in low-vacuum region, was first successfully tested by a sounding rocket S-310-37 in the ionospheric E region. The instrument is expected to provide new opportunities to measure energy distribution of thermal and non-thermal electrons in low-density plasma, where a Langmuir probe cannot measure electron temperature because of low plasma density.

  6. Observations of the plasma environment during an active ionospheric ion beam injection experiment

    NASA Technical Reports Server (NTRS)

    Arnoldy, R. L.; Pollock, C. J.; Cahill, L. J., Jr.; Erlandson, R. E.; Kintner, P. M.

    1990-01-01

    Several sounding rocket flights have been used to clarify the electrodynamics of neutral beam releases of Ar ions in the upper ionosphere, by varying the Ar's point of release with respect to the diagnostic payload. A volume of 10-m radius centered on the Ar release payload is measured for broadband wave activity; the superthermal neutralizing beam electrons become magnetized in this volume for across-field plasma releases, and ambient electrons are accelerated to energies of several hundred eV. This is speculated to be due to wave turbulence rather than payload-neutralization.

  7. Study of plasma natural convection induced by electron beam in atmosphere [

    SciTech Connect

    Deng, Yongfeng Han, Xianwei; Tan, Yonghua

    2014-06-15

    Using high-energy electron beams to ionize air is an effective way to produce a large-size plasma in the atmosphere. In particular, with a steady-state high power generator, some unique phenomena can be achieved, including natural convection of the plasma. The characteristics of this convection are studied both experimentally and numerically. The results show that an asymmetrical temperature field develops with magnitudes that vary from 295 K to 389 K at a pressure of 100 Torr. Natural convection is greatly enhanced under 760 Torr. Nevertheless, plasma transport is negligible in this convection flow field and only the plasma core tends to move upward. Parameter analysis is performed to discern influencing factors on this phenomenon. The beam current, reflecting the Rayleigh number Ra effect, correlates with convection intensity, which indicates that energy deposition is the underlying key factor in determining such convections. Finally, natural convection is concluded to be an intrinsic property of the electron beam when focused into dense air, and can be achieved by carefully adjusting equipment operations parameters.

  8. Modelling ionospheric density structures

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Sojka, J. J.

    1989-01-01

    Large-scale density structures are a common feature in the high-latitude ionsphere. The structures were observed in the dayside cusp, polar cap, and nocturnal auroral region over a range of altitudes, including the E-region, F-region and topside ionosphere. The origins, lifetimes and transport characteristics of large-scale density structures were studied with the aid of a three-dimensional, time-dependent ionospheric model. Blob creation due to particle precipitation, the effect that structured electric fields have on the ionosphere, and the lifetimes and transport characteristics of density structures for different seasonal, solar cycle, and interplanetary magnetic field (IMF) conditions were studied. The main conclusions drawn are: (1) the observed precipitation energy fluxes are sufficient for blob creation if the plasma is exposed to the precipitation for 5 to 10 minutes; (2) structured electric fields produce structured electron densities, ion temperatures, and ion composition; (3) the lifetime of an F-region density structure depends on several factors, including the initial location where it was formed, the magnitude of the perturbation, season, solar cycle and IMF; and (4) depending on the IMF, horizontal plasma convection can cause an initial structure to break up into multiple structures of various sizes, remain as a single distorted structure, or become stretched into elongated segments.

  9. Physics of planetary ionospheres

    NASA Technical Reports Server (NTRS)

    Bauer, S. J.

    1973-01-01

    The fundamental physical and chemical processes in an idealized planetary ionosphere are considered as a general abstraction, with actual planetary ionospheres representing special cases. After describing the structure of the neutral atmospheres (the barosphere, the thermosphere, and the exosphere) and noting the principal ionizing radiations responsible for the formation of planetary ionospheres, a detailed study is made of the thermal structure of these ionospheres and of the chemical processes and plasma-transport processes occurring in them. The features of equilibrium and realistic models of planetary ionospheres are discussed, and an attempt is made to determine the extent of these ionospheres. Considering the ionosphere as a plasma, a plasma kinetic approach is developed for determining the effects of interactions between individual particles and waves in this plasma. The use of remote-sensing radio techniques and direct measurement or in situ techniques is discussed. Finally, the observed properties of the ionospheres of the Earth, Mars, Venus, and Jupiter are reviewed.

  10. On the equatorial transport of Saturn's ionosphere as driven by a dust-ring current system

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.; Mendis, D. A.

    1983-03-01

    The diurnal modulation of the dust ring current of Saturn's D-ring causes field-aligned Birkeland currents to flow near the dawn and dusk terminators and close across the mid-latitude ionosphere. One consequence of this current system is the establishment of a global convection pattern in the equatorial outer ionosphere. Outward motion of the dayside ionospheric plasma as well as the corresponding absorption effect of the inner ring system might be one physical cause of the depletion of the ionospheric content of Saturn.

  11. Does the Precipitation of Solar Wind Plasma Cause the Ionospheric Upwellings Detected by MARSIS on the Dayside of Mars?

    NASA Astrophysics Data System (ADS)

    Dieval, C.; Morgan, D. D.; Andrews, D. J.; Duru, F.; Gurnett, D. A.

    2014-12-01

    The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the Mars Express spacecraft possesses an ionospheric mode, which is used for local and remote sounding measurements of the Martian topside ionosphere. Ideally, the sounding pulse transmitted by MARSIS gives a vertical reflection from the horizontally stratified ionosphere, down to the ionospheric peak. In practice, this is usually the case, however oblique reflections are also detected. These oblique reflections are often found in regions where the remanent crustal magnetic field is nearly vertical and the sources of reflections are often at a higher apparent altitude than the surrounding ionosphere for the same electron density level. There are recurring observations of such ionospheric upwellings during repeated passes of Mars Express above certain regions over time periods of tens of days. An increased ionospheric scale height seems to create these plasma bulges. A possible cause is a localized heating of the neutral atmosphere due to the entrance of solar wind plasma through the magnetic cusps. We test this explanation by using in situ measurements of electron energy distributions made by the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) onboard Mars Express. The statistical study considers dayside oblique echoes (solar zenith angle ≤ 90°) with spacecraft altitude ≤1100 km, for orbits with sufficient MARSIS data coverage and corresponding to a criterion of repetitive passes above a given region. We keep only oblique echoes which are no further below than 10 km in apparent altitude compared to the surrounding ionosphere (most of the cases), to ensure the echoes most likely come from near the vertical direction, at the time of closest approach. Finally we take the oblique echoes with simultaneous ASPERA-3 data, with short time intervals (up to 2 minutes) before and after the time of closest approach. This leaves 761 oblique echoes. The intervals are then manually

  12. New ISTP Solar Max: A Multi-Spacecraft Study of the Flow of Ionospheric Plasma

    NASA Technical Reports Server (NTRS)

    Chappell, Charles R.

    2003-01-01

    The unique instrumentation on the Polar satellite combined with the simultaneous measurement of different parts of the magnetosphere with multiple satellites make possible the study of magnetospheric processes in a special way. In particular, the study of the ionospheric supply of plasma to the magnetosphere can by accomplished to give important results on the plasmas which drive the dynamics of the magnetosphere. This study concentrated on the period of September to December, 2001 in which the Polar orbit had precessed to the point that the line of apsides was near the equatorial plane. This unique orbital configuration enabled the TIDE instrument to measure outflowing ions across the polar cap and then transit the magnetotail lobes and observe the dramatic change in plasma characteristics as the satellite entered the plasma sheet. Contact was made with investigators on the Cluster and Geotail satellite missions and corresponding time frames were studied in the data. There were two approximate conjunctions between Polar and Geotail and data were compared to look for features which might be related. The higher energy concentration of the Geotail instrument made direct comparisons with TIDE difficult, and the Cluster measurements did not surface any cases that corresponded closely in space and time. There were, however, many interesting aspects of the Polar orbits which permitted the observation of the changing ionospheric outflowing plasma characteristics. As in earlier measurements, the ionospheric plasma could be seen flowing up the magnetic field lines out of the northern and southern polar caps. Its energy suggested a polar wind origin energized by the centrifugal acceleration of flow through the polar cusp. The roughly 10eV ions then moved out into the lobes of the magnetotail where they could be seen flowing toward the plasma sheet in both the northern and southern magnetotail lobes. There was also a double field-aligned region of warm ions observed just

  13. Altitudinal variability of quiet-time plasma drifts in the equatorial ionosphere

    NASA Astrophysics Data System (ADS)

    Hui, Debrup

    The plasma drifts or electric fields and their structures in the ionosphere affect the accuracy of the present-day space-based systems. For the first time, we have used ionospheric plasma drift data from Jicamarca radar measurements to study the climatology of altitudinal variations of vertical and zonal plasma drifts in low latitudes during daytime. We used data from 1998 to 2014 to derive these climatological values in bimonthly bins from 150 km to 600 km. For the vertical plasma drifts, we observed the drifts increasing with altitudes in the morning and slowly changing to drifts decreasing with altitude in the afternoon hours. The drifts change mostly linearly from E- to F-region altitudes except in the morning hours of May-June when the gradients are very small. The zonal drifts show a highly nonlinear increase in the westward drifts at the lower altitudes and then increase slowly at the higher altitudes. We see a break in the slopes at lower altitudes during the morning hours of March-April and May-June. The E-region zonal drifts, unlike vertical drifts, show a very large variability compared to F-region drifts. We also explored the altitudinal profiles of vertical drifts during late afternoon and evening hours when the electrodynamic properties in the ionosphere change rapidly. For the first time using drifts up to 2000 km, we have shown the drifts increase and decrease below and above the F-region peak before becoming height independent. These structures arise to satisfy the curl-free condition of electric fields in low latitudes. The altitudinal gradients of vertical drifts are balanced by a time derivative of the zonal drifts to satisfy the curl-free condition of electric fields. We have shown how these structures evolve with local time around the dusk sector and change with solar flux. During solar minimum, the peak region can go well below 200 km. The present-day electric field models do not incorporate these gradients, particularly in the evening

  14. Convective plasma stability consistent with MHD equilibrium in magnetic confinement systems with a decreasing field

    SciTech Connect

    Tsventoukh, M. M.

    2010-10-15

    A study is made of the convective (interchange, or flute) plasma stability consistent with equilibrium in magnetic confinement systems with a magnetic field decreasing outward and large curvature of magnetic field lines. Algorithms are developed which calculate convective plasma stability from the Kruskal-Oberman kinetic criterion and in which the convective stability is iteratively consistent with MHD equilibrium for a given pressure and a given type of anisotropy in actual magnetic geometry. Vacuum and equilibrium convectively stable configurations in systems with a decreasing, highly curved magnetic field are calculated. It is shown that, in convectively stable equilibrium, the possibility of achieving high plasma pressures in the central region is restricted either by the expansion of the separatrix (when there are large regions of a weak magnetic field) or by the filamentation of the gradient plasma current (when there are small regions of a weak magnetic field, in which case the pressure drops mainly near the separatrix). It is found that, from the standpoint of equilibrium and of the onset of nonpotential ballooning modes, a kinetic description of convective stability yields better plasma confinement parameters in systems with a decreasing, highly curved magnetic field than a simpler MHD model and makes it possible to substantially improve the confinement parameters for a given type of anisotropy. For the Magnetor experimental compact device, the maximum central pressure consistent with equilibrium and stability is calculated to be as high as {beta} {approx} 30%. It is shown that, for the anisotropy of the distribution function that is typical of a background ECR plasma, the limiting pressure gradient is about two times steeper than that for an isotropic plasma. From a practical point of view, the possibility is demonstrated of achieving better confinement parameters of a hot collisionless plasma in systems with a decreasing, highly curved magnetic field

  15. Convection of Plasmaspheric Plasma into the Outer Magnetosphere and Boundary Layer Region: Initial Results

    NASA Technical Reports Server (NTRS)

    Ober, Daniel M.; Horwitz, J. L.; Gallagher, D. L.

    1998-01-01

    We present initial results on the modeling of the circulation of plasmaspheric- origin plasma into the outer magnetosphere and low-latitude boundary layer (LLBL), using a dynamic global core plasma model (DGCPM). The DGCPM includes the influences of spatially and temporally varying convection and refilling processes to calculate the equatorial core plasma density distribution throughout the magnetosphere. We have developed an initial description of the electric and magnetic field structures in the outer magnetosphere region. The purpose of this paper is to examine both the losses of plasmaspheric-origin plasma into the magnetopause boundary layer and the convection of this plasma that remains trapped on closed magnetic field lines. For the LLBL electric and magnetic structures we have adopted here, the plasmaspheric plasma reaching the outer magnetosphere is diverted anti-sunward primarily along the dusk flank. These plasmas reach X = -15 R(sub E) in the LLBL approximately 3.2 hours after the initial enhancement of convection and continues to populate the LLBL for 12 hours as the convection electric field diminishes.

  16. Convection of Plasmaspheric Plasma into the Outer Magnetosphere and Boundary Layer Region: Initial Results

    NASA Technical Reports Server (NTRS)

    Ober, Daniel M.; Horwitz, J. L.

    1998-01-01

    We present initial results on the modeling of the circulation of plasmaspheric-origin plasma into the outer magnetosphere and low-latitude boundary layer (LLBL), using a dynamic global core plasma model (DGCPM). The DGCPM includes the influences of spatially and temporally varying convection and refilling processes to calculate the equatorial core plasma density distribution throughout the magnetosphere. We have developed an initial description of the electric and magnetic field structures in the outer magnetosphere region. The purpose of this paper is to examine both the losses of plasmaspheric-origin plasma into the magnetopause boundary layer and the convection of this plasma that remains trapped on closed magnetic field lines. For the LLBL electric and magnetic structures we have adopted here, the plasmaspheric plasma reaching the outer magnetosphere is diverted anti-sunward primarily along the dusk flank. These plasmas reach X= -15 R(sub E) in the LLBL approximately 3.2 hours after the initial enhancement of convection and continues to populate the LLBL for 12 hours as the convection electric field diminishes.

  17. Magnetosphere-Ionosphere Coupling at Subauroral Latitudes (Invited)

    NASA Astrophysics Data System (ADS)

    Sazykin, S.; Spiro, R. W.; Wolf, R. A.; Song, Y.; Toffoletto, F.

    2010-12-01

    On the night side of the inner magnetosphere and the conjugate ionosphere, there is a region where boundaries of several plasma populations of different origins and energy regimes (the plasmapause, the equatorward edge of the auroral oval, and the inner edge of the ring current) approximately coincide or overlap. This region is highly complex and dynamic. The magnetospheric hot plasmas and ionospheric-plasmaspheric cold populations are coupled through convection electric fields and auroral particle precipitation. Both convection (electric field) patterns and plasma densities are observed to be structured during geomagnetic disturbances, with Subauroral Polarization Streams (SAPS) near the auroral oval and plasma plumes (particularly prominent in TEC maps) extending to lower latitudes and in MLT from the nightside toward the afternoon sector. In this paper, we present an initial attempt to explain the causes of the observed ionospheric storm-time plasma structuring at mid and sub-auroral latitudes through self-consistent simulations using the Rice Convection Model. Specifically, we model the structure and longitudinal/UT dependence of SAPS structures in the duskside ionosphere, and how they may be related to meridional electron density transport postulated to be responsible for large storm-time TEC structuring in the afternoon-to-dusk MLT sector.

  18. Kinetic model of auroral plasma formation by magnetospheric convection and injection. I - Electrons

    NASA Astrophysics Data System (ADS)

    Chiu, Y. T.; Kishi, A. M.

    1984-07-01

    It is shown that Green's function solutions to the collisionless time-dependent Boltzmann equation can be economically used to construct a time-dependent model of auroral plasma formation by global time-dependent convection electric fields in dipolar magnetic geometry. It is shown that recently observed features, such as formation of field-aligned distributions, formation of injection fronts and formation of inverse dispersion signatures, can be accounted for in a global time-dependent convection model. This paper also sets forth the theoretical and presentation framework for subsequent data analytic studies of convected electron and ion distribution functions.

  19. Energetic O+ and H+ Ions in the Plasma Sheet: Implications for the Transport of Ionospheric Ions

    NASA Technical Reports Server (NTRS)

    Ohtani, S.; Nose, M.; Christon, S. P.; Lui, A. T.

    2011-01-01

    The present study statistically examines the characteristics of energetic ions in the plasma sheet using the Geotail/Energetic Particle and Ion Composition data. An emphasis is placed on the O+ ions, and the characteristics of the H+ ions are used as references. The following is a summary of the results. (1) The average O+ energy is lower during solar maximum and higher during solar minimum. A similar tendency is also found for the average H+ energy, but only for geomagnetically active times; (2) The O+ -to -H+ ratios of number and energy densities are several times higher during solar maximum than during solar minimum; (3) The average H+ and O+ energies and the O+ -to -H+ ratios of number and energy densities all increase with geomagnetic activity. The differences among different solar phases not only persist but also increase with increasing geomagnetic activity; (4) Whereas the average H+ energy increases toward Earth, the average O+ energy decreases toward Earth. The average energy increases toward dusk for both the H+ and O+ ions; (5) The O+ -to -H+ ratios of number and energy densities increase toward Earth during all solar phases, but most clearly during solar maximum. These results suggest that the solar illumination enhances the ionospheric outflow more effectively with increasing geomagnetic activity and that a significant portion of the O+ ions is transported directly from the ionosphere to the near ]Earth region rather than through the distant tail.

  20. Enhanced nonlinear interaction of powerful electromagnetic waves with ionospheric plasma near the second electron gyroharmonic

    SciTech Connect

    Istomin, Ya. N.; Leyser, T. B.

    2013-05-15

    Plasma experiments in which a powerful electromagnetic pump wave is transmitted into the ionosphere from the ground give access to a rich range of phenomena, including gyroharmonic effects when the pump frequency is near an harmonic of the ionospheric electron gyrofrequency. For pump frequencies close to the second gyroharmonic, experiments show a strong enhancement, as observed in radar scatter from pump-induced geomagnetic field-aligned density striations and optical emissions. This is in contrast to the case at the third harmonic and higher at which most of the effects are instead suppressed. We show theoretically that electrostatic oscillations can be localized in density inhomogeneities associated with small scale striations. The localized field is a mixture of the electron Bernstein and upper hybrid modes when the pump frequency is near the second gyroharmonic. The coupling of the modes is enabled by a symmetry feature of the linear electron Bernstein and upper hybrid dispersion properties that occur only near the second gyroharmonic. Electron acceleration inside the density inhomogeneities by localized azimuthal electrostatic oscillations is more efficient near the second gyroharmonic than at higher frequencies, consistent with the observed enhancements.

  1. Mid- and low-latitude prompt-penetration ionospheric zonal plasma drifts

    NASA Astrophysics Data System (ADS)

    Fejer, Bela G.; Scherliess, Ludger

    We have used ion drift observations from the DE-2 satellite to determine the latitudinal variation and the temporal evolution of mid- and low-latitude prompt penetration zonal plasma drifts driven by magnetospheric electric fields. Our results indicate that sudden increases in convection lead to predominantly westward perturbation drifts which decrease equartorwards and have largest amplitudes in the dusk-midnight sector. The diurnal perturbation drift patterns shift to later local times with increasing storm time and decay to new quasi-equilibrium values in about 2 hours, as the ring current readjusts to the new polar cap potential. The daily and latitudinal variations and temporal evolution of the DE-2 prompt penetration drifts are generally in good agreement with predictions from the Rice Convection Model, although the experimental results show larger amplitudes and longer shielding time constants.

  2. Spatial Structure of Large-Scale Plasma Density Perturbations HF-Induced in the Ionospheric F 2 Region

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Komrakov, G. P.; Glukhov, Ya. V.; Andreeva, E. S.; Kunitsyn, V. E.; Kurbatov, G. A.

    2016-07-01

    We consider the experimental results obtained by studying the large-scale structure of the HF-disturbed ionospheric region. The experiments were performed using the SURA heating facility. The disturbed ionospheric region was sounded by signals radiated by GPS navigation satellite beacons as well as by signals of low-orbit satellites (radio tomography). The results of the experiments show that large-scale plasma density perturbations induced at altitudes higher than the F2 layer maximum can contribute significantly to the measured variations of the total electron density and can, with a certain arrangement of the reception points, be measured by the GPS sounding method.

  3. Rocket-borne particle, field, and plasma observations in the cleft region. [ionospheric sounding

    NASA Technical Reports Server (NTRS)

    Ungstrup, E.; Bahnsen, A.; Olesen, J. K.; Primdahl, F.; Spangslev, F.; Heikkila, W. J.; Klumpar, D. M.; Winningham, J. D.; Fahleson, U.; Falthammar, C.-G.

    1975-01-01

    Results are reported for comprehensive observations of magnetic and electric fields together with ambient and suprathermal plasmas above the dayside auroral oval with rocket-borne instrumentation which penetrated the cleft region. Measurements were also obtained equatorward and poleward of the cleft. Convection velocities as inferred from electric-field measurements were generally toward noon equatorward of the cleft and were antisunward over the polar cap. Observations of electron temperatures, electric fields, and low-frequency electrostatic noise provide strong evidence of a plasma instability (Farley-Buneman) in the E-layer associated with the appearance of the 'slant E condition' identified in ground-acquired ionograms. The positions of these measurements relative to that of the cleft were firmly established via the determination of the plasma environment with an electrostatic analyzer.

  4. Diodelike response of high-latitude plasma in magnetosphere-ionosphere coupling in the presence of field-aligned currents

    NASA Technical Reports Server (NTRS)

    Mitchell, H. G., Jr.; Ganguli, Supriya B.; Palmadesso, P. J.

    1992-01-01

    The dynamic processes in the plasma along high-latitude field lines plays an important role in ionosphere-magnetosphere coupling process. A time-dependent, large-scale simulation of these dynamics parallel to the geomagnetic field lines from the ionosphere well into the magnetosphere is created. The plasma consists of hot e(-) and H(+) of magnetospheric origin and low-energy e(-), H(+), and O(+) of ionospheric origin. Including multiple electron species, a major improvement to the model, made it possible for the first time to simulate the upward current region properly and to dynamically simulate the diodelike response of the field-line plasma to the parallel currents coupling the ionosphere and magnetosphere. It is shown that return currents flow with small resistance, while upward currents produce kilovolt-sized potential drops along the field, as concluded from satellite observations. The kilovolt potential drops are due to the effect of the converging magnetic field on the high-energy magnetospheric electrons.

  5. Plasma instabilities in the ionosphere at the crest of anomaly region

    SciTech Connect

    Sarkar, Shivalika; Tiwari, Sunita; Gwal, A. K.

    2015-07-31

    Comparison of the in situ density fluctuations measured by the DEMETER satellite with ground based GPS receiver measurements at the equatorial anomaly station Bhopal [geographic coordinates (23.2°N, 77.6°E); geomagnetic coordinates (14.29° N, 151.12°E)] for the low solar activity year, 2005, are presented in this paper. The Langmuir Probe experiment and Plasma Analyzer onboard DEMETER measure the electron and ion densities respectively. It is interesting to note that in situ density fluctuations observed on magnetic flux tubes that pass over Bhopal can be used as indicator of ionospheric scintillations at that site. Many cases of density fluctuations and associated scintillations have been observed during descending low solar activity period.

  6. Ionospheric plasma Turbulence detection in the VLF data observed by DEMETER Satellite

    NASA Astrophysics Data System (ADS)

    Sondhiya, Deepak Kumar; Gwal, Ashok Kumar; Kumar, Sushil

    2016-07-01

    The electromagnetic wave data in the Very Low Frequency (VLF) range detected by DEMETER satellite has been analyzed, with special attention to the variation in spectral characteristics and non-linear effects, using the statistical and wavelet based techniques.The enhancement in statistical parameters shows the coherent structure and intermittent phenomenon which is the signature of turbulence. The characteristics features of VLF disturbances have further been studied using the wavelet and bispectral analysis tools which provide useful information on the plasma turbulence.A more interesting result emerges when the low-frequency turbulence emissions produce turbulence in VLF range. Finally, the relevance of the various turbulence mechanisms and their importance in ionospheric turbulence is discussed. Keywords:DEMETER, Earthquake, Phenomena of Intermittence, Coherent Structure.

  7. Numerical Modeling of High Frequency Electromagnetic Wave Propagation through Ionospheric Plasma with Randomly Distributed Flute Vortices

    NASA Astrophysics Data System (ADS)

    Caplinger, J.; Sotnikov, V. I.; Wallerstein, A. J.

    2014-12-01

    A three dimensional numerical ray-tracing algorithm based on a Hamilton-Jacobi geometric optics approximation is used to analyze propagation of high frequency (HF) electromagnetic waves through a plasma with randomly distributed vortex structures having a spatial dependence in the plane perpendicular to earth's magnetic field. This spatial dependence in density is elongated and uniform along the magnetic field lines. Similar vortex structures may appear in the equatorial spread F region and in the Auroral zone of the ionosphere. The diffusion coefficient associated with wave vector deflection from a propagation path can be approximated by measuring the average deflection angle of the beam of rays. Then, the beam broadening can be described statistically using the Fokker-Planck equation. Visualizations of the ray propagation through generated density structures along with estimated and analytically calculated diffusion coefficients will be presented.

  8. Ionospheric plasma deterioration in the area of enhanced seismic activity as compared to antipodal sites far from seismicity

    NASA Astrophysics Data System (ADS)

    Gulyaeva, Tamara; Arikan, Feza; Poustovalova, Ljubov; Stanislawska, Iwona

    2016-07-01

    The early magnetogram records from two nearly antipodal sites at Greenwich and Melbourne corresponding to the activity level at the invariant magnetic latitude of 50 deg give a long series of geomagnetic aa indices since 1868. The aa index derived from magnetic perturbation values at only two observatories (as distinct from the planetary ap index) experiences larger extreme values if either input site is well situated to the overhead ionospheric and/or field aligned current systems producing the magnetic storm effects. Analysis of the earthquakes catalogues since 1914 has shown the area of the peak global earthquake occurrence in the Pacific Ocean southwards from the magnetic equator, and, in particular, at Australia. In the present study the ionospheric critical frequency, foF2, is analyzed from the ionosonde measurements at the nearby observatories, Canberra and Slough (Chilton), and Moscow (control site) since 1944 to 2015. The daily-hourly-annual percentage occurrence of positive ionospheric W index (pW+) and negative index (pW-) is determined. It is found that the ionospheric plasma depletion pW- of the instant foF2 as compared to the monthly median is well correlated to the aa index at all three sites but the positive storm signatures show drastic difference at Canberra (no correlation of pW+ with aa index) as compared to two other sites where the high correlation is found of the ionospheric plasma density enhancement with the geomagnetic activity. A possible suppression of the enhanced ionospheric variability over the region of intense seismicity is discussed in the paper. This study is supported by TUBITAK EEEAG 115E915.

  9. Chirped dissipative ion-cyclotron solitons in the Earth's low-altitude ionospheric plasma with two ion species

    SciTech Connect

    Kovaleva, I. Kh.

    2013-03-15

    Conditions for the excitation of small-scale nonlinear ion-cyclotron gradient-drift dissipative structures in cold ionospheric plasma are considered. The solution for the wave electric field in this structure in the form of a chirped soliton satisfying the equation of the Ginzburg-Landau type is derived in the electrostatic approach. The dissipative structure as a whole represents the chirped soliton accompanied by the comoving quasineutral plasma hump. The possibility of the excitation of two modes of this type (the high- and low-frequency ones) in plasma containing light and heavy ion impurities is considered. The role of electromagnetic corrections and the possible contribution introduced by these structures to the transport processes in the ionosphere are discussed.

  10. Cold streams of ionospheric oxygen in the plasma sheet during the CDAW-6 event of March 22, 1979

    NASA Technical Reports Server (NTRS)

    Orsini, S.; Amata, E.; Candidi, M.; Balsiger, H.; Stokholm, M.; Huang, C. Y.; Lennartsson, W.; Lindqvist, P. A.

    1983-01-01

    During magnetospheric substorm events, the plasma and ion composition experiments in the ISEE-1 and 2 satellites detected cold ionospheric O+ streams, moving tailwards in the near Earth magnetotail. Flow is parallel to the magnetic field lines, with drift velocity in agreement with the electric field topology obtained by mapping the model ionospheric field along the magnetic field lines. Fluctuations of the flow velocity of the streams can be related to magnetotail movements. Oscillations of the flow direction and speed with periods ranging from 5 to 10 min that suggest the presence of waves are observed. The streams are observed at all distances between 15 and 6 Re from the Earth. When averaged over 360 deg, the streams show up as a low energy peak, superimposed on the distribution of isotropic plasma sheet ions. This double-peak structure of the energy spectrum seems typical of the disturbed plasma sheet.

  11. Electron velocity distributions and plasma waves associated with the injection of an electron beam into the ionosphere

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Paterson, W. R.; Kurth, W. S.; Ashour-Abdalla, M.; Schriver, D.

    1989-01-01

    An electron beam was injected into earth's ionosphere on August 1, 1985, during the flight of the Space Shuttle Challenger as part of the objectives of the Spacelab 2 mission. In the wake of the Space Shuttle a magnetically aligned sheet of electrons returning from the direction of propagation of the beam was detected with the free-flying Plasma Diagnostics Package. The thickness of this sheet of returning electrons was about 20 m. Large intensifications of broadband electrostatic noise were also observed within this sheet of electrons. A numerical simulation of the interaction of the electron beam with the ambient ionospheric plasmas is employed to show that the electron beam excites electron plasma oscillations and that it is possible for the ion acoustic instability to provide a returning flux of hot electrons by means of quasi-linear diffusion.

  12. Thin filament simulations for Earth's plasma sheet: Tests of validity of the quasi-static convection approximation

    NASA Astrophysics Data System (ADS)

    Wolf, R. A.; Chen, C. X.; Toffoletto, F. R.

    2012-02-01

    The main goal of this paper is to estimate the errors involved in applying a quasi-static convection model such as the Rice Convection Model (RCM) or its equilibrium version (RCM-E), which neglect inertial currents, to treat the injection of fresh particles into the inner magnetosphere in a substorm expansion phase. The approach is based on the idea that the dipolarization process involves earthward motion of a bubble that consists of flux tubes that have lower values of the entropy parameter than the surrounding medium. Our tests center on comparing MHD simulations with RCM- and RCM-E-like quasi-static approximations, for cases where the bubble is considered to be a thin ideal-MHD filament. Those quasi-static solutions miss the interchange oscillations that are often a feature of the MHD results. RCM and, to a lesser extent, RCM-E calculations tend to overestimate the westward electric field at the ionospheric footprint of the bubble and underestimate its duration. However, both get the time integral of the E × B drift velocity right as well as the net energization of the particles in the filament. The quasi-static approximation is most accurate if its computed value of the braking time of the bubble's earthward motion is long compared to the period of the relevant interchange oscillation. Comparison of MHD filament simulations of interchange instability with corresponding RCM calculations suggests a similar validity criterion. For plasma sheet conditions, the quasi-static approximation is typically best if the background medium has low β, worst if it consists of highly stretched field lines.

  13. Observations of solar-wind-driven progression of interplanetary magnetic field B{sub Y}-related dayside ionospheric disturbances

    SciTech Connect

    Stauning, P.; Friis-Christensen, E.; Clauer, C.R.

    1995-05-01

    Observations from August 2, and 3, 1991, of poleward progressing, dayside convection disturbances accompanied by geomagnetic perturbations and ionospheric radio wave absorption have been analyzed and compared to variations in the solar wind parameters as observed from the IMP 8 satellite. The convection disturbances appear to start at dayside cusp latitudes from where they progress antisunward to high latitudes. The reported observations have enabled calculations of the progression directions and velocities and precise estimates of the delays between solar wind variations as measured by the IMP 8 satellite and ionospheric convection changes as observed from an array of polar magnetic observatories. The progressing ionospheric disturbance events occur during intervals of southward interplanetary magnetic fields (negative interplanetary magnetic field (IMF) B{sub Z} component); they are found to be closely related to variations of the east-west component B{sub Y} of the IMF. The close coupling between the solar wind and the polar ionosphere(s) is explained in an open magnetospheric model in which the geomagnetic field extending from a localized region of the dayside polar cap merges with the southward interplanetary field. Variations in the IMF B{sub Y} component are reproduced in corresponding modulations of the east-west component of the plasma flow at the ionospheric foot points of the connecting `open` field lines. The perturbations of the plasma flow persist while the open field lines are convected with the ionospheric plasma across part of the dayside polar cap. The observed geomagnetic perturbations result from the combined effects of field-aligned currents and horizontal ionospheric currents, notably the convection-related Hall currents. The associated radio wave absorption events are explained as the result of E region electron heating by the horizontal electric fields associated with the convection enhancements. 48 refs., 16 figs., 3 tabs.

  14. Effect of the Crustal Magnetic Field on the Day-to-night Plasma Transport in the Martian Nightside Ionosphere

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Cui, J.

    2015-12-01

    Day-to-night plasma transport and electron precipitation from the solar wind (SW) are two most likely sources for the Martian nightside ionosphere. Although Mars does not have a large-scale intrinsic magnetic field, the existence of the crustal magnetic field and the induced field associated with the SW/Mars interaction can affect the morphology and ion-dynamics of the Martian ionosphere considerably. As revealed from the magnetometer/electron reflectometer (MAG/ER), the most intense crustal magnetic fields at Mars are located in the Terra Sirenum region. Mini-magnetospheres can be formed by the crustal magnetic anomalies, which can shield the Martian ionosphere from the upstream solar wind flow. Strong horizontal magnetic field may favor the day-to-night plasma transport and hinder the electron precipitation and the vertical plasma diffusion. In the cusp-like regions where the magnetic field line is nearly vertical, the connection with interplanetary magnetic field can permit the precipitation of the SW and the energetic particles.Here, we use the MARSIS subsurface total electron content (TEC) data to study the role of day-to-night plasma transport in the Martian nightside ionosphere. As an extended work of Cui et al. (2015), we will study the effect of different crustal magnetic components on the transport process in the Time in Darkness (TD) domain. The Bx component points to the local north, By points to the local east, and Bz points to the nadir. It is supposed that eastward By term will enhance the day-to-night plasma transport, and vice verse for the westward By term. Constraining the observations in the strong crustal magnetic region of the southern hemisphere, we find that TEC generally maintains a higher value for By > 100 nT compared with By < -100 nT as the ionosphere is turning into the night. The opposite is found for the Bz component, and it may indicate that large vertical B-field can make the plasma diffuse up or down according to the direction of

  15. Mechanisms of Ionospheric Mass Escape

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Khazanov, G. V.

    2010-01-01

    The dependence of ionospheric O+ escape flux on electromagnetic energy flux and electron precipitation into the ionosphere is derived for a hypothetical ambipolar pick-up process, powered the relative motion of plasmas and neutral upper atmosphere, and by electron precipitation, at heights where the ions are magnetized but influenced by photo-ionization, collisions with gas atoms, ambipolar and centrifugal acceleration. Ion pick-up by the convection electric field produces "ring-beam" or toroidal velocity distributions, as inferred from direct plasma measurements, from observations of the associated waves, and from the spectra of incoherent radar echoes. Ring-beams are unstable to plasma wave growth, resulting in rapid relaxation via transverse velocity diffusion, into transversely accelerated ion populations. Ion escape is substantially facilitated by the ambipolar potential, but is only weakly affected by centrifugal acceleration. If, as cited simulations suggest, ion ring beams relax into non-thermal velocity distributions with characteristic speed equal to the local ion-neutral flow speed, a generalized "Jeans escape" calculation shows that the escape flux of ionospheric O+ increases with Poynting flux and with precipitating electron density in rough agreement with observations.

  16. Convection and overshielding electric fields in the global ionosphere as observed with magnetometers and SuperDARN during the geomagnetic storm on 14-15 December 2006

    NASA Astrophysics Data System (ADS)

    Kikuchi, T.; Ebihara, Y.; Hashimoto, K. K.; Kataoka, R.; Hori, T.; Watari, S.; Nishitani, N.

    2008-12-01

    The convection electric field penetrates to the equatorial ionosphere with no significant shielding effects during the DP2 fluctuation event of period of 30 - 60 min (Nishida, 1968) and during the storm main phase continuing over several hours (Huang et al., 2007). On the other hand, shielding becomes effective during the substorm growth phase (Somajajulu et al., 1987; Kikuchi et al., 2000) and even during storm main phase (Kikuchi et al., 2008). The well-developed shielding electric field results in an overshielding at the beginning of the recovery phase of storm/substorms (Kikuchi et al., 2003, 2008). Thus, the electric field manifests complex features at mid-equatorial latitudes, which is not determined only by the solar wind electric field but strongly controlled by magnetospheric processes such as the ring current. To reveal comparative roles of the convection and overshielding electric fields and in what condition the overshielding occurs at mid-equatorial latitudes, we analyzed the geomagnetic storm on 14-15 December, 2006, characterized by the quasi-periodic DP2 fluctuation of 30 min period at the beginning of the storm. We used magnetometer data from mid- equatorial latitudes to detect magnetic signatures due to the electric field originating in the magnetosphere, and used the SuperDARN data to identify electric fields associated with the solar wind dynamo (Region-1 FAC) and the ring current (R2 FAC). We further calculated an electric potential pattern caused by the R1 and R2 FACs with the comprehensive ring current model (CRCM) to better understand the SuperDARN convection pattern. First we show that the DP2 fluctuation was caused by alternating eastward (e-EJ) and westward currents (w-EJ) in the equatorial ionosphere, which were caused by the southward and northward IMF, respectively. We further show that the e-EJ was associated with the large-scale two-cell convection vortices, while the w-EJ accompanied a reverse flow equatorward of the two

  17. Spatial distribution of plasma wave activity in the nightside ionosphere of Venus

    NASA Technical Reports Server (NTRS)

    Ho, C.-M.; Strangeway, R. J.; Russell, C. T.

    1994-01-01

    In this study we use 14 years of Pioneer Venus Orbiter Electric Field Detector (OEFD) data to define the characteristics of (VLF) burst activity in the nightside ionosphere of Venus. Our statistical results show that there are essentially four types of VLF signals. The first type of signal is only observed in the 100 Hz channel and not in any of the higher frequency channels (730 Hz, 5.4 kHz or 30 kHz). Occurrence of these waves is controlled by the magnetic field with a weaker dependence on electron density. The occurrence of these waves is controlled by the magnetic field with a weaker dependence on electron density. The occurrence rate decreases with increasing altitude to a height of 600 km. For higher altitudes beyond 600 km the occurrence rate remains roughly constant. The statistics of these signals are what one would expect for whistler mode waves from a subionospheric source. The second type of signal is broadline wave activity appearing below 300 km in the low altitude ionosphere. These signals often occur in all four channels of the OEFD. These signals are also thought to come from a subionospheric source. The third type of signal appearing near the edge of the planetary optical shadow. They are probably ion acoustic waves generated by a current driven instability associated with plasma clouds in the wake. The fourth type of signal is a narrow band wave. It occurs in either of the two high frequency channels in the high altitude tail region, and is attributed to locally generated Langmuir waves. In addition, we also observe spacecraft interference noise in both the 100 and 730 Hz channels. These signals mainly occur near the edge of the planetary optical shadow and have an inbound and outbound asymmetry in activity.

  18. Moving of the High-Speed Plasma jet Through the Ionosphere of the Different Density: Optical and Radiation Effects

    NASA Astrophysics Data System (ADS)

    Zetzer, J. I.; Erlandson, R. E.; Gavrilov, B. G.; Kiselev, Y. N.; Lynch, K. A.; Meng, C. I.; Pfaff, R. F.; Poklad, Y. V.; Rybakov, V. A.; Stenbaek-Nielsen, H.

    2003-12-01

    The investigation of the high-speed plasma jet dynamics in the geomagnetic field has important implications to the basic magnetospheric and ionospheric physics and to the applied problems. The new results of the active geophysical rocket experiment (AGRE) "North Star" (1999) are represented. The high-speed plasma jet was injected on the altitudes 360 and 280 km perpendicular to the geomagnetic field. During first injection plasma jet was injected in the artificial air cloud with the density ~ 10-12 g/cm3, during second one - in the free space with the density ~ 10-15 g/cm3. The design and characteristics of the plasma jet generator, the radiation dynamics of the plasma cloud and dynamics of the charged particles takes place during of the process of the interaction of the plasma jet with environment are discussed.

  19. Plasma heating, plasma flow and wave production around an electron beam injected into the ionosphere

    NASA Technical Reports Server (NTRS)

    Winckler, J. R.; Erickson, K. N.

    1986-01-01

    A brief historical summary of the Minnesota ECHO series and other relevant electron beam experiments is given. The primary purpose of the ECHO experiments is the use of conjugate echoes as probes of the magnetosphere, but beam-plasma and wave studies were also made. The measurement of quasi-dc electric fields and ion streaming during the ECHO 6 experiment has given a pattern for the plasma flow in the hot plasma region extending to 60m radius about the ECHO 6 electron beam. The sheath and potential well caused by ion orbits is discussed with the aid of a model which fits the observations. ELF wave production in the plasma sheath around the beam is briefly discussed. The new ECHO 7 mission to be launched from the Poker Flat range in November 1987 is described.

  20. Effects of ionizing energetic electrons and plasma transport in the ionosphere during the initial phase of the December 2006 magnetic storm

    NASA Astrophysics Data System (ADS)

    Suvorova, A. V.; Huang, C.-M.; Dmitriev, A. V.; Kunitsyn, V. E.; Andreeva, E. S.; Nesterov, I. A.; Klimenko, M. V.; Klimenko, V. V.; Tumanova, Yu. S.

    2016-06-01

    The initial phase of a major geomagnetic storm on 14 December 2006 was selected in order to investigate the ionizing effect of energetic electrons in the ionosphere. The global network of GPS receivers was used to analyze the total electron content (TEC). A strong positive ionospheric storm of ~20 TEC units (TECU) with ~6 h duration was observed on the dayside during the interval of northward interplanetary magnetic field. At the same time, the NOAA/POES satellites observed long-lasting intense fluxes of >30 keV electrons in the topside ionosphere at middle and low latitudes, including a near-equatorial forbidden zone outside of the South Atlantic Anomaly (SAA). We found that the TEC increases overlapped well with the enhancements of energetic electrons. Modeling of the ionospheric response by using a Global Self-consistent Model of the Thermosphere, Ionosphere, and Protonosphere, based on the standard mechanisms of plasma transport, could only partially explain the ionospheric response and was unable to predict the long-duration increase of TEC. For the energetic electrons, we estimated the ionizing effect of ~45 TECU and ~23 TECU in the topside ionosphere, respectively, inside and outside of SAA. The ionizing effect contributed from 50% to 100% of TEC increases and provided the long duration and wide latitudinal extension of the positive ionospheric storm. This finding is a very important argument in supporting significant ionizing effect of energetic electrons in the storm time ionosphere both at middle and low latitudes.

  1. Investigating Solar Wind-Magnetosphere-Ionosphere Coupling with SuperDARN and AMPERE

    NASA Astrophysics Data System (ADS)

    Milan, S. E.; Coxon, J.; Imber, S. M.; Clausen, L.; Korth, H.; Anderson, B. J.

    2013-12-01

    The dynamics of the Earth's plasma environment are driven by coupling between the solar wind, with its embedded interplanetary magnetic field, and the magnetosphere through magnetic reconnection occurring at the magnetopause. Terrestrial magnetic field lines which are connected to interplanetary space in this way are subsequently released by magnetic reconnection occurring in the magnetotail. These two processes lead to increases and decreases in the proportion of the terrestrial flux that is open, as observed in changes in the latitude of the auroral zones. A circulation of plasma and magnetic flux is effected, the Dungey cycle, with a sympathetic plasma convection signature in the ionosphere. In this talk we review recent advances of our understanding of the coupling process, provided by measurements of ionospheric convection with the Super Dual Auroral Radar Network (SuperDARN) and the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) which measures the coupling currents that transfer stress from the magnetosphere into the ionosphere.

  2. Equatorial transport of Saturn's ionosphere as driven by a dust-ring current system

    SciTech Connect

    Ip, W.; Mendis, D.A.

    1983-03-01

    The diurnal modulation of the dust ring current of Saturn's D-ring causes field-aligned Birkeland currents ot flow near the dawn and dusk terminators and close across the mid-latitude ionosphere. One consequence of this current system is the establishment of a global convection pattern in the equatorial outer ionosphere. Outward motion of the dayside ionosheric plasma as well as the corresponding absorption effect of the inner ring system might be one physical cause of the depletion of the ionospheric content of Saturn.

  3. Drift zonal plasma ionospheric in the Brazilian sector during a period of extreme low solar activity

    NASA Astrophysics Data System (ADS)

    Abalde Guede, Jose Ricardo; Tardelli-Coelho, Flavia Elaine

    2016-07-01

    The zonal drift velocities of the ionospheric plasma irregularities of large scale were analyzed; these irregularities were observed using optical emission techniques OI 630.0 nm obtained by photometers imagers installed in two locations on the campus of Urbanova UNIVAP in São José dos Campos - SP designated SJC and Campus ULBRA in Palmas - TO cited as PAL. Data were collected from five years, from 2006 to 2010, low solar activity period. Of the total of 337 nights in SJC and 329 nights in PAL analyzed were selected a total of 18 nights of significant plasma bubble occurrences, 9 nights in SJC and 9 nights in PAL, and studied under two conditions: considering fixed altitude of 280 km OI emission layer of 630.0 nm and calculating the height of this variable layer over each night analyzed. To find these varying altitudes along each night we were assisted with the analysis of CADI digital ionosonde data operating in conjunction with the imaging photometer in its observatory. The radio data available in digisonde allowed to do the analysis on 12 variables altitudes of 18 nights studied for fixed altitude; this occurred because of scattering present in ionograms for those nights and times, due to the presence of plasma bubbles in the study through the of the observatory zenith. Quantitative analysis determined the drift velocity zone for each of the analyzed bubbles 18 nights during the given fixed height and 12 nights evaluating varying altitudes along each night. The means were obtained nights analyzed in each observatory for both methods; SJC in the average velocities is derived from the plasma zone 9 nights bubbles analyzed in the method is fixed altitude 84 ± 18 m / s in the case of PAL the average velocities found is 87 ± 12 m / s. In the other case with variable altitude emission to SJC 8 nights analyzed, we reached a mean value of 87 ± 12 m / s, and for PAL, 4 of 9 nights initially selected, the average speed of the zonal drift plasma bubbles were found 85

  4. Convective dust clouds driven by thermal creep in a complex plasma.

    PubMed

    Mitic, S; Sütterlin, R; Höfner, A V Ivlev H; Thoma, M H; Zhdanov, S; Morfill, G E

    2008-12-01

    Steady-state clouds of microparticles were observed, levitating in a low-frequency glow discharge generated in an elongated vertical glass tube. A heated ring was attached to the tube wall outside, so that the particles, exhibiting a global convective motion, were confined vertically in the region above the location of the heater. It is shown that the particle vortices were induced by the convection of neutral gas, and the mechanism responsible for the gas convection was the thermal creep along the inhomogeneously heated tube walls. The phenomenon of thermal creep, which commonly occurs in rarefied gases under the presence of thermal gradients, should generally play a substantial role in experiments with complex plasmas.

  5. Evidence of auroral oval TEC enhancement and simultaneous plasma patch break-off events in the Arctic and Antarctic ionosphere during the initial phase of a geomagnetic storm event at equinox, 26 September 2011

    NASA Astrophysics Data System (ADS)

    Kinrade, Joe; Mitchell, Cathryn; Paxton, Larry; Bust, Gary

    2013-04-01

    A moderate geomagnetic storm during 26-27 September 2011 instigated ionospheric TEC responses in the high latitude regions, imaged in this dual-hemispheric study using the ionospheric reconstruction tool MIDAS (Multi-Instrument Data Analysis System). This case study showcases the current capabilities of GPS inversion tomography at high latitudes, given the improvement in ground-based receiver distribution in the polar reaches during the last decade. Several interesting features of the high latitude response are highlighted. During the initial phase of the storm (Dst+ increase signature), a ring feature in the TEC was imaged around the position of the Arctic auroral oval that persisted for over an hour. Verification of the auroral oval position and incident particle precipitation was provided by the SSUSI ultra-violet imager and SSJ/4 spectrometer on-board the polar-orbiting DMSP satellites. Shortly after the ring feature dissipated, two consecutive and defined plasma patch break-off events occurred within the North American sector, with anti-sunward convection then circulating the TEC enhancements over Greenland and Iceland. Apparent during the main phase of the storm (Dst- signature), these break-off events were likely triggered by switching periods of the interplanetary magnetic field (IMF) from southward (Bz-) to northward (Bz+) under constant By+ conditions projected at the magnetopause. A coincident patch break-off event was imaged in the Antarctic in the local dawn-noon sector; this simultaneity may be attributed to the more balanced incidence angle of the IMF during equinox upon the Northern and Southern hemispheres. Finally, the ionospheric trough was identified over Scandinavia and Europe as a clear band of depletion between the storm-enhanced dayside electron density and expansion of the auroral zone during the main phase of the storm. This study demonstrates that, in combination with other instruments, GPS tomography has become a useful tool providing a

  6. On the Relative Importance of Convection and Temperature on the Behavior of the Ionosphere in North American during January 6-12, 1997

    NASA Technical Reports Server (NTRS)

    Richards, P. G.; Buonsanto, M. J.; Reinisch, B. W.; Holt, J.; Fennelly, J. A.; Scali, J. L.; Comfort, R. H.; Germany, G. A.; Spann, J.; Brittnacher, M.

    1999-01-01

    Measurements from a network of digisondes and an incoherent scatter radar In Eastern North American For January 6-12, 1997 have been compared with the Field Line Interhemispheric Plasma (FLIP) model which now includes the effects of electric field convective. With the exception of Bermuda, the model reproduces the daytime electron density very well most of the time. As is typical behavior for winter solar minimum on magnetically undisturbed nights, the measurements at Millstone Hill show high electron temperatures before midnight followed by a rapid decay, which is accompanied by a pronounced density enhancement in the early morning hours. The FLIP model reproduces the nighttime density enhancement well, provided the model is constrained to follow the topside electron temperature and the flux tube is full. Similar density enhancements are seen at Goose Bay, Wallops Island and Bermuda. However, the peak height variation and auroral images indicate the density enhancements at Goose Bay are most likely due to particle precipitation. Contrary to previously published work we find that the nighttime density variation at Millstone Hill is driven by the temperature behavior and not the other way around. Thus, in both the data and model, the overall nighttime density is lowered and the enhancement does not occur if the temperature remains high all night. Our calculations show that convections of plasma from higher magnetic latitudes does not cause the observed density maximum but it may enhance the density maximum if over-full flux tubes are convected over the station. On the other had, convection of flux tubes with high temperatures and depleted densities may prevent the density maximum from occurring. Despite the success in modeling the nighttime density enhancements, there remain two unresolved problems. First, the measured density decays much faster than the modeled density near sunset at Millstone Hill and Goose Bay though not at lower latitude stations. Second, we

  7. Estimation of Ionospheric Conductivity Based on the Measurements by Superdarn

    NASA Astrophysics Data System (ADS)

    Lee, Eun-Ah; An, Byung-Ho; Yi, Yu

    2002-06-01

    The ionosphere plays an important role in the electrodynamics of space environment. In particular, the information on the ionospheric conductivity distribution is indispensable in understanding the electrodynamics of the magnetosphere and ionosphere coupling study. To meet such a requirement, several attempts have been made to estimate the conductivity distribution over the polar ionosphere. As one of such attempts we compare the ionospheric plasma convection patterns obtained from the Super Dual Auroral Radar Network (SuperDARN), from which the electric field distribution is estimated, and the simultaneously measured ground magnetic disturbance. Specifically, the electric field measured from the Goose Bay and Stokkseyri radars and magnetic disturbance data obtained from the west coast chain of Greenland are compared. In order to estimate ionospheric conductivity distribution with these information, the overhead infinite sheet current approximation is employed. As expected, the Hall conductance, height-integrated conductivity, shows a wide enhancement along the center of the auroral electrojet. However, Pedersen conductance shows negative values over a wide portion of the auroral oval region, a physically unacceptable situation. To alleviate this problem, the effect of the field-aligned current is taken into account. As a result, the region with negative Pedersen conductance disappears significantly, suggesting that the effect of the field-aligned current should be taken into account, when one wants to estimate ionospheric conductance based on ground magnetic disturbance and electric field measurements by radars.

  8. The interaction of a magnetic cloud with the Earth - Ionospheric convection in the Northern and Southern Hemispheres for a wide range of quasi-steady interplanetary magnetic field conditions

    NASA Technical Reports Server (NTRS)

    Freeman, M. P.; Farrugia, C. J.; Burlaga, L. F.; Hairston, M. R.; Greenspan, M. E.; Ruohoniemi, J. M.; Lepping, R. P.

    1993-01-01

    Observations are presented of the ionospheric convection in cross sections of the polar cap and auroral zone as part of the study of the interaction of the Earth's magnetosphere with the magnetic cloud of January 13-15, 1988. For strongly northward IMF, the convection in the Southern Hemisphere is characterized by a two-cell convection pattern comfined to high latitudes with sunward flow over the pole. The strength of the flows is comparable to that later seen under southward IMF. Superimposed on this convection pattern there are clear dawn-dusk asymmetries associated with a one-cell convection component whose sense depends on the polarity of the magnetic cloud's large east-west magnetic field component. When the cloud's magnetic field turns southward, the convection is characterized by a two-cell pattern extending to lower latitude with antisunward flow over the pole. There is no evident interhemispheric difference in the structure and strength of the convection. Superimposed dawn-dusk asymmetries in the flow patterns are observed which are only in part attributable to the east-west component of the magnetic field.

  9. Relationship of the interplanetary electric field to the high-latitude ionospheric electric field and currents Observations and model simulation

    NASA Technical Reports Server (NTRS)

    Clauer, C. R.; Banks, P. M.

    1986-01-01

    The electrical coupling between the solar wind, magnetosphere, and ionosphere is studied. The coupling is analyzed using observations of high-latitude ion convection measured by the Sondre Stromfjord radar in Greenland and a computer simulation. The computer simulation calculates the ionospheric electric potential distribution for a given configuration of field-aligned currents and conductivity distribution. The technique for measuring F-region in velocities at high time resolution over a large range of latitudes is described. Variations in the currents on ionospheric plasma convection are examined using a model of field-aligned currents linking the solar wind with the dayside, high-latitude ionosphere. The data reveal that high-latitude ionospheric convection patterns, electric fields, and field-aligned currents are dependent on IMF orientation; it is observed that the electric field, which drives the F-region plasma curve, responds within about 14 minutes to IMF variations in the magnetopause. Comparisons of the simulated plasma convection with the ion velocity measurements reveal good correlation between the data.

  10. Studies of the auroral ionosphere with the MITHRAS

    NASA Astrophysics Data System (ADS)

    Foster, J. C.

    1986-06-01

    The extensive MITHRAS radar data set was the object of extensive analyses of the processes and characteristics of the auroral latitude ionosphere and thermosphere: (1) High-Latitude Electrodynamics: Ionospheric response to substorms at widely separated local times was investigated. (2) Ionospheric Plasma Transport: The effects of plasma convection on the formation of the midlatitude trough were studied utilizing the wide spatial field of view of the Millstone radar. (3) Convection Snapshots: Simultaneous data from spaced instruments were combined to produce snapshots of the polar and auroral convection pattern. (4) Comparisons with Models. (5) Data Bases Studies and Empirical Models: The extensive data set which resulted from the MITHRAS experimental program was incorporated into a multi-instrument, common format data base. (6) Azimuth Scan Experiments: Analysis of the complex data during MITHRAS azimuth scanning experiments resulted in the capability of mapping the convection electric field within the extended field of the radar. (7) Thermosphere and Exosphere: The diurnal variation of exospheric temperature over 30 degrees of latitude around Millstone Hill has been investigated using MITHRAS elevation scan data.

  11. Plasma convection in the nightside magnetosphere of Saturn determined from energetic ion anisotropies

    NASA Astrophysics Data System (ADS)

    Kane, M.; Mitchell, D. G.; Carbary, J. F.; Krimigis, S. M.

    2014-02-01

    The Cassini Ion and Neutral Camera measures intensities of hydrogen and oxygen ions and neutral atoms in the Saturnian magnetosphere and beyond. We use the measured intensity spectrum and anisotropy of energetic hydrogen and oxygen ions to detect, qualify, and quantify plasma convection. We find that the plasma azimuthal convection speed relative to the local rigid corotation speed decreases with radial distance, lagging the planetary rotation rate, and has no significant local time dependences. Plasma in the dusk-midnight quadrant sub-corotates at a large fraction of the rigid corotation speed, with the primary velocity being azimuthal but with a distinct radially outward component. The duskside velocities are similar to those obtained from earlier orbits in the midnight-dawn sector, in contrast to the depressed velocities measured at Jupiter using Energetic Particles Detector measurements on the Galileo spacecraft in the dusk-midnight quadrant. We find significant radial outflow in most of the nightside region. The radial component of the flow decreases with increasing local time in the midnight-dawn sector and reverses as dawn is approached. This and previous results are consistent with a plasma disk undergoing a centrifugally induced expansion as it emerges into the nightside, while maintaining partial rotation with the planet. The magnetodisk expansion continues as plasma rotates across the tail to the dawnside. We do not see evidence in the convection pattern for steady state reconnection in Saturn's magnetotail. The outermost region of the magnetodisk, having undergone expansion upon emerging from the dayside magnetopause confinement, is unlikely to recirculate back into the dayside. We conclude that plasma in the outer magnetodisk [at either planet] rotates from the dayside, expands at the dusk flank, but remains magnetically connected to the respective planet while moving across the tail until it interacts with and is entrained into the dawnside

  12. Ionosphere-thermosphere space weather issues.

    NASA Astrophysics Data System (ADS)

    Schunk, R. W.; Sojka, J. J.

    1996-10-01

    Weather disturbances in the ionosphere-thermosphere system can have a detrimental effect on both ground-based and space-based systems. Because of this impact and because this field has matured, it is now appropriate to develop specification and forecast models, with the aim of eventually predicting the occurrence, duration, and intensity of weather effects. As part of the new National Space Weather Program, the CEDAR community will focus on science issues concerning space weather, and this tutorial/review is an expanded version of a tutorial presentation given at the recent CEDAR annual meeting. The tutorial/review provides a brief discussion of weather disturbances and features, the causes of weather, and the status of weather modeling. The features and disturbances discussed include plasma patches, boundary and auroral blobs, Sun-aligned polar cap arcs, the effects of traveling convection vortices and SAID events, the lifetime of density structures, sporadic-E and intermediate layers, spread F and equatorial plasma bubbles, geomagnetic storms and substorms, traveling ionospheric disturbances (TIDs), and the effects of tides and gravity waves propagating from the lower atmosphere. The tutorial/review is only intended to provide an overview of some of the important scientific issues concerning ionospheric-thermospheric weather, with the emphasis on the ionosphere. Tutorials on thermospheric and magnetospheric weather issues are given in companion papers.

  13. Electric Field Observations of Plasma Convection, Shear, Alfven Waves, and other Phenomena Observed on Sounding Rockets in the Cusp and Boundary Layer

    NASA Technical Reports Server (NTRS)

    Pfaff, R. F.

    2009-01-01

    On December 14,2002, a NASA Black Brant X sounding rocket was launched equatorward from Ny Alesund, Spitzbergen (79 N) into the dayside cusp and subsequently cut across the open/closed field line boundary, reaching an apogee of771 km. The launch occurred during Bz negative conditions with strong By negative that was changing during the flight. SuperDarn (CUTLASS) radar and subsequent model patterns reveal a strong westward/poleward convection, indicating that the rocket traversed a rotational reversal in the afternoon merging cell. The payload returned DC electric and magnetic fields, plasma waves, energetic particle, suprathermal electron and ion, and thermal plasma data. We provide an overview of the main observations and focus on the DC electric field results, comparing the measured E x B plasma drifts in detail with the CUTLASS radar observations of plasma drifts gathered simultaneously in the same volume. The in situ DC electric fields reveal steady poleward flows within the cusp with strong shears at the interface of the closed/open field lines and within the boundary layer. We use the observations to discuss ionospheric signatures of the open/closed character of the cusp/low latitude boundary layer as a function of the IMF. The electric field and plasma density data also reveal the presence of very strong plasma irregularities with a large range of scales (10 m to 10 km) that exist within the open field line cusp region yet disappear when the payload was equatorward of the cusp on closed field lines. These intense low frequency wave observations are consistent with strong scintillations observed on the ground at Ny Alesund during the flight. We present detailed wave characteristics and discuss them in terms of Alfven waves and static irregularities that pervade the cusp region at all altitudes.

  14. Monitoring of the velocity field of the plasma motion under sounding of F ionospheric region by the probe waves

    NASA Astrophysics Data System (ADS)

    Sergeev, Evgeny; Komrakov, G. P.; Smyshlyaev, Sergey E.

    Results of investigations of the motions in F region of the ionosphere by means of the method of the space-frequency diversity reception are presented. Measurements of the vertical and horizontal plasma drift velocities have been performed over SURA facility (Russia) using of multifrequency dopler station for vertical sounding and diversity three point reception of the reflected radiosignals. Possibilities of a day (15 hours) monitoring of the drift velocity space at different altitudes were studied by using of the three fixed probe frequencies 4353 kHz, 5853 kHz and 7353 kHz. For another experimental series complex investigations of the pumped ionospheric volume were performed by its diagnostics at different frequencies with the short (¡ 200 mks) wide frequency band (˜ 500 kHz) and powerful (˜ 20 - 150 MW ERP) pulses. Data about a fine distribution structure of the vertical and horizontal plasma drift velocities in the turbulence plasma range were first obtained with a high frequency (˜ 1 kHz) and temporal (˜ 20 ms) resolution. The work was supported by RFBR grants 07-02-00464 and 06-02-17334.

  15. Current leakage for low altitude satellites - Modeling applications. [simulation of high voltage solar cell array in ionospheric plasma environment

    NASA Technical Reports Server (NTRS)

    Konradi, A.; Mccoy, J. E.; Garriott, O. K.

    1979-01-01

    To simulate the behavior of a high voltage solar cell array in the ionospheric plasma environment, the large (90 ft x 55 ft diameter) vacuum chamber was used to measure the high-voltage plasma interactions of a 3 ft x 30 ft conductive panel. The chamber was filled with Nitrogen and Argon plasma at electron densities of up to 1,000,000 per cu cm. Measurements of current flow to the plasma were made in three configurations: (a) with one end of the panel grounded, (b) with the whole panel floating while a high bias was applied between the ends of the panel, and (c) with the whole panel at high negative voltage with respect to the chamber walls. The results indicate that a simple model with a constant panel conductivity and plasma resistance can adequately describe the voltage distribution along the panel and the plasma current flow. As expected, when a high potential difference is applied to the panel ends more than 95% of the panel floats negative with respect to the plasma.

  16. Irregularities in ionospheric plasma clouds: their evolution and effect on radio communication. Technical report

    SciTech Connect

    Vesecky, J.F.; Chamberlain, J.W.; Cornwall, J.M.; Hammer, D.A.; Perkins, F.W.

    1980-09-01

    Both satellite radio communications, which travel through the Earth's ionosphere, and high frequency (HF) sky wave circuits, which use the ionosphere as a refracting medium, can be strongly affected by radio wave scintillation. High altitude nuclear explosions cause scintillation (by strongly disturbing the ionosphere) and thus severely degrade satellite radio communications over a large region. Since further atmospheric nuclear tests are banned, a thorough understanding of the physics involved in both the disturbed ionosphere and its interaction with radio waves is necessary in order to design radio communications systems which will operate satisfactorily in a nuclear environment. During the 1980 JASON Summer Study we addressed some aspects of the evolution of ionospheric irregularities following a high altitude nuclear explosion--the radio wave propagation theory being apparently well understood for the satellite link case. In particular, we have worked on irregularity evolution at late times (approx. hours) after an explosion and the impact of early time irregularity structure on late time evolution. We also raise the question of scintillation effects on HF sky wave communications.

  17. Ionospheric scintillation studies. Final report, October 1984-September 1987

    SciTech Connect

    Livingston, R.C.

    1988-05-01

    Irregular structure in ionospheric plasma density can significantly affect DoD communications and radar systems that utilize transionospheric radiowave paths. Transport and dissipation of ionospheric structure is therefore of direct relevance. Such an understanding can aid the long-term goal of developing a predictive capability for global ionospheric structure. Experimental observation of the ionosphere over the past few years has concentrated on high latitudes. This is the most-complex portion of the global ionospheric system; the auroral zone, the polar cap, and the boundary between them can all be regions of highly dynamic and structured plasma. In the polar cap, very-large-scale plasma patches and sun-aligned arcs occur, and can convect rapidly from their source regions to the entire high-latitude region. Much of what has been learned about this extended regime of irregularity structure at high latitudes has been through the application of complementary diagnostics: Optics, ionosonde, incoherent scatter radar, in-situ satellite, and scintillation measurements. These various techniques allow the observation of structure over several orders of magnitude in spatial scale. The optics, ionosonde, and radar provide an overall view of large-scale production and dynamics; the satellites diagnose the inputs to the large- and medium-scale irregularities; from the scintillation data, the strength, shape, and motion of the kilometer-scale structure can be identified.

  18. Structure of the Martian Ionosphere: MAVEN STATIC First Results

    NASA Astrophysics Data System (ADS)

    McFadden, James P.; Livi, Roberto; Luhmann, Janet; Connerney, Jack; Mitchell, David L.; Mazelle, Christian; Andersson, Laila; Jakosky, Bruce

    2015-04-01

    The Suprathermal And Thermal Ion Composition (STATIC) sensor on the MAVEN spacecraft provides the first detailed look at the Martian ionosphere and its interface to the solar wind. STATIC measures ion composition, density, temperature, and flows in the deep ionosphere (<180 km), resolving the cold O2+ dominated plasma whose temperature is often less than 0.02 eV. The nightside ionosphere has shown a remarkable amount of structure with sharp gradients in both density and composition on horizontal scale sizes of ~10 km. During deep-dip excursions to ~125 km in eclipse, STATIC observed tenuous heavy ions in with M/Q of ~55-60 and ~85-90 amu/e. STATIC has captured the transition to a warmer, mixed ionosphere between 200 and 500 km altitudes where comparable amounts of O2+, O+, and H+ are observed. STATIC also resolves more tenuous concentrations of CO2+, H2+, H3+, He+, C+, and O++ at these intermediate altitudes. In addition to measuring cold ionospheric plasma, STATIC measures the heating and acceleration of cold ions to escape velocities at the solar wind interface. Counter-streaming ion beams are observed in these heating regions, along with significant convection flows and velocity-dispersed ion signatures. Draped magnetic field capture of cold ionospheric plasma is directly observed as a loss mechanism where dense beams of ions are accelerated down the magnetotail along the current sheet. This talk will focus on the low and intermediate altitude observations by STATIC which reveal a wealth of ionospheric structure and plasma dynamics that play a role in atmospheric loss.

  19. Electric fields and electrostatic potentials in the high latitude ionosphere

    NASA Technical Reports Server (NTRS)

    Banks, P. M.; Saint Maurice, J.-P.; Heelis, R. A.; Hanson, W. B.

    1981-01-01

    Recent interpretive studies of electric field-driven ionospheric plasma convection data from the AE-C satellite are described, where the instruments employed include an ion drift meter and an ion-retarding potential analyzer. Electrostatic potential curves are derived from ion drift velocity measurements for high-latitude segments of the satellite's orbit. The potential curves are shown to be useful in determining the character of the global electrostatic potential pattern, with emphasis on the separation of convective cells. Results are given for six orbits, with attention to the mid-day auroral region.

  20. A method for determining the drift velocity of plasma depletions in the equatorial ionosphere using far-ultraviolet spacecraft observations

    NASA Astrophysics Data System (ADS)

    Park, S. H.; England, S. L.; Immel, T. J.; Frey, H. U.; Mende, S. B.

    2007-11-01

    The Far-Ultraviolet Imager (IMAGE-FUV) on board the NASA IMAGE satellite has been used to observe plasma depletions in the nightside equatorial ionosphere. Observations from periods around spacecraft apogee, during which equatorial regions are visible for several hours, have allowed the velocity of these plasma depletions to be determined. A new method for determining the velocity of these depletions using an image analysis technique, Tracking Of Airglow Depletions (TOAD), has been developed. TOAD allows the objective identification and tracking of depletions. The automation of this process has also allowed for the tracking of a greater number of depletions than previously achieved without requiring any human input, which shows that TOAD is suitable for use with large data sets and for future routine monitoring of the ionosphere from space. Furthermore, this automation allows the drift velocities of each bubble to be determined as a function of magnetic latitude, which will give us the capability of retrieving geophysically important parameters such as the electric field, which are believed to vary rapidly with magnetic latitude.

  1. Ionospheric disturbances during the magnetic storm of 15 July 2000: Role of the fountain effect and plasma bubbles for the formation of large equatorial plasma density depletions

    NASA Astrophysics Data System (ADS)

    Kil, Hyosub; Paxton, Larry J.

    2006-12-01

    We investigate the role of the fountain effect and plasma bubbles for the formation of the large equatorial plasma depletions during the geomagnetic storm of 15 July 2000. The large equatorial plasma depletions are detected in the Atlantic sector on the night of the 15th by the Defense Meteorological Satellite Program (DMSP) F15 and the first Republic of China Satellite (ROCSAT-1). The observations show discontinuous drop of the plasma density at the walls of the depletions, flat plasma density inside the depletions, and persistence or growth of the depletions over night. These properties are not consistent with the trough morphology induced by the fountain effect. The coincident ionospheric observations of DMSP F15 and ROCSAT-1 demonstrate that the large depletions are created in the longitude regions where plasma bubbles are present. The occurrence of the large depletions after sunset, elongation in the north-south direction, formation of steep walls, and colocation with plasma bubbles at lower altitudes or earlier times suggest that the large depletions are closely associated with plasma bubbles.

  2. Numerical modeling of the large-scale neutral and plasma responses to the body forces created by the dissipation of gravity waves from 6 h of deep convection in Brazil

    NASA Astrophysics Data System (ADS)

    Vadas, S. L.; Liu, H.-L.

    2013-05-01

    We study the response of the thermosphere and ionosphere to gravity waves (GWs) excited by 6 h of deep convection in Brazil on the evening of 01 October 2005 via the use of convective plume, ray trace, and global models. We find that primary GWs excited by convection having horizontal wavelengths of λH˜70-300 km, periods of 10-60 min, and phase speeds of cH˜50-225 m/s propagate well into the thermosphere. Their density perturbations are ρ'/ρ300 km. The dissipation of these GWs creates spatially and temporally localized body forces with amplitudes of 0.2- 1.0 m/s2at z˜120-230 km. These forces generate two counter-rotating circulation cells with horizontal velocities of 50-350 m/s. They also excite secondary GWs; those resolved by our global model have λH˜4000-5000 km and cH˜500-600 m/s. These secondary GWs propagate globally and have ρ'/ρplasma perturbations of foF2'˜0.2-1.0 MHz, TEC'˜0.4- 1.5 TECU (total electron content unit, 1TECU =1016 elm-2), and hmF2'˜5-50 km. The large-scale traveling ionospheric disturbances (LSTIDs) induced by the secondary GWs have amplitudes of foF2'˜0.2-0.5 MHz, TEC'˜0.2- 0.6 TECU, and hmF2'˜5-10 km. In a companion paper, we discuss changes to the prereversal enhancement and plasma drift from these forces.

  3. High-order stimulated ionospheric diffuse plasma resonances: Significance for magnetospheric emissions

    SciTech Connect

    Benson, R.F. ); Osherovich, V.A. )

    1992-12-01

    The sequence nature of the diffuse ionospheric resonances D[sub n] stimulated by topside sounders was discovered by Oya (1970) with n ranging from 1 to 4. Osherovich (1987) organized these observations using his earlier theory which predicted a nonequidistant spectrum with frequencies proportional to n[sup [1/2

  4. The access of dayside ionospheric O + ions to the plasma sheet during the september 24-25, 1998 magnetic storm

    NASA Astrophysics Data System (ADS)

    Peroomian, Vahé; El-Alaoui, Mostafa; Abdalla, Maha Ashour; Zelenyi, Lev M.

    2006-01-01

    We have investigated the population of the magnetosphere by ionospheric O + ions from the dayside during the first 8 h of the September 24-25, 1998 magnetic storm by tracing ion trajectories from the ionosphere in time-dependent electric and magnetic fields obtained from a three-dimensional global magnetohydrodynamic (MHD) simulation of the magnetosphere during this storm event. The MHD simulation used WIND data upstream of Earth as input for this storm that began at 2345 UT on September 24, 1998, when a magnetic cloud impacted Earth's magnetosphere. Ions were launched from both hemispheres on the dayside, in a region extending from 11 to 13 MLT and from 70° to 85° invariant latitude at five minute intervals, beginning 2 h before storm onset and extending to 8 h after the storm commenced. Ions were launched with energies that reflected the effects of ion energization along field lines during this event (e.g. [Cladis, J.B., Collin, H.L., Lennartsson, O.W., Moore, T.E., Peterson, W.K., Russell, C.T., 2000. Observations of centrifugal acceleration during compression of magnetosphere. Geophys. Res. Lett. 27, 915.]), as these effects were not a priori included in the MHD simulation of the event. The ion launch rate was dynamically normalized to observations by using the [Pollock Jr., C.J., Chappell, C.R., Gurnett, D.A., 1990. A survey of upwelling ion event characteristics. J. Geophys. Res. 95, 18-969.] and [Moore, T.E., Peterson, W.K., Russell, C.T., Chandler, M.O., Collier, M.R., Collin, H.L., Craven, P.D., Fitzenreiner, R., Giles, B.L., Pollock, C.J., 1999. Ionospheric mass ejection in response to a CME. Geophys. Res. Lett. 26, 2339.] relationship between the standard deviation of solar wind dynamic pressure and dayside O + outflow. We found that ionospheric O + ions had access to the plasma sheet beyond a radial distance of 10 RE before the storm, but gained access to the near-Earth region and partial ring current soon after the sudden commencement. In addition

  5. Drifts, boundary conditions and plasma convection on open magnetic field lines

    SciTech Connect

    Cohen, R. H.

    1998-11-20

    In a number of plasmas of practical interest, including the scrape-off layer of a tokamak with a divertor or toroidal limiter, some gas discharge devices, and in the vicinity of spacecraft, magnetic field lines intersect bounding surfaces at shallow angles. Under these circumstances a number of interesting and important effects arise. Drifts can compete with parallel flows in establishing the boundary conditions for plasma mass-flow and current (sheath current-voltage characteristics). We derive the mass-flow constraints including both poloidal and radial drifts, review the current boundary conditions, and survey the consequences, including along-field density and heat-flux asymmetries, convection created by a wavy surface, generation of electric fields and surface currents associated with shadows from surface structures, and modification of instability growth.

  6. Magnetospheric Sawtooth Oscillations Induced by Ionospheric Outflow

    NASA Astrophysics Data System (ADS)

    Brambles, O. J.; Lotko, W.; Zhang, B.; Lyon, J.; Wiltberger, M. J.

    2010-12-01

    This paper aims to address why sawtooth oscillations occur and what factors affect their periodicity. We use a multifluid version of the LFM global simulation model, driven by a steady solar wind to examine the effects of ion outflow on convection in the magnetosphere. In the simulation model, the properties of cusp and auroral region O+ outflow are causally regulated by electron precipitation and electromagnetic power flowing into the ionosphere. It is found that when ion outflow is included in the simulation, the solar wind-magnetosphere-ionosphere interaction can generate periodic substorms which appear as sawtooth-like oscillations in the geostationary magnetic field. The ion outflow enhances plasma pressure in the inner magnetosphere and the associated diamagnetic ring current stretches the field lines throughout the nightside, essentially from dawn to dusk. If the field lines are sufficiently stretched they reconnect and dipolarize, ejecting a plasmoid downtail. This cycle repeats forming multiple sawtooth oscillations. The periodicity of the sawtooth oscillation depends largely upon the strength of the outflow. The strength of outflow is varied in the simulation by changing both the driving conditions (which affects the power flowing into the ionosphere) and through direct modification of the constants in the empirical relationships. Higher outflow fluences produce oscillations with shorter periods. The period of the oscillation is found to vary in the simulations from approximately 2 hours to 6 hours depending upon the strength of the outflow. For a smaller solar wind electric field the outflow fluence is not large enough to stretch the nightside field lines enough for sawtooth oscillations to form and the magnetosphere goes into a steady magnetosphere convection (SMC) mode. As the solar wind electric field increases the outflow fluence becomes sufficiently large to affect the convection in the magnetosphere and generate sawtooth oscillations. The strength

  7. In situ measurements of ionospheric plasma turbulence over five frequency decades: Heritage flight of the Plasma Local Anomalous Noise Experiment (PLANE)

    NASA Astrophysics Data System (ADS)

    Habash Krause, L.; Enloe, C. L.; McHarg, M. G.

    2013-12-01

    Observations of ionospheric plasma density and frequency-dependent broadband plasma turbulence made during the heritage flight of the Plasma Local Anomalous Noise Experiment (PLANE) are presented. Rather than record high frequency time series data, the experiment was designed to record Power Spectral Distributions (PSDs) in five decadal frequency bins with upper limits ranging from 1.0 Hz to 10 kHz. Additionally, PLANE was designed distinguish turbulence in the ambient plasma from that local to the spacecraft. The instrument consists of two retarding potential analyzers (RPAs) connected together via a feedback loop to force one analyzer into the I-V trace retardation region at all times. Fluctuations in this measurement are believed to be ambient only as the RPA's voltage would be too high for locally turbulent plasma to surmount the potential barrier, which is nominally at ram energy. The instrument requires pointing along the spacecraft's ram velocity vector to make this measurement, thus requiring stabilization in pitch and yaw. During PLANE's heritage flight, though the satellite's attitude control system failed early in the mission, plasma data were collected during opportune times in which the instrument rotated into and out of the ram. Observations of plasma density and PSDs of high frequency plasma turbulence were recorded on several occasions. Additionally, a plasma source onboard the satellite was used to generate artificial plasma turbulence, and the PLANE data observed periodic structure presumably associated with the rotation of the spacecraft during these source firings. A brief comparison with other high frequency in situ plasma instruments is presented.

  8. Investigation of methods for updating ionospheric scintillation models using topside in situ plasma density measurements. Final report, 1 May 1990-30 April 1993

    SciTech Connect

    Secan, J.A.

    1993-05-01

    Modern military communication, navigation, and surveillance systems depend on reliable, noise free transionospheric radio-frequency channels and can be severely impacted by small-scale electron-density irregularities in the ionosphere. This report summarizes the results of a three year investigation into the methods for updating ionospheric scintillation models using observations of ionospheric plasma-density irregularities measured by the DMSP Scintillation Meter (SM) sensor. Results are reported from the analysis of data from a campaign conducted in January 1990 near Tromso, Norway, in which near coincident in-situ plasma-density and transionospheric scintillation measurements were made. Estimates for the level of intensity and phase scintillation on a transionospheric UBF radio link in the early-evening auroral zone were calculated from DMSP SM data and compared to the levels actually observed. Results are also presented from a comparison with scintillation observations made with a coincident DNA Polar BEAR satellite pass. Ionosphere, Ionospheric Scintillation, Radiowave Scintillation, Defense Meteorology Satellite Program (DMSP).

  9. Simulation of ionospheric disturbances created by Alfvén waves

    NASA Astrophysics Data System (ADS)

    Sydorenko, D.; Rankin, R.

    2012-09-01

    A two-dimensional numerical model of low-altitude auroral flux tubes has been developed for simulation of coupling between the magnetosphere and the ionosphere. The model considers a realistic ionosphere with multiple ion and neutral species, collisions, cooling and heating processes, as well as the North-South electric field due to the global azimuthal plasma convection. In the paper, a detailed description of the model is given. A representative simulation where the ionosphere is perturbed by an Alfvén wave is discussed. The model demonstrates formation of intense parallel electric fields, radiation of Alfvén waves by density perturbations in the convective flow, and electron and ion heating.

  10. Rice Convection Model Simulation of Injection of an Observed Plasma Bubble Into the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Wolf, R. A.; Zhang, J.; Erickson, G. M.; Toffoletto, F. R.; Yang, J.

    2008-12-01

    An RCM simulation has been carried out for the growth and early expansion phase of a substorm that occurred on July 22, 1998. This is the first substorm simulation for which the RCM boundary conditions and the inputted magnetic field model have been carefully tailored for consistency with measurements made in the inner plasma sheet during the event (Geotail near X=-9, Y=0 in GSM coordinates). The simulation focuses on the injection into the inner magnetosphere of a bubble (region with low specific entropy) that was observed by Geotail. Potential and inductive contributions to the magnetospheric electric field are both important, and their patterns are compared and discussed. One preliminary conclusion from the simulation is that the bubble drifts in a channel that narrows as it approaches the inner magnetosphere, which results in a plasma-sheet inner edge that resembles the injection boundary proposed many years ago by Carl McIlwain. The corresponding distinctive pattern in the auroral electric field is compared with published substorm observations. The model also predicts a distinctive substorm-onset-associated prompt-penetration electric field in the low- and mid-latitude ionosphere.

  11. Magnetospheric Convection as a Global Force Phenomenon

    NASA Astrophysics Data System (ADS)

    Siscoe, G.

    2007-12-01

    Since 1959 when Thomas Gold showed that motions in the magnetosphere were possible despite plasma being frozen to the magnetic field, magnetospheric convection as a subject of study has gone through several stages (to be reviewed) leading to a recent one that integrates convection into a global system of balance of forces. This area of research has opened by focusing on the region 1 current system as a carrier of force between the solar wind and the ionosphere/thermosphere fluid. An important result to emerge from it is the realization that the force that the solar wind delivers to the magnetosphere in being transferred by the region 1 current system to the ionosphere/thermosphere fluid is amplified by about an order of magnitude. (Vasyliunas refers to this as "leveraging.") The apparent violation of Newton's Third Law results from the main participants in the force balance being not the solar wind force but the JxB force on the ionosphere/thermosphere fluid and the mu-dot-grad-B force on the Earth's dipole. This talk extends the study by considering the global force-balance problem separately for the Pedersen current (a completion of the region 1 problem), the Hall current (thus introducing the region 2 current system), and the Cowling current (bringing in the substorm current wedge). The approach is through representing the ionosphere/thermosphere fluid by the shallow water equations. Novelties that result include force balance by means of tidal bulges and tidal bores.

  12. In situ ionospheric observations of severe weather-related gravity waves and associated small-scale plasma structure

    NASA Astrophysics Data System (ADS)

    Kelley, Michael C.

    1997-01-01

    On July 27, 1988, two sounding rockets were launched over a small thunderstorm cell which constituted the remnants of a large frontal event which had lasted for several hours over the eastern seaboard. One of the rockets was instrumented for detection of the electromagnetic impulse from lightning strikes and its subsequent interaction with the ionospheric plasma [Kelley et al., 1990]. The second had on board an absolute electron density probe, the results from which we report here. We present evidence that a gravity wave was spawned by the front and propagated nearly to the F peak in the ionosphere, where it steepened and created structure in the medium at scales much less than the vertical wavenumber of the major disturbance. The fluctuation spectrum along the rocket path was elevated for scales from 25 km down to less than 10 m. At scales between 10 km and just under 100 m, characterization of the spectrum by a power law yields a spectral index less than that displayed by such well-studied processes as bottomside spread F and barium cloud striations. Similar results have been reported for gravity wave induced intermediate scale structures at midlatitudes [Wernik et al., 1986]. The mixing theory described by Fridman [1990] may be relevant to these observations.

  13. Spectral fluctuation analysis of ionospheric inhomogeneities over Brazilian territory. Part I: Equatorial F-region plasma bubbles

    NASA Astrophysics Data System (ADS)

    Fornari, G.; Rosa, R. R.; de Meneses, F. C.; Muralikrishna, P.

    2016-11-01

    In this Part I of a more general paper on the analysis of ionospheric irregularities over Brazilian territory, we apply the Detrended Fluctuation Analysis (DFA) method to evaluate in situ equatorial F-region plasma bubbles events carried out with a sounding rocket over equatorial region in Brazil. The range of scaling exponents derived from the DFA technique are compared to previous results obtained using Power Spectral Density (PSD) technique (which is widely used in this area despite its recognized inaccuracy to analyze short series). The results obtained in this first part of our investigation, using DFA, also show a wide range of spectral index variation with standard deviation of the same order found from the previous application using PSD (σm ≫ 10 %). Therefore, since the dependence of the technique are disregarded, our findings also supports that the observed lack of a universality class characterized by the nonexistence of a single spectral index (with σm ≈ 2 %) may be due to non-homogeneity energy cascades that can appear in the incoherent ionospheric turbulent process.

  14. Electric Field and Plasma Density Observations of Irregularities and Plasma Instabilities in the Low Latitude Ionosphere Gathered by the C/NOFS Satellite

    NASA Technical Reports Server (NTRS)

    Pfaff, Robert F.; Freudenreich, H.; Rowland, D.; Klenzing, J.; Liebrecht, C.

    2012-01-01

    The Vector Electric Field Investigation (VEFI) on the C/NOFS equatorial satellite provides a unique data set which includes detailed measurements of irregularities associated with the equatorial ionosphere and in particular with spread-F depletions. We present vector AC electric field observations gathered on C/NOFS that address a variety of key questions regarding how plasma irregularities, from meter to kilometer scales, are created and evolve. The talk focuses on occasions where the ionosphere F-peak has been elevated above the C/NOFS satellite perigee of 400 km as solar activity has increased. In particular, during the equinox periods of 2011, the satellite consistently journeyed below the F-peak whenever the orbit was in the region of the South Atlantic anomaly after sunset. During these passes, data from the electric field and plasma density probes on the satellite have revealed two types of instabilities which had not previously been observed in the C/NOFS data set: The first is evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. A second result is the appearance of km-scale irregularities that are a common feature in the electric field and plasma density data that also appear when the satellite is near or below the F-peak at night. The vector electric field instrument on C/NOFS clearly shows that the electric field

  15. Simulations of the Solar Wind Interaction with the Atmosphere/Ionosphere of Venus

    NASA Astrophysics Data System (ADS)

    Ledvina, Stephen; Brecht, Stephen H.; Bougher, Stephen W.

    2016-10-01

    The latest results of high resolution 3-D hybrid particle code simulations of the solar wind interacting with the atmosphere/ionosphere of Venus will be presented. The research is focused on understanding the how the solar wind interaction with Venus results in the subsequent ionospheric losses. In addition, the simulations focus on structures caused by the interaction particularly on the pole of the planet where the convection electric field points. A variety of simulation results will be presented each with varying solar wind parameters. The hybrid particle code HALFSHEL contains a variety of physical and chemical models which will also be discussed. These include a chemistry package that produces the ionosphere on grid resolution of 10 km altitude, atmospheric densities and dynamics from the VTGCM code and the Hall and Pedersen conductivities associated with plasma neutral collisions. The specific simulations to be presented trace solar wind protons, and ionospheric O+ and O2+.

  16. Response of the ionosphere thermosphere system to magnetospheric processes

    NASA Astrophysics Data System (ADS)

    Schunk, R. W.; Zhu, L.

    2008-12-01

    The magnetosphere-ionosphere-thermosphere system at high latitudes is strongly coupled via electric fields, particle precipitation, plasma and neutral outflows, and field-aligned currents. Although the climatology of the coupled system is fairly well established, our understanding of the variability of the disturbed state (weather) is rudimentary. This variability is associated with magnetic storms and substorms, nonlinear processes that operate over a range of spatial scales, time delays, and feedback mechanisms between the different domains. The variability and resultant structure of the ionosphere can appear in the form of propagating plasma patches and polar wind jets, pulsing ion and neutral polar winds, auroral and boundary blobs, and ionization channels associated with polar cap arcs, discrete auroral arcs, and storm-enhanced densities (SEDs). The variability and structure of the thermosphere can appear in the form of propagating atmospheric holes, neutral gas fountains, neutral density patches, and transient neutral jets. In addition, during periods of enhanced plasma convection, the neutral winds can become supersonic in relatively narrow regions of the polar cap. The spatial structure in the ionosphere-thermosphere system not only affects the local environment, but the cumulative effect of multiple structures may affect the global circulation and energy balance. A focused topical review of recent results in our modeling the variability and structure of the high-latitude ionosphere-thermosphere system is presented. This review was given at the Greenland Space Science Symposium (May 2007).

  17. Features of the Electromagnetic and Plasma Disturbances Induced at the Altitudes of the Earth's Outer Ionosphere by Modification of the Ionospheric F 2 Region Using High-Power Radio Waves Radiated by the SURA Heating Facility

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Rapoport, V. O.; Schorokhova, E. A.; Belov, A. S.; Parrot, M.; Rauch, J.-L.

    2016-08-01

    In this paper we systematize the results of studying the characteristics of the plasma-density ducts, which was conducted in 2005-2010 during the DEMETER-satellite operation. The ducts are formed at altitudes of about 700 km as a result of the ionospheric F 2 region modification by high-power high-frequency radio waves radiated by the midlatitude SURA heating facility. All the performed measurements are used as the basis for determining the formation conditions for such ducts, the duct characteristics are studied, and the opportunities for the duct influence on the ionosphere-magnetosphere coupling and propagation of radio waves of various frequency ranges are demonstrated. The results of numerical simulation of the formation of such ducts are presented.

  18. Topside ionosphere bubbles, seen as He+ density depletions: connection with ESF, vertical plasma drift, thermosphere wind and solar activity

    NASA Astrophysics Data System (ADS)

    Sidorova, Larissa

    He+ density depletions, considered as originating from equatorial plasma bubbles (PB), or as possible fossil bubble signatures, were involved in this study. He+ density depletions were observed during a high solar activity (1978-79, F10.7 200) at the topside ionosphere altitudes deeply inside the plasmasphere (L 1.3-3) (Karpachev and Sidorova, ASR, 2002; Sidorova, ASR, 2004, 2007). It is suggested that the equatorial F region irregularities, their post sunset development, evolution, and decay processes are controlled by the sunset electrodynamics of the equatorial region. The He+ density depletion peculiarities were considered in connection with equatorial F-spread (ESF) and vertical plasma drift. The depletion values as function of local time (evening-night hours) were compared with the vertical plasma drift velocity variations, obtained for the same periods (1978-79, F10.7 200; AE-E, IS radar, Jicamarca). Striking similarity in development dynamics was revealed for the different seasons. The monthly mean PB occurrence probability, plotted in local time versus month, was compared with the similar plots for global ESF occurrence probability, derived from ISS-b data (1978-79). Good seasonal correlation (R=0.6) was obtained. Moreover, the comparison of the regional maps, derived from ground-based ionograms, obtained over Brazilian regions (Abdu et al., ASR, 2000) for period with the similar solar activity (1980-81, F10.7 230), shows very well correlation (R=0.67). It is also suggested, that the PBs, produced by Rayleigh-Taylor (R-T) instability at the bottomside of ionosphere and transported up to the topside ionosphere/plasmasphere, could be strong affected by meridional wind during a generation due to inhibiting the growth of R-T instability and flux tube integrated conductivity. For better understanding competing/complementary roles of thermospheric winds in the development of PBs, seen as He+ density depletions, the evaluation of the possible influence of the

  19. Plasma Density and Electro-Magnetic Field Perturbations Hf-Induced in the Outer Ionosphere: Review of Experimental Results

    NASA Astrophysics Data System (ADS)

    Frolov, Vladimir; Rauch, Jean-Louis; Parrot, Michel; Rapoport, Victor; Shorokhova, Elena

    In the report we consider features of plasma density and electro-magnetic field perturbations induced in the Earth’s outer ionosphere by modification of F _{2} region by O-mode powerful HF radio waves radiated by the SURA heating facility. Experiments presented were carried out in 2005 - 2010. Plasma density perturbations were detected at altitudes of about of 700 km by instruments onboard the French DEMETER satellite when it intersected the disturbed magnetic flux tube. The formation of artificial HF-induced plasma density ducts in the outer ionosphere is a central discovery, which was made during the SURA-DEMETER experiments [1,2]. Analysis of experimental data available makes it possible to formulate ducts features and point out the conditions under which the formation of such ducts takes place. 1. Under night conditions ducts are characterized by the increased plasma density in the range from 20% to 80% relatively to its background value. As this takes place, the excess in the plasma ion component is due to O (+) ions dominating at altitudes of about 700 km, whereas the densities of lower mass H (+) and He ({+) } ions typically decrease by a percentage amount that is much more the relative increase in the density of O (+) ions. The duct formation was never observed under daytime conditions. According to [3] the HF-induced ducts were observed by ionosphere pumping in morning and evening hours but in these cases their intensity was no more than a few percentages. 2. The size of the ducts along the satellite orbits is of about 80 - 100 km. It is a reason why such ducts can be observed only if the minimal distance between the satellite and the center of the heated flux tube is less than 50 km. 3. The formation of ducts is observed only if the effective radiated power is more than 40 MW. For the SURA facility, to heat the ionosphere at higher efficiency due to the “magnetic-zenith effect”, the HF beam is often inclined by 12 - 16(°) southward. 4. The pump

  20. Application of the Convected Kappa Distribution Function to Hot Plasma Ion Populations Observed in the Magnetospheres of Jupiter and Saturn

    NASA Astrophysics Data System (ADS)

    Kane, M.; Mitchell, D. G.; Mauk, B.; Carbary, J. F.; Krimigis, S. M.

    2015-12-01

    The Voyager, Galileo, and Cassini missions have measured the hot ion plasma pervading the magnetospheres of Jupiter and Saturn. In the middle and outer regions, the convected kappa distribution function, with isotropy in the rest (subcorotating with the planet) frame, has been found to fit hot ion particle distributions well and has been useful for extracting physical plasma parameters including the vector bulk velocity and the characteristic energy (temperature) of the distribution. The kappa model of the plasma distribution function using hydrogen and oxygen ions (Saturn) and hydrogen, oxygen, and sulfur ions (Jupiter) applied to observations generally indicates the presence of a hot ion population, energized in inner regions and adiabatically transported to the outer regions, but with significant exceptions. Higher mass species generally have a higher temperature. From the anisotropy of the distribution in the spacecraft frame, vector bulk velocity may be determined. From this analysis rotation curves for the plasma disks at Jupiter and Saturn reveal a plasma with significant subcorotation with a fraction that falls with increasing distance from the planet. There are local time asymmetries observed in the radial convection pattern. The plasma azimuthal convection patterns at Jupiter and Saturn and the characteristic temperature profiles are remarkably similar when scaled by the magnetopause distance and radial size of the planets.

  1. Low latitude ionospheric scintillation and zonal plasma irregularity drifts climatology around the equatorial anomaly crest over Kenya

    NASA Astrophysics Data System (ADS)

    Olwendo, O. J.; Baki, P.; Cilliers, P. J.; Doherty, P.; Radicella, S.

    2016-02-01

    In this study we have used a VHF and GPS-SCINDA receiver located at Nairobi (36.8°E, 1.3°S, dip -24.1°) in Kenya to investigate the climatology of ionospheric L-band scintillation occurrences for the period 2009 to 2012; and seasonal variation of the zonal plasma drift irregularities derived from a VHF receiver for the period 2011. The annual and diurnal variations of L-band scintillation indicate occurrence at post sunset hours and peaks in the equinoctial months. However VHF scintillation occurs at all seasons around the year and is characterized by longer duration of activity and a slow fading that continues till early morning hours unlike in the L-band where they cease after midnight hours. A directional analysis has shown that the spatial distribution of scintillation events is mainly on the Southern and Western part of the sky over Nairobi station closer to the edges of the crest of the Equatorial Ionization Anomaly. The distribution of zonal drift velocities of the VHF related scintillation structures indicates that they move at velocities in the range of 20-160 m/s and their dimension in the East-West direction is in the range of 100-00 km. The December solstice is associated with the largest plasma bubbles in the range of 600-900 km. The most significant observation from this study is the occurrence of post-midnight scintillation without pre-midnight scintillations during magnetically quiet periods. The mechanism leading to the formation of the plasma density irregularity causing scintillation is believed to be via the Rayleigh Tailor Instability; it is however not clear whether we can also attribute the post-midnight plasma bubbles during magnetic quiet times to the same mechanism. From our observations in this study, we suggest that a more likely cause of the east ward zonal electric fields at post-midnight hours is the coupling of the ionosphere with the lower atmosphere during nighttime. This however needs a further investigation based on relevant

  2. Ionospheric vertical plasma drift perturbations due to the quasi 2 day wave

    NASA Astrophysics Data System (ADS)

    Gu, Sheng-Yang; Liu, Han-Li; Li, Tao; Dou, Xiankang

    2015-05-01

    The thermosphere-ionosphere-mesosphere-electrodynamics-general circulation model is utilized to study the vertical E × B drift perturbations due to the westward quasi 2 day wave with zonal wave numbers 2 and 3 (W2 and W3). The simulations show that both wind components contribute directly and significantly to the vertical drift, which is not merely confined to low latitudes. The vertical drifts at the equator induced by the total wind perturbations of W2 are comparable with that at middle latitudes, while the vertical drifts from W3 are much stronger at middle latitudes than at the equator. The ion drift perturbations induced by the zonal and meridional wind perturbations of W2 are nearly in-phase with each other, whereas the phase discrepancies of the ion drift induced by the individual wind component of W3 are much larger. This is because the wind perturbations of W2 and W3 have different latitudinal structures and phases, which result in different ionospheric responses through wind dynamo.

  3. Ionospheric irregularity physics modelling

    SciTech Connect

    Ossakow, S.L.; Keskinen, M.J.; Zalesak, S.T.

    1982-01-01

    Theoretical and numerical simulation techniques have been employed to study ionospheric F region plasma cloud striation phenomena, equatorial spread F phenomena, and high latitude diffuse auroral F region irregularity phenomena. Each of these phenomena can cause scintillation effects. The results and ideas from these studies are state-of-the-art, agree well with experimental observations, and have induced experimentalists to look for theoretically predicted results. One conclusion that can be drawn from these studies is that ionospheric irregularity phenomena can be modelled from a first principles physics point of view. Theoretical and numerical simulation results from the aforementioned ionospheric irregularity areas will be presented.

  4. Ionospheric storms on Mars

    NASA Astrophysics Data System (ADS)

    Dubinin, E.; Fraenz, M.; Woch, J.; Duru, F.; Gurnett, D.; Modolo, R.; Barabash, S.; Lundin, R.

    2009-04-01

    Measurements made by the ASPERA-3 and MARSIS experiments on Mars Express have shown that space weather effects related to the impact of a dense and high pressure solar wind on Mars cause strong perturbations in the martian induced magnetosphere and ionosphere. The magnetic barrier formed by pile-up of the draped interplanetary magnetic field ceases to be a shield for the incoming solar wind. Large blobs of solar wind plasma penetrate to the magnetosphere and sweep out dense plasma from the ionosphere. The topside martian ionosphere becomes very fragmented consisting of intermittent cold/low energy and energized plasmas. The scavenging effect caused by the intrusions of solar wind plasma clouds enhances significantly the losses of volatile material from Mars.

  5. Measurements And Particle In Cell vs. Fluid Simulations Of A New Time Domain Impedance Probe For Ionospheric Plasma Characterization

    NASA Astrophysics Data System (ADS)

    Spencer, E. A.; Russ, S.; Kerrigan, B.; Leggett, K.; Mullins, J.; Clark, D. C.; Mizell, J.; Gollapalli, R.; Vassiliadis, D.; Lusk, G. D.

    2015-12-01

    A plasma impedance probe is used to obtain plasma parameters in the ionosphere by measuring the magnitude, shape and location of resonances in the frequency spectrum when a probe structure is driven with RF excitation. The measured magnitude and phase response with respect to frequency can be analyzed via analytical and simulational means. We have designed and developed a new Time Domain Impedance Probe capable of making measurements of absolute electron density and electron neutral collision frequency at temporal and spatial resolutions not previously attained. A single measurement can be made in a time as short as 50 microseconds, which yields a spatial resolution of 0.35 meters for a satellite orbital velocity of 7 km/s. The method essentially consists of applying a small amplitude time limited voltage signal into a probe and measuring the resulting current response. The frequency bandwidth of the voltage signal is selected in order that the electron plasma resonances are observable. A prototype of the instrument will be flown in October 2015 on a NASA Undergraduate Student Instrument Progam (USIP) sounding rocket launched out of Wallops Flight Facility. To analyze the measurements, we use a Particle In Cell (PIC) kinetic simulation to calculate the impedance of a dipole antenna immersed in a plasma. The electromagnetic solver utilizes the Finite Difference Time Domain method, while the particle to grid and grid to particle interpolation schemes are standard. The plasma sheath formation electron flux into the dipole surface is not included. The bulk velocity of the plasma around the dipole is assumed to be zero. For completeness, the hot plasma and nonlinear effects of probe plasma interaction are explored, including the appearance of cyclotron harmonics. In this work the electron neutral collisions are simulated via a Poisson process approximation. Our results are compared to sounding rocket data from the NASA Tropical Storms mission in 2007, as well as the

  6. Ionospheric Response to Flux Transfer Events at the Earth's Magnetopause

    NASA Astrophysics Data System (ADS)

    Pitout, F.; Blelly, P. L.

    2003-06-01

    Flux transfer events (FTE) are thought to be the manifestation of the pulsed reconnection process by which interplanetary magnetic field lines and Earth's magnetic field lines merge. They are observed at the magnetopause as bipolar signatures in the magnetic field component perpendicular to the magnetopause (normal component) as the distorted newly reconnected field lines get dragged by the magnetic tension and the solar wind. FTEs are also observed in the ionosphere by ground-based instrumentations. Optical instruments commonly record poleward moving auroral forms in the red line (630nm) corresponding to low-energy electron precipitation. SuperDARN radars observe the convection associated to FTEs as enhanced flow channels. The EISCAT radars on the Svalbard archipelago have revealed the transient and impulsive nature of the ionosphere under the polar cusp for southward IMF. We have performed a simulation of the ionospheric footprint of a FTE by including the Southwood model of FTE in the TRANSCAR model of ionosphere. We can trace the evolution of an open flux tube and the behaviour and dynamics of the surrounding ionospheric plasma. We particularly focus on the signature of the two areas of return flow on both side of the FTE footprint. Those return flow may actually be responsible of some of the structures observed by Incoherent Scatter radars such as the Eiscat Svalbard Radar (ESR). We then compare our simulations with observations and finally discuss the pros and cons of the Southwood model of FTE.

  7. The effect of longitudinal conductance variations on the ionospheric prompt penetration electric fields

    NASA Astrophysics Data System (ADS)

    Sazykin, S.; Wolf, R.; Spiro, R.; Fejer, B.

    Ionospheric prompt penetration electric fields of magnetospheric origin, together with the atmospheric disturbance dynamo, represent the most important parameters controlling the storm-time dynamics of the low and mid-latitude ionosphere. These prompt penetration fields result from the disruption of region-2 field-aligned shielding currents during geomagnetically disturbed conditions. Penetration electric fields con- trol, to a large extent, the generation and development of equatorial spread-F plasma instabilities as well as other dynamic space weather phenomena in the ionosphere equatorward of the auroral zone. While modeling studies typically agree with average patterns of prompt penetration fields, experimental results suggest that longitudinal variations of the ionospheric con- ductivities play a non-negligible role in controlling spread-F phenomena, an effect that has not previously been modeled. We present first results of modeling prompt pene- tration electric fields using a version of the Rice Convection Model (RCM) that allows for longitudinal variations in the ionospheric conductance tensor. The RCM is a first- principles numerical ionosphere-magnetosphere coupling model that solves for the electric fields, field-aligned currents, and particle distributions in the ionosphere and inner/middle magnetosphere. We compare these new theoretical results with electric field observations.

  8. Equatorial ionospheric plasma drifts and O+ concentration enhancements associated with disturbance dynamo during the 2015 St. Patrick's Day magnetic storm

    NASA Astrophysics Data System (ADS)

    Huang, Chao-Song; Wilson, Gordon R.; Hairston, Marc R.; Zhang, Yongliang; Wang, Wenbin; Liu, Jing

    2016-08-01

    Disturbance dynamo is an important dynamic process during magnetic storms. However, very few direct observations of dynamo-induced plasma drifts and ion composition changes in the equatorial ionosphere are available. In this study, we use measurements of the Defense Meteorological Satellite Program (DMSP) satellites to identify the characteristics of the disturbance dynamo process in the topside equatorial ionosphere near dawn during the magnetic storm with a minimum Dst of -223 nT on 17 March 2015. Data from four DMSP satellites with equatorial crossings at 0245, 0430, 0630, and 0730 LT are available for this case. The dynamo process was first observed in the postmidnight sector 3-4.7 h after the beginning of the storm main phase and lasted for 31 h, covering the second storm intensification and the initial 20 h of the recovery phase. The dynamo vertical ion drift was upward (up to 150-200 m s-1) in the postmidnight sector and downward (up to ~80 m s-1) in the early morning sector. The dynamo zonal ion drift was westward at these locations and reached ~100 m s-1. The dynamo process caused large enhancements of the O+ concentration (the ratio of the oxygen ion density to the total ion density) at the altitude of 840 km near dawn. The O+ concentration increased from below 60% during the prestorm period to 80-90% during the storm time. More specifically, the O+ density was increased, and the H+ density was decreased. The variations of the O+ concentration were well correlated with the vertical ion drift.

  9. High latitude field aligned light ion flows in the topside ionosphere deduced from ion composition and plasma temperatures

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Hoegy, W. R.; Chen, T. C.

    1993-01-01

    Using a comprehensive ionospheric data set comprised of all available ion composition and plasma temperature measurements from satellites, the vertical distributions of ion composition and plasma temperatures are defined from middle latitudes up into the polar cap for summer conditions for altitudes below about 1200 km. These data are sufficient to allow a numerical estimation of the latitudinal variation of the light ion outflows from within the plasmasphere to the polar wind regions. The altitude at which significant light ion outflow begins is found to be lower during solar minimum conditions than during solar maximum. The H(+) outward speeds are of the order of 1 km/s near 1100 km during solar maximum but attain several km/s speeds for solar minimum. He(+) shows a similar altitude development of flow but attains polar cap speeds much less than 1 km/s at altitudes below 1100 km, particularly under solar maximum conditions. Outward flows are also found in the topside F-region for noontime magnetic flux tubes within the plasmasphere.

  10. An investigation of mechanisms other than lightning to explain certain wideband plasma wave bursts detected in the Venusian nightside ionosphere

    NASA Technical Reports Server (NTRS)

    Carpenter, D. L.

    1992-01-01

    Several related topics are briefly discussed. Reviewed here is work on an investigation of plasma wave phenomena associated with the question of lightning on Venus. The work supported the contention that lightning is at least a candidate explanation for many of the 100 Hz-only Pioneer Venus orbital electric field detector (OEFD) signals. A review of the work on the investigation of mechanisms other than lightning to explain certain wideband plasma wave bursts detected in the Venusian nightside ionosphere is given. A summary is given of our analysis of data from 23 OEFD observing periods as well as a discussion of the properties of specifically multifrequency events. Our opportunity to work on this topic was not sufficient to draw any firm conclusions about the origins of the multifrequency bursts, but we call attention to what we consider to be several candidate sources. Also discussed are case studies to test for evidence of whistler mode propagation from subionospheric sources, results of a search for dispersive effects in the OEFD data, the results for a search for simultaneous 100 Hz and 730 Hz observations at altitudes below 150 km, changes with altitude in dispersive broadening effects in the time signatures of 100 Hz bursts, and a survey of activity at altitudes above 1000 km.

  11. Numerical model of the highlatitude ionosphere taking into account the solar wind parameters

    NASA Astrophysics Data System (ADS)

    Uvarov, Viacheslav Mikhailovich; Lukianova, Renata

    The high latitude ionosphere is driven by both magnetospheric and solar UV inputs and, therefore, quite variable and poor predictable. Empirical models are unable to describe these complex dependencies while physics-based mathematical models are more successful in reproducing the plasma density features. In this contribution we present a numerical model of the polar ionosphere. The three-dimensional model covers the E-region, F-region and topside poleward of 40° latitude in the altitude range from 90 km to 650 km. The main output is an electron density distribution at a specified times and under a specified solar wind conditions. The model consists of two blocks: calculation the convection electric field and calculation of the ionospheric plasma parameters. The convection block includes an analytical representation of the large-scale convection patterns and their dependence on the interplanetary magnetic field (IMF) orientation. The density distributions of O+ and generalized ion species are obtained from a numerical solution of the appropriate continuity equations as a function of height. The empirical model is used to calculate the thermospheric temperature, composition, and density. Flux tubes of plasma are followed as they convect and corotate through a moving neutral atmosphere during many hours. The offset between the geomagnetic and geographic poles are also taken into account. Model simulations for different IMF conditions, solar cycle, season, universal time (UT) and magnetic activity were used to elucidate the evolution of the high latitude ionospheric morphological features. The global features such as the tongue of ionization, plasma cavity, polar and auroral peaks are well reproduced and quantified. Model electron density profiles are compared with observations using the EISCAT incoherent scatter radar and ionosonde.

  12. Stimulated Electromagnetic Emission Indicator of Glow Plasma Discharges from Ionospheric HF Wave Transmissions with HAARP

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Scales, W.; Briczinski, S. J.; Fu, H.; Mahmoudian, A.; Samimi, A.

    2012-12-01

    High power radio waves resonantly interact with to accelerate electrons for production of artificial aurora and plasma clouds. These plasma clouds are formed when the HF frequency is tuned near a harmonic of the electron cyclotron frequency. At a narrow band resonance, large electrostatic fields are produced below the F-layer and the neutral atmosphere breaks down with a glow plasma discharge. The conditions for this resonance are given by matching the pump wave frequency and wave-number with the sum of daughter frequencies and wave-numbers for several plasma modes. The most likely plasma mode that accelerates the electrons is the electron Bernstein wave in conjunction with an ion acoustic wave. Both upper hybrid and whistler mode waves are also possible sources of electron acceleration. To determine the plasma process for electron acceleration, stimulated electromagnetic emissions are measured using ground receivers in a north-south chain from the HAARP site. Recent observations have shown that broad band spectral lines downshifted from the HF pump frequency are observed when artificial plasma clouds are formed. For HF transmissions are the 2nd, 3rd, and 4th gyro harmonic, the downshifted indicators are found 500 Hz, 20 kHz, and 140 kHz, respectively, from the pump frequency. This Indicator Mode (IM) anticipates that a plasma layer will be formed before it is recorded with an ionosonde or optical imager.

  13. A high-latitude, low-latitude boundary layer model of the convection current system

    SciTech Connect

    Siscoe, G.L. ); Lotko, W.; Sonnerup, B.U.O. )

    1991-03-01

    Observations suggest that both the high- and low-latitude boundary layers contribute to magnetospheric convection, and that their contributions are linked. In the interpretation pursued here, the high-latitude boundary layer (HBL) generates the voltage while the low-latitude boundary layer (LBL) generates the current for the part of the convection electric circuit that closes through the ionosphere. This paper gives a model that joins the high- and low-latitude boundary layers consistently with the ionospheric Ohm's law. It describes an electric circuit linking both boundary layers, the region 1 Birkeland currents, and the ionospheric Pedersen closure currents. The model works by using the convection electric field that the ionosphere receives from the HBL to determine two boundary conditions to the equations that govern viscous LBL-ionosphere coupling. The result provides the needed self-consistent coupling between the two boundary layers and fully specifies the solution for the viscous LBL-ionosphere coupling equations. The solution shows that in providing the current required by the ionospheric Ohm's law, the LBL needs only a tenth of the voltage that spans the HBL. The solution also gives the latitude profiles of the ionospheric electric field, parallel currents, and parallel potential. It predicts that the plasma in the inner part of the LBL moves sunward instead of antisunward and that, as the transpolar potential decreases below about 40 kV, reverse polarity (region 0) currents appear at the poleward border of the region 1 currents. A possible problem with the model is its prediction of a thin boundary layer ({approximately}1000 km), whereas thicknesses inferred from satellite data tend to be greater.

  14. Plasma modifications induced by an X-mode HF heater wave in the high latitude F region of the ionosphere

    NASA Astrophysics Data System (ADS)

    Blagoveshchenskaya, N. F.; Borisova, T. D.; Yeoman, T. K.; Rietveld, M. T.; Häggström, I.; Ivanova, I. M.

    2013-12-01

    We presented experimental results of strong plasma modifications induced by X-mode powerful HF radio waves injected towards the magnetic zenith into the high latitude F region of the ionosphere. The experiments were conducted in 2009-2011 using the EISCAT Heating facility, UHF incoherent scatter radar and the EISCAT ionosonde at Tromsø, Norway; and the CUTLASS SuperDARN HF coherent radar at Hankasalmi, Finland. The results showed that the X-mode HF pump wave can generate strong small-scale artificial field aligned irregularities (AFAIs) in the F region of the high-latitude ionosphere. These irregularities, with spatial scales across the geomagnetic field of the order of 9-15 m, were excited when the heater frequency (fH) was above the ordinary-mode critical frequency (foF2) by 0.1-1.2 MHz. It was found that the X-mode AFAIs appeared between 10 s and 4 min after the heater is turned on. Their decay time varied over a wide range between 3 min and 30 min. The excitation of X-mode AFAIs was accompanied by electron temperature (Te) enhancements and an increase in the electron density (Ne) depending on the effective radiated power (ERP). Under ERPs of about 75-180 MW the Te enhances up to 50% above the background level and an increase in Ne of up to 30% were observed. Dramatic changes in the Te and Ne behavior occurred at effective radiated powers of about 370-840 MW, when the Ne and Te values increased up to 100% above the background ones. It was found that AFAIs, Ne and Te enhancements occurred, when the extraordinary-mode critical frequency (fxF2) lied in the frequency range fH-fce/2≤fxF2≤fH+fce/2, where fce is the electron gyrofrequency. The strong Ne enhancements were observed only in the magnetic field-aligned direction in a wide altitude range up to the upper limit of the UHF radar measurements. In addition, the maximum value of Ne is about 50 km higher than the Te enhancement peak. Such electron density enhancements (artificial ducts) cannot be explained by

  15. Plasma Transport in Saturn's Inner Magnetosphere: Transition from Small-scale to Large-scale Interchange Convection Cells

    NASA Astrophysics Data System (ADS)

    Hill, T. W.; Jaggi, A.; Sazykin, S. Y.; Wolf, R.

    2015-12-01

    Rice Convection Model simulations of plasma transport in Saturn's inner magnetosphere (2 < L < 12) with an imposed source of cool plasma distributed in the range 5 < L < 10 typically exhibit a chaotic interchange convection pattern with narrow outflow channels of cool dense plasma interspersed with even narrower inflow channels of hot tenuous plasma from the outer magnetosphere. We have now extended these simulations to a larger range of L (2 < L < 20) and to much longer simulation times, T ~ 1000 hours ~ 20 circulation time scales. At times greater than a few circulation time scales the simulations reveal a new type of behavior in the outer region, with many narrow fingers coalescing to form fewer but broader outflow fingers. The Fourier spectrum of the azimuthal convection structure, initially dominated by azimuthal wavenumbers m ~ 20 - 40, becomes dominated instead by wavenumbers m ~ 1. Work is in progress to understand this behavior at an analytical level, and to investigate its possible role in producing spin-periodic phenomena in Saturn's otherwise symmetric magnetosphere.

  16. Macroscopic time and altitude distribution of plasma turbulence induced in ionospheric modification experiments

    SciTech Connect

    Rose, H.; Dubois, D.; Russell, D.; Hanssen, A.

    1996-03-01

    This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This research concentrated on the time dependence of the heater, induced-turbulence, and electron-density profiles excited in the ionosphere by a powerful radio-frequency heater wave. The macroscopic density is driven by the ponderomotive pressure and the density self-consistently determines the heater propagation. For typical parameters of the current Arecibo heater, a dramatic quasi-periodic behavior was found. For about 50 ms after turn-on of the heater wave, the turbulence is concentrated at the first standing-wave maximum of the heater near reflection altitude. From 50--100 ms the standing-wave pattern drops by about 1--2 km in altitude and the quasi-periodicity reappears at the higher altitudes with a period of roughly 50 ms. This behavior is due to the half-wavelength density depletion grating that is set up by the ponderomotive pressure at the maxima of the heater standing-wave pattern. Once the grating is established the heater can no longer propagate to higher altitudes. The grating is then unsupported by the heater at these altitudes and decays, allowing the heater to propagate again and initiate another cycle. For stronger heater powers, corresponding to the Arecibo upgrade and the HAARP heater now under construction, the effects are much more dramatic.

  17. Branches of electrostatic turbulence inside solitary plasma structures in the auroral ionosphere

    SciTech Connect

    Golovchanskaya, Irina V.; Kozelov, Boris V.; Chernyshov, Alexander A.; Mogilevsky, Mikhail M.; Ilyasov, Askar A.

    2014-08-15

    The excitation of electrostatic turbulence inside space-observed solitary structures is a central topic of this exposition. Three representative solitary structures observed in the topside auroral ionosphere as large-amplitude nonlinear signatures in the electric field and magnetic-field-aligned current on the transverse scales of ∼10{sup 2}–10{sup 3} m are evaluated by the theories of electrostatic wave generation in inhomogeneous background configurations. A quantitative analysis shows that the structures are, in general, effective in destabilizing the inhomogeneous energy-density-driven (IEDD) waves, as well as of the ion acoustic waves modified by a shear in the parallel drift of ions. It is demonstrated that the dominating branch of the electrostatic turbulence is determined by the interplay of various driving sources inside a particular solitary structure. The sources do not generally act in unison, so that their common effect may be inhibiting for excitation of electrostatic waves of a certain type. In the presence of large magnetic-field-aligned current, which is not correlated to the inhomogeneous electric field inside the structure, the ion-acoustic branch becomes dominating. In other cases, the IEDD instability is more central.

  18. Observed and modelled effects of auroral precipitation on the thermal ionospheric plasma: comparing the MICA and Cascades2 sounding rocket events

    NASA Astrophysics Data System (ADS)

    Lynch, K. A.; Gayetsky, L.; Fernandes, P. A.; Zettergren, M. D.; Lessard, M.; Cohen, I. J.; Hampton, D. L.; Ahrns, J.; Hysell, D. L.; Powell, S.; Miceli, R. J.; Moen, J. I.; Bekkeng, T.

    2012-12-01

    Auroral precipitation can modify the ionospheric thermal plasma through a variety of processes. We examine and compare the events seen by two recent auroral sounding rockets carrying in situ thermal plasma instrumentation. The Cascades2 sounding rocket (March 2009, Poker Flat Research Range) traversed a pre-midnight poleward boundary intensification (PBI) event distinguished by a stationary Alfvenic curtain of field-aligned precipitation. The MICA sounding rocket (February 2012, Poker Flat Research Range) traveled through irregular precipitation following the passage of a strong westward-travelling surge. Previous modelling of the ionospheric effects of auroral precipitation used a one-dimensional model, TRANSCAR, which had a simplified treatment of electric fields and did not have the benefit of in situ thermal plasma data. This new study uses a new two-dimensional model which self-consistently calculates electric fields to explore both spatial and temporal effects, and compares to thermal plasma observations. A rigorous understanding of the ambient thermal plasma parameters and their effects on the local spacecraft sheath and charging, is required for quantitative interpretation of in situ thermal plasma observations. To complement this TRANSCAR analysis we therefore require a reliable means of interpreting in situ thermal plasma observation. This interpretation depends upon a rigorous plasma sheath model since the ambient ion energy is on the order of the spacecraft's sheath energy. A self-consistent PIC model is used to model the spacecraft sheath, and a test-particle approach then predicts the detector response for a given plasma environment. The model parameters are then modified until agreement is found with the in situ data. We find that for some situations, the thermal plasma parameters are strongly driven by the precipitation at the observation time. For other situations, the previous history of the precipitation at that position can have a stronger

  19. Adiabatic Betatron deceleration of ionospheric charged particles: a new explanation for (i) the rapid outflow of ionospheric O ions, and for (ii) the increase of plasma mass density observed in magnetospheric flux tubes during main phases of geomagnetic s

    NASA Astrophysics Data System (ADS)

    Lemaire, Joseph; Pierrard, Viviane; Darrouzet, Fabien

    2013-04-01

    Using European arrays of magnetometers and the cross-phase analysis to determine magnetic field line resonance frequencies, it has been found by Kale et al. (2009) that the plasma mass density within plasmaspheric flux tubes increased rapidly after the SSC of the Hallowe'en 2003 geomagnetic storms. These observations tend to confirm other independent experimental results, suggesting that heavy ion up-flow from the ionosphere is responsible for the observed plasma density increases during main phases of geomagnetic storms. The aim of our contribution is to point out that, during main phases, reversible Betatron effect induced by the increase of the southward Dst-magnetic field component (|Δ Bz|), diminishes slightly the perpendicular kinetic energy (W?) of charged particles spiraling along field lines. Furthermore, due to the conservation of the first adiabatic invariant (μ = Wm/ Bm) the mirror points of all ionospheric ions and electrons are lifted up to higher altitudes i.e. where the mirror point magnetic field (Bm) is slightly smaller. Note that the change of the mirror point altitude is given by: Δ hm = -1/3 (RE + hm) Δ Bm / Bm. It is independent of the ion species and it does not depend of their kinetic energy. The change of kinetic energy is determined by: Δ Wm = Wm Δ Bm / Bm. Both of these equations have been verified numerically by Lemaire et al. (2005; doi: 10.1016/S0273-1177(03)00099-1) using trajectory calculations in a simple time-dependant B-field model: i.e. the Earth's magnetic dipole, plus an increasing southward B-field component: i.e. the Dst magnetic field whose intensity becomes more and more negative during the main phase of magnetic storms. They showed that a variation of Bz (or Dst) by more than - 50 nT significantly increases the mirror point altitudes by more than 100 km which is about equal to scale height of the plasma density in the topside ionosphere where particles are almost collisionless (see Fig. 2 in Lemaire et al., 2005

  20. Characterizing ISS Charging Environments with On-Board Ionospheric Plasma Measurements

    NASA Technical Reports Server (NTRS)

    Minow, Jospeh I.; Craven, Paul D.; Coffey, Victoria N.; Schneider, Todd A.; Vaughn, Jason A.; Wright Jr, Kenneth; Parker, Paul D.; Mikatarian, Ronald R.; Kramer, Leonard; Hartman, William A.; Alred, John W.; Koontz, Steven L.

    2008-01-01

    Charging of the International Space Station (ISS) is dominated by interactions of the biased United States (US) 160 volt solar arrays with the relatively high density, low temperature plasma environment in low Earth orbit. Conducting surfaces on the vehicle structure charge negative relative to the ambient plasma environment because ISS structure is grounded to the negative end of the US solar arrays. Transient charging peaks reaching potentials of some tens of volts negative controlled by photovoltaic array current collection typically occur at orbital sunrise and sunset as well as near orbital noon. In addition, surface potentials across the vehicle structure vary due to an induced v x B (dot) L voltage generated by the high speed motion of the conducting structure across the Earth's magnetic field. Induced voltages in low Earth orbit are typically only approx.0.4 volts/meter but the approx.100 meter scale dimensions of the ISS yield maximum induced potential variations ofapprox.40 volts across the vehicle. Induced voltages are variable due to the orientation of the vehicle structure and orbital velocity vector with respect to the orientation of the Earth's magnetic field along the ISS orbit. In order to address the need to better understand the ISS spacecraft potential and plasma environments, NASA funded development and construction of the Floating Potential Measurement Unit (FPMU) which was deployed on an ISS starboard truss arm in August 2006. The suite of FPMU instruments includes two Langmuir probes, a plasma impedance probe, and a potential probe for use in in-situ monitoring of electron temperatures and densities and the vehicle potential relative to the plasma environment. This presentation will describe the use of the FPMU to better characterize interactions of the ISS with the space environment, changes in ISS charging as the vehicle configuration is modified during ISS construction, and contributions of FPMU vehicle potential and plasma environment

  1. Characteristics of ionospheric plasma drifts as obtained from Doppler ionosonde measurements at magnetic equator over Indian sector

    NASA Astrophysics Data System (ADS)

    Samireddipalle, Sripathi; Banola, Sridhar; Singh, Ram

    2016-07-01

    We present equatorial plasma drifts over Tirunelveli (8.73°N, 77.70°E; Dip 0.5°N), an equatorial site over Indian region using Doppler interferometry technique of Canadian Advanced Digital Ionosonde (CADI) system. In the Doppler interferometry technique, it is possible to infer three dimensional bulk motion of the scatterers as reflected from the ionosphere at selected frequencies using spaced receivers arranged in mag. east-west, north-south directions. Spectral phases and amplitudes are calculated using FFT to identify the Doppler frequencies and their drifts. This technique produces reliable drifts when sharp refractive index gradients exists which produces higher scattering sources. The vertical drifts so obtained are compared with same drifts from Digisonde at Trivandrum. After having compared with Digisonde drifts, we studied the temporal and seasonal variability of these drifts during quiet periods for the year 2012. It is seen that vertical drifts exhibited equinoctial maximum in the Pre-Reversal-Enhancement (PRE) followed by winter and summer respectively. A comparison of these vertical drifts is made with drifts obtained from (a) virtual height measured at 4 MHz and (b) Fejer drift model. The comparison suggests that Doppler vertical drifts are relatively higher as compared to the drifts obtained from model and virtual height. However, the correlation seems to be good around evening PRE times. The zonal drifts, on the other hand, showed westward drifts during daytime with mean drifts of ~250 m/s, while they are eastward during nighttime with mean drifts of ~150 m/s. These drifts seems to be higher as compared to zonal drifts obtained in the South American sector. However, the zonal drifts so obtained showed good correlation with Equatorial Electrojet (EEJ) strength suggesting zonal drifts are influenced by E region drifts during daytime in agreement with Woodman et al., 2013 paper. The magnitude of these drifts are comparable to other independent

  2. Investigation of methods for updating ionospheric scintillation models using topside in-situ plasma-density measurements. Rept. for 1 May 90-30 Apr 91

    SciTech Connect

    Secan, J.A.

    1991-05-15

    Modern military communication, navigation, and surveillance systems depend on reliable, noise-free transionospheric radio-frequency channels. They can be severely impacted by small-scale electron-density irregularities in the ionosphere, which cause both phase and amplitude scintillation. Basic tools used in planning and mitigation schemes are climatological in nature and thus may greatly over- and under-estimate the effects of scintillation in a given scenario. This report summarizes the results of the first year of a three-year investigation into the methods for updating ionospheric scintillation models using observations of ionospheric plasma-density irregularities measured by DMSP Scintillation Meter (SM) sensor. Results are reported from the analysis of data from a campaign conducted in January 1990 near Tromso, Norway, in which near coincident in-situ plasma-density and transionospheric scintillation measurements were made. Estimates for the level of intensity and phase scintillation on a transionospheric UHF radio link in the early-evening auroral zone were calculated from DMSP SM data and compared to the levels actually observed.

  3. Longitudinal and Seasonal Variations in Nighttime Plasma Temperatures in the Equatorial Topside Ionosphere During Solar Maximum

    NASA Technical Reports Server (NTRS)

    Venkatraman, Sarita; Heelis, Rod

    1999-01-01

    Latitude profiles of the ion and electron temperatures and total ion concentration across the equatorial region near 800 km altitude are routinely obtained from Defense Meteorological Satellite Program (DMSP) spacecraft. We have examined these profiles at 2100 hours local time to discover the influences of field-aligned plasma transport induced by F region neutral winds. Such dependencies are readily seen by contrasting observations at different seasons and different longitudes distinguished by different magnetic declinations. These data show strong evidence for adiabatic heating produced by interhemispheric plasma transport. This heating manifests itself as a local temperature maximum that appears in the winter hemisphere during the solstices and is generally absent during equinox. A longitudinal variation in the appearance of this maximum is consistent with the roles of meridional and zonal winds in modulating the field-aligned plasma velocities. The data also show a local temperature minimum near the dip equator. However, it is not so easy to attribute this minimum to adiabatic cooling since transport of plasma from below and the latitude variation in the flux tube content may also produce such a minimum.

  4. A study of the cleft region using synoptic ionospheric plasma data obtained by the polar orbiting satellites Aeros-B and Isis-2

    NASA Technical Reports Server (NTRS)

    Kist, R.; Klumpar, D.

    1980-01-01

    The concentrations of O(+) and NO(+) in the dayside high-latitude cleft region of the ionosphere are investigated based on synoptic particle and plasma measurements obtained by the polar orbiting Aeros-B and Isis-2 satellites. At a time when the orbital planes of the satellites are almost at right angles to each other, three maxima in ion temperature are observed, with two of them accompanied by an increased electron temperature and electron density irregularities, and the density of the molecular ions NO(+) and O2(+) is found to increase at the expense of O(+) density. Results are discussed in terms of a theory relating perpendicular electric fields to oxygen atom reaction rates. Systematic analysis of the Aeros data base reveals 14 additional instances of O(+) to NO(+) conversion, with a large variety of forms and structures reflecting the complex structure and dynamics of the high-latitude dayside ionosphere.

  5. Cross-B convection of artificially created, negative-ion clouds and plasma depressions - Low-speed flow

    NASA Technical Reports Server (NTRS)

    Bernhardt, Paul A.

    1988-01-01

    A negative-ion, positive-ion plasma produced by the release of an electron attachment chemical into the F region becomes electrically polarized by collisions with neutrals moving across magnetic field lines. The resulting electric field causes E x B drift of the two ion species and the residual electrons. The cross-field flow of the modified ionosphere is computed using a two-dimensional numerical simulation which includes electron attachment and mutual neutralization chemistry, self-consistent electric fields, and three-species plasma transport. The velocity of the plasma is initially in the direction of the neutral wind because the negative-ion cloud is a Pedersen conductivity enhancement. As the positive and negative ions react, the Pedersen conductivity becomes depressed below the ambient value and the velocity of the plasma reverses direction. A plasma hole remains after the positive and negative ions have mutually neutralized. The E x B gradient drift instability produces irregularities on the upwind edge of the hole.

  6. Mesospheric gravity waves and ionospheric plasma bubbles observed during the COPEX campaign

    NASA Astrophysics Data System (ADS)

    Paulino, I.; Takahashi, H.; Medeiros, A. F.; Wrasse, C. M.; Buriti, R. A.; Sobral, J. H. A.; Gobbi, D.

    2011-07-01

    During the Conjugate Point Experiment (COPEX) campaign performed at Boa Vista (2.80∘N;60.70∘W, dip angle21.7∘N) from October to December 2002, 15 medium-scale gravity waves in the OHNIR airglow images were observed. Using a Keogram image analysis, we estimate their parameters. Most of the waves propagate to Northwest, indicating that their main sources are Southeast of Boa Vista. Quasi-simultaneous plasma bubble activities in the OI 630 nm images were observed in seven cases. The distances between the bubble depletions have a linear relationship with the wavelengths of the gravity waves observed in the mesosphere, which suggests a direct contribution of the mesospheric medium-scale gravity waves in seeding the equatorial plasma bubbles.

  7. On the dynamo generation of flux ropes in the Venus ionosphere

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Elphic, R. C.

    1985-01-01

    Small scale (≡10 km) magnetic field structures or "flux ropes" observed in the ionosphere of Venus can be interpreted as the result of a kinematic dynamo process acting on weak seed fields. The seed fields result from the prevailing downward convection of magnetic flux from the vicinity of the ionopause, while small scale fluctuations in the velocity of the ionospheric plasma, which can be caused by collisional coupling to gravity waves in the neutral atmosphere, provide the mechanism by which the field is twisted and redistributed into features of similar scale. This mechanism naturally explains some of the average properties of flux ropes such as the variation of their characteristics with altitude and solar zenith angle. It also elucidates the relationship between the large scale and small scale ionospheric magnetic fields.

  8. Observations of small- to large-scale ionospheric irregularities associated with plasma bubbles with a transequatorial HF propagation experiment and spaced GPS receivers

    NASA Astrophysics Data System (ADS)

    Saito, Susumu; Maruyama, Takashi; Ishii, Mamoru; Kubota, Minoru; Ma, Guanyi; Chen, Yanhong; Li, Jinghua; Ha Duyen, Chau; Le Truong, Thanh

    2008-12-01

    The results from simultaneous observations of the nighttime transequatorial propagation (TEP) of HF radio waves between Australia and Japan and the GPS scintillation measurements in south China and Vietnam are presented in this paper. The results showed that there was good correspondence between the nighttime eastward traveling off-great circle propagation (OGCP) of broadcasting waves of Radio Australia from Shepparton, Australia, measured at Oarai, Japan, and the scintillations in GPS radio waves at Hainan, China. This shows that the nighttime eastward traveling OGCP in HF TEP is caused by a large-scale ionospheric structure associated with a plasma bubble. The zonal drift velocities of the large-scale ionospheric structure estimated by the change in the direction of arrival of the OGCP were similar to those of the small-scale irregularities associated with plasma bubbles measured by the GPS scintillation spaced-receiver technique. Our results show that the HF TEP measurement is quite useful for monitoring the plasma bubble occurrence over a wide area and for forecasting the arrival of the plasma bubble at places located to the east of it.

  9. Effects of electrical coupling on equatorial ionospheric plasma motions: When is the F region a dominant driver in the low-latitude dynamo

    SciTech Connect

    Crain, D.J. ); Heelis, R.A. ); Bailey, G.J. )

    1993-04-01

    The authors address the role of the conductivity of the F region on the observed plasma drift and dynamo motion in the equatorial ionosphere. It has been known for a long time that neutral winds in both the E and F regions can have a major impact on electric fields in these regions, which in turn are responsible for plasma drifts seen there. The authors authors argue that the F region conductivity is important not only to the generation of current in the F region, but to providing closure to currents generated in other regions. The orientation of the neutral winds in the E and F regions relative to the magnetic field plays a role in their impact on electric field generation. They conclude that the zonal F region wind (ionospheric, above [approximately] 150 km) has a major impact on electric fields and plasma drifts in the equatorial region at altitudes from 400 to 800 km, for all local times and solar activities. They argue that it may be incorrect to decouple the E and F regions too strongly, which can overemphasize the role of E region zonal winds. It may be more important to correlate the local magnetic field line measurements in modeling low and mid latitude plasma drift and current phenomena.

  10. Semiannual and solar activity variations of daytime plasma observed by DEMETER in the ionosphere-plasmasphere transition region

    NASA Astrophysics Data System (ADS)

    Li, L. Y.; Cao, J. B.; Yang, J. Y.; Berthelier, J. J.; Lebreton, J.-P.

    2015-12-01

    Using the plasma data of Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite and the NRLMSISE-00 atmospheric model, we examined the semiannual and solar activity variations of the daytime plasma and neutral composition densities in the ionosphere-plasmasphere transition region (~670-710 km). The results demonstrate that the semiannually latitudinal variation of the daytime oxygen ions (O+) is basically controlled by that of neutral atomic oxygen (O), whereas the latitude distributions of the helium and hydrogen ions (He+ and H+) do not fully depend on the neutral atomic helium (He) and hydrogen (H). The summer enhancement of the heavy oxygen ions is consistent with the neutral O enhancement in the summer hemisphere, and the oxygen ion density has significantly the summer-dense and winter-tenuous hemispheric asymmetry with respect to the dip equator. Although the winter enhancements of the lighter He+ and H+ ions are also associated with the neutral He and H enhancements in the winter hemisphere, the high-density light ions (He+ and H+) and electrons (e-) mainly appear at the low and middle magnetic latitudes (|λ| < 50°). The equatorial accumulations of the light plasma species indicate that the light charged particles (He+, H+, and e-) are easily transported by some equatorward forces (e.g., the magnetic mirror force and centrifugal force). The frequent Coulomb collisions between the charged particles probably lead to the particle trappings at different latitudes. Moreover, the neutral composition densities also influence their ion concentrations during different solar activities. From the low-F10.7 year (2007-2008) to the high-F10.7 year (2004-2005), the daytime oxygen ions and electrons increase with the increasing neutral atomic oxygen, whereas the daytime hydrogen ions tend to decrease with the decreasing neutral atomic hydrogen. The helium ion density has no obvious solar activity variation, suggesting that the

  11. The role of the zonal ExB plasma drift in the low latitude ionosphere at solar minimum and maximum near equinox

    NASA Astrophysics Data System (ADS)

    Pavlov, Anatoli

    The F2-layer peak density, NmF2, and peak altitude, hmF2, which were observed by 12 ionospheric sounders during the geomagnetically quiet time periods at solar minimum (20 September 1964) and maximum (12-13 April 1958) are compared with those calculated by the threedimensional time-dependent theoretical model of the Earth's low and middle latitude ionosphere and plasmasphere. Major features of the data are reproduced by the model. The changes in NmF2 due to the zonal E ×B plasma drift are found to be inessential by day. It is shown that the model, which does not take into account the zonal E ×B plasma drift, underestimates night-time NmF2 up to the maximum factors of 2 (solar minimum) and 2.3 (solar maximum) at low geomagnetic latitudes. The night-time increase of NmF2 caused by the zonal E ×B plasma drift is less pronounced at -20° and 20° geomagnetic latitudes in comparison with that between -10° and 10° geomagnetic latitude. The longitude dependence of the calculated nighttime low latitude influence of the zonal E ×B plasma drift on NmF2 is explained in terms of the longitudinal asymmetry in B (the eccentric magnetic dipole is displaced from the Earth's center and the Earth's eccentric tilted magnetic dipole moment is inclined with respect to the Earth's rotational axis), and the variations of the wind induced plasma drift and the meridional E ×B plasma drift in geomagnetic longitude. The difference between the calculated value of hmF2 and that obtained when the zonal E ×B drift is omitted is essential by night and is not exceeding 17 km in the low latitude ionosphere. The model calculations show that over the geomagnetic equator the zonal E ×B plasma drift produces the increase in the electron density up to the maximum factors of 1.5 and 1.3 (solar minimum) and 2 and 1.6 (solar maximum) at 700 km and 1000 km altitude, respectively, and this increase is not significant above about 1500 km. The maximum effects of the zonal E ×B plasma drift on the

  12. Dissociative Recombination of FeO(+) with Electrons: Implications for Plasma Layers in the Ionosphere.

    PubMed

    Bones, D L; Plane, J M C; Feng, W

    2016-03-10

    The dissociative recombination (DR) of FeO(+) ions with electrons has been studied in a flowing afterglow reactor. FeO(+) was generated by the pulsed laser ablation of a solid Fe target, and then entrained in an Ar(+) ion/electron plasma where the absolute electron density was measured using a Langmuir probe. A kinetic model describing gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data, yielding a DR rate coefficient at 298 K of k(FeO(+) + e(-)) = (5.5 ± 1.0) × 10(-7) cm(3) molecule(-1) s(-1), where the quoted uncertainty is at the 2σ level. Fe(+) ions in the lower thermosphere are oxidized by O3 to FeO(+), and this DR reaction is shown to provide a more important route for neutralizing Fe(+) below 110 km than the radiative/dielectronic recombination of Fe(+) with electrons. The experimental system was first validated by measuring two other DR reaction rate coefficients: k(O2(+) + e(-)) = (2.0 ± 0.4) × 10(-7) and k(N2O(+) + e(-)) = (3.3 ± 0.8) × 10(-7) cm(3) molecule(-1) s(-1), which are in good agreement with the recent literature. PMID:26154158

  13. Waves generated in the vicinity of an argon plasma gun in the ionosphere

    NASA Technical Reports Server (NTRS)

    Cahill, L. J., Jr.; Arnoldy, R. L.; Lysak, R. L.; Peria, W.; Lynch, K. A.

    1993-01-01

    Wave and particle observations were made in the close vicinity of an argon plasma gun carned to over 600 km altitude on a sounding rocket. The gun was carned on a subpayload, separated from the main payload early in the flight. Twelve-second argon ion ejections were energized alternately with a peak energy of 100 or 200 eV. They produced waves, with multiple harmonics, in the range of ion cyclotron waves, 10 to 1000 Hz at rocket altitudes. Many of these waves could not be identified as corresponding to the cyclotron frequencies of any of the ions, argon or ambient, known to be present. In addition, the wave frequencies were observed to rise and fall and to change abruptly during a 12-s gun operation. The wave amplitudes, near a few hundred Hertz, were of the order of O. 1 V/m. Some of the waves may be ion-ion hybrid waves. Changes in ion populations were observed at the main payload and at the subpayload during gun operations. A gun-related, field-aligned, electron population also appeared.

  14. Global equatorial ionospheric vertical plasma drifts measured by the AE-E satellite

    SciTech Connect

    Fejer, B.G.; Paula, E.R. de l Heelis, R.A.

    1995-04-01

    Ion drift meter observations from the Atmospheric Explorer E satellite during the period of January 1977 to December 1979 are used to study the dependence of equatorial (dip latitudes {le}7.5{degrees}) F region vertical plasma drifts (east-west electric fields) on solar activity, season, and longitude. The satellite-observed ion drifts show large day-to-day and seasonal variations. Solar cycle effects are most pronounced near the dusk sector with a large increase of the prereversal velocity enhancement from solar minimum to maximum. The diurnal, seasonal, and solar cycle dependence of the longitudinally averaged drifts are consistent with results from the Jicamarca radar except near the June solstice when the AE-E nightime downward velocities are significantly smaller than those observed by the radar. Pronounced presunrise downward drift enhancements are often observed over a large longitudinal range but not in the Peruvian equatorial region. The satellite data indicate that longitudinal variations are largest near the June solstice, particularly near dawn and dusk but are virtually absent during equinox. The longitudinal dependence of the AE-E vertical drifts is consistent with results from ionosonde data. These measurements were also used to develop a description of equatorial F region vertical drifts in four longitudinal sectors. 17 refs., 7 figs.

  15. Radar soundings of the ionosphere of Mars.

    PubMed

    Gurnett, D A; Kirchner, D L; Huff, R L; Morgan, D D; Persoon, A M; Averkamp, T F; Duru, F; Nielsen, E; Safaeinili, A; Plaut, J J; Picardi, G

    2005-12-23

    We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types of ionospheric echoes are observed, ranging from vertical echoes caused by specular reflection from the horizontally stratified ionosphere to a wide variety of oblique and diffuse echoes. The oblique echoes are believed to arise mainly from ionospheric structures associated with the complex crustal magnetic fields of Mars. Echoes at the electron plasma frequency and the cyclotron period also provide measurements of the local electron density and magnetic field strength.

  16. Kinetic and thermodynamic properties of a convecting plasma in a two-dimensional dipole field

    NASA Technical Reports Server (NTRS)

    Huang, T. S.; Birmingham, T. J.

    1994-01-01

    Charged particle guiding center motion is considered in the magnetic field of a two-dimensional ('line') dipole on which is superimposed a small, static, perpendicular electric field. The parallel equation of motion is that of a simple harmonic oscillator for cos theta, the cosine of magnetic colatitude theta. Equations for the perpendicular electric and magnetic drifts are derived as well as their bounce-averaged forms. The latter are solved to yield a bounce-averaged guiding center trajectory, which is the same as that obtained from conversation of magnetic moment mu, longitudinal invariant J, and total (kinetic plus electrostatic) energy K. The algebraic simplicity of the trajectory equations is also manifest in the forms of the invariants. An interesting result is that guiding centers drift in such a way that they preserve the values of their equatorial pitch angles and (equivalently) mirror latitudes. The most general Maxwellian form of the equilibrium one-particle distribution function f is constructed from the invariants, and spatially varying density and pressure moments, parallel and perpendicular to the magnetic field, are identified. Much of the paper deals with the more restricted problem in which f is specified as a bi-Maxwellian over a straight line of finite length in the equatorial plane of the dipole and perpendicular to field lines. This might be thought of as specifying a cross-tail ion injection source; our formalism then describes the subsequent spatial development. The distribution away from the source is a scaled bi-Maxwellian but one that is cut off at large and small kinetic energies, which depend on position. Density and pressure components are reduced from the values they would have if the total content of individual flux tubes convected intact. The equatorial and meridional variations of density and pressure components are examined and compared systematically for the isotropic and highly anisotropic situations. There appears to be little

  17. Momentum, heat, and neutral mass transport in convective atmospheric pressure plasma-liquid systems and implications for aqueous targets

    NASA Astrophysics Data System (ADS)

    Lindsay, Alexander; Anderson, Carly; Slikboer, Elmar; Shannon, Steven; Graves, David

    2015-10-01

    There is a growing interest in the study of plasma-liquid interactions with application to biomedicine, chemical disinfection, agriculture, and other fields. This work models the momentum, heat, and neutral species mass transfer between gas and aqueous phases in the context of a streamer discharge; the qualitative conclusions are generally applicable to plasma-liquid systems. The problem domain is discretized using the finite element method. The most interesting and relevant model result for application purposes is the steep gradients in reactive species at the interface. At the center of where the reactive gas stream impinges on the water surface, the aqueous concentrations of OH and ONOOH decrease by roughly 9 and 4 orders of magnitude respectively within 50 μ m of the interface. Recognizing the limited penetration of reactive plasma species into the aqueous phase is critical to discussions about the therapeutic mechanisms for direct plasma treatment of biological solutions. Other interesting results from this study include the presence of a 10 K temperature drop in the gas boundary layer adjacent to the interface that arises from convective cooling. Though the temperature magnitudes may vary among atmospheric discharge types (different amounts of plasma-gas heating), this relative difference between gas and liquid bulk temperatures is expected to be present for any system in which convection is significant. Accounting for the resulting difference between gas and liquid bulk temperatures has a significant impact on reaction kinetics; factor of two changes in terminal aqueous species concentrations like H2O2, NO2- , and NO3- are observed in this study if the effect of evaporative cooling is not included.

  18. Venus ionosphere - Photochemical and thermal diffusion control of ion composition

    NASA Technical Reports Server (NTRS)

    Bauer, S. J.; Hartle, R. E.; Taylor, H. A., Jr.; Donahue, T. M.

    1979-01-01

    The major photochemical sources and sinks for ten of the ions measured by the ion mass spectrometer on the Pioneer Venus bus and orbiter spacecraft that are consistent with the neutral gas composition measured on the same spacecraft are identified. The neutral gas temperature (as a function of solar zenith angle) derived from measured ion distributions in photochemical equilibrium is given. Above 200 kilometers, the altitude behavior of ions is generally controlled by plasma diffusion, with important modifications for minor ions due to thermal diffusion resulting from the observed gradients of plasma temperatures. The dayside equilibrium distributions of ions are sometimes perturbed by plasma convection, while lateral transport of ions from the dayside seems to be a major source of the nightside ionosphere.

  19. A two-dimensional kinematic dynamo model of the ionospheric magnetic field at Venus

    NASA Technical Reports Server (NTRS)

    Cravens, T. E.; Wu, D.; Shinagawa, H.

    1990-01-01

    The results of a high-resolution, two-dimensional, time dependent, kinematic dynamo model of the ionospheric magnetic field of Venus are presented. Various one-dimensional models are considered and the two-dimensional model is then detailed. In this model, the two-dimensional magnetic induction equation, the magnetic diffusion-convection equation, is numerically solved using specified plasma velocities. Origins of the vertical velocity profile and of the horizontal velocities are discussed. It is argued that the basic features of the vertical magnetic field profile remain unaltered by horizontal flow effects and also that horizontal plasma flow can strongly affect the magnetic field for altitudes above 300 km.

  20. A Dynamic Coupled Magnetosphere-Ionosphere-Ring Current Model

    NASA Astrophysics Data System (ADS)

    Pembroke, Asher

    In this thesis we describe a coupled model of Earth's magnetosphere that consists of the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamics (MHD) simulation, the MIX ionosphere solver and the Rice Convection Model (RCM). We report some results of the coupled model using idealized inputs and model parameters. The algorithmic and physical components of the model are described, including the transfer of magnetic field information and plasma boundary conditions to the RCM and the return of ring current plasma properties to the LFM. Crucial aspects of the coupling include the restriction of RCM to regions where field-line averaged plasma-beta ¡=1, the use of a plasmasphere model, and the MIX ionosphere model. Compared to stand-alone MHD, the coupled model produces a substantial increase in ring current pressure and reduction of the magnetic field near the Earth. In the ionosphere, stronger region-1 and region-2 Birkeland currents are seen in the coupled model but with no significant change in the cross polar cap potential drop, while the region-2 currents shielded the low-latitude convection potential. In addition, oscillations in the magnetic field are produced at geosynchronous orbit with the coupled code. The diagnostics of entropy and mass content indicate that these oscillations are associated with low-entropy flow channels moving in from the tail and may be related to bursty bulk flows and bubbles seen in observations. As with most complex numerical models, there is the ongoing challenge of untangling numerical artifacts and physics, and we find that while there is still much room for improvement, the results presented here are encouraging. Finally, we introduce several new methods for magnetospheric visualization and analysis, including a fluid-spatial volume for RCM and a field-aligned analysis mesh for the LFM. The latter allows us to construct novel visualizations of flux tubes, drift surfaces, topological boundaries, and bursty-bulk flows.

  1. Innovative development and application of models for weakly ionized ionospheric plasmas. Final report, 15 May 1990-30 November 1993

    SciTech Connect

    Eccles, J.V.; Hingst, J.; Armstrong, R.

    1993-11-01

    Artificial modifications of the ionosphere through chemical releases and ionospheric heating experiments are examined with models of chemistry and transport to advance understanding of ion chemistry of the upper atmosphere. The specific releases investigated were the SF6 released of the CRRES-at-Kwajalein rocket campaign and the CO2 releases of the Red Air I program. Both the SF6 and CO2 releases experienced freezing or clustering of the molecules. This must be accounted for in the composition and airglow observations. In addition, HF heating effects in the E and F region were examined through modeling of energy deposition and resulting chemistry. NO sub x production in a HF ionospheric heater beam is estimated and compared with natural sources of NO sub x. Global effects of HF operation are very small but the local effects can be large enough to permit observable modulation to this environment.

  2. Multi-instrument investigation of troposphere-ionosphere coupling through gravity waves and the role of gravity waves in the formation of equatorial plasma bubbles (EPBs)

    NASA Astrophysics Data System (ADS)

    Sivakandan, Mani; Patra, Amit; Sripathi, Samireddipelle; Thokuluwa, Ramkumar; Paulino, Igo; Taori, Alok; Kandula, Niranjan

    2016-07-01

    Equatorial plasma bubble (EPB) occurs in the equatorial ionosphere in pre-mid night (most of the time) as well as post-midnight (rarely) hours. The generation of EPBs by Rayleigh-Taylor Instability (RTI) due to seeding of gravity wave perturbation (polarization electric field) have well been explained theoretically by several authors but experimental evidence supporting this hypothesis is very limited. Using co-located observations from Gadanki (13.5oN, 79.2o E) using an all sky airglow imager and Gadanki Ionospheric Radar Interferometer (GIRI) and Ionosonde observations from Tirunelveli (8.7o N, 77.8o E), we investigate the role of gravity waves in the generation EPB during geomagnetic quiet conditions. To avoid any changes occurring in the background ionosphere owing to the large scale features (e.g., seasonal variation), we use four consecutive nights (03-06, February, 2014). Out of these four nights on two nights we have noted very strong plasma depletions in the OI 630 nm airglow emission and radar plumes. We analyse data to identify cases where, 1) EPBs occurred with large amplitudes of mesospheric gravity waves, 2) Occurrence of EPBs without large amplitudes of mesospheric gravity waves, and 3) identifiable mesospheric gravity waves without occurrence of EPBs. In order to calculate the mesospheric gravity wave parameter we used mesospheric OH airglow emission imager data, to identify their propagation to the E-region, we used E-region observations made using the MST radar which resembled the gravity wave signatures. Together with these, by using ray tracing techniques, we have identified the source region of the noted gravity wave events also. These results are discussed in detail in the present study.

  3. Polar BEAR ionospheric experiments - a pre-launch overview. Technical report, 1 March-31 October 1985

    SciTech Connect

    Fremouw, E.J.

    1986-05-09

    Polar BEAR (Polar BEacon and Auroral Research) will carry three ionospheric experiments: (1) a beacon functionally identical to that on HiLat, (2) a three-axis vector magnetometer for detecting the satellite's attitude, and (3) an improved imager, the Auroral/Ionospheric Remote Sensor (AIRS). In addition to providing images of the aurorae and airglow at four visual and vacuum-ultraviolet wavelengths, AIRS will function as an ultraviolet spectrophotometer. Using AIRS in its imaging mode and receiving stations it will be possible to obtain images of essentially the entire auroral oval in broad daylight as well as in darkness. Polar BEAR is scheduled for launch into a nearly circular orbit near 1000-km altitude and 82 inclination. That orbit will afford a broad view for AIRS and many opportunities for coordinated observations of (1) scintillation using the beacons on both HiLat and Polar BEAR, (2) major current systems flowing between the ionosphere and magnetosphere using the magnetometers on both satellites, and (3) energetic electron precipitation and ambient plasma convection at 800 km altitude as recorded with HiLat's electron spectrometer and thermal-plasma monitor. These observations should contribute to further understanding of plasma instrumental to the development of density irregularities in the highly dynamic high-latitude ionosphere.

  4. Beam-plasma generators of stochastic microwave oscillations used for plasma heating in fusion and plasma-chemistry devices and ionospheric investigations

    NASA Astrophysics Data System (ADS)

    Mitin, Leonid A.; Perevodchikov, Vladimir I.; Shapiro, A. L.; Zavjalov, M. A.; Bliokh, Yury P.; Fainberg, Ya. B.

    1996-10-01

    The results of theoretical and experimental investigations of generator of stochastic microwave power based on beam- plasma inertial feedback amplifier is discussed to use stochastic oscillation for heating of plasma. The efficiency of heating of plasma in the region of low-frequency resonance in the geometry of `Tokomak' is considered theoretically. It is shown, that the temp of heating is proportional the power multiplied by spectra width of noiselike signal.

  5. A method for determining the drift velocity of plasma depletions in the equatorial ionosphere using far-ultraviolet spacecraft observations: initial results

    NASA Astrophysics Data System (ADS)

    England, S. L.; Immel, T. J.; Park, S. H.; Frey, H. U.; Mende, S. B.

    2007-12-01

    The Far-Ultraviolet Imager (IMAGE-FUV) on-board the NASA IMAGE satellite has been used to observe plasma depletions in the nightside equatorial ionosphere. Observations from periods around spacecraft apogee, during which equatorial regions are visible for several hours, have allowed the velocity of these plasma depletions to be determined. A new method for determining the velocity of these depletions using an image analysis technique, Tracking Of Airglow Depletions (TOAD), has been developed. TOAD allows the objective identification and tracking of depletions. The automation of this process has also allowed for the tracking of a greater number of depletions than previously achieved without requiring any human input, which shows that TOAD is suitable for use with large data sets and for future routine monitoring of the ionosphere from space. Furthermore, this allows the drift velocities of each depletion to be determined as a function of magnetic latitude as well as local time. Previous ground-based airglow observations from a small number of locations have indicated that the drift velocities of depletions may vary rapidly with magnetic latitude. Here we shall present the first results from TOAD of this shear in drift velocities from our global sample of depletion drift velocities.

  6. Observations of filamentary field-aligned current coupling between the magnetospheric boundary layer and the ionosphere

    NASA Technical Reports Server (NTRS)

    Clauer, C. R.; Mchenry, M. A.; Friis-Christensen, E.

    1990-01-01

    A distinct class of dayside high-latitude magnetic pulsations can be identified from the spatial characteristics of the disturbance field. These pulsations exhibit traveling radial patterns such as would result from moving filaments of field-aligned current interacting with the ionosphere to produce cells of Hall current and vortexlike plasma flow. Time intervals containing a series of continuous multiple vortices are investigated here. The vortices occur on the boundary between sunward and antisunward ionospheric plasma convection. Low altitude DMSP satellite particle measurements indicate that the vortices are on magnetic field lines which map to the inner edge of the magnetospheric low latitude boundary layer. No repetitive solar wind disturbance (e.g., pressure variations) appears to be associated with the events, suggesting that the vortices are related to a local magnetospheric instability. No strong correlation between interplanetary field conditions and the detection of vortices is found.

  7. A comparison of the effects of initializing different thermosphere-ionosphere model fields on storm time plasma density forecasts

    NASA Astrophysics Data System (ADS)

    Chartier, Alex T.; Jackson, David R.; Mitchell, Cathryn N.

    2013-11-01

    assimilation has been used successfully for real-time ionospheric specification, but it has not yet proved advantageous for forecasting. The most challenging and important ionospheric events to forecast are storms. The work presented here examines the effectiveness of data assimilation in a storm situation, where the initial conditions are known and the model is considered to be correct but the external solar and geomagnetic drivers are poorly specified. The aim is to determine whether data assimilation could be used to improve storm time forecast accuracy. The results show that, in the case of the storm of Halloween 2003, changes made to the model's initial thermospheric conditions improve electron density forecasts by at least 10% for 18 h, while changes to ionospheric fields alone result in >10% forecast accuracy improvement for less than 4 h. Further examination shows that the neutral composition is especially important to the accuracy of ionospheric electron density forecasts. Updating the neutral composition gives almost all the benefits of updating the complete thermospheric state. A comparison with real, globally distributed observations of vertical total electron content confirms that updating the thermospheric composition can improve forecast accuracy.

  8. Magnetospheric convection strength inferred from inner edge of the electron plasma sheet and its relation to the polar cap potential drop

    NASA Astrophysics Data System (ADS)

    Jiang, F.; Kivelson, M. G.; Walker, R. J.; Khurana, K. K.; Angelopoulos, V.

    2010-12-01

    The sharp inner edge of the nightside electron plasma sheet observed by the THEMIS spacecraft is shown to provide a measure of the effective convection strength that transports plasma sheet plasma into the inner magnetosphere. The effective convection strength is characterized by the difference of potential between the magnetopause terminators at dawn and at dusk. We have surveyed inner boundary crossings of the electron plasma sheet measured by three THEMIS probes on orbits from Nov. 2007 to Apr. 2009. The values of the convection electric potential are inferred from the locations of the inner edge for different energy channels using a steady-state drift boundary model with a dipole magnetic field and a Volland-Stern electric field. When plotted against the solar wind electric field ( ), the convection electric potential is found to have a quasi-linear relationship with the driving solar wind electric field for the range of values tested (meaningful statistics only for Esw < 1.5 mV/m). Reasonably good agreement is found between the convection electric potential and the polar-cap potential drop calculated from model of Boyle et al. [1997] when the degree of shielding in the Volland-Stern potential is selected as gamma=1.5.

  9. Persistent Longitudinal Variations of Plasma Density and DC Electric Fields in the Low Latitude Ionosphere Observed with Probes on the C/NOFS Satellite

    NASA Technical Reports Server (NTRS)

    Pfaff, R.; Freudenreich, H.; Klenzing, J.; Rowland, D.; Liebrecht, C.; Bromund, K.; Roddy, P.

    2010-01-01

    Continuous measurements using in situ probes on consecutive orbits of the C/N0FS satellite reveal that the plasma density is persistently organized by longitude, in both day and night conditions and at all locations within the satellite orbit, defined by its perigee and apogee of 401 km and 867 km, respectively, and its inclination of 13 degrees. Typical variations are a factor of 2 or 3 compared to mean values. Furthermore, simultaneous observations of DC electric fields and their associated E x B drifts in the low latitude ionosphere also reveal that their amplitudes are also strongly organized by longitude in a similar fashion. The drift variations with longitude are particularly pronounced in the meridional component perpendicular to the magnetic field although they are also present in the zonal component as well. The longitudes of the peak meridional drift and density values are significantly out of phase with respect to each other. Time constants for the plasma accumulation at higher altitudes with respect to the vertical drift velocity must be taken into account in order to properly interpret the detailed comparisons of the phase relationship of the plasma density and plasma velocity variations. Although for a given period corresponding to that of several days, typically one longitude region dominates the structuring of the plasma density and plasma drift data, there is also evidence for variations organized about multiple longitudes at the same time. Statistical averages will be shown that suggest a tidal "wave 4" structuring is present in both the plasma drift and plasma density data. We interpret the apparent association of the modulation of the E x B drifts with longitude as well as that of the ambient plasma density as a manifestation of tidal forces at work in the low latitude upper atmosphere. The observations demonstrate how the high duty cycle of the C/NOFS observations and its unique orbit expose fundamental processes at work in the low latitude

  10. Attribution of ionospheric vertical plasma drift perturbations to large-scale waves and the dependence on solar activity (Invited)

    NASA Astrophysics Data System (ADS)

    Liu, H.; Richmond, A. D.

    2013-12-01

    In this study we quantify the contribution of individual large-scale waves to ionospheric electrodynamics, and examine the dependence of the ionospheric perturbations on solar activity. We focus on migrating diurnal tide (DW1) plus mean winds, migrating semidiurnal tide (SW2), quasi-stationary planetary wave 1 (QSPW1), and nonmigrating semidiurnal westward wave 1 (SW1) under northern winter conditions, when QSPW1 and SW1 are climatologically strong. From TIME-GCM simulations under solar minimum conditions, we calculate equatorial vertical ExB drifts due to mean winds and DW1, SW2, SW1 and QSPW1. In particular, wind components of both SW2 and SW1 become large at mid to high latitudes in the E-region, and kernel functions obtained from numerical experiments reveal that they can significantly affect the equatorial ion drift, likely through modulating the E-region wind dynamo. The most evident changes of total ionospheric vertical drift when solar activity is increased are seen around dawn and dusk, reflecting the more dominant role of large F-region Pedersen conductivity and of the F-region dynamo under high solar activity. Therefore, the lower atmosphere driving of the ionospheric variability is more evident under solar minimum conditions, not only because variability is more identifiable in a quieter background, but also because the E-region wind dynamo is more significant. These numerical experiments also demonstrate that the amplitudes, phases and latitudinal and vertical structures of large-scale waves are important in quantifying the ionospheric responses.

  11. Plasma transport in the magnetotail lobes

    NASA Astrophysics Data System (ADS)

    Haaland, S.; Lybekk, B.; Svenes, K.; Pedersen, A.; Förster, M.; Vaith, H.; Torbert, R.

    2009-09-01

    The Earth's magnetosphere is populated by particles originating from the solar wind and the terrestrial ionosphere. A substantial fraction of the plasma from these sources are convected through the magnetotail lobes. In this paper, we present a statistical study of convective plasma transport through the Earth's magnetotail lobes for various geomagnetic conditions. The results are based on a combination of density measurements from the Electric Field and Waves Experiment (EFW) and convection velocities from the Electron Drift Instrument (EDI) on board the Cluster spacecraft. The results show that variations in the plasma flow is primarily attributed to changes in the convection velocity, whereas the plasma density remains fairly constant and shows little correlation with geomagnetic activity. During disturbed conditions there is also an increased abundance of heavier ions, which combined with enhanced convection, cause an accentuation of the mass flow. The convective transport is much slower than the field aligned transport. A substantial amount of plasma therefore escape downtail without ever reaching the central plasma sheet.

  12. Response of Ionosphere to the Tropospheric disturbances

    NASA Astrophysics Data System (ADS)

    Maurya, A. K.; Dube, A.; Singh, R.; Cohen, M.

    2015-12-01

    The aim of the present work is to find out response of the ionosphere to the various cases of tropical cyclones. The main process involved is suggested through Atmospheric Gravity waves (AGWs) originating from strong convective systems, propagating upward upto the ionospheric heights and perturbing ionospheric parameters (Bishop et al., 2006). We have used ground and satellite data to extract cyclone induced perturbations at different ionospheric heights along with the various parameters of AGWs during cyclones and associated thunderstorm. The initial results suggest that there is increase in total electron content of the ionosphere with wave like signatures in ionosphere. The satellite observation in optical band shows presence of concentric gravity wave pattern associated with troposphere disturbances with horizontal wavelength of ~50-200km and periods ranging from hours to days. The ground based Very Low Frequency (VLF) measurement shows fluctuations in VLF navigational transmitter signal passing over the region of disturbance. The lightning data from GLD360 lightning network shows intense activity associated with cyclones and increase in lightning peak current and energy during main phase of cyclones which seems to be sufficient enough to derive ionospheric disturbances in the ionosphere. This multi-instrument analysis provide detail information of the three dimensional structure of cyclone and their effect at different altitudes of the ionosphere in the Indian subcontinent.

  13. Plasma structuring in the polar cap

    SciTech Connect

    Basu, S.; Basu, S.; Weber, E.J.; Bishop, G.J.

    1990-01-01

    Propagation experiments providing scintillation, total electron content and drift data in the field of view of an all-sky imager near the magnetic polar in Greenland are utilized to investigate the manner in which ionospheric plasma becomes structured within the polar cap. It is found that under IMF Bz southward conditions, large scale ionization patches which are convected through the dayside cusp into the polar cap get continually structured. The structuring occurs through the ExB gradient drift instability process which operates through an interaction between the antisunward plasma convection in the neutral rest frame and large scale plasma density gradients that exist at the edges of the ionization patches. It is shown that with the increase of solar activity the strength of the irregularities integrated through the ionosphere is greatly increased. Under the IMF Bz northward conditions, the plasma structuring occurs around the polar cap arcs in the presence of inhomogeneous electric field or disordered plasma convection. In that case, the irregularity generation is caused by the competing processes of non-linear Kelvin-Helmholtz instability driven by sheared plasma flows and the gradient drift instability process which operates in the presence of dawn-dusk motion of arc structures. The integrated strength of this class of irregularities also exhibits marked increase with increasing solar activity presumably because the ambient plasma density over the polar cap is enhanced.

  14. Investigation of methods for improving models of ionospheric plasma-density irregularities and radio-frequency scintillation. Technical report

    SciTech Connect

    Secan, J.A.; Bussey, R.M.

    1993-11-01

    Many modern military systems used for communications, command and control, navigation, and surveillance depend on reliable and relatively noise-free transmission of radiowave signals through the earth's ionosphere. Small-scale irregularities in the ionospheric density can cause severe distortion, known as radiowave scintillation, of both the amplitude and phase of these signals. The WBMOD computer program can be used to estimate these effects on a wide range of systems. The objective of this study is to investigate improvements to the WBMOD model based on extensive data sets covering both the equatorial and high-latitude regimes. This report summarizes the work completed during the second year, which include completion of the new models for the equatorial region and initial development of models for the high latitude (auroral and polar cap) region.

  15. Origin of density enhancements in the winter polar-cap ionosphere

    SciTech Connect

    Anderson, D.N.; Buchau, J.; Heelis, R.A.

    1987-05-07

    Coherent and incoherent ground-based radar measurements of the winter polar cap ionosphere at Thule and Sondrestrom, Greenland, have established the existence of patches of enhanced ionization that drift across the polar cap in an antisunward, noon-midnight direction. Associated with these patches is strong radio scintillation activity which severely disrupts ground-to-satellite communication systems and interferes with the operation of space surveillance radar at high latitudes. Several recent studies have shown that the source of enhanced ionization is the sunlit sub-cusp ionosphere rather than production by precipitating energetic particles. This problem is studied by solving the time-dependent plasma continuity equation including production by solar ultraviolet radiation, loss through charge exchange and transport by diffusion and convection E X B drifts. Time and spatially varying, horizontal E X B drift patterns are imposed and subsequent ionospheric responses are calculated to determine enhanced plasma densities. In the dark polar cap could result from extended transit of relevant flux tubes through regions of significant solar production. A density enhancement in NMAX from 70,000 to 500,000 el/cu cm occurs at Thule when a time-varying convection pattern is included in the simulation. The patch of ionization is generated when an initial convection pattern characterized by an 80-kV crosstail potential and a 12/degree/ polar cap radius is abruptly changed to a 100-kV crosstail potential and a 15/degree/ polar-cap radius. The horizontal extent of the patch is related to the length of time the new convection pattern remains turned-on.

  16. Saturn's ionosphere and plasmasphere

    NASA Astrophysics Data System (ADS)

    Moore, Luke Edward

    2008-01-01

    ionospheric plasma depletions. The first calculations of the time-dependent effect of attenuation of sunlight by Saturn's rings indicate that they cause large latitudinal gradients within the ionosphere, and may provide radio frequency windows through which atmospheric lightning is observed. Warm plasma temperatures are predicted in Saturn's upper atmosphere, with a strong dawn/dusk asymmetry and a large diurnal variation.

  17. New evidence of dayside plasma transportation over the polar cap to the prevailing dawn sector in the polar upper atmosphere for solar-maximum winter

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Gao; Zhang, Bei-Chen; Fang, Han-Xian; Kamide, Y.; Li, Chong-Yin; Liu, Jun-Ming; Zhang, Shun-Rong; Liu, Rui-Yuan; Zhang, Qing-He; Hu, Hong-Qiao

    2016-06-01

    It is well known that owing to the transport of high-density sunlit plasma from dayside to nightside primarily by convection, polar cap tongue of ionization (TOI), polar cap patches, and blobs are common features in the polar ionosphere. The steep density gradients at the edges of these structures lead to severe problems in applications involving radio waves traversing the ionosphere. To better understand the evolution of TOI/patches/blobs, it is essential to examine how the transported sunlit plasma is distributed. Through averaging the hourly total electron content in solar-maximum winter, we present complete distribution of polar ionospheric plasma and find that the dayside plasma can be transported through cusp, over polar cap, and eventually to the prevailing dawnside, showing asymmetric distribution around magnetic midnight. The negative interplanetary magnetic field By or Bz component is favored for the plasma transportation from dayside to the prevailing dawn sector. This provides direct evidence for the plasma source of the dawnside high-density plasma structure. The same corotating convection direction as convection at auroral dawnside is responsible for the prevailing dawn sector transportation. This finding is significant for forecasting TOI/patches/blobs in conducting space weather in the polar ionosphere.

  18. Effect of Precipitating Electrons on Ring Current Energy Content, Ionospheric Conductance, and Thermospheric Properties

    NASA Astrophysics Data System (ADS)

    Chen, M.; Lemon, C. L.; Walterscheid, R. L.; Yoo, B.; Hecht, J. H.; Shprits, Y.; Orlova, K.; Schulz, M.; Evans, J. S.

    2014-12-01

    We investigate how scattering of electrons by waves in the plasma sheet and plasmasphere affects precipitating energy flux distributions during magnetic storms, how the precipitating electrons modify the ionospheric Hall and Pederson conductivity and electric potential, how these processes feedback on magnetospheric particle transport and redistribute the ring current, and how the ionization and energy deposition of precipitating electrons affects thermospheric winds and temperature. Our main approach is to couple simulation models: (1) the magnetically and electrically self-consistent Rice Convection Model - Equilibrium (RCM-E) of the inner magnetosphere, (2) the B3c transport model for electron-proton-hydrogen atom aurora in the ionosphere, and (3) the Thermosphere-Ionsphere-Electrodynamics General Circulation Model (TIEGCM) of the ionosphere and thermosphere. Realistic descriptions of electron pitch-angle diffusion by whistler chorus in the plasma sheet/magnetotail and hiss in the plasmasphere are included in the RCM-E. We use parameterized rates of electron pitch-angle scattering with whistler chorus of Orlova and Shprits [JGR, 2014] that depend on equatorial radial distance, magnetic activity (Kp), and magnetic local time. To study how the precipitating electron energy flux distributions affect ionospheric conductivity and ionospheric electric potential patterns, we have performed a one-way coupling of the RCM-E and ionospheric B3c model. The simulated precipitating electron flux distributions are used to specify the energy flux and particle heating due to precipitating auroral electrons for TIEGCM simulations of the neutral atmosphere. We simulate a storm event and compare simulated quantities with in situ observations.

  19. Two-Dimensional Mappng of the Plasma Density in the Upper Atmosphere with Computerized Ionospheric Tomography (CIT)

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.

    1997-11-01

    Tomographic imaging of the ionosphere is a recently developed technique that uses integrated measurements and computer reconstructions to determine both electron and ion densities. The integral of electron density is obtained from the phase of VHF/UFH radio transmissions from orbiting satellite beacons broadcasting to a chain of receivers on the earth's surface. The integral of oxygen ion densities is determined from optical measurements of extreme ultraviolet (EUV) emissions that are recorded with orbiting spectrometers. Radiative recombination of O^+-ions and electrons yields 91.1 nm and 135.6 nm emissions that are observable at night. During the day, photoionization of atomic oxygen yields 83.4 nm emissions that are scattered by the O^+-ion for illumination of the ionospheric densities. Each type of measurement has unique advantages and limitations. Transmissions of radio waves from satellite to ground have high spatial resolution (10 km or better) but suffer from the lack of horizontal integration paths and the requirement for ground receivers. The EUV optical signals are observable from any direction but they are the strongest when the satellite is scanning the earth's limb. The radio wave phase noise is much less than the EUV photon counting noise. Optical tomography is expected to yield 5 to 20 km vertical resolution and about 50 to 500 km horizontal resolution. The most effective way of mapping the ionosphere is to analyze the combined radio and EUV data using computerized ionospheric tomography (CIT). The radio and EUV techniques provide cross-calibration along co-aligned observation paths and provide missing data in the other regions of the tomographic scans. New ionospheric imaging instruments are scheduled for launch on a number of spacecraft including the NASA sponsored TERRIERS and the DoD sponsored ARGOS satellites. To support these instruments, algorithms are being developed for tomographic reconstructions. These algorithms must accomodate noise in

  20. Ionospheric Current Systems Under Magnetic Cloud Condition

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Rostoker, G.; Sun, W.; Du, A.; Lui, T.

    2005-12-01

    During magnetic clouds the solar wind has properties of low plasma beta, intense magnetic field, smooth north-south (or south-north) magnetic field polarity reversals, and a general absence of Alfven waves and discontinuities. The earth's magnetospheric and ionospheric convection velocities significantly increase during periods of southward IMF within magnetic clouds. At high latitudes, a two-cell convection pattern develops that can be quantitatively described by the DP2 equivalent current system. Under certain circumstances, "sawtooth" events occur featuring quasi-periodic substorm expansion phase activity in which westward electrojets (i.e., equivalent DP1 current) appear in the midnight sector in association with each substorm expansion phase. By studying the April 18, 2002 "sawtooth" event, we show how the DP2 and DP1 current systems develop during a smooth southward IMF interval within the magnetic cloud. With an absence of external triggering, the occurrence of quasi-periodic substorm expansion onsets suggests that this "sawtooth" event may be a result of magnetospheric self-regulation. We also discuss the corresponding energy transfer from the magnetotail where the tail magnetic field intensity is seen to vary quasi-periodically.

  1. C/NOFS Observations of Longitudinal Ionospheric Variability

    NASA Astrophysics Data System (ADS)

    de la Beaujardiere, O.; Huang, C.; Colman, J. J.; Roddy, P.; Dao, E.; Kelley, M. C.; Crowley, G.; Pfaff, R. F.

    2012-12-01

    Launched at a 13 degrees inclination, the Communication/Navigation Outage Forecasting System (C/NOFS) satellite samples all longitudes during each orbit. C/NOFS is thus ideal for studying how the ionospheric ambient density and scintillation-producing irregularities vary with longitude. Irregularities maximize in frequency and amplitude in the America to Africa sector. It has been suggested that waves generated by tropospheric convection propagate upward and launch secondary waves that are responsible for triggering the instability that gives rise to equatorial plasma bubbles. Lightning frequency can be used as a proxy for tropospheric convection regions. We thus examine the possibility that the longitudinal variability is related to the occurrence of lightning, since the frequency of lightning in the equatorial regions is largest in Africa and then South America. We also present simultaneous data from C/NOFS and from the TID Detector Built in Texas (TIDDBIT) system newly installed in Peru. The purpose is to investigate a possible relationship between C/NOFS ionospheric irregularities and the waves observed below the F-peak by TIDDBIT. C/NOFS can also be used to investigate longitudinal changes in the ambient density. For example, as the solar cycle increased, the F-peak height increased. Close to perigee (400 km), C/NOFS was often below the F-peak. Preliminary analysis suggests that the F-peak altitude varies with longitude and is highest in the America to Africa sector.

  2. Physical Processes for Driving Ionospheric Outflows in Global Simulations

    NASA Technical Reports Server (NTRS)

    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.

  3. Computer study of convection of weakly ionized plasma in a nonuniform magnetic field.

    NASA Technical Reports Server (NTRS)

    Shiau, J. N.

    1972-01-01

    A weakly ionized plasma in a strong and nonuniform magnetic field exhibits an instability analogous to the flute instability in a fully ionized plasma. The instability sets in at a critical magnetic field. To study the final state of the plasma after the onset of the instability, the plasma equations are integrated numerically assuming a certain initial spectrum of small disturbances. In the regime studied, numerical results indicate a final steadily oscillating state consisting of a single finite amplitude mode together with a time-independent modification of the original equilibrium. These results agree with the analytic results obtained by Simon in the slightly supercritical regime. As the magnetic field is increased further, the wavelength of the final oscillation becomes nonunique. There exists a subinterval in the unstable wave band. Final stable oscillation with a wavelength in this subinterval can be established if the initial disturbance has a sufficiently strong component at the particular wavelength.

  4. Evidence for Corotating Convection in Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Kivelson, M. G.; Southwood, D. J.; Dougherty, M. K.

    2006-05-01

    Saturn's magnetic field exhibits a high degree of azimuthal symmetry, yet the field and plasma signatures of the magnetosphere are modulated at a period close to that of planetary rotation. How, then, is a clear periodicity imposed on the magnetic field and plasma of the planetary magnetosphere? In this talk, Cassini magnetometer data are used to develop a scenario for the dynamics of the Saturn magnetosphere. The proposal is that mass transport, accomplished in the inner magnetosphere by interchange motion, feeds into the outer magnetosphere where ballooning driven by centrifugal stress leads to outward transport, field reconnection and plasma loss in a favored local time sector; flux is transported inward in other regions. The model is closely related to the concept of corotating convection proposed by Dessler, Hill, and co-workers for Jupiter. The proposed mechanism can be consistent with aspects of the empirical camshaft model introduced by Espinosa et al., 2003 to explain Pioneer and Voyager magnetometer data. Anomalous transport here proposed could originate from a localized ionospheric conductivity anomaly. The resulting cyclic stress modulates the current in the current sheet and can account for its north-south excursions. The convection patterns proposed also imply that corotating, field-aligned currents would be a basic feature of the Saturn system.

  5. Convective transport of highly plasma protein bound drugs facilitates direct penetration into deep tissues after topical application

    PubMed Central

    Dancik, Yuri; Anissimov, Yuri G; Jepps, Owen G; Roberts, Michael S

    2012-01-01

    AIMS To relate the varying dermal, subcutaneous and muscle microdialysate concentrations found in man after topical application to the nature of the drug applied and to the underlying physiology. METHODS We developed a physiologically based pharmacokinetic model in which transport to deeper tissues was determined by tissue diffusion, blood, lymphatic and intersitial flow transport and drug properties. The model was applied to interpret published human microdialysis data, estimated in vitro dermal diffusion and protein binding affinity of drugs that have been previously applied topically in vivo and measured in deep cutaneous tissues over time. RESULTS Deeper tissue microdialysis concentrations for various drugs in vivo vary widely. Here, we show that carriage by the blood to the deeper tissues below topical application sites facilitates the transport of highly plasma protein bound drugs that penetrate the skin, leading to rapid and significant concentrations in those tissues. Hence, the fractional concentration for the highly plasma protein bound diclofenac in deeper tissues is 0.79 times that in a probe 4.5 mm below a superficial probe whereas the corresponding fractional concentration for the poorly protein bound nicotine is 0.02. Their corresponding estimated in vivo lag times for appearance of the drugs in the deeper probes were 1.1 min for diclofenac and 30 min for nicotine. CONCLUSIONS Poorly plasma protein bound drugs are mainly transported to deeper tissues after topical application by tissue diffusion whereas the transport of highly plasma protein bound drugs is additionally facilitated by convective blood, lymphatic and interstitial transport to deep tissues. PMID:21999217

  6. MarsCAT: Mars Array of ionospheric Research Satellites using the CubeSat Ambipolar Thruster

    NASA Astrophysics Data System (ADS)

    Bering, E. A., III; Pinsky, L.; Li, L.; Jackson, D. R.; Chen, J.; Reed, H.; Moldwin, M.; Kasper, J. C.; Sheehan, J. P.; Forbes, J.; Heine, T.; Case, A. W.; Stevens, M. L.; Sibeck, D. G.

    2015-12-01

    The MarsCAT (Mars Array of ionospheric Research Satellites using the CubeSat Ambipolar Thruster) Mission is a two 6U CubeSat mission to study the ionosphere of Mars proposed for the NASA SIMPLeX opportunity. The mission will investigate the plasma and magnetic structure of the Martian ionosphere, including transient plasma structures, magnetic field structure and dynamics, and energetic particle activity. The transit plan calls for a piggy back ride with Mars 2020 using a CAT burn for MOI, the first demonstration of CubeSat propulsion for interplanetary travel. MarsCAT will make correlated multipoint studies of the ionosphere and magnetic field of Mars. Specifically, the two spacecraft will make in situ observations of the plasma density, temperature, and convection in the ionosphere of Mars. They will also make total electron content measurements along the line of sight between the two spacecraft and simultaneous 3-axis local magnetic field measurements in two locations. Additionally, MarsCAT will demonstrate the performance of new CubeSat telemetry antennas designed at the University of Houston that are designed to be low profile, rugged, and with a higher gain than conventional monopole (whip) antennas. The two MarsCAT CubeSats will have five science instruments: a 3-axis DC magnetometer, adouble-Langmuir probe, a Faraday cup, a solid state energetic particle detector (Science Enhancement Option), and interspacecraft total electron content radio occulation experiment. The MarsCAT spacecraft will be solar powered and equipped with a CAT thruster that can provide up to 4.8 km/s of delta-V, which is sufficient to achieve Mars orbit using the Mars 2020 piggyback. They have an active attitude control system, using a sun sensor and flight-proven star tracker for determination, and momentum wheels for 3-axis attitude control.

  7. MarsCAT: Mars Array of ionospheric Research Satellites using the CubeSat Ambipolar Thruster

    NASA Astrophysics Data System (ADS)

    Bering, Edgar Andrew; Pinsky, Lawrence S.; Li, Liming; Jackson, David; Chen, Ji; Reed, Helen; Moldwin, Mark; Kasper, Justin; Sheehan, J. P.; Forbes, James Richard; Heine, Thomas; Case, Anthony; Stevens, Michael; Sibeck, David G.

    2015-11-01

    The MarsCAT (Mars Array of ionospheric Research Satellites using the CubeSat Ambipolar Thruster) Mission is a two 6U CubeSat mission to study the ionosphere of Mars proposed for the NASA SIMPLeX opportunity. The mission will investigate the plasma and magnetic structure of the Martian ionosphere, including transient plasma structures, magnetic field structure and dynamics, and energetic particle activity. The transit plan calls for a piggy back ride with Mars 2020 using a CAT burn for MOI, the first demonstration of CubeSat propulsion for interplanetary travel. MarsCAT will make correlated multipoint studies of the ionosphere and magnetic field of Mars. Specifically, the two spacecraft will make in situ observations of the plasma density, temperature, and convection in the ionosphere of Mars. They will also make total electron content measurements along the line of sight between the two spacecraft and simultaneous 3-axis local magnetic field measurements in two locations. Additionally, MarsCAT will demonstrate the performance of new CubeSat telemetry antennas designed at the University of Houston that are designed to be low profile, rugged, and with a higher gain than conventional monopole (whip) antennas. The two MarsCAT CubeSats will have five science instruments: a 3-axis DC magnetometer, adouble-Langmuir probe, a Faraday cup, a solid state energetic particle detector (Science Enhancement Option), and interspacecraft total electron content radio occulation experiment. The MarsCAT spacecraft will be solar powered and equipped with a CAT thruster that can provide up to 4.8 km/s of delta-V, which is sufficient to achieve Mars orbit using the Mars 2020 piggyback. They have an active attitude control system, using a sun sensor and flight-proven star tracker for determination, and momentum wheels for 3-axis attitude control.

  8. Ion Escape from the Ionosphere of Titan

    NASA Technical Reports Server (NTRS)

    Hartle, R.; Sittler, E.; Lipatov, A.

    2008-01-01

    Ions have been observed to flow away from Titan along its induced magnetic tail by the Plasma Science Instrument (PLS) on Voyager 1 and the Cassini Plasma Spectrometer (CAPS) on Cassini. In both cases, the ions have been inferred to be of ionospheric origin. Recent plasma measurements made at another unmagnetized body, Venus, have also observed similar flow in its magnetic tail. Much earlier, the possibility of such flow was inferred when ionospheric measurements made from the Pioneer Venus Orbiter (PVO) were used to derive upward flow and acceleration of H(+), D(+) and O(+) within the nightside ionosphere of Venus. The measurements revealed that the polarization electric field in the ionosphere produced the principal upward force on these light ions. The resulting vertical flow of H(+) and D(+) was found to be the dominant escape mechanism of hydrogen and deuterium, corresponding to loss rates consistent with large oceans in early Venus. Other electrodynamic forces were unimportant because the plasma beta in the nightside ionosphere of Venus is much greater than one. Although the plasma beta is also greater than one on Titan, ion acceleration is expected to be more complex, especially because the subsolar point and the subflow points can be 180 degrees apart. Following what we learned at Venus, upward acceleration of light ions by the polarization electric field opposing gravity in the ionosphere of Titan will be described. Additional electrodynamic forces resulting from the interaction of Saturn's magnetosphere with Titan's ionosphere will be examined using a recent hybrid model.

  9. Role of stochasticity in turbulence and convective intermittent transport at the scrape off layer of Ohmic plasma in QUEST

    SciTech Connect

    Banerjee, Santanu Ishiguro, M.; Tashima, S.; Mishra, K.; Zushi, H.; Hanada, K.; Nakamura, K.; Idei, H.; Hasegawa, M.; Fujisawa, A.; Nagashima, Y.; Matsuoka, K.; Nishino, N.; Liu, H. Q.

    2014-07-15

    Statistical features of fluctuations are investigated using the fast camera imaging technique in the scrape of layer (SOL) of electron cyclotron resonance heated Ohmic plasma. Fluctuations in the SOL towards low field side are dominated by coherent convective structures (blobs). Two dimensional structures of the higher order moments (skewness s and kurtosis k) representing the shape of probability density function (PDF) are studied. s and k are seen to be functions of the magnetic field lines. s and k are consistently higher towards the bottom half of the vessel in the SOL showing the blob trajectory along the field lines from the top towards bottom of the vessel. Parabolic relation (k=As{sup 2}+C) is observed between s and k near the plasma boundary, featuring steep density gradient region and at the far SOL. The coefficient A, obtained experimentally, indicates a shift of prominence from pure drift-wave instabilities towards fully developed turbulence. Numerical coefficients characterizing the Pearson system are derived which demonstrates the progressive deviation of the PDF from Gaussian towards gamma from the density gradient region, towards the far SOL. Based on a simple stochastic differential equation, a direct correspondence between the multiplicative noise amplitude, increased intermittency, and hence change in PDF is discussed.

  10. Low- and mid-latitude ionospheric electric fields during the January 1984 GISMOS campaign

    NASA Technical Reports Server (NTRS)

    Fejer, B. G.; Kelley, M. C.; Senior, C.; De La Beaujardiere, O.; Lepping, R.

    1990-01-01

    The electrical coupling between the high-, middle-, and low-latitude ionospheres during January 17-19, 1984 is examined, using interplanetary and high-latitude magnetic field data together with F region plasma drift measurements from the EISCAT, Sondre Stromfjord, Millstone Hill, Saint-Santin, Arecibo, and Jicamarca incoherent scatter radars. The penetration both the zonal and meridional electric field components of high-latitude origin into the low-latitude and the equatorial ionospheres are studied. The observations in the postmidnight sector are used to compare the longitudinal variations of the zonal perturbation electric field with predictions made from global convection models. The results show that the meridional electric field perturbations are considerably more attenuated with decreasing latitude than the zonal fluctuations. It is concluded that variations in the meridional electric field at low latitudes are largely due to dynamo effects.

  11. A two-dimensional kinematic dynamo model of the ionospheric magnetic field at Venus

    SciTech Connect

    Cravens, T.E.; Wu, D. ); Shinagawa, H. )

    1990-11-01

    The ionosphere of Venus was observed by the magnetometer on the Pioneer Venus Orbiter (PVO) to be permeated by a large-scale magnetic field for conditions of high solar wind dynamic pressure. The ionospheric conductivity is very high above 170 km and magnetic flux is carried by the plasma flow both vertically downward and in an antisunward direction. Ohmic dissipation of the electric current allows the magnetic field to diffuse for altitudes below 150-170 km. A number of one-dimensional kinematic dynamo and MHD models have been developed to explain the observed vertical magnetic field profiles, but did not include the effects of horizontal transport. The authors have constructed a two-dimensional kinematic dynamo model of the dayside ionospheric magnetic field at Venus in which the 2-D magnetic induction equation (i.e., magnetic diffusion-convection equation) is numerically solved using specified plasma velocities. The vertical velocity profile is taken from the one-dimensional MHD model of Shinagawa and Cravens (1988) and the horizontal velocities are adapted from published PVO retarding potential analyzer results (Knudsen et al., 1982). They demonstrate that the basic features of the vertical magnetic field profile, such as the presence of a magnetic layer at 170 km, remain unaltered by horizontal flow effects. However, they also show that horizontal plasma flow can strongly affect the magnetic field for altitudes above 300 km.

  12. TOMOGRAPHY OF PLASMA FLOWS IN THE UPPER SOLAR CONVECTION ZONE USING TIME-DISTANCE INVERSION COMBINING RIDGE AND PHASE-SPEED FILTERING

    SciTech Connect

    Svanda, Michal

    2013-09-20

    The consistency of time-distance inversions for horizontal components of the plasma flow on supergranular scales in the upper solar convection zone is checked by comparing the results derived using two k-{omega} filtering procedures-ridge filtering and phase-speed filtering-commonly used in time-distance helioseismology. I show that both approaches result in similar flow estimates when finite-frequency sensitivity kernels are used. I further demonstrate that the performance of the inversion improves (in terms of a simultaneously better averaging kernel and a lower noise level) when the two approaches are combined together in one inversion. Using the combined inversion, I invert for horizontal flows in the upper 10 Mm of the solar convection zone. The flows connected with supergranulation seem to be coherent only for the top {approx}5 Mm; deeper down there is a hint of change of the convection scales toward structures larger than supergranules.

  13. Parametric instabilities as a reason of VLF/ELF plasma turbulence excited in the upper ionosphere by ground based VLF transmitters

    NASA Astrophysics Data System (ADS)

    Kotik, Dmitry

    Recently Parrot et al. (2007) reported the results of the DEMETER satellite observations of strong plasma density and temperature perturbations simultaneously with different events in VLF/ELF electrostatic emissions when the satellite orbit crossed the region about 500 km in the diameter above the ground-based VLF transmitters at the height about 800 km. We have shown that during the night estimated electric field (of the transmitter radiated whistler mode (˜ 0.02-0.05 V/m) in the height region ˜ 500-1000 km exceeds the thresholds of the parametric instabilities responsible for excitation pf the lower hybrid waves, particularly three wave decay of the whistler to ion sound and/or lower hybrid/whistler waves, or induced scattering of whistlers to lower hybrid/whistler waves on thermal ions. To our opinion latter processes are responsible for the phenomena observed by the DEMETER satellite. The work is supported by the RFBR grant 06-02-17334. 1. M. Parrot, J.A. Sauvaud, J.J. Berthelier, J.P. Lebreton Strong ionospheric perturbations generated by powerful VLF ground-based transmitters, X International Seminar on "Low frequency processes in the space plasma", Moscow, November, 2007.

  14. Results of the first statistical study of pioneer Venus orbiter plasma observations in the distant Venus tail: Evidence for a hemispheric asymmetry in the pickup of ionospheric ions

    SciTech Connect

    Intriligator, D.S. )

    1989-02-01

    Pioneer Venus Orbiter plasma and magnetometer observations from the first nine tail seasons of crossings of the Venus wake are used to study ion pickup in the far wake of an unmagnetized object embedded in the solar wind. This first statistical study treats all of the plasma spectra containing pickup ions in the vicinity of the Venus tail. The author finds a hemispheric asymmetry in the pickup of ionospheric ions, with approximately four times more O{sup +} events observed in the northern magnetic hemisphere (where Z{double prime} > O), i.e., the induced electric field points outward, (away from the ionopause boundary) than in the southern (Z{double prime} < O) magnetic hemisphere. Out of a total of 167 large O{sup +} events, 125, or 75%, occurred in the northern hemisphere when position is calculated in terms of Venus radii and 129 or 77% occurred in the northern hemisphere when position is expressed in gyroradii. This hemisphere asymmetry in ion pickup is consistent with the prediction of the Cloutier et al. (1974) mass loading model for Venusian ions above the ionopause boundary.

  15. Next Generation Whole Atmosphere Model (NGWAM) for ionospheric simulation and forecast: status, plans, requirements, and capabilities

    NASA Astrophysics Data System (ADS)

    Akmaev, R. A.; Yudin, V. A.; Viereck, R. A.

    2015-12-01

    The Whole Atmosphere Model (WAM) has been developed in collaboration of the NOAA Space Weather Prediction and Environmental Modeling Centers (SWPC and EMC) by vertical extension of the operational Global Forecast System (GFS) model over the last decade. The model has demonstrated remarkable performance in simulating climatology and daily variability of the upper atmosphere and ionosphere driven from below. Coupled to ionosphere-electrodynamics models it not only reproduced dramatic variations of ionospheric plasma drifts and density distribution observed during sudden stratospheric warmings but also demonstrated predictive capability with lead times up to 2 weeks. WAM has reached a level of maturity to be implemented into operations at the National Weather Service (NWS) in the next few years. Within the same timeframe NWS also plans to substantially upgrade GFS to the Next Generation Global Prediction System (NGGPS). Specific capabilities of NGGPS include in particular a nonhydrostatic dynamical core and the ability to directly simulate important processes such as tropospheric convection at very high resolution globally and without the need for parameterization. This opens an opportunity for development of NGWAM. Specific requirements for extension of NGGPS into NGWAM will be discussed and capabilities of the new models in application to the upper atmosphere and ionosphere dynamics, simulation, and prediction presented.

  16. Convective Raman amplification of light pulses causing kinetic inflation in inertial fusion plasmas

    SciTech Connect

    Ellis, I. N.; Strozzi, D. J.; Williams, E. A.; Winjum, B. J.; Tsung, F. S.; Mori, W. B.; Fahlen, J. E.; Grismayer, T.

    2012-11-15

    We perform 1D particle-in-cell (PIC) simulations using OSIRIS, which model a short-duration ({approx}500{omega}{sub 0}{sup -1} FWHM) scattered light seed pulse in the presence of a constant counter-propagating pump laser with an intensity far below the absolute instability threshold. The seed undergoes linear convective Raman amplification and dominates over fluctuations due to particle discreteness. Our simulation results are in good agreement with results from a coupled-mode solver when we take into account special relativity and the use of finite size PIC simulation particles. We present linear gain spectra including both effects. Extending the PIC simulations past when the seed exits the simulation domain reveals bursts of large-amplitude scattering in many cases, which does not occur in simulations without the seed pulse. These bursts can have amplitudes several times greater than the amplified seed pulse, and we demonstrate that this large-amplitude scattering is the result of kinetic inflation by examining trapped particle orbits. This large-amplitude scattering is caused by the seed modifying the distribution function earlier in the simulation. We perform some simulations with longer duration seeds, which lead to parts of the seeds undergoing kinetic inflation and reaching amplitudes several times more than the steady-state linear theory results. Simulations with continuous seeds demonstrate that the onset of inflation depends on seed wavelength and incident intensity, and we observe oscillations in the reflectivity at a frequency equal to the difference between the seed frequency and the frequency at which the inflationary stimulated Raman scattering grows.

  17. Convective Raman amplification of light pulses causing kinetic inflation in inertial fusion plasmas

    NASA Astrophysics Data System (ADS)

    Ellis, I. N.; Strozzi, D. J.; Winjum, B. J.; Tsung, F. S.; Grismayer, T.; Mori, W. B.; Fahlen, J. E.; Williams, E. A.

    2012-11-01

    We perform 1D particle-in-cell (PIC) simulations using OSIRIS, which model a short-duration (˜500ω0-1 FWHM) scattered light seed pulse in the presence of a constant counter-propagating pump laser with an intensity far below the absolute instability threshold. The seed undergoes linear convective Raman amplification and dominates over fluctuations due to particle discreteness. Our simulation results are in good agreement with results from a coupled-mode solver when we take into account special relativity and the use of finite size PIC simulation particles. We present linear gain spectra including both effects. Extending the PIC simulations past when the seed exits the simulation domain reveals bursts of large-amplitude scattering in many cases, which does not occur in simulations without the seed pulse. These bursts can have amplitudes several times greater than the amplified seed pulse, and we demonstrate that this large-amplitude scattering is the result of kinetic inflation by examining trapped particle orbits. This large-amplitude scattering is caused by the seed modifying the distribution function earlier in the simulation. We perform some simulations with longer duration seeds, which lead to parts of the seeds undergoing kinetic inflation and reaching amplitudes several times more than the steady-state linear theory results. Simulations with continuous seeds demonstrate that the onset of inflation depends on seed wavelength and incident intensity, and we observe oscillations in the reflectivity at a frequency equal to the difference between the seed frequency and the frequency at which the inflationary stimulated Raman scattering grows.

  18. Study of plasma convection and wall interactions in magnetic confinement systems

    NASA Astrophysics Data System (ADS)

    York, T. M.

    1986-06-01

    The subject contract research effort was initiated in September 1976 with two specific tasks: (1) to study the fundamental physics of confinement of an alternate concept (i.e., theta pinch based) devices; and (2) to study and to develop new diagnostic systems for use on major experiments at other locations in the country. There has been active collaboration with Los Alamos National Laboratory and Lawrence Livermore National Laboratory; there has been proposed collaboration with Princeton Plasma Physics Laboratory, Fusion Research Center at the University of Texas, and General Atomics.

  19. Ionospheric disturbance dynamo

    SciTech Connect

    Blanc, M.; Richmond, A.D.

    1980-04-01

    A numerical simulation study of the thermospheric winds produced by auroral heating during magnetic storms, and of their global dynamo effects, establishes the main features of the ionospheric disturbanc dynamo. Driven by auroral heating, a Hadley cell is created with equatorward winds blowing above about 120 km at mid-latitudes. The transport of angular momentum by these winds produces a subrotation of the midlatitude thermosphere, or westward motion with respect to the earth. The westward winds in turn drive equatorward Pedersen currents which accumulate charge toward the equator, resulting in the generation of a poleward electric field, a westward E x B drift, and an eastward current. When realistic local time conductivity variations are simulated, the eastward mid-latitude current is found to close partly via lower latitudes, resulting in an 'anti-Sq' type of current vortex. Both electric field and current at low latitudes thus vary in opposition to their normal quiet-day behavior. This total pattern of distrubance winds, electric fields, and currents is superimposed upon the background quiet-day pattern. When the neutral winds are artificially confined on the nightside, the basic pattern of predominantly westward E x B plasma drifts still prevails on the nightside but no longer extends into the dayside. Considerable observational evidence exists, suggesting that the ionospheric disturbance dynamo has an appreciable influence on storm-time ionospheric electric fields at middle and low latitudes.

  20. Midlatitude ionospheric dynamics and disturbances: Introduction

    NASA Astrophysics Data System (ADS)

    Kintner, Paul M., Jr.; Coster, Anthea J.; Fuller-Rowell, Tim; Mannucci, Anthony J.; Mendillo, Michael; Heelis, Roderick

    Recent discoveries have demonstrated that the ionosphere responds over regions extending from the equator to the poles during geomagnetic storms and experiences the most extreme changes at midlatitudes. The midlatitude ionosphere was first studied during the "discovery era" of radio physics and space flight 50 or more years ago, but for the past three decades the polar and tropical ionosphere have dominated scientific activity, resulting in the false impression that the midlatitude ionosphere was an uninteresting region of known morphology and well-understood processes. During the past five years, however, the ability to image the ionosphere and thermosphere with large arrays of ground-based GPS receivers and satellite-borne UV imagers changed this viewpoint dramatically and led to the inception of the Chapman Conference on Mid-Latitude Ionospheric Dynamics and Disturbances (MIDD) and to this monograph. The most dramatic changes in ionospheric content occur at midlatitudes, not at high or equatorial latitudes. The most extreme examples of ionospheric total electron content (TEC) perturbations occur at midlatitudes during geomagnetic storms, where TEC can change by factors of three to ten over the duration of a magnetic storm. The ionosphere responds to magnetic storms over regions extending from the equator to the poles, where huge volumes of plasma are produced and transported polewards. Sharp gradients in ionospheric content, extending thousands of kilometers, are created by unknown factors. These gradients spawn irregularities that together impact users of RF signals, either transiting across or reflecting from the ionosphere. At higher altitudes, dramatic changes in the ionosphere are accompanied by movement and transport of the plasmasphere.

  1. Inductive-Dynamic Simulation on Locations of Energy Input to and Deposition in the Ionosphere-Thermospher

    NASA Astrophysics Data System (ADS)

    Tu, J.

    2015-12-01

    Recent observations of the net Poynting flux deposition to the ionosphere showed that the strongest energy input from the magnetosphere is in the polar cap where the plasma flow speed is high and not where the flow reverses, implying that the field-aligned current is not the primary agent of the energy transfer and that other physical progresses are at play. In this study we assess locations of the energy transfer and deposition by a simulation conducted with a self-consistent inductive-dynamic (including self-consistent solutions of Faraday's law and retaining inertia terms in the plasma momentum equations) ionosphere-thermosphere model. In a 2-D global geometry (dawn-dusk meridian plane), we solve the multifluid-collisional-Hall MHD equations including photochemistry. The preliminary simulation results demonstrate propagation and evolution of the field-aligned currents and the dynamic processes of the formation of the ionospheric Pedersen currents. By comparing locations of the field-aligned currents and ionosphere/thermosphere heating driven by the magnetospheric convection we show that the energy input to the IT system and the energy dissipation occurs in the polar cap instead of regions where the field-aligned currents reside. The implication of these results is that the field-aligned currents are not the primary agent of the energy transfer from the magnetosphere to the IT system.

  2. Ionospheric wave spectrum measurements

    NASA Technical Reports Server (NTRS)

    Harker, K. J.; Ilic, D. B.; Crawford, F. W.

    1979-01-01

    The local spectrum S(k, omega) of either potential or electron-density fluctuations can be used to determine macroscopic-plasma characteristics such as the local density and temperature, transport coefficients, and drift current. This local spectrum can be determined by measuring the cross-power spectrum. The paper examines the practicality of using the cross-power spectrum analyzer on the Space Shuttle to measure ionospheric parameters. Particular attention is given to investigating the integration time required to measure the cross-power spectral density to a desired accuracy.

  3. Chaotic dynamics of corotating magnetospheric convection

    NASA Technical Reports Server (NTRS)

    Summers, Danny; Mu, Jian-Lin

    1994-01-01

    The corotating plasma convection system of the Jovian magnetosphere is analyzed. The macroscopic (mhd) model introduced by Summers and Mu, (1992) that incorporates the effects of microdiffusion is extended by including previously neglected density effects. We reduce the governing partial differential equations to a third-order ordinary differential system by the Galerkin technique of mode truncation. We carry out such a severe truncation partly in the interests of tractability, and leave open the question of the efficacy of adding additional modes. Exhaustive numerical integrations are carried out to calculate the long-term solutions, and we discover that a rich array of plasma motions is possible, dependent on the value of the height-integrated ionospheric Pederson conductivity Sigma. If Sigma is less than a certain critical value Sigma(sub c), then plasma motion can be expected to be chaotic (or periodic), while if Sigma is greater than Sigma(sub c), then steady state convection is expected. In the former case, whether the plasma motion is chaotic or periodic (and, if periodic, the magnitude of the period) can be very sensitive to the value of Sigma. The value of Sigma(sub c), which is a function of a parameter q that occurs in the assumed form of the stationary radial profile (varies as L(exp -q) of the plasma mass per unit magnetic flux, lies well within the accepted range of values of Sigma for Jupiter, i.e. Sigma greater than or equal to 0.1 mho and less than or equal to 10 mho.

  4. Magnetosphere-ionosphere coupling during plasmoid evolution - First results

    NASA Technical Reports Server (NTRS)

    Hesse, Michael; Birn, Joachim

    1991-01-01

    The influence of magnetosphere-ionosphere coupling on the dynamic evolution of the magnetotail is investigated by a three-dimensional resistive MHD code that includes the effects of the closure of field-aligned currents in a simple resistive model ionosphere. Particular emphasis is on the role of this coupling during substorm evolution and the modification of the latter by the convection driven by the ionospheric electric fields. For comparison, results are presented from a simulation which uses an infinitely conducting ionosphere but is otherwise identical. Comparison of the two simulations shows that the major impact of magnetosphere-ionospheric communication is an acceleration of magnetotail evolution. Otherwise, phenomena in the two models are qualitatively similar. It is concluded that ionospheric effects do not significantly affect substorm associated magnetotail dynamics.

  5. The Unreasonable Success of Magnetosphere-Ionosphere Coupling Theory

    NASA Astrophysics Data System (ADS)

    Vasyliūnas, V. M.

    2002-12-01

    The description of plasma dynamics on the basis of self-consistent coupling between magnetosphere and ionosphere, as first systematized in the early 1970's, is arguably one of the most successful theories in magnetospheric physics. It accounts for the pattern of magnetospheric convection at auroral and low latitudes, the distribution of Birkeland currents, and the dependence on changing orientation of the interplanetary magnetic field. It can incorporate assumed effects, e.g. of particle sources or conductance variations, to almost any degree of complexity at moderate cost in additional computing effort (compare the levels of physics included in advanced versions of the Rice Convection Model and of global MHD simulations, respectively). Such success combined with relative simplicity, however, is possible only because the theory has limited itself in significant ways. It treats the system in effect as doubly two-dimensional: height-integrated ionosphere plus field-line-integrated magnetosphere, with the background magnetic field structure treated as known or derived from some empirical model. It assumes that the system is always in slowly evolving quasi-equilibrium and deals only with time scales long compared to wave propagation times. Hence the theory is not easily applied where genuine 3D aspects (e.g. height and field-line dependence), poorly known or variable magnetic fields (e.g. open field lines), or transient responses e.g. to rapid solar-wind changes are important, and it is intrinsically incapable of describing explosive non-equilibrium developments such as substorm onset. Possible extensions of the theory, comparison with numerical-simulation approaches, and implications for general space plasma physics (E-J vs. B-V) will be discussed.

  6. Low-Frequency Waves in HF Heating of the Ionosphere

    NASA Astrophysics Data System (ADS)

    Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

    2016-02-01

    Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

  7. Ionospheric modification by rocket effluents. Final report

    SciTech Connect

    Bernhardt, P.A.; Price, K.M.; da Rosa, A.V.

    1980-06-01

    This report describes experimental and theoretical studies related to ionospheric disturbances produced by rocket exhaust vapors. The purpose of our research was to estimate the ionospheric effects of the rocket launches which will be required to place the Satellite Power System (SPS) in operation. During the past year, we have developed computational tools for numerical simulation of ionospheric changes produced by the injection of rocket exhaust vapors. The theoretical work has dealt with (1) the limitations imposed by condensation phenomena in rocket exhaust; (2) complete modeling of the ionospheric depletion process including neutral gas dynamics, plasma physics, chemistry and thermal processes; and (3) the influence of the modified ionosphere on radio wave propagation. We are also reporting on electron content measurements made during the launch of HEAO-C on Sept. 20, 1979. We conclude by suggesting future experiments and areas for future research.

  8. Theory for substorms triggered by sudden reductions in convection

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1996-01-01

    Many substorm expansions are triggered by interplanetary magnetic field changes that reduce magnetospheric convection. This suggests that expansion onsets are a result of a reduction in the large-scale electric field imparted to the magnetosphere from the solar wind. Such a reduction disrupts the inward motion and energization of plasma sheet particles that occur during the growth phase. It is proposed that the resulting magnetic drift of particles and a large dawn to dusk gradient in the ion energies leads to a longitudinally localized reduction in the plasma pressure, and thus, to the current wedge formation. This theory accounts for the rapid development of the expansion phase relative to growth phase, the magnitude of the wedge currents, the speeds of tailward and westward expansion of the current reduction region in the equatorial plane, and the speeds of the poleward and westward motion of active aurora in the ionosphere.

  9. A Study of Steady Magnetospheric Convection Using High Latitude Magnetometers

    NASA Astrophysics Data System (ADS)

    de Silva, J. T.; Erickson, K. N.; Engebretson, M. J.; Murr, D. L.; Hughes, W. J.

    2001-05-01

    Magnetometer data from the MACCS and CANOPUS arrays in northern North America have been analyzed during two of the intervals of steady magnetospheric convection identified by the GEM community, January 29-30 and February 3-4, 1998. These intervals were characterized by extended periods of southward interplanetary magnetic field (negative IMF Bz), and by the absence of substorms. The patterns of ionospheric current flow on the dayside were found to be in general agreement with the disturbance current system, SD, originally described by Silsbee and Vestine [1942]. This indicates that during extended periods of southward IMF the convection on the dayside is the same whether or not there are substorms. When plasma flow patterns measured by the SuperDARN auroral radar network were available for comparison, these patterns agreed with the patterns inferred from magnetometers. Further study will investigate convection patterns on the nightside, and a similar study of convection for the southern high latitude region will be conducted using data from Antarctic stations.

  10. Earthquake-Ionosphere Coupling Processes

    NASA Astrophysics Data System (ADS)

    Kamogawa, Masashi

    After a giant earthquake (EQ), acoustic and gravity waves are excited by the displacement of land and sea surface, propagate through atmosphere, and then reach thermosphere, which causes ionospheric disturbances. This phenomenon was detected first by ionosonde and by HF Doppler sounderin the 1964 M9.2 Great Alaskan EQ. Developing Global Positioning System (GPS), seismogenic ionospheric disturbance detected by total electron content (TEC) measurement has been reported. A value of TEC is estimated by the phase difference between two different carrier frequencies through the propagation in the dispersive ionospheric plasma. The variation of TEC is mostly similar to that of F-region plasma. Acoustic-gravity waves triggered by an earthquake [Heki and Ping, EPSL, 2005; Liu et al., JGR, 2010] and a tsunami [Artu et al., GJI, 2005; Liu et al., JGR, 2006; Rolland, GRL, 2010] disturb the ionosphere and travel in the ionosphere. Besides the traveling ionospheric disturbances, ionospheric disturbances excited by Rayleigh waves [Ducic et al, GRL, 2003; Liu et al., GRL, 2006] as well as post-seismic 4-minute monoperiodic atmospheric resonances [Choosakul et al., JGR, 2009] have been observed after the large earthquakes. Since GPS Earth Observation Network System (GEONET) with more than 1200 GPS receiving points in Japan is a dense GPS network, seismogenic ionospheric disturbance is spatially observed. In particular, the seismogenic ionospheric disturbance caused by the M9.0 off the Pacific coast of Tohoku EQ (henceforth the Tohoku EQ) on 11 March 2011 was clearly observed. Approximately 9 minutes after the mainshock, acoustic waves which propagated radially emitted from the tsunami source area were observed through the TEC measurement (e. g., Liu et al. [JGR, 2011]). Moreover, there was a depression of TEC lasting for several tens of minutes after a huge earthquake, which was a large-scale phenomenon extending to a radius of a few hundred kilometers. This TEC depression may be

  11. The low- and equatorial-latitude ionosphere at a height of 500 km in the course of magnetospheric-ionospheric disturbances during September-December 1977 /according to data from the Cosmos-900 satellite/

    NASA Astrophysics Data System (ADS)

    Gdalevich, G. L.; Vsekhsviatskaia, I. S.; Ozerov, V. D.; Soboleva, T. N.

    1982-11-01

    Cosmos-900 data on variations of charged-particles concentration, acquired at various magnetic-storm phases during September-December 1977, were used to analyze the effect of magnetospheric-ionospheric disturbances on the ionosphere at low and equatorial latitudes. It is shown that the equatorial anomaly in the latitudinal distribution of charged particles often disappears during the daytime, and that this anomaly during the nighttime cannot be explained by generally accepted ideas concerning plasma convection at low latitudes. The appearance of concentration irregularities is found to depend on the rate of change of Dst variations, especially at the magnetic-storm recovery phase. The appearance of irregularities in the region of the largest charged-particle concentration gradients lends support to the gradient-drift mechanism for the formation of these irregularities.

  12. Models of Titan's Ionosphere

    NASA Astrophysics Data System (ADS)

    Robertson, I. P.; Cravens, T. E.; Waite, J. H.; Wahlund, J.; Yelle, R. V.; Vuitton, V.; Coates, A.; Magee, B.; Gell, D. A.

    2007-12-01

    During the TA and T18 encounters with Titan, in situ measurements were made of Titan's atmosphere and ionosphere by several instruments on board the Cassini Orbiter, including the Ion and Neutral Mass Spectrometer (INMS), the Langmuir probe on the Cassini Radio and Plasma Wave Experiment (RPWS), and the Cassini Plasma Spectrometer Subsystem (CAPS). Both of these encounters were on the day as well as the night side of Titan. The model uses neutral densities measured by the INMS instrument and the electron temperature was measured by the RPWS instrument. The model also includes energetic electron fluxes measured by the CAPS instrument, which act as an important source of ionization on the night side. The modeled ion densities are compared with densities measured by INMS in its Open Source mode.

  13. Ionospheric plasma flow about a system of electrically biased flat plates. M.S. Thesis - Cleveland State Univ. Final Report

    NASA Technical Reports Server (NTRS)

    Herr, Joel L.

    1993-01-01

    The steady state interaction of two electrically biased parallel plates immersed in a flowing plasma characteristic of low earth orbit is studied numerically. Fluid equations are developed to describe the motion of the cold positively charged plasma ions, and are solved using finite-differences in two dimensions on a Cartesian grid. The behavior of the plasma electrons is assumed to be described by the Maxwell-Boltzmann distribution. Results are compared to an analytical and a particle simulation technique for a simplified flow geometry consisting of a single semi-infinite negatively biased plate. Comparison of the extent of the electrical disturbance into the flowing plasma and the magnitude of the current collected by the plate is very good. The interaction of two equally biased parallel plates is studied as a function of applied potential. The separation distance at which the current collected by either plate decreases by five and twenty percent is determined as a function of applied potential. The percent decreases were based on a non-interacting case. The decrease in overall current is caused by a decrease in ionic density in the region between the plates. As the separation between the plates decreases, the plates collect the ions at a faster rate than they are supplied to the middle region by the oncoming plasma flow. The docking of spacecraft in orbit is simulated by moving two plates of unequal potential toward one another in a quasi-static manner. One plate is held at a large negative potential while the other floats electrically in the resulting potential field. It is found that the floating plate does not charge continuously negative as it approaches the other more negatively biased plate. Instead, it charges more and then less negative as ionic current decreases and then increases respectively upon approach. When the two plates come into contact, it is expected that the electrically floating plate will charge rapidly negative to a potential near that of

  14. Relative importance of horizontal and vertical transports to the formation of ionospheric storm-enhanced density and polar tongue of ionization

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Wang, Wenbin; Burns, Alan; Solomon, Stanley C.; Zhang, Shunrong; Zhang, Yongliang; Huang, Chaosong

    2016-08-01

    There are still uncertainties regarding the formation mechanisms for storm-enhanced density (SED) in the high and subauroral latitude ionosphere. In this work, we deploy the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM) and GPS total electron content (TEC) observations to identify the principle mechanisms for SED and the tongue of ionization (TOI) through term-by-term analysis of the ion continuity equation and also identify the advantages and deficiencies of the TIEGCM in capturing high-latitude and subauroral latitude ionospheric fine structures for the two geomagnetic storm events occurring on 17 March 2013 and 2015. Our results show that in the topside ionosphere, upward E × B ion drifts are most important in SED formation and are offset by antisunward neutral winds and downward ambipolar diffusion effects. In the bottomside F region ionosphere, neutral winds play a major role in generating SEDs. SED signature in TEC is mainly caused by upward E × B ion drifts that lift the ionosphere to higher altitudes where chemical recombination is slower. Horizontal E × B ion drifts play an essential role in transporting plasma from the dayside convection throat region to the polar cap to form TOIs. Inconsistencies between model results and GPS TEC data were found: (1) GPS relative TEC difference between storm time and quiet time has "holes" in the dayside ion convection entrance region, which do not appear in the model results. (2) The model tends to overestimate electron density enhancements in the polar region. Possible causes for these inconsistencies are discussed in this article.

  15. Ionospheric irregularity physics modelling. Memorandum report

    SciTech Connect

    Ossakow, S.L.; Keskinen, M.J.; Zalesak, S.T.

    1982-02-09

    Theoretical and numerical simulation techniques have been employed to study ionospheric F region plasma cloud striation phenomena, equatorial spread F phenomena, and high latitude diffuse auroral F region irregularity phenomena. Each of these phenomena can cause scintillation effects. The results and ideas from these studies are state-of-the-art, agree well with experimental observations, and have induced experimentalists to look for theoretically predicted results. One conclusion that can be drawn from these studies is that ionospheric irregularity phenomena can be modelled from a first principles physics point of view. Theoretical and numerical simulation results from the aforementioned ionospheric irregularity areas will be presented.

  16. The response of the high-latitude ionosphere to the coronal mass ejection event of April 6, 2000: A practical demonstration of space weather nowcasting with the Super Dual Auroral Radar Network HF radars

    NASA Astrophysics Data System (ADS)

    Ruohoniemi, J. M.; Barnes, R. J.; Greenwald, R. A.; Shepherd, S. G.

    2001-12-01

    The ionosphere at high latitudes is the site of important effects in space weather. These include strong electrical currents that may disrupt power systems through induced currents and density irregularities that can degrade HF and satellite communication links. With the impetus provided by the National Space Weather Program, the radars of the Super Dual Auroral Radar Network have been applied to the real-time specification (``nowcasting'') of conditions in the high-latitude ionosphere. A map of the plasma convection in the northern high-latitude ionosphere is continually generated at the Johns Hopkins University Applied Physics Laboratory (JHU/APL) SuperDARN web site using data downloaded in real time from the radars via Internet connections. Other nowcast items include information on the conditions of HF propagation, the spatial extent of auroral effects, and the total cross polar cap potential variation. Time series of various parameters and an animated replay of the last 2 hours of convection patterns are also available for review. By comparing with simultaneous measurements from an upstream satellite, it is possible to infer the effective delay from the detection of changes in the solar wind at the satellite to the arrival of related effects in the high-latitude ionosphere. We discuss the space weather products available from the JHU/APL SuperDARN web site and their uses by simulating a nowcast of the ionosphere on April 6, 2000, during the arrival of a coronal mass ejection (CME) -related shock. The nowcast convection pattern in particular satisfies a critical need for timely, comprehensive information on ionospheric electric fields.

  17. ALTAIR Radar Plasma Drifts and in situ Electric and Magnetic Field Measurements on Two Sounding Rockets and the C/NOFS Satellite in the Low Latitude Ionosphere at Sunset

    NASA Astrophysics Data System (ADS)

    Kudeki, Erhan; Pfaff, Robert; Rowland, Douglas; Klenzing, Jeffrey; Freudenreich, Henry

    2016-07-01

    We present ALTAIR incoherent scatter radar plasma drifts and in situ electric field, magnetic field, and plasma density measurements made simultaneously with probes on two sounding rockets and the C/NOFS satellite in the low latitude ionosphere in the vicinity of Kwajalein Atoll. The coincident data were gathered during sunset conditions prior to a spread-F event during the NASA EVEX Campaign. The sounding rocket apogees were 180 km and 330 km, while the C/NOFS altitude in this region was ~ 390 km. Electric field data from all three platforms display upwards vertical plasma drifts, while the zonal drifts change direction as a function of altitude and/or local time. The variable drifts provide evidence of a dynamic plasma environment which may contribute to the unstable conditions necessary for spread-F instabilities to form.

  18. Ionospheric hot spot at high latitudes

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Sojka, J. J.

    1982-01-01

    Schunk and Raitt (1980) and Sojka et al. (1981) have developed a model of the convecting high-latitude ionosphere in order to determine the extent to which various chemical and transport processes affect the ion composition and electron density at F-region altitudes. The numerical model produces time-dependent, three-dimensional ion density distributions for the ions NO(+), O2(+), N2(+), O(+), N(+), and He(+). Recently, the high-latitude ionospheric model has been improved by including thermal conduction and diffusion-thermal heat flow terms. Schunk and Sojka (1982) have studied the ion temperature variations in the daytime high-latitude F-region. In the present study, a time-dependent three-dimensional ion temperature distribution is obtained for the high-latitude ionosphere for an asymmetric convection electric field pattern with enhanced flow in the dusk sector of the polar region. It is shown that such a convection pattern produces a hot spot in the ion temperature distribution which coincides with the location of the strong convection cell.

  19. The ionospheric signature of flux transfer events

    NASA Technical Reports Server (NTRS)

    Cowley, S. W. H.; Freeman, M. P.; Lockwood, Mike; Smith, M. F.

    1991-01-01

    The effects at ionospheric heights which take place when transient reconnection events (i.e., Flux Tranfer Events (FTEs)) occur at the dayside magnetopause are considered. The nature of the FTE related ionospheric flows, the associated current systems, and the plasma precipitation, are discussed. In particular, the nature of the time dependent cusp precipitation which occurs on this case is outlined and expectations are compared with those based on steady magnetopause reconnection.

  20. The Role of Polar Cap Flux Tube Deformation and Magnetosheath Plasma Beta in the Saturation of the Region 1 Field-Aligned Current System

    NASA Astrophysics Data System (ADS)

    Wilder, F. D.; Eriksson, S.; Wiltberger, M. J.

    2014-12-01

    The phenomena of cross-polar cap potential (CPCP) and ionospheric field-aligned current (FAC) saturation remains largely unexplained. In this study, we expand upon the Alfvén Wing model of CPCP saturation by investigating its impact on the magnetosphere-ionosphere current system, particularly the Region 1 FAC input into the polar cap. Our hypothesis is that the ability of open flux tubes to deform in response to applied fluid stress from the magnetosheath is governed by the magnetosheath plasma beta, which in turn governs the Maxwell stress imposed on ionospheric plasma from the magnetosphere. This leads both the Region 1 FAC input as well as the ionospheric convection strength, as represented by the CPCP, to saturate in response to the interplanetary magnetic field (IMF) driving. We perform 32 simulations using the Lyon-Fedder-Mobarry (LFM) Magnetohydrodynamic (MHD) model with varying solar wind density and IMF strength, and demonstrate that the plasma beta does govern the deformation of polar cap and lobe field lines, as well as the non-linear response of the Region 1 FAC system to increasingly southward IMF. Further, we show that the current-voltage relationship in the ionosphere also shows a dependence on the plasma beta in the magnetosheath, with the ionosphere becoming more resistive at lower beta.

  1. Formation of polar ionospheric tongue of ionization during minor geomagnetic disturbed conditions

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Nakamura, Takuji; Liu, Libo; Wang, Wenbin; Balan, Nanan; Nishiyama, Takanori; Hairston, Marc R.; Thomas, E. G.

    2015-08-01

    Previous investigations of ionospheric storm-enhanced density (SED) and tongue of ionization (TOI) focused mostly on the behavior of TOI during intense geomagnetic storms. Little attention has been paid to the spatial and temporal variations of TOI during weak to moderate geomagnetic disturbed conditions. In this paper we investigate the source and development of TOI during a moderate geomagnetic storm on 14 October 2012. Multi-instrumental observations including GPS total electron content (TEC), Defense Meteorological Satellite Program (DMSP) in situ measured total ion concentration and ion drift velocity, SuperDARN measured polar ion convection patterns, and electron density profiles from the Poker Flat Incoherent Scatter Radar (PFISR) have been utilized in the current analysis. GPS TEC maps show salient TOI structures persisting for about 5 h over high latitudes of North America on 14 October 2012 in the later recovery phase of the storm when the magnitudes of IMF By and Bz were less than 5 nT. The PFISR electron density profiles indicate that the extra ionization for TEC enhancements mainly occurred in the topside ionosphere with no obvious changes in the bottomside ionosphere and vertical plasma drifts. Additionally, there were no signatures of penetration electric fields in the equatorial electrojet data and upward ion drifts at high latitudes. At the same time, strong subauroral polarization streams with ion drift speeds exceeding 2.5 km/s carried sunward fluxes and migrated toward lower latitudes for about 5° based on the DMSP cross-track drift measurements. Based on those measurements, we postulate that the combined effects of initial build-up of ionization at midlatitudes through daytime production of ionization and equatorward (or less poleward than normal daytime) neutral wind reducing downward diffusion along the inclined filed lines, and an expanded polar ion convection pattern and its associated horizontal plasma transport are important in the

  2. Plasma transport driven by the Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Ma, X.; Delamere, P. A.; Otto, A.

    2016-06-01

    Two important differences between the giant magnetospheres (i.e., Jupiter's and Saturn's magnetospheres) and the terrestrial magnetosphere are the internal plasma sources and the fast planetary rotation. Thus, there must be a radially outward flow to transport the plasma to avoid infinite accumulation of plasma. This radial outflow also carries the magnetic flux away from the inner magnetosphere due to the frozen-in condition. As such, there also must be a radial inward flow to refill the magnetic flux in the inner magnetosphere. Due to the similarity between Rayleigh-Taylor (RT) instability and the centrifugal instability, we use a three-dimensional RT instability to demonstrate that an interchange instability can form a convection flow pattern, locally twisting the magnetic flux, consequently forming a pair of high-latitude reconnection sites. This process exchanges a part of the flux tube, thereby transporting the plasma radially outward without requiring significant latitudinal convection of magnetic flux in the ionosphere.

  3. Investigation of low-latitude ionospheric irregularities and their relationship to equatorial plasma bubbles using Sanya VHF radar

    NASA Astrophysics Data System (ADS)

    Ning, B.; Li, G.; Hu, L.

    2011-12-01

    A VHF radar has been set up at Sanya (18.34° N, 109.62° E, geomagnetic latitude 7.04°N), China in 2009. On the basis of the E, valley and F region irregularity observations detected by the Sanya VHF radar during equinoctial months, we focus on the simultaneous observations of E region irregularities disruption and valley region irregularities generation during the presence of post-sunset F region bubble structures. We stress that both the low latitude the E region irregularities (ERI) disruption and valley region irregularities (VRI) generation are associated with the development of post-sunset equatorial plasma bubble (EPB) structures. It is suggested that the electric field coupling from the unstable equatorial F region to low-latitude E and valley region could trigger and inhibit the occurrence of irregularities, depending on the polarity of the polarization electric field associated with the bifurcation of equatorial plasma bubbles. The mapping of upward/eastward and downward/eastward electric field associated with the west-tilted and east-tilted bubble structures, may be responsible for the disruption of E region irregularities, and the generation of valley region irregularities, respectively. However, more observations from multi instruments will be required to confirm such a scenario that the multi bifurcated EPBs play crucial roles for the simultaneous occurrence of low latitude ERI disruption and VRI generation.

  4. Three-Dimensional Particle-in-Cell Simulations of Wave Excitation by Conventional and Parametric Antennas in the Ionospheric Plasma

    NASA Astrophysics Data System (ADS)

    Main, Daniel; Kim, Tony; Caplinger, James; Sotnokiv, Vladimir; Paraschiv, I.; Rose, David

    2015-11-01

    Conventional antennas immersed in a cold, magnetized plasma (CMP) and operating in the very low frequency (VLF) range (e.g. loop and dipole antennas) excite predominately the electrostatic part of the wave spectrum. For example, loop antennas excited in the frequency range ωLH < ω <ωce produce electrostatic lower oblique resonance (LOR) waves. The goal of our research is to increase power radiated into the electromagnetic part of the VLF wave spectrum. Electromagnetic whistler waves are generated due to a nonlinear coupling of LOR and ion acoustic (IA) waves inside a plasma volume around two conventional antennas. Ion acoustic type density perturbations can be excited by a conventional dipole antenna with frequencies in the range ωci < ω <ωLH . In this poster we show three-dimensional electric field patterns from the loop and dipole antennas and the EM spectrum excited due to the parametric interaction. (NOTE: LH = lower hybrid, ce = electron cyclotron,ci=ion cyclotron).

  5. A statistical study of the inner edge of the electron plasma sheet and the net convection potential as a function of geomagnetic activity

    NASA Astrophysics Data System (ADS)

    Jiang, F.; Kivelson, M. G.; Walker, R. J.; Khurana, K. K.; Angelopoulos, V.; Hsu, T.

    2011-06-01

    A widely accepted explanation of the location of the inner edge of the electron plasma sheet and its dependence on electron energy is based on drift motions of individual particles. The boundary is identified as the separatrix between drift trajectories linking the tail to the dayside magnetopause (open paths) and trajectories closed around the Earth. A statistical study of the inner edge of the electron plasma sheet using THEMIS Electrostatic Analyzer plasma data from November 2007 to April 2009 enabled us to examine this model. Using a dipole magnetic field and a Volland-Stern electric field with shielding, we find that a steady state drift boundary model represents the average location of the electron plasma sheet boundary and reflects its variation with the solar wind electric field in the local time region between 21:00 and 06:00, except at high activity levels. However, the model does not reproduce the observed energy dispersion of the boundaries. We have also used the location of the inner edge of the electron plasma sheet to parameterize the potential drop of the tail convection electric field as a function of solar wind electric field (Esw) and geomagnetic activity. The range of Esw examined is small because the data were acquired near solar minimum. For the range of values tested (meaningful statistics only for Esw < 2 mV/m), reasonably good agreement is found between the potential drop of the tail convection electric field inferred from the location of the inner edge and the polar cap potential drop calculated from the model of Boyle et al. (1997).

  6. Assessing the Relative Impact of Distinct Ionospheric Outflow Populations on Geospace Dynamics using Multi-Fluid Global MHD simulations

    NASA Astrophysics Data System (ADS)

    Brambles, O.; Lotko, W.; Ouellette, J.; Zhang, B.; Lyon, J.; Wiltberger, M. J.

    2014-12-01

    Satellite observations and numerical modeling studies have demonstrated that ionospheric ion outflows of different species, source locations and energies populate and interact with distinct regions of the magnetosphere, and therefore can have profoundly different impacts on the coupled solar wind-magnetosphere-ionosphere (SWMI) system. In previous modeling studies, multi-fluid global simulations of the SWMI interaction typically use one fluid to model the solar wind and a second fluid to represent the outflowing ions. These studies are limited as they are incapable of tracking multiple, distinct ionosphere-sourced ion populations. Either significant ion populations and their influence must be excluded from the simulation or multiple ion populations must be combined into a single fluid. In this study, a multi-fluid adaption of the Lyon-Fedder-Mobarry (MFLFM) model that is capable of including numerous separate fluids is used to: (1) evaluate how different outflowing ion populations propagate in the magnetosphere and enter the tail, (2) determine their resulting magnetospheric distribution, and (3) calculate their relative impacts on SWMI coupling. The outflow flux for each population is regulated using causally driven models based on empirical data. These models include specifications for transversely accelerated O+ originating from the cusp and nightside auroral region, H+ polar wind outflow and the plasmasphere. The outflow distributions and hemispheric outflow flux resulting from these models, and their resulting composition in the magnetosphere are validated using satellite data. The effects of each individual ion source on dayside reconnection, electrodynamic magnetosphere-ionosphere coupling and magnetotail processes are evaluated. Among other effects, we find that ionospheric ions that are entrained directly into the warm plasma cloak are more effective at reducing the dayside reconnection potential than ions that are transported further downtail and are

  7. Magnetosphere sawtooth oscillations induced by ionospheric outflow.

    PubMed

    Brambles, O J; Lotko, W; Zhang, B; Wiltberger, M; Lyon, J; Strangeway, R J

    2011-06-01

    The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O(+) outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their pressure distends the nightside magnetic field. When the outflow fluence exceeds a threshold, magnetic field tension cannot confine the accumulating fluid; an O(+)-rich plasmoid is ejected, and the field dipolarizes. Below the threshold, the magnetosphere undergoes quasi-steady convection. Repetition and the sawtooth period are controlled by the strength of the SW-M-I interaction, which regulates the outflow fluence. PMID:21636770

  8. Magnetosphere sawtooth oscillations induced by ionospheric outflow.

    PubMed

    Brambles, O J; Lotko, W; Zhang, B; Wiltberger, M; Lyon, J; Strangeway, R J

    2011-06-01

    The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O(+) outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their pressure distends the nightside magnetic field. When the outflow fluence exceeds a threshold, magnetic field tension cannot confine the accumulating fluid; an O(+)-rich plasmoid is ejected, and the field dipolarizes. Below the threshold, the magnetosphere undergoes quasi-steady convection. Repetition and the sawtooth period are controlled by the strength of the SW-M-I interaction, which regulates the outflow fluence.

  9. Effects of modeled ionospheric conductance and electron loss on self-consistent ring current simulations during the 5-7 April 2010 storm

    NASA Astrophysics Data System (ADS)

    Chen, Margaret W.; Lemon, Colby L.; Guild, Timothy B.; Keesee, Amy M.; Lui, Anthony; Goldstein, Jerry; Rodriguez, Juan V.; Anderson, Phillip C.

    2015-07-01

    We investigate the effects of different ionospheric conductance and electron loss models on ring current dynamics during the large magnetic storm of 5-7 April 2010 using the magnetically and electrically self-consistent Rice Convection Model-Equilibrium (RCM-E). The time-varying RCM-E proton distribution boundary conditions are specified using a combination of TWINS 1 and 2 ion temperature maps and in situ THEMIS and GOES spectral measurements in the plasma sheet. With strong electron pitch-angle diffusion, the simulated equatorial ring current electron pressure is weak with (1) uniform conductance or (2) conductance based on parameters from the International Reference Ionosphere 2007 and the feedback of simulated precipitating electrons. With the Chen and Schulz electron loss model that includes strong diffusion in the plasma sheet and weak diffusion in the plasmasphere, the stormtime equatorial RCM-E electron pressure is enhanced in the inner magnetosphere from midnight through dawn to the dayside. The enhancement extends to lower geocentric distance with uniform conductance than with the more realistic ionospheric conductance model due to electric field shielding effects. Electron losses affect not only the simulated electron pressures, but through magnetospheric-ionospheric coupling, the redistributed electric and magnetic fields affect the ring current proton transport. The simulations reproduced features observed by in situ magnetic field and proton flux data, and TWINS global ENA observations. The simulated stormtime ring current energization can vary significantly depending on the ionospheric conductance and electron loss model used. Thus, it is important to incorporate realistic descriptions of ionospheric conductance and electron losses in inner magnetospheric models.

  10. The Ionospheric Focused Heating experiment

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Siefring, C. L.; Rodriguez, P.; Haas, D. G.; Baumback, M. M.; Romero, H. A.; Solin, D. A.; Djuth, F. T.; Duncan, L. M.; Hunton, D. E.; Pollock, C. J.; Sulzer, M. P.; Tepley, C. A.; Wagner, L. S.; Goldstein, J. A.

    1995-09-01

    The Ionospheric Focused Heating rocket was launched on May 30, 1992. The sounding rocket carried an instrument and chemical payload along a trajectory that crossed the intersection of the beams from the 430-MHz incoherent scatter radar and the 5.1-MHz high-power radio wave facility near Arecibo. The release of 30 kg of CF3Br into the F region at 285 km altitude produced an ionospheric hole that acted like a convergent lens to focus the HF transmissions. The power density inside the radio beam was raised by 12 dB immediately after the release. A wide range of new processes were recorded by in situ and ground-based instruments. Measurements by instruments flying through the modified ionosphere show small-scale microcavities (<1 m) and downshifted electron plasma (Langmuir) waves inside the artificial cavity, electron density spikes at the edge of the cavity, and Langmuir waves coincident with ion gyroradius (4 m) cavities near the radio wave reflection altitude. The Arecibo incoherent scatter radar showed 20 dB or greater enhancements in ion acoustic and Langmuir wave turbulence after the 5.1-MHz radio beam was focused by the artificial lens. Enhancements in airglow from chemical reactions and, possibly, electron acceleration were recorded with optical instruments. The Ionospheric Focused Heating experiment verified some of the preflight predictions and demonstrated the value of active experiments that combine high-power radio waves with chemical releases.

  11. Direct observations of the role of convection electric field in the formation of a polar tongue of ionization from storm enhanced density

    NASA Astrophysics Data System (ADS)

    Thomas, E. G.; Baker, J. B. H.; Ruohoniemi, J. M.; Clausen, L. B. N.; Coster, A. J.; Foster, J. C.; Erickson, P. J.

    2013-03-01

    examine the relationship of convection electric fields to the formation of a polar cap tongue of ionization (TOI) from midlatitude plumes of storm enhanced density (SED). Observations from the geomagnetic storm on 26-27 September 2011 are presented for two distinct SED events. During an hour-long period of geomagnetic activity driven by a coronal mass ejection, a channel of high-density F region plasma was transported from the dayside subauroral ionosphere and into the polar cap by enhanced convection electric fields extending to middle latitudes. This TOI feature was associated with enhanced HF backscatter, indicating that it was the seat of active formation of small-scale irregularities. After the solar wind interplanetary magnetic field conditions quieted and the dayside convection electric fields retreated to higher latitudes, an SED plume was observed extending to, but not entering, the dayside cusp region. This prominent feature in the distribution of total electron content (TEC) persisted for several hours and elongated in magnetic local time with the rotation of the Earth. No ionospheric scatter from SuperDARN radars was observed within this SED region. The source mechanism (enhanced electric fields) previously drawing the plasma from midlatitudes and into the polar cap as a TOI was no longer active, resulting in a fossil feature. We thus demonstrate the controlling role exercised by the convection electric field in generating a TOI from midlatitude SED.

  12. Ionosphere-Plasmasphere coupling using the ionosphere-plasmasphere-electrodynamics (IPE) model

    NASA Astrophysics Data System (ADS)

    Maruyama, N.; Richards, P. G.; Fedrizzi, M.; Fuller-Rowell, T. J.; Fang, T. W.; Codrescu, M.; Pierrard, V.; Denton, M.

    2015-12-01

    A close connection between ionospheric SEDs and plasmaspheric plumes has been reported during the main phase of magnetic storms in previous studies. The temporal and spatial variation of the connection has not yet been studied in detail, as the plasmas in ionosphere and plasmasphere get redistributed dynamically during various phases of a storm. Furthermore, how the Ionosphere-Plasmasphere coupling depends on the types of the solar wind driving conditions has not yet been studied. A newly developed global three dimensional ionosphere-plasmasphere-electrodynamics (IPE) model is used to address the coupling between the ionosphere and plasmasphere. IPE model has reproduced the Storm Enhanced Density plume feature in TEC being transported into cusp and over the pole, characterized as the Tongue of Ionization (TOI). Furthermore, the same simulation reveals the plasmaspheric plume like structure in the magnetospheric equatorial plane. Our simulations suggest that neither SAPS nor midlatitude SED bulge is essential in reproducing the SED plume-like features. A term analysis of the ion continuity equations in the IPE model has indicated that the SED plume/TOI feature observed in the ionosphere is produced due primarily to a combination of plasma transport and production/loss, which is supportive of previous studies. However, the plasmaspheric plume responds differently to that of the ionospheric plume depending on the various setting of the numerical experiments. The results indicate a need of a careful examination of the relative importance of the plasma transport between the parallel and perpendicular directions to the magnetic field in both the ionosphere and plasmasphere. In this presentation, we will compare how the ionosphere-plasmasphere coupling depends on the solar wind driving conditions for the selected campaign events.

  13. Does an ionospheric hole appear after an inland earthquake?

    NASA Astrophysics Data System (ADS)

    Kamogawa, Masashi; Kanaya, Tatsuya; Orihara, Yoshiaki; Toyoda, Atsushi; Suzuki, Yuko; Togo, Shoho; Liu, Jann-Yenq

    2015-11-01

    Ionospheric disturbances occurred as a result of the tsunami associated with the 2011 M9.0 off the Pacific Coast of the Tohoku earthquake (EQ). The ionospheric disturbances propagated radially from the tsunami source area, termed the traveling ionospheric disturbance. In addition to the traveling ionospheric disturbance, an ionospheric plasma depression lasting for approximately 1 h occurred above the tsunami source area, called a tsunami ionospheric hole. In this study, we compare the ionospheric disturbances caused by large inland and submarine EQs to investigate whether an ionospheric plasma depression only occurs in association with a tsunami. Note that we term an EQ with a tsunami a submarine EQ. To investigate the presence of a plasma depression, i.e., an ionospheric hole, associated with an inland EQ, data on total electron content between the global positioning system satellite and its receivers were used. Comparison of two inland and two submarine EQ events with similar magnitudes around 7 showed that ionospheric holes were observed only for the submarine EQs. This discrepancy might be attributed to the different excitation amplitudes of the atmospheric acoustic waves between the unidirectional fault displacement and the tsunami uplift/depression, corresponding to quarter and one-period variations. From this hypothesis, we predicted that an ionospheric hole could be observed after a significantly large inland EQ with a sufficiently large vertical ground displacement. In fact, we recognized the ionospheric hole generated by the large inland EQ that recently occurred in the Nepal with the magnitude of 7.8 on 25 April 2015.

  14. Ionospheric Challenges for GNSS Based Augmentation Systems

    NASA Astrophysics Data System (ADS)

    Doherty, P.; Valladares, C. E.

    2007-12-01

    The ionosphere is a highly dynamic physical phenomenon that presents a variable source of error for Global Navigation Satellite System (GNSS) signals and GNSS based operational systems. The Federal Aviation Administration's (FAA) Wide-Area Augmentation System (WAAS) was designed to enhance the GNSS standard positioning service by providing additional accuracy, availability and integrity that is sufficient for use in commercial aviation. It is the first of a number of planned regional Satellite Based Augmentation Systems (SBAS). Other systems in development include the European EGNOS system, the MSAS system in Japan and the GAGAN system in India. In addition, the South American countries are investigating the feasibility of operating an SBAS system in this region. Much of the WAAS ionospheric research and development focused on defining and mitigating ionospheric challenges characteristic of the mid-latitude regions, where the ionosphere is well studied and relatively quiescent. The EGNOS and MSAS systems will primarily operate under a similarly quiescent mid-latitude ionosphere. SBAS system development in South America, India and other low-latitude regions, however, will have to contend with much more extreme conditions. These conditions include strong spatial and temporal gradients, plasma depletions and scintillation. All of these conditions have a potential to limit SBAS performance in the low latitude regions. This presentation will review the effects that the ionosphere has on the mid-latitude WAAS system. It will present the techniques that are used to mitigate ionospheric disturbances induced on the system during severe geomagnetic activity and it will quantify the effect that this activity has on system performance. The presentation will then present data from the South American Low-latitude Ionospheric Sensor Network (LISN) that can be used to infer the ionospheric effects on SBAS performance in the most challenging low-latitude ionospheric environment

  15. The theory of ionospheric focused heating

    NASA Technical Reports Server (NTRS)

    Bernhardt, P. A.; Duncan, L. M.

    1987-01-01

    Ionospheric modification by high power radio waves and by chemical releases are combined in a theoretical study of ionospheric focused heating. The release of materials which promote electron-ion recombination creates a hole in the bottomside ionosphere. The ionospheric hole focuses high power radio waves from a ground-based transmitter to give a 20 dB or greater enhancement in power density. The intense radio beam excites atomic oxygen by collisions with accelerated electrons. Airglow from the excited oxygen provides a visible trace of the focused beam. The large increase in the intensity of the radio beam stimulates new wave-plasma interactions. Numerical simulations show that the threshold for the two-plasmon decay instability is exceeded. The interaction of the pump electromagnetic wave with the backward plasmon produces a scattered electromagnetic wave at 3/2 the pump frequency. The scattered wave provides a unique signature of the two-plasmon decay process for ground-based detection.

  16. Ionospheric redistribution during geomagnetic storms

    PubMed Central

    Immel, T J; Mannucci, A J

    2013-01-01

    [1]The abundance of plasma in the daytime ionosphere is often seen to grow greatly during geomagnetic storms. Recent reports suggest that the magnitude of the plasma density enhancement depends on the UT of storm onset. This possibility is investigated over a 7year period using global maps of ionospheric total electron content (TEC) produced at the Jet Propulsion Laboratory. The analysis confirms that the American sector exhibits, on average, larger storm time enhancement in ionospheric plasma content, up to 50% in the afternoon middle-latitude region and 30% in the vicinity of the high-latitude auroral cusp, with largest effect in the Southern Hemisphere. We investigate whether this effect is related to the magnitude of the causative magnetic storms. Using the same advanced Dst index employed to sort the TEC maps into quiet and active (Dst<−100 nT) sets, we find variation in storm strength that corresponds closely to the TEC variation but follows it by 3–6h. For this and other reasons detailed in this report, we conclude that the UT-dependent peak in storm time TEC is likely not related to the magnitude of external storm time forcing but more likely attributable to phenomena such as the low magnetic field in the South American region. The large Dst variation suggests a possible system-level effect of the observed variation in ionospheric storm response on the measured strength of the terrestrial ring current, possibly connected through UT-dependent modulation of ion outflow. PMID:26167429

  17. The plasma environment of Uranus

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Mcnutt, R. L., Jr.; Richardson, J. D.; Selesnick, R. S.; Sittler, E. C., Jr.; Bagenal, F.

    1991-01-01

    An overview of the observational results on the plasma environment at Uranus is given, and the implications of these observations for magnetospheric physics at Uranus are discussed. During the Voyager 2 encounter with Uranus, an extended magnetosphere filled with a tenuous plasma was detected. This low-energy plasma was found to consist of protons and electrons, with no significant heavy ion contribution, and with a density in the regions sampled by the spacecraft of at most three electrons per cubic centimeter. The plasma electrons and ions exhibit both a thermal component (with temperatures of tens of eV) and a hot component (with temperatures of a few keV). The thermal ion component is observed both inside and outside an L-shell value near 5, whereas the hot ion and electron component is excluded from the region inside of that L-shell. The source of the thermal component of the plasma is either the planetary ionosphere or the neutral hydrogen corona surrounding Uranus, whereas the hot component is convected in from the magnetotail, with probably an ionospheric source.

  18. Photochemistry of planetary ionospheres

    NASA Technical Reports Server (NTRS)

    Nagy, Andrew F.

    1987-01-01

    The dominant photochemical reactions taking place in the ionospheres of Venus, Saturn, and Comet P/Halley are presented. It is shown that the differences in the ionospheres of these celestial bodies result from the different chemistry, energetics, and dynamics of the respective atmospheres. The role of photochemistry in the formation of the individual ionospheres is discussed.

  19. Ionospheric Cubeswarm Concept Study: using low-resource instrumentation for truly multipoint in situ ionospheric observations

    NASA Astrophysics Data System (ADS)

    Hampton, D.; Lynch, K. A.; Earle, G. D.; Mannucci, A. J.; Clayton, R.; Fisher, L. E.; Fernandes, P. A.; Roberts, M.; Zettergren, M. D.

    2015-12-01

    Magnetosphere-ionosphere coupling currents close in the nightside lower ionosphere. These spatially inhomogeneous and time varying volume currents are difficult to capture with in situ observations. Our understanding of M-I coupling systems is limited by our understanding of the actual structure of ionospheric current closure. A path forward includes assimilation of a variety of data sets into increasingly capable ionospheric models. While each data set provides only a piece of the picture, the assimilation process allows optimal use of each piece.An important development for the necessary in situ observations involves making them truly multi-point, and therefore, low-resource. For thermal particle observations, the high densities of the lower ionosphere allow the use of low-gain (current-sensing rather than particle-counting) particle sensors. One observational goal is the definition of the actual structure of ionospheric closure currents. This can be approached with a number of different measurement techniques, in tandem with an ionospheric model, since the closure currents need to follow the rules of electrodynamics and current continuity. Low resource thermal plasma sensors such as retarding potential analyzers and drift meters can provide valuable measurements of plasma parameters, including density and plasma flow, without the need for high voltages or deployable boom systems. These low-resource measurements, which can be reproduced on arrays of in situ observation platforms, used in tandem with proper plasma physics interpretation of their signatures in the disturbed observing environment, and as part of an assimilated data set into an ionospheric model, can allow us to progress in our understanding of ionospheric structuring and its effects on auroral coupling. Now, with increasingly capable multipoint arrays of spacecraft, and quantitative 2D-with-time context from cameras and imagery, we are moving toward truly multipoint studies of the system

  20. Probe experiment for measurement of plasma parameters and ion drift velocities in the ionospheric plasma onboard the Intercosmos-Bulgaria 1300 satellite

    NASA Astrophysics Data System (ADS)

    Serafimov, K.; Bankov, L.; Gusheva, M.; Ivanova, T.; Markov, V.; Chapkunov, S.; Kutiev, I.; Genov, V.

    In agreement with the scientific program Bulgaria-1300, a complex of probe instruments was designed for the measurements equipment: ID-1, P-6, P-7 and DIET-2 to define the local plasma parameters. The instruments measure: electron temperature Te, electron density Ne, ion temperature Ti, ion density Ni, ion energy distribution f(E j), mass ion composition Mi, complete ion drift vector V D 0.1 to 5 km/s and ion density variations ΔN j/N j within the range 0.50-100%.

  1. Patches in the polar ionosphere: UT and seasonal dependence

    SciTech Connect

    Sojka, J.J.; Bowline, M.D.; Schunk, R.W.

    1994-08-01

    The seasonal and UT dependencies of patches in the polar ionosphere are simulated using the Utah State University time dependent ionospheric model (TDIM). Patch formation is achieved by changing the plasma convection pattern in response to temporal changes in the interplanetary magnetic field (IMF) B{sub y} component during periods of southward IMF. This mechanism redirects the plasma flow from the dayside high-density region, which is the source of the tongue of ionization (TOI) density feature, through the throat and leads to patches, rather than a continuous TOI. The model predicts that the patches are absent at winter solstice (northern hemisphere) between 0800 and 1200 UT and that they have their largest seasonal intensity at winter solstice between 2000 and 2400 UT. Between winter solstice and equinox, patches are strong and present all day. Patches are present in summer as well, although their intensity is only tens of percent above the background density. These winter-to-equinox findings are also shown to be consistent with observations. The model was also used to predict times at which patch observations could be performed to determine the contributions from other patch mechanisms. This observational window is {+-} 20 days about winter solstice between 0800 and 1200 UT in the northern hemisphere. In this observational window the TOI is either absent or reduced to a very low density. Hence the time dependent electric field mechanism considered in this study does not produce patches, and if they are observed, then they must be due to some other mechanism. 32 refs., 10 figs.

  2. HAARP-Induced Ionospheric Ducts

    SciTech Connect

    Milikh, Gennady; Vartanyan, Aram

    2011-01-04

    It is well known that strong electron heating by a powerful HF-facility can lead to the formation of electron and ion density perturbations that stretch along the magnetic field line. Those density perturbations can serve as ducts for ELF waves, both of natural and artificial origin. This paper presents observations of the plasma density perturbations caused by the HF-heating of the ionosphere by the HAARP facility. The low orbit satellite DEMETER was used as a diagnostic tool to measure the electron and ion temperature and density along the satellite orbit overflying close to the magnetic zenith of the HF-heater. Those observations will be then checked against the theoretical model of duct formation due to HF-heating of the ionosphere. The model is based on the modified SAMI2 code, and is validated by comparison with well documented experiments.

  3. Ionospheric heating, upwelling, and depletions in auroral current systems

    NASA Astrophysics Data System (ADS)

    Zettergren, M. D.; Semeter, J. L.

    2010-12-01

    This research investigates aspects of ionospheric dynamics relevant to magnetosphere-ionosphere coupling in auroral arc current systems. Auroral electric fields and particle precipitation deposit energy in the ionosphere, often resulting in enhanced ion or electron temperatures. This heating has a wide variety of consequences for the ionosphere. High ion temperatures alter chemical balance in the lower F-region, resulting in conversion to a molecular ion plasma, faster recombination, and plasma depletions. Pressure enhancements resulting from both ion and electron heating are capable of generating intense ion upflows. Ion upflow and depletion processes redistribute and structure the auroral plasma in ways that are likely of consequence to wave coupling of the magnetosphere and ionosphere. These implications are examined through the use of a fluid-kinetic model of the auroral ionosphere and new incoherent scatter radar data analysis techniques. Results indicate that enhanced recombination of molecular ions in auroral downward current regions may work in concert with well-known electrodynamic depletion processes, in the F-region ionosphere. Furthermore, ionospheric upflows in auroral upward and downward current regions may be quite different in terms of intensity and types of upflowing ions.

  4. Global Dayside Ionospheric Uplift and Enhancement Associated with Interplanetary Electric Fields

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce; Mannucci, Anthony; Iijima, Byron; Abdu, Mangalathayil Ali; Sobral, Jose Humberto A.; Gonzalez, Walter; Guarnieri, Fernando; Tsuda, Toshitaka; Saito, Akinori; Yumoto, Kiyohumi; Fejer, Bela; Fuller-Rowell, Timothy J.; Kozyra, Janet; Foster, John C.; Coster, Anthea; Vasyliunas, Vytenis M.

    2004-01-01

    The interplanetary shock/electric field event of 5-6 November 2001 is analyzed using ACE interplanetary data. The consequential ionospheric effects are studied using GPS receiver data from the CHAMP and SAC-C satellites and altimeter data from the TOPEX/ Poseidon satellite. Data from 100 ground-based GPS receivers as well as Brazilian Digisonde and Pacific sector magnetometer data are also used. The dawn-to-dusk interplanetary electric field was initially 33 mV/m just after the forward shock (IMF BZ = -48 nT) and later reached a peak value of 54 mV/m 1 hour and 40 min later (BZ = -78 nT). The electric field was 45 mV/m (BZ = -65 nT) 2 hours after the shock. This electric field generated a magnetic storm of intensity DST = -275 nT. The dayside satellite GPS receiver data plus ground-based GPS data indicate that the entire equatorial and midlatitude (up to +/-50(deg) magnetic latitude (MLAT)) dayside ionosphere was uplifted, significantly increasing the electron content (and densities) at altitudes greater than 430 km (CHAMP orbital altitude). This uplift peaked 2 1/2 hours after the shock passage. The effect of the uplift on the ionospheric total electron content (TEC) lasted for 4 to 5 hours. Our hypothesis is that the interplanetary electric field ''promptly penetrated'' to the ionosphere, and the dayside plasma was convected (by E x B) to higher altitudes. Plasma upward transport/convergence led to a 55-60% increase in equatorial ionospheric TEC to values above 430 km (at 1930 LT). This transport/convergence plus photoionization of atmospheric neutrals at lower altitudes caused a 21% TEC increase in equatorial ionospheric TEC at 1400 LT (from ground-based measurements). During the intense electric field interval, there was a sharp plasma ''shoulder'' detected at midlatitudes by the GPS receiver and altimeter satellites. This shoulder moves equatorward from -54(deg) to -37(deg) MLAT during the development of the main phase of the magnetic storm. We presume this to

  5. Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System: A UnifiedApproach for Studying Hot and Cold Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Karimabadi, H.; Omelchenko, Y.; Schunk, R. W.; Barakat, A. R.; Gardner, L. C.; Khazanov, G. V.; Glocer, A.; Kistler, L. M.

    2013-12-01

    The Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System is complex; it varies on a wide range in spatial and temporal scales, exhibits relatively thin ion-scale boundaries (e.g., bow shock, magnetopause, magnetotail), contains hot and cold particle populations, and the particle distribution functions are typically non-Maxwellian. The existing space weather frameworks are based on global fluid models and therefore cannot address many important issues concerning particle, momentum, and energy coupling in the system. To remedy this situation, we have formed a multi-disciplinary team to create a new kinetic modeling framework. The new framework will include kinetic electron and ion formulations for the ionosphere, plasmasphere, and polar wind domains, and kinetic ions and fluid electrons for the magnetosphere. The proposed methodology is expected to lead to breakthroughs in studying numerous problems/issues, including the self-consistent formation of the ring current, the self-consistent formation of ion scale turbulence and waves, the calculation of appropriate reconnection rates, the effect that multiple species and ion outflows from the ionosphere have on the development and evolution of storms/substorms, among others. The presentation will focus on the current state and capabilities of the global kinetic models that form the framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind Model.

  6. Multi-instrument observations of plasma features in the Arctic ionosphere during the main phase of a geomagnetic storm in December 2006

    NASA Astrophysics Data System (ADS)

    Wu, Ye-wen; Liu, Rui-yuan; Zhang, Bei-chen; Wu, Zhen-sen; Hu, Hong-qiao; Zhang, Shun-rong; Zhang, Qing-he; Liu, Jun-ming; Honary, F.

    2013-12-01

    Arctic ionospheric variations during the main phase of a magnetic storm on 14-15 December, 2006 were investigated to characterize the high energy particle precipitation caused effects, based on multi-instrument observations. These include electron density observations provided by the Global Positioning System (GPS) total electron content (TEC) measurements, European Incoherent Scatter (EISCAT) radar, the radio occultation (RO) from both the CHAMP satellite and the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite, as well as the ionospheric absorption of cosmic radio noise measured by the Imaging Riometer for Ionospheric Studies (IRIS) at Kilpisjärvi in the northern Finland (69.05°N, 20.79°E). Significant increases in the electron density for these different observations were found in the Arctic ionosphere during the main phase of the magnetic storm. These increase occurred in Scandinavian, Northwest part of Russia and Svalbard (SNRS) region, primarily at an altitude of about 110 km. These results are first reported for the SNRS region, and our study contributes to a more complete description of this space weather event during 14-15 December, 2006. Our observations also provide direct evidence that the stormtime E-layer electron density enhancement (e.g., the sporadic E) can form a nearly dominant portion in the observed TEC increase. These increases were accompanied by the ionospheric absorption enhancement at the altitude of about 90 km. The Y-component of magnetic field to the south of SNRS decreased, indicating strong upward field aligned electric current in the Arctic ionosphere. These features are interpreted as the effect of the high energy electron precipitation during the magnetic storm, which is caused by the sub-storm reflected on AL index and the measurements of IMAGE (International Monitor for Auroral Geomagnetic Effects) chain. The average energy of the precipitation electrons reached to about 10 keV and the

  7. Electrodynamics of the equatorial evening ionosphere: 1. Importance of winds in different regions

    NASA Astrophysics Data System (ADS)

    Richmond, A. D.; Fang, T.-W.; Maute, A.

    2015-03-01

    The importance of winds at different altitudes and latitudes for the electrodynamics of the low-latitude evening ionosphere is examined with a model of the global coupled ionosphere-thermosphere system. The model reproduces the main observed features of the evening equatorial plasma vortex and the prereversal enhancement (PRE) of the vertical drift. The electrodynamics is driven primarily by the zonal wind forced by the diurnally varying zonal pressure-gradient force. The zonal wind lags the zonal pressure-gradient force owing to inertia. When ion drag is important, the time lag of the wind behind the pressure gradient force is shortened, and the high-altitude evening wind turns eastward earlier than the wind at lower altitudes, where ion drag is less important. Therefore, a vertical shear of the zonal wind tends to develop at altitudes around the transition between small and large ion drag at the bottom of the F region. This wind shear is closely associated with the vertical shear in the zonal convection velocity that is part of the evening plasma vortex. Unlike previous studies, we find that the winds driving the PRE lie mainly on field lines with apexes above the peak of the equatorial F layer, field lines that extend in magnetic latitude out to nearly 30° and encompass the entire evening equatorial ionization anomaly region. Contrary to previous suggestions, the westward convection in the bottomside of the evening plasma vortex is found to weaken, rather than strengthen, the PRE. Daytime winds have relatively little influence on the low-latitude evening electrodynamics.

  8. Convective radial energy flux due to resonant magnetic perturbations and magnetic curvature at the tokamak plasma edge

    SciTech Connect

    Marcus, F. A.; Beyer, P.; Fuhr, G.; Monnier, A.; Benkadda, S.

    2014-08-15

    With the resonant magnetic perturbations (RMPs) consolidating as an important tool to control the transport barrier relaxation, the mechanism on how they work is still a subject to be clearly understood. In this work, we investigate the equilibrium states in the presence of RMPs for a reduced MHD model using 3D electromagnetic fluid numerical code with a single harmonic RMP (single magnetic island chain) and multiple harmonics RMPs in cylindrical and toroidal geometry. Two different equilibrium states were found in the presence of the RMPs with different characteristics for each of the geometries used. For the cylindrical geometry in the presence of a single RMP, the equilibrium state is characterized by a strong convective radial thermal flux and the generation of a mean poloidal velocity shear. In contrast, for toroidal geometry, the thermal flux is dominated by the magnetic flutter. For multiple RMPs, the high amplitude of the convective flux and poloidal rotation are basically the same in cylindrical geometry, but in toroidal geometry the convective thermal flux and the poloidal rotation appear only with the islands overlapping of the linear coupling between neighbouring poloidal wavenumbers m, m – 1, and m + 1.

  9. The lower ionosphere at high latitudes

    NASA Astrophysics Data System (ADS)

    Schunk, R. W.; Sojka, J. J.

    The lower ionosphere is a particularly difficult region to both observe and model. Although radars and rockets have probed this region for more than two decades, our overall understanding of the interplay between radiative, chemical, dynamical, and electrodynamical processes in the lower ionosphere is relatively poor in comparison to the other regions of the solar-terrestrial system. Part of the problem is that the various radar and rocket campaigns have focused on different scientific issues, have been of limited duration, or have been restricted to specific geographical locations. However, the lower ionosphere is a complex region, being acted upon by magnetospheric processes from above and stratospheric processes from below. Within the lower ionosphere are chemical reactions involving negative, positive, and cluster ions; transport processes that sometimes involve ordinary diffusion, turbulence, and wave-particle interactions due to plasma instabilities; radiative processes that could involve multiple scattering effects; and energetics that could result in non-Maxwellian ion velocity distribution functions. A further complication arises in that the processes acting on and within the lower ionosphere do so on widely different spatial and temporal scales, and these scales are directly reproduced in the medium. An overview of our current knowledge of the lower ionosphere is presented in this brief review, with the emphasis on the high latitude region.

  10. Tropical Cyclone - Equatorial Ionosphere Coupling: A Statistical Study

    NASA Astrophysics Data System (ADS)

    Bhagavathiammal, G. J.

    2016-07-01

    This paper describes the equatorial ionosphere response to tropical cyclone events which was observed over the Indian Ocean. This statistical study tries to reveal the possible Tropical Cyclone (TC) - Ionosphere coupling. Tropical cyclone track and data can be obtained from the India Meteorological Department, New Delhi. Digisonde/Ionosonde data for the equatorial latitudes can be obtained from Global Ionospheric Radio Observatory. It is believed that TC induced convection as the driving agent for the increased gravity wave activity in the lower atmosphere and these propagating gravity waves deposit their energy and momentum into the upper atmosphere as Travelling Ionospheric Disturbances (TIDs). The convective regions are identified with the help of Outgoing Long wave radiation (OLR) data from NOAA Climate Data Center/ Precipitation data from TRMM Statellite. The variability of ionospheric parameter like Total Electron Content (TEC), foF2, h'F2 and Drift velocity are examined during TC periods. This study will report the possibility of TC-Ionosphere Coupling in equatorial atmosphere.

  11. Dynamics of American Sector Mid and Low Latitude Ionospheric and Thermospheric Response During the November 2004 Superstorm

    NASA Astrophysics Data System (ADS)

    Erickson, P. J.; Goncharenko, L. P.; Nicolls, M. J.; Crowley, G.; Kelley, M. C.

    2007-12-01

    Interplanetary electric field (IEF) penetration into the inner magnetosphere and plasmasphere can occur during intense geomagnetic storms, enhancing eastward electric fields over the sunlit ionosphere. Such events can serve as triggers for complex ionosphere-magnetosphere feedback mechanisms which increase ionospheric convection and neutral winds both locally and globally. We present a study of ionospheric dynamics and physical drivers during several events contained within the November 9 - 11, 2004 superstorm. This event was marked by excellent coverage from the full American sector incoherent scatter radar chain at Jicamarca, Arecibo, Millstone Hill, and Sondrestrom, which allows wide latitude diagnostics of E and F region electric fields, plasma densities and temperatures, and neutral wind vectors. We also employ CARISMA magnetometer chain observations, DMSP SSIES topside ion drifts, and GPS derived total electron content (TEC) maps to place the radar data in context. Penetrating eastward electric fields were seen from Millstone Hill equatorwards to Jicamarca for over 15 hours on November 9 and 10, accompanied by very low TEC values and a plasmasphere boundary layer midway between Millstone Hill and Arecibo. Equatorward neutral wind surges of ~ 300 m/s were driven locally by substorms at Millstone Hill and Arecibo, with associated dynamo effects creating prompt electric fields and large F layer downdrafts. Substorm timing during three separate events as identified from CARISMA magnetometers is consistent with Millstone Hill observed neutral wind surges. We also present results from TIMEGCM model runs and compare predictions of ionospheric conditions along the radar chain to gain insight into the complex physical drivers during this superstorm event.

  12. A modeling study of asymmetries in plasma irregularity characteristics near gradient reversals

    NASA Astrophysics Data System (ADS)

    Lamarche, Leslie J.; Makarevich, Roman A.

    2016-08-01

    Asymmetries in plasma density irregularity generation between the leading and trailing edges of the large-scale plasma density structures in the high-latitude ionosphere are investigated. A model is developed that evaluates the gradient-drift instability (GDI) growth rate differences across the gradient reversal that is applicable at all propagation directions and for the broad range of altitudes spanning the entire lower ionosphere. In particular, the model describes asymmetries that would be observed by an oblique scanning radar near density structures in the polar cap such as elongated polar patches. The dependencies on the relative orientations between the directions of the gradient reversal, plasma convection, and wave propagation are examined at different altitudinal regions. At all altitudes, the largest asymmetries are expected for observations along the gradient reversals, e.g., when an elongated structure is oriented along the radar boresight. The convection direction that results in the strongest asymmetries exhibits a strong dependence on the altitude, with the optimal convection being parallel to the gradient reversal in the E region, perpendicular to it in the F region, and at some angle between these extremes in the transitional region. Implications for observations of polar patches by oblique scanning radars within the Super Dual Auroral Radar Network are discussed. It is demonstrated that the wave propagation direction relative to the prevalent convection and gradient directions plays a critical role in controlling both the irregularity growth rate and its asymmetries near gradient reversals.

  13. Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event

    NASA Astrophysics Data System (ADS)

    McWilliams, K. A.; Yeoman, T. K.; Cowley, S. W. H.

    2000-12-01

    Line-of-sight Doppler velocities from the SuperDARN CUTLASS HF radar pair have been combined to produce the first two-dimensional vector measurements of the convection pattern throughout the ionospheric footprint of a flux transfer event (a pulsed ionospheric flow, or PIF). Very stable and moderate interplanetary magnetic field conditions, along with a preceding prolonged period of northward interplanetary magnetic field, allow a detailed study of the spatial and the temporal evolution of the ionospheric response to magnetic reconnection. The flux tube footprint is tracked for half an hour across six hours of local time in the auroral zone, from magnetic local noon to dusk. The motion of the footprint of the newly reconnected flux tube is compared with the ionospheric convection velocity. Two primary intervals in the PIF's evolution have been determined. For the first half of its lifetime in the radar field of view the phase speed of the PIF is highly variable and the mean speed is nearly twice the ionospheric convection speed. For the final half of its lifetime the phase velocity becomes much less variable and slows down to the ionospheric convection velocity. The evolution of the flux tube in the magnetosphere has been studied using magnetic field, magnetopause and magnetosheath models. The data are consistent with an interval of azimuthally propagating magnetopause reconnection, in a manner consonant with a peeling of magnetic flux from the magnetopause, followed by an interval of anti-sunward convection of reconnected flux tubes.

  14. Magnetosphere-Ionosphere Coupling Processes in the Ionospheric Trough Region During Substorms

    NASA Astrophysics Data System (ADS)

    Zou, S.; Moldwin, M.; Nicolls, M. J.; Ridley, A. J.; Coster, A. J.; Yizengaw, E.; Lyons, L. R.; Donovan, E.

    2013-12-01

    The ionospheric troughs are regions of remarkable electron density depression at the subauroral and auroral latitudes, and are categorized into the mid-latitude trough or high-latitude trough, depending on their relative location to the auroral oval. Substorms are one fundamental element of geomagnetic activity, during which structured field-aligned currents (FACs) and convection flows develop in the subauroral and auroral ionosphere. The auroral/trough region is expected to experience severe electron density variations during substorms. Accurate specification of the trough dynamics during substorms and understanding its relationship with the structured FACs and convection flows are of important practical purpose, including providing observational foundations for assessing the attendant impact on navigation and communication. In addition, troughs are important since they map to magnetospheric boundaries allowing the remote sensing of magnetosphere-ionosphere coupling processes. In this talk, we discuss the dynamics of the mid-latitude and high-latitude troughs during substorms based on multi-instrument observations. Using GPS total electron content (TEC) data, we characterize the location and width of the mid-latitude trough through the substorm lifecycle and compare them with existing trough empirical models. Using a combination of incoherent scattering radar (ISR), GPS TEC, auroral imager and a data assimilative model, we investigate the relationship between the high-latitude trough and FACs as well as convection flows. The high-latitude trough is found to be collocated with a counter-clockwise convection flow vortex east of the Harang reversal region, and downward FACs as part of the substorm current system are suggested to be responsible for the high-latitude trough formation. In addition, complex ionospheric electron temperature within the high-latitude trough is found, i.e., increase in the E region while decrease in the F region. We discuss possible

  15. Solar flare soft-X-ray spectra from Very Low Frequency observations of ionospheric modulations: Possibility of uninterrupted observation of non-thermal electron-plasma interaction in solar atmosphere.

    NASA Astrophysics Data System (ADS)

    Palit, Sourav; Chakrabarti, Sandip Kumar; Ray, Suman

    2016-07-01

    The hard and soft X-ray regions of a solar flare spectrum are the manifestation of interaction, namely of bremsstrahlung radiation of the non-thermal electrons moving inward in the denser part of the solar atmosphere with the plasma heated by those energetic electrons. The continuous and uninterrupted knowledge of X-ray photon spectra of flares are of great importance to derive information on the electron acceleration and hence time-evolution of energy transport and physics during solar flares. Satellite observations of solar X-ray spectrum are often limited by the restricted windows in each duty cycle to avoid the interaction of detectors and instruments with harmful energetic charge particles. In this work we have tried to tackle the problem by examining the possibility of using Earth's ionosphere and atmosphere as the detector of such transient events. Earth's lower ionosphere and upper atmosphere are the places where the X-rays and gamma-rays from such astronomical sources are absorbed. The electron-ion production rates due to the ionization of such energetic photons at different heights depend on the intensity and wavelength of the injected spectra and hence vary from one source to another. Obviously the electron and ion density vs. altitude profile has the imprint of the incident photon spectrum. As a preliminary exercise we developed a novel deconvolution method to extract the soft X-ray part of spectra of some solar flares of different classes from the electron density profiles obtained from Very Low Frequency (VLF) observation of lower ionosphere during those events. The method presented here is useful to carry out a similar exercise to infer the higher energy part of solar flare spectra and spectra of more energetic events such as the GRBs, SGRs etc. with the possibilities of probing even lower parts of the atmosphere.

  16. Solar wind interaction with the ionosphere of Venus inferred from radio scintillation measurements

    NASA Technical Reports Server (NTRS)

    Woo, Richard; Sjogren, William L.; Kliore, Arvydas J.; Luhmann, Janet G.; Brace, Larry H.

    1989-01-01

    The observation of S-band (2.3 GHz) radio scintillations in the ionosphere of Venus by the Pioneer Venus Orbiter is reported. In situ plasma measurements and propagation calculations show that the scintillations are caused by electron density irregularities in the topside ionosphere of Venus below the ionopause. It is suggested that these topside plasma irregularities are associated with the penetration of large-scale magnetic fields in the ionosphere. It is found that the disturbed plasma and the scintillations are a manifestation of high-dynamic solar wind interaction with the ionosphere.

  17. Solar wind interaction with the ionosphere of Venus inferred from radio scintillation measurements

    NASA Astrophysics Data System (ADS)

    Woo, R.; Sjogren, W. L.; Luhmann, J. G.; Kliore, A. J.; Brace, L. H.

    1989-02-01

    The observation of S-band (2.3 GHz) radio scintillations in the ionosphere of Venus by the Pioneer Venus Orbiter is reported. In situ plasma measurements and propagation calculations show that the scintillations are caused by electron density irregularities in the topside ionosphere of Venus below the ionopause. It is suggested that these topside plasma irregularities are associated with the penetration of large-scale magnetic fields in the ionosphere. It is found that the disturbed plasma and the scintillations are a manifestation of high-dynamic solar wind interaction with the ionosphere.

  18. Ionospheric research opportunity

    NASA Astrophysics Data System (ADS)

    Rickel, Dwight

    1985-05-01

    Ground-based explosions have been exploited successfully in the past as a relatively controlled source for producing ionospheric disturbances. On June 25, the Defense Nuclear Agency will conduct a high explosives test on the northern section of the White Sands Missile Range. Approximately 4,800 tons of ammonium nitrate and fuel oil (ANFO) will be detonated at ground level, producing an acoustic shock wave with a surface pressure change of approximately 20 mbar at a 6 km range. This shock front will have sufficient strength to propagate into the ionosphere with at least a 10% change in the ambient pressure across the disturbance front in the lower F region. Such an ionospheric perturbation will give ionospheric researchers an excellent opportunity to investigate acoustic propagation at ionospheric heights, shock dissipation effect, the ion-neutral coupling process, acoustic-gravity wave (traveling ionospheric disturbance) generation mechanisms, and associated RF phenomena.

  19. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    SciTech Connect

    Lay, Erin H.; Shao, Xuan -Min; Kendrick, Alexander K.; Carrano, Charles S.

    2015-07-30

    Acoustic waves with periods of 2–4 min and gravity waves with periods of 6–16 min have been detected at ionospheric heights (25–350 km) using GPS total electron content measurements. The area disturbed by these waves and the wave amplitudes have been associated with underlying thunderstorm activity. A statistical study comparing Next Generation Weather Radar thunderstorm measurements with ionospheric acoustic and gravity waves in the midlatitude U.S. Great Plains region was performed for the time period of May–July 2005. An increase of ionospheric acoustic wave disturbed area and amplitude is primarily associated with large thunderstorms (mesoscale convective systems). Ionospheric gravity wave disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.

  20. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    DOE PAGES

    Lay, Erin H.; Shao, Xuan -Min; Kendrick, Alexander K.; Carrano, Charles S.

    2015-07-30

    Acoustic waves with periods of 2–4 min and gravity waves with periods of 6–16 min have been detected at ionospheric heights (25–350 km) using GPS total electron content measurements. The area disturbed by these waves and the wave amplitudes have been associated with underlying thunderstorm activity. A statistical study comparing Next Generation Weather Radar thunderstorm measurements with ionospheric acoustic and gravity waves in the midlatitude U.S. Great Plains region was performed for the time period of May–July 2005. An increase of ionospheric acoustic wave disturbed area and amplitude is primarily associated with large thunderstorms (mesoscale convective systems). Ionospheric gravity wavemore » disturbed area and amplitude scale with thunderstorm activity, with even small storms (i.e., individual storm cells) producing an increase of gravity waves.« less

  1. The plasma environment, charge state, and currents of Saturn's C and D rings

    SciTech Connect

    Wilson, G.R. )

    1991-06-01

    The plasma environment of the Saturnian C and D rings is investigated by modeling the flow of ionospheric plasma from the mid- to low-latitude ionosphere to the vicinity of the rings. The model used is time-dependent and kinetic and incorporates the gravitational, centripetal, magnetic mirror and ambipolar electric forces. It was found that the plasma density near the C and D rings, at a given radial location, will experience a one to two order of magnitude diurnal variation. With a knowledge of the plasma density and temperature near these rings their charge state is investigated by use of a dust cloud charging model. The associated azimuthal currents are also found. Results show that the surface charge density of the C and D rings can show significant radial and azimuthal variations, due mainly to variations in the plasma density. In addition to its plasma density and temperature dependence the surface charge density will also depend on structural features of the rings such as the ring thickness and the nature of the particle size distribution. Its magnitude may vary over seven decades. The associated azimuthal currents carried by these rings will also show large diurnal variations resulting in field-aligned currents which close in the ionosphere as shown by Ip and Mendis (1983). However, the resulting ionospheric electric fields will probably not produce a significant amount of plasma convection in the topside ionosphere and inner plasmasphere as proposed by these authors, due in part to the level of the currents as well as the height-integrated Pedersen conductivities at the local times where the currents close.

  2. Observational Evidence that Magnetosheath Plasma Parameters are Prominent in Determining Cross Polar Cap Potential Saturation

    NASA Astrophysics Data System (ADS)

    Clauer, Robert; Xu, Zhonghua; Hartinger, Michael; Ruohoniemi, Michael; Scales, Wayne; Maimaiti, Maimaitirebike; Nicolls, Michael; Wilder, Rick; Lopez, Ramon

    2016-04-01

    A variety of statistical studies have shown that the ionospheric polar potential produced by solar wind - magnetosphere - ionosphere coupling is linear for weak to moderate solar wind driving, but becomes non-linear during periods of very strong driving. It has been shown that this applies to the two-cell convection potential that develops during southward interplanetary magnetic field (IMF) and also to the reverse convection cells that develop during northward IMF. This has been described as polar potential saturation and it appears to begin when the driving solar wind electric field becomes greater than 3 mV/m. It has also been shown that the summer ionospheric electric field saturates at about the same value (20 mV/m) for both northward or southward IMF. Recent measurements of the high latitude convection on September 12 - 13, 2014 using the Resolute Incoherent Scatter Radar during periods of large northward IMF show ionospheric electric fields varying between 56 mV/m and 156 mV/m within the dayside reverse convection cells. There is no indication of saturation during these periods of very strong driving. We believe that the extremely rare conditions in the solar wind that produce extreme driving while also producing a high plasma beta in the magnetosheath provide the best explanation for the lack of potential saturation of the reverse convection cells. That is to say, the conditions in the magnetosheath that contribute to enhancing or limiting reconnection are most important in determining cross polar cap potential saturation. This research was supported at Virginia Tech by National Science Foundation Grant AGS-1216373.

  3. Imaging the topside ionosphere and plasmasphere with ionospheric tomography using COSMIC GPS TEC

    NASA Astrophysics Data System (ADS)

    Pinto Jayawardena, Talini S.; Chartier, Alex T.; Spencer, Paul; Mitchell, Cathryn N.

    2016-01-01

    GPS-based ionospheric tomography is a well-known technique for imaging the total electron content (TEC) between GPS satellites and receivers. However, as an integral measurement of electron concentration, TEC typically encompasses both the ionosphere and plasmasphere, masking signatures from the topside ionosphere-plasmasphere due to the dominant ionosphere. Imaging these regions requires a technique that isolates TEC in the topside ionosphere-plasmasphere. Multi-Instrument Data Analysis System (MIDAS) employs tomography to image the electron distribution in the ionosphere. Its implementation for regions beyond is yet to be seen due to the different dynamics present above the ionosphere. This paper discusses the extension of MIDAS to image these altitudes using GPS phase-based TEC measurements and follows the work by Spencer and Mitchell (2011). Plasma is constrained to dipole field lines described by Euler potentials, resulting in a distribution symmetrical about the geomagnetic equator. A simulation of an empirical plasmaspheric model by Gallagher et al. (1988) is used to verify the technique by comparing reconstructions of the simulation with the empirical model. The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) is used as GPS receiver locations. The verification is followed by a validation of the modified MIDAS algorithm, where the regions' TEC is reconstructed from COSMIC GPS phase measurements and qualitatively compared with previous studies using Jason-1 and COSMIC data. Results show that MIDAS can successfully image features/trends of the topside ionosphere-plasmasphere observed in other studies, with deviations in absolute TEC attributed to differences in data set properties and the resolution of the images.

  4. Time dependent response of equatorial ionospheric electric fields to magnetospheric disturbances

    SciTech Connect

    Fejer, B.G.; Scherliess, L.

    1995-04-01

    The authors use extensive radar measurements of F region vertical plasma drifts and auroral electrojet indices to determine the storm time dependence of equatorial zonal electric fields. These disturbance drifts result from the prompt penetration of high latitude electric fields and from the dynamo action of storm time winds which produce the largest perturbations a few hours after the onset of magnetic activity. The signatures of the equatorial disturbance electric fields change significantly depending on the relative contributions of these two components. The prompt electric field responses, with lifetimes of about one hour, are in excellent agreement with results from global convection models. The electric fields generated by storm time winds have longer lifetimes, amplitudes proportional to the energy input into the high latitude ionosphere, and a daily variation which follows closely the disturbance dynamo pattern of Blanc and Richmond. The storm wind driven electric fields are responsible for the larger amplitudes and longer lifetimes of the drift perturbations following sudden decreases in convection compared to those associated with sudden convection enhancements. 14 refs., 6 figs., 1 tab.

  5. Convergent instability in the ionosphere

    SciTech Connect

    Ponyatov, A.A.

    1994-04-01

    A linear theory of the convergent instability (CI) of ionospheric plasma associated with the nonuniform nature of its regular motion is examined. The conditions under which CI appears in the E- and F-layers for vertical ion motion caused by various physical factors are analyzed. The possibility of small-scale strongly geomagnetic-field-aligned nonuniformities of electron concentration (l{sub min} {approximately} 10-30 m) is demonstrated. The altitude dependence of collision frequency is shown to play a large role in CI.

  6. Saturn: atmosphere, ionosphere, and magnetosphere.

    PubMed

    Gombosi, Tamas I; Ingersoll, Andrew P

    2010-03-19

    The Cassini spacecraft has been in orbit around Saturn since 30 June 2004, yielding a wealth of data about the Saturn system. This review focuses on the atmosphere and magnetosphere and briefly outlines the state of our knowledge after the Cassini prime mission. The mission has addressed a host of fundamental questions: What processes control the physics, chemistry, and dynamics of the atmosphere? Where does the magnetospheric plasma come from? What are the physical processes coupling the ionosphere and magnetosphere? And, what are the rotation rates of Saturn's atmosphere and magnetosphere?

  7. Saturn: atmosphere, ionosphere, and magnetosphere.

    PubMed

    Gombosi, Tamas I; Ingersoll, Andrew P

    2010-03-19

    The Cassini spacecraft has been in orbit around Saturn since 30 June 2004, yielding a wealth of data about the Saturn system. This review focuses on the atmosphere and magnetosphere and briefly outlines the state of our knowledge after the Cassini prime mission. The mission has addressed a host of fundamental questions: What processes control the physics, chemistry, and dynamics of the atmosphere? Where does the magnetospheric plasma come from? What are the physical processes coupling the ionosphere and magnetosphere? And, what are the rotation rates of Saturn's atmosphere and magnetosphere? PMID:20299587

  8. Waves in Space Plasmas Program

    NASA Technical Reports Server (NTRS)

    Fredricks, R. W.; Taylor, W. W. L.

    1981-01-01

    The Waves in Space Plasmas (WISP) program is a joint international effort involving instrumentation to be designed and fabricated by funding from NASA and the National Research Council of Canada. The instrumentation, with a tentatively planned payload for 1986, can be used to perturb the plasma with radio waves to solve problems in ionospheric, atmospheric, magnetospheric, and plasma physics. Among the ionospheric and plasma phenomena to be investigated using WISP instrumentation are VLF wave-particle interactions; ELF/VLF propagation; traveling ionospheric disturbances and gravity wave coupling; equatorial plasma bubble phenomena; plasma wave physics such as mode-coupling, dispersion, and instabilities; and plasma physics of the antenna-plasma interactions.

  9. Stationary electrostatic solitary waves in the auroral plasma

    NASA Technical Reports Server (NTRS)

    Lotko, W.; Kennel, C. F.

    1981-01-01

    Time-stationary fluid equations are used to describe electrostatic solitons in an auroral plasma of cold ionospheric and hot plasma sheet particles. A one-dimensional fluid analysis of the four component model auroral plasma indicates that at least two different, weakly damped, small amplitude electrostatic solitons can propagate along the geomagnetic field. The slower of the two is a generalization of an ion-acoustic solitary wave in a multi-component plasma, and ion inertia is negligible for the faster mode which is supported by the two electron components and resembles a clump of shielded negative space charge convected by the drifting plasma sheet electrons. Some expected features of the large amplitude properties are indicated qualitatively, and an analogy is considered between the theory of ion-acoustic shocks and a theory of double layers.

  10. Nonstationary coupling between the magnetosphere and ionosphere

    NASA Technical Reports Server (NTRS)

    Goertz, C. K.

    1983-01-01

    Resonant coupling of large scale MHD waves to small scale kinetic Alfven waves is described. The small-scale waves drive field-aligned currents tens of micro A/sqm into the ionosphere with accelerated electrons of energies a few keV. Bounce resonant interaction with standing kinetic Alfven waves may precipitate higher energy electrons. East-west aligned arcs should be thinnest and move polewards relative to the plasma at the poleward edge. Downward travelling wave packets trap electrons between the wave front and the ionosphere whose energy is below the peak energy and whose phase-space density should be independent of the peak energy.

  11. Modeling ionospheric electron precipitation due to wave particle scattering in the magnetosphere and the feedback effect on the magnetospheric dynamics

    NASA Astrophysics Data System (ADS)

    Yu, Y.; Jordanova, V.; Ridley, A. J.; Albert, J.; Horne, R. B.; Jeffery, C. A.

    2015-12-01

    Electron precipitation down to the atmosphere caused by wave-particle scattering in the magnetosphere contribute significantly to the enhancement of auroral ionospheric conductivity. Global MHD models that are incapable of capturing kinetic physics in the inner magnetosphere usually adopt MHD parameters to specify the precipitation flux to estimate auroral conductivity, hence losing self-consistency in the global circulation of the magnetosphere-ionosphere system. In this study we improve the coupling structure in global models by connecting the physics-based (wave-particle scattering) electron precipitation with the ionospheric electrodynamics and investigate the feedback effect on the magnetospheric dynamics. We use BATS-R-US coupled with a kinetic ring current model RAM-SCB that solves pitch angle dependent particle distributions to study the global circulation dynamics during the Jan 25-26, 2013 storm event. Following tail injections, we found enhanced precipitation number and energy fluxes of tens of keV electrons being scattered into loss cone due to interactions with enhanced chorus and hiss waves in the magnetosphere. This results in a more profound auroral conductance and larger electric field imposing on the plasma transport in the magnetosphere. We also compared our results with previous methods in specifying the auroral conductance, such as empirical relation used in Ridley et al. (2004). It is found that our physics-based method develops a larger convection electric field in the near-Earth region and therefore leads to a more intense ring current.

  12. Uplift of Ionospheric Oxygen Ions During Extreme Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Mannucci, Anthony J.; Verkhoglyadova, Olga P.; Huba, Joseph; Lakhina, Gurbax S.

    2013-01-01

    Research reported earlier in literature was conducted relating to estimation of the ionospheric electrical field, which may have occurred during the September 1859 Carrington geomagnetic storm event, with regard to modern-day consequences. In this research, the NRL SAMI2 ionospheric code has been modified and applied the estimated electric field to the dayside ionosphere. The modeling was done at 15-minute time increments to track the general ionospheric changes. Although it has been known that magnetospheric electric fields get down into the ionosphere, it has been only in the last ten years that scientists have discovered that intense magnetic storm electric fields do also. On the dayside, these dawn-to-dusk directed electric fields lift the plasma (electrons and ions) up to higher altitudes and latitudes. As plasma is removed from lower altitudes, solar UV creates new plasma, so the total plasma in the ionosphere is increased several-fold. Thus, this complex process creates super-dense plasmas at high altitudes (from 700 to 1,000 km and higher).

  13. Modeling the connection of the global ionospheric electric fields to the solar wind

    NASA Astrophysics Data System (ADS)

    Rothwell, P. L.; Jasperse, J. R.

    2006-03-01

    A global ionospheric electrostatic potential model, which we refer to as Nopper-Carovillano (N-C), can be linked with a magnetospheric potential model. The latter model, which we refer to as Hill-Siscoe-Ober (H-S-O), computes a transpolar potential ΦPC(H-S-O) based on solar wind parameters and region-1 field-aligned currents (FAC) from the magnetosheath to the ionosphere. The polar ionospheric conductance required by H-S-O is defined by the N-C model. In this way, the transpolar potential and the associated FAC are the same in both models. A distribution of region-1 FAC in the N-C model predicts a two-cell convection pattern which is in reasonable agreement with plasma drifts measured by DMSP (Defense Meteorological Satellite Program) satellites. The H-S-O model, as modified by N-C, is compared with the Weimer potential model and with the transpolar potentials observed by DMSP satellites during the 6-7 April 2000 magnetic storm. Good agreement is found in both cases. The region-2 (J2) current is estimated from the Siscoe (S-RC) ring-current circuit model which is driven by ΦPC(H-S-O). The resistor values in S-RC, as determined by N-C, when combined with the global potential solution, make it possible to estimate the time profile of the equatorial penetration electric field during the storm's main phase. With the values obtained, shielding occurs within 1 hour of onset. Equatorial plasma bubbles (EPBs) are seen some hours after the initial increase of ΦPC and are qualitatively consistent with the equatorial penetration electric field calculated by the combined model.

  14. Formation of Polar Ionospheric Tongue of Ionization during Minor Geomagnetic Disturbed Conditions

    NASA Astrophysics Data System (ADS)

    Liu, J.; Wang, W.; Burns, A. G.; Yue, X.; Zhang, S.; Zhang, Y.

    2015-12-01

    Previous investigations of ionospheric storm-enhanced density (SED) and tongue of ionization (TOI) focused mostly on the behavior of TOI during intense geomagnetic storms. Little attention has been paid to the spatial and temporal variations of TOI during weak to moderate geomagnetic disturbed conditions. we investigate the source and development of TOI during a moderate geomagnetic storm on 14 October 2012.Multi-instrumental observations including GPS total electron content (TEC), Defense Meteorological SatelliteProgram(DMSP) in situ measured total ion concentration and ion drift velocity, SuperDARN measured polar ionconvection patterns, and electron density profiles from the Poker Flat Incoherent Scatter Radar (PFISR) have been utilized in the current analysis. GPS TEC maps show salient TOI structures persisting for about 5 h over high latitudes of North America on 14 October 2012 in the later recovery phase of the storm when the magnitudes of IMF By and Bz were less than 5 nT. The PFISR electron density profiles indicate that the extra ionization for TEC enhancements mainly occurred in the topside ionosphere with no obvious changes in the bottom side ionosphere and vertical plasma drifts. Additionally, there were no signatures of penetration electric fields in the equatorial electrojet data and upward ion drifts at high latitudes. At the same time, strong subauroral polarization streams with ion drift speeds exceeding 2.5 km/s carried sunward fluxes and migrated toward lower latitudes for about 5° based on the DMSP cross-track driftmeasurements. Based on those measurements,we postulate that the combined effects of initial build-up of ionization at midlatitudes through daytime production of ionization and equatorward (or less poleward than normal daytime) neutral wind reducing downward diffusion along the inclined filed lines, and an expanded polar ion convection pattern and its associated horizontal plasma transport are important in the formation of the TOI.

  15. Positive and negative ionospheric storms occurring during the 15 May 2005 geomagnetic superstorm

    NASA Astrophysics Data System (ADS)

    Horvath, Ildiko; Lovell, Brian C.

    2015-09-01

    This study focuses on the 15 May 2005 geomagnetic superstorm and aims to investigate the global variation of positive and negative storm phases and their development. Observations are provided by a series of global total electron content maps and multi-instrument line plots. Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe) simulations are also employed. Results reveal some sunward streaming plumes of storm-enhanced density (SED) over Asia and a well-developed midlatitude trough over North America forming isolated positive and negative storms, respectively. The simultaneous development of positive and negative storms over North America is also shown. Then, some enhanced auroral ionizations maintained by strong equatorward neutral winds appeared in the depleted nighttime ionosphere. Meanwhile, the northern nighttime polar region became significantly depleted as the SED plume plasma could not progress further than the dayside cusp. Oppositely, a polar tongue of ionization (TOI) developed in the daytime southern polar region. According to CTIP simulations, solar heating locally maximized (minimized) over the southern (northern) magnetic pole. Furthermore, strong upward surges of molecular-rich air created O/N2 decreases both in the auroral zone and in the trough region, while some SED-related downward surges produced O/N2 increases. From these results we conclude for the time period studied that (1) composition changes contributed to the formation of positive and negative storms, (2) strengthening polar convection and increasing solar heating of the polar cap supported polar TOI development, and (3) a weaker polar convection and minimized solar heating of the polar cap aided the depletion of polar plasma.

  16. Effects of magnetospheric lobe cell convection on dayside upper thermospheric winds at high latitudes

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Wang, W.; Wu, Q.; Knipp, D.; Kilcommons, L.; Brambles, O. J.; Liu, J.; Wiltberger, M.; Lyon, J. G.; Häggström, I.

    2016-08-01

    This paper investigates a possible physical mechanism of the observed dayside high-latitude upper thermospheric wind using numerical simulations from the coupled magnetosphere-ionosphere-thermosphere (CMIT) model. Results show that the CMIT model is capable of reproducing the unexpected afternoon equatorward winds in the upper thermosphere observed by the High altitude Interferometer WIND observation (HIWIND) balloon. Models that lack adequate coupling produce poleward winds. The modeling study suggests that ion drag driven by magnetospheric lobe cell convection is another possible mechanism for turning the climatologically expected dayside poleward winds to the observed equatorward direction. The simulation results are validated by HIWIND, European Incoherent Scatter, and Defense Meteorological Satellite Program. The results suggest a strong momentum coupling between high-latitude ionospheric plasma circulation and thermospheric neutral winds in the summer hemisphere during positive IMF Bz periods, through the formation of magnetospheric lobe cell convection driven by persistent positive IMF By. The CMIT simulation adds important insight into the role of dayside coupling during intervals of otherwise quiet geomagnetic activity

  17. International reference ionosphere 1990

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter; Rawer, K.; Bossy, L.; Kutiev, I.; Oyama, K.-I.; Leitinger, R.; Kazimirovsky, E.

    1990-01-01

    The International Reference Ionosphere 1990 (IRI-90) is described. IRI described monthly averages of the electron density, electron temperature, ion temperature, and ion composition in the altitude range from 50 to 1000 km for magnetically quiet conditions in the non-auroral ionosphere. The most important improvements and new developments are summarized.

  18. Solar wind interaction with the ionosphere of Venus inferred from radio scintillation measurements

    SciTech Connect

    Woo, R.; Sjogren, W.L.; Kliore, A.J. ); Luhmann, J.G. ); Brace, L.H. )

    1989-02-01

    This paper presents the first S-band (2.3 GHz) radio scintillations observed in the ionosphere of Venus and discovered when the Pioneer Venus Orbiter spacecraft traversed the ionosphere of Venus. In situ plasma measurements as well as propagation calculations confirm that the scintillations are caused by electron density irregularities in the topside ionosphere of Venus below the ionopause. While these topside plasma irregularities have not been studied before, simultaneous magnetic field measurements presented here reveal that they are associated with the penetration of large-scale magnetic fields in the ionosphere. Previous studies based on extensive magnetic field measurements have shown that the presence of large-scale magnetic fields occurs in the subsolar region when the solar wind dynamic pressure exceeds the ionospheric plasma pressure. As with the large-scale magnetic fields, the disturbed plasma and resulting scintillations are therefore a manifestation of high-dynamic solar wind interaction with the ionosphere. Since the scintillations only occur in the subsolar region of Venus, the global morphology of ionospheric scintillations at Venus is different from that of the terrestrial ionosphere, where scintillations are observed in both polar and equatorial regions, with peaks occurring during nighttime. This difference apparently stems from the fact that Venus is not a magnetic planet. The authors also demonstrate that the disturbed plasma produced by the high-dynamic solar wind interaction can be remotely sensed by scintillations during radio occultation measurements, that is, when the spacecraft is outside the ionosphere.

  19. A numerical simulation of the geomagnetic sudden commencement: 2. Plasma processes in the main impulse

    NASA Astrophysics Data System (ADS)

    Fujita, S.; Tanaka, T.; Kikuchi, T.; Fujimoto, K.; Itonaga, M.

    2003-12-01

    A geomagnetic sudden commencement (SC) is studied numerically based on a model of buffeting the magnetosphere by a solar wind density impulse. This paper treats two successive current systems in the main impulse (MI) phase. The two current systems have different current generating mechanisms. The first current generator appears behind the wavefront of a compressional disturbance launched by the impulse. The inertia current of the compressional mode is generated by free energy due to deceleration of plasma flows. A field-aligned current (FAC) is excited through mode conversion from the compressional wave in a VA gradient region. The magnetospheric flows and the ionospheric flows are not connected self-consistently to each other. The second generator is located in the tailward side of the cusp. It is the same as the generator of the region 1 current system. The current generated there is connected with the FAC with the region 1 sense via a diamagnetic current flowing around an isolated enhancement of pressure in the nightside equatorial magnetosphere. The pressure enhancement is induced through compression of the magnetospheric flank due to the solar wind impulse. In this period, plasma convection vortices appear both in the magnetosphere and in the ionosphere, which are correspondent to each other. This is a peculiar convection confined within the magnetosphere (the SC transient cell convection). This convection is driven though compression of the magnetospheric flank due to the solar wind impulse.

  20. Simulations of Steady Magnetospheric Convection

    NASA Astrophysics Data System (ADS)

    Lemon, C.; Toffoletto, F.; Sazykin, S.; Wolf, R.

    2003-12-01

    Steady Magnetospheric Convection in the Earth's magnetosphere is typically defined as a period of several hours of enhanced solar wind driving of the magnetosphere (i.e. the Interplanetary Magnetic Field is southward) during which the magnetosphere is nonetheless devoid of substorm signatures. We present and discuss model results of generic Steady Magnetospheric Convection (SMC) events using the Self-consistent Rice Convection Model. The SRCM consists of two coupled models that are used to separately compute the plasma and magnetic field evolution. The Rice Convection Model (RCM) is a multi-fluid guiding-center plasma drift code used to simulate plasma dynamics under the assumption that convection can be modeled quasi-statically as a sequence of force-balanced states. The RCM has been coupled to an equilibrium solver that computes a magnetic field that is in force-balance (and is therefore self-consistent) with the RCM's plasma distribution. Various levels of steady external driving conditions are imposed in order to contrast the ability of the model magnetosphere to respond to differing rates of energy input and form a steady-state convection pattern. Model results will be compared with empirical SMC morphology.

  1. The role of the zonal E×B plasma drift in the low-latitude ionosphere at high solar activity near equinox from a new three-dimensional theoretical model

    NASA Astrophysics Data System (ADS)

    Pavlov, A. V.

    2006-10-01

    A new three-dimensional, time-dependent theoretical model of the Earth's low and middle latitude ionosphere and plasmasphere has been developed, to take into account the effects of the zonal E×B plasma drift on the electron and ion number densities and temperatures, where E and B are the electric and geomagnetic fields, respectively. The model calculates the number densities of O+(4S), H+, NO+, O2+, N2+, O+(2D), O+(2P), O+(4P), and O+(2P*) ions, the electron density, the electron and ion temperatures using a combination of the Eulerian and Lagrangian approaches and an eccentric tilted dipole approximation for the geomagnetic field. The F2-layer peak density, NmF2, and peak altitude, hmF2, which were observed by 16 ionospheric sounders during the 12-13 April 1958 geomagnetically quiet time high solar activity period are compared with those from the model simulation. The reasonable agreement between the measured and modeled NmF2 and hmF2 requires the modified equatorial meridional E×B plasma drift given by the Scherliess and Fejer (1999) model and the modified NRLMSISE-00 atomic oxygen density. In agreement with the generally accepted assumption, the changes in NmF2 due to the zonal E×B plasma drift are found to be inessential by day, and the influence of the zonal E×B plasma drift on NmF2 and hmF2 is found to be negligible above about 25° and below about -26° geomagnetic latitude, by day and by night. Contrary to common belief, it is shown, for the first time, that the model, which does not take into account the zonal E×B plasma drift, underestimates night-time NmF2 up to the maximum factor of 2.3 at low geomagnetic latitudes, and this plasma transport in geomagnetic longitude is found to be important in the calculations of NmF2 and hmF2 by night from about -20° to about 20° geomagnetic latitude. The longitude dependence of the night-time low-latitude influence of the zonal E×B plasma drift on NmF2, which is found for the first time, is explained in terms

  2. Ionospheric effects during severe space weather events seen in ionospheric service data products

    NASA Astrophysics Data System (ADS)

    Jakowski, Norbert; Danielides, Michael; Mayer, Christoph; Borries, Claudia

    Space weather effects are closely related to complex perturbation processes in the magnetosphere-ionosphere-thermosphere systems, initiated by enhanced solar energy input. To understand and model complex space weather processes, different views on the same subject are helpful. One of the ionosphere key parameters is the Total Electron Content (TEC) which provides a first or-der approximation of the ionospheric range error in Global Navigation Satellite System (GNSS) applications. Additionally, horizontal gradients and time rate of change of TEC are important for estimating the perturbation degree of the ionosphere. TEC maps can effectively be gener-ated using ground based GNSS measurements from global receiver networks. Whereas ground based GNSS measurements provide good horizontal resolution, space based radio occultation measurements can complete the view by providing information on the vertical plasma density distribution. The combination of ground based TEC and vertical sounding measurements pro-vide essential information on the shape of the vertical electron density profile by computing the equivalent slab thickness at the ionosonde station site. Since radio beacon measurements at 150/400 MHz are well suited to trace the horizontal structure of Travelling Ionospheric Dis-turbances (TIDs), these data products essentially complete GNSS based TEC mapping results. Radio scintillation data products, characterising small scale irregularities in the ionosphere, are useful to estimate the continuity and availability of transionospheric radio signals. The different data products are addressed while discussing severe space weather events in the ionosphere e.g. events in October/November 2003. The complementary view of different near real time service data products is helpful to better understand the complex dynamics of ionospheric perturbation processes and to forecast the development of parameters customers are interested in.

  3. Highly Structured Plasma Density and Associated Electric and Magnetic Field Irregularities at Sub-Auroral, Middle, and Low Latitudes in the Topside Ionosphere Observed with the DEMETER and DMSP Satellites

    NASA Technical Reports Server (NTRS)

    Pfaff, Robert F.; Liebrecht, C; Berthelier, Jean-Jacques; Parrot, M.; Lebreton, Jean-Pierre

    2007-01-01

    Detailed observations of the plasma structure and irregularities that characterize the topside ionosphere at sub-auroral, middle, and low-latitudes are gathered with probes on the DEMETER and DMSP satellites. In particular, we present DEMETER observations near 700 km altitude that reveal: (1) the electric field irregularities and density depletions at mid-latitudes are remarkably similar to those associated with equatorial spread-F at low latitudes; (2) the mid-latitude density structures contain both depletions and enhancements with scale lengths along the spacecraft trajectory that typically vary from 10's to 100's of km; (3) in some cases, ELF magnetic field irregularities are observed in association with the electric field irregularities on the walls of the plasma density structures and appear to be related to finely-structured spatial currents and/or Alfven waves; (4) during severe geomagnetic storms, broad regions of nightside plasma density structures are typically present, in some instances extending from the equator to the subauroral regions; and (5) intense, broadband electric and magnetic field irregularities are observed at sub-auroral latitudes during geomagnetic storm periods that are typically associated with the trough region. Data from successive DEMETER orbits during storm periods in both the daytime and nighttime illustrate how enhancements of both the ambient plasma density, as well as sub-auroral and mid-latitude density structures, correlate and evolve with changes in the Dst. The DEMETER data are compared with near simultaneous observations gathered by the DMSP satellites near 840 km. The observations are related to theories of sub-auroral and mid-latitude plasma density structuring during geomagnetic storms and penetration electric fields and are highly germane to understanding space weather effects regarding disruption of communication and navigation signals in the near-space environment.

  4. Inertial currents in isotropic plasma

    NASA Technical Reports Server (NTRS)

    Heinemann, M.; Erickson, G. M.; Pontius, D. H., Jr.

    1994-01-01

    The magnetospheric convection electric field contributes to Birkeland currents. The effects of the field are to polarize the plasma by displacing the bounce paths of the ions from those of electrons, to redistribute the pressure so that it is not constant along magnetic field lines, and to enhance the pressure gradient by the gradient of the bulk speed. Changes in the polarization charge during the convection of the plasma are neutralized by electrons in the form of field-aligned currents that close through the ionosphere. The pressure drives field-aligned currents through its gradient in the same manner as in quasi-static plasmas, but with modifications that are important if the bulk speed is of the order of the ion thermal speed; the variations in the pressure along field lines are maintained by a weak parallel potential drop. These effects are described in terms of the field-aligned currents in steady state, isotropic, MHD plasma. Solutions are developed by taking the MHD limit ot two-fluid solutions and illustrated in the special case of Maxwellian plasma for which the temperature is constant along magnetic field lines. The expression for the Birkeland current density is a generalization of Vasyliunas' expression for the field-aligned current density in quasi-static plasma and provides a unifying expression when both pressure gradients and ion inertia operate simultaneously as sources of field-aligned currents. It contains a full account of different aspects of the ion flow (parallel and perpendicular velocity and vorticity) that contribute to the currents. Contributions of ion inertia to field-aligned currents will occur in regions of strong velocity shear, electric field reversal, or large gradients in the parallel velocity or number density, and may be important in the low-latitude boundary layer, plasma sheet boundary layer, and the inner edge region of the plasma sheet.

  5. Reflected solar wind ions and downward accelerated ionospheric ions during the January 1997 magnetic cloud event

    NASA Astrophysics Data System (ADS)

    Dempsey, D. L.; Burch, J. L.; Huddleston, M. M.; Pollock, C. J.; Waite, J. H., Jr.; Wüest, M.; Moore, T. E.; Shelley, E. G.

    On January 11, 1997, at 03:40:00 UT, while Polar was traveling up the dusk flank toward apogee, two ion instruments, TIDE and TIMAS, detected upflowing H+ with an energy/pitch-angle dispersion resembling an ionospheric reflection of freshly injected solar wind ions. In the same region of space, TIDE and TIMAS observed cold beams of O+ and H+ traveling down the field line with equal bulk velocities. We interpret these ion signatures as concurrent observations of mirrored solar wind ions and downward accelerated ionospheric ions. By 03:42:00, an energy/pitch-angle dispersion of downward moving ions at very low energies was clearly evident in the TIDE data. This additional signature is interpreted as an indication of reconnection on the same field line in the southern hemisphere. We explain this unique combination of plasma distributions in terms of high-latitude reconnection and magnetic field line convection during northward-IMF conditions associated with the January 1997 magnetic cloud event.

  6. Ionospheric response to the High Speed Solar Streams during last solar minimum

    NASA Astrophysics Data System (ADS)

    Mosna, Zbysek; Koucka Knizova, Petra; Georgieva, Katya

    Ionosphere is a highly variable system. Response of ionospheric plasma to the High Speed Solar Streams (HSS) by means of critical frequencies fof2, heights of maximum electron concentration hmf2 and the occurrence of sporadic E-layer during last prolonged solar minimum is presented and we compare it to previous studies. State of the ionosphere depends on the daytime, season, phase of solar cycle etc. The extent of ionospheric response to the solar event (HSS, CME etc.) is a subject of mentioned conditions and strength of solar event itself but it also significantly depends on the actual geomagnetic and ionospheric situation and the memory of the system, e.g. length of the preceding quiet or disturbed period. Ionospheric storms have been relatively widely studied. However, last solar minimum gives us an exceptional possibility to study ionospheric processes under conditions of unusually long time of low solar activity.

  7. Mesoscale ionospheric tomography at the Auroral region

    NASA Astrophysics Data System (ADS)

    Luntama, J.; Kokkatil, G. V.

    2008-12-01

    FMI (Finnish Meteorological Institute) has used observations from the dense GNSS network in Finland for high resolution regional ionospheric tomography. The observation system used in this work is the VRS (Virtual Reference Station) network in Finland operated by Geotrim Ltd. This network contains 86 GNSS ground stations providing two frequency GPS and GLONASS observations with the sampling rate of 1 Hz. The network covers the whole Finland and the sampling of the ionosphere is very good for observing mesoscale ionospheric structures at the Auroral region. The ionospheric tomography software used by FMI is the MIDAS (Multi-Instrument Data Analysis System) algorithm developed and implemented by the University of Bath (Mitchell and Spencer, 2003). MIDAS is a 3-D extension of the 2-D tomography algorithm originally presented by Fremouw et al. (1992). The research at FMI is based on ground based GNSS data collected in December 2006. The impacts of the two geomagnetic storms during the month are clearly visible in the retrieved electron density and TEC maps and they can be correlated with the magnetic field disturbances measured by the IMAGE magnetometer network. This is the first time that mesoscale structures in the ionospheric plasma can be detected from ground based GNSS observations at the Auroral region. The continuous high rate observation data from the Geotrim network allows monitoring of the temporal evolution of these structures throughout the storms. Validation of the high resolution electron density and TEC maps is a challenge as independent reference observations with a similar resolution are not available. FMI has compared the 3-D electron density maps against the 2-D electron density plots retrieved from the observations from the Ionospheric Tomography Chain operated by the Sodankylä Geophysical Observatory (SGO). Additional validation has been performed with intercomparisons with observations from the ground based magnetometer and auroral camera network

  8. Ionospheric storms on Mars: Impact of the corotating interaction region

    NASA Astrophysics Data System (ADS)

    Dubinin, E.; Fraenz, M.; Woch, J.; Duru, F.; Gurnett, D.; Modolo, R.; Barabash, S.; Lundin, R.

    2009-01-01

    Measurements made by the ASPERA-3 and MARSIS experiments on Mars Express have shown, for the first time, that space weather effects related to the impact of a dense and high pressure solar wind (corotating interaction region) on Mars cause strong perturbations in the martian induced magnetosphere and ionosphere. The magnetic barrier formed by pile-up of the draped interplanetary magnetic field ceases to be a shield for the incoming solar wind. Large blobs of solar wind plasma penetrate to the magnetosphere and sweep out dense plasma from the ionosphere. The topside martian ionosphere becomes very fragmented consisting of intermittent cold/low energy and energized plasmas. The scavenging effect caused by the intrusions of solar wind plasma clouds enhances significantly (by a factor of >=10) the losses of volatile material from Mars.

  9. Supergranular Convection

    NASA Astrophysics Data System (ADS)

    Udayashankar, Paniveni

    2015-12-01

    Observation of the Solar photosphere through high resolution instruments have long indicated that the surface of the Sun is not a tranquil, featureless surface but is beset with a granular appearance. These cellular velocity patterns are a visible manifestation of sub- photospheric convection currents which contribute substantially to the outward transport of energy from the deeper layers, thus maintaining the energy balance of the Sun as a whole.Convection is the chief mode of transport in the outer layers of all cool stars such as the Sun (Noyes,1982). Convection zone of thickness 30% of the Solar radius lies in the sub-photospheric layers of the Sun. Here the opacity is so large that heat flux transport is mainly by convection rather than by photon diffusion. Convection is revealed on four scales. On the scale of 1000 km, it is granulation and on the scale of 8-10 arcsec, it is Mesogranulation. The next hierarchial scale of convection , Supergranules are in the range of 30-40 arcsec. The largest reported manifestation of convection in the Sun are ‘Giant Cells’or ‘Giant Granules’, on a typical length scale of about 108 m.'Supergranules' is caused by the turbulence that extends deep into the convection zone. They have a typical lifetime of about 20hr with spicules marking their boundaries. Gas rises in the centre of the supergranules and then spreads out towards the boundary and descends.Broadly speaking supergranules are characterized by the three parameters namely the length L, the lifetime T and the horizontal flow velocity vh . The interrelationships amongst these parameters can shed light on the underlying convective processes and are in agreement with the Kolmogorov theory of turbulence as applied to large scale solar convection (Krishan et al .2002 ; Paniveni et. al. 2004, 2005, 2010).References:1) Noyes, R.W., The Sun, Our Star (Harvard University Press, 1982)2) Krishan, V., Paniveni U., Singh , J., Srikanth R., 2002, MNRAS, 334/1,2303) Paniveni

  10. Ionospheric and tropospheric scintillation as a form of noise

    NASA Technical Reports Server (NTRS)

    Fremouw, E. J.; Rino, C. L.

    1975-01-01

    Recent tests of signals observed through the ionosphere, the solar wind, and a laboratory plasma have revealed a surprising consistency in parameters describing the first order statistics of a signal caused to scintillate by a randomly structured plasma. This paper describes a means for exploiting these new findings in a transionospheric communication channel model.

  11. Modeling Ionospheric Electrodynamics (Invited)

    NASA Astrophysics Data System (ADS)

    Huba, J. D.

    2009-12-01

    We present modeling results of ionospheric electrodynamics using the 3D NRL ionosphere model SAMI3. Recently, SAMI3 has been upgraded to solve the potential equation that determines the electrostatic potential from the ionospheric conductances (Pedersen and Hall) and drivers: neutral wind, gravity, and parallel current systems. We present results showing the impact of different neutral wind models (e.g., HWM93, HWM07, TIMEGCM) on the dynamics of the low- to mid-latitude ionosphere, as well as the Region 1 and 2 current systems. We point out issues and concerns with obtaining an accurate specification of the global electric field within the context of existing models.(with J. Krall, G. Joyce, S. Slinker, and G. Crowley). Research supported by NASA and ONR

  12. Experimental evidence of electromagnetic pollution of ionosphere

    NASA Astrophysics Data System (ADS)

    Pronenko, Vira; Korepanov, Valery; Dudkin, Denis

    The Earth’s ionosphere responds to external perturbations originated mainly in the Sun, which is the primary driver of the space weather (SW). But solar activity influences on the ionosphere and the Earth's atmosphere (i.e., the energy transfer in the direction of the Sun-magnetosphere-ionosphere-atmosphere-surface of the Earth), though important, is not a unique factor affecting its state - there is also a significant impact of the powerful natural and anthropogenic processes, which occur on the Earth’s surface and propagating in opposite direction along the Earth’s surface-atmosphere-ionosphere-magnetosphere chain. Numerous experimental data confirm that the powerful sources and consumers of electrical energy (radio transmitters, power plants, power lines and industrial objects) cause different ionospheric phenomena, for example, changes of the electromagnetic (EM) field and plasma in the ionosphere, and affect on the state of the Earth atmosphere. Anthropogenic EM effects in the ionosphere are already observed by the scientific satellites and the consequences of their impact on the ionosphere are not currently known. Therefore, it is very important and urgent task to conduct the statistically significant research of the ionospheric parameters variations due to the influence of the powerful man-made factors, primarily owing to substantial increase of the EM energy production. Naturally, the satellite monitoring of the ionosphere and magnetosphere in the frequency range from tens of hertz to tens of MHz with wide ground support offers the best opportunity to observe the EM energy release, both in the global and local scales. Parasitic EM radiation from the power supply lines, when entering the ionosphere-magnetosphere system, might have an impact on the electron population in the radiation belt. Its interaction with trapped particles will change their energy and pitch angles; as a result particle precipitations might occur. Observations of EM emission by

  13. Topside ionospheric response to solar EUV variability

    NASA Astrophysics Data System (ADS)

    Anderson, Phillip C.; Hawkins, Jessica M.

    2016-02-01

    We present an analysis of 23 years of thermal plasma measurements in the topside ionosphere from the Defense Meteorological Satellite Program (DMSP) spacecraft. The H+/O+ ratio and density vary dramatically with the solar cycle; cross-correlation coefficients between E10.7 and the daily averaged densities are greater than 0.85. The ionospheric parameters also vary dramatically with season, particularly at latitudes away from the equator where the solar zenith angle varies greatly with season. There are also 27 day solar rotation periodicities in the density, associated with periodicities in the directly measured solar EUV flux. Empirical orthogonal function analysis captures over 95% of the variation in the density in the first two principal components. The first principal component (PC1) is clearly associated with the solar EUV while the second principal component (PC2) is clearly associated with the solar zenith angle variation. The magnitude of the variation of the response of the topside ionosphere to solar EUV variability is shown to be closely related to the ionospheric composition. This is interpreted as the result of the effect of composition on the scale height in the topside ionosphere and the "pivot effect" in which the variation in density near the F2 peak is amplified by a factor of e at an altitude a scale height above the F2 peak. When the topside ionosphere is H+ dominated during solar minimum, DMSP may be much less than a scale height above the F2 peak while during solar maximum, when it is O+ dominated, DMSP may be several scale heights above the F2 peak.

  14. Martian ionosphere response to solar wind variability during solar minimum

    NASA Astrophysics Data System (ADS)

    Sanchez-Cano, Beatriz; Lester, Mark; Witasse, Olivier; Mays, M. Leila; Hall, Benjamin E. S.; Milan, Stephen E.; Cartacci, Marco; Blelly, Pierre-Louis; Andrews, David; Opgenoorth, Hermann; Odstrcil, Dusan

    2016-04-01

    Solar cycle variations in solar radiation create notable density changes in the Martian ionosphere. In addition to this long-term variability, there are numerous short-term and non-recurrent solar events that hit Mars which need to be considered, such as Interplanetary Coronal Mass Ejections (ICMEs), Co-Rotation Interaction Regions (CIRs), solar flares, or solar wind high speed streams. The response of the Martian plasma system to each of these events is often unusual, especially during the long period of extreme low solar activity in 2008 and 2009. This work shows the long-term solar cycle impact on the ionosphere of Mars using data from The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), and The Analyzer of Space Plasma and Energetic Atoms (ASPERA-3), and with empirical and numerical models on Mars Express. Particular attention is given to the different ionospheric responses observed during the last, extended solar minimum. Mars' ionospheric response followed a similar pattern to the response observed in the Earth's ionosphere, despite the large differences related to the inner-origin of the magnetic field of both planets. The ionospheric temperature was cooler, the topside scale height was smaller and almost constant with altitude, the secondary ionospheric layer practically disappeared and the whole atmospheric total electron content (TEC) suffered an extreme reduction of about 30-40%, not predicted before by models. Moreover, there is a larger probability for the induced magnetic field to be present in the ionosphere, than in other phases of the solar cycle. The short-term variability is also addressed with the study of an ICME followed by a fast stream that hit Mars in March 2008, where solar wind data are provided by ACE and STEREO-B and supported by simulations using the WSA-ENLIL Model. The solar wind conditions lead to the formation of a CIR centred on the interface of the fast and the slow solar wind streams. Mars' system reacted to

  15. Dayside Ionospheric Superfountain

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Verkhoglyadova, Olga P.; Mannucci, Anthony J.

    2010-01-01

    The Dayside Ionospheric Super-fountain modified SAMI2 code predicts the uplift, given storm-time electric fields, of the dayside near-equatorial ionosphere to heights of over 800 kilometers during magnetic storm intervals. This software is a simple 2D code developed over many years at the Naval Research Laboratory, and has importance relating to accuracy of GPS positioning, and for satellite drag.

  16. The Flow of Plasma in the Solar-Terrestrial Environment

    NASA Technical Reports Server (NTRS)

    Schunk, Robert W.; Sojka, Jan J.; Barakat, Abdallah R.; Demars, Howard G.; Zhu, Lie

    2005-01-01

    The overall goal of our NASA theory research is to trace the flow of mass, momentum, and energy through the magnetosphere-ionosphere-atmosphere system taking into account the coupling, time delays, and feedback mechanisms that are characteristic of the system. Our approach is to model the magnetosphere-ionosphere-atmosphere (M-I-A) system in a self-consistent quantitative manner using unique global models that allow us to study the coupling between the different regions on a range of spatial and temporal scales. The uniqueness of our global models stems from their high spatial and temporal resolutions, the physical processes included, and the numerical techniques employed. Currently, we have time-dependent global models of the ionosphere, thermosphere, polar wind, plasmasphere, and electrodynamics. It is now becoming clear that a significant fraction of the flow of mass, momentum, and energy in the M-I-A system occurs on relatively small spatial scales. Therefore, an important aspect of our NASA Theory program concerns the effect that mesoscale (100-l000 km) density structures have on the macroscopic flows in the ionosphere, thermosphere, and polar wind. The structures can be created either by structured magnetospheric inputs (i.e., structured electric field, precipitation, or Birkeland current patterns) or by time variations of these inputs due to geomagnetic storms and substorms. Some of the mesoscale structures of interest include sun-aligned polar cap arcs, propagating plasma patches, traveling convection vortices, subauroral ion drift (SAID) channels, gravity waves, and the polar hole.

  17. Tsunami Ionospheric warning and Ionospheric seismology

    NASA Astrophysics Data System (ADS)

    Lognonne, Philippe; Rolland, Lucie; Rakoto, Virgile; Coisson, Pierdavide; Occhipinti, Giovanni; Larmat, Carene; Walwer, Damien; Astafyeva, Elvira; Hebert, Helene; Okal, Emile; Makela, Jonathan

    2014-05-01

    The last decade demonstrated that seismic waves and tsunamis are coupled to the ionosphere. Observations of Total Electron Content (TEC) and airglow perturbations of unique quality and amplitude were made during the Tohoku, 2011 giant Japan quake, and observations of much lower tsunamis down to a few cm in sea uplift are now routinely done, including for the Kuril 2006, Samoa 2009, Chili 2010, Haida Gwai 2012 tsunamis. This new branch of seismology is now mature enough to tackle the new challenge associated to the inversion of these data, with either the goal to provide from these data maps or profile of the earth surface vertical displacement (and therefore crucial information for tsunami warning system) or inversion, with ground and ionospheric data set, of the various parameters (atmospheric sound speed, viscosity, collision frequencies) controlling the coupling between the surface, lower atmosphere and the ionosphere. We first present the state of the art in the modeling of the tsunami-atmospheric coupling, including in terms of slight perturbation in the tsunami phase and group velocity and dependance of the coupling strength with local time, ocean depth and season. We then show the confrontation of modelled signals with observations. For tsunami, this is made with the different type of measurement having proven ionospheric tsunami detection over the last 5 years (ground and space GPS, Airglow), while we focus on GPS and GOCE observation for seismic waves. These observation systems allowed to track the propagation of the signal from the ground (with GPS and seismometers) to the neutral atmosphere (with infrasound sensors and GOCE drag measurement) to the ionosphere (with GPS TEC and airglow among other ionospheric sounding techniques). Modelling with different techniques (normal modes, spectral element methods, finite differences) are used and shown. While the fits of the waveform are generally very good, we analyse the differences and draw direction of future

  18. A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

    NASA Technical Reports Server (NTRS)

    Simoes, Fernando; Pfaff, Robert; Berthelier, Jean-Jacques; Klenzing, Jeffrey

    2012-01-01

    Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave propagation in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfven waves and particle precipitation related to solar and magnetospheric processes. We review in situ ionospheric processes as well as surface and space weather phenomena that drive troposphere-ionosphere dynamics. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. We also briefly revisit ionospheric irregularities such as spread-F and explosive spread-F, sporadic-E, traveling ionospheric disturbances, Trimpi effect, and hiss and plasma turbulence. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and solving inverse problems and summarize in a final section a few challenging subjects that are important for a better understanding of tropospheric-ionospheric coupling mechanisms.

  19. Storm-time Magnetospheric Effects on Electric Fields in the Subauroral Ionosphere

    NASA Astrophysics Data System (ADS)

    Wolf, R. A.; Garner, T. W.; Goldstein, J.; Sazykin, S.; Spiro, R. W.

    2001-12-01

    Although the inner edge of the plasma sheet tends to shield the mid- and low-latitude ionosphere from the full force of magnetospheric convection, the shielding is particularly ineffective during magnetic storms. This talk will review several effects that represent quick responses to magnetospheric drivers, specifically the following: 1. Overshielding and undershielding. The overshielding electric fields, which occur during convection decreases, were predicted theoretically and observed in the post-midnight sector more than twenty years ago. The predicted patterns have been largely confirmed by statistical analysis of radar observations, although it has been necessary to modify the original overshielding idea somewhat to be consistent with the observed strength and duration. Overshielding has also been seen in plasmaspheric observations, most recently by the IMAGE spacecraft. Simulations of the main phase of a large storm predict the sustained presence of an undershielding (direct penetration) eastward electric field in the post-dusk sector, possibly triggering scintillations there. 2. Polarization jets. Simulations indicate that strong ring current injection is accompanied by a several-degree-wide westward-moving jet of plasma in the dusk-midnight quadrant, just equatorward of the auroral zone. These have been observed in recent years from CRRES and Millstone Hill. 3. Interchange-associated electric-field eddies. These are predicted by recent Rice Convection Model simulations and have not, as far as we know, been reported observationally. We predict their occurrence in the early recovery phase of a magnetic storm whose main phase terminates with a strong and sustained northward turning of the interplanetary magnetic field. They should occur in a band roughly 5 degrees wide, just equatorward of the auroral zone, in the dusk-midnight sector.

  20. Low Altitude Initiation of Ionospheric Upflow and Outflow

    NASA Astrophysics Data System (ADS)

    Burleigh, M.; Zettergren, M. D.; Rowland, D. E.; Klenzing, J.

    2015-12-01

    Significant amounts of ionospheric plasma can be transported to high altitudes (above 1000 km) in response to a variety of plasma heating and uplifting processes. Soft electron precipitation heats ambient, F-region ionospheric electrons creating electron pressure increases and upflows. Strong DC electric fields frictionally heat the ion population also resulting in ion upflows. Lastly, field-aligned thermospheric winds can contribute to ion motion at lower altitudes, while geomagnetically perpendicular winds may affect frictional heating. Once ions have been lifted to high altitudes, transverse ion acceleration by broadband ELF waves can give the upflowing ions sufficient energy to escape into the magnetosphere (ionospheric outflow). This study examines the thermospheric wind regulation of ionospheric upflow and outflow with a focus on how lower ionosphere dynamics feed source populations for transverse energization and determine the types, and amounts, of outflowing ions. The model used here for this study is a 2D ionospheric model based on a modified 16-moment transport description. It solves conservation of mass, momentum, and parallel and perpendicular energy for all relevant ionospheric species. 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. This model is used to conduct a parametric study of neutral wind effects on upflow and outflow and highlights how low-altitude processes affect ion outflow through the regulation of source plasma available to higher altitudes. This model is also used to construct a case study of ion outflows at the nightside polar cap boundary using data from the VISIONS sounding rocket campaign.

  1. Scintillation Observations and Response of The Ionosphere to Electrodynamics (SORTIE)

    NASA Astrophysics Data System (ADS)

    Crowley, G.

    2015-12-01

    The Scintillation Observations and Response of The Ionosphere to Electrodynamics, or SORTIE, mission is a 6U NASA Heliophysics CubeSat designed to study the ionosphere at altitudes below 400km. The SORTIE mission is being developed by a team including ASTRA (lead institution), AFRL, University of Texas at Dallas (UTD), COSMIAC (Satellite Integrator), and Boston College. SORTIE will address cutting-edge science in the area of ionospheric dynamics. The SORTIE mission will address the following science questions: Q1) Discover the sources of wave-like plasma perturbations in the F-region ionosphere. Q2) Determine the relative role of dynamo action and more direct mechanical forcing in the formation of wave-like plasma perturbations. To address these questions we plan to fly a CubeSat with novel sensors that measure key plasma parameters in a circular, low to middle inclination orbit near 350-400 km altitude. The sensors include an ion velocity meter (built by UTD) and a Planar Langmuir Probe (built by AFRL). The SORTIE mission plan is to describe the distribution of wave-like structures in the plasma density of the ionospheric F-region. In doing so, the SORTIE team will determine the possible role of these perturbations in aiding the growth of plasma instabilities. SORTIE will provide (1) the initial spectrum of wave perturbations which are the starting point for the RT calculation; (2) measured electric fields which determine the magnitude of the instability growth rate near the region where plasma bubbles are generated; (3) initial observations of irregularities in plasma density which result from RT growth. SORTIE results will be used as input to PBMOD, an assimilative first-principles physical model of the ionosphere, in order to predict evolution of EPBs. In this presentation, we will review the science objectives, provide an overview of the spacecraft and instrument design, and present a concept of operations plan.

  2. Electrodynamics of solar wind-magnetosphere-ionosphere interactions

    NASA Technical Reports Server (NTRS)

    Kan, Joseph R.; Akasofu, Syun-Ichi

    1989-01-01

    The paper presents a coherent picture of fundamental physical processes in three basic elements of the solar-wind/magnetosphere/ionosphere coupling system: (1) the field-aligned potential structure which leads to the formation of auroral arcs, (2) the magnetosphere-ionosphere coupling which leads to the onset of magnetospheric substorms, and (3) the solar-wind/magnetosphere dynamo which supplies the power driving various magnetospheric processes. Process (1) is forced into existence by the loss-cone constriction effect when the upward field-aligned current density exceeds the loss-cone thermal flux limit. Substorm onset occurs when the ionosphere responds fully to the enhanced magnetospheric convection driven by the solar wind. Energy is transferred from the solar wind to the magnetosphere by a dynamo process, primarily on open field lines.

  3. All Ionospheres are not Alike: Reports from other Planets

    NASA Technical Reports Server (NTRS)

    Nagy, Andrew F.; Cravens, Thomas E.; Waite, H. J., Jr.

    1995-01-01

    Our understanding of planetary ionospheres made some progress during the last four years. Most of this progress was due to new and/or improved theoretical models, although some new data were also obtained by direct and remote sensing observations. The very basic processes such as ionization, chemical transformations and diffusive as well as convective transports are analogous in all ionospheres; the major differences are the result of factors such as different neutral atmospheres, intrinsic magnetic field strength, distance from the Sun, etc. Improving our understanding of any of the ionospheres in our solar system helps in elucidating the controlling physical and chemical processes in all of them. New measurements are needed to provide new impetus, as well as guidance, in advancing our understanding and we look forward to such information in the years ahead.

  4. Energy flow and dynamical coupling in the solar wind-magnetosphere-ionosphere system

    SciTech Connect

    Akasofu, S.I.

    1983-11-01

    A solar wind-magnetosphere-ionosphere system model is proposed which is directly driven by the solar wind-magnetosphere dynamo. The dynamo feeds the Pedersen currents to the ionosphere by generating the field-aligned currents, yielding both Joule heat and ionospheric convective motion. The field-aligned currents associated with both the Pedersen and Hall currents introduce considerable complexity into this system by generating a potential drop along the geomagnetic field lines, and it is noted that the geometry of the open region at the polar cap changes drastically as the B(z) component of the IMF becomes positive.

  5. The composition of Mars' topside ionosphere: Effects of hydrogen

    NASA Astrophysics Data System (ADS)

    Matta, Majd; Withers, Paul; Mendillo, Michael

    2013-05-01

    one-dimensional model of the Martian ionosphere is used to explore the importance of atomic and molecular hydrogen chemistry in the upper atmosphere and ionosphere. Neutral and ionized H and H2 undergo chemical reactions that lead to the production of the hydrogenated ions: H+, H2+, H3+, OH+, HCO+, ArH+, N2H+, HCO2+, and HOC+. Simulations are conducted for the cases of photochemistry only and photochemistry coupled with transport in order to asses the separate effects of plasma diffusion in the topside ionosphere. For both of these cases, the sensitivity of the ionosphere is tested for (1) molecular hydrogen abundance and (2) reaction rate, k1, for the charge exchange between H+ and H2. Results are reported for midday solar minimum conditions. We find that the ionospheric composition of Mars is sensitive to H2 abundance, but relatively insensitive to the reaction rate, k1. Depending on the conditions simulated, the topside ionosphere can contain appreciable amounts of hydrogenated species such as H3+, OH+, and HCO+. Comparisons are made with Viking ion density measurements as well as with results of other published Mars ionospheric models. Future comparisons with more extensive ion composition will be available when the Mars Atmosphere and Volatile Evolution mission arrives at Mars.

  6. Yakov Alpert: Sputnik-1 and the first satellite ionospheric experiment

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. D.; Sinelnikov, V. M.; Alpert, S. N.

    2015-06-01

    The world first scientific space experiment was carried out in 1957 during the flight of the First Artificial Earth Satellite (AES) - Sputnik-1. It was an ionospheric experiment performed at IZMIRAN under the direction of Prof. Ya.L. Alpert (1911-2010). The sunrise and sunset variations in the AES radio signal were recorded to determine the distribution of electron density in the topside ionosphere (above the maximum). The experiment demonstrated the capabilities of the satellite radio beacon method, which is now very important and widely used for studying the ionosphere. The paper describes the history and results of that experiment as well as the contribution of Ya.L. Alpert to ionospheric research. Ya.L. Alpert was one of the most famous and influential radiophysicists, the author of many fundamental studies and a number of classic books on the theory of propagation of electromagnetic waves, interaction of artificial bodies with ionospheric plasma, ionospheric radio scattering, and the use of satellite radio beacon methods for studying the ionosphere. We give in the paper some extracts from Ya.L. Alpert's research notes. They include the history of the publication of the results from recordings of the Sputnik-1 transmitter signals, and described the method of data analysis. The first scientific publication based on Sputnik-1 data is given in the abbreviated summary. At the end of the paper there is an outline of Ya.L. Alpert's scientific biography.

  7. Sputnik 1 and the First Satellite Ionospheric Experiment

    NASA Astrophysics Data System (ADS)

    Sinelnikov, Vyacheslav; Kuznetsov, Vladimir; Alpert, Svetlana

    The world's first scientific space experiment was carried out in 1957 during the flight of the first Artificial Earth Satellite (AES) - Sputnik 1. It was an ionospheric experiment performed at IZMIRAN under the direction of Prof. Ya.L.Alpert (1911-2010). The sunrise and sunset variations in the AES radio signal were recorded in order to determine the distribution of electron density in the topside ionosphere (above the maximum). The experiment demonstrated the capabilities of the satellite radio beacon method, which is now very important and widely used for studying the ionosphere. Our report submitted to the COSPAR General Assembly in Russia describes the history and results of that experiment, as well as some other contributions by Ya.L.Alpert to ionospheric research. Yakov L.Alpert was one of the most famous and influential radiophysicists of his time, the author of many fundamental studies and of a number of classic books on the theory of propagation of electromagnetic waves, interaction of artificial bodies with ionospheric plasmas, ionospheric radio scattering, and the use of satellite radio beacon methods for studying the ionosphere.

  8. First tsunami gravity wave detection in ionospheric radio occultation data

    DOE PAGES

    Coïsson, Pierdavide; Lognonné, Philippe; Walwer, Damian; Rolland, Lucie M.

    2015-05-09

    After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing themore » vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.« less

  9. First tsunami gravity wave detection in ionospheric radio occultation data

    SciTech Connect

    Coïsson, Pierdavide; Lognonné, Philippe; Walwer, Damian; Rolland, Lucie M.

    2015-05-09

    After the 11 March 2011 earthquake and tsunami off the coast of Tohoku, the ionospheric signature of the displacements induced in the overlying atmosphere has been observed by ground stations in various regions of the Pacific Ocean. We analyze here the data of radio occultation satellites, detecting the tsunami-driven gravity wave for the first time using a fully space-based ionospheric observation system. One satellite of the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) recorded an occultation in the region above the tsunami 2.5 h after the earthquake. The ionosphere was sounded from top to bottom, thus providing the vertical structure of the gravity wave excited by the tsunami propagation, observed as oscillations of the ionospheric Total Electron Content (TEC). The observed vertical wavelength was about 50 km, with maximum amplitude exceeding 1 total electron content unit when the occultation reached 200 km height. We compared the observations with synthetic data obtained by summation of the tsunami-coupled gravity normal modes of the Earth/Ocean/atmosphere system, which models the associated motion of the ionosphere plasma. These results provide experimental constraints on the attenuation of the gravity wave with altitude due to atmosphere viscosity, improving the understanding of the propagation of tsunami-driven gravity waves in the upper atmosphere. They demonstrate that the amplitude of the tsunami can be estimated to within 20% by the recorded ionospheric data.

  10. Space weather disturbances in the ionosphere-thermosphere-electrodynamics system at middle and low latitudes

    NASA Astrophysics Data System (ADS)

    Schunk, Robert

    2012-07-01

    It has been clearly established that the ionosphere-thermosphere-electrodynamics system can vary significantly from hour to hour and from day to day. The hour-to-hour variations are associated with weather disturbances, which can produce mesoscale (100-1000 km) structures and plasma irregularities. For the ionosphere, these weather disturbances include Traveling Ionospheric Disturbances (TIDs), sporadic E layers, He ^{+} layers in the topside ionosphere, descending intermediate layers, ridges of enhanced ionization (Storm Enhanced Densities), a 4-wave signature, spread-F, and equatorial plasma bubbles. For the thermosphere, the weather disturbances include upward propagating waves from the lower atmosphere (planetary, tidal and gravity waves), Traveling Atmospheric Disturbances (TADs) generated at high latitudes, storm-time O/N _{2} depletions, and neutral gas perturbations both at the terminator and in the regions containing equatorial plasma bubbles. The current state of our knowledge of weather disturbances in the middle and low latitude ionosphere-thermosphere-electrodynamics system will be reviewed.

  11. Charged particles in Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Tripathi, Sachchida

    2010-05-01

    Charged particles in Titan's ionosphere Marykutty Michael1, Sachchida Nand Tripathi1,2,3, Pratima Arya1 1Indian Institute of Technology Kanpur 2Oak Ridge Associated Universities 3NASA Goddard Space Flight Center Observations by two instruments onboard the Cassini spacecraft, Ion Neutral Mass Spectrometer (INMS) and CAssini Plasma Spectrometer (CAPS), revealed the existence of heavy hydrocarbon and nitrile species with masses of several thousand atomic mass units at altitudes of 950 - 1400 km in the atmosphere of Titan (Waite et al., 2007; Crary et al., 2009). Though these particles were believed to be molecules, they are most likely aerosols formed by the clumping of smaller molecules (Waite et al., 2009). These particles were estimated to have a density of 10-3 kg m-3 and a size of up to 256 nm. The existence of very heavy ions has also been observed by the CAPS components with a mass by charge ratio of up to 10000 (Coates et al., 2007, 2009; Sittler et al., 2009). The goal of this paper is to find out whether the so called heavy ions (or charged particles) are generated by the charge transfer of ions and electrons to the particles. The charging of these particles has been studied by using the charge balance equations that include positive ions, negative ions, electrons, neutral and charged particles. Information on the most abundant ion clusters are obtained from Vuitton et al., (2009) and Wilson and Atreya, (2004). Mass by charge ratio thus calculated will be compared with those observed by Coates et al. (2007). References: Coates AJ, et al., Discovery of heavy negative ions in Titan's ionosphere, Geophys. Res. Lett., 34:L22103, 2007. Coates AJ, et al., Heavy negative ions in titan's ionosphere: altitude and latitude dependence. Planet. Space Sci., doi:10.1016/j.pss.2009.05.009, 2009. Crary F.J., et al., Heavy ions, temperatures and winds in titan's ionosphere: Combined cassini caps and inms observations. Planet. Space Sci., doi:10.1016/j.pss.2009.09.006, 2009

  12. Energy Deposition and Redistribution in the Magnetosphere-Ionosphere System

    NASA Astrophysics Data System (ADS)

    Fok, M. H.; Khazanov, G. V.; Glocer, A.; Buzulukova, N.; Chen, S.

    2013-12-01

    The closed magnetic field region of the magnetosphere is extremely complicated and dynamic. The constituent populations of this region comprise a tightly coupled and interconnected system that must be considered in concert rather than independently. The major plasma components in this coupled system are: plasmasphere, superthermal electrons, ring current, and radiation belts. These components are moreover tightly tied to the ionosphere both through electrodynamic coupling and particle coupling. Each of these populations has distinctive features and contributes in a different way to the dynamic and energetic processes in the magnetosphere-ionosphere system. Energy from the Sun is deposited in these plasmas directly or indirectly through energy coupling mechanisms with surrounding plasma and electromagnetic fields. Our paper will focus on simulating energy deposition and redistribution in the magnetosphere-ionosphere system. Extensive data analysis and data-model comparison will be carried out to reconcile theory with measurements.

  13. Convection towers

    DOEpatents

    Prueitt, Melvin L.

    1996-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

  14. Convection towers

    DOEpatents

    Prueitt, Melvin L.

    1995-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

  15. Convection towers

    DOEpatents

    Prueitt, M.L.

    1996-01-16

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

  16. Convection towers

    DOEpatents

    Prueitt, Melvin L.

    1994-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

  17. Modeling Convection

    ERIC Educational Resources Information Center

    Ebert, James R.; Elliott, Nancy A.; Hurteau, Laura; Schulz, Amanda

    2004-01-01

    Students must understand the fundamental process of convection before they can grasp a wide variety of Earth processes, many of which may seem abstract because of the scales on which they operate. Presentation of a very visual, concrete model prior to instruction on these topics may facilitate students' understanding of processes that are largely…

  18. The ionosphere and upper atmosphere of Venus

    NASA Technical Reports Server (NTRS)

    Kumar, S.

    1975-01-01

    A summary is presented of current understanding of the upper atmosphere and ionosphere of Venus and its interaction with the solar wind, based on data from the Mariner 5 and Mariner 10 fly-bys and on far UV spectra obtained in rocket experiments. The major constituent of the upper atmosphere is CO2. Minor constituents include H, He, O, C, and CO and probably N2, Cl, and S. Although the thermal escape rate is only about 10,000/sq cm/sec, the H content in the exosphere appears to be highly variable. A prominent peak in the ionosphere profile near 140 km, appearing both on the day and nightside, is identified as an F(1) layer. An E layer and possibly an F(2) layer are present at 125 and 170 km, respectively. The dayside ionosphere may be explained in terms of the absorption of solar radiation by CO2, O, and He. The transport of ions from day to nightside may be important in the formation of the nightside ionosphere; an additional source may be needed to explain the nightside E layer. There is observational evidence that the solar wind interacts directly with the Venusian atmosphere, resulting in the formation of a bow shock. This may in part be explained by a balance at the ionopause between the solar wind ram pressure and the planetary plasma pressure.

  19. Global Response to Local Ionospheric Mass Ejection

    NASA Technical Reports Server (NTRS)

    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.

  20. Ionospheric scintillation observations over Kenyan region - Preliminary results

    NASA Astrophysics Data System (ADS)

    Olwendo, O. J.; Xiao, Yu; Ming, Ou

    2016-11-01

    Ionospheric scintillation refers to the rapid fluctuations in the amplitude and phase of a satellite signal as it passes through small-scale plasma density irregularities in the ionosphere. By analyzing ionospheric scintillation observation datasets from satellite signals such as GPS signals we can study the morphology of ionospheric bubbles. At low latitudes, the diurnal behavior of scintillation is driven by the formation of large-scale equatorial density depletions which form one to two hours after sunset via the Rayleigh-Taylor instability mechanism near the magnetic equator. In this work we present ionospheric scintillation activity over Kenya using data derived from a newly installed scintillation monitor developed by CRIRP at Pwani University (39.78°E, 3.24°S) during the period August to December, 2014. The results reveal the scintillation activity mainly occurs from post-sunset to post-midnight hours, and ceases around 04:00 LT. We also found that the ionospheric scintillation tends to appear at the southwest and northwest of the station. These locations coincide with the southern part of the Equatorial Ionization Anomaly crest over Kenya region. The occurrence of post-midnight L-band scintillation events which are not linked to pre-midnight scintillation observations raises fundamental question on the mechanism and source of electric fields driving the plasma depletion under conditions of very low background electron density.

  1. Auroral pulsations from ionospheric winds

    NASA Technical Reports Server (NTRS)

    Nakada, M. P.

    1989-01-01

    The possibility that auroral pulsations are due to oscillatory electrical circuits in the ionosphere that are driven by the negative resistance of jet stream winds is examined. For the condenser plates, the highly conducting surfaces above the edges of the jet stream are postulated. The dielectric constant of the plasma between the plates is quite large. The current that is driven perpendicular to and by the jet stream closes along the plates and through Pedersen currents in the F region above the stream. This closed loop gives the inductance and resistance for the circuit. Periods of oscillation for this circuit appear to be in the range of Pc 1 to Pc 3. In accord with observations, this circuit appears to be able to limit the brightness of pulsations.

  2. Kinetic description of ionospheric dynamics in the three-fluid approximation

    NASA Technical Reports Server (NTRS)

    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.

  3. The topside ionospheric plasma monitor (SSIES, SSIES-2 and SSIES-3) on the spacecraft of the Defense Meteorological Satellite Program (DMSP), user's guide. Volume 3: Program maintenance manual

    NASA Astrophysics Data System (ADS)

    Cornelius, J. R.; Mazzella, Andrew J., Jr.

    1994-10-01

    The objective of the Program Maintenance Manual for the DMSP SSIES flight data processing software is to provide AFSFC programming personnel with the information necessary to understand and maintain the various components of the system. This software has been specifically developed to process the SSIES-2 and SSIES-2A data formats, with provisions for retroactive adaptation to the original SSIES format and future adaptation to the SSIES-3 format. This Program Maintenance Manual describes the three programs which constitute the AFSFC SSIES processing system: BNBA, LDCON02, and APGA. The BNBA program performs data format conversions for the various SSIES telemetry data formats to generate a common file format for subsequent processing by the APGA program. The LDCON02 program generates the reference parameter file of satellite and instrument conversion constants and processing options for use by the APGA program. The APGA program performs quality evaluations and analyses of the SSIES telemetry data to create database files and reports of quantities which characterize the ionosphere.

  4. Ionospheric Flow and Escape of Ions from Titan and Venus

    NASA Technical Reports Server (NTRS)

    Hartle, R. E.; Intriligator, D. S.; Grebowsky, Joseph M.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Knowledge gained from measurements and models is used to study the high-speed plasmas interacting with the atmospheres and ionospheres of Titan and Venus. Considering the similarities of the interactions, comparative analysis is used to support the interpretations of observations made at each body. Ionospheric flow inferred to exist by analysis of measurements made from the Pioneer Venus Orbiter supports the interpretation of similar flow in the ionosphere of Titan. The concept that cold ions escape from the ionosphere of Venus is supported by the Voyager I observation that cold ions escape down the magnetic tail of Titan. Pickup O+ ion energy distributions observed at their source in the ionosheath of Venus are shown to be influenced by finite gyroradius effects. The signatures of such effects are expected to be retained as the ions move into the wakes of Titan and Venus.

  5. Estimation of HF artificial ionospheric turbulence characteristics using comparison of calculated plasma wave decay rates with the measured decay rates of the stimulated electromagnetic emission

    NASA Astrophysics Data System (ADS)

    Bareev, D. D.; Gavrilenko, V. G.; Grach, S. M.; Sergeev, E. N.

    2016-02-01

    It is shown experimentally that the relaxation time of the stimulated electromagnetic emission (SEE) after the pump wave turn off decreases when frequency of the electromagnetic wave, responsible for the SEE generation (pump wave f0 or diagnostic wave fdw) approaches 4th harmonic of the electron cyclotron frequency fce . Since the SEE relaxation is determined by the damping rate of plasma waves with the same frequency, responsible for the SEE generation, we calculated damping rates of plasma waves with ω ∼ωuh (ω is the plasma wave frequency, ωuh is the upper hybrid frequency) for frequencies close to and distant from the double resonance where ωuh ∼ 4ωce (ωce = 2 πfce). The calculations were performed numerically on the base of linear plasma wave dispersion relation at arbitrary ratio between | Δ | = ω - 4ωce and |k‖ |VTe (VTe is the electron thermal speed and k‖ is the projection of the wave vector onto the magnetic field direction. A comparison of calculation and experimental results has shown that obtained frequency dependence of the SEE decay rate is similar to the damping rate frequency dependence for plasma waves with wave vectors directed at the angles 60-70° to the magnetic field, and gives a strong hint that oblique upper hybrid plasma waves should be responsible for the SEE generation.

  6. Electric fields in the ionosphere

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.

    1975-01-01

    F-region drift velocities, measured by incoherent-scatter radar were analyzed in terms of diurnal, seasonal, magnetic activity, and solar cycle effects. A comprehensive electric field model was developed that includes the effects of the E and F-region dynamos, magnetospheric sources, and ionospheric conductivities, for both the local and conjugate regions. The E-region dynamo dominates during the day but at night the F-region and convection are more important. This model provides much better agreement with observations of the F-region drifts than previous models. Results indicate that larger magnitudes occur at night, and that daily variation is dominated by the diurnal mode. Seasonal variations in conductivities and thermospheric winds indicate a reversal in direction in the early morning during winter from south to northward. On magnetic perturbed days and the drifts deviate rather strongly from the quiet days average, especially around 13 L.T. for the northward and 18 L.T. for the westward component.

  7. Ionospheric Transmission Losses Associated with Mars-orbiting Radars

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.

    2005-01-01

    There are a number of obstacles to radar sounding of the deep Martian subsurface from orbit, including signal losses from the medium conductivity, layer reflective losses, and ground clutter. Another adverse process is signal loss as radio waves propagate through the ionospheric plasma medium. The ionosphere is a plasma consisting of free electrons, ions and neutrals that can effectively damp/attenuate radar signals via electrodneutral collisions. The effect is most severe for transmissions at lower frequencies, which, unfortunately, are also favorable transmissions for deep penetration into the subsurface.

  8. Features of steady magnetospheric convection

    NASA Technical Reports Server (NTRS)

    Yahnin, A.; Malkov, M. V.; Sergeev, V. A.; Pellinen, R. J.; Aulamo, O.; Vennergstrom, S.; Friis-Christensen, E.; Lassen, K.; Danielsen, C.; Craven, J. D.

    1994-01-01

    The large-scale patterns of ionospheric convection and particle precipitation are described during two intervals of steady magnetospheric convection (SMC) on November 24, 1981. The unique data set used in the analysis includes recordings from the worldwide network of magnetometers and all-sky cameras, global auroral images from the Dynamics Explorer (DE) 1 spacecraft, and particle precipitation data from low-altitude National Oceanic and Atmospheric Administration (NOAA) 6 and NOAA 7 spacecraft. The data show that intense magnetospheric convection continued during more than 10 hours under the steady southward interplanetary magnetic field without any distinct substorm signatures. All data sets available confirmed the stable character of the large-scale magnetospheric configuration during this period. In particular, the magnetic flux threading the polar cap was stable (within 10%) during 3.5 hours of continued DE 1 observations. The dayside cusp was located at an unusually low latitude (70 deg CGL). The nightside auroral pattern consisted of two distinct regions. The diffuse aurora in the equatorward half of the expanded (10 deg wide) auroral oval was well-separated from the bright, active auroral forms found in the vicinity of the poleward boundary of the oval. The twin-vortex convection pattern had no signature of the Harang discontinuity; its nightside 'convection throat' was spatially coincident with the poleward active auroras. This region of the auroral oval was identified as the primary site of the short-lived transient activations during the SMC intervals. The energetic particle observations show that the auroral precipitation up to its high-latitude limit is on closed field lines and that particle acceleration up to greater than 30-keV energy starts close to this limit. The isotropic boundaries of the greater than 30-keV protons and electrons were found close to each other, separating regions of discrete and diffuse precipitation. This suggests that these

  9. Convection towers

    DOEpatents

    Prueitt, M.L.

    1994-02-08

    Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode. 5 figures.

  10. Characterizing Extreme Ionospheric Storms

    NASA Astrophysics Data System (ADS)

    Sparks, L.; Komjathy, A.; Altshuler, E.

    2011-12-01

    Ionospheric storms consist of disturbances of the upper atmosphere that generate regions of enhanced electron density typically lasting several hours. Depending upon the storm magnitude, gradients in electron density can sometimes become large and highly localized. The existence of such localized, dense irregularities is a major source of positioning error for users of the Global Positioning System (GPS). Consequently, satellite-based augmentation systems have been implemented to improve the accuracy and to ensure the integrity of user position estimates derived from GPS measurements. Large-scale irregularities generally do not pose a serious threat to estimate integrity as they can be readily detected by such systems. Of greater concern, however, are highly localized irregularities that interfere with the propagation of a signal detected by a user measurement but are poorly sampled by the receivers in the system network. The most challenging conditions have been found to arise following disturbances of large magnitude that occur only rarely over the course of a solar cycle. These extremely disturbed conditions exhibit behavior distinct from moderately disturbed conditions and, hence, have been designated "extreme storms". In this paper we examine and compare the behavior of the extreme ionospheric storms of solar cycle 23 (or, more precisely, extreme storms occurring between January 1, 2000, and December 31, 2008), as represented in maps of vertical total electron content. To identify these storms, we present a robust means of quantifying the regional magnitude of an ionospheric storm. Ionospheric storms are observed frequently to occur in conjunction with magnetic storms, i.e., periods of geophysical activity as measured by magnetometers. While various geomagnetic indices, such as the disturbance storm time (Dst) and the planetary Kp index, have long been used to rank the magnitudes of distinct magnetic storms, no comparable, generally recognized index exists for

  11. Aspects of magnetosphere-ionosphere coupling in sawtooth substorms: a case study

    NASA Astrophysics Data System (ADS)

    Sandholt, P. E.; Farrugia, C. J.

    2014-10-01

    In a case study we report on repetitive substorm activity during storm time which was excited during Earth passage of an interplanetary coronal mass ejection (ICME) on 18 August 2003. Applying a combination of magnetosphere and ground observations during a favourable multi-spacecraft configuration in the plasma sheet (GOES-10 at geostationary altitude) and in the tail lobes (Geotail and Cluster-1), we monitor the temporal-spatial evolution of basic elements of the substorm current system. Emphasis is placed on activations of the large-scale substorm current wedge (SCW), spanning the 21:00-03:00 MLT sector of the near-Earth plasma sheet (GOES-10 data during the interval 06:00-12:00 UT), and magnetic perturbations in the tail lobes in relation to ground observations of auroral electrojets and convection in the polar cap ionosphere. The joint ground-satellite observations are interpreted in terms of sequential intensifications and expansions of the outer and inner current loops of the SCW and their respective associations with the westward electrojet centred near midnight (24:00 MLT) and the eastward electrojet observed at 14:00-15:00 MLT. Combined magnetic field observations across the tail lobe from Cluster and Geotail allow us to make estimates of enhancements of the cross-polar-cap potential (CPCP) amounting to ≈ 30-60 kV (lower limits), corresponding to monotonic increases of the PCN index by 1.5 to 3 mV m-1 from inductive electric field coupling in the magnetosphere-ionosphere (M-I) system during the initial transient phase of the substorm expansion.

  12. Atmosphere-Ionosphere Coupling due to Atmospheric Tides (Julius Bartels Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Forbes, Jeffrey M.

    2016-04-01

    Within the last decade, a new realization has arrived on the scene of ionosphere-thermosphere (IT) science: terrestrial weather significantly influences space weather. The aspect of space weather referred to here consists of electron density variability that translates to uncertainties in navigation and communications systems, and neutral density variability that translates to uncertainties in orbital and reentry predictions. In the present context "terrestrial weather" primarily refers to the meteorological conditions that determine the spatial-temporal distribution of tropospheric water vapor and latent heating associated with tropical convection, and the middle atmosphere disturbances associated with sudden stratosphere warmings. The net effect of these processes is a spatially- and temporally-evolving spectrum of waves (gravity waves, tides, planetary waves, Kelvin waves) that grows in amplitude with height and enters the IT system near ~100 km. Some members of the wave spectrum penetrate all the way to the base of the exosphere (ca. 500 km). Along the way, nonlinear interactions between different wave components occur, modifying the interacting waves and giving rise to secondary waves. Finally, the IT wind perturbations carried by the waves can redistribute ionospheric plasma, either through the electric fields generated via the dynamo mechanism between 100 and 150 km, or directly by moving plasma along magnetic field lines at higher levels. Additionally, the signatures of wave-driven dynamo currents are reflected in magnetic perturbations observed at the ground. This is how terrestrial atmospheric variability, through the spectrum of vertically- propagating waves that it produces, can effectively drive IT space weather. The primary objective of this Julius Bartels Lecture is to provide an overview of the global observational evidence for the IT consequences of these upward-propagating waves. In honor of Julius Bartels, who performed much research (including

  13. Reduction of electron density in the night-time lower ionosphere in response to a thunderstorm

    NASA Astrophysics Data System (ADS)

    Shao, Xuan-Min; Lay, Erin H.; Jacobson, Abram R.

    2013-01-01

    Tropospheric thunderstorms have been reported to disturb the lower ionosphere, at altitudes of 65-90km, by convective atmospheric gravity waves and by electric field changes produced by lightning discharges. Theoretical simulations suggest that lightning electric fields enhance electron attachment to O2 and reduce electron density in the lower ionosphere. Owing to the low electron density in the lower ionosphere, active probing of its electron distribution is difficult, and the various perturbative effects are poorly understood. However, it is now possible to probe the lower ionosphere in a spatially and temporally resolved manner by using remotely detected time waveforms of lightning radio signals. Here we report such observations of the night-time ionosphere above a small thunderstorm. We find that electron density in the lower ionosphere decreased in response to lightning discharges. The extent of the reduction is closely related in time and space to the rate of lightning discharges, supporting the idea that the enhanced electron attachment is responsible for the reduction. We conclude that ionospheric electron density variations corresponding to lightning discharges should be considered in future simulations of the ionosphere and the initiation of sprite discharges.

  14. RCM-E and AMIE studies of the Harang reversal formation during a steady magnetospheric convection event

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Toffoletto, Frank; Lu, Gang; Wiltberger, Michael

    2014-09-01

    This paper presents the results of a modeling study on the formation of the Harang reversal (HR) during a steady magnetospheric convection event. The Harang reversal is identified as the boundary of the northward and southward electric field in the nightside auroral zone using the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure. We simulate the event with the Rice Convection Model-Equilibrium (RCM-E) by adjusting its boundary conditions to approximately match Time History of Events and Macroscale Interactions during Substorms (THEMIS) and GOES observations in the nightside magnetosphere. Our results show that the HR is collocated with an upward region 1 field-aligned current, where converging ionospheric currents cause a southward/northward electric field on the poleward/equatorward side of the HR. Our results also indicate that the electric field reversal is slightly poleward of the ionospheric east-west current reversal and is to the northeast of the ground magnetic reversal, which is consistent with previous observations. We also test the sensitivity of the HR formation to a variety of parameters in the RCM-E simulations. We find that (1) the reduction of the flux tube entropy parameter PV5/3 near the midnight sector plays a major role in the formation of the HR; (2) a run carried out assuming uniform conductance produced the same major features as the run with more realistic precipitation-enhanced conductance; and (3) the detailed pattern of the polar cap potential distribution plays a minor role, but its dawn-dusk asymmetry significantly controls the location of the HR with respect to midnight. The RCM-E simulations also predict PV5/3 and flow distributions associated with the magnetospheric source of the HR in the plasma sheet, which can be further tested against observations.

  15. Solar-wind interaction with planetary ionospheres

    NASA Technical Reports Server (NTRS)

    Cloutier, P. A.

    1976-01-01

    Planetary encounters by numerous spacecraft have furnished information concerning the solar wind interaction with the planets Mercury, Venus, Mars, and Jupiter. While direct measurements have indicated a wide range of atmospheric densities and intrinsic magnetic field strengths, the data seem to indicate that the flow pattern around nonmagnetized or weakly magnetized planets with atmospheres optically thick at ionizing wavelengths is basically the same as that around a strongly magnetized planet's magnetosphere, such as the earth's. The planetary ionosphere apparently presents a hard obstacle to the flow, with bow shock formation required in the supersonic, super-Alfvenic flow to slow and direct most of the solar wind plasma around the planetary ionosphere. Various aspects of the interaction are examined in the context of theoretical models in an attempt to explain observed details of the interaction regions of Venus and Mars.

  16. Ionospheric delay gradient monitoring for GBAS by GPS stations near Suvarnabhumi airport, Thailand

    NASA Astrophysics Data System (ADS)

    Rungraengwajiake, Sarawoot; Supnithi, Pornchai; Saito, Susumu; Siansawasdi, Nattapong; Saekow, Apitep

    2015-10-01

    Ground-based augmentation system (GBAS) is an important augmentation system that provides the differential corrections and integrity information from the reference stations to the aircrafts for precision approach and landing. It is known that the nonuniform ionospheric characteristics called "ionospheric delay gradient" can cause the errors in differential corrections degrading the accuracy and safety level if they are undetected by the reference stations. Since the characteristics of the ionosphere are different for each region, the ionospheric delay gradient observations in equatorial and low-latitude regions are necessary for developing the suitable ionospheric threat models. The purpose of this work is to analyze the ionospheric delay gradients observed by three GPS stations near Suvarnabhumi airport in Bangkok, Thailand, which is located in the low-latitude region. The ionospheric irregularities in this region are mainly caused by the plasma bubble, which usually occurs after sunset. The GPS data with plasma bubble occurrence during the September equinox 2011 and 2012 are therefore analyzed. In addition, the data analysis procedure utilizing the rate of total electron content change index for this region is proposed. The results show that the ionospheric delay gradients observed in the west-east direction appear higher than the south-north direction, varying from 28 to 178 mm/km during plasma bubble occurrences.

  17. Toward Consistent Understanding Of The Coupling Between The Ionosphere And Plasmasphere

    NASA Astrophysics Data System (ADS)

    Maruyama, N.; Richards, P. G.; Fang, T.; Mayer, L.; Negrea, C.; Fuller-Rowell, T. J.; Codrescu, M.; Richmond, A. D.; Maute, A. I.

    2011-12-01

    The overarching objective of this study is to follow the transport and flow of plasma through the plasmasphere and ionosphere, and the exchange between them during geomagnetic storms. From the ionospheric point of view, storm time redistribution of plasma was observed in the GPS TEC [Mannuci et al 2005]. On the other hand in the plasmasphere, erosion, plumes and dynamic variation of the plasmapause were observed in the IMAGE EUV during the same Halloween storm period [Goldstein et al., 2005]. However, we do not have a good picture about how the plasma should be flowing between the ionosphere and plasmasphere during storms to explain both observations in a consistent manner. In order to address the coupling issues between the ionosphere and plasmasphere, we have developed the Ionosphere-Plasmasphere-Electrodynamics (IPE) model. It consists of a physics based model of an ionosphere and plasmasphere using the IGRF geomagnetic field configuration (APEX) with flexible spatial resolutions depending on the type of physical phenomena we would like to target. Furthermore, the global ionosphereic potential is solved self-consistently on the same grid to understand how fine structures of the ionospheric conductivity impact the electric potential, such as caused by Storm Enhanced Densities (SEDs). In this presentation, we will present TEC, a reconstruction of the IMAGE EUV, and the refilling flux along field lines obtained our model results.

  18. Convection electric fields and polar thermospheric winds.

    NASA Technical Reports Server (NTRS)

    Fedder, J. A.; Banks, P. M.

    1972-01-01

    Use of the qualitative ideas of convection electric fields over the earth's polar regions to demonstrate the importance of ion drag in establishing a thermospheric wind system. Recent measurements indicate that uniform electric fields of 10 to 40 mV/m are a regular feature of the polar-cap ionosphere. Calculations of the neutral thermospheric wind, using these measured fields in a simple ionospheric model, have been made. The time scale for motion of the neutral gas ranges from less than 1 hour at F-region heights to about 2 hours in the dynamo region of the ionosphere. It has been found that the viscosity of the atmosphere is important in determining the winds in the dynamo region. Results are given that show ion-temperature enhancements of hundreds of degrees that are due to ion-neutral frictional effects. In addition, the total deposition rate of convection energy in the polar thermosphere is shown to be of the same order of magnitude as that due to absorption of solar EUV radiation. The implications of these results for the dynamics and energetics of the thermosphere are discussed.

  19. Topside sounders as mobile ionospheric heaters

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    2006-01-01

    There is evidence that satellite-borne RF sounders can act as mobile ionospheric heaters in addition to performing topside sounding. The main objective of topside sounding is to use sounder-generated electromagnetic (em) waves to obtain ionospheric topside vertical electron-density (N(sub e) profiles. These profiles are obtained from mathematical inversions of the frequency vs. delay-time ionospheric reflection traces. In addition to these em reflection traces, a number of narrowband intense signals are observed starting at zero delay times after the transmitted pulses. Some of these signals, termed plasma resonances, appear at characteristic frequencies of the ambient medium such as at the electron cyclotron frequency f(sub ce), the harmonics nf(sub ce), the electron plasma frequency f(sub pe) and the upper-hybrid frequency f(sub uh), where (f(sub uh))(exp 2) = (f(sub ce))(exp 2) + (f(sub pe))(exp 2) . These signals have been attributed to the oblique echoes of sounder-generated electrostatic (es) waves. These resonances provide accurate in situ f(sub pe) and f(sub ce) values which, in turn, lead to accurate N(sub e) and [B] values where B is the ambient magnetic field. Resonances are also observed between the nf(sub ce) harmonics both above and below f(sub uh). The former, known as the Qn plasma resonances, are mainly attributed to the matching of the wave group velocity of sounder-generated (Bernstein-mode) es waves to the satellite velocity. The frequency spectrum of these waves in the magnetosphere can be used to detect non-Maxwellian electron velocity-distributions. In addition, these resonances also exhibit components that appear to be the result of plasma emissions stimulated by the sounder pulses. The plasma resonances observed between the nf(sub ce) harmonics and below f(sub uh), known as the Dn plasma resonances, are entirely attributed to such sounder-stimulated plasma emissions. There are other sounder-stimulated plasma phenomena that also fall into

  20. The Ptolemaic Approach to Ionospheric Electrodynamics

    NASA Astrophysics Data System (ADS)

    Vasyliunas, V. M.

    2010-12-01

    The conventional treatment of ionospheric electrodynamics (as expounded in standard textbooks and tutorial publications) consists of a set of equations, plus verbal descriptions of the physical processes supposedly represented by the equations. Key assumptions underlying the equations are: electric field equal to the gradient of a potential, electric current driven by an Ohm's law (with both electric-field and neutral-wind terms), continuity of current then giving a second-order elliptic differential equation for calculating the potential; as a separate assumption, ion and electron bulk flows are determined by ExB drifts plus collision effects. The verbal descriptions are in several respects inconsistent with the equations; furthermore, both the descriptions and the equations are not compatible with the more rigorous physical understanding derived from the complete plasma and Maxwell's equations. The conventional ionospheric equations are applicable under restricted conditions, corresponding to a quasi-steady-state equilibrium limit, and are thus intrinsically incapable of answering questions about causal relations or dynamic developments. Within their limited range of applicability, however, the equations are in most cases adequate to explain the observations, despite the deficient treatment of plasma physics. (A historical precedent that comes to mind is that of astronomical theory at the time of Copernicus and for some decades afterwards, when the Ptolemaic scheme could explain the observations at least as well if not better than the Copernican. Some of the verbal descriptions in conventional ionospheric electrodynamics might be considered Ptolemaic also in the more literal sense of being formulated exclusively in terms of a fixed Earth.) I review the principal differences between the two approaches, point out some questions where the conventional ionospheric theory does not provide unambiguous answers even within its range of validity (e.g., topside and

  1. Convective equilibrium and mixing-length theory for stellarator reactors

    SciTech Connect

    Ho, D.D.M.; Kulsrud, R.M.

    1985-09-01

    In high ..beta.. stellarator and tokamak reactors, the plasma pressure gradient in some regions of the plasma may exceed the critical pressure gradient set by ballooning instabilities. In these regions, convective cells break out to enhance the transport. As a result, the pressure gradient can rise only slightly above the critical gradient and the plasma is in another state of equilibrium - ''convective equilibrium'' - in these regions. Although the convective transport cannot be calculated precisely, it is shown that the density and temperature profiles in the convective region can still be estimated. A simple mixing-length theory, similar to that used for convection in stellar interiors, is introduced in this paper to provide a qualitative description of the convective cells and to show that the convective transport is highly efficient. A numerical example for obtaining the density and temperature profiles in a stellarator reactor is given.

  2. The Tordo 1 polar cusp barium plasma injection experiment

    NASA Technical Reports Server (NTRS)

    Wescott, E. M.; Stenbaek-Nielsen, H. C.; Davis, T. N.; Jeffries, R. A.; Roach, W. H.

    1978-01-01

    In January 1975, two barium plasma injection experiments were carried out with rockets launched into the upper atmosphere where field lines from the dayside cusp region intersect the ionosphere. The Tordo 1 experiment took place near the beginning of a worldwide magnetic storm. It became a polar cap experiment almost immediately as convection perpendicular to the magnetic field moved the fluorescent plasma jet away from the cusp across the polar cap in an antisunward direction. Convection across the polar cap with an average velocity of more than 1 km/s was observed for nearly 40 min until the barium flux tubes encountered large electron fields associated with a poleward bulge of the auroral oval near Greenland. Prior to the encounter with the aurora near Greenland there is evidence of upward acceleration of the barium ions while they were in the polar cap. The three-dimensional observations of the plasma orientation and motion give an insight into convection from the cusp region across the polar cap, the orientation of the polar cap magnetic field lines out to several earth radii, the causes of polar cap magnetic perturbations, and parallel acceleration processes.

  3. Ionospheric Scintillation Explorer (ISX)

    NASA Astrophysics Data System (ADS)

    Iuliano, J.; Bahcivan, H.

    2015-12-01

    NSF has recently selected Ionospheric Scintillation Explorer (ISX), a 3U Cubesat mission to explore the three-dimensional structure of scintillation-scale ionospheric irregularities associated with Equatorial Spread F (ESF). ISX is a collaborative effort between SRI International and Cal Poly. This project addresses the science question: To what distance along a flux tube does an irregularity of certain transverse-scale extend? It has been difficult to measure the magnetic field-alignment of scintillation-scale turbulent structures because of the difficulty of sampling a flux tube at multiple locations within a short time. This measurement is now possible due to the worldwide transition to DTV, which presents unique signals of opportunity for remote sensing of ionospheric irregularities from numerous vantage points. DTV spectra, in various formats, contain phase-stable, narrowband pilot carrier components that are transmitted simultaneously. A 4-channel radar receiver will simultaneously record up to 4 spatially separated transmissions from the ground. Correlations of amplitude and phase scintillation patterns corresponding to multiple points on the same flux tube will be a measure of the spatial extent of the structures along the magnetic field. A subset of geometries where two or more transmitters are aligned with the orbital path will be used to infer the temporal development of the structures. ISX has the following broad impact. Scintillation of space-based radio signals is a space weather problem that is intensively studied. ISX is a step toward a CubeSat constellation to monitor worldwide TEC variations and radio wave distortions on thousands of ionospheric paths. Furthermore, the rapid sampling along spacecraft orbits provides a unique dataset to deterministically reconstruct ionospheric irregularities at scintillation-scale resolution using diffraction radio tomography, a technique that enables prediction of scintillations at other radio frequencies, and

  4. CONVECTION REACTOR

    DOEpatents

    Hammond, R.P.; King, L.D.P.

    1960-03-22

    An homogeneous nuclear power reactor utilizing convection circulation of the liquid fuel is proposed. The reactor has an internal heat exchanger looated in the same pressure vessel as the critical assembly, thereby eliminating necessity for handling the hot liquid fuel outside the reactor pressure vessel during normal operation. The liquid fuel used in this reactor eliminates the necessity for extensive radiolytic gas rocombination apparatus, and the reactor is resiliently pressurized and, without any movable mechanical apparatus, automatically regulates itself to the condition of criticality during moderate variations in temperature snd pressure and shuts itself down as the pressure exceeds a predetermined safe operating value.

  5. Incoherent scatter radar observations of the ionosphere

    NASA Technical Reports Server (NTRS)

    Hagfors, Tor

    1989-01-01

    Incoherent scatter radar (ISR) has become the most powerful means of studying the ionosphere from the ground. Many of the ideas and methods underlying the troposphere and stratosphere (ST) radars have been taken over from ISR. Whereas the theory of refractive index fluctuations in the lower atmosphere, depending as it does on turbulence, is poorly understood, the theory of the refractivity fluctuations in the ionosphere, which depend on thermal fluctuations, is known in great detail. The underlying theory is one of the most successful theories in plasma physics, and allows for many detailed investigations of a number of parameters such as electron density, electron temperature, ion temperature, electron mean velocity, and ion mean velocity as well as parameters pertaining to composition, neutral density and others. Here, the author reviews the fundamental processes involved in the scattering from a plasma undergoing thermal or near thermal fluctuations in density. The fundamental scattering properties of the plasma to the physical parameters characterizing them from first principles. He does not discuss the observation process itself, as the observational principles are quite similar whether they are applied to a neutral gas or a fluctuating plasma.

  6. Cold ion escape from the Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Fränz, M.; Dubinin, E.; Andrews, D.; Barabash, S.; Nilsson, H.; Fedorov, A.

    2015-12-01

    We here report on new measurements of the escape flux of oxygen ions from Mars by combining the observations of the ASPERA-3 and MARSIS experiments on board the European Mars Express spacecraft. We show that in previous estimates of the total heavy ion escape flow the contribution of the cold ionospheric outflow with energies below 10 eV has been underestimated. Both case studies and the derived flow pattern indicate that the cold plasma observed by MARSIS and the superthermal plasma observed by ASPERA-3 move with the same bulk speed in most regions of the Martian tail. We determine maps of the tailside heavy ion flux distribution derived from mean ion velocity distributions sampled over 7 years. If we assume that the superthermal bulk speed derived from these long time averages of the ion distribution function represent the total plasma bulk speed we derive the total tailside plasma flux. Assuming cylindrical symmetry we determine the mean total escape rate for the years 2007-2014 at 2.8 ± 0.4 ×1025 atoms / s which is in good agreement with model estimates. A possible mechanism to generate this flux can be the ionospheric pressure gradient between dayside and nightside.

  7. Ducted electromagnetic waves in the Martian ionosphere detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar

    NASA Astrophysics Data System (ADS)

    Zhang, Zhenfei; Orosei, Roberto; Huang, Qian; Zhang, Jie

    2016-07-01

    In the data of the Mars Advanced Radar for Subsurface and Ionosphere Sounding on board the European Space Agency (ESA) mission Mars Express (MEX), a distinctive type of signals (called the "epsilon signature"), which is similar to that previously detected during radio sounding of the terrestrial F region ionosphere, is found. The signature is interpreted to originate from multiple reflections of electromagnetic waves propagating along sounder pulse-created, crustal magnetic field-aligned plasma bubbles (waveguides). The signatures have a low (below 0.5%) occurrence rate and apparent cutoff frequencies 3-5 times higher than the theoretical one for an ordinary mode wave. These properties are explained by the influence of the perpendicular ionospheric plasma density gradient and the sounder pulse frequency on the formation of waveguides.

  8. Convection Electric Field Patterns for Quiet and Disturbed Periods

    NASA Astrophysics Data System (ADS)

    Shepherd, S. G.; Cousins, E. D. P.

    2014-12-01

    Statistical models of ionospheric convection have been made using numeroustechniques and datasets. These models capture the climatology ofmagnetosphere-ionosphere coupling in the high-latitude and serve as usefulinputs to various models of the magnetosphere-ionosphere-theremosphere system.In this study, data from the Super Dual Auroral Radar Network (SuperDARN) areused to determine global-scale convection electric field patterns in thenorthern hemisphere for a variety of IMF and disturbance-level conditions.A five-year period from 2009-2013 has been chosen for this study and includesobservations that extend from the geomagnetic pole to below 50 degrees.Inclusion of data from mid-latitude and polar radars serves to augmentobservations from the 'traditional' high-latitude SuperDARN radars, extending the activity range over which global-scale patterns can be derived. Generally, a larger cross polar cap potential (CPCP) and linear dependence on the Kp index is observed in the new models, which is likely due to the more consistent observations in the polar cap and from the contribution of mid-latitude flows. Another notable difference in the new models is the extent to which westward flows are observed at lower latitudes. Sub-auroral flows and westward flows extending far into the post-midnight sector are observed at almost all activity levels. With the increased range of observations, these models represent an improvement in thedescription of ionospheric convection electric field climatology.

  9. A case study of a density structure over a vertical magnetic field region in the Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Duru, F.; Gurnett, D. A.; Diéval, C.; Morgan, D. D.; Pisa, D.; Lundin, R.

    2016-05-01

    One of the discoveries made by the radar sounder on the Mars Express spacecraft is the existence of magnetically controlled structures in the ionosphere of Mars, which result in bulges in the ionospheric electron density contours. These bulges lead in turn to oblique echoes, which show up as hyperbola-shaped features in the echograms. A hyperbola-shaped feature observed over an isolated region of strong crustal magnetic field is associated with a plasma cavity in the upper ionosphere and a corresponding density enhancement in the lower levels of the ionosphere. We suggest that along open magnetic field lines, the solar wind electrons are accelerated downward and the ionospheric ions are accelerated upward in a manner similar to the field line-driven auroral acceleration at Earth. This heating due to precipitating electrons may cause an increase in the scale height and may drive a loss of ionospheric plasma at high altitudes.

  10. A regional adaptive and assimilative three-dimensional ionospheric model

    NASA Astrophysics Data System (ADS)

    Sabbagh, Dario; Scotto, Carlo; Sgrigna, Vittorio

    2016-03-01

    A regional adaptive and assimilative three-dimensional (3D) ionospheric model is proposed. It is able to ingest real-time data from different ionosondes, providing the ionospheric bottomside plasma frequency fp over the Italian area. The model is constructed on the basis of empirical values for a set of ionospheric parameters Pi[base] over the considered region, some of which have an assigned variation ΔPi. The values for the ionospheric parameters actually observed at a given time at a given site will thus be Pi = Pi[base] + ΔPi. These Pi values are used as input for an electron density N(h) profiler. The latter is derived from the Advanced Ionospheric Profiler (AIP), which is software used by Autoscala as part of the process of automatic inversion of ionogram traces. The 3D model ingests ionosonde data by minimizing the root-mean-square deviation between the observed and modeled values of fp(h) profiles obtained from the associated N(h) values at the points where observations are available. The ΔPi values are obtained from this minimization procedure. The 3D model is tested using data collected at the ionospheric stations of Rome (41.8N, 12.5E) and Gibilmanna (37.9N, 14.0E), and then comparing the results against data from the ionospheric station of San Vito dei Normanni (40.6N, 18.0E). The software developed is able to produce maps of the critical frequencies foF2 and foF1, and of fp at a fixed altitude, with transverse and longitudinal cross-sections of the bottomside ionosphere in a color scale. fp(h) and associated simulated ordinary ionogram traces can easily be produced for any geographic location within the Italian region. fp values within the volume in question can also be provided.

  11. ASPERA/Phobos measurements of the ion outflow from the Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Lundin, R.; Zakharov, A.; Pellinen, R.; Barabasj, S. W.; Borg, H.; Dubinin, E. M.; Hultqvist, B.; Koskinen, H.; Liede, I.; Pissarenko, N.

    1990-05-01

    This report reviews the first results on the ionospheric ion outflow in the Martian magnetosphere by the Automatic Space Plasma Experiment with a Rotating Analyzer ion composition experiment on Phobos-2. The measurements show that Mars is characterized by a strong loss of plasma from its topside ionosphere. A preliminary estimate of the ionospheric outflow from Mars indicates that the planet at present is losing oxygen at a rate of about 3 x 10 to the 25th ions/s. This corresponds to an evacuation of its present total atmospheric oxygen content in less than 100 million years.

  12. Upper limits to the nightside ionosphere of Mars

    NASA Technical Reports Server (NTRS)

    Fox, J. L.; Brannon, J. F.; Porter, H. S.

    1993-01-01

    The nightside ionosphere of Mars could be produced by electron precipitation or by plasma transport from the dayside, by analogy to the Venus, but few measurements are available. We report here model calculations of upper limits to the nightside ion densities on Mars that would be produced by both mechanisms. For the auroral model, we have adopted the downward traveling portions of the electron spectra measured by the HARP instrument on the Soviet Phobos spacecraft in the Martian plasma sheet and in the magnetotail lobes. For the plasma transport case, we have imposed on a model of the nightside thermosphere, downward fluxes of O(+), C(+), N(+), NO(+) and O2(+) that are near the maximum upward fluxes that can be sustained by the dayside ionosphere. The computed electron density peaks are in the range (1.3 - 1.9) x 10 exp 4/cu cm at altitudes of 159 to 179 kin. The major ion for all the models is O2(+), but significant differences in the composition of the minor ions are found for the ionospheres produced by auroral precipitation and by plasma transport. The calculations reported here provide a guide to the data that should be acquired during a future aeronomy mission to Mars, in order to determine the sources of the nightside ionosphere.

  13. Upper limits to the nightside ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Fox, J. L.; Brannon, J. F.; Porter, H. S.

    1993-07-01

    The nightside ionosphere of Mars could be produced by electron precipitation or by plasma transport from the dayside, by analogy to the Venus, but few measurements are available. We report here model calculations of upper limits to the nightside ion densities on Mars that would be produced by both mechanisms. For the auroral model, we have adopted the downward traveling portions of the electron spectra measured by the HARP instrument on the Soviet Phobos spacecraft in the Martian plasma sheet and in the magnetotail lobes. For the plasma transport case, we have imposed on a model of the nightside thermosphere, downward fluxes of O(+), C(+), N(+), NO(+) and O2(+) that are near the maximum upward fluxes that can be sustained by the dayside ionosphere. The computed electron density peaks are in the range (1.3 - 1.9) x 10 exp 4/cu cm at altitudes of 159 to 179 kin. The major ion for all the models is O2(+), but significant differences in the composition of the minor ions are found for the ionospheres produced by auroral precipitation and by plasma transport. The calculations reported here provide a guide to the data that should be acquired during a future aeronomy mission to Mars, in order to determine the sources of the nightside ionosphere.

  14. The ionospheres of Titan and Enceladus: Data and theory

    NASA Astrophysics Data System (ADS)

    Cravens, Thomas

    Our current understanding of the ionospheres of Titan and Enceladus will be reviewed. Our knowledge of the plasma environments of these bodies has been greatly enhanced by data obtained by several instruments onboard the Cassini spacecraft including the ion and neutral mass spectrometer (INMS), the Langmuir Probe (RPWS-LP), the magnetometer (MAG), and the electron and ion spectrometers (CAPS). The major neutral species at Titan are molecular nitrogen and methane. Photoionization of these species is the main source of the dayside ionosphere, which exhibits a complex photochemistry. Electron impact ionization of the neutral atmosphere is responsible for the bulk of ion production on the nightside, although ion precipitation and redistribution of plasma by transport could contribute to the structure of the nightside ionosphere. Saturn’s icy satellite Enceladus has a neutral water plume and an associated region (that is, an ionosphere of sorts) in which the plasma is colder and chemically different than in the surrounding inner magnetosphere. Data from Cassini instruments revealed the existence of a strong interaction between Saturn’s magnetospheric plasma flow (and fields) and the neutral gas and ice grains in the plume. The INMS detected H3O+ ions rather than water ions in the plume and CAPS measured negative ion species over a large mass range. The physical processes taking place in the plume will be reviewed.

  15. Broadband meter-wavelength observations of ionospheric scintillation

    NASA Astrophysics Data System (ADS)

    Fallows, R. A.; Coles, W. A.; McKay-Bukowski, D.; Vierinen, J.; Virtanen, I. I.; Postila, M.; Ulich, Th.; Enell, C.-F.; Kero, A.; Iinatti, T.; Lehtinen, M.; Orispää, M.; Raita, T.; Roininen, L.; Turunen, E.; Brentjens, M.; Ebbendorf, N.; Gerbers, M.; Grit, T.; Gruppen, P.; Meulman, H.; Norden, M. J.; de Reijer, J.-P.; Schoenmakers, A.; Stuurwold, K.

    2014-12-01

    Intensity scintillations of cosmic radio sources are used to study astrophysical plasmas like the ionosphere, the solar wind, and the interstellar medium. Normally, these observations are relatively narrow band. With Low-Frequency Array (LOFAR) technology at the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) station in northern Finland we have observed scintillations over a three-octave bandwidth. "Parabolic arcs," which were discovered in interstellar scintillations of pulsars, can provide precise estimates of the distance and velocity of the scattering plasma. Here we report the first observations of such arcs in the ionosphere and the first broadband observations of arcs anywhere, raising hopes that study of the phenomenon may similarly improve the analysis of ionospheric scintillations. These observations were made of the strong natural radio source Cygnus-A and covered the entire 30-250 MHz band of KAIRA. Well-defined parabolic arcs were seen early in the observations, before transit, and disappeared after transit although scintillations continued to be obvious during the entire observation. We show that this can be attributed to the structure of Cygnus-A. Initial results from modeling these scintillation arcs are consistent with simultaneous ionospheric soundings taken with other instruments and indicate that scattering is most likely to be associated more with the topside ionosphere than the F region peak altitude. Further modeling and possible extension to interferometric observations, using international LOFAR stations, are discussed.

  16. Chemistry in the Thermosphere and Ionosphere.

    ERIC Educational Resources Information Center

    Roble, Raymond G.

    1986-01-01

    An informative review which summarizes information about chemical reactions in the thermosphere and ionosphere. Topics include thermal structure, ultraviolet radiation, ionospheric photochemistry, thermospheric photochemistry, chemical heating, thermospheric circulation, auroral processes and ionospheric interactions. Provides suggested followup…

  17. Investigation of Wave Excitation by Conventional and Parametric Antennas in the Ionospheric Plasma Using Three-Dimensional Particle-in-Cell Simulations

    NASA Astrophysics Data System (ADS)

    Main, D. S.

    2015-12-01

    Conventional antennas immersed in a cold, magnetized plasma (CMP) and operating in the very low frequency (VLF) range (e.g. loop and dipole antennas) excite plasma waves that are predominantly electrostatic. For example, loop antennas excited in the frequency range ωLH < ω < ωce (where ωLH and ωce are the lower hybrid and electron cyclotron frequencies) produce electrostatic lower oblique resonance (LOR) waves. Likewise a dipole antenna excited in the frequency range ωci < Ω < ωLH (where ωci is the ion cyclotron frequency) produce electrostatic ion acoustic (IA) type density perturbations. The goal of our research is to increase power radiated into the electromagnetic part of the VLF wave spectrum, specifically into electromagnetic Whistler waves. These waves are generated in a CMP due to a nonlinear parametric coupling of the strong quasi-electrostatic electric fields from the loop antenna and the density perturbations from the dipole antenna. Therefore, a parametric antenna is made by parametrically coupling these two waves. Because EM Whistler waves are effective sources of pitch angle diffusion, one application of a parametric antenna includes radiation belt remediation in Earth's space environment. In this poster we show electric field patterns from the loop and dipole antennas and the EM spectrum excited due to the parametric interaction.

  18. A Campaign to Study Equatorial Ionospheric Phenomena over Guam

    NASA Astrophysics Data System (ADS)

    Habash Krause, L.; Balthazor, R.; Dearborn, M.; Enloe, L.; Lawrence, T.; McHarg, M.; Petrash, D.; Reinisch, B. W.; Stuart, T.

    2007-05-01

    With the development of a series of ground-based and space-based experiments, the United States Air Force Academy (USAFA) is in the process of planning a campaign to investigate the relationship between equatorial ionospheric plasma dynamics and a variety of space weather effects, including: 1) ionospheric plasma turbulence in the F region, and 2) scintillation of radio signals at low latitudes. A Digisonde Portable Sounde