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Sample records for ionospheric plasma convection

  1. New SuperDARN Radar Capabilities for Observing Ionospheric Plasma Convection and ITM Coupling in the Mid-Latitude Ionosphere

    NASA Astrophysics Data System (ADS)

    Ruohoniemi, J. M.; Baker, J. B.; Greenwald, R. A.; Clausen, L. B.; Shepherd, S. G.; Bristow, W. A.; Talaat, E. R.; Barnes, R. J.

    2010-12-01

    Within the past year the first pair of SuperDARN radars funded under the NSF MSI program has become operational at a site near Hays, Kansas. The fields of view of the co-located radars are oriented to provide common-volume observations with two existing radars in Virginia (Wallops, Blackstone) and two MSI radars under construction in Oregon (Christmas Valley). The emerging mid-latitude radar chain will complement the existing SuperDARN coverage at polar cap and auroral latitudes within North America. The mid-latitude radars observe the expansion of auroral effects during disturbed periods, subauroral polarization streams, and small-scale ionospheric irregularities on the nightside that open a window on the plasma drifts and electric fields of the quiet-time subauroral ionosphere. They also measure neutral winds at mesospheric heights and the propagation of ionospheric disturbances due to the passage of atmospheric gravity waves. The new radar capabilities provide unprecedented views of ITM processes in the subauroral ionosphere with applications to studies of ionospheric electric fields, ion-neutral coupling, atmospheric tides and planetary waves, ionospheric plasma structuring and plasma instability. In this talk we describe the new capabilities and the potential for providing large-scale context for related ITM measurements over North America. We present the first high-resolution two-dimensional maps of ionospheric plasma convection at mid-latitudes as generated from common-volume observations with the Hays and Blackstone radars.

  2. 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.

  3. Studies of plasma irregularities and convection in the polar ionosphere using HILAT, SABRE and EISCAT

    NASA Astrophysics Data System (ADS)

    Jones, Tudor B.; Leicester, Mark

    1990-12-01

    The average ionospheric convection patterns measured by SABRE as a function of IMF Bz and By were computed. The convection of SABRE geomagnetic latitudes about 61 to 66 N is seen to be stronger during negative Bz. Asymmetries in the convection pattern are detected as a function of By. The nightside flow reversal is found to occur at earlier local times for positive By. The duration of purely equatorward flow in this reversal region is found to be longer during intervals of negative By. Although there are only a few clear examples, the ionospheric convection associated with the morning reversal, i.e., the cusp region, it also dependent upon the sign of By. A period of anomalous westward flow occurs at the higher latitudes prior to the reversal during positive By conditions. The occurrence of backscatter during the complete interval of SABRE operations was also investigated. Relating the mean daily backscatter power with various interplanetary parameters such as vBz, v-sq Bz and epsilon indicates that the sign of Bz is the most important parameter. The mean power is considerably higher during intervals of southward Bz. A study which attempted to relate the occurrence of E-region irregularities to the location of the F-region trough was undertaken. No clear relationship appears to exist between these two phenomena based upon data from SABRE and EISCAT taken over a 36 month interval. Finally, the height of the E-region irregularities measured with the SADIE system was investigated.

  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. Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitations, 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.; Persoon, A. M.; Scudder, J. D.; Maynard, N. C.; Mozer, F. S.; Brittnacher, M. J.; Nagai, T.

    1997-01-01

    The POLAR satellite often observes upflowing ionospheric ions (UFls) in and near the auroral oval on southern perigee (approximately 5000 km altitude) passes. We present the UFI features observed by the thermal ion dynamics experiment (TIDE) and the toroidal imaging mass-angle spectrograph (TIMAS) in the dusk-dawn sector under two different geomagnetic activity conditions in order to elicit their relationships with auroral forms, wave emissions, and convection pattern from additional POLAR instruments. During the active interval, the ultraviolet imager (UVI) observed a bright discrete aurora on the dusk side after the substorm onset and then observed a small isolated aurora form and diffuse auroras on the dawn side during the recovery phase. The UFls showed clear conic distributions when the plasma wave instrument (PWI) detected strong broadband wave emissions below approximately 10 kHz, while no significant auroral activities were observed by UVI. At higher latitudes, the low-energy UFI conics gradually changed to the polar wind component with decreasing intensity of the broadband emissions. V-shaped auroral kilometric radiation (AKR) signatures observed above approximately 200 kHz by PWI coincided with the region where the discrete aurora and the UFI beams were detected. The latitude of these features was lower than that of the UFI conics. During the observations of the UFI beams and conics, the lower-frequency fluctuations observed by the electric field instrument (EFI) were also enhanced, and the convection directions exhibited large fluctuations. It is evident that large electrostatic potential drops produced the precipitating electrons and discrete auroras, the UFI beams, and the AKR, which is also supported by the energetic plasma data from HYDRA. Since the intense broadband emissions were also observed with the UFIs. the ionospheric ions could be energized transversely before or during the parallel acceleration due to the potential drops.

  6. Drift of Auroral Absorption and Ionospheric Convection

    NASA Astrophysics Data System (ADS)

    Makarevitch, R. A.; Honary, F.; McCrea, I. W.; Howells, V. S.

    2004-12-01

    We develop a method for quasi-continuous monitoring of the particle precipitation regions using the cosmic noise absorption (CNA) data from an imaging riometer. The method does not require vast computational resources nor does it involve excessive manual sifting through the data. The horizontal absorption drift velocity is estimated from the regression lines to positions of the maxima in the two-dimensional absorption intensity images for each individual region of enhanced CNA (absorption patches). The absorption drift velocity estimates from a 7x7-beam Imaging Riometer for Ionospheric Studies (IRIS) in Kilpisjarvi are compared with the electrojet plasma flows deduced from magnetic perturbations recorded by the Kilpisjarvi magnetometer as well as with the tristatic ion drift velocities in the F region (for one event) measured by the EISCAT radar facility within the IRIS field of view (FoV). A reasonable agreement was found between the directions of absorption drift and ionospheric convection both in point-by-point comparisons and in terms of direction reversal timings. The absorption patches of lower intensity appear to have smaller drift velocities and to be associated with weaker magnetic perturbations. Based on our observations, we interpret the relatively slow motions of the auroral absorption as associated with the ExB drift of the entire magnetic flux tube as opposed to the gradient-curvature drift of energetic electrons injected into the ionosphere at the substorm onset. Since the absorption intensity in beam 16 of IRIS, the beam closest to that of EISCAT at 90 km, was found to correlate well with the height-integrated Hall conductivity due to particle precipitation inferred from the EISCAT density measurements, we also assess the conductivity gradient effects on the agreement between the convection measurements by different techniques by considering the gradients of the absorption intensity within the IRIS FoV.

  7. Studies of the high latitude ionospheric convection

    NASA Astrophysics Data System (ADS)

    Drake, Kelly Ann

    The electrostatic potential distribution in the high latitude ionosphere is representative of the response of the ionosphere magnetosphere system to drivers in the solar wind and conditions in the interplanetary medium. The cross polar cap potential drop, used as a single parameter to describe the global distribution of electrostatic potential, often serves as an input driver for various magnetospheric and space weather models. For a given solar wind condition the cross polar cap potential drop derived from satellite measurements of the electric field, or ion drift in the ionosphere, are observed to have a significant variation, often on the order of thirty percent or greater. Such a large variability could influence the uncertainty of results from models that utilize this electrostatic potential drop as an input, so a further understanding of the sources and organization of these uncertainties will improve the specification itself and the confidence limits of the observations. Sources of this variability are investigated using two years (2000-2001) of ionospheric plasma flow data provided by the DMSP F13 and F15 satellites to calculate the cross polar cap potential drop, along with solar wind data from the ACE satellite in order to explore the behavior of this potential in response to a wide range of interplanetary magnetic field (IMF) conditions during southward IMF (BZ ≤ 0). A variety of IMF conditions are examined to show how the stability of the IMF and the solar wind speed over both short and long time periods affects variations in the cross polar cap potential drop. The most interesting discovery is that, even during steady state IMF conditions, the largest amount of variability is caused by the displacement of the satellite track with respect to the extrema in potential at the center of the two convection cells in the high-latitude region, especially when the displacement is caused by substorm activity. Included is a study of the average properties of the electrostatic potential drop and its relationship to particle precipitation boundaries across the ionospheric projection of the low latitude boundary layer and the interplanetary electric field.

  8. An ionospheric convection signature of antiparallel reconnection

    NASA Astrophysics Data System (ADS)

    Coleman, Iain J.; Chisham, Gareth; Pinnock, Mike; Freeman, Mervyn P.

    2001-12-01

    This paper sets out a critical test of the antiparallel merging hypothesis. For the conflicting theories of antiparallel and subsolar reconnection, we model the location of reconnection regions on the dayside magnetopause, their ionospheric footprints, and the resulting ionospheric convection patterns. We show that antiparallel reconnection, under particular seasonal and solar wind conditions, gives rise to a distinctive ionospheric convection signature. Specifically, around midwinter with a quasi-steady solar wind and IMF Bz<0 and |By|~|Bz|, we predict equatorward flow in the noon sector with poleward flow either side of noon if the antiparallel merging hypothesis is correct. In contrast, we predict poleward flow in the noon sector in midwinter under these solar wind conditions if the subsolar reconnection hypothesis is correct and in other seasons under both hypotheses. We go on to present radar and spacecraft data for an interval which satisfies the above seasonal and solar wind criteria, demonstrating that the convection signature of antiparallel merging is present. This is not consistent with the subsolar merging hypothesis.

  9. Magnetospheric convection and the high-latitude F2 ionosphere

    NASA Technical Reports Server (NTRS)

    Knudsen, W. C.

    1974-01-01

    Behavior of the polar ionospheric F layer as it is convected through the cleft, over the polar cap, and through the nightside F layer trough zone is investigated. Passage through the cleft adds approximately 200,000 ions per cu cm in the vicinity of the F2 peak and redistributes the ionization above approximately 400-km altitude to conform with an increased electron temperature. The redistribution of ionization above 400-km altitude forms the 'averaged' plasma ring seen at 1000-km altitude. The F layer is also raised by approximately 20 km in altitude by the convection electric field. The time required for passage across the polar cap (25 deg) is about the same as that required for the F layer peak concentration to decay by e. The F layer response to passage through the nightside soft electron precipitation zone should be similar to but less than its response to passage through the cleft.

  10. Statistical features of the high-latitude ionospheric convection structure associated with enhanced solar wind fluctuations

    NASA Astrophysics Data System (ADS)

    Kim, H.; Lyons, L. R.; Ruohoniemi, J. M.; Frissell, N. A.

    2012-12-01

    While the IMF and solar wind dynamic pressure almost certainly play larger roles under most conditions, evidence has been recently found that Ultra Low Frequency (ULF) wave power in the solar wind has an additional substantial effect on the strength of convection within the polar caps, and on the nightside within both the aurora ionosphere and the plasma sheet. An initial study shows that the convection flows under enhanced solar wind fluctuations often appear to be more structured, with localized strong vortical features, than the convection under steady solar wind conditions. In this work, we statistically examine characteristic features of the ionospheric convection structure in terms of vortex patterns and how they are related to the convection enhancements during periods of enhanced solar wind fluctuations. Specifically, we examine whether enhanced solar wind ULF power will drive localized turbulence within enhanced convection cells while it increases convection strength at the same time. The results of this study will provide evidence for how solar wind ULF fluctuations can contribute to the solar wind energy transfer to the magnetosphere-ionosphere system. To determine the features of 2-D convection structure, we analyze the large-scale global convection maps derived from the SuperDARN observations with extensive radar echo coverage over a large portion of the high latitude ionosphere. Wind and ACE data are used for examination of solar wind and IMF conditions.

  11. Theoretical study of the high-latitude ionosphere's response to multicell convection patterns

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    A time-dependent three-dimensional model of the high-latitude ionosphere is used to study the characteristic ionospheric signatures associated with two-, three-, and four-cell plasma convection patterns. It is found that, for two-cell convection, the antisunward flow of plasma from the dayside into the polar cap acts to maintain the densities in this region in winter. For four-cell convection, the two additional convection cells in the polar cap are in darkness most of the time, and the resulting O(+) decay acts to produce twin polar holes that are separated by a sun-aligned ridge of enhanced ionization due to theta-auroral precipitation. For three-cell convection, only one polar hole forms in the total electron density, and an additional O(+) depletion region develops near noon. In this region there are strong electric fields, high ion temperatures, and an enhanced rate of O(+) - NO(+) conversion.

  12. The influence of IMF clock angle timescales on the morphology of ionospheric convection

    NASA Astrophysics Data System (ADS)

    Grocott, A.; Milan, S. E.

    2014-07-01

    We exploit a database of high-latitude ionospheric electric potential patterns, derived from radar observations of plasma convection in the Northern Hemisphere from the years 2000-2006, to investigate the timescales of interplanetary magnetic field (IMF) control of ionospheric convection and associated magnetospheric dynamics. We parameterize the convection observations by IMF clock angle, ? (the angle between geocentric solar magnetic (GSM) north and the projection of the IMF vector onto the GSM Y-Z plane), and by an IMF timescale, ?B (the length of time that a similar clock angle has been maintained prior to the convection observations being made). We find that the nature of the ionospheric convection changes with IMF clock angle, as expected from previous time-averaged studies, and that for ?B30 min, the convection patterns closely resemble their time-averaged counterparts. However, as ?B increases we find that the convection evolves away from the time-averaged patterns to reveal modified characteristic flow features. We discuss these findings in terms of solar wind-magnetosphere-ionosphere coupling and consider their implications for understanding the time-dependent nature of magnetospheric dynamics.

  13. An interplanetary magnetic field dependent model of the ionospheric convection electric field

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    An IMF-dependent model of the magnetospheric electric field at ionospheric altitudes has been developed based on published observations, qualitative models, and a limited understanding of the electric field source. The empirical inputs are discussed, and the model is presented in an ionospheric convection situation where corotation is an important ingredient. This leads to a description of sunward ionospheric plasma transport in the polar cap for northward IMF orientations. The validity of the model is discussed, and areas in which more empirical results are required are specified.

  14. 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.

  15. Polar Cap Potential Saturation and Ionospheric Convection Patterns during Superstorms

    NASA Astrophysics Data System (ADS)

    Du, A.; Sun, W.; Tsurutani, B.

    2012-12-01

    Five super intense magnetic storms (with minimum Dst < -200 nT) were examined to investigate the relationship between polar cap potential (PCP) saturation and ionospheric convection patterns. A quantitative method was used to determine whether or not PCP was saturated by applying both linear and nonlinear (exponential) fits for each event. The results showed that PCP saturation occurred for two of five. The two events with saturation had distorted ionospheric convection patterns (D-CONV) with asymmetric vortices, while for the other three events without PCP saturation had well-known standard convection (S-CONV) with quasi-symmetric twin vortices. The authors conclude that sporadic midnight sector substorm electric fields may contribute to the asymmetric convection patterns and PCP saturation, in agreement with previous speculations. Further analyses are needed to confirm this hypothesis.t;

  16. Electrodynamics of the equatorial evening ionosphere: 2. Conductivity influences on convection, current, and electrodynamic energy flow

    NASA Astrophysics Data System (ADS)

    Richmond, A. D.; Fang, T.-W.

    2015-03-01

    We analyze how the evening equatorial plasma vortex and the prereversal enhancement (PRE) of the vertical drift are influenced by the distributions of conductivity in the E and F regions in relation to the wind, through numerical simulations with the thermosphere-ionosphere-electrodynamics general circulation model coupled with the global ionosphere-plasmasphere model. The nightside electric potential satisfies an approximate minimization principle that unifies the connection of the horizontal and vertical components of plasma convection to the wind and conductivity distributions. The relative roles of E and F region conductivities on the convection and current closure are clarified. Evening time F region zonal winds at latitudes that encompass the equatorial ionization anomaly (EIA) region provide the main energy source to drive the convection, including the PRE. The E region helps regulate both the meridional and the zonal convection through drag on the meridional convection associated with Cowling current. For large nighttime E region conductivities, additional drag on the zonal convection comes from the Pedersen conductance. The minimization principle favors meridional plasma inflow to the EIA region from lower rather than higher magnetic apex heights, so long as the E region Cowling conductance is not too large. This upward/poleward inflow maximizes on field lines that traverse the lower F layer near the equatorward edge of the EIA region, producing a PRE with maximum vertical velocity within the equatorial F layer.

  17. Sensitivity of Low-Latitude Ionospheric Convection in the Evening to E-Region Conductivity

    NASA Astrophysics Data System (ADS)

    Richmond, A. D.; Fang, T. W.; Maute, A. I.

    2014-12-01

    Modeling of low-latitude ionospheric electrodynamics reveals a sensitivity of ExB convection in the evening to E-region conductivity. This sensitivity is explained in terms of two related but distinct effects. First, meridional E-region currents associated with Pedersen conductivity partially balance meridional F-region dynamo currents. Since the F-region current density depends more on the pressure-gradient force driving the wind than on the E-region conductivity, changes in the latter provoke an inversely related change in the electric field and plasma convection velocity, even though the relative contribution of the E region to the field-line-integrated conductivity may be small as compared with the F region contribution. The second way in which night-time E-region conductivity affects the evening plasma convection is through regulation of the zonal electric field and vertical/meridional plasma convection. In this case it is the E-region Cowling conductance, rather than the Pedersen conductance, that comes into play. Vertical convection through the E region in the early evening, associated with the pre-reversal enhancement of the vertical drift, is associated with zonal Cowling current that dissipates a relatively large amount of electromagnetic energy, and therefore exerts a drag on the evening plasma convection. This presentation quantifies the sensitivity of the convection to the night-time E-region conductivity, and shows how the convection distribution tends to obey a minimization principle.

  18. An extended TRANSCAR model including ionospheric convection: simulation of EISCAT observations using inputs from AMIE

    NASA Astrophysics Data System (ADS)

    Blelly, P.-L.; Lathuillère, C.; Emery, B.; Lilensten, J.; Fontanari, J.; Alcaydé, D.

    2005-02-01

    The TRANSCAR ionospheric model was extended to account for the convection of the magnetic field lines in the auroral and polar ionosphere. A mixed Eulerian-Lagrangian 13-moment approach was used to describe the dynamics of an ionospheric plasma tube. In the present study, one focuses on large scale transports in the polar ionosphere. The model was used to simulate a 35-h period of EISCAT-UHF observations on 16-17 February 1993. The first day was magnetically quiet, and characterized by elevated electron concentrations: the diurnal F2 layer reached as much as 1012m-3, which is unusual for a winter and moderate solar activity (F10.7=130) period. An intense geomagnetic event occurred on the second day, seen in the data as a strong intensification of the ionosphere convection velocities in the early afternoon (with the northward electric field reaching 150mVm-1) and corresponding frictional heating of the ions up to 2500K. The simulation used time-dependent AMIE outputs to infer flux-tube transports in the polar region, and to provide magnetospheric particle and energy inputs to the ionosphere. The overall very good agreement, obtained between the model and the observations, demonstrates the high ability of the extended TRANSCAR model for quantitative modelling of the high-latitude ionosphere; however, some differences are found which are attributed to the precipitation of electrons with very low energy. All these results are finally discussed in the frame of modelling the auroral ionosphere with space weather applications in mind.

  19. 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.

  20. SuperDARN convection and Sondrestrom plasma drift

    NASA Astrophysics Data System (ADS)

    Xu, L.; Koustov, A. V.; Thayer, J.; McCready, M. A.

    Plasma convection measurements by the Goose Bay and Stokkseyri SuperDARN radar pair and the Sondrestrom incoherent scatter radar are compared in three different ways, by looking at the line-of-sight (l-o-s) velocities, by comparing the SuperDARN vectors and corresponding Sondrestrom l-o-s velocities and by comparing the end products of the instruments, the convection maps. All three comparisons show overall reasonable agreement of the convection measurements though the data spread is significant and for some points a strong disagreement is obvious. The convection map comparison shows 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). On average, both effects do not exceed 35%. Data indicate that inconsistencies between the two data sets occur largely at times of fast temporal variations of the plasma drift and for strongly irregular flow ac-cording to the SuperDARN convection maps. These facts indicate that the observed discrepancies are in many cases a result of the different spatial and temporal resolutions of the instruments.Key words. Ionosphere (ionospheric irregularities; plasma convection; polar ionosphere)

  1. 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.

  2. 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.

  3. Plasma conductivity for Comet Halley ionosphere

    SciTech Connect

    Buti, B.; Eviatar, A.

    1989-01-01

    Observational as well as semitheoretical magnetic field profiles have been used to derive self-consistently the plasma conductivity profiles for the ionosphere of Comet Halley. The characteristic diffusion length for the field, according to the present model, is about 28 km; this is in very good agreement with the Giotto spacecraft observations. It is shown that ideal MHD as well as constant conductivity models are not appropriate for the study of dynamical structure of the Halley's ionosphere. 11 references.

  4. The theta aurora and ionospheric flow convection: Polar ultraviolet imager and SuperDARN radar observations

    NASA Astrophysics Data System (ADS)

    Liou, K.; Ruohoniemi, J. M.; Newell, P. T.; Meng, C. I.

    2003-12-01

    We report results from a case study of the theta aurora that occurred during a magnetic cloud event on November 8, 2000. The interplanetary magnetic field (IMF) was strongly northward for more than 12 hours, while the y-component of IMF changed signs several times. Auroral images from the Ultraviolet Imager on board the Polar satellite show clear instances of theta auroras during the prolonged northward IMF period. This event provides a good opportunity for testing current models of theta aurora generation and evolution. We examine in situ particle data from the DMSP satellites to find magnetospheric source regions responsible for the theta auroras. We also examine ionospheric plasma flow convection data from the SuperDARN radar network to study relationships between the ionospheric plasma flow pattern and the location of the theta auroras. Our results clearly indicate that the theta aurora bar, at least on nightside, was located in a region of anti-sunward convecting flow. This is not consistent with the current view that theta auroras reside in regions of closed field lines and hence in regions of sunward convecting flow. Implication of the new findings will be discussed.

  5. Multiring probe in a flowing ionospheric plasma.

    NASA Technical Reports Server (NTRS)

    Sheldon, J. W.; Stone, N. H.

    1973-01-01

    Description of a multiring probe placed in an ionospheric flow simulation chamber utilizing a modified Kaufman ion engine for its plasma source. The pertinent details of the probe design, instrumentation, and operating procedures are discussed, and the preliminary results obtained are presented.

  6. Statistics of plasma sheet convection

    NASA Astrophysics Data System (ADS)

    Juusola, L.; Østgaard, N.; Tanskanen, E.

    2011-08-01

    Determining the characteristics of plasma sheet convection and their response to changes in various solar wind parameters is important for understanding the energy and mass transport, as well as disturbance propagation, through geospace. We use 15 years of data obtained by Geotail, Cluster, and THEMIS to study statistically the characteristics of plasma sheet flows and the effect of the interplanetary magnetic field (IMF) on the convection. We find that plasma sheet convection is dominated by slow speed (<100 km/s) flows that circulate around Earth on both sides toward the dayside. With increasing flow speed the sunward component of the flow velocity becomes more pronounced such that flows with V > 500 km/s are directed almost purely sunward. Both IMF By and IMF Bz are observed to penetrate the plasma sheet. During southward IMF conditions, a channel of increased Bz is created in the nightside around the aberrated midnight axis. We suggest that the channel is caused by dipolarization and magnetic flux pileup related to fast flows. The nightside region of highest mean flow speed is located more duskward during dawnward IMF conditions than during duskward IMF conditions. For plasma sheet flows with speeds higher than 100 km/s, we find that the orientation of IMF (clock angle) controls the speeds, while the magnitude of the solar wind electric field plays a minor role. The increasing speed indicates that energy transfer per unit length of the nightside X line increases as IMF turns southward.

  7. 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.

  8. Cyclotron resonance absorption in ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Villalon, Elena

    1991-04-01

    The mode conversion of ordinary polarized electromagnetic waves into electrostatic cyclotron waves in the inhomogeneous ionospheric plasma is investigated. Near resonance the warm plasma dispersion relation is a function of the angle theta between the geomagnetic field and the density gradient and of the wave frequency omega, which lies between the electron cyclotron frequency and its doubling. The differential equations describing the electric field amplitudes near the plasma resonance are studied, including damping at the second gyroharmonic. The energy transmission coefficients and power absorbed by the cyclotron waves are calculated. The vertical penetration of the plasma wave amplitudes is estimated using a WKB analysis of the wave equation.

  9. 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.

  10. 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 possible for the first time by the new transmitter capabilities, large bandwidth and especially the high ERP that allows for the first time operation at power density levels that exceed the theoretically predicted thresholds.

  11. The magnetosphere ionosphere system from the perspective of plasma circulation: A tutorial

    NASA Astrophysics Data System (ADS)

    Lotko, W.

    2007-03-01

    This tutorial review examines the role of O+ in the dynamics of magnetosphere ionosphere coupling. The life cycle of an O+ plasma element is considered as it circulates from the mid- to high-latitude ionosphere. Energization and diversion of the convecting plasma element into outflows involves Alfvénic turbulence at the low-altitude base of the cusp and plasmasheet boundary layer and in downward-current “pressure cookers.” Observational evidence indicating that O+ dominates the plasmasheet and ring current during extreme storm intervals is reviewed. The impacts of an O+-enriched plasma on solar wind magnetosphere ionosphere coupling are considered at both the micro and global scales. A synthesis of results from observation, theory and simulations suggests that the presence of O+ in the magnetosphere is both a disruptive and a moderating agent in maintaining the balance between dayside and nightside magnetic merging.

  12. Plasma waves in the inhomogeneous auroral ionosphere

    NASA Astrophysics Data System (ADS)

    Kintner, Paul

    1999-11-01

    Detailed observations of plasma waves in the auroral ionosphere during the past decade have revealed the existence of modes which depend on inhomogeneities the order of or somewhat larger than the ion gyroradius. The auroral ionosphere is the most strongly driven region of space which is conveniently accessible to space probes. The region is filled with currents, electric fields, electron beams and transversely accelerated ions. During the past decade improved instrumentation has permitted investigation of the ionospheric plasma properties down to spatial scales including the ion gyroradius. These investigations have revealed at least two novel wave modes not previously anticipated. The first wave mode is associated with cylindrical density cavities aligned along the geomagnetic field. The cavities act like resonant structures near the lower hybrid frequency and admit two classes of waves near the lower hybrid frequency. Below the lower hybrid frequency the modes are trapped and rotate in a left-hand sense. Above the lower hybrid frequency waves the modes are not trapped but rotate in a right-hand sense. The symmetry in rotation is broken by the Hall current and the sense of rotation has been confirmed with sounding rocket interferometers. The cavity wave fields also accelerate ions transversely which maintain and expand the cavity dimensions. The second wave mode is less well understood and has the phenomenological name of broad band ELF (BBELF) electric fields. The bandwidth of this mode covers the ion cyclotron frequencies (O+ and H+) and it is also associated with transversely accelerated ions but not with ionospheric density structuring. Instead these modes are associated with electron flow in field-aligned currents although the flows are sub-critical for either the ion acoustic or electrostatic ion cyclotron modes. Furthermore the frequency spectrum shows no structure at the ion cyclotron frequencies. Limited evidence suggests that these modes are shear assisted ion-acoustic or electrostatic ion-cyclotron modes. The shear may be either in the perpendicular flow or the parallel plasma flow. Thus far only shear in the perpendicular flow has been observed. Measuring parallel plasma flow shear presents an experimental challenge which has not yet been addressed.

  13. 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 et al. [Abdu, M.A., Sobral, J.H.A., Batista, I.S. Equatorial spread-F statistics in the american longitudes: some problems relevant to ESF description in the IRI scheme. Adv. Space Res. 25, 113-124, 2000.] from ground-based ionograms obtained over Brazilian region for the same years. The comparison shows good enough correlation ( R 0.67). It is concluded that: (a) He + density subtroughs like ESF are controlled by pre-reversal enhancement electric field (vertical drift); (b) He + density subtroughs and ESF/bubble irregularities may be considered as phenomena of the same plasma bubble origin; (c) it seems, plasma bubbles, reaching the topside ionosphere altitudes, are most easily observable in He + density as depletions.

  14. 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.

  15. A statistical study of the ionospheric convection response to changing interplanetary magnetic field conditions using the assimilative mapping of ionospheric electrodynamics technique

    NASA Astrophysics Data System (ADS)

    Ridley, A. J.; Lu, Gang; Clauer, C. R.; Papitashvili, V. O.

    1998-03-01

    We examine 65 ionospheric convection changes associated with changes in the Y and Z components of the interplanetary magnetic field (IMF). We measure the IMF reorientations (for all but six of the events) at the Wind satellite. For 22 of the events the IMF reorientation is clearly observed by both Wind and IMP 8. Various methods are used to estimate the propagation time of the IMF between the two satellites. We find that using the magnetic field before the IMF orientation change gives the smallest error in the expected propagation time. The IMF is then propagated to the magnetopause. The communication time between when the IMF encounters the magnetopause and the start of the convection change is estimated to be 8.4(+/-8.2)min. The resulting change in the ionospheric potential is examined by subtracting a base potential pattern from the changing potential patterns. From these residual patterns, a number of conclusions are made: (1) the location of the change in convection is stationary, implying that the change in convection is broadcast from the cusp region to the rest of the ionosphere in a matter of seconds and that the electric field mapped down the cusp controls the entire dayside ionospheric convection pattern; (2) the shape of the change in the ionospheric convection is dependent on the IMF component that changes, which is indicative of the change in the merging rate on the dayside magnetopause; (3) 62% of the events change linearly form one state to another, while 11% of the events change asymptotically; (4) the change in the ionospheric potential is linearly related to the magnitude of the IMF orientation, with Bz changes having a larger proportionality constant than By changes; (5) the ionospheric convection takes, on average, 13 min to completely reconfigure; and (6) some of the ionospheric convection changes occur on a timescale shorter than that of the corresponding IMF reorientation, possibly as a result of thresholding in the dayside merging region.

  16. 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.

  17. Rocket and satellite observations of electric fields and ion convection in the dayside auroral ionosphere

    NASA Technical Reports Server (NTRS)

    Marklund, G. T.; Heelis, R. A.; Winningham, J. D.

    1986-01-01

    The electric field and convection pattern of the dayside auroral ionosphere are analyzed using electric-field data from two high-altitude rocket flights in the polar cusp and satelltie observations of ion drifts and energetic particles. The geophysical conditions for December 1 and 13, 1981 are described. The flow reversals for the two events are studied, and a dayside convection pattern is characterized. It is observed that this convection pattern is in qualitative agreement with the predictions of a geometrical model of Crooker (1979), when the IMF is oriented towards dawn.

  18. Plasma Pressure in the Topside Ionosphere

    NASA Technical Reports Server (NTRS)

    Newell, Patrick T.

    1999-01-01

    A previous three year NASA-funded project resulted in the first 2-D maps of magnetotail pressure, density and temperature. A proposal to continue the work was declined, but modest funding was provided for one year to ramp down of the work. During the phase-out year, we used a time when 5 DMSP satellites were simultaneously active to produce the first instantaneous partial image of the magnetotail. The results have been submitted to the proceedings of the 1998 Huntsville Meeting on "The New Millennium Magnetosphere: Integrating Imaging, Discrete Observations and Global Simulations". A method of inferring central plasma sheet (CPS) temperature, density, and pressure from ionospheric observations was developed under a previous 3-year grant. These particles properties are calculated from data taken by particle instruments on DMSP satellites. Ion spectra occurring in conjunction with electron acceleration events are excluded. Because of the variability of magnetotail stretching, mapping to the plasma sheet was done using a modified Tsyganenko 1989 magnetic field model adjusted to agree with the actual magnetotail stretch. On May 25, 1997, five DMSP satellites (F10-F14) passed through the southern hemisphere nightside oval within a 19 minute period. Attached is the first magnetotail image, which results from applying our technique to that data set.

  19. Global MHD modeling of ionospheric convection and field-aligned currents associated with IMF By triggered theta auroras

    NASA Astrophysics Data System (ADS)

    Watanabe, Masakazu; Sakito, Shintaro; Tanaka, Takashi; Shinagawa, Hiroyuki; Murata, Ken T.

    2014-08-01

    Using numerical magnetohydrodynamic simulations, we investigate the evolution of ionospheric convection and field-aligned currents (FACs) when θ auroras are formed in response to interplanetary magnetic field (IMF) By transitions. When the polarity of IMF By switches abruptly during northward IMF periods, the crossbar of the θ aurora is isolated from the flankside auroral oval and drifts into the polar cap. This drift motion is involved in a large round cell associated with new IMF By, with sunward convection residing only on the dayside tip of the crossbar. There exists an IMF By-controlled large-scale FAC system on the crossbar. When the θ aurora is drifting duskward (dawnward), the FACs are located on the dawnside (duskside) boundary of the crossbar adjacent to the "new" lobe. In contrast, the magnetospheric source region of the crossbar FAC system is located on the duskside (dawnside) boundary of the protruded plasma sheet adjacent to the "old" lobe. In the source region, plasma thermal pressure feeds the electromagnetic energy of FACs, and these processes can be interpreted as coupling of slow mode and Alfvén mode disturbances. In the ionosphere, the crossbar-associated FACs close with part of the region 1 currents associated with the new crescent cell. The magnetospheric source of that part of the region 1 FACs is located on the plasma sheet boundary and the magnetopause both adjacent to the new lobe. Dynamo processes in the old-lobe side and the new-lobe side work together to drive the ionospheric drift motion of the crossbar.

  20. 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.

  1. Investigating the Importance of Viscous Interactions on Ionospheric Convection via Comparisons of Open-Closed Boundaries (OCBs) and Convection Reversal Boundaries (CRBs)

    NASA Astrophysics Data System (ADS)

    Hutchinson, J. A.; Wright, D. M.; Milan, S. E.; Grocott, A.; Boakes, P. D.

    2012-04-01

    Geomagnetic storms cause large global disturbances in the Earth's magnetosphere, during which large amounts of energy are deposited in the magnetotail and inner magnetosphere, producing an enhanced ring current and energising plasma to relativistic levels by poorly-understood excitation mechanisms. A previous study by Hutchinson et al. [2011] identified 143 geomagnetic storms over the last solar cycle (1997-2008) from the global SYM-H index and associated solar wind (SW) data from the Advanced Composition Explorer (ACE) spacecraft. Current work continues to use this dataset to investigate the characteristic ionospheric convection during magnetic storms via radar backscatter observed by the Super Dual Auroral Radar Network (SuperDARN). A superposed epoch analysis is completed using the map potential technique of Ruohoniemi and Baker [1998]. This technique has previously successfully been used to investigate substorm convection, however the technique has not particularly been employed for studies of geomagnetic storms nor has the model fit been applied to combined radar data from multiple storms for statistical studies rather than performing the analysis on an individual storm by storm basis. Latitude-Time-Velocity (LTV) plots, analogous to standard Range-Time-Intensity (RTI) plots, are used to visualise the results, which show the 'average' ionospheric response during different sized geomagnetic storms as the substorm control on the convection is mostly 'averaged out'. This, along with the cross-cap potential derived from the superposed SuperDARN results, is compared with similarly superposed auroral images from the IMAGE and POLAR spacecraft missions to better constrain the storm time coupling between the solar wind and magnetosphere. Results from the comparison of the convection reversal boundaries (derived from the SuperDARN data) and open-closed boundaries (from the auroral imagery) are presented to investigate the significance of a possible viscous interaction between the solar wind and the magnetosphere in addition to the normal reconnection-driven interaction.

  2. 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.

  3. Multi-Resolution Assimilative Analysis of High-Latitude Ionospheric Convection in both Hemispheres

    NASA Astrophysics Data System (ADS)

    Thomas, Z. M.; Matsuo, T.; Nychka, D. W.; Cousins, E. D. P.; Wiltberger, M. J.

    2014-12-01

    Assimilative techniques for obtaining complete maps of ionospheric electric potential (and related parameters) from sparse radar and satellite observations greatly facilitates studies of magnetosphere/ionosphere coupling. While there is much scientific interest in studying interhemispheric asymmetry in ionospheric convection at both large and small scales, current mapping procedures rely on spherical harmonic expansion techniques, which produce inherently large-scale analyses. Due to the global nature of the spherical harmonics, such techniques are also subject to various instabilities arising from sparsity/error in the observations which can introduce non-physical patterns in the inferred convection. We present a novel technique for spatial mapping of ionospheric electric potential via a multi-resolution basis function expansion procedure, making use of compactly supported radial basis functions which are flexibly located over geodesic grids; the coefficients are modeled via a Markov random field construction. The technique is applied to radar observations from the Super Dual Auroral Radar Network (SuperDARN), whereupon careful comparison of interhemispheric differences in mapped potential is made at various scales.

  4. 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.

  5. 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.

  6. 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.

  7. Anomalous ionospheric conductivities caused by plasma turbulence in high-latitude E-region ionosphere

    NASA Astrophysics Data System (ADS)

    Dimant, Yakov; Oppenheim, Meers

    2015-11-01

    During periods of intense geomagnetic activity, electric fields penetrating from the Earth's magnetosphere to the high-latitude E-region ionosphere drive strong currents named electrojets and excite there plasma instabilities. These instabilities give rise to plasma turbulence that induces nonlinear currents and strong anomalous electron heating. This increases the ionospheric conductances and modifies the global energy flow, affecting behavior of the entire near-Earth plasma. A quantitative understanding of anomalous conductance and global energy transfer is important for accurate modeling of the geomagnetic storm/substorm evolution. Our theoretical analysis, supported by recent 3D fully kinetic particle-in-cell simulations, shows that during strong geomagnetic storms the inclusion of anomalous conductivity can more than double the total Pedersen conductance - the crucial factor responsible for magnetosphere-ionosphere coupling through the current closure. We have started incorporating the effects of anomalous heating and nonlinear conductivity into existing global magnetosphere-ionosphere-thermosphere codes developed for predictive modeling of Space. In our presentation, we will report on the latest progress in this modeling. Work supported by NASA Heliophysics GCR Grant NNX14AI13G.

  8. Interplanetary magnetic field By and auroral conductance effects on high-latitude ionospheric convection patterns

    NASA Astrophysics Data System (ADS)

    Tanaka, T.

    2001-11-01

    The dependence of the ionospheric electric potential (convection) on the interplanetary magnetic field (IMF) and the ionospheric conductivity is investigated to understand the generation of convection patterns in the framework of the solar wind-magnetosphere-ionosphere (S-M-I) coupling scheme and the merging concept. A numerical magnetohydrodynamic (MHD) simulation is adopted for the study of the present problem. To achieve a high resolution in the ionosphere, the MHD calculation employs the finite volume (FV) total-variation diminishing (TVD) scheme with an unstructured grid system. The two-cell convection patterns reproduced from simulation are shown for several cases under the southward IMF condition during the growth-phase interval. In the investigation of these results, special attention is paid to the analysis of mirror symmetry in the convection patterns with respect to the IMF By. On the dayside in the Northern Hemisphere, IMF By- (By+) generates flow deflection on newly opened field lines toward the dusk (dawn) without a severe violation of the mirror symmetry. While the mirror symmetry of the convection pattern is maintained even on the nightside when the ionospheric conductivity is uniform, it is not maintained on the nightside when the ionospheric conductivity is nonuniform. A realistic ionospheric conductivity modifies the convection pattern in the Northern (Southern) Hemisphere so as to emphasize distinctive features seen for IMF By+ (By-) under a uniform conductivity, and the reproduced convection patterns coincide with the observation quite well including fine signatures on the nightside, both for IMF By- and By+. Because of the nonuniform conductivity, cell centers of convection are shifted to the earlier magnetic local times, and the antisunward flow in the northern polar cap is nearly aligned with noon-midnight meridian for IMF By-, while the flow in the northern polar cap has a significant inclination from prenoon to premidnight for IMF By+. These convection patterns can be understood by considering the effect due to the Hall current closure of the region-1 field-aligned current. The analysis for the dependence of nightside convection on IMF By and ionospheric conductivity shows that the Harang discontinuity is attributed partially to the structure of magnetospheric driver but mainly to the effect of nonuniform auroral conductivity. As a consequence, it is more adequate to say that convection patterns are more or less caused by the synthesized effect of more than one process rather than a single elementary process. Reproduced convection patterns in this paper show a particular coincidence with satellite observations summarized by adopting the pattern-recognition-based approach.

  9. Coupled Magnetotail-Ionosphere Asymmetries from Ionospheric Hall Conduction

    NASA Astrophysics Data System (ADS)

    Lotko, W.; Smith, R. H.; Zhang, B.; Ouellette, J.; Brambles, O.; Lyon, J.; Wiltberger, M. J.

    2014-12-01

    Fast convective transport in the plasma sheet is more prevalent in the premidnight (dusk) sector relative to postmidnight. Ionospheric convection exhibits related asymmetries - more flux typically circulates in the dusk cell than in the dawn cell, and the nightside convection pattern is rotated clockwise when viewed over the North Pole. We show, using global simulations of the solar wind-magnetosphere-ionosphere interaction, that the electrodynamic interaction between Earth's magnetosphere and ionosphere produces asymmetries resembling observed distributions in plasmasheet flows and ionospheric convection (Figure, center panel). The primary causal agent in the simulations is a meridional gradient in ionospheric Hall conductance which, through Cowling polarization, regulates the distributions of i) electrical currents flowing within and between the ionosphere and magnetotail and ii) the nightside reconnection rate and resulting dawn-dusk distribution of plasma sheet fast flows. The asymmetry disappears in the simulation when the Hall conductance is taken to be uniform (left panel), and it reverses when the conductance is artificially depleted at auroral latitudes (right panel). The coupling between meridional currents and electric fields in the ionosphere and axial currents and electric fields in the plasmasheet is demonstrated by a simple model for non-ideal coupling of field-aligned currents flowing between the plasma sheet and the region of enhanced ionospheric conductance straddling the nightside convection throat.

  10. 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%.

  11. How Solar Wind-Magnetosphere-Ionosphere Coupling Differentiates Magnetospheric Convection Modes

    NASA Astrophysics Data System (ADS)

    Lotko, W.; Brambles, O.; Ouellette, J.; Zhang, B.; Lyon, J.; Wiltberger, M. J.; Merkin, V. G.

    2012-12-01

    Magnetosphere-ionosphere (MI) coupling is mediated by fluxes of charged-particles and electromagnetic energy flowing between the magnetosphere and ionosphere. Synchronous MI coupling occurs when these fluxes rapidly transit between the two regions relative to the time scale for substorm-induced changes in convection. Latent MI coupling occurs when fluxes stimulated by dynamical changes in one region (e.g., ionospheric outflows) are slow to reach and affect the other region (e.g., the plasmasheet). With continual strong solar wind / interplanetary magnetic field (SW/IMF) driving, latent coupling has the capacity to produce relaxation oscillations of the coupled system. Fast flux exchanges are mediated by electrons and Alfvén waves; slow exchanges are mediated by ion flows, principally O+. With this background, the following scenario for the role of MI coupling in producing different magnetospheric convection modes is considered, with the concepts illustrated by global simulations. The steady magnetospheric convection (SMC) mode occurs for the SW/IMF driving conditions reported in statistical studies, e.g. DeJong et al. (2009). Global simulations indicate that the mean conditions inducing SMC do not stimulate sufficient low-altitude activity to sustain the intense ionospheric outflows that produce large changes in the nightside plasmasheet and reconnection rate. For the SMC mode, MI coupling is thus mediated mainly by flows of electrons and Poynting fluxes between the two regions. Substorms (and more strongly driven proto-SMC events) deposit substantial electromagnetic and particle energy in the ionosphere and low-altitude magnetosphere. If the energy deposition is sufficient to power intense fluxes of heavy ion outflows, the pressure of the outflowing-come-plasmasheet ions will eventually inflate and stretch the nightside plasmasheet and modify the nightside reconnection rate. Several modes of response are then possible depending on the persistence of SW/IMF driving. The causative substorm is "isolated" if the SW/IMF driving that produced it is not subsequently maintained, i.e., the driving fails to increase the magnetic flux in the polar cap. This class includes impulsively triggered substorms, some of which might otherwise continue as an SMC state. Whether the isolated substorm is preceded and/or followed by an SMC state or irregular activity depends on the variability of SW/IMF driving. A quasi-periodic sequence of substorms follows the initiating substorm when energy transfer to the magnetosphere by strong, persistent and quasi-steady SW/IMF driving maintains a superfluent outflow flux from the nightside ionosphere, while continuing to add lobe magnetic flux. These distinctions are illustrated by global simulations of interplanetary SI and CME events, together with numerical experiments based on controlled SW/IMF conditions.

  12. On the Generation of Enhanced Sunward Convection and Transpolar Aurora in the High-Latitude Ionosphere by Magnetic Merging

    NASA Astrophysics Data System (ADS)

    Eriksson, S.; Baker, J. B.; Petrinec, S. M.; Elkington, S. R.; Dunlop, M. W.; Reme, H.; Greenwald, R. A.; Frey, H. U.; Ergun, R. E.; Balogh, A.

    2004-12-01

    The IMAGE SI-12 instrument indicates a region of diffuse aurora poleward of the duskside Northern Hemisphere oval, while the IMAGE WIC instrument observes a transpolar auroral (TPA) feature at the polar cap boundary of the diffuse aurora during much of the 0110 UT to 0445 UT time interval on 16 December 2001. We here focus on the 0302 UT to 0312 UT period when the SuperDARN convection data display enhanced 800-1100 m/s sunward directed ionospheric flows near the TPA region in a four-degree wide region centered at 81o magnetic latitude between 14 MLT and 16 MLT. This flow channel seemingly drives a single dayside lobe cell with a convection reversal boundary near 84o and 14 MLT. At 0300 UT, the Cluster C1 S/C traverses the Northern Hemisphere duskside flank magnetopause at [X,Y,Z]=[-1.2,9.2,9.1] RE (GSM) where it encounters a localized density depletion region and a clear deflection of the bulk plasma velocity relative to the observed magnetosheath flow. The magnetic field and plasma velocity observed by C1 satisfy the Walen stress balance relation for a rotational discontinuity and the corresponding flow deflection dV suggests a merging site poleward and tailward of the spacecraft. The IMF magnitude as measured by ACE is 18 nT with a steady and favorable 45o clock angle (positive By and Bz) direction for merging in the vicinity of these duskside regions. The Tsyganenko T01 model maps the Cluster position to 75o and 14 MLT at 0130 UT or a few degrees equatorward of the ionospheric flow channel. Based on these data sets, we examine whether the active merging region on the magnetopause is consistent with the enhanced flow signatures observed by SuperDARN on 16 December 2001 and the IMAGE observations in these duskside high-latitude regions. An MHD simulation of this event puts these observations into a global context and is further used to map the Cluster location at the time of the plasma flow deflections to the ionosphere.

  13. 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.

  14. Interplanetary magnetic field control of the ionospheric field-aligned current and convection distributions

    NASA Astrophysics Data System (ADS)

    Juusola, L.; Milan, S. E.; Lester, M.; Grocott, A.; Imber, S. M.

    2014-04-01

    Patterns of the high-latitude ionospheric convection and field-aligned current (FAC) are a manifestation of the solar wind-magnetosphere-ionosphere coupling. By observing them we can acquire information on magnetopause reconnection, a process through which solar wind energy enters the magnetosphere. We use over 10 years of magnetic field and convection data from the CHAMP satellite and Super Dual Auroral Radar Network radars, respectively, to display combined distributions of the FACs and convection for different interplanetary magnetic field (IMF) orientations and amplitudes. During southward IMF, convection follows the established two-cell pattern with associated Region 1 and Region 2 FACs, indicating subsolar reconnection. During northward IMF, superposed on a weak two-cell pattern there is a reversed two-cell pattern with associated Region 0 and Region 1 FACs on the dayside, indicating lobe reconnection. For dominant IMF Bx, the sign of Bz determines whether lobe or subsolar reconnection signatures will be observed, but Bx will weaken the signatures compared to pure northward or southward IMF. When the IMF rotates from northward to duskward or dawnward, the distinct reversed and forward two-cell patterns start to merge into a distorted two-cell pattern. This is in agreement with the IMF By displacing the reconnection location from the open lobe field lines to closed dawn or dusk field lines, even though IMF Bz>0. As the IMF continues to rotate southward, the distorted pattern transforms smoothly to that of the symmetric two-cell pattern. While the IMF direction determines the configuration of the FACs and convection, the IMF amplitude affects their intensity.

  15. 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), depending on magnetic activity, the dawn sector has slightly higher pressure. The temperature and density asymmetries in the near-Earth region are consistent with the ion westward gradient/curvature drift as the ions ExB convect earthward. When the solar wind dynamic pressure increases, CPS density and pressure appear to increase, but the temperature remains relatively constant. Comparison with previously published work indicates good agreement between the inferred pressure, temperature, and density and those obtained from in situ data. This new method should provide a continuous mechanism to monitor the pressure, temperature, and density in the magnetotail with unprecedented comprehensiveness.

  16. 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.

  17. 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.

  18. 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

  19. Localized lower hybrid acceleration of ionospheric plasma

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Vago, J.; Chesney, S.; Arnoldy, R. L.; Lynch, K. A.; Pollock, C. J.; Moore, T. E.

    1992-01-01

    Observations of the transverse acceleration of ions in localized regions of intense lower hybrid waves at altitudes near 1000 km in the auroral ionosphere are reported. The acceleration regions are thin filaments with dimensions across geomagnetic field lines of about 50-100 m corresponding to 5-10 thermal ion gyroradii or one hot ion gyroradius. Within the acceleration region lower hybrid waves reach peak-to-peak amplitudes of 100-300 mV/m and ions are accelerated transversely with characteristic energies of the order of 10 eV. These observations are consistent with theories of lower hybrid wave collapse.

  20. Impact of the dipole tilt angle on the ionospheric plasma in the outer plasmasphere

    NASA Astrophysics Data System (ADS)

    Marchaudon, Aurelie; Blelly, Pierre-Louis

    2015-04-01

    We have developed a new interhemispheric 16-moment based ionosphere model. This model describes the field-aligned transport of the multi-species ionospheric plasma (6 ions) from one hemisphere to the other, taking into account source processes at low altitudes (photoionization, chemistry) and coupling with suprathermal electrons. We simulate the convection and corotation transport of closed flux tubes in the outer plasmasphere for tilted/eccentric dipolar magnetic field configuration. We ran the model in solstice and equinox conditions and for two plasmapause boundary conditions: one corresponding to standard conditions with a stagnation point at 4.5 Earth radii (RE) and 15h Magnetic Local Time (MLT) and one corresponding to very quiet conditions with a stagnation point at 6 RE and 15h MLT. For each season/stagnation simulation, the model is run for 30 days before the equinox/solstice date in order to eliminate the transients. The goal is to study the combined effect of the tilt of the magnetic field and the rotation axis on the field-aligned dynamics and overall equilibrium of the subauroral ionosphere. In the classical representation of the plasmasphere, the ionosphere only depends on angular MLT sector. We will show that due to the tilt effect, this view is erroneous and no real dynamic equilibrium is reached, in particular close to the stagnation point where we can observe large day-to-day variations in the ionospheric parameters. Finally, we will present the temperatures anisotropy development along the flux tube for different positions of the stagnation point.

  1. Plasma motion in the Venus ionosphere: Transition to supersonic flow

    SciTech Connect

    Whitten, R.C.; Barnes, A. ); McCormick, P.T. )

    1991-07-01

    A remarkable feature of the ionosphere of Venus is the presence of nightward supersonic flows at high altitude near the terminator. In general the steady flow of an ideal gas admits a subsonic-supersonic transition only in the presence of special conditions, such as a convergence of the flow followed by divergence, or external forces. In this paper, the authors show that the relatively high pressure dayside plasma wells up slowly, and at high altitude it is accelerated horizontally through a relatively constricted region near the terminator toward the low-density nightside. In effect, the plasma flows through a nozzle that is first converging, then diverging, permitting the transition to supersonic flow. Analysis of results from previously published models of the plasma flow in the upper ionosphere of Venus shows how such a nozzle is formed. The model plasma does indeed accelerate to supersonic speeds, reaching sonic speed just behind the terminator. The computed speeds prove to be close to those observed by the Pioneer Venus orbiter, and the ion transport rates are sufficient to produce and maintain the nightside ionosphere.

  2. Twin-vortex Convection in the Nightside High-Latitude Ionosphere Observed by the New Polar Cap SuperDARN Radar at Rankin Inlet

    NASA Astrophysics Data System (ADS)

    McWilliams, K. A.

    2006-12-01

    The opening and closing of magnetic flux by reconnection at the dayside magnetopause and in the magnetotail is the primary driver of convection in the magnetosphere and polar ionospheres. It is not the existence of open flux that excites convection; rather it is the creation or destruction of open flux that excites convection. These flows persist until a new equilibrium condition is reached, assuming no further reconnection occurs. The time scale for the excitation and decay of ionospheric flows depends on the time necessary for the polar cap to reconfigure following reconnection. The consequence of this zero-flow equilibrium concept (Cowley and Lockwood, 1992) has a powerful consequence when considering both bursty and steady-state reconnection. Newly created regions of open flux are appended contiguously to the polar cap adjacent to the previously reconnected region of open flux. Similarly, newly closed flux regions are appended contiguously to the closed field line region outside the polar cap on the nightside. The opening or closing of magnetic flux will create a perturbation of the polar cap boundary, and convection cells develop at the ends of the reconnection X-line. Convection is excited such that the newly created open flux is incorporated into the polar cap on the dayside or the newly closed flux is excluded from the polar cap on the nightside. The observation of the nightside convection response to reconnection has been very difficult to accomplish because (a) the nightside has a far more dynamic and complex response to reconnection, and (b) radar observations of convection in the midnight sector are difficult to achieve due to absorption of the radio waves during active conditions. The newest SuperDARN radar at Rankin Inlet is located at very high latitudes (73.2 magnetic), and it offers extensive and nearly continual observations of plasma convection in the poleward part of the nightside auroral region. Because of its high latitude, the Rankin Inlet radar effectively does not experience signal absorption, compared with the auroral SuperDARN radars. The Rankin Inlet radar often detects plasma convection into the polar cap on the nightside, as expected for the reconnection-induced convection vortices. Similar flows are only very rarely seen by the auroral SuperDARN radars, and this requires extremely disturbed conditions when the polar cap is extremely large and equatorward of the SuperDARN auroral radars. Examples of the nightside reconnection response observed by the Rankin Inlet radar and the auroral SuperDARN radars will be presented.

  3. Response time of the polar ionospheric convection pattern to changes in the north-south direction of the IMF

    SciTech Connect

    Hairston, M.R.; Heelis, R.A.

    1995-03-01

    A three-day period from January 27 through January 29, 1992 is analyzed using one minute resolution solar wind data from the IMP-8 satellite and the ionospheric convection pattern data derived from the four operational DMSP satellites. During this period there were several clear reversals of the sign of the z component of the interplanetary magnetic field (IMF) which is known to have a direct effect on the convection patterns observed in the polar ionosphere. Polar convection patterns observed by the frequent passes of four DMSP satellites are examined following each sign change to determine the time lag between the change in the IMF at the magnetopause and the establishment of a new global convection signature in the ionosphere. After removing the transit time for the IMF to travel from the position of the IMP-8 satellite to the magnetopause, a further time lag of about 17 to 25 minutes is observed for the five cases where the IMF turned from northward to southward. A longer lag of between 28 and 44 minutes is observed for the two cases where the IMF turned from southward to northward. These lags are interpreted as the inertial response time of the ionosphere in reacting to the change in the IMF. 16 refs., 4 figs.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. A Miniature Sweeping Impedance Probe for Ionospheric Plasma Diagnostics

    NASA Astrophysics Data System (ADS)

    Martin-Hidalgo, J.; Swenson, C.

    2013-12-01

    The impedance of a probe immersed in ionospheric plasma at radio frequencies is an important technique for determining absolute electron density. Building on 50 years of history in developing and flying RF probes for plasma diagnostics at Utah State, a new SIP (Sweeping Impedance Probe) design has been completed which will obtain qualitative improvement over previous instruments in terms of accuracy and sweep rate. This instrument will provide a continuous measurement of the plasma impedance magnitude and phase with an expected accuracy of 1% and 1 degree respectively over the 1 to 20 MHz range. This new SIP will be launched in January 2014 onboard the Auroral Spatial Structures Probe (ASSP) NASA sounding rocket mission using a short monopole probe. The rocket apogee of 600 km will allow the characterization of the plasma in the E and F layers at auroral latitudes and the study of short term and spatial variations along the high-altitude profile of the sounding rocket. Although this SIP design has been developed for a sounding rocket, it can be optimized and miniaturized for Cubesat's and included along other ionospheric diagnostic instruments such as double and Langmuir probes. This presentation is focused on the overall design of the instrument, the tests results for the ASSP instrument and conceptual designs for future CubeSat mission similar to the NSF DICE mission.

  12. 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.

  13. 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.

  14. Plasma bubbles in the topside ionosphere: solar activity dependence

    NASA Astrophysics Data System (ADS)

    Sidorova, L.

    2009-04-01

    The present study deals with the He+ density depletions, observed during a high solar activity at the topside ionosphere heights. There are the indications that plasma bubbles, produced by Rayleigh-Taylor instability at the bottomside of ionosphere, could rise up to the topside ionosphere and plasmasphere. Maryama and Matuura (1984), using ISS-b spacecraft data (high solar activity - F10.7=200, 1978-80), have seen the plasma bubbles in Ne density over equator at 1100 km heights in 46 cases in 1700 passes (3%). However, there is distinctly another picture in He+ density depletions according to ISS-b spacecraft data for the same period. They occur in the topside ionosphere over low- and middle- latitudinal regions (L=1.3-3) in 11% of the cases (Karpachev, Sidorova, 2002; Sidorova, 2004, 2007). The detailed study of the He+ density depletion characteristics was done. It was noted that the He+ density depletions are mostly seen in the evening-night sector (18-05 LT) from October till May. It was like to the peculiarities of the Equatorial Spread-F (ESF), usually associated with plasma bubble. The monthly mean He+ density depletion statistics, plotted in LT versus month, was compared with the similar plots for ESF statistics, obtained by Abdu and colleagues (2000) from ground-based ionograms over Brazilian regions for the period of the same solar activity. It was revealed good enough correlation (R=0.67). Also depletion values as function of LT were compared with the vertical plasma drift velocity variations, obtained for the same period from AE-E spacecraft and IS radar (Jicamarca) data. Striking similarity in development dynamics was revealed for the different seasons. It was concluded, that the He+ density depletions should be considered as originating from equatorial plasma bubbles. It seems the plasma bubbles, reaching the topside ionosphere altitudes, are mostly seen not in electron density but in He+ density as depletions. According to publications, many cases of the He+ density depletions were revealed on OGO-4, OGO-6, Oreol-1 and DE-2 spacecraft data. The most of these cases occur during high and maximal solar activity periods, when the He+ density layer is very well developed at the topside ionosphere heights (Wilford et al., 2003). Using the model of the plasma bubble formation as suggested by Woodman and La Hoz (1976), it was shown that the topside plasma bubbles, seen in He+ density, are rather typical phenomena for the topside ionosphere for high solar activity epoch. REFERENCE Abdu, M.A., J.H.A. Sobral, I.S. Batista, Equatorial spread F statistics in the american longitudes: some problems relevant to ESF description in the IRI scheme, Adv. Space Res., vol. 25, pp. 113-124, 2000. Karpachev, A.T. and L.N. Sidorova, Occurrence probability of the light ion trough and subtrough in ??+ density on season and local time, Adv. Space Res., vol. 29, pp. 999-1008, 2002. Maryama, T. and N. Matuura, Longitudinal variability of annual changes in activity of equatorial spread F and plasma bubbles, J. Geophys. Res., 89(A12), 10,903-10,912, 1984. Sidorova, L.N., He+ density topside modeling based on ISS-b satellite data, Adv. Space Res., vol. 33, pp. 850-854, 2004. Sidorova, L.N., Plasma bubble phenomenon in the topside ionosphere, Adv. Space Res., Special issue (COSPAR), doi: 10.1016/j.asr.2007.03.067, 2007. Wilford, C.R., R.J. Moffett, J.M. Rees, G.J. Bailey, Comparison of the He+ layer observed over Arecibo during solar maximum and solar minimum with CTIP model results, J. Geophys. Res., vol. 108, A12, pp. 1452, doi:10.1029/2003JA009940, 2003. Woodman, R.F. and C. La Hoz, Radar observations of F-region equatorial irregularities, J. Geophys. Res., vol. 81, pp. 5447-5466, 1976.

  15. Ionospheric chemical releases

    NASA Technical Reports Server (NTRS)

    Bernhardt, Paul A.; Scales, W. A.

    1990-01-01

    Ionospheric plasma density irregularities can be produced by chemical releases into the upper atmosphere. F-region plasma modification occurs by: (1) chemically enhancing the electron number density; (2) chemically reducing the electron population; or (3) physically convecting the plasma from one region to another. The three processes (production, loss, and transport) determine the effectiveness of ionospheric chemical releases in subtle and surprising ways. Initially, a chemical release produces a localized change in plasma density. Subsequent processes, however, can lead to enhanced transport in chemically modified regions. Ionospheric modifications by chemical releases excites artificial enhancements in airglow intensities by exothermic chemical reactions between the newly created plasma species. Numerical models were developed to describe the creation and evolution of large scale density irregularities and airglow clouds generated by artificial means. Experimental data compares favorably with theses models. It was found that chemical releases produce transient, large amplitude perturbations in electron density which can evolve into fine scale irregularities via nonlinear transport properties.

  16. 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.

  17. Optical remote sensing of the ion convection pattern in the high-latitude ionosphere from a polar orbiting satellite

    SciTech Connect

    Minow, J.I.; Smith, R.W. )

    1993-04-09

    Presented is a technique where on a routine basis a single satellite borne instrument can be used to determine quasi-instantaneous ion convection patterns over the entire high-latitude ionosphere. The remote sensing technique utilizes the Doppler shift information in the optical emissions originating from thermospheric ions drifting in response to the Earth's magnetic and convection electric fields. The feasibility of the technique is demonstrated using a computer simulation. The simulation shows that a satellite can obtain information with sufficient spatial resolution to obtain quasi-instantaneous estimates of ion convection patterns. The results are accurate enough to distinguish between features present in currently accepted averaged models of ion convection. 20 refs., 3 figs.

  18. Electromagnetically Driven Plasma-Field Dynamics in Modified Ionosphere

    NASA Astrophysics Data System (ADS)

    Kochetov, Andrey; Terina, Galina

    Under sounding of an artificial ionospheric turbulence by short probing radio pulses of ordinary polarization the two types of scattered signals were observed: a "caviton" signal (CS) and a "plasma" signal (PS), which appeared with the heating transmitter switching on and disap-peared after its switching off (G.I. Terina J. Atm. Terr. Phys, 57, 1995, 273, Izv. VUZov, Radiofizika, 39, 1998, 203). The scattered signal of PS type was revealed also after the heating switching off. It was called an "aftereffect plasma signal" (AEPS) (G.I. Terina Izv .VUZov, Radiofizika, 43, 2000, 958). This signal had large time and spatial delays and appeared mostly when corresponding PS had envelope fluctuations. The aftereffect phenomenon was expressed at time on CS by amplitude increasing at once after the heating transmitter turning off. The theoretical model of this phenomenon is proposed in and some peculiarities of the aftereffect phenomena of the scattered signals in modified ionospheric plasma are considered and discussed. For theoretical interpretation of the characteristics of CS and AEPS the numerical solution of nonlinear Shrüdinger equation (NSE) with driven extension were carried out in inhomogeneous plasma layer with linear electron density profile (A.V. Kochetov, V.A. Mironov, G.I. Terina, Adv. Space Reseacrh, 29, 2002, 1369) and for the one with prescribed density depletion (and A.V. Kochetov, G.I. Terina, Adv. Space Reseacrh, 38, 2006, 2490). The simulation results obtained for linear inhomogeneous plasma layer and for plasma one with density depletion al-low us to interpret the aftereffect of CS and PS qualitatively. The field amplitude increase at relaxation stage displayed at calculations allows us to interpret of CS aftereffect. The large time delays of AEPS can be explained as a result of powerful radio waves trapping in the forming at the plasma resonance regions density depletions (E. Mjøhus, J. Geophys. Res. 103, 1998, 14711; B. Eliasson and L. Stenflo, J. Geophys. Res., 113, 2008, A02305). It should be noted that PS and CS are analogous to different components of the stimulated electromagnetic emis-sion (SEE): "broad continuum" (BC) and narrow continuum" (NC) accordingly (see, e.g. (B. Isham, C. La Hoz, M.T. Rietveld, T. Hagfors, T.B. Leyser, Phys. Rev. Lett., 83, 1999, 2576)). AEPS is corresponded to Diagnostic SEE at the relaxation stage. The work was supported in part by RFBR grant 09-02-01150-a.

  19. 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).

  20. 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.

  1. 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 trapped within the magnetosphere and how much is lost to the solar wind.

  2. Observation of Plasma Oscillating Structures in External Ionosphere over Cyclones

    NASA Astrophysics Data System (ADS)

    Belyaev, G.; Bankov, N.; , Boychev, B.; Kostin, V.; Trushkina, E.; Ovcharenko, O.

    2012-08-01

    The results of the observations of density, temperature, pressure of plasma, electrical fields and low-frequency fluctuations were obtained on both Cosmos-1809 and Intercosmos-Bulgaria-1300 satellites. The complex analysis of the results of observations showed the appearance of electrical fields and intensive low-frequency fluctuations, the reaction of electron density, temperature, pressure of plasma at the height of approximately 900 km above the regions of appearance and development of tropical and extra-tropical cyclones. The cases of simultaneous observations of several cyclones, which sharply changed their direction of motion are considered. At the same time over half of the cyclones identical plasma solutions were found. These structures have a core, where the oscillations of the density reach 10% and have a transverse scale of 10 km, and the periphery with smaller amplitudes and stretched density oscillations. These density holes filled with the electrostatic turbulence at the frequency of helium. The results obtained suggest that the different stages of development of tropical and extra-tropical cyclones and the formation of individual structural formations of the ionosphere are related dynamic processes

  3. On the generation of enhanced sunward convection and transpolar aurora in the high-latitude ionosphere by magnetic merging

    NASA Astrophysics Data System (ADS)

    Eriksson, S.; Baker, J. B. H.; Petrinec, S. M.; Wang, H.; Rich, F. J.; Kuznetsova, M.; Dunlop, M. W.; RMe, H.; Greenwald, R. A.; Frey, H. U.; Lhr, H.; Ergun, R. E.; Balogh, A.; Carlson, C. W.

    2005-11-01

    The IMAGE Wideband Imaging Camera (WIC) instrument observed the duskside development of an oval-aligned transpolar auroral arc (TPA) in the Northern Hemisphere (NH) on 16 December 2001 during strong IMF ?B? 18 nT and a generally steady 56 clock angle (positive IMF By and Bz). Observational evidence suggests that the dayside part of the duskside TPA formed due to quasi-continuous merging between the IMF and the lobe magnetic field tailward of the cusp while the nightside part is associated with the Harang discontinuity. The low-altitude CHAMP satellite confirms an upward northward IMF Bz (NBZ) field-aligned current (FAC) over the dayside TPA while associating a downward NBZ current with the region of diminished WIC emissions in between the auroral oval and the TPA. DMSP F14 suggests that the dayside region of the downward NBZ current coincides with precipitating magnetosheath-like ions of reversed energy-latitude dispersion consistent with high-latitude reconnection. SuperDARN observes enhanced ionospheric sunward flows generally centered between the oppositely directed NBZ currents. We associate these flows with a clockwise lobe convection vortex and the dayside part of the TPA. The nightside TPA, however, is related to stagnant or antisunward flow and the upward FAC region of the Harang discontinuity. Cluster observations confirm the simultaneous presence of rotational discontinuities across the duskside magnetopause with changes in the magnetosheath plasma velocity that indicate an active merging region poleward of Cluster. A global MHD simulation generates sunward flow between a pair of opposite FACs on either side of a lobe reconnection site near (X, Y, Z)GSM = (-4.7, 5.4, 10.2) RE thus conforming with Cluster and SuperDARN expectations. The sense of these FACs agrees with the low-altitude NBZ observations.

  4. 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.

  5. 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.

  6. 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.

  7. Ionospheric research using digital ionosondes

    NASA Astrophysics Data System (ADS)

    Reinisch, B. W.; Bibl, K.

    1983-07-01

    New digital UF sounding techniques are used for the study of the high altitude and the equatorial ionosphere: Doppler and incidence angle measurements allow one to identify irregularities in the ionospheric plasma and to determine their velocities. In the drift mode of observation the Digisonde with a four antenna receiving array measured the plasma bulk motion at Goose Bay. The results show that the HF Doppler technique measures the plasma convection also observed by incoherent scatter and satellite techniques. Automatic scaling of Digisonde ionograms is now routinely carried out at the Goose Bay Ionospheric Observatory. The E and F region echo traces are reliably determined also under spread conditions. The Automatic Real Time Ionogram Scaler with True Height also finds all standard ionospheric parameters and the electron density profile in real time.

  8. 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.

  9. Plasma bubbles in the topside ionosphere: estimations of the survival possibilities

    NASA Astrophysics Data System (ADS)

    Sidorova, Larisa; Filippov, Sergey

    The study deals with the evaluation of the survival possibilities of the plasma bubbles, seen as He+ density depletions in the topside ionosphere. He+ density depletions (or subtroughs) are usually observed during a high solar activity at the topside ionospheric altitudes ( 1000 km) deeply inside the plasmasphere (L 1.3-3). They are considered as originating from equatorial plasma bubbles phenomena or as possible fossil bubble signatures. The estimation of the characteristic times of a life, diffusion and vertical drift transport of helium ions (He+ ) at the topside ionosphere heights of the low-/mid-latitude region was made. It is revealed, that the diffusion transport process is the fastest one (some minutes). Since the ionosphere plasma is magnetized plasma at the topside ionosphere heights, the diffusion processes are field-aligned. Plasma bubbles spread (due to diffusion processes) along the magnetic tubes. Their spreading becomes more and more significant in process of their uplifting. So extended bubbles look like `banana' with the extremities reaching the ionosphere heights in both the hemispheres. This scheme is also correct if the separate components are under considerations, namely He+ . On the other hand, it is well known, that the magnetic tube, partially "devastated" by a plasma bubble, is replenished extremely slowly. The tube replenishment time is proportionally L4 (i.e. Badin, JATP, 1994). For example, it takes 10 hours for refilling the tube (L=2, 45o INVLAT), partially "devastated" or depleted by plasma bubble. It was concluded, that, if some plasma bubbles can reach the topside and plasmashere heights, they can exist here (may be as "dead" bubbles) during some hours. It was also concluded, that there is enough time to register the plasma bubbles at the topside ionosphere heights.

  10. Ionosphere density variations and formation of plasma bubbles caused by thunderstorm currents

    NASA Astrophysics Data System (ADS)

    Kuo, C.; Lee, L. C.; Hsu, R.; Huba, J. D.

    2012-12-01

    The charges and currents associated with a thunderstorm may interact with the middle atmosphere and the ionosphere. Thunderstorm charges may redistribute following the lightning stroke. The transient changes of quasi electric field associated with thunderstorm charge change may cause the transient luminous events, which include elves, halos, sprites, and gigantic jets. In this presentation, we examine the effects of thunderstorm current system on the ionosphere. We use a thunderstorm model to calculate the three-dimensional current flows in the atmosphere and to mimic the upward current above the typical dipolar charge structure inside the thunderstorm. The upward current flows into the ionosphere, while the associated electric field causes the plasma ExB drift motion. The caused plasma motion redistributes the plasma density, leading the variation of TEC. In the nighttime ionosphere, the ExB motion may also cause the formation of the plasma bubbles. We also simulate the effects of thunderstorm charges and flash rates on the ionosphere dynamics, e.g., ionospheric density variations and triggered plasma bubbles.

  11. Comparative studies of multi-scale convective transport through the Earth's plasma sheet

    NASA Astrophysics Data System (ADS)

    Guild, Timothy Bryan

    In this dissertation we explore multi-scale, convective transport through the Earth's plasma sheet using in situ observations and global terrestrial magnetospheric simulations. We statistically test the Lyon-Fedder-Mobarry (LFM) global magnetohydrodynamic (MHD) model with observations from the Geotail spacecraft at a variety of spatial and temporal scales within the plasma sheet. These comparisons, in addition to quantifying the LFM range of validity, illuminate model shortcomings and highlight the additional physics necessary to resolve data/model discrepancies. First, we perform the first ever comprehensive validation of the LFM in the plasma sheet. We show that the LFM largely reproduces global, long-term average plasma sheet properties and variability, but we also identify and characterize its systematic deficiencies. We find that the LFM overestimates the average plasma sheet velocity, and show that a portion of this overestimate is reflected in excessive LFM ionospheric transpolar potential (15%), and a portion of it is due to insufficient simulation resolution (15%). By characterizing the LFM plasma sheet velocity distribution as a function of simulation resolution, we find that increased resolution inherently changes the nature of the dynamics and transport within the LFM plasma sheet, bringing it into closer agreement with magnetotail observations containing fast, localized bulk flows. To perform the data/model comparisons described thus far, we construct one of the largest central plasma sheet data set of Geotail observations to date. Using this comprehensive data set, we investigate the equatorial distributions of fast, convective flows and infer that the Earthward extent of the average neutral line, the most likely location of near-Earth reconnection, is convex relative to the Earth and offset toward dusk. Due to the importance of these fast flows to mass, momentum, and energy transport in both the observed and simulated plasma sheets, we use the LFM to establish that locally-reconnecting magnetic lobe field lines initiate simulated "flow channels", explore the instability governing their subsequent evolution, and examine their similarity to observations of bursty bulk flows. This dissertation demonstrates the fruitful augmentation of sparse, statistical plasma sheet data sets with global MHD models, thereby enabling further exploration of the multi-scale nature of convective transport within the global, time-dependent plasma sheet.

  12. 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.

  13. 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.

  14. Correlation between the global occurrences of ionospheric irregularities and deep atmospheric convective clouds in the intertropical convergence zone (ITCZ)

    NASA Astrophysics Data System (ADS)

    Su, Shin-Yi; Wu, Chung Lung; Liu, Chao Han

    2014-12-01

    To study the seeding mechanism of ionospheric irregularity occurrences, a correlation study has been carried out between the global monthly/latitudinal (m/l) distributions of irregularity occurrences and the deep atmospheric convective clouds in the intertropical convergence zone (ITCZ) indicated by the outgoing longwave radiation (OLR) measurements. Seven longitude sectors - the African, Indian, West Pacific, Central Pacific, East Pacific, South American, and Atlantic sectors - are selected to study the correlations between the two distributions. The results indicate that good correlations exist only in the South American sector and to some extent in the African sector. For the other five sectors, no correlations are found in the m/l distributions between the irregularities and OLRs. This implies that the gravity wave induced in the ITCZ cannot be the sole seeding agent for the Rayleigh-Taylor (RT) instability in the global irregularity occurrences every season. We suspect that the post-sunset ionospheric electrodynamic perturbations could be the prevailing seeds for the RT instability globally year long. Together with the favorable post-sunset ionospheric condition, the global m/l distributions of irregularity occurrences could be adequately explained.

  15. Response of Aurorae, Plasma Convection, and Birkeland Currents to Strong IMF By and Negative Bz Conditions

    NASA Astrophysics Data System (ADS)

    Sandholt, P.; Farrugia, C.

    2006-05-01

    In a number of case event studies we probe the association between dayside auroral forms/activities and plasma convection channels (pulsed ionospheric flows) located at the dayside polar cap boundary during By-dominated IMF conditions when a negative Bz-component is also present (clock angle range 90-135°). Both polarities of IMF By are included. We base our results on (i) ground auroral observations at high latitudes (70-80° MLAT) and (ii) particle precipitation, ion drift, and Birkeland current measurements made by the DMSP F13 spacecraft. The following auroral types in the system of forms and activities within the merging and lobe convection cells are noted: (i) cusp 1 aurora ("midday gap"), (ii) cusp 2 aurora in the postnoon sector (By > 0 ), (iii) dayside BPS/LLBL aurorae in the pre- and postnoon sectors, (iv) poleward moving auroral forms (PMAFs) in the mantle regime, and (v) polar arcs on the pre- and postnoon sides of the polar cap. We investigate how these auroral forms evolve in space and time during magnetopause reconnection events. Our goal is to obtain a comprehensive picture of the complex system of dayside and polar cap auroral forms and convection channels contributing to the large-scale pattern of plasma convection/precipitation with the dawn-dusk asymmetry imposed by the IMF By-component. Emphasis is placed on small- and medium-scale structures. These are often averaged out in large statistical studies. This work is supported in part by NASA Grants NNG05GG25G and NNG05GC75G

  16. 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.

  17. 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.

  18. Titan's Topside Ionospheric Composition: Cassini Plasma Spectrometer Ion Mass Spectrometer Measurements

    NASA Astrophysics Data System (ADS)

    Sittler, EC; Hartle, RE; Ali, A.; Cooper, JF; Lipatov, AS; Simpson, DG; Sarantos, M.; Chornay, DJ; Smith, HT

    2015-10-01

    We present ion composition measurements of Titan's topside ionosphere using T15 Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS) measurements. The IMS is able to make measurements of Titan's ionosphere due to ionospheric outflows as originally reported by [1] for the T9 flyby. This allows one to take advantage of the unique capabilities of the CAPS IMS which measures both the mass-per-charge (M/Q) of the ions and the fragments of the ions produced inside the sensor such as carbon, nitrogen and oxygen fragments. Specific attention will be given to such ions as NH4+, N+, O+, CH4+, CxHy+, and HCNH+ ions as examples.

  19. The Role of the Ionosphere in Providing Plasma to the Terrestrial Magnetosphere—An Historical Overview

    NASA Astrophysics Data System (ADS)

    Chappell, Charles R.

    2015-10-01

    Through the more than half century of space exploration, the perception and recognition of the fundamental role of the ionospheric plasma in populating the Earth's magnetosphere has evolved dramatically. A brief history of this evolution in thinking is presented. Both theory and measurements have unveiled a surprising new understanding of this important ionosphere-magnetosphere mass coupling process. The highlights of the mystery surrounding the difficulty in measuring this largely invisible low energy plasma are also discussed. This mystery has been solved through the development of instrumentation capable of measuring these low energy positively-charged outflowing ions in the presence of positive spacecraft potentials. This has led to a significant new understanding of the ionospheric plasma as a significant driver of magnetospheric plasma content and dynamics.

  20. SuperDARN convection and Sondrestrom plasma drift

    NASA Astrophysics Data System (ADS)

    Xu, L.; Koustov, A. V.; Thayer, J.; McCready, M. A.

    2001-07-01

    Plasma convection measurements by the Goose Bay and Stokkseyri SuperDARN radar pair and the Sondrestrom incoherent scatter radar are compared in three different ways, by looking at the line-of-sight (l-o-s) velocities, by comparing the SuperDARN vectors and corresponding Sondrestrom l-o-s velocities and by comparing the end products of the instruments, the convection maps. All three comparisons show overall reasonable agreement of the convection measurements though the data spread is significant and for some points a strong disagreement is obvious. The convection map comparison shows 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). On average, both effects do not exceed 35%. Data indicate that inconsistencies between the two data sets occur largely at times of fast temporal variations of the plasma drift and for strongly irregular flow ac-cording to the SuperDARN convection maps. These facts indicate that the observed discrepancies are in many cases a result of the different spatial and temporal resolutions of the instruments.

  1. Behavior of thermal plasma in the ionosphere and magnetosphere

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    Models of ion flow in the topside ionosphere were developed. These models took both H(+) and O(+) into account and permitted various parameter studies to be made affecting H(+) escape in polar winds. Extensive computer programs were written to display the measured electron density profiles in ways useful to geophysical analysis. The relationship between the location of the plasmapause as it is found in the equatorial plane and the location of the ionospheric trough was also investigated.

  2. 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 different directions (shear) in a convection patterns. Region 2 and region 0 currents were observed equatorward and northward of region 1 currents, respectively. (Abstract shortened by UMI.)

  3. 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.

  4. 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.

  5. Understanding the Earth's ionosphere as a fully sufficient source for magnetospheric plasma

    NASA Astrophysics Data System (ADS)

    Huddleston, Matthew Mark

    One of the most significant questions remaining in space physics concerns the ultimate fate of ionospheric plasma outflows and their relative contribution to the plasma populations within the magnetosphere. A growing number of ionospheric outflow studies over the past two decades have cast serious doubt on the traditional view of solar wind as a dominant source of magnetospheric plasma. A unique approach combining data and modeling have been used here to demonstrate that the earth's ionosphere is fully capable of providing the magnetosphere with plasma at energies and densities that are consistent with observations. The first detailed statistical analysis of pitch angle and energy distributions of polar wind (<3.5 eV) outflows has been performed using data from the Thermal Ion Dynamics Experiment (TIDE) on board the Polar spacecraft. A new method of accounting for spacecraft charging effects has been used, providing improved estimates of the true polar wind outflow characteristics. The results of this polar wind analysis are used together with known cleft ion fountain (CIF) and auroral source characteristics as input to a single particle trajectory code that traces ion motion throughout magnetospheric electric and magnetic fields. The results of numerous model trajectories suggest that ion drifts through magnetospheric electric fields are capable of accelerating terrestrial ions out to the distant magnetotail where they are further accelerated to plasma sheet and ring current energies. Ion flow characteristics, energies, and densities as calculated from the model agree closely with observations. Polar wind from the dayside ionosphere appears to be the dominant source for magnetospheric H+ ions, while auroral ions play a surprisingly minor role in plasma sheet refilling and ring current formation. Cold populations (<50 eV) of ionospheric material appear to exist throughout much of the outer magnetosphere that would be difficult to detect with current orbiting particle instruments. Renewed efforts are needed throughout the space physics community to address the implications of the ionosphere the dominant source of plasma for the magnetosphere.

  6. 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.

  7. Response time of the polar ionospheric convection pattern to changes in the north-south direction of the IMF. Scientific report No. 1

    SciTech Connect

    Hairston, M.R.; Heelis, R.A.

    1995-03-01

    A three day period from January 27 through January 29, 1992 is analyzed using one minute resolution solar wind data from the IMP8 satellite and the ionospheric convection pattern data derived from the four operational DMSP satellites. During this period there were several clear reversals of the sign of the z component of the interplanetary magnetic field (IMF) which is known to have a direct effect on the convection patterns observed in the polar ionosphere. Polar convection patterns observed by the frequent passes of four DMSP satellites are examined following each sign change to determine the time lag between the change in the IMF at the magnetopause and the establishment of a new global convection signature in the ionosphere. After removing the transit time for the IMF to travel from the position of the IMP-8 satellite to the magnetopause, a further time lag of about 17 to 25 minutes is observed for the five cases where the IMF turned from northward to southward. A longer lag of between 28 and 44 minutes is observed for the two cases where the IMF turned from southward to northward. These lags are interpreted as the inertial response time of the ionosphere in reacting to the change in the IMF.

  8. 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 10-19 RS and from July 1st, 2004 to . Hot electron densities peak near 9 RS and decrease radially at a rate of 1/r3, which suggests a source in the inner magnetosphere. We also observe a decrease in electron energy at a rate of 1/r3 due to the conservation of the first adiabatic invariant, consistent with radial transport through a magnetic dipole. Data from the magnetic field instrument is used to derive the magnetic moment of hot electrons which shows a constant value of 103.4 kgm2s-2 nT-1 +/-10 between 10-19 RS, indicating a loss-free adiabatic transport with minor fluctuations. Plasma transport at Saturn can occur through flux tube interchange instabilities within the magnetosphere, where cold dense plasma is transported radially outward while hot tenuous plasma from the outer magnetosphere moves radially inward. Gradient-curvature drifts cause these hot electrons leave the injection and superimpose on the ambient cold plasma, consequently forcing it to move radially outward. This implies flux-tube interchange to be the main source for hot electrons. Hot electrons are part of the plasma analysis for which CAPS was designed, while the MIMI-LEMMS instrument measures higher energy electrons. Taking into account the penetrating background radiation, we are able to derive information for these energetic particles using our plasma instruments. We present CAPS-IMS background measurements derived from plasma data and show strong correlation with high energy particle data from MIMI-LEMMS. IMS background is generated via two main processes: 1) Collisions between the instrument walls and ambient energetic particles, which cause X-rays to trigger count signals in the instrument optics, and 2) backscatter of energetic particles in the electrostatic analyzer. We quantify these effects and use the results to identify Saturn's radiation belt peaks and nadirs, and magnetospheric regions of depleted particle fluxes, or microsignatures, which are formed through interactions with moons and ring systems. Using methods described in [119] we analyze a moon microsignatures during the outbound phase of Saturn orbit insertion (2004-183) and inside the orbit of Mimas, a region of intense radiation. Using the physical characteristics and radial locations of Atlas, Prometheus, and Pandora we derive the radial diffusion coefficient to be less than 1 x10-9 and particle energies to be below 1 MeV.

  9. High-speed flow and high temperature plasma in Saturn's mid-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Sakai, Shotaro; Watanabe, Shigeto

    The Cassini spacecraft observations showed that the peak density of the electron was about 10 (10) m (-3) at 1300 km and the electron density decreased to about 10 (8) m (-3) at 10000 km. In some models the topside electron density distribution with the temperature of about 500 K was consistent with the observations. However, those models did not include the Saturn's magnetospheric effect and the models calculated the plasma parameters below 4000 km altitudes. We have developed an ionospheric model including the magnetospheric plasma temperature of 2 eV as a boundary condition. The results showed that the plasma temperatures were 2000 K at 1000 km and 20000 K at 10000 km, respectively. This indicates that the ionospheric temperature is significantly affected by the joule heating at low altitudes and the heat flow from the magnetosphere at high altitudes. The plasma density was about 10 (10) m (-3) at 1200 km, and it decreased to about 10 (7) m (-3) at 10000 km. The dominant ions were H _{3}(+) between 1000 and 10000 km, and H _{X}O (+) below 1000 km, respectively. The light ions accelerated by the centrifugal force flow upward at low altitudes. We suggest that the similar high-speed flow could occur in planets with the fast rotation. The peak density varied between about 10 (8) and 10 (10) m (-3) during one Saturn's day, but the electron temperature distribution didn't change on the local time. The ionospheric Pedersen conductivity estimated from the ionospheric plasma density depended on the local time and it was between 0.30 and 0.77 S. Since the ionospheric Pedersen conductivity strongly affects the electric field in the inner magnetosphere generated by a dust-plasma interaction, we suggest that the magnetosphere-ionosphere coupling is significantly important for the Saturn's inner magnetospheric physics.

  10. Interaction of Precipitating Electrons with Ionospheric Plasma: Acceleration of Ionospheric Electrons

    NASA Astrophysics Data System (ADS)

    Galinsky, V. L.; Ride, S. K.; Shevchenko, V. I.

    1997-11-01

    The tail heating of the ionospheric electrons due to Landau resonant interaction with lower hybrid waves in the auroral ionosphere is studied. The waves are excited due to so-called fan instability based on an anomalous Doppler resonance of waves with precipitating electrons^1. A hybrid method of incomplete numerical simulations in concert with the spectral method are used to investigate the dynamics of electron acceleration. Results of modeling are compared with experimental data^2. ^1Yu. A. Omelchenko, V.D. Shapiro, V.I. Shevchenko, M. Ashour-Abdalla and D. Schriver, J. Geophys. Res. 99, 5965 (1994). ^2K.A. Lynch, R.L. Arnoldy, P.M. Kintner and J.L. Vago, J. Geophys. Res. 99, 2227 (1994).

  11. Global Coupled Model Studies of The Jovian Upper Atmosphere In Response To Electron Precipitation and Ionospheric Convection Within The Auroral Region.

    NASA Astrophysics Data System (ADS)

    Millward, G. H.; Miller, S.; Aylward, A. D.

    The Jovian Ionospheric Model (JIM) is a global three-dimensional model of Jupiter's coupled ionosphere and thermosphere, developed at University College London. Re- cently, the model has been used to investigate the atmospheric response to electron precipitation within the high-latitude auroral region. A series of simulations have been performed in which the model atmosphere is subjected to monochromatic precipitat- ing electrons of varying number flux and initial energy and, in addition, to various degrees of ionospheric convection. The auroral ionospheric conductivity which re- sults is shown to be strongly non-linear with respect to the incoming electron energy, with a maximum observed for incident particles of initial energy 60 KeV. Electrons with higher energies penetrate the thermospheric region completely, whilst electrons of lower energy (say 10 keV) produce ionisation at higher levels in the atmosphere which are less less condusive to the creation of ionospheric conductivity. Studies of the thermospheric winds with the auroral region show that zonal winds (around the auroral oval) can attain values of around 70% of the driving zonal ion velocity. Also the results show that these large neutral winds are limited in vertical extent to the region of large ionospheric conductivity, tailing off markedly at altitudes above this. The latest results from this work will be presented, and the implications for Jovian magnetospheric-ionospheric coupling will be discussed.

  12. A comparison of plasma waves produced by ion accelerators in the F-region ionosphere

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Labelle, J.; Scales, W.; Erlandson, R.; Cahill, L. J., Jr.

    1986-01-01

    Ion beams injected into the ionosphere are known to produce waves related to the normal modes of the plasma. The spectra of plasma waves produced during four sounding rocket experiments are examined. The experimental conditions were somewhat different during each experiment. The accelerated ion was either Xe(+) or Ar(+) and the experimental geometry, described by the separation vector between the plasma wave receiver and the ion accelerator, was either parallel or perpendicular to the geomagnetic field.

  13. Yosemite conference on ionospheric plasma in the magnetosphere: sources, mechanisms and consequences, meeting report

    SciTech Connect

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

    1987-02-01

    The sixth biennial Yosemite topical conference and the first as a Chapman Conference was held on February 3 to 6, 1986. 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.

  14. Development of suprathermal plasma analyzer (SPA) for ionospheric sounding

    NASA Astrophysics Data System (ADS)

    Shimoyama, M.; Abe, T.; Oyama, K.-I.

    Processes of energy transfer from suprathermal to thermal electrons have been poorly understood mainly because of a lack of observations though they significantly affect the thermal structure of the lower ionosphere and play an important role in the energy budget We have developed an instrument to measure the electron energy distribution in the thermal and suprathermal energy range 5 eV for the sounding rocket The innovative combination of Druyvesteyn method and a channel electron multiplier CEM enables us to measure an energy distribution of suprathermal electrons whose flux is much smaller than thermal electrons with high-energy resolution Outstanding points of this instrument are 1 accurate calibration of electron energy within the order of 0 01 eV and 2 energy resolution smaller than 0 15 eV For a safe operation of a CEM in the lower ionosphere this instrument is equipped with a differential pumping system We have also carried out a laboratory simulation in order to investigate the energetics of the lower ionosphere as well as to confirm the ability of the developed instrument Several specific structures in the energy distribution are found to exist at a certain energy range and some are identified as the product of inelastic collisions of electrons with neutral particles The electron energy distribution obtained by the past sounding rocket experiment in the lower ionosphere shows the structure extremely similar to that of the present experiment This consistency indicates the existence of energy transfer from neutral particles to thermal electrons

  15. Spacelab-2 plasma depletion experiments for ionospheric and radio astronomical studies.

    PubMed

    Mendillo, M; Baumgardner, J; Allen, D P; Foster, J; Holt, J; Ellis, G R; Klekociuk, A; Reber, G

    1987-11-27

    The Spacelab-2 Plasma Depletion Experiments were a series of studies to examine shuttle-induced perturbations in the ionosphere and their application to ground-based radio astronomy. The space shuttle Challenger fired its orbital maneuvering subsystem engines on 30 July and 5 August 1985, releasing large amounts of exhaust molecules (water, hydrogen, and carbon dioxide) that caused the electrons and ions in Earth's upper atmosphere to chemically recombine, thereby creating so-called "ionospheric holes." Two burns conducted over New England produced ionospheric peak depletions ranging from 25 to 50 percent, affected the ionosphere over a 200-kilometer altitude range, and covered 1 degrees to 2 degrees of latitude. Optical emissions associated with the hole spanned an area of several hundred thousand square kilometers. A third burn was conducted over a low-frequency radio observatory in Hobart, Australia, to create an "artificial window" for ground-based observations at frequencies normally below the natural ionospheric cutoff (penetration) frequency. The Hobart experiment succeeded in making high-resolution observations at 1.7 megahertz through the induced ionospheric hole. PMID:17744364

  16. Plasma convection and ion beam generation in the plasma sheet boundary layer

    NASA Technical Reports Server (NTRS)

    Moghaddam-Taaheri, E.; Goertz, C. K.; Smith, R. A.

    1991-01-01

    Because of the dawn-dusk electric field E(dd), plasma in the magnetotail convects from the lobe toward the central plasma sheet (CPS). In the absence of space or velocity diffusion due to plasma turbulence, convection would yield a steady state distribution function f = V exp (-2/3) g(v exp 2 V exp 2/3), where V is the flux tube volume. Starting with such a distribution function and a plasma beta which varies from beta greater than 1 in the CPS to beta much smaller than 1 in the lobe, the evolution of the ion distribution function was studied considering the combined effects of ion diffusion by kinetic Alfven waves (KAW) in the ULF frequency range (1-10 mHz) and convection due to E(dd) x B drift in the plasma sheet boundary layer (PSBL) and outer central plasma sheet (OCPS). The results show that, during the early stages after launching the KAWs, a beamlike ion distribution forms in the PSBL and at the same time the plasma density and temperature decrease in the OCPS. Following this stage, ions in the beams convect toward the CPS resulting in an increase of the plasma temperature in the OCPS.

  17. 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.

  18. A method to derive maps of ionospheric conductances, currents, and convection from the Swarm multisatellite mission

    NASA Astrophysics Data System (ADS)

    Amm, O.; Vanhamäki, H.; Kauristie, K.; Stolle, C.; Christiansen, F.; Haagmans, R.; Masson, A.; Taylor, M. G. G. T.; Floberghagen, R.; Escoubet, C. P.

    2015-04-01

    The European Space Agency (ESA) Swarm spacecraft mission is the first multisatellite ionospheric mission with two low-orbiting spacecraft that are flying in parallel at a distance of ~100-140 km, thus allowing derivation of spatial gradients of ionospheric parameters not only along the orbits but also in the direction perpendicular to them. A third satellite with a higher orbit regularly crosses the paths of the lower spacecraft. Using the Swarm magnetic and electric field instruments, we present a novel technique that allows derivation of two-dimensional (2-D) maps of ionospheric conductances, currents, and electric field in the area between the trajectories of the two lower spacecraft, and even to some extent outside of it. This technique is based on Spherical Elementary Current Systems. We present test cases of modeled situations from which we calculate virtual Swarm data and show that the technique is able to reconstruct the model electric field, horizontal currents, and conductances with a very good accuracy. Larger errors arise for the reconstruction of the 2-D field-aligned currents (FAC), especially in the area outside of the spacecraft orbits. However, even in this case the general pattern of FAC is recovered, and the magnitudes are valid in an integrated sense. Finally, using an MHD model run, we show how our technique allows estimation of the ionosphere-magnetosphere coupling parameter K, if conjugate observations of the magnetospheric magnetic and electric field are available. In the case of a magnetospheric multisatellite mission (e.g., the ESA Cluster mission) several K estimates at nearby points can be generated.

  19. 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

    2016-04-01

    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.

  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. 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 altitude ISS orbit. Evidence of waves in the ion collection current data is seen in geographic zones known to exhibit the spread-F phenomenon. An anomaly in the current collection characteristic of the cylindrical probe appears also too be organized by the geomagnetic field.

  2. Global magnetospheric perturbations stimulated by the plasma wave discharge in the lower ionosphere

    SciTech Connect

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

    1994-12-01

    In this paper we discuss a new method of controlled stimulation of global perturbations and the diagnostics of plasma physical processes in the ionosphere and the magnetosphere of the Earth. The method was realized with a series of rocket experiments by means of excitation of the radio frequency plasma wave discharge in the near field of the dipole antenna. We focus considerable attention on the results obtained in these experiments testifying to the wide choice and diversity of potentialities of this new method.

  3. 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.

  4. 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.

  5. Io's atmosphere and ionosphere - New limits on surface pressure from plasma models

    NASA Technical Reports Server (NTRS)

    Johnson, T. V.; Matson, D. L.; Carlson, R. W.

    1976-01-01

    The paper studies charge particle impact as a mechanism for the production of Io's ionosphere. Pioneer 10 thermal plasma measurements and magnetospheric plasma models which explain the observed spatial distribution of neutral hydrogen and sodium atoms in the vicinity of Jupiter's satellite Io imply electron fluxes of about 10 to the 10th/sq cm/s. The fluxes and the temperature (about 100 eV) of this plasma suggest that electron impact ionization is the dominant process in forming the ionosphere of Io. It is found that the surface number density of the neutral species required to match the observed electron density profiles is about 10 to the 9th/cu cm or less. This value is two orders of magnitude lower than previous estimates.

  6. 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

  7. Ionospheric plasma density variations observed at Mars by MAVEN/LPW

    NASA Astrophysics Data System (ADS)

    Andrews, D. J.; Andersson, L.; Delory, G. T.; Ergun, R. E.; Eriksson, A. I.; Fowler, C. M.; McEnulty, T.; Morooka, M. W.; Weber, T.; Jakosky, B. M.

    2015-11-01

    We report on initial observations made by the Langmuir Probe and Waves relaxation soundingexperiment on board the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. These measurements yield the ionospheric thermal plasma density, and we use these data here for an initial survey of its variability. Studying orbit-to-orbit variations, we show that the relative variability of the ionospheric plasma density is lowest at low altitudes near the photochemical peak, steadily increases toward higher altitudes and sharply increases as the spacecraft crosses the terminator and moves into the nightside. Finally, despite the small volume of data currently available, we show that a clear signature of the influence of crustal magnetic fields on the thermal plasma density fluctuations is visible. Such results are consistent with previously reported remote measurements made at higher altitudes, but crucially, here we sample a new span of altitudes between ˜130 and ˜300 km using in situ techniques.

  8. 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.

  9. 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.

  10. Ionospheric energy inputs affecting plasma outflow and neutral upwelling

    NASA Astrophysics Data System (ADS)

    Olson, D. K.; Moore, T. E.; Coplan, M. A.

    2011-12-01

    Ion outflow in the ionosphere has shown evidence of correlation with both Poynting flux and soft electron precipitation in the cusp (Strangeway et al., JGR 2005). The heat input from these energy sources might also affect neutral gas in the ionosphere, contributing to upwelling phenomena seen at the dayside cusp (Lühr et al., GRL 2004). Using data from the Fast Auroral Snapshot Explorer (FAST) and the Challenging Minisatellite Payload (CHAMP) satellites, correlations of electromagnetic and particle energy inputs are examined with both ion outflow and neutral upwelling in the cusp. This study confirms the results from Strangeway 2005 and extends that study to include time periods throughout a solar cycle. Inclusion of CHAMP data expands the parameters to include data on the density of neutral gas at orbital altitudes. The added ability to process large quantities of data quickly and reference the data between separate satellites in this statistical survey gives clues to the consistency of the observed correlations with ion outflow over time and to the relative importance of these energy sources in the neutral upwelling phenomenon. It also provides the ability to understand these connections in a broad spectrum of conditions of the Sun and solar wind as well as in the Earth's magnetosphere. The data used in the analysis is available from U.C. Berkeley (FAST) and Helmholtz Centre Potsdam (CHAMP). Analysis is done with open sources tools including new Python libraries such as SpacePy (Morley et al., SciPy 2010).

  11. Intermediate scale plasma density irregularities in the polar ionosphere inferred from radio occultation

    NASA Astrophysics Data System (ADS)

    Shume, E. B.; Komjathy, A.; Langley, R. B.; Verkhoglyadova, O. P.; Butala, M.; Mannucci, A. J.

    2014-12-01

    In this research, we report intermediate scale plasma density irregularities in the high-latitude ionosphere inferred from high-resolution radio occultation (RO) measurements in the CASSIOPE (CAScade Smallsat and IOnospheric Polar Explorer) - GPS (Global Positioning System) satellites radio link. The high inclination of the CASSIOPE satellite and high rate of signal receptionby the occultation antenna of the GPS Attitude, Positioning and Profiling (GAP) instrument on the Enhanced Polar Outflow Probe platform on CASSIOPE enable a high temporal and spatial resolution investigation of the dynamics of the polar ionosphere, magnetosphere-ionospherecoupling, solar wind effects, etc. with unprecedented details compared to that possible in the past. We have carried out high spatial resolution analysis in altitude and geomagnetic latitude of scintillation-producing plasma density irregularities in the polar ionosphere. Intermediate scale, scintillation-producing plasma density irregularities, which corresponds to 2 to 40 km spatial scales were inferred by applying multi-scale spectral analysis on the RO phase delay measurements. Using our multi-scale spectral analysis approach and Polar Operational Environmental Satellites (POES) and Defense Meteorological Satellite Program (DMSP) observations, we infer that the irregularity scales and phase scintillations have distinct features in the auroral oval and polar cap regions. In specific terms, we found that large length scales and and more intense phase scintillations are prevalent in the auroral oval compared to the polar cap region. Hence, the irregularity scales and phase scintillation characteristics are a function of the solar wind and the magnetospheric forcing. Multi-scale analysis may become a powerful diagnostic tool for characterizing how the ionosphere is dynamically driven by these factors.

  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. 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.

  14. Magnetosphere of Uranus: plasma sources, convection, and field configuration

    SciTech Connect

    Voigt, G.; Hill, T.W.; Dessler, A.J.

    1983-03-01

    At the time of the Voyager 2 flyby of Uranus, the planetary rotational axis will be roughly antiparallel to the solar wind flow. If Uranus has a magnetic dipole moment that is approximately aligned with its spin axis, and if the heliospheric shock has not been encountered, we will have the rare opportunity to observe a ''pole-on'' magnetosphere as discussed qualitatively by Siscoe. Qualitative arguments based on analogy with Earth, Jupiter, and Saturn suggest that the magnetosphere of Uranus may lack a source of plasma adequate to produce significant internal currents, internal convection, and associated effects. In order to provide a test of this hypothesis with the forthcoming Voyager measurements, we have constructed a class of approximately self-consistent quantitative magnetohydrostatic equilibrium configurations for a pole-on magnetosphere with variable plasma pressure parameters. Given a few simplifying assumptions, the geometries of the magnetic field and of the tail current sheet can be computed for a given distribution of trapped plasma pressure. The configurations have a single funnel-shaped polar cusp that points directly into the solar wind and a cylindrical tail plasma sheet whose currents close within the tail rather than on the tail magnetopause, and whose length depends on the rate of decrease of thermal plasma pressure down the tail. Interconnection between magnetospheric and interplanetary fields results in a highly asymmetric tail-field configuration. These features were predicted qualtitatively by Siscoe; the quantitative models presented here may be useful in the interpretation of Voyager encounter results.

  15. 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 model of this boundary location and discuss the influence of solar wind.

  16. 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

  17. First storm-time plasma velocity estimates from high-resolution ionospheric data assimilation

    NASA Astrophysics Data System (ADS)

    Datta-Barua, Seebany; Bust, Gary S.; Crowley, Geoff

    2013-11-01

    This paper uses data assimilation to estimate ionospheric state during storm time at subdegree resolution. We use Ionospheric Data Assimilation Four-Dimensional (IDA4D) to resolve the three-dimensional time-varying electron density gradients of the storm-enhanced density poleward plume. By Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE), we infer the three-dimensional plasma velocity from the densities. EMPIRE estimates of ExB drift are made by correcting the Weimer 2000 electric potential model. This is the first time electron densities derived from GPS total electron content (TEC) data are being used to estimate field-aligned and field-perpendicular drifts at such high resolution, without reference to direct drift measurements. The time-varying estimated electron densities are used to construct the ionospheric spatial decorrelation in vertical total electron content (TEC) on horizontal scales of less than 100 km. We compare slant TEC (STEC) estimates to actual STEC GPS observations, including independent unassimilated data. The IDA4D density model of the extreme ionospheric storm on 20 November 2003 shows STEC delays of up to 210 TEC units, comparable to the STEC of the GPS ground stations. Horizontal drifts from EMPIRE are predicted to be northwestward within the storm-enhanced density plume and its boundary, turning northeast at high latitudes. These estimates compare favorably to independent Assimilative Mapping of Ionospheric Electrodynamics-assimilated high-latitude ExB drift estimates. Estimated and measured Defense Meteorological Satellite Program in situ drifts differ by a factor of 2-3 and in some cases have incorrect direction. This indicates that significant density rates of change and more accurate accounting for production and loss may be needed when other processes are not dominant.

  18. 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.

  19. HF radar observations of the F region ionospheric plasma response to Storm Sudden Commencements

    NASA Astrophysics Data System (ADS)

    Kane, T. A.; Makarevich, R. A.

    2010-07-01

    Performance of the Super Dual Auroral Radar Network (SuperDARN) HF radars during geomagnetic storms is investigated by analyzing the data collected during storm events over a 5-year period. Changes in the occurrence of F region HF backscatter observed by the 6 most equatorward radars are analyzed statistically using a superposed epoch analysis method with respect to a Storm Sudden Commencement (SSC). Regular diurnal variations of the echo occurrence during geomagnetically quiet days are produced and the amount of detected backscatter during storms is adjusted using quiet time curves. All radars considered in this study show a significant decrease in the number of detected echoes approximately 24 hours following SSC. Unexpected significant changes in occurrence levels are also present within a few hours of SSC, with most radars observing an increase in the amount of backscatter detected. The typical time evolution of F region echo occurrence is highly reminiscent of that of the electron density reported previously. Also considered is the ionospheric convection response to SSC observed by the zonally looking SuperDARN Unwin radar in New Zealand. It is shown that the initial response to SSC is instantaneous within uncertainty and appears to be independent of the magnetic latitude and local time. The observed convection response timing and morphology are discussed in the context of possible ionospheric propagation mechanisms.

  20. Enhancement of EM-Ionosphere interaction through Plasma Lens and Frequency Chirping

    NASA Astrophysics Data System (ADS)

    Pau, J.; Wong, A. Y.; Rosenthal, G.; Koziar, K. E.; Stone, K.

    2002-11-01

    During ionospheric modification, both satellite beacons and sky maps from digital ionosonde measurements have detected large-density perturbation. This perturbation reaches a maximum when the incident HF matches the plasma frequency on the density plateau (or at f_oF2 layer). Experiments and theories are presented which describe how a plasma lens can be created at a lower altitude by pre-conditioning the ionosphere at a lower altitude; the lowering of plasma density at the center of the heated region causes a change in the index of refraction, thereby forming an equivalent ionospheric lens^1. Unlike earlier results obtained at Arecibo Observatory^2 using water molecules injected by a rocket, our concept is simpler and can be repeated many times. Another enhancement of interaction comes from the chirping of the heating frequency such that all the waves converge at the resonant layer at a particular time^3. Work supported by SDSU. ^1 A.Y. Wong, Proceedings of Ionsopheric Interactions Workshop, Santa Fe, NM, April, 2002. ^2 M. Sulzer, private communication. ^3 S. Cowley and E. Valeo, private communication.

  1. Titan's plasma environment and ionosphere during the T85/T42/T32 magnetosheath encounters (Invited)

    NASA Astrophysics Data System (ADS)

    Edberg, N. J.; Andrews, D. J.; Shebanits, O.; Agren, K.; Wahlund, J.; Opgenoorth, H. J.; Garnier, P.; Roussos, E.; Cravens, T.; Badman, S. V.; Modolo, R.; Bertucci, C.; Dougherty, M. K.

    2013-12-01

    During the T85 flyby we observe the highest electron number densities ever reported from the ionosphere of Titan as measured by RPWS/LP. The measured density reached 4310 cm-3, which is at least 500 cm-3 higher than ever observed before, and at least 50 % above the average density for similar solar zenith angles. The peak of the ionospheric density is not reached on this flyby, making the maximum measured density a lower limit. Furthermore, we observe that Titan was located in the magnetosheath of Saturn for at least 2 h 45 min before the actual flyby. This long-term exposure to magnetosheath plasma and crossings of the magnetopause and bow shock might be the reason why the peak ionospheric electron density during T85 rise to the maximum recorded. We propose that enhanced fluxes of solar wind protons precipitating and causing particle impact ionoisation is the physical explanation for the extreme densities during T85. Measurements by RPWS/LP indicate from several flybys (T83-T91) that the electron density in the peak region of Titan's ionosphere (950-1100 km) has increased by about 15-30% during the last 2 years. Furthermore, the peak ionospheric density is found at lower altitudes, though the flyby geometry often affords only the inference of an upper-limit. The increase is most likely a response to the rising toward a new solar max with increasing EUV flux. Still, T85 stands out in terms of extreme densities. We compare the ionospheric structure and plasma environment of Titan during the T85 flyby to that of the previous T32/T42 magnetosheath encounter. T32 showed no apparent increased density in the peak region but that flyby occurred during the solar minimum era and close to the terminator plane of Titan. T42 on the other hand showed high electron densities despite the solar minimum conditions, but occurred at low solar zenith angles, where the ionospheric density normally is higher compared to high solar zenith angles. Orbital geometry and Cassini MAG measurements during the T85 magentosheath encounter.

  2. 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.

  3. Ionospheric Research with Miniaturized Plasma Sensors Aboard FalconSAT-3

    NASA Astrophysics Data System (ADS)

    Habash Krause, L.; Herrero, F. A.; Chun, F. K.; McHarg, M. G.

    2003-12-01

    Investigations into a novel technique to measure ionosphere-thermosphere parameters have culminated in the Flat Plasma Spectrometer (FLAPS) experiment, presently under development through a collaboration between NASA Goddard Space Flight Center (GSFC) and the U. S. Air Force Academy (USAFA). FLAPS is capable of providing measurements of the full neutral wind vector, full ion-drift velocity vector, neutral and ion temperatures, and deviations from thermalization. In addition, coarse mass spectroscopy is possible using an energy analysis technique. The suite of instruments is comprised of a set of 16 individual neutral and ion analyzers, each of which is designed to perform a specific function. Advances in miniaturization technology have enabled a design in which the 16-sensor suite resides on a circular microchannel plate with an effective area of 25 cm2. The FLAPS electronics package, consisting of low voltage and high voltage power supplies, a microprocessor, and Application Specific Integrated Circuit (ASIC) amplifiers, requires a volume of 290 cm3, power of 1.5 W, and a mass of 500 g. The suite requires a +5V regulated power line from the spacecraft, and the telemetry interface is a 5.0 V TTL-compatible serial connection. Data collection rates vary from 1 to 1000 (192 Byte) spectra per second. The motivation for the FLAPS experiment is driven by objectives that fall into both basic science and technology demonstration categories. Scientifically, there is strong interest in the effects of ionosphere-thermosphere coupling and non-thermalized plasma on the processes associated with equatorial F-region ionospheric plasma bubbles. These bubbles have been known to scintillate transionospheric propagation of radio waves, often resulting in disruptions of space-based communication and navigation systems. FLAPS investigations will assist in quantifying the impact of various processes on the instigation or suppression of plasma bubbles; certain outstanding questions include 1) What is the relevance of meridional winds in suppression of plasma bubble growth? 2) What role does a velocity space instability driven by non-thermalized plasma play in the generation of small scale (<1 km) bubbles? 3) What process is responsible for turbulence in plasma beyond the edges of a bubble structure? Technologically, the need for small yet capable instruments arises from the desire to make multipoint in situ measurements of "microscopic" plasma parameters to provide insight into "macroscopic" phenomena. Examples include coherency of spatial boundaries of large-scale ( ˜100 km) plasma bubbles, three dimensional structure of the equatorial wind and temperature anomaly, and vertical velocity gradients in the low latitude ionosphere. This paper provides an overview of the experiment motivation and instrument design of the FLAPS experiment.

  4. 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.

  5. Numerical modeling of the global changes to the thermosphere and ionosphere from the dissipation of gravity waves from deep convection

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    During the minimum of solar cycles 23-24, the Sun was extremely quiet; however, tropospheric deep convection was strong and active. In this paper, we model the gravity waves (GWs) excited by deep convective plumes globally during 15-27 June in 2009 and in 2000 (previous solar maximum). We ray trace the GWs into the thermosphere and calculate the body force/heatings which result where they dissipate. We input these force/heatings into a global dynamical model and study the neutral and plasma changes that result. The body forces induce horizontal wind (uH') and temperature (T') perturbations, while the heatings primarily induce T'. We find that the forces create much larger T' than the heatings. uH' consists of clockwise and counterclockwise circulations and "jet"-like winds that are highly correlated with deep convection, with |uH'|˜50-200m/s. uH' and T' are much larger during 2009 than 2000. uH' decreases slightly (significantly) with altitude from z˜150 to 400 km during 2009 (2000). T' perturbations at z=350km primarily propagate westward at ˜460 m/s, consistent with migrating tides. It was found that planetary-scale diurnal and semidiurnal tides are generated in situ in the thermosphere, with amplitudes ˜10-40m/s at z=250 km. The largest-amplitude in situ tides are DW1, D0, DW2, SW2, SW3, and SW5. Smaller-amplitude in situ tides are S0, SE2, and SW3. Total electron content (TEC') perturbations of 1-2.5 (2-3.5) total electron content units (TECU, where 1 TECU = 1016 el m-2) during 2009 (2000) are created in the upper atmosphere above nearby regions of deep tropical convection. For a given local time (LT), there are 2 to 3 TEC' peaks in longitude around the Earth.

  6. 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.

  7. 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 background F-region dynamo field, modulating the ionosphere fountain process. If the hypothesis about an equatorial origin of He (+) density depletions is true, we can suppose that such 4-peaked structure projected to the topside ionosphere are reflected in their longitudinal statistics. Perhaps this idea can be very useful for explanation of the obtained results. The results of this pioneer study suggest new investigation questions, based mainly on data lacking.

  8. 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.

  9. 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.

  10. 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 waves, study their propagation in the atmosphere, determine the intensity of the infrasonic waves generated in the ionosphere by the dust acoustic waves during Perseid, Orionid, Gemenid and Leonid meteor showers, and find frequency ranges where they can compete with the infrasonic waves from other sources. References [1] S.I. Musatenko, Yu.S. Musatenko, E.V. Kurochka, et al., 4-th Ukrainian Conf. Space Research (Kiev, 2004), p. 96. [2] S.V. Vladimirov, V.N. Tsytovich, S.I. Popel, and F.Kh. Khakimov, Modulational Interactions in Plasmas (Kluwer Academic Publishers, Dordrecht, 1995), 544 pages.

  11. 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.

  12. Characterization of the geometries of the high-latitude ionospheric convection pattern

    NASA Astrophysics Data System (ADS)

    Keating, Christopher Francis

    An investigation of the geometries of the high-latitude convection pattern is conducted using spacecraft observations of the northern hemisphere during conditions when the z-component of the interplanetary magnetic field is negative. In the first part of this investigation we examine the specification of the polar cap boundary as a circle using data from nearly simultaneous satellites to investigate the variation in size and location of the circle and the means by which such variations may be specified. We also investigate the degree to which a circle departs from the instantaneous configuration of the boundary and the effect that such departures may have on the global potential distribution. The DMSP satellites F8 and F9 provide an opportunity to identify the polar cap boundary with four nearly simultaneous points that can be used in a least squares fitting procedure to derive a best fit circle describing the polar cap boundary. The results of this exercise confirmed that the polar cap boundary can be well represented by a circle with the center offset towards the midnight sector with a B(sub y) and seasonal dependence in the radius of the circle and the location of the center point. Our results indicated that departures from a nominally circular boundary occur most frequently on the dayside. These departures led us to conclude that the polar cap boundary can be best represented by two circular segments with a smaller segment on the dawnside for conditions of B(sub y) negative. We also identified localized bulges or depressions as departures from the circle that are consistent with the descriptions of suggested impulsive additions of magnetic flux to the polar cap. In the second part of this investigation we examine the latitude distribution of the potential at latitudes below the polar cap boundary to determine its sensitivity to interplanetary conditions, magnetic activity, and local time. We use a gaussian curve segment to best represent the distribution of the potential equatorward of the polar cap and find the gaussian halfwidth is dependent on the potential at the polar cap boundary with the halfwidth being larger on the duskside than on the dawnside. We also find this parameter is dependent on local time as well as Kp and IMF B(sub z). In all cases, the halfwidth shows a greater variability on the duskside than on the dawnside. Finally, we note that the potential distribution around the polar cap boundary shows significant departures from the sinusoidal distribution frequently assumed in model treatments. As a final exercise, we use our results to generate inputs into a mathematical model of the high-latitude convection pattern and compare the results to measured data and find the model results to be reasonable representations of the actual conditions.

  13. Study plasma interactions in the auroral ionosphere. Final report

    SciTech Connect

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

    1983-09-01

    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.

  14. Slow ions in plasma wind tunnels. [satellite-ionosphere interaction

    NASA Technical Reports Server (NTRS)

    Oran, W. A.; Stone, N. H.; Samir, U.

    1976-01-01

    One of the limitations of simulation experiments for the study of interaction between a satellite and its space environment is the background of slow ions in the plasma chamber. These ions appear to be created by charge exchange between the beam ions and residual neutral gas and may affect measurements of the current and potential in the wake. Results are presented for a plasma wind tunnel experiment to study the effect of slow ions on both the ion and electron current distribution and the electron temperature in the wake of a body in a streaming plasma. It is shown that the effect of slow ions for beam ion density not exceeding 3 is not significant for measurements of ion current variations in the wake zone. This is not the case when studies are aimed at the quantitative examination of electron current and temperature variations in the near wake zone. In these instances, the measurements of electron properties in the wake should be done at very low system pressures or over a range of system pressures in order to ascertain the influence of slow ions.

  15. Alfven Waves and Electron Energization and Their Interaction with Auroral Ionospheric Plasma Transport

    NASA Astrophysics Data System (ADS)

    Jaafari, F. B.; Horwitz, J. L.; Jones, S.; Su, Y.; Zeng, W.

    2008-12-01

    When inertial Alfvén waves propagate along auroral field lines, they involve parallel electric fields which can accelerate auroral electrons. Here, we simulate the propagation of Alfvén waves through O+ and H+ auroral ionosphere-magnetosphere density profiles obtained from the UT Arlington Dynamic Fluid- Kinetic (DyFK) ionospheric plasma transport model. A linear one dimensional gyrofluid code [Jones and Parker, 2003] is used for the Alfvén wave description, incorporating electron inertia, electron pressure gradient and finite ion gyroradius effects. Then, the test particle approach of Su et al. [2004] is used to simulate the response of a distribution of electrons to these Alfvén wave electric fields. These electrons are incorporated into the DyFK model to produce a partially-self-consistent approach to producing the associated ionization and thermal electron heating within the ionosphere-magnetosphere system. Jones, S. T., and S. E. Parker (2003), Including electron inertia without advancing electron flow, J. Comput. Phys., 191, 322. Su, Y.-J., S. T. Jones, R. E. Ergun, and S. E. Parker (2004), Modeling of field-aligned electron bursts by dispersive Alfvén waves in the dayside auroral region, J. Geophys. Res., 109, A11201, doi:10.1029/2003JA010344.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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 midlatitude 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.

  17. 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.

  18. Ionospheric outflows as possible source of the low-energy plasma flux tubes controlling the dimension of pulsating auroral patches

    NASA Astrophysics Data System (ADS)

    Liang, J.; Donovan, E.; Nishimura, T.; Yang, B.; Angelopoulos, V.

    2014-12-01

    Conjunctive observations of low-Earth-orbit satellites and optical auroral imagers have indicated that, a majority of pulsating auroral patches (PAPs) are associated with low-energy ion (LEI) precipitation structures with core energies ranging from several tens of eV up to a few hundred eV. This result is consistent with a long-standing proposal that the PAPs connect to flux tubes filled with enhanced "cold" plasma. To further explore the origin and generation mechanism of those LEI structures, we investigate a few THEMIS events when the in-situ probes are conceived as conjugate to PAPs, judging by an apparent correlation between the in-situ whistler-mode chorus and the oscillation of the PAP luminosity [Nishimura et al., 2011]. We notice a common existence of LEI structures from THEMIS in-situ data during those conjugacy event intervals. Such LEI structures are always strongly field-aligned, with core energies ranging from several tens of eV up to a few hundred eV, and often exhibit distinct energy dispersion features. Contingent upon the energy range and time, the pitch-angle distribution of the LEI structures can be either heavily biased toward parallel direction, or biased toward anti-parallel direction, or roughly symmetric between parallel and anti-parallel directions. The above observations allude to the ion outflows from the ionosphere as a plausible origin of the observed LEI structures. To check the above notion, we perform particle simulations assuming that the low-energy ions originate from the ion outflows in topside ionosphere and bounce between hemispheres while convecting with EXB drift. The simulation results can reproduce some of the basic observable features of the LEI structures, such as the energy dispersion and the variation of pitch-angle distribution versus time and energy. Combining the results from low-Earth-orbit satellites observations, THEMIS in-situ observations, and simulations, we propose that the ion outflows into the magnetosphere can fill the flux tubes with low-energy plasma structure which, along with coherent dimension of the whistler-mode chorus and high-energy electron precipitation, control the spatial size of the PAP.

  19. Possible role of ionospheric oxygen in the initiation and development of plasma sheet instabilities

    SciTech Connect

    Baker, D.N.; Hones, E.W. Jr.; Young, D.T.; Birn, J.

    1982-12-01

    We relate measurements made during substorm growth and expansion to available plasma compositional observations and propose that asymmetries in the distribution of enhanced densities of O/sup +/ (of ionospheric origin) may define regions of the plasma sheet in which tearing mode growth rates are increased and the instability threshold is lowered. We make qualitative estimates of the growth rates of the linear ion tearing mode using statistical models of the dusk-dawn and earthward-tailward distributions of O/sup +/. The theoretical results predict maximum ion tearing growth rate in the range X/sub GSM/ = -10 to -15 R/sub E/ and Y/sub GSM/approx.5 R/sub E/. These values are in reasonable accord with substorm observations since many asymmetries in particle and field phenomena associated with substorms favor the interpretation that substorm onset occurs in the dusk sector of the near-earth plasma sheet. Present results therefore suggest that substorm initiation and development may be closely related to distribution patterns of ionospheric ions.

  20. 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.

  1. 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.

  2. Free Thermal Convection in Complex Plasma with Background-Gas Friction

    SciTech Connect

    Ivlev, A. V.; Zhdanov, S. K.; Morfill, G. E.

    2007-09-28

    The onset of free thermal convection in complex fluids with background friction is theoretically investigated. It is shown that in the limit when friction prevails--opposite to the classic Rayleigh-Benard case--the onset is determined by a renormalized Rayleigh number and also depends on the Prandtl number. Such convection should be observable in experiments with complex plasmas.

  3. Non-Uniform Plasma Discharges in Near Earth Space Environment and Ionosphere to Troposphere Responses

    NASA Astrophysics Data System (ADS)

    McCanney, J. M.

    2009-05-01

    Most earth weather and ionosphere-space environment coupling studies separate the problems into distinct groups. Heliosphere to solar wind - solar storm activity to ionospheric coupling - thermosphere and mid- altitude to the ionosphere and electrical effects such as elves and sprites and thunderstorms in another group - additionally mid and high latitude weather systems are many times separated also. The theoretical work here shows that not only are these areas coupled and related, but it also shows that without the constant electrical and resulting magnetic driving forces from space environments, earth would have little if no weather variability at all below the ionosphere. With only solar light energy as input, earth (and the other planets) would have little weather at all. The realization that extensive electrical activates occur in and above the troposphere, extending to the ionosphere and ultimately coupling to the magnetosphere have raised the theoretical and experimental questions regarding the sources of EMF which create the observed effects. The current work has identified 17 Local Electrical Batteries (LEBs), which provide the electrical EMF that can be linked to the observed effects the jet streams and lower atmospheric weather phenomenon. The path of the sources of EMF can be followed from the passing solar wind through "tunnels" that end in electrical currents that pass into the atmosphere via the ionosphere to storm cloud systems in the lower atmosphere. However the source of energy comes from localized plasma discharging of a non-uniform plasma environment that powers the electrical systems of the entire solar system. These are ultimately the sources of electrical energy that power the severe lower atmospheric storm systems such as westerly moving hurricanes at low latitudes and associated tornadoes. The connection is made theoretically with the solar wind that drives the 17 identified LEBs. The ultimate source of driving energy is the result of an excess current of protons in the solar wind, which creates an overall capacitor with inherent non-uniform electric field surrounding the Sun. On a local scale the voltage gradients are quite low, but all objects in this solar capacitor, including the planets and their moon systems, discharge this capacitor over extensive trans-planetary distances, thus creating excessive current flows, which also respond to CMEs and solar flares which carry a far greater potential gradient in the passing solar wind. The key to understanding reactions to non-uniform electric fields in the LEB environment is based on the fact that planetary Debye shielding takes on a new form, which is extended from that of the neutral environment typically considered in previous theoretical models. An attempt is made to solve the fundamental problem of the source of energy that drives these systems. The effects of moons and their positions relative to the planet and solar wind, as well as multiple planetary electrical alignments, are shown to contribute to the overall discharge phenomenon. A connection is made between these energy sources and cyclonic storms, earthquakes and volcanic "trigger" mechanisms. The goal of this research is to create an overall space weather model that couples the single energy source (the non-uniform plasma environment of the Sun created by an excess current of positive charge in the solar wind) to the earth's magnetosphere and ionosphere (and other planetary environments) and ultimately to the low altitude weather systems.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  6. Modeling magnetospheric plasma; Proceedings of the First Huntsville Workshop on Magnetosphere/Ionosphere Plasma Models, Guntersville, AL, Oct. 14-16, 1987

    NASA Technical Reports Server (NTRS)

    Moore, T. E. (Editor); Waite, J. H., Jr. (Editor)

    1988-01-01

    The conference presents papers on the global modeling of magnetospheric plasma processes, the modeling of the midlatitude ionosphere and plasmasphere, the modeling of the auroral zone and boundary layer, the modeling of the polar magnetosphere and ionosphere, and the modeling of the plasma sheet and ring current. Particular attention is given to the kinetic approach in magnetospheric plasma transport modeling, self-consistent neutral point current and fields from single particle dynamics, preliminary statistical survey of plasmaspheric ion properties from observations by DE 1/RIMS, and a model of auroral potential structures based on dynamics explorer plasma data. Other topics include internal shear layers in auroral dynamics, quantitative parameterization of energetic ionospheric ion outflow, and open flux merging in an expanding polarcap model.

  7. Development of beam-plasma instability during the injection a low-energy electron beam into the ionospheric plasma

    SciTech Connect

    Baranets, N. V.; Sobolev, Ya. P.; Ciobanu, M.; Vojta, J.; Smilauer, J.; Klos, Z.; Rothkaehl, H.; Kiraga, A.; Kudela, K.; Matisin, J.; Afonin, V. V.; Ryabov, B. S.; Isaev, N. V.

    2007-12-15

    Results are presented from an active experiment on the injection of charged particle beams into the ionospheric plasma. The experiment was carried out in 1992 onboard the Intercosmos-25 satellite and the Magion-3 daughter satellite (APEX). A specific feature of this experiment was that both the ion and electron beams were injected upward, in the same direction along the magnetic field. The most interesting results are the excitation of HF and VLF-LF waves and the generation of fast charged particle flows, which were recorded on both satellites.

  8. Magnetospheric interaction with Triton's ionosphere

    SciTech Connect

    Strobel, D.F.; Cheng, A.F. ); Summers, M.E. ); Strickland, D.J. )

    1990-09-01

    The large electron densities measured by the Voyager radio occultation experiment are attributed to the precipitation of magnetospheric electrons with energy > 10 keV. Because the ionospheric electric Pedersen conductivity of Triton is {approximately} (1-2) {times} 10{sup 4} mho and the Alfven conductance is {approximately} 3.5 mho, direct convective flow of plasma into the essentially infinitely conducting ionosphere is negligible. Magnetospheric electrons are transported to Triton's ionopause by curvature drift as a result of weak magnetic field line draping in a sub-Alfvenic plasma interaction with Triton. At the ionopause energetic and inelastic scattering and precipitate into the upper atmosphere. The average power dissipation is estimated to be {approximately} (2-3) {times} 10{sup 8} W.

  9. Dynamics of three-dimensional plasma clouds with coupling to the background ionosphere

    NASA Technical Reports Server (NTRS)

    Ma, T.-Z.; Schunk, R. W.

    1994-01-01

    A three-dimensional, time-dependent model with a two-grid system was developed to study the expansion of a plasma cloud in the F region and topside ionosphere. The model maintains an adequate resolution for the released cloud motion and its interaction with the immediate environment, and it includes the effect due to the coupling with the distant part of the ionosphere (i.e., E region). Simulations were performed using realistic background ionospheric density profiles in both the E and F regions. The results show that the cloud coupling to the underlying E region affects the perpendicular cloud motion the most. The distant coupling acts to reduce the perturbation potential and perpendicular velocity and delays or eliminates the striations. These simulation results are consistent with simple analytical approximations. The simulation results also show that the distant coupling has a very small effect on 'localized' phenomena, such as the cloud expansion along the B RIGHT ARROW field and the electrostatic snowplow. The cloud-induced electric potential is attenuated in the lower E region. The electrons flow along the B RIGHT ARROW field, carrying the current to the E region and back to the cloud. The current closure is demonstrated in three dimensions for the first time for such a problem. The perpendicular current flowing through the plasma cloud is closed by the field-aligned electron current and the background perpendicular (mainly Pedersen) current in both the E and F regions. The 'image cloud' formation in t he E region is also clearly demonstrated. The variation of the density change in the 'image cloud' along the B RIGHT ARROW field and the features of the image cloud are shown.

  10. Probing the Mysteries of Io's Ionosphere With the Plasma Instrumentation on the Galileo Spacecraft

    NASA Astrophysics Data System (ADS)

    Frank, L. A.; Paterson, W. R.

    2001-12-01

    At the time of writing this abstract the measurements during the close flyby of Jupiter's moon Io had been just acquired with the Galileo recorder for subsequent transmission to Earth at much lesser telemetry rates. This flyby near Io's northern pole on August 6, 2001 and a future flyby near the southern pole on the following October 16 will provide the plasma measurements for this presentation. These in-situ observations of Io are expected to provide further insight into the nature of its ionosphere and the accompanying currents and charged particle acceleration. Surprises can be expected from these flybys. For example, the flyby with closest approach at 208 km on February 22, 2000 provided a direct passage through the thermal ions at the top of the ionosphere. A cool plasma was encountered with temperatures of about 2300 K, and in the range of the hotter temperatures for some volcanic plumes as recorded remotely with other Galileo instruments. The observations from the flybys in August and October at closest approaches of 200 km and 181 km, respectively, are eagerly awaited.

  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 checked for the fraction of electron spectra having features typical of the magnetosheath and magnetic pileup region, such as differential energy flux intensity at energies >50 eV. The results are a classification of the oblique echoes into: solar wind only, no solar wind and mixing of both, which we can use to characterize the generation of ionospheric bulges.

  12. 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.

  13. Theory and Observations of Plasma Waves Excited Space Shuttle OMS Burns in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Pfaff, R. F.; Schuck, P. W.; Hunton, D. E.; Hairston, M. R.

    2010-12-01

    Measurements of artificial plasma turbulence were obtained during two Shuttle Exhaust Ionospheric Turbulence Experiments (SEITE) conducted during the flights of the Space Shuttle (STS-127 and STS-129). Based on computer modeling at the NRL PPD and Laboratory for Computational Physics & Fluid Dynamics (LCP), two dedicated burns of the Space Shuttle Orbital Maneuver Subsystem (OMS) engines were scheduled to produce 200 to 240 kg exhaust clouds that passed over the Air Force Research Laboratory (AFRL) Communications, Navigation, and Outage Forecast System (C/NOFS) satellite. This operation required the coordination by the DoD Space Test Program (STP), the NASA Flight Dynamics Officer (FDO), the C/NOFS payload operations, and the C/NOFS instrument principal investigators. The first SEITE mission used exhaust from a 12 Second OMS burn to deposit 1 Giga-Joules of energy into the upper atmosphere at a range of 230 km from C/NOFS. The burn was timed so C/NOFS could fly though the center of the exhaust cloud at a range of 87 km above the orbit of the Space Shuttle. The first SEITE experiment is important because is provided plume detection by ionospheric plasma and electric field probes for direct sampling of irregularities that can scatter radar signals. Three types of waves were detected by C/NOFS during and after the first SEITE burn. With the ignition and termination of the pair of OMS engines, whistler mode signals were recorded at C/NOFS. Six seconds after ignition, a large amplitude electromagnetic pulse reached the satellite. This has been identified as a fast magnetosonic wave propagating across magnetic field lines to reach the electric field (VEFI) sensors on the satellite. Thirty seconds after the burn, the exhaust cloud reach C/NOFS and engulfed the satellite providing very strong electric field turbulence along with enhancements in electron and ion densities. Kinetic modeling has been used to track the electric field turbulence to an unstable velocity distribution produced after the supersonic exhaust molecules charge exchanged with ambient oxygen ions. Based on the success of the first SEITE mission, a second dedicated burn of the OMS engine was scheduled to intercept the C/NOFS satellite, this time at an initial range of 430 km. The trajectory of this exhaust cloud was not centered on the satellite so the turbulent edge was sampled by the C/NOFS instruments. The electromagnetic pulse and the in situ plasma turbulence was recorded during the second SEITE experiment. A comparison of the data from the two OMS burns shows that a wide range of plasma waves are consistently produced with rocket engines are fired in the ionosphere.

  14. Asymmetric Ionospheric Outflow Observed at the Dayside Magnetopause

    NASA Astrophysics Data System (ADS)

    Lee, S. H.; Zhang, H.; Zong, Q.; Sibeck, D. G.; Wang, Y.; Glassmeier, K. H.; Reme, H.

    2014-12-01

    An important source of the terrestrial magnetospheric plasma is cold plasma from the polar ionosphere. The ionospheric ion outflows have been rarely observed at the dayside magnetopause. We investigate the source and the behaviors of the cold ions observed by the Cluster spacecraft measurements. The pitch angle distributions (0°-75°) of the cold ions observed by both C1 and C3 at the dayside magnetopause indicate that these cold ions are ionospheric outflows coming from the southern hemisphere. The cold ions (< 200 eV) fluxes are modulated by the ULF wave electric field. The cold ions move perpendicular to the magnetic field due to the enhanced convection electric field when they are close to the magnetic reconnection region. Two different populations (possibly H+ and He+) were observed in the magnetosphere. Our results suggest that the ionospheric outflows can be transported to the dayside magnetopause and may play an important role in the dynamics of this region.

  15. Maintenance of the Venus nightside ionosphere: Electron precipitation and plasma transport

    SciTech Connect

    Spenner, K.; Knudsen, W.C.; Whitten, R.C.; Michelson, P.F.; Miller, K.L.; Novak, V.

    1981-10-01

    Suprathermal integral electron spectra between 5 and 45 eV measured by the Pioneer Venus orbiter RPA are presented for the Venus nightside ionosphere. The observed integral electron flux is relatively constant with time and altitude. The simultaneously measured plasma density is much more variable and not correlated with the electron flux. For a typical electron spectrum the ionization rates and the ion density height profiles for O/sup +/ and O/sub 2//sup +/ are calculated for 10 and 90/sup 0/ magnetic dip angle. The O/sup +/ and O/sub 2//sup +/ ion density height profiles are also calculated for a downward flux of O/sup +/ ions at 10, 30, and 90/sup 0/ magnetic dip angle. Comparison of the numerical modeling results with median profiles of O/sup +/ and O/sub 2//sup +/ ions measured by the RPA reveals that a downward flux of O/sup +/ ions of between 1 and 2 x 10/sup 8/ cm/sup -2/ s/sup -1/ satisfactorily reproduces both the O/sup +/ and O/sub 2//sup +/ measured median nightside density profiles. The typical suprathermal electron spectrum produces an O/sub 2//sup +/ profile which is about an order of magnitude too small. From the evidence presented in this paper, from previous measurements of adequate O/sup +/ transport across the Venus terminator, and from interpretation of ion thermal measurements, we conclude that transport of O/sup +/ ions from the dayside ionosphere is responsible for most of the ionization rate required to maintain the nightside ionsophere. Variation in the O/sup +/ transport mechanism is primarily responsible for the large variation of the nightside ionosphere density. Suprathermal electrons provide a relatively constant ionization rate which is of the order of one fourth that of O/sup +/ transport and which contributes principally to the O/sub 2//sup +/ peak.

  16. Convection in planetary magnetospheres

    NASA Astrophysics Data System (ADS)

    Hill, T. W.

    Magnetospheric convection is a system of bulk motion of magnetospheric flux tubes, powered either internally by an unstable distribution of plasma produced therein, or externally by coupling to the motion of an adjacent medium. Internally powered convection results from one of three types of magnetospheric interchange instability: the flute instability associated with a plasma pressure distribution containing excess internal energy of compression; the Rayleigh-Taylor instability deriving from a plasma mass distribution containing excess gravitational potential energy; and the centrifugal instability which is the inverse of the Rayleigh-Taylor instability, occurring outside the synchronous orbit radius. The centrifugal instability is primarily responsible for convection in the magnetosphere of Jupiter, and probably also that of Saturn. Externally powered convection may be driven either by atmospheric winds, coupled to the magnetosphere by ionospheric Pedersen currents, or by the solar wind, coupled to the magnetosphere by one or more collisionless momentum transfer processes. The solar wind is the primary driver of convection in earth's magnetosphere, and the primary coupling mechanism is interconnection between the geomagnetic and interplanetary magnetic fields. For the magnetosphere of Uranus (if it exists), a disc dynamo interaction has been proposed that is powered by a direct coupling between thg flow of the solar wind and the rotation of the planet.

  17. Plasma flux and gravity waves in the midlatitude ionosphere during the solar eclipse of 20 May 2012

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Wu, Chen; Huang, Xueqin; Zhao, Zhengyu; Zhong, Dingkun; Qi, Hao; Huang, Liang; Qiao, Lei; Wang, Jin

    2015-04-01

    The solar eclipse effects on the ionosphere are very complex. Except for the ionization decay due to the decrease of the photochemical process, the couplings of matter and energy between the ionosphere and the regions above and below will introduce much more disturbances. Five ionosondes in the Northeast Asia were used to record the midlatitude ionospheric responses to the solar eclipse of 20 May 2012. The latitude dependence of the eclipse lag was studied first. The foF2 response to the eclipse became slower with increased latitude. The response of the ionosphere at the different latitudes with the same eclipse obscuration differed from each other greatly. The plasma flux from the protonsphere was possibly produced by the rapid temperature drop in the lunar shadow to make up the ionization loss. The greater downward plasma flux was generated at higher latitude with larger dip angle and delayed the ionospheric response later. The waves in the foEs and the plasma frequency at the fixed height in the F layer are studied by the time period analytic method. The gravity waves of 43-51 min center period during and after the solar eclipse were found over Jeju and I-Cheon. The northward group velocity component of the gravity waves was estimated as ~108.7 m/s. The vertical group velocities between 100 and 150 km height over the two stations were calculated as ~5 and ~4.3 m/s upward respectively, indicating that the eclipse-induced gravity waves propagated from below the ionosphere.

  18. 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.

  19. International Reference Ionosphere: Past, present, and future. I - Electron density. II - Plasma temperatures, ion composition and ion drift

    NASA Technical Reports Server (NTRS)

    Bilitza, D.; Rawer, D.; Bossy, L.; Guliaeva, T.

    1993-01-01

    The most important investigations leading to the International Reference Ionosphere 1990 (IRI-90) are overviewed, and the latest version of the model is described. The shortcomings and limitations of the IRI-90 are pointed out, together with the ways of overcoming them. The list of studies that the IRI group has yet to carry out includes the investigations of magnetic storm effects as the highest priority. This paper discusses determinations of and the available data on the electron density, plasma temperatures, ion composition, and ion drift in the ionosphere, together with future improvements needed on these parameters.

  20. 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 than those obtained with the simplest MHD description.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Modeling polar cap F-region patches using time varying convection

    NASA Technical Reports Server (NTRS)

    Sojka, J. J.; Bowline, M. D.; Schunk, R. W.; Decker, D. T.; Valladares, C. E.; Sheehan, R.; Anderson, D. N.; Heelis, R. A.

    1993-01-01

    Creation of polar cap F-region patches are simulated for the first time using two independent physical models of the high latitude ionosphere. The patch formation is achieved by temporally varying the magnetospheric electric field (ionospheric convection) input to the models. The imposed convection variations are comparable to changes in the convection that result from changes in the B(y) IMF component for southward IMF. Solar maximum-winter simulations show that simple changes in the convection pattern lead to significant changes in the polar cap plasma structuring. Specifically, in winter, as enhanced dayside plasma convects into the polar cap to form the classic tongue-of-ionization the convection changes produce density structures that are indistinguishable from the observed patches.

  6. Theoretical study on plasma wind and convection in Jovian magnetodisc

    NASA Astrophysics Data System (ADS)

    Oya, H.; Aoyama, T.

    An outflow plasma model in the closed magnetic field configuration of the Jovian magnetodisk region is theoretically investigated. The plasma behavior is analyzed for a simple case of an aligned rotator model where the axis of the magnetic dipole coincides with the rotation axis of Jupiter. The results indicate that the plasma is flowing out due to the centrifugal force forming the disk wind that blows outward with supermagnetosonic velocity when the plasma approaches a critical region. The disk current expands as a result of the plasma outflow. The magnetic field is frozen in the flowing plasma in the disk plasma region; a transient region separates the magnetic lobe of the Jovian magnetosphere from the flowing disk plasma. The position of the magnetopause is compressed due to heating effects in the disk plasma when the solar wind pressure increases. The plasma flow then cannot exceed the magnetosonic velocity, and no disk wind is formed.

  7. A Traveling Convection Vortex Event Study: Instantaneous Ionospheric Equivalent Currents, Estimation of Field-aligned Currents, and The Role of Induced Currents

    NASA Astrophysics Data System (ADS)

    Amm, O.; Engebretson, M. J.; Hughes, T.; Newitt, L.; Viljanen, A.; Watermann, J.

    We analyse a traveling convection vortex (TCV) event on January 31, 1997, using ground magnetometer data of the CANOPUS, MACCS, Geological Survey of Canada, Greenland, and IMAGE networks. For the first time, spatial and instantaneous distri- butions of the ionospheric equivalent currents associated with a TCV are obtained. We apply the method of spherical elementary currents (SECS) to calculate these currents, as well as to infer the part of the ground magnetic signatures that is caused by internal currents induced into the Earth. While the ratio between the internally generated and the total horizontal ground magnetic field is in most part of the analysis area around 10-25%, in some regions it can reach values of 50% and larger. Using the assump- tion of a uniform Hall to Pedersen conductance ratio, and that conductance gradients perpendicular to the ionospheric electric field are vanishing, we can estimate the total field-aligned current (FAC) associated with the two vortices of the TCV in our analy- sis area. It amounts to~380 kA for the downward FAC in the western vortex, and to~ 315 kA for the upward current in the eastern vortex, part of which extends to outside of the analysis area.

  8. Space Shuttle Exhaust Modifications of the Mid-Latitude Ionospheric Plasma As Diagnosed By Ground Based Radar

    NASA Astrophysics Data System (ADS)

    Lind, F. D.; Erickson, P. J.; Bhatt, A.; Bernhardt, P. A.

    2009-12-01

    The Space Shuttle's Orbital Maneuvering System (OMS) engines have been used since the early days of the STS program for active ionospheric modification experiments designed to be viewed by ground based ionospheric radar systems. In 1995, the Naval Research Laboratory initiated the Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) Program using dedicated Space Shuttle OMS burns scheduled through the US Department of Defense's Space Test Program. SIMPLEX objectives include generation of localized ion-acoustic turbulence and the formation of ionospheric density irregularities for injections perpendicular to the local magnetic field, creating structures which can scatter incident UHF radar signals. We discuss radar observations made during several recent SIMPLEX mid-latitude experiments conducted over the Millstone Hill incoherent scatter radar system in Westford, Massachusetts. OMS engine firings release 10 kg/s of CO2, H2, H2O, and N2 molecules which charge exchange with ambient O+ ions in the F region, producing molecular ions and long lived electron density depletions as recombination occurs with ambient electrons. Depending on the magnetic field angle, the high velocity of the injected reactive exhaust molecules relative to the background ionosphere can create longitudinal propagating ion acoustic waves with amplitudes well above normal thermal levels and stimulate a wide variety of plasma instability processes. These effects produce high radar cross section targets readily visible to the Millstone Hill system, a high power large aperture radar designed to measure very weak scatter from the quiescent background ionosphere. We will survey the plasma instability parameter space explored to date and discuss plans for future SIMPLEX observations.

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

    SciTech Connect

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

    1989-06-01

    An electron beam was injected into Earth's ionosphere on August 1, 1985, the flight of the space shuttle /ital 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 ascoustic instability to provide a returning flux of hot electorns by means of quasi-linear diffusion. /copyright/ American Geophysical Union 1989

  10. Dynamics of plasma density perturbations in the upper ionosphere and the magnetosphere under the action of powerful HF radio waves

    NASA Astrophysics Data System (ADS)

    Borisov, N.; Ryabova, N.; Ruzhin, Yu.

    2015-11-01

    Dynamics of the density perturbations of the main plasma components (electrons, oxygen and hydrogen ions) in the upper ionosphere and the magnetosphere under the action of powerful HF radio waves is discussed theoretically and numerically. For finite heating pulse and different effective powers the variations of the density perturbations in time at various heights are investigated. We argue that due to collisionless damping the magnetospheric duct along the whole field line is not formed. Instead positive and negative perturbations of the main plasma components propagating with the attenuation in the magnetosphere with two different speeds are predicted. Utilization of pulsed heating provides significant information concerning plasma perturbations in the upper ionosphere and the magnetosphere.

  11. 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.

  12. 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.

  13. Mechanisms of Ionospheric Mass Ejection

    NASA Technical Reports Server (NTRS)

    Moore, Thomas Earle; Khazanov, George V.; Hannah, Mei-Ching; Glocer, Alex

    2010-01-01

    Ionospheric outflows are directly responsive to solar wind disturbances, particularly in the dayside auroral cusp or cleft regions. Inputs of both electromagnetic energy (Poynting flux) and kinetic energy (particle precipitation) are closely correlated with these outflows. We assess the importance of processes thought to drive ionospheric outflows. 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 precipitation particles. Solar wind energy dissipation 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 and neutral gas. 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 multi-species global simulation codes. We conclude by assessing outstanding obstacles to this objective.

  14. A global climatology for equatorial plasma bubbles in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Gentile, L. C.; Burke, W. J.; Rich, F. J.

    2006-03-01

    We have developed a global climatology of equatorial plasma bubble (EPB) occurrence based on evening sector plasma density measurements from polar-orbiting Defense Meteorological Satellite Program (DMSP) spacecraft during 1989-2004. EPBs are irregular plasma density depletions in the post-sunset ionosphere that degrade communication and navigation signals. More than 14400 EPBs were identified in ~134000 DMSP orbits. DMSP observations basically agree with Tsunoda's (1985) hypothesis that EPB rates peak when the terminator is aligned with the Earth's magnetic field, but there are also unpredicted offsets in many longitude sectors. We present an updated climatology for the full database from 1989-2004 along with new plots for specific phases of the solar cycle: maximum 1989-1992 and 1999-2002, minimum 1994-1997, and transition years 1993, 1998, and 2003. As expected, there are significant differences between the climatologies for solar maximum and minimum and between the two solar maximum phases as well. We also compare DMSP F12, F14, F15, and F16 observations at slightly different local times during 2000-2004 to examine local time effects on EPB rates. The global climatologies developed using the DMSP EPB database provide an environmental context for the long-range prediction tools under development for the Communication/Navigation Outage Forecasting System (C/NOFS) mission.

  15. Peculiarities of Excitation of Large-Scale Plasma Density Irregularities During Modification of the Ionospheric F 2 Region by High-Power HF Radio Waves

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Schorokhova, E. A.; Kunitsyn, V. E.; Andreeva, E. S.; Padokhin, A. M.

    2016-03-01

    We present the experimental results concerning the features of large-scale artificial plasma-density irregularities excited in the ionospheric F2 region by high-power HF radio waves. The experiments were performed in recent years using the SURA heating facility. It is shown that at the altitude of the pump-wave reflection, these irregularities are most efficiently generated in the magnetic zenith region. The effect of enhancement of the large-scale irregularity generation at the edge of the pump-wave beam is revealed. The results of studying large-scale irregularities recorded at the altitudes of the topside ionosphere are presented. Experimental results concerning the features of the internal gravity waves generated at the ionospheric altitudes during periodic heating of the ionospheric plasma by high-power HF radio waves are summarized and their possible influence on generation of artificial ionospheric irregularities at a long distance from the heater is discussed.

  16. Convective stimulated Brillouin scattering of obliquely incident laser light in laser plasmas

    SciTech Connect

    Gupta, G.P.; Sinha, B.K.

    1997-07-01

    Convective stimulated Brillouin scattering (SBS) in the directly backward direction of the obliquely incident laser light in an expanding and inhomogeneous laser plasma is studied. Accounting for the thermal motion of both electrons and ions of the plasma in the dispersion relation of the ion-acoustic wave, the expression of the convective SBS gain coefficient is derived in the weak coupling limit. The behavior of the gain with the angle of incidence of the laser irradiation in a laser-produced CH plasma is investigated by considering various plasma and laser conditions in light of the reported laser-plasma experiment with the 0.35 {mu}m laser irradiating the CH target. The results are observed to be significantly different from those for normal incidence. {copyright} {ital 1997 American Institute of Physics.}

  17. Some new features of ionospheric plasma depletions over the Indian zone using all sky optical imaging

    NASA Astrophysics Data System (ADS)

    Sinha, H. S. S.; Raizada, S.

    2000-08-01

    An all sky optical imaging system was operated from Sriharikota rocket range (SHAR) (14° N, 80° E, 5.5° N dip latitude) during January-March, 1993 to observe ionospheric plasma depletions through 630 nm and 777.4 nm night glow emissions. Strong plasma depletions were observed only on four nights viz., 14, 17, 19 and 21 February, 1993. Except the 17 February, which was a magnetically disturbed day, all the other nights pertained to magnetically quiet period. A number of plasma depletion parameters such as, degree of depletion, east-west extent, tilt with respect to the geomagnetic field, inter-depletion distance, drift velocity and plasma enhancements or brightness patterns were estimated. Some of the important results are: (a) It was found that the east-west extent of plasma depletions varied with the degree of depletion; for the 630 nm images the degree of depletion ranged between 6-9% per 100 km east-west extent and for 777.4 nm images it was 3% per 100 km east-west extent, (b) The average inter-depletion distance (IDD) was in the range of 1500±100 km during the magnetically disturbed period and 740±60 km during quiet periods. This is suggestive of gravity wave modulation of the bottom side of the F-region. While the large scale gravity waves (1500±100 km) of auroral origin could be responsible during magnetically disturbed period, smaller scale gravity waves (740±60 km) having their origin in the lower atmosphere could produce initial perturbation in the bottom side of the F-region, (c) Plasma depletions are observed to have an eastward tilt in the range of 10-15° with respect to the geomagnetic field. It has been suggested here that these tilts are associated with the variation of plasma drift with altitude, (d) plasma depletions are observed to be moving eastwards with drift velocities in the range of 40-190 ms-1, and (e) Strong plasma enhancements or brightness patterns were observed on three nights. The degree of enhancement was by a factor of 1.4-3.8. These enhancements lasted for more than 15 minutes. Although, prima facie, these observations look similar to the transient brightness wave reported by Mendillo et al. (1997a), the high degree of enhancement and an extended duration of more than 15 minutes, observed in the present case, need to be understood.

  18. A traveling convection vortex event study: Instantaneous ionospheric equivalent currents, estimation of field-aligned currents, and the role of induced currents

    NASA Astrophysics Data System (ADS)

    Amm, O.; Engebretson, M. J.; Hughes, T.; Newitt, L.; Viljanen, A.; Watermann, J.

    2002-11-01

    We analyze a traveling convection vortex (TCV) event on 31 January 1997 using ground magnetometer data of the CANOPUS, MACCS, Geological Survey of Canada, Greenland, and IMAGE networks. For the first time, spatial and instantaneous distributions of the mesoscale ionospheric equivalent currents associated with a TCV are obtained. We apply the method of spherical elementary currents (SECS) to calculate these currents, as well as to infer the part of the ground magnetic signatures that is caused by internal currents induced in the Earth. The resulting ionospheric equivalent currents consist of a leading clockwise vortex centered at 71° CGM latitude which moves westward with ˜7.3 km s-1 and a trailing anticlockwise vortex at 77 ° latitude which moves southwestward away from noon at ˜3.0 km s-1. In an area of ˜200 km around the center of the twin vortices the derived equivalent current densities are less than 70 mA m-1 but reach 100-160 mA m-1 in a broad channel of equatorward currents between the vortices. Using the assumption of a uniform Hall to Pedersen conductance ratio and the assumption that conductance gradients perpendicular to the ionospheric electric field are vanishing, we can estimate the field-aligned current (FAC) associated with the TCV. The maxima of ˜1 μA m-2 of downward FAC in the leading western vortex, and of ˜0.4 μA m-2 of upward FAC in the trailing eastern vortex occur along the perimeter of the vortices, not in their centers, in contrast to the prediction of ionosphere-magnetosphere coupling theories for TCVs. The integrated FAC are not fully balanced between the two vortices but show an excess of downward FAC. While the ratio between the internally generated and the total horizontal ground magnetic field for most magnetometer sites in the TCV area amounts to around 20-40%, at some stations it can reach values of 50% and larger.

  19. Effect of the deformation of a regular ionospheric plasma profile on the anomalous absorption of a high-power radio wave in the resonance region

    NASA Astrophysics Data System (ADS)

    Vas'kov, V. V.; Dimant, Ia. S.

    1989-06-01

    It is shown that localized distortions of ionospheric plasma density profile due to the intense excitation of plasma oscillations near the upper-hybrid resonance of a high-power radio wave can lead to a change in the anomalous absorption of the disturbing wave. The profile deformation stabilizes the amplitude of a high-power radio wave reflected from the ionosphere and leads to an asymmetry in sounding waves with frequencies above and below that of the high-power wave.

  20. Ionosphere plasma electron parameters from radio frequency sweeping impedance probe measurements

    NASA Astrophysics Data System (ADS)

    Spencer, E.; Patra, S.

    2015-09-01

    In this work we will describe the technique of using an RF sweeping impedance probe (SIP) to measure the AC impedance of an electrically short monopole immersed in a plasma. We analyze the SIP measurements which are taken from the payload of the Storms sounding rocket, launched from Wallops Island, Virginia, in 2007. The scientific objective of the Storms mission was to concentrate on whether density irregularities observed in midlatitude spread F could arise from ionospheric coupling to terrestrial weather. As such, independent measurements of the electron density profile are crucial. Since the inherent nature of the SIP technique makes it relatively insensitive to errors introduced through spacecraft charging, probe contamination, and other DC effects, it is an ideal instrument to employ under disturbed plasma conditions. The instrument measures both the magnitude and phase of the AC impedance from 100 kHz to 20 MHz in 128 frequency steps, performing 45,776 sweeps over the entire flight. From these measurements we infer both the absolute electron density ne and the electron neutral collision frequencies νen throughout the flight trajectory. The SIP data can be approximately analyzed using a fluid formulation and thin sheath approximation particularly at altitudes below 200 km, which allows us to match the measurements to quasi-static analytical formulas. At about 265 km on the upleg, the magnitude data transitioned to a highly damped response with increasing altitude. The phase data, on the other hand, continued to indicate increased plasma density and reduced collisionality as expected. For a large portion of the flight, the payload of the Storms mission exhibited an uncontrolled coning motion, making the local magnetic field orientation with respect to the dipole difficult to decipher. Despite these difficulties, we were able to obtain robust estimates of the electron density profile, using the phase information from each sweep. In addition, the electron neutral collision frequency obtained from matching to phase data alone was on the correct order of magnitude with respect to Naval Research Laboratory Mass Spectrometer Incoherent Scatter-Extended model values in the ionosphere between 100 km and 150 km.

  1. Microsatellite missions to conduct midlatitude studies of equatorial ionospheric plasma bubbles

    NASA Astrophysics Data System (ADS)

    Krause, L. Habash; Enloe, C. L.; Haaland, R. K.; Golando, P.

    Two missions presently under development by the United States Air Force Academy (USAFA), FalconSAT-2 and FalconSAT-3, include mission scientific objectives targeting the study of ionospheric F region plasma density depletions and topside bubbles associated with the so-called Equatorial Spread F (ESF) phenomena. The Miniature Electrostatic Analyzer (MESA), a USAFA-designed patch sensor that measures differential energy fluxes of electrons from 0.05 to 13 eV in six channels, is the primary experiment aboard FalconSAT-2, a 25-kg microsatellite intended for launch into an International Space Station (ISS) orbit via the Space Shuttle. Because the orbit will be approximately 360 km in altitude and of 52° inclination, FalconSAT-2 observations will complement those of low latitude missions (e.g., C/NOFS) and polar latitude, higher altitude missions (e.g., DMSP). Realistic internal magnetic field models demonstrate that field lines with apex heights of 1500 km (representing the upper altitude limit of equatorial plasma bubbles) may intersect the orbit plane at dip latitudes greater than 35°. Thus, FalconSAT-2 will be able to observe plasma depletions that have propagated poleward along the field lines and lower in altitude, depletions that may not be observed with the high altitude DMSP and the low latitude C/NOFS. Additionally, there may be opportunities for FalconSAT-2 to make simultaneous multipoint in situ measurements of large-scale plasma bubbles with other low altitude satellites, such as C/NOFS and DMSP. We will present a statistical analysis of the probability of making such measurements using nominal orbital parameters of the relevant spacecraft. Finally, a description of the FalconSAT-3 follow-on mission, including scientific objectives associated with seeking kinetic effects, is presented.

  2. Collisional/resonance absorption in cold/warm magnetized plasmas of the F-region high-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Gondarenko, N. A.; Ossakow, S. L.; Bernhardt, P. A.

    2009-05-01

    The collisional/resonance absorption due to linear mode conversion of electromagnetic waves into electrostatic/plasma waves is studied in cold/warm magnetized plasmas relevant to the F-region of the high-latitude ionosphere. The absorption coefficient is calculated numerically using a full-wave model for high-frequency waves incident normally/obliquely to the direction of inhomogeneity. The absorption coefficient of collisional cold plasmas is found to be independent of the collision frequency in the small range of incidence angles near the critical angle; whereas, outside this range absorption increases with increasing collisions. In warm collisionless plasmas, the resonance absorption coefficient is shown to be independent of the electron temperature values pertinent to the F-region plasma. We have demonstrated for the first time a strong effect of the external magnetic field arbitrarily oriented in the plane of incidence on the absorption coefficient, which is not pronounced in the limit of weakly magnetized plasmas.

  3. Radar probing of ionospheric plasmas precisely confirms linear kinetic plasma theory (Hannes Alfvén Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Farley, Donald

    2010-05-01

    In 1958 W. E. Gordon first suggested that huge radars could probe the ionosphere via scattering from independent electrons, even though the radar cross section of a single electron is only 10-28 m2. This suggestion quickly led to the construction of two enormous radars in the early 1960s, one near Lima, Peru, and one near Arecibo, Puerto Rico. It soon became apparent that the theory of this scatter was more complicated than originally envisaged by Gordon. Although the new theory was more complicated, it was much richer: by measuring the detailed shape of the Doppler frequency spectrum (or alternatively the signal autocorrelation function, the ACF), a radar researcher could determine many, if not most, of the parameters of interest of the plasma. There is now a substantial network of major radar facilities scattered from the magnetic equator (Peru) to the high arctic latitudes (Svalbard and Resolute Bay), all doing important ionospheric research. The history of what is now called Incoherent Scatter (even though it is not truly incoherent) is fascinating, and I will touch on a few highlights. The sophisticated radar and data processing techniques that have been developed are also impressive. In this talk, however, I want to focus mainly on the details of the theory and on how the radar observations have confirmed the predictions of classical linear plasma kinetic theory to an amazingly high degree of precision, far higher than has any other technique that I am aware of. The theory can be, and has been, developed from two very different points of view. One starts with 'dressed particles,' or Coulomb 'clouds' around ions and electrons moving with a Maxwellian velocity distribution; the second starts by considering all the charged particles to be made up of a spectrum of density plane waves and then invokes a generalized version of the Nyquist Noise Theorem to calculate the thermal amplitudes of the waves. Both approaches give exactly the same results, results that allow us to predict exactly the scattered power and Doppler spectrum for any given set of plasma parameters (e.g., electron and ion temperatures, ionic composition, mean drifts and currents, the geomagnetic field, and particle collisions). So far, these predictions have not failed, although in recent years we have had to resort to numerical simulations to do a proper calculation of electron Coulomb collisions when the radar beam is pointed very nearly perpendicular to the magnetic field. This is because no analytic way has yet been found to properly apply the Fokker-Planck Coulomb collision model to the scattering process. Of course the theory predicts the spectrum, given all the plasma parameters, when what we really want to do in ionospheric research is the inverse, namely find the parameters, given the radar data. This inverse process can be quite difficult to do optimally if there are too many unknown parameters. Statistical inverse theory can require enormous computing power, but progress is being made.

  4. Statistical investigation of the noise added to a model of the effect of solar activities on the plasma of the ionosphere using DEMETER satellite data

    NASA Astrophysics Data System (ADS)

    Sharzehei, Mahmoud; Masnadi-Shirazi, M. A.; Golbahar-Haghighi, Sh.

    2015-08-01

    Although a relation between ionospheric anomalies and occurrence of strong earthquake has been studied for several decades, the issue of finding anomalies in ionospheric parameter before earthquakes has been always a matter of controversy among scientific community. In this way, the study of the ionosphere by satellite observers plays a significant role in assessing the feasibility of finding anomalies in ionospheric parameters as short-term precursors of earthquakes. Regardless of whether this assertion about ionospheric precursor is true or false, the ionosphere has been shown to be affected more by solar activities than other events such as seismic activities; thus, the modeling of ionospheric variation caused by solar activities is valuable in assessing the possibility of ionospheric precursors. One of the most famous satellites launched to investigate the ionospheric plasma perturbation associated with solar and seismic activities is the DEMETER, the French micro-satellite. To carry on such investigation, one of its payloads, the onboard IAP experiment, allows for the measurement of important plasma parameters including ion composition densities and their temperature. The current work presents a statistical distribution for the noise added to the proposed model describing the regular effect of solar activities on the ionospheric plasma above Iran during one half-orbit time of the DEMETER (~35 min) in the absence of an earthquake and a quiet time condition. The results of this study show that the proposed modeling noise statistically agrees with the Gaussian distribution; however, its variance may vary from one day to another. In other words, the noise is a non-stationary random process. The proposed model is then evaluated by a set of experimental data. The results of this evaluation show that the measured data follow the proposed model.

  5. 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.

  6. Experimental evidence of low-dimensional chaotic convection dynamics in a toroidal magnetized plasma.

    PubMed

    Zivković, T; Rypdal, K

    2008-03-01

    In a toroidal plasma confined by a purely toroidal magnetic field with a weak vertical field superimposed a system of convection cells are generated spontaneously, interacting with a background electron density gradient. The dynamics of this interaction is low-dimensional, chaotic, and consistent with solutions of the Lorenz equations in the diffusionless limit. PMID:18517566

  7. Numerical modeling of the polar F region ionosphere taking into account the solar wind conditions

    NASA Astrophysics Data System (ADS)

    Uvarov, V. M.; Lukianova, R. Yu.

    2015-12-01

    The numerical model predicts the 3-D distribution of electron density over the high-latitude F region ionosphere in the altitudes between 130 and 600 km. The distinctive feature of the model is an analytical representation of the electric potential distribution over the high-latitude ionospheric shell which continuously evolving with the solar wind parameters, season and universal time. In this approach the convection electric field is directly related to the field-aligned currents of magnetospheric origin which are controlled by the solar wind. The time-dependent ion continuity and momentum equations are solved as a function of altitude within a convecting and corotating plasma flux tube. Modeling results show that the polar ionosphere F region responds strongly to the change in the IMF polarity and the solar zenith angle. Large-scale ionospheric irregularities are reproduced in details.

  8. 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.

  9. Divertor E X B Plasma Convection in DIII-D

    SciTech Connect

    Boedo, J.A.; Schaffer, M.J.; Maingi, M.; Lasnier, C.J.; Watkins, J.G.

    1999-07-01

    Extensive two-dimensional measurements of plasma potential in the DIII-D tokamak divertor region are reported for standard (ion VB{sub T} drift toward divertor X-point) and reversed B{sub T} directions; for low (L) and high (H) confinement modes; and for partially detached divertor mode. The data are consistent with recent computational modeling identifying E x B{sub T} circulation, due to potentials sustained by plasma gradients, as the main cause of divertor plasma sensitivity to B{sub T} direction.

  10. HF wave scattering by field-aligned plasma irregularities considering refraction in the ionosphere

    NASA Astrophysics Data System (ADS)

    Galushko, V. G.; Bezrodny, V. G.; Koloskov, A. V.; Paznukhov, V. V.; Reinisch, B. W.

    2013-03-01

    This paper analyzes the effect of ionospheric refraction on the scattering of high frequency (HF) signals by random field-aligned irregularities in the upper ionosphere. Ray optics calculations are made using the perturbation method for a plane-stratified (on average) ionosphere, i.e., the incident and scattered waves are both supposed to propagate along the undisturbed trajectories with neglect of the geomagnetic field effect. The equation for the so-called cone of aspect-sensitive scattering is derived to relate the trajectory characteristics of the incident and aspect-sensitive scattered signals. The Born approximation is applied to calculate the scattering cross-section for the anisotropic power law model spectrum of random irregularities of the upper ionosphere. The possibility of excitation of the ionospheric interlayer waveguide by the aspect-sensitive scattered HF signals is analyzed in detail for the specific conditions of the HF heating experiment at European Incoherent Scatter (EICSAT).

  11. Inductive-dynamic magnetosphere-ionosphere coupling via MHD waves

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    In the present study, we investigate magnetosphere-ionosphere/thermosphere (M-IT) coupling via MHD waves by numerically solving time-dependent continuity, momentum, and energy equations for ions and neutrals, together with Maxwell's equations (Ampère's and Faraday's laws) and with photochemistry included. This inductive-dynamic approach we use is fundamentally different from those in previous magnetosphere-ionosphere (M-I) coupling models: all MHD wave modes are retained, and energy and momentum exchange between waves and plasma are incorporated into the governing equations, allowing a self-consistent examination of dynamic M-I coupling. Simulations, using an implicit numerical scheme, of the 1-D ionosphere/thermosphere system responding to an imposed convection velocity at the top boundary are presented to show how magnetosphere and ionosphere are coupled through Alfvén waves during the transient stage when the IT system changes from one quasi steady state to another. Wave reflection from the low-altitude ionosphere plays an essential role, causing overshoots and oscillations of ionospheric perturbations, and the dynamical Hall effect is an inherent aspect of the M-I coupling. The simulations demonstrate that the ionosphere/thermosphere responds to magnetospheric driving forces as a damped oscillator.

  12. 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.

  13. Development of techniques for the use of DMSP (Defense Meteorology Satellite Program) SSIE (topside ionospheric plasma monitor) data in the AWS (Air Weather Service) 4D ionosphere model. Final report, 1 July 1984-20 April 1985

    SciTech Connect

    Secan, J.A.

    1985-04-20

    Techniques for improved use of topside-ionosphere observations within the Air Weather Service 4D ionosphere-model system are investigated. Topside observations are available at the Air Force Global Weather Central from the Topside Ionospheric Plasma Monitor (SSIE) on the Block 5D DMSP satellites. The investigations cover three study areas: 1) improvements to the topside ionospheric electron density profile model used within the 4D model, 2) improvements to the ionospheric data preprocessors in the 4D model system, and 3) improvements to the 4D model. Results are presented for tasks completed during the second year of the project. A parametrization of the topside electron density profile was developed based on a two component diffusive equilibrium representation of the ionosphere. This topside model can use the entire data set from the SSIE sensor to specify the profile or, if some data are unavailable, it will use an empirical model of the height 0(+) to H(+) transition height to construct the profile. A method was developed for generating grids of the 840km electron density from observations along an orbit track, and a computer program was written to test the method. This program was also used to investigate joint analyses of N sub e (840) and Total Electron Content observations.

  14. Development of techniques for the use of DMSP (Defense Meteorological Satellite Program) SSIE (Topside Ionospheric Plasma Monitor) data in the AWS (Air Weather Service) 4d ionosphere model. Technical report

    SciTech Connect

    Secan, J.A.

    1984-07-01

    Techniques for improved use of topside-ionosphere observations within the Air Weather Service (AWS) 4D ionosphere model system are investigated. Topside observations are available at the Air Force Global Weather Central (AFGWC) from the Topside Ionospheric Plasma Monitor (SSIE) on the Block 5D DMSP satellites. The investigations cover three study areas: 10 improvements to the topside ionospheric electron-density-profile model used within the 4D model, 2) improvements to the ionospheric-data preprocessors in the 4D model system, and 3) improvements to the 4D model. Results are presented for tasks completed and in progress. An evaluation of the topside parametrization used within the International Reference Ionosphere showed it inappropriate for use in the 4D model. This led to initial development of an alternative topside parametrization based on the O/sup +/ to H/sup +/ transition height. The current SSIE Ne (840) data preprocessor (program SSIELD) was evaluated and found to be deficient in several areas, so work was begun on developing improvements for this program. Improvements developed for the 4D model included definition of procedures to configure the model for a full global analysis and the development of procedures to construct 4D model height functions from sets of model electron density profiles.

  15. A multi-instrument case study of high-latitude ionospheric GNSS scintillation due to drifting plasma irregularities

    NASA Astrophysics Data System (ADS)

    van der Meeren, C.; Oksavik, K.; Moen, J. I.; Romano, V.

    2013-12-01

    For this study, GPS receiver scintillation and Total Electron Content (TEC) data from high-latitude locations on Svalbard have been combined with several other data sets, including the EISCAT Svalbard Radar (ESR) and allsky cameras, to perform a multi-instrument case study of high-latitude GPS ionospheric scintillations in relation to drifting plasma irregularities at night over Svalbard on 31 October 2011. Scintillations are rapid amplitude and phase fluctuations of electromagnetic signals. GNSS-based systems may be disturbed by ionospheric plasma irregularities and structures such as plasma patches (areas of enhanced electron density in the polar cap) and plasma gradients. When the GNSS radio signals propagate through such areas, in particular gradients, the signals experience scintillations that at best increases positioning errors and at worst may break the receiver's signal lock, potentially resulting in the GNSS receiver losing track of its position. Due to the importance of many GNSS applications, it is desirable to study the scintillation environment to understand the limitations of the GNSS systems. We find scintillation mainly localised to plasma gradients, with predominantly phase scintillation at the leading edge of patches and both phase and amplitude scintillation at the trailing edge. A single edge may also contain different scintillation types at different locations.

  16. 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 cannot fully explain the large temperatures before midnight nor the sudden decay near midnight.

  17. Ionosphere Electrodynamics and its Influence on the Main Ionospheric Trough and Equatorial Ionization Anomaly

    NASA Astrophysics Data System (ADS)

    Klimenko, M. V.; Klimenko, V. V.; Bryukhanov, V. V.

    2007-12-01

    In the given work the numerical simulation results of global distributions of the zonal current in the Earth's ionosphere and the critical frequency of the F2-layer of the ionosphere are presented. The calculations are executed with use of the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP) developed in West Department of IZMIRAN and added by the new block of calculation of the electric field of the dynamo and magnetospheric origin. The calculations are executed for quiet geomagnetic conditions during various seasons and levels of Solar activity without taking into account the electric field, and also with taking into account only dynamo-field or superposition of a dynamo-field and magnetospheric convection field with and without taking into account the shielding by field aligned currents of the second zone. It is shown, that the Main Ionospheric Trough is formed without taking into account the electric field as a result of joint action of processes of ionization, recombination and diffusion. The account of the dynamo-field alters this trough, and magnetospheric convection completes formation of the trough. Equatorial Ionization Anomaly is not formed in the absence of the electric field. The main part in formation of Equatorial Ionization Anomaly plays a dynamo-field. Zonal component of dynamo-field together with diffusion of thermal plasma along geomagnetic field lines under action of the pressure gradients in the Earth's gravity field cause a fountain effect at geomagnetic equator. Equatorial Electrojet is formed by the dynamo-field. Magnetospheric convection at presence of shielding weakly influences on behavior of Equatorial Electrojet. Without the shielding of magnetospheric convection electric field by Alfven layer electric field the magnetospheric convection influence on Equatorial Electrojet becomes stronger. It occurs during magnetospheric disturbances when the shielding is broken due to fast changes of the field aligned currents of the first zone. The Auroral Electrojet is formed mainly by magnetospheric convection electric field and depends on conditions of shielding and conductivity of a high-latitude ionosphere which depends on photoionization and ionization by fluxes of precipitating particles. There are presented the seasonal, Solar-cyclic and UT-variations of Equatorial and Auroral Electrojets, Main Ionospheric Trough and Equatorial Ionization Anomaly.

  18. 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.

  19. Convective Dust Clouds Driven by Thermal Creep in a Complex Plasma

    NASA Astrophysics Data System (ADS)

    Mitic, S.; Stterlin, R.; Hfner, 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.

  20. 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.

  1. A New Paradigm for Ionosphere-Thermosphere-Mesosphere Physics

    NASA Astrophysics Data System (ADS)

    Fuller-Rowell, Tim

    2015-04-01

    The ionosphere-thermosphere-mesosphere system is predominantly a neutral atmosphere domain with a fairly small fraction, less than 1%, that is ionized, similar in some ways to the chromosphere. Neutral dynamics and composition therefore play an important role in influencing and controlling the ionospheric plasma density and creating structure. Neutral thermospheric dynamics is driven from both above and below. Absorption of solar extreme ultraviolet radiation drives a global circulation, and magnetosphere/ionosphere plasma convection can accelerate neutral winds in excess of 1 km/s through collisions, and raise gas temperature by hundreds of degrees Kelvin by frictional dissipation. During extreme events these solar and magnetospheric sources dominate the ITM system, and understanding the plethora of physical processes that ensue has been the focus for more than 50 years. However, the bulk of solar energy reaching Earth penetrates well into the lower atmosphere and to the surface. Even if only a small fraction of this large energy reservoir can reach above 100 km it can have a significant impact on the ITM system and its variability. The main dynamic coupling and transfer of energy from below is largely through atmospheric waves, particularly tides (waves with harmonics of the 24 hour solar day), and gravity waves from the multitude of sources in the lower atmosphere. We now appreciate that dynamical changes and warmings in the stratosphere from changes in planetary wave activity can lead to a 50% change in electron content in the ionosphere, and which can actually be forecast days in advance. Tropospheric convection over continental landmass imprints a longitude structure on the ionosphere. Convective adjustment, extreme weather, wind shear, airflow over mountains, are some of the many sources of gravity waves activity that can grow in amplitude as they propagate into the thermosphere where they modulate and tilt the ionosphere. The ITM system is dynamic and variable even during apparently quiescent times, and understanding this new range of physical processes has created a new paradigm.

  2. Daytime ionospheric absorption features in the polar cap associated with poleward drifting F-region plasma patches

    NASA Astrophysics Data System (ADS)

    Nishino, M.; Nozawa, S.; Holtet, J. A.

    1998-02-01

    Absorption of radio waves in the polar ionosphere near the magnetic noon was observed on October 8, 1991, by the 30 MHz imaging riometer at Ny-Alesund, Svalbard (invariant latitude 76.1°). These observations showed that the initially widespread absorption features became localized and enhanced in the high-latitude sector of the field of view, and followed a poleward motion. This behavior occurred quasi-periodically and repeated every 10-20 min. Simultaneous observations by EISCAT "Polar" experiments showed that nine discrete plasma patches, with F-region electron density enhanced by an order of 106el/cm6, drifted poleward from the polar cusp to the cap during the same period. This coincidence suggested that the ionospheric absorption was associated with F-region plasma patches in the polar cap. Theoretical absorption values of 0.14 dB, estimated using the electron densities and the electron-ion collision frequencies from the EISCAT F-region plasma data, are smaller than the observed values (<0.8 dB). This discrepancy may be related to the difference between the theoretically- and experimentally-determined collision frequencies, as indicated by Wang et al. (1994). These localized, enhanced, and poleward drifting absorption features over Ny-Alesund may be explained as F-region plasma patches produced by a magnetosheath-like particle precipitation into the cusp, and as small-scale irregularities caused by density gradients of the patches drifting into the polar cap.

  3. In-situ studies of plasma irregularities in high latitude ionosphere with the ICI-2 sounding rocket within the 4DSpace project

    NASA Astrophysics Data System (ADS)

    Miloch, Wojciech; Moen, Joran; Spicher, Andres

    Ionospheric plasma is often characterized by irregularities, instabilities, and turbulence. Two regions of the ionospheric F-layer are of particular interest: low-latitudes for the equatorial anomaly and electrojet, and high-latitude regions where the most dynamic phenomena occur due to magnetic field lines coupling to the magnetosphere and the solar wind. The spectra of plasma fluctuations in the low-latitude F-layer usually exhibit a power law with a steeper slope at high frequencies [1]. Until recently, there was no clear evidence of the corresponding double slope spectra for plasma fluctuations in the high latitude ionospheric F-layer, and this difference was not well understood. We report the first direct observations of the double slope power spectra for plasma irregularities in the F-layer of the polar ionosphere [2]. The ICI-2 sounding rocket, which intersected enhanced plasma density regions with decameter scale irregularities in the cusp region, measured the electron density with unprecedented high resolution. This allowed for a detailed study of the plasma irregularities down to kinetic scales. Spectral analysis reveals double slope power spectra for regions of enhanced fluctuations associated mainly with density gradients, with the steepening of the spectra occurring close to the oxygen gyro-frequency. The double slope spectra are further supported by the results from the ICI-3 sounding rocket. Double slope spectra were not resolved in previous works presumably due to limited resolution of instruments. The study is a part of the 4DSpace initiative for integrated studies of the ionospheric plasma turbulence with multi-point, multi-scale in-situ studies by sounding rockets and satellites, and numerical and analytical models. A brief overview of the 4DSpace initiative is given. [1] M.C. Kelley, The Earth’s Ionosphere Plasma Physics and Electrodynamics (Elsevier, Amsterdam 2009). [2] A. Spicher, W. J. Miloch, and J. I. Moen, Geophys. Res. Lett. 40, (in press, accepted 13.02.2014).

  4. Observations of the relationship between ionospheric central polar cap and dayside throat convection velocities, and solar wind/IMF driving

    NASA Astrophysics Data System (ADS)

    Bristow, W. A.; Amata, E.; Spaleta, J.; Marcucci, M. F.

    2015-06-01

    Convection observations from the Southern Hemisphere Super Dual Auroral Radar Network are presented and examined for their relationship to solar wind and interplanetary magnetic field (IMF) conditions, restricted to periods of steady IMF. Analysis is concentrated on two specific regions, the central polar cap and the dayside throat region. An example time series is discussed in detail with specific examples of apparent direct control of the convection velocity by the solar wind driver. Closer examination, however, shows that there is variability in the flows that cannot be explained by the driving. Scatterplots and histograms of observations from all periods in the year 2013 that met the selection criteria are given and their dependence on solar wind driving is examined. It is found that on average the flow velocity depends on the square root of the rate of flux entry to the polar cap. It is also found that there is a large level of variability that is not strongly related to the solar wind driving.

  5. Ionospheric plasma flow over large high-voltage space platforms. I - Ion-plasma-time scale interactions of a plate at zero angle of attack. II - The formation and structure of plasma wake

    NASA Technical Reports Server (NTRS)

    Wang, J.; Hastings, D. E.

    1992-01-01

    The paper presents the theory and particle simulation results for the ionospheric plasma flow over a large high-voltage space platform at a zero angle of attack and at a large angle of attack. Emphasis is placed on the structures in the large, high-voltage regime and the transient plasma response on the ion-plasma time scale. Special consideration is given to the transient formation of the space-charge wake and its steady-state structure.

  6. Observation of GNSS signal perturbations due to HF heating induced plasma irregularities in the high latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Sato, Hiroatsu; Jakowski, Norbert; Rietveld, Michael; Borries, Claudia; Wilken, Volker

    Perturbations of the Total Electron Content (TEC) during HF heating experiments in the high latitude ionosphere are presented. Several experiments were carried out in December 2010 by the EISCAT heating facility in Ramsfjordbotn, Norway. Electromagnetic pumping waves were transmitted along the geomagnetic field lines with varying heating intervals. TEC has been derived for the experiment times, based on the measurements of two high rate dual frequency GNSS receivers placed in appropriate locations close to the facility. It has been previously reported that perturbations of GNSS signals can be found due to ionospheric plasma irregularities caused by high power radio waves. In the experiments presented here, HF ordinary mode beams were directed with elevation angle of 78 degrees in north-south plane transmitting at a frequency around 4 MHz. The center of the perturbed area in the F region ionosphere is estimated to be 41 km south of the facility. The heating and relaxation intervals varied between 10 and 180 seconds. EISCAT UHF radar measurements showed an enhancement of the electron temperature and electron density irregularity in the altitudes corresponding to the estimated piercing points of the GNSS satellite-receiver links. The variations in TEC measurements are identified from the data taken from GNSS receivers placed in Ramsfjordbotn and in Tromsø with a separation of approximately 14 km. During the heating experiments GLONASS satellites are in the field of view of the receivers at high elevation angle. The links between a satellite and a receiver crossing the estimated heating area is capable of providing information about plasma irregularities along the intersection. The simultaneous measurements from the two different receivers allow detecting horizontal structures in the vicinity of the perturbed ionospheric plasmas if the distances between two piecing points are comparable to the size of heated area. The TEC variations are analyzed with regard to the relative distance between each piercing point and the heating center over a series of heating intervals. It is shown that the effects of successive changes of the heating times on the perturbed plasma density structures can be implied from the GNSS TEC signals. The results suggest that the oscillation signature of the TEC may result from the irregularities in the plasmas excited by the different HF heating intervals.

  7. Seasonal and solar cycle variations in the ionospheric convection reversal boundary location inferred from monthly SuperDARN data sets

    NASA Astrophysics Data System (ADS)

    Koustov, Alexander V.; Fiori, Robyn A. D.

    2016-02-01

    Multi-year (1995-2013) velocity data collected by the Super Dual Auroral Network (SuperDARN) HF radars are considered to investigate seasonal and solar cycle variations of the convection reversal boundary (CRB) location for interplanetary magnetic field (IMF) Bz < 0. By considering monthly data sets we show that the CRB is at higher latitudes in summer between 1995 and 2007. The poleward shifts are on the order of 2-5°. After 2007, the seasonal effect weakens, and the highest latitudes for the CRB start to occur during the winter time. We show that the CRB latitudes decrease with an increase of the IMF transverse component at a rate of (1-2°)/2 nT. Because of this effect, on average, the CRB latitudes are lower during high solar activity periods with stronger IMFs. We also confirm the effect of the CRB dawn-dusk shifts related to the IMF changes in the IMF By sign.

  8. 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.

  9. Plasma dynamics driven by finite-width current filament and KV potential drops in ionosphere-magnetosphere coupling

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    We have simulated the plasma dynamics of a quasi-two-dimensional current filament in ionosphere-magnetosphere coupling. The simulation consists of a set of one-dimensional flux tube simulations with different imposed time-dependent, field-aligned currents. The dynamical interactions of the individual current filaments with the ionospheric and magnetospheric plasma generate kV field-aligned potential drops along the field lines, and the side-by-side display exhibits the evolution of the implied potential structure in the horizontal direction. The primary cross-field motion produced by the horizontal E-field (ExB drift) is perpendicular to both of the significant spatial directions, and is thus ignorable in this geometry. The effects of other cross-field drict processes are discussed. The simulation thus provides insight into the dynamical evolution of 2D potential structures driven by an imposed finite-width field-aligned current profile. Spatial and temporal variation of other plasma parameters (temperatures, density, etc.) that are determined primarily by parallel transport effects are also displayed.

  10. A Multispacecraft/Instrument Case Study of the Relationship Between the Solar Wind and Ionospheric Plasma Outflow

    NASA Technical Reports Server (NTRS)

    Craven, Paul D.; Chandler, M. O.; Moore, T. E.; Mozer, F.; Russell, C. T.

    2001-01-01

    The study of the relationship between the solar wind and ionospheric plasma outflows is fundamental to understanding the solar- terrestrial relationship. A multi-spacecraft/instrument case study has been carried out to address this relationship. On 11-26-00 the Polar spacecraft made a pass through the southern cleft region near perigee where the Thermal Ion Dynamics Experiment (TIDE) instrument observed a classic Cleft Ion Fountain/upwelling ion signature. These observations followed several pressure pulses from the solar wind as evidenced by observations from the Magnetic Field Instrument (MFI) on the WIND spacecraft. Several interesting electric field features were observed by the Electric Field Instrument (EFI) as Polar appeared to pass through a narrow region of strong currents into a region with significant oscillations at a large range of frequencies. In addition, coincident with the TIDE observations of ion outflow, the low-energy edge of the characteristic V-shape of cusp ion injections was also observed. During this same time frame the Cluster spacecrafts crossed the magnetopause in the dusk sector and observed the electric field signatures associated with this region on all three satellites. This event is addressed in detail to further detail cleft ion fountain source characteristics, to add additional data regarding the hypothesis that solar wind pressure pulses are a trigger for cleft outflow, and to investigate possible interactions among waves, ionospheric plasma, and cusp injected plasma.

  11. The ‘churning mode’ of plasma convection in the tokamak divertor region

    NASA Astrophysics Data System (ADS)

    Ryutov, D. D.; Cohen, R. H.; Farmer, W. A.; Rognlien, T. D.; Umansky, M. V.

    2014-08-01

    The churning mode can arise in a toroidally-symmetric plasma where it causes convection in the vicinity of the poloidal magnetic field null. The mode is driven by the toroidal curvature of magnetic field lines coupled with a pressure gradient. The toroidal equilibrium conditions cannot be satisfied easily in the virtual absence of the poloidal field (PF)—hence the onset of this mode, which ‘churns’ the plasma around the PF null without perturbing the strong toroidal field. We find the conditions under which this mode can be excited in magnetic configurations with first-, second-, and third-order PF nulls (i.e., in the geometry of standard, snowflake and cloverleaf divertors). The size of the affected zone in second- and third-order-null divertors is much larger than in a standard first-order-null divertor. The proposed phenomenological theory allows one to evaluate observable characteristics of the mode, in particular the frequency and amplitude of the PF perturbations. The mode spreads the tokamak heat exhaust between multiple divertor legs and may lead to a broadening of the plasma width in each leg. The mode causes much more intense plasma convection in the poloidal plane than the classical plasma drifts.

  12. Nonlinear coupling of lower hybrid waves to the kinetic low-frequency plasma response in the auroral ionosphere

    NASA Astrophysics Data System (ADS)

    Sanbonmatsu, K. Y.; Goldman, M. V.; Newman, D. L.

    A hybrid kinetic-fluid model is developed which is relevant to lower hybrid spikelets observed in the topside auroral ionosphere [Vago et al., 1992; Eriksson et al., 1994]. In contrast to previous fluid models [Shapiro et al., 1995; Tam and Chang, 1995; Seyler, 1994; Shapiro et al., 1993] our linear low frequency plasma response is magnetized and kinetic. Fluid theory is used to incorporate the nonlinear wave coupling. Performing a linear stability analysis, we calculate the growth rate for the modulational instability, driven by a lower hybrid wave pump. We find that both the magnetic and kinetic effects inhibit the modulational instability.

  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. 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.

  15. Ionospheric Pc5 plasma oscillations observed by the King Salmon HF radar and their comparison with geomagnetic pulsations on the ground and in geostationary orbit

    NASA Astrophysics Data System (ADS)

    Sakaguchi, K.; Nagatsuma, T.; Ogawa, T.; Obara, T.; Troshichev, O. A.

    2012-03-01

    We analyzed Pc5 (1.7-6.7 mHz) oscillations of ionospheric Doppler plasma velocity observed on a westward pointing beam 3 of the SuperDARN King Salmon HF radar in Alaska during the solar maximum in 2002 and the minimum in 2007. Local time distributions of the ionospheric Pc5 oscillations showed peculiar asymmetric characteristics in both years; that is, the occurrence probability had a maximum around the magnetic midnight, whereas backscatter echoes exhibited almost no oscillation on the dayside. We compared these ionospheric Pc5 events with magnetic field variations on the ground under the radar beam at Pebek and King Salmon and the geostationary ETS-8 satellite at almost conjugate longitude. We found only a few nightside events where both the radar and magnetometers detected similar sinusoidal oscillations. On the other hand, from statistical spectral analyses we found that there were positive correlations between the integrated Pc5 range spectral power of velocity oscillations and the geomagnetic pulsations both on the ground and in geostationary orbit although the pulsation powers were quite low. For these ionospheric Pc5 events, we found that both solar wind bulk flow speed and dynamic pressure showed no correlation with the spectral power and more than half of the Pc5 events were observed when the geomagnetic activities were low as inferred from the AE and Dst indices. These results indicate that the azimuthal Pc5 oscillation in the ionospheric plasma flow does not represent well-known characteristics of Pc5 pulsations driven by solar wind changes. We consider that the nightside occurrence peak of the ionospheric Pc5 oscillation might be related to diurnal changes in the ionospheric conductivity, which controls the amplitude of wave electric fields in the ionosphere. Therefore, the Pc5 wave power distributions obtained by radar observations provide features different from those obtained from magnetic field observations.

  16. A snowflake divertor: reduction of the ELM heat load due to plasma convection

    NASA Astrophysics Data System (ADS)

    Ryutov, D. D.; Cohen, R. H.; Rognlien, T. D.; Umansky, M. V.

    2011-10-01

    A snowflake magnetic configuration is created when the poloidal magnetic field and its spatial derivatives turn zero at a certain point. The separatrix then acquires a characteristic hexagonal shape reminiscent of a snowflake and the number of divertor plate strike points increases from two to four. We point out that the snowflake divertor could solve the ELM heat load problem by spreading the heat over a large area and engaging all four strike points. The mechanism is related to a fast increase of the plasma beta in the divertor region during ELM. Due to very low values of the poloidal magnetic field over a large area of a snowflake divertor, plasma convection sets in that leads to the desired effect. Conditions for the onset of a convective instability and/or the loss of equilibrium are formulated, and estimates of the size of the zone involved in convective motion are presented. Work performed for U.S. DoE by LLNL under Contract DE-AC52-07NA27344.

  17. Geomagnetic response of the polar thermosphere and ionosphere.

    NASA Astrophysics Data System (ADS)

    Rees, D.; Fuller-Rowell, T. F.

    A self-consistent coupled thermospheric / ionospheric model has been developed by merging the University College London Global Thermospheric Model and the Sheffield University Ionospheric Model. The neutral thermospheric wind velocity, composition, density, and energy budget are computed, including their full interactions with the high-latitude ion drift, precipitation, Joule heating and plasma density. This model has been used to examine thermospheric and ionospheric coupling within the polar cap, polar cusp and auroral oval. Simulations have been performed corresponding to high solar activity, moderate geomagnetic activity (Kp = 3), for the June and December solstices, and for convection electric field patterns corresponding to positive and negative values of the IMF-BY component to examine variations with season, and responses to the interplanetary magnetic field.

  18. A study of the ionospheric signature of ion supply from the ionosphere to the magnetosphere

    SciTech Connect

    Loranc, M.A.P.

    1988-01-01

    Recent studies have demonstrated the importance of the ionosphere as a source of magnetospheric plasma; in particular, the observations of upwelling ions (UWI) by the DE-1 Retarding Ion Mass Spectrometer have illustrated the significance of low-energy ion supply to the magnetosphere. The composition of the UWI implies an ionospheric source, and the Dynamics Explorer dual satellite mission provides an opportunity to search for the ionospheric signature of UWI. Magnetometer data from both satellites are used to determine magnetic conjunctions of the satellites; these conjunctions are searched for correlated observations of UWI and upward flowing thermal ion (UFI) events. Four cases of correlated observations are presented as proof of that the UFI are indeed the ionospheric signature of UWI; it is found from these examples that the event are associated with intense field-aligned currents at both satellites and with anti-sunward convection, enhanced fluxes of low-energy precipitating electrons from the boundary plasma sheet, and upward thermal ion fluxes in excess of 10{sup 9} cm{sup {minus}2} s{sub {minus}1} at DE-2. While USI are primarily a dayside phenomena, UFI are found in all local time sectors sampled by DE-2.

  19. Direct interlink of plasma in the convection zone and in the corona

    NASA Astrophysics Data System (ADS)

    Shibasaki, K.

    2014-12-01

    Thermal plasma particles in a magnetic field have a magnetic moment due to Lorentz force. The magnetic moment is anti-parallel to the field direction (diamagnetic) and is inversely proportional to the field strength. It does not disappear even under highly collisional condition. The magnetic flux density (or magnetic field, B) in a magnetized media is determined as B = μ0(H+M), where μ0 is the magnetic permeability of the vacuum, H is the magnetic intensity, and M is the magnetic moment per unit volume. This means that the magnetic field in a plasma is a self-consistent field (B is a function of B itself) and has some restrictions. Under high plasma beta condition, this restriction results in spontaneous formation of magnetic flux tubes. Hence, in the solar convection zone where the gas pressure is high, the magnetic field can exists as concentrated flux tubes. Plasma particles inside and outside the tube are rather independent even in a low ionization degree plasma due to frequent collisions. Plasma particles inside the flux tube are pushed upwards along the field due to the diamagnetic moment (mirror force) against the gravity force. The hot coronal plasma can be supplied directly from below through magnetic flux tubes. Coronal heating and other important questions can be understood by this simple mechanism.

  20. Ionospheric plasma turbulence over region of 2006 Iran, 2005 Lake Tanganyika and 2010 New Britain Region earthquakes.

    NASA Astrophysics Data System (ADS)

    Kosciesza, Malgorzata; Blecki, Jan; Wronowski, Roman; Parrot, Michel

    2013-04-01

    We report the results of the observation of ELF plasma turbulence registered by DEMETER satellite in the ionosphere over epicenter region of three earthquakes. First one took place on 2nd of February 2005 in Lake Tanganyika Region with magnitude 6.9. Second was earthquake with magnitude 6.1 in Iran on 31st March 2006. The last one took place on 4th of August 2010 in New Britain Region with magnitude 7.0. Obtained results we compare with data gathered during corresponding time and region with quiet seismic conditions. To study this turbulent processes we apply Fourier, wavelet, bispectral analysis and statistical description with use of kurtosis and skewness of the electric field fluctuations. These registrations are correlated with the plasma parameters measured onboard DEMETER satellite and with geomagnetic indices.

  1. 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, Vah; 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, significant changes to the magnetospheric configuration caused by the variations in solar wind dynamic pressure, most notably the two pressure peaks at 2345 and 0145 UT resulted in a relative absence of O + ions from the magnetotail extending from 0140 to 0300 UT. After 0300 UT, and for the next hour, the O + density in the plasma sheet increased to >1 cm -3, and O + was more abundant in the magnetotail compared even to the period immediately following the storm commencement.

  2. Experimental observation of a ''convective cell'' in electron phase space in an inductively coupled radio-frequency plasma

    SciTech Connect

    Kortshagen, U.; Heil, B.

    2000-08-28

    Spatially resolved two-dimensional Langmuir-probe measurements of energy-resolved electron fluxes have been performed in an inductively coupled radio-frequency plasma. A flux pattern reminiscent of a ''convection cell'' in energy-configuration space has been observed. The measurements are interpreted in terms of a total-energy picture of the plasma electrons. (c) 2000 American Institute of Physics.

  3. On the plasma sheet dependence on solar wind and substorms and its role in magnetosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Sergeev, V. A.; Dmitrieva, N. P.; Stepanov, N. A.; Sormakov, D. A.; Angelopoulos, V.; Runov, A. V.

    2015-12-01

    Recently, it was argued that Hall conductivity and peak intensity of equivalent ionospheric currents are sensitive to the amount of field-aligned acceleration of plasma sheet (PS) electrons, which in turn depends on the plasma sheet parameters T e and N e (electron temperature and density) proportionally to the quantity eTN = ( T e)1/2/ N e. Here we extend these studies using data from six tail seasons of THEMIS observations to show statistically that the behavior of these PS electron parameters, measured in the middle of the nightside plasma sheet at ~10 RE distance, depends in a very different way on two basic processes: the solar wind state and substorms. We confirm previous work that slow/dense (fast/tenuous) solar wind provides cold/dense (hot/tenuous) plasma sheet conditions. However, we find that electron temperature and pressure parameters ( T e and P e) behave differently from the proton ones ( T p and P p), indicating a strong decoupling between temperature variations of auroral protons and electrons in the central plasma sheet (CPS): electrons are more sensitive to the substorm-related acceleration in the magnetotail than protons. Our superposed epoch study of plasma sheet parameter variations during substorms as well as our analysis of plasma acceleration at dipolarization fronts shows that during the substorm expansion phase a new (accelerated and plasma-depleted) population comes into the inner CPS with the flow bursts, showing an average increase of electron temperature and eTN parameter roughly by a factor of 2 above its background values for both cold/dense and hot/tenuous plasma sheet states. Preferential electron heating in the flow bursts is also statistically confirmed.

  4. Nonlinear dynamics of the 3D FMS and Alfven wave beams propagating in plasma of ionosphere and magnetosphere

    NASA Astrophysics Data System (ADS)

    Belashov, Vasily

    We study the formation, structure, stability and dynamics of the multidimensional soliton-like beam structures forming on the low-frequency branch of oscillation in the ionospheric and magnetospheric plasma for cases when beta=4pinT/B(2) <<1 and beta>1. In first case with the conditions omega>{k_{yz}}(2,) v_{x}$<plasma parameters and the angle Theta=(B,k) [2]. In another case the dynamics of the finite-amplitude Alfvén waves propagating in the ionosphere and magnetosphere near-to-parallel to the field B is described by the 3D derivative nonlinear Schrödinger (3-DNLS) equation for the magnetic field of the wave h=(B_{y}+iB_{z})/2B/1-beta/ [3]. To study the stability of multidimensional solitons in both cases we use the method developed in [2] and investigated the Hamiltonian bounding with its deformation conserving momentum by solving the corresponding variation problem. To study evolution of solitons and their collision dynamics the proper equations were being integrated numerically using the codes specially developed and described in detail in [3]. As a result, we have obtained that in both cases for a single solitons on a level with wave spreading and collapse the formation of multidimensional solitons can be observed. These results may be interpreted in terms of self-focusing phenomenon for the FMS and Alfvén waves’ beam as stationary beam formation, scattering and self-focusing of wave beam. The soliton collisions on a level with known elastic interaction can lead to formation of complex structures including the multisoliton bound states. For all cases the problem of multidimensional soliton dynamics in the ionospheric and magnetospheric plasma including all stages of their evolution and collision dynamics is investigated in detail. References 1. Karpman V.I., Belashov V.Yu. Physics Letters, 1991, V. 154A, N 3/4, P. 131. 2. Belashov V.Yu. Plasma Phys. And Contr. Fusion, 1994, V. 36, P. 1661. 3. Belashov V.Yu., Vladimirov S.V., Solitary Waves in Dispersive Complex Media. Theory, Simulation, Applications. Springer-Verlag GmbH & Co. KG, 2005, 305 p.

  5. 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.

  6. Intermittent convective transport carried by propagating electromagnetic filamentary structures in nonuniformly magnetized plasma

    SciTech Connect

    Xu, G. S.; Naulin, V.; Rasmussen, J. Juul; Nielsen, A. H.; Fundamenski, W.; Wan, B. N.

    2010-02-15

    Drift-Alfven vortex filaments associated with electromagnetic turbulence were recently identified in reversed field pinch devices. Similar propagating filamentary structures were observed in the Earth magnetosheath, magnetospheric cusp and Saturn's magnetosheath by spacecrafts. The characteristics of these structures closely resemble those of the so-called mesoscale coherent structures, prevailing in fusion plasmas, known as 'blobs' and 'edge localized mode filaments' in the boundary region, and propagating avalanchelike events in the core region. In this paper the fundamental dynamics of drift-Alfven vortex filaments in a nonuniformly and strongly magnetized plasma are revisited. We systemize the Lagrangian-invariant-based method. Six Lagrangian invariants are employed to describe structure motion and the resultant convective transport, namely, magnetic flux, background magnetic energy, specific entropy, total energy, magnetic momentum, and angular momentum. The perpendicular vortex motions and the kinetic shear Alfven waves are coupled through the parallel current and Ampere's law, leading to field line bending. On the timescale of interchange motion tau{sub perpendicular}, a thermal expansion force in the direction of curvature radius of the magnetic field overcomes the resultant force of magnetic tension and push plasma filament to accelerate in the direction of curvature radius resulting from plasma inertial response, reacted to satisfy quasineutrality. During this process the internal energy stored in the background pressure gradient is converted into the kinetic energy of convective motion and the magnetic energy of field line bending through reversible pressure-volume work as a result of the plasma compressibility in an inhomogeneous magnetic field. On the timescale of parallel acoustic response tau{sub ||}>>tau{sub perpendicular}, part of the filament's energy is transferred into the kinetic energy of parallel flow. On the dissipation timescale tau{sub d}>>tau{sub perpendicular}, the kinetic energy and magnetic energy are eventually dissipated, which is accompanied by entropy production, and in this process the structure loses its coherence, but it has already traveled a distance in the radial direction. In this way the propagating filamentary structures induce intermittent convective transports of particles, heat, and momentum across the magnetic field. It is suggested that the phenomena of profile consistency, or resilience, and the underlying anomalous pinch effects of particles, heat, and momentum in the fusion plasmas can be interpreted in terms of the ballistic motion of these solitary electromagnetic filamentary structures.

  7. Modeling the interaction between convection and nonthermal ion outflows

    NASA Astrophysics Data System (ADS)

    Varney, R. H.; Wiltberger, M.; Lotko, W.

    2015-03-01

    Initial demonstrations of an ionosphere/polar wind model including a phenomenological treatment of transverse heating by wave particle interactions (WPIs) are presented. Tests with fixed WPI parameters in a designated heating region on the dayside with time-varying convection show that the parameters of the resulting nonthermal ion outflow are strongly coupled to the convection. The hemispheric outflow rate is positively correlated with the convection speed with a time delay related to the travel time to the upper boundary. Increases in convection increase the thermal plasma access to the heating region, both by increasing the upflow associated with frictional heating and by increasing the horizontal transport. The average parallel velocities and energies of the escaping nonthermal ions are anticorrelated with the convection speed due to the finite dwell time in the heating region. The computationally efficient model can be readily coupled into global geospace modeling frameworks in the future.

  8. Kinetic simulation on ion acoustic wave in gas discharge plasma with convective scheme

    NASA Astrophysics Data System (ADS)

    Matsunaga, Yasushi; Hatori, Tadatsugu; Kato, Tomokazu

    2000-03-01

    In a one-dimensional plasma-sheath system representing a concave quasistationary electric potential typical of a negatively charged system, oscillations of ion are simulated by the aid of a convective scheme useful for weakly ionized plasma, and are theoretically investigated. The frequency spectra of the ion current through a cathode reveal to us that two modes of ion acoustic waves are dominant; a high and a low frequency mode. By deriving a linear differential equation with a dissipation and an ion flow, and taking for granted the sheath width and the distribution of ion flow velocity, the dispersion relation for a finite length system can be calculated. The simulation results, such as the reinforcement of the low frequency mode and the suppression of the high frequency mode, are satisfactorily corroborated by the linear theory. The instabilities of the waves are caused by the asymmetry of boundary conditions and by the dissipative effect.

  9. A Miniaturized Plasma Impedance Probe For Ionospheric Absolute Electron Density and Electron-Neutral Collision Frequency Measurements

    NASA Astrophysics Data System (ADS)

    Patra, S.; Rao, A. J.; Jayaram, M.; Hamoui, M. E.; Spencer, E. A.; Winstead, C.

    2008-12-01

    A fully integrated, low power, miniaturized Plasma Impedance Probe (PIP) is developed for small satellite constellation missions to create a map of electron density in the ionosphere. Two alternative methods for deriving plasma parameters from impedance measurements are discussed. The first method employs a frequency sweep technique, while the second employs a pulse based technique. The pulse based technique is a new method that leads to faster measurements. The two techniques necessitate different specifications for the front end analog circuit design. Unlike previous PIP designs, the integrated PIP performs direct voltage/current sampling at the probe's terminal. The signal processing tasks are performed by an off-chip FPGA to compute the impedance of the probe in the surrounding plasma. The new design includes self- calibration algorithms in order to increase the accuracy and reliability of the probe for small satellite constellation missions. A new feature included in this instrument is that the plasma parameters are derived from impedance measurements directly on the FPGA, significantly reducing the bandwith of telemetered data down to ground.

  10. 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 component of these waves is strongest in the zonal direction. These waves are strongly correlated with simultaneous observations of plasma density oscillations and appear both with, and without, evidence of larger-scale spread-F depletions. These km-scale, quasi-coherent waves strongly resemble the bottomside, sinusoidal irregularities reported in the Atmosphere Explorer satellite data set by Valladares et al. and are believed to cause scintillations of VHF radiowaves. We interpret these new observations in terms of fundamental plasma instabilities associated with the unstable, nighttime equatorial ionosphere.

  11. Ionospheric incoherent scatter results; Proceedings of Workshop V of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

    NASA Astrophysics Data System (ADS)

    Ganguly, S.

    Papers are presented on ionospheric incoherent scatter, covering topics such as F- and E- region studies by incoherent scatter radar, multiradar mapping of auroral convection, the Global Ionospheric Simultaneous Measurements of Substorms experiment, studies of the auroral ionosphere conductances, and ion flows and heating at a contracting polar-cap boundary. Other topics include the use of EISCAT radar and the Viking satellite data to study auroral electron acceleration, EISCAT measurements of pulsating aurora, observations of large field-aligned flows of thermal plasma in the auroral ionosphere, observations of atmospheric gravity waves with incoherent scatter radar, and observations of tidal modes in the lower thermosphere. Also, articles are presented on incoherent scatter spectra from non-Maxwellian plasma, radar observations of nonthermal plasmas, observations of non-Maxwellian ion velocity distributions in the auroral F-region, the effect of unresolved electrojet microstructure on measurements of irregularity drift velocity in auroral radar backscatter, and optimization of incoherent scatter measurements.

  12. The plasma environment, charge state, and currents of Saturn's C and D rings

    NASA Technical Reports Server (NTRS)

    Wilson, G. R.

    1991-01-01

    The charge state and associated currents of Saturn's C an D rings are studied by modeling the flow of ionospheric plasma from the mid- to low-latitude ionosphere to the vicinity of the rings. It is 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. The surface charge density (SCD) of these rings can show significant radial and azimuthal variations due mainly to variation in the plasma density. The SCD also depends on structural features of the rings such as thickness and the nature of the particle size distribution. The associated azimuthal currents carried by these rings also show large diurnal variations resulting in field-aligned currents which close in the ionosphere. The resulting ionospheric electric field will probably not produce a significant amount of plasma convection in the topside ionosphere and inner plasmasphere.

  13. 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.

  14. Simulation studies of long-range magnetosphere-ionosphere coupling via MHD waves

    NASA Astrophysics Data System (ADS)

    Tu, J.; Song, P.

    2012-12-01

    The long range coupling among different regions of space plasma is primarily via various waves in addition to direct flow. In the magnetosphere-ionosphere/thermosphere (M-IT) system, the coupling between the magnetosphere and ionosphere and among different regions of the ionosphere is through either the Alfven waves propagating along the magnetic field lines or the compressional waves propagating perpendicular to (or oblique to) the magnetic field lines when the flow is subsonic. In this study, we investigate magnetosphere-ionosphere/thermosphere coupling by numerically solving time-dependent continuity, momentum, and energy equations for the electrons, ions and neutrals, as well as Maxwell equations (Ampere's and Faraday's laws) and photochemistry. By including inertial terms of the momentum equations and solutions of the Maxwell equations, we retain all the possible MHD waves in the numerical simulations so that we can self-consistently examine the dynamic M-IT coupling. Simulation results for the 1-D ionosphere/thermosphere response to an imposed convection velocity at the top boundary are presented to show how the long-range coupling between the magnetosphere-ionosphere and among the different ionosphere regions is facilitated.

  15. 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.

  16. 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 Earths 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 wave frequency should be no less than 0.5 - 0.7 MHz below the F _{2} layer critical frequency f _{0F2}. In the opposed case the penetration of the radiated power behind the F _{2} ionospheric layer can take place [4]. 5. Strong variations of the electron temperature are observed inside the ducts, at the same time the ion temperature is unchanged. 6. A feature of the ducts is the presence of strong electro-magnetic field fluctuations in a frequency range from a few Hz to tens of kHz [1,5]. 7. It was revealed that the formation of the ducts in the outer ionosphere can stimulate the precipitation of energetic electrons with E ? 100 keV from the Earths radiation belts [6]. The work was supported by RFBR grants (## 12-05-00312, 13-02-12074, 13-02-12241) and by the scientific program Geophysics. References: 1. Rapoport V.O., V.L. Frolov, G.P. Komrakov, et al. // Radiophysics and Quantum Electronics, 2007. Vol. 50(8), p. 645. 2. Frolov V.L., V.O. Rapoport, G.P. Komrakov, et. al. // JETP Letters, 2008. Vol. 88, No. 12, p. 790. 3. Frolov V.L., I.A. Bolotin, V.O. Rapoport, et. al. // XXIV All-Russian conference Radio Wave Propagation. Irkutsk, 2014 (submitted for publication). 4. Frolov V.L., N.A. Mityakov, E.A. Shorokhova, M. Parrot. // Radiophysics and Quantum Electronics, 2013. Vol. 56(6), p. 325. 5. Rapoport V.O., V.L. Frolov, S.V. Polyakov, et al. // J. Geophys. Res., 2010. Vol. 115, A10322, doi:10.1029/2010JA015484. 6. Markov G.A., A.S. Belov, V.L. Frolov, et al. // JETPh, 2010. Vol. 138, No. 6(12), p. 1037.

  17. 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 data.

  18. TIGER HF radar study of sub-auroral plasma convection response to substorm onset

    NASA Astrophysics Data System (ADS)

    Makarevich, Roman

    The dual HF radars comprising the Tasman International Geophysical Environment Radar (TIGER) system often observe localized high-velocity F-region plasma flows (≥ 1500 m/s) in the midnight sector (20-02 MLT) at magnetic latitudes as low as 60 deg. The flow channels exhibit large variability in the latitudinal extent and electric field strength, and are similar to the subauroral polarization stream or SAPS, a plasma convection feature thought to be related to the polarization electric field due to the charge separation during substorm and storm development. In this study, the 2-D plasma drift velocity within the channel is derived for each of the two TIGER radars from the maximum velocities measured in all 16 radar beams within the latitudinally narrow channel, and the time variation of the subauroral electric field is examined near substorm onset. It is demonstrated that the flow channel often does not have a clear onset, rather it manifests differently in different phases of its evolution and can persist for at least two substorm cycles. During the growth phase the electric fields within the flow channel are difficult to distinguish from those of the background auroral convection but they start to increase near substorm onset and peak during the recovery phase, in contrast to what has been reported previously for auroral convection which peaks just before the substorm onset and falls sharply at the substorm onset. The response times to substorm onset range from -5 to +40 min and show some dependence on the substorm location with longer delays observed for substorms eastward of the radars' viewing area. The propagation velocity of the high-velocity region is also investigated by comparing the observations from the two closely-spaced TIGER radars. The observations are consistent with the notion that the polarization electric field is established with the energetic ions drifting westward and equatorward from the initial substorm injection. The ion injection front can precede that of the electrons and hence substorm onset resulting in a negative response time of a few minutes.

  19. 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.

  20. Plasma flow reversals at the dayside magnetopause and the origin of the asymmetric polar cap convection

    SciTech Connect

    Gosling, J.T.; Thomsen, M.F.; Bame, S.J.; Elphic, R.C. ); Russell, C.T. )

    1990-06-01

    A number of events have been observed in the Los Alamos/Garching fast plasma experiment data from ISEE 2 within {plus minus} 3 hours of noon wherein the y component of the plasmas flow within the low latitude boundary layer and magnetopause current layer is oppositely directed to that in the adjacent magnetosheath. When the y component, B{sub y}, of the local magnetosheath magnetic field is positive, events of this nature are found preferentially in the northern dusk and southern dawn quadrants, and when B{sub y} is negative, they are found preferentially in the opposite two quadrants. Plasma flows in these events are always also poleward, that is they are always directed away from the GSE equatorial plane. The observations are qualitatively and quantitatively consistent with previous observations of accelerated flows at the magnetopause and with models of magnetic reconnection, with the reconnection occurring at low latitudes near the GSE XY plane independent of the magnitude or the sign of the y component of the local magnetosheath magnetic field. Local magnetic shears at the magnetopause for these events range from 60 to 180 degs, which, together with the occurrence of these events at low latitudes, does not tend to support the antiparallel merging hypothesis. These observations of B{sub y}-dependent flow reversals provide a graphic demonstration of how asymmetric polar cap convection and related phenomena, such as the Svalgaard-Mansurov effect, originate in magnetic reconnection at the dayside magnetopause.

  1. 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.

  2. 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.

  3. 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.

  4. Detection of long-living neutral hydrated clusters in laboratory simulation of ionospheric D region plasma

    NASA Astrophysics Data System (ADS)

    Sinha, H. S. S.; Oyama, Koh-Ichiro; Watanabe, S.

    2013-01-01

    The existence of hydrated cluster ions is known through in situ measurements in the D region of the ionosphere and laboratory simulation experiments. A series of experiments were conducted at Sagamihara, Japan with the intention of detecting some of the ions which, although predicted, had eluded detection in laboratory simulation. The other motivation was to look for heavier ions in laboratory simulations in conditions close to those in the D region. With the availability of better ion mass spectrometers, these could supposedly be detected by rocket measurements. Results of these experiments point to a new aspect, namely, the production of a neutral hydrated cluster molecule, which (a) has ionization potential of less than 10.2 eV, (b) has lifetimes in excess of 90 min, and (c) is formed within a limited pressure range. As this neutral cluster molecule has a mass number of 102, most probably it is NOṡ(H2O)4. A number of other important ions, which were detected earlier in laboratory experiments, were also seen in our data. These include NO+(H2O)n, NO+(H2O)nX, NO2+(H2O)n, H3O+(H2O)n, H3O+(H2O)nX, and O2+(H2O)n series. A few clusters {36+(H3O+OH), 60+(NO+NO) and 63+(NO+HO2)} and molecular ions {29+(N2H+), 33+(HO2+) and 43+(N3H+)} were also detected in these experiments. It was also found that, like the earlier experiments, the concentration of most of the hydrated ions showed an oscillatory behavior. The ion formation was observed only within a limited pressure range, which corresponds to the 50 to 100 km altitude range of the ionosphere.

  5. Space weather and the Earth ionosphere from auroral zone to equator

    NASA Astrophysics Data System (ADS)

    Biktash, L.

    2007-08-01

    Space weather conditions, geomagnetic variations, virtual ionospheric height and the critical frequency foF2 data during the geomagnetic storms are studied to demonstrate relationships between these phenomena. We examine the solar wind conditions and the auroral equatorial ionosphere response to illustrate what kind of solar wind parameters during the geomagnetic storms leads to short-term variations of the critical frequency foF2 and virtual height at the Earth ionosphere from the auroral zone to the equator. Model simulations as disturbed ionospheric wind dynamo do not allow explaining a significant part of the experimental data. Additional investigations of the ionospheric characteristics are required to clear up the origin of the short-term equatorial ionospheric variations. The critical frequency foF2 and virtual heights observed by the ionosondes are good indicators of the true layer heights and electron concentration and may provide information about the equatorial ionosphere dynamics. Intensive magnetospheric and ionospheric currents during geomagnetic storms disturb the quiet ionosphere and cause the observed short-term variations of the ionospheric characteristics. The ionosheric wind dynamo is considered as an important and the main mechanism in generation of ionospheric electric currents and fields. The disturbed ionospheric wind dynamo can be the generator of the equatorial ionospheric electric currents during geomagnetic storms in the aftermath of strong auroral heating. The magnetospheric electric field directly penetrating into the low-latitude ionosphere can be another source of electric field. During disturbed space weather conditions magnetospheric electric fields disturb the auroral ionosphere forming auroral electrojets and by the high-latitude electric field and termospheric disturbances can penetrate to the equatorial ionosphere. That is the reason the equatorial ionospheric electric field variations like geomagnetic variations are complex and result of superposition of different disturbing agents. Numerous studies present the experimental and theoretical relations between the solar wind, auroral ionosphere and geomagnetic variations. However, the equatorial ionosphere has been assumed to be free from the influence of the auroral electric fields. We study 5-min ionospheric variations using the first Western Pacific Ionosphere Campaign (1998 - 1999) observations, 5-min interplanetary magnetic field (IMF) and 5-min auroral electrojets data during a geomagnetic storm. The ionospheric 5-min variations at the equatorial stations which allow calculating in detail time delays of the auroral and equatorial ionospheric phenomena are scantily known. These data demonstrate that the auroral and the equatorial ionospheric phenomena are developed practically simultaneously. We suppose that these ionospheric phenomena are due space weather conditions and interaction between electric fields of the auroral and the equatorial ionosphere during geomagnetic storms. It is shown that the low-latitude ionosphere dynamics during these storms was defined by the southward direction of the Bz-component of the interplanetary magnetic field. A southward IMF produces the Region 1 and Region 2 the field-aligned currents (FAC) and polar electrojet current systems. We assume that the short-term ionospheric variations during geomagnetic storms can be explained mainly by the electric field of the FAC. The electric fields of the field-aligned currents can penetrate throughout the mid-latitude ionosphere to the equator and may serve as a coupling agent between the auroral and the equatorial ionosphere. We show that the equatorial ionosphere is a very sensitive indicator of the solar wind conditions and geomagnetic storms. Nowadays geomagnetic storms can be presented as a measure of energy transfer from the solar wind to the magnetosphere. Its magnitude is inevitably a function of the solar wind properties, the state of the magnetosphere, and the physical processes involved in the solar wind-magnetosphere interaction. Ionosphere effects of the solar wind is much complex. It is very difficult to separate the agents forming ionospheric disturbances during geomagnetic storms. It is considered that 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. In addition to these reasons we suppose that day-time and night-time equatorial ionosphere have to respond to westward and eastward auroral electrojets and the field-aligned currents by the different way while large-scale internal gravity waves and changes in neutral composition and in neutral wind system have to show the same effect in sign and there are problems to explain positive ionospheric storms. Furthermore, from the presented geomagnetic storms which AU and AL indices have very different amplitudes (nighttime auroral electrojets are much stronger daytime ones AL/AU5) and yet it is impossible from models to take account theses effects from termospheric models. It should be noted that amplitudes of AU and AL very variable during different storms, so there are different the IMF Bz and By patterns of auroral electrojets and related the field-aligned currents. Numerical modeling of auroral electrojets during geomagnetic disturbances effects of FAC as well as the polar cap potential drop difference in the auroral electrojet distribution and precipitation of high-energy auroral particles are considered. We suppose to explain of substorm effects in foF2 it is not enough to involve local processes but it is necessary to consider existential distribution of all parameters of near-Earth plasma. In our cases the IMF Bz and Joule heating can show the same effect to decrease of foF2 variations but quick foF2 depression and its correlation the negative the IMF Bz duration seems to show the field-aligned current effect on the equatorial ionosphere. The examples demonstrated in our study show that the strong auroral electrojets were formed by coupling of the solar wind with the magnetosphere when the Bz turned southward and the solar wind velocity increased. At the same time the equatorial night-time ionosphere parameters showed the short-term variations in the virtual ionospheric height and foF2. For example, the ionospheric heights and the critical frequency foF2 at low latitudes were very different in periods when the Bz-component turns to north (the quiet day conditions) and when Bz-component turns on south (the main phase of magnetic storms). Distinction between the quiet and disturbed periods in the heights reached values up to 150 km and more. It is also evident from these examples that the solar wind controls not only the auroral ionosphere but the eqtatorial ionosphere too. Time delay around 40 min between the Bz IMF and the equatorial ionospheric variations during the geomagnetic storms allows us to make this assumption. The latitudinal and the longitudinal extent the auroral electrojets and its movements are well determined by the IMF Bz. These conditions and a good conductivity of the night ionosphere allow the auroral electric fields move closer to the equator. In consequence, the auroral electric fields penetrate to the equator and an additional night-time current system can form at the equatorial ionosphere and change the true layer heights and electron concentration. This current system may be linked to the Region II field-aligned currents (FAC) during the westward auroral electrojet formation at the night ionosphere. It is well known that the field-aligned currents are closely connected with the auroral electrojets and the DP systems. These currents location and intensity are defined by the solar wind conditions. If the electric fields from FAC of Region II can penetrate through the midlatitudes to the low-latitude ionosphere and create the eastward equatorial electric field there then this electric field can decrease the nighttime equatorial electrojet current and increase the ionospheric plasma vertical drift velocity. In this case, the plasma moves upward away from the F layer, the F2 maximum is observed at the greater heights and one can see the foF depression caused by the upward movement of electrons. Unfortunately, we do not have high latitude ionospheric data with 5-15 min resolution for our data, resolution auroral indices too rough for calculation of time-delay. Furthermore, the auroral and equatorial ionospheric variations have differences associated with geomagnetic field of the Earth that produce addition troubles for comparison. It should be noted also that during geomagnetic storms the low latitude stations can provide more precision measurements than auroral stations. It is well known that auroral zones are the major regions of the ionospheric instability, especially during geomagnetic storms and substorms. The equatorial ionosphere has often been neglected and only the auroral ionosphere had been taken into account when considering the solar wind, magnetosphere and ionosphere coupling. Therefore the coupling between high and low latitude ionosphere is the least understood aspect of this problem. In recent years one can observe a revived interest on the equatorial ionosphere because as polar the polar ionosphere it produces serious problems in communication and navigation systems during of geomagnetic disturbances and storms. Because of its high conductivity, the equatorial ionosphere in the region confined between of 20 degrees magnetic dip latitudes is very sensitive to variations of electric field due to several effects including magnetospheric convection, ionospheric dynamo disturbance, and various kinds of wave disturbances. So, from the practical point of view, the relationships between the solar wind and the ionospheric parameters can be used for prediction of different ionospheric phenomena. For example, the changes of the ionosphere height may serve as a good measure for predictions of the spread F or intense ionospheric scintillations. It should be noted that more detail investigations of the high and low latitude quantitative relationships with high-precision data are required to include in features of the ionosheric models during geomagnetic storms.

  6. 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.

  7. Stratification of magnetospheric convection

    SciTech Connect

    Trakhtengerts, V.Y.; Fel'dshtein, A.Y.

    1982-01-01

    The stability of steady-state, large-scale convection in the earth's magnetosphere with respect to low-frequency electromagnetic perturbations is studied. The excitation of small-scale Alfven waves across the magnetic field due to the relative motion of the electrons and ions in the ionosphere is studied for a dipole magnetic field. The interaction of the magnetosphere and the ionosphere is incorporated through an effective boundary condition on the ionosphere. This boundary condition applies in the case of perturbations which are highly elongated along the magnetic field. A dispersion relation is derived for the real altitude profile of the electron and ion velocities in the ionosphere. This relation is analyzed. The instability described here is used to explain periodic structures which exist in the ionosphere, the auroral arcs.

  8. 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.

  9. 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 temperature-dependent reaction rates. They can be attributed to HF-induced ionization production by accelerated electrons. The possible mechanisms for plasma modifications induced by powerful X-mode HF radio waves were discussed.

  10. Study of the Latitudinal Coherence of Neutral Wind and Plasma Irregularity Drift Coupling in the Nighttime F Region Ionosphere

    NASA Astrophysics Data System (ADS)

    Indiresan, R. S.; Niciejewski, R. J.; Groves, K. M.; Meriwether, J. W.; Valladares, C. E.; Biondi, M. A.

    2001-12-01

    Measurements of low-latitude thermospheric neutral winds made with a Fabry-Perot interferometer (FPI) at Carmen Alto, Chile and irregularity drifts obtained from spaced-receiver scintillation monitors at Antofagasta, Chile, during July-October 1997, are compared to determine the extent of plasma-neutral coupling. Similar studies are performed at near-magnetic equatorial sites using FPI neutral wind data from Arequipa, Peru and irregularity drift data from Ancon, Peru. These two data sets from sites separated by approximately 7o in latitude are compared on a daily as well as a monthly-averaged basis to investigate the latitudinal coherence of plasma-neutral coupling. Both sites exhibit the presence of good plasma-neutral coupling, especially after 2100~LT. This suggests that the neutral wind is the main driver of the nighttime F region ionosphere under observation. Moreover, the local wind effects can influence the field-line integrated drifts over a latitudinal extent of at least 7o, in this longitude sector, for the months studied. In general, the degree of coupling is seen to improve from the winter solstice (July) to equinox (October) months. This could in part be due to the fact that irregularity drifts can be estimated more accurately if scintillations are stronger. Averaged drifts are seen to be higher than winds before 2100~LT during October at the Chilean as well as the Peruvian sites. In Peru, the best correlation is seen between winds measured to the east and drifts measured to the west. In Chile, drifts measured to the west correlate well with the winds measured to the west and to the east.

  11. Small scale processes in ionosphere-magnetosphere coupling, from an ionospheric perspective.

    NASA Astrophysics Data System (ADS)

    St-Maurice, Jean-Pierre

    On a global scale, ionospheric-magnetospheric coupling is reasonably well understood in terms of Regions I and II currents and the convection patterns that they generate. However the smaller scale picture can be much more complex, with substructures in the ionosphere that do not necessarily line up with the original magnetospheric configuration, important physics introduced by very different current carriers, and with small scale plasma irregularities affecting the transport properties of the overall plasma in major ways. As a starting point, we have to recognize that the ionosphere does not react passively to electron precipitation and Alfven waves triggered by magnetospheric processes. For instance, the ionosphere reflects incoming Alfven waves by establishing the net parallel currents that must come out of the ionosphere for a given perpendicular electric field distribution associated with the impeding waves. One aspect that deserves attention is that with or without an Alfven wave transition, the vertical current distribution can be quite complex particularly when small scale conductivity gradients are taken into account. For instance, the tilt in the magnetic field can be such that in relatively narrow (km size) auroral structures, advection by Pedersen ion drifts will take the E region plasma as far as 100 km away from the region of precipitation, further modifying the conductivities and parallel current distribution in the process. In addition, above about 300 km, the currents are essentially all field-aligned. An interesting aspect is that the carriers for return currents originating from the ionosphere are cold thermal electrons moving upwards. If these returning current densities are large enough, then, somewhere above the topside, the current carriers have to switch to high energy electrons since the plasma is bound to become violently unstable to streaming instabilities. The instabilities slow down the upgoing electrons through the introduction of anomalous resistivity, in turn triggering a change in the current carriers from thermal or suprathermal to much more energetic. It can also be shown that the negative space charge in those regions is able to produce, as observed, ion conics in addition to triggering fluxes of energetic electrons. The thermal current density can also become so intense at times, that large amplitude ion acoustic waves detected as NEALS by incoherent scatter radars will be generated in the ionosphere itself through the large relative drifts between the different ion and electron populations (with relative drifts from either thermal or suprathermal electrons). It should also be recognized that even without an instability, the vertical currents generated by the ionospheric electrons will involve an increasingly large number of runaway electrons. This has been shown to increase the parallel conductivity by measurable amounts. Finally, when the perpendicular electric field exceeds 25 to 30 mV/m, strong Farley-Buneman turbulence in the E region will lead to increased electron temperatures and to changes in the ionospheric conductivities, providing yet another nonlinear feedback mechanism between the ionosphere and the magnetosphere.

  12. 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.

  13. 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.

  14. Hydromagnetic equilibrium and instabilities in the convectively driven near-Earth plasma sheet

    NASA Astrophysics Data System (ADS)

    Wu, C.-C.; Pritchett, P. L.; Coroniti, F. V.

    1998-06-01

    Recent particle simulations have suggested that the convectively driven near-Earth plasma sheet can develop a structure in which a thin current sheet is embedded within the much thicker plasma sheet and that finite-ky modes with the character of kink and interchange modes can be excited in this system. Here the ideal magnetohydrodynamic (MHD) equations are used to investigate the equilibrium and linear stability properties of such a system. It is shown that the embedded current sheet configuration satisfies the conditions of pressure balance and represents an approximate two-dimensional (x,z) MHD equilibrium state. The stability analysis, in which the boundary conditions are imposed in terms of MHD characteristic waves, indicates that two types of pressure-driven modes are unstable. One mode is associated with the presence of a tailward gradient in the equatorial magnetic field profile. As the wavelength of this mode is made shorter, the mode becomes localized on the field lines crossing the region of increasing field and has the character of an interchange/ballooning mode. A second mode is associated with the existence of a magnetic island and is localized within the island; it has a structure similar to that of the classical kink mode for a plasma column. While the MHD growth rates continue to increase at short wavelengths, at longer wavelengths determined by the ion gyroradius (kyρi<~1, where ρi is computed in the local equatorial field) they are comparable to those for the dominant nonlinear modes observed in the kinetic simulations.

  15. Effect of a plasma-wave discharge on the radiation of a dipole antenna stimulating this discharge in the lower ionosphere

    NASA Astrophysics Data System (ADS)

    Markov, G. A.; Dejneko, V. N.; Ivanov, V. N.; Martinson, A. A.; Pokhun'kov, A. A.; Chugunov, Yu. V.

    1993-04-01

    A rocket experiment on the excitation of a plasma-wave discharge in the lower ionosphere at midlatitudes is described. A 480-kHz signal was received at the earth surface from the onboard dipole antenna, in the near field of which a discharge was initiated at a distance of about 1000 km from the rocket launch site. The time structure of the signal correlated with the evolution of the discharge during the flight and indicates the strong effect of the discharge plasma on the antenna radiation characteristics: the effective dipole moment and the radiation pattern.

  16. 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). From these theoretical results we infer that all ionospheric electrons and ions species (including the O+ ions) experience an outward flow along geomagnetic field lines whose angle of dip is not too large. Since above 500 km altitude the various ions densities decrease almost exponentially with altitude with characteristic scale heights (Hions) of the order of 100 km or less, the main phase uplift of all mirror points increases the local mass density all along these field lines. This changes the plasmaspheric concentrations of the O+ ions as well as of others heavy ions in the topside ionosphere and plasmasphere. We will outline experimental tests to check this new hypothesis and physical mechanism to enhance the plasma mass density during the main phases of geomagnetic storms. A subsequent decrease of the plasma ion mass density is expected following the geomagnetic storm event, due to inverse Betatron effect during the recovery phase, and due to the effect of gravity pulling the heavier ions back to lower altitudes.

  17. Validation of GRACE electron densities by incoherent scatter radar data and estimation of plasma scale height in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Xiong, Chao; Lühr, Hermann; Ma, ShuYing; Schlegel, Kristian

    2015-04-01

    This paper presents an effort of using incoherent scatter radar data for validating electron density (Ne) measurements performed by the GRACE satellites from year 2002 to 2012. For adjusting the bias of GRACE Ne data, the observations at high latitudes from EISCAT at Tromsø and Svalbard, as well as two incoherent scatter radars (ISR) at mid- and low latitudes, Millstone Hill and Arecibo, are used. The adjusted GRACE Ne data are further compared with the observations from the four ISRs. For EISCAT observations at Tromsø and Svalbard the comparison results are quite consistent, yielding correlation coefficients as high as 0.92, and an average bias value of about 3 · 1010 m-3 is obtained. For the radars at Millstone Hill and Arecibo the results show excellent agreement, yielding correlation coefficients as high as 0.97 and an average bias of 1 · 1010 m-3. The scale factor of adjusted GRACE Ne data is lower by 1% and 5% compared to Millstone Hill and Arecibo readings, respectively. We consider these differences as within the uncertainty of radar measurements. Using the adjusted GRACE Ne as well as CHAMP observations during four periods of coplanar orbits between 2003 and 2008, the plasma scale heights of the topside ionosphere are determined and further compared with IRI model predictions. We find significantly larger scale heights in particular at middle and high latitudes than expected from IRI. Outstanding are the regions of the mid-latitude electron density trough.

  18. Global Ionosphere Radio Observatory

    NASA Astrophysics Data System (ADS)

    Galkin, I. A.; Reinisch, B. W.; Huang, X. A.

    2014-12-01

    The Global Ionosphere Radio Observatory (GIRO) comprises a network of ground-based high-frequency vertical sounding sensors, ionosondes, with instrument installations in 27 countries and a central Lowell GIRO Data Center (LGDC) for data acquisition and assimilation, including 46 real-time data streams as of August 2014. The LGDC implemented a suite of technologies for post-processing, modeling, analysis, and dissemination of the acquired and derived data products, including: (1) IRI-based Real-time Assimilative Model, "IRTAM", that builds and publishes every 15-minutes an updated "global weather" map of the peak density and height in the ionosphere, as well as a map of deviations from the classic IRI climate; (2) Global Assimilative Model of Bottomside Ionosphere Timelines (GAMBIT) Database and Explorer holding 15 years worth of IRTAM computed maps at 15 minute cadence;. (3) 17+ million ionograms and matching ionogram-derived records of URSI-standard ionospheric characteristics and vertical profiles of electron density; (4) 10+ million records of the Doppler Skymaps showing spatial distributions over the GIRO locations and plasma drifts; (5) Data and software for Traveling Ionospheric Disturbance (TID) diagnostics; and (6) HR2006 ray tracing software mated to the "realistic" IRTAM ionosphere. In cooperation with the URSI Ionosonde Network Advisory Group (INAG), the LGDC promotes cooperative agreements with the ionosonde observatories of the world to accept and process real-time data of HF radio monitoring of the ionosphere, and to promote a variety of investigations that benefit from the global-scale, prompt, detailed, and accurate descriptions of the ionospheric variability.

  19. Role of Time-Varying Convection Electric Field on the Fine Structure in Cold Plasma Density Outside the Plasmapause

    NASA Astrophysics Data System (ADS)

    Sazykin, S.; Spiro, R. W.; Wolf, R. A.

    2011-12-01

    Among the long-established, but not quite understood, features of plasmaspheric morphology is the frequent presence of very fine cold particle density structures observed on radial cuts in the vicinity of the plasmapause by the OGO-5 spacecraft. This observed fine structure in the cold plasma density just outside the plasmapause has been tentatively linked to time-varying convection electric field effects. However, to date, no modeling efforts have reproduced the fine structure in the observed in situ density profiles. We present the results of a modeling study performed to investigate if realistic time-varying electric and magnetic fields can account for the observed density structuring. We use the Rice Convection Model (RCM) together with a time-dependent magnetic field to compute convection electric fields for a period of a few days prior to the selected OGO-5 events. The model-computed convection electric field varies with observed geophysical parameters over the period of simulation, and includes such realistic features such as shielding of the inner magnetosphere by region-2 Birkeland currents, subauroral polarization streams, etc. After computing the time history of the electric field we use a test particle approach to trace particles in time-dependent electric and magnetic fields to reconstruct predicted cold plasma density along the OGO-5 orbit, and compare the predicted densities with the observed values. We discuss whether the computed time-varying electric field is sufficient to account for measured density structuring, or whether additional processes are required to explain observations.

  20. 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.

  1. Electron content of the ionosphere and the plasma sphere on the basis of ATS-6-Data, NNSS-data, and ionograms. [Navy Navigation Satellite System

    NASA Technical Reports Server (NTRS)

    Leitinger, R.; Hartmann, G. K.; Davies, K.

    1976-01-01

    The reported investigation takes into account data obtained with the aid of the geostationary satellite ATS-6, the satellites of the U.S. navy navigation system (NNSS) at an altitude between 900 and 1200 km, and the satellites ISIS 1 and ISIS 2. The altitude range between ground and ATS-6 is divided into two regions, including the 'ionosphere', involving the region with an upper limit of 2000 km, and the 'plasma sphere', involving the region above an altitude of 2000 km. Data concerning the electron content obtained from different sources are compared, taking into account discrepancies between ionogram-derived values and values computed on the basis of satellite measurements. Attention is also given to the vertical electron content of the ionosphere on the basis of a combination of data obtained with the aid of the ATS-6 and the NNSS.

  2. Transmission of Stormtime Electric Field and Currents to the Mid-Equatorial Latitude Ionosphere in the Magnetosphere-Ionosphere-Ground Circuit

    NASA Astrophysics Data System (ADS)

    Kikuchi, T.; Hashimoto, K. K.; Ebihara, Y.; Nishimura, Y.; Tomizawa, I.; Nishitani, N.; Nagatsuma, T.

    2014-12-01

    Three kinds of dynamos are activated in the magnetosphere during geomagnetic storms, which supply the electric field and currents to the mid-equatorial ionosphere. At the onset of the storm, the solar wind shock activates the dynamo of the dawn-to-dusk electric field and Region-1 field-aligned currents for several to ten min, which transmit to the equatorial ionosphere and intensify the equatorial electrojet (EEJ). During the storm main phase, the southward interplanetary magnetic field (IMF) activates the dynamo of the dawn-to-dusk electric field and the R1 FACs for several hours, which develop the ring current and intensify the EEJ. During the storm recovery phase, on the other hand, the electric field and currents reverse their direction, prohibit the ring current from developing and cause the counterelectrojet in the equatorial ionosphere (CEJ). The CEJs are often observed even during the storm main phase under the relatively constant southward IMF. The long-lasting CEJs are superimposed by large amplitude impulsive/irregular CEJs. We have detected the stormtime electric fields in midlatitude with the SuperDARN radar and HF Doppler sounder in Japan during the stormtime CEJs. The long-lasting CEJs should be caused by the thermospheric wind dynamo (disturbance dynamo), but the impulsive/irregular CEJs are found to be caused by substorms as well as by convection reductions. The transmission of the electric field and currents from the magnetospheric dynamos to the mid-equatorial latitude ionosphere is explained by means of the magnetosphere-ionosphere-ground (MIG) transmission line developed by Kikuchi [JGR 2014]. The Poynting flux is transmitted to the polar ionosphere by the Alfven waves in the magnetosphere-ionosphere (MI) transmission line and by the TM0 (TEM) mode waves to the mid-equatorial ionosphere in the Earth-ionosphere waveguide (ionosphere-ground (IG) transmission line). A fraction of the Poynting flux in the IG transmission line leaks into the ionosphere, driving the ionospheric currents in the E-region and motion of plasma in the F-region. Thus, the midlatitude electric field and equatorial currents are well correlated.

  3. Do ionospheric ions directly feed the inner magnetosphere ring current?

    NASA Astrophysics Data System (ADS)

    Fennell, J. F.; Roeder, J.; Grande, M.; Perry, C.; Friedel, R.; Fritz, T.

    There has been much discussion about the ionospheric source for the ring current. Normally, the ionosphere is assumed to populate the ring current via convection and injection from the plasma sheet. There have been some observations that indicate that the ionosphere can provide energetic ions directly into the ring current regions, for example the observations of Sheldon et al.(1997). During the May 4, 1998 magnetic storm the MICS composition sensor on Polar observed bi-directional field-aligned < 10 keV oxygen ions for more than 30 minutes at L<6 Re. The ion angular distributions were indicative of energetic ionospheric outflow deep in the inner magnetosphere. These field-aligned oxygen ions were observed prior to the arrival of the shock that pushed the magnetopause inside geosynchronous on May 4. There are several similar observations in the Polar/MICS data set that will be presented and described. The existence of these stormtime field aligned ions should be considered in ENA inversion models. (Sheldon, Spence and Fennell, Observation of 40 keV Field-Aligned Subauroral Ion Beams, Geophys. Res. Lett., 25, 1617-1620, 1998.)

  4. Ionospheric beam-plasma interactions: production of quasi-mode in the ion density

    NASA Astrophysics Data System (ADS)

    Akbari, H.; Semeter, J. L.; Guio, P.

    2013-12-01

    New observations by the Poker Flat Incoherent Scatter Radar (PFISR) of the recently discovered coherent echoes [Akbari et al., 2012, 2013] suggest that the underlying beam-plasma instability occurs in a different parameter regime. These observations show simultaneous enhancements of the ion-acoustic (IA) spectrum, as well as the up- and down-shifted plasma-line spectra; the filled-in nature of these IA spectra is the subject of this study. High time-resolution measurements reveal that the IA spectrum consists of discrete peaks at frequencies less than the expected frequency of the ion-acoustic resonant mode. The superposition of these peaks will appear as a filled-in spectrum when the spectrum is averaged over many radar pulses. These peaks are the signature of non-resonant, low frequency wave modes, or quasi-modes of the plasma with subsonic speeds. Such quasi-modes can be produced by different regimes of the beam-plasma instability, as described by the Zakharov system of equations, namely the supersonic and subsonic modulational instabilities and the modified parametric decay instability. The subsonic modulational instability appears as a natural and well suited candidate due to its subsonic nature and the wavenumber range of the resulting turbulence. The drive responsible for the instability is generally assumed to be soft precipitations, i.e. electron beam of energy less than 500 eV. Such electron beam directly interacts with large-scale Langmuir waves, i.e. with small wavenumbers due to the matching resonance condition. According to Bragg scattering theory, IS radar only senses electrostatic waves at a single wavenumber. Therefore, observation of the turbulence by PFISR requires also a mechanism capable of transferring the energy to waves with larger wavenumber visible by the radar. Modulational instabilities and cavitating Langmuir turbulence are examples of such mechanisms. The results presented here are of great importance in the fundamental context of beam-plasma interactions.

  5. 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.

  6. Ionospheric variations at the time of the M8.8 Chile earthquake and statistical analysis of plasma parameters recorded by DEMETER

    NASA Astrophysics Data System (ADS)

    Parrot, M.

    2010-12-01

    DEMETER is a low orbiting satellite (650 km) which is operating more than six years to study ionospheric perturbations in relation with the seismic activity. It records wave and plasma parameters all around the Earth (except in the auroral zones) at two different local times (10.30 and 22.30 LT). This paper will present observations performed during the M8.8 Chile earthquake on February 27, 2010. They show a perturbation of the ionospheric density at the satellite altitude a few days before the quake. Publication of these results was not accepted in GRL despite the uniqueness of this observation. To reject the paper, an anonymous referee said that many other parameters can fluctuate before the quake including the stock market. It is true, but our parameter is not the London or the New York stock market; it is a physical parameter which is measured in close proximity to the earthquake. It is a parameter which characterizes the environment above the future epicentre. The physical mechanism which induces these perturbations is not yet known (there are several hypotheses) but it is know that it exists a fair weather electric field between the bottom of the ionosphere and the ground. Whatever is the mechanism, if there is a change on the ground it will be registered in the ionosphere. But it is also known that the ionosphere is highly variable and that perturbations could come from other sources (solar activity, AGW, TID, plasma dynamics, large meteorological phenomena…). Then the paper will show a new statistical analysis performed on the plasma parameters during night time. An algorithm has been implemented to detect crests and troughs in the data before earthquakes. The earthquakes have been classified depending on their magnitude, depth, and location (land, below the sea, close to a coast). Due to the orbit, DEMETER returns above the same area every day (once during day time, once during night time) but not at the same distance of a given epicentre. Then, for each earthquake, data have been checked until 15 days before the shock when the distance between the trace of the orbit and the epicentre is less than 1500 km. The results of the statistical analysis are presented as function of various parameters. A comparison is done with two other data bases where, on one hand, the location of the epicentres has been randomly modified, and on the other hand, the longitude of the epicentres has been shifted.

  7. 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 generation (via the neutral He photoionization) and loss (via the charge exchange with neutral nitrogen N2 and/or the recombination with electrons) of the daytime He+ ions are comparable during different solar activities.

  8. 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.

  9. Assessing Locations of Energy Transfer/Deposit in the Ionosphere-Thermosphere System

    NASA Astrophysics Data System (ADS)

    Tu, J.; Song, P.

    2014-12-01

    It has long been believed that most of energy transferred from the magnetosphere and deposited in the ionosphere-thermosphere system occurs in the auroral zone, the region of strong field-aligned current density. Recent observations of the Poynting flux to the ionosphere and theoretical investigations of the magnetosphere-ionosphere coupling show that the strongest energy transfer may be in the polar cap proper where the plasma flow speed is high and not where the flow reverses. This implies that the field-aligned current is not the primary agent of the energy transfer into the ionosphere-thermosphere system and that other physical progresses are at play. Recent simulation studies using an inductive-dynamic approach (including self-consistent solutions of Faraday's law and retaining inertia terms in the ion momentum equations) on the magnetosphere-ionosphere-thermosphere coupling indicate that the energy transfer is through Alfven waves propagating to the ionosphere/thermosphere and the energy deposition is via the frictional heating caused by relative motion between ions and neutrals. In this study we assess the locations of the energy transfer and deposition by employing a self-consistent inductive-dynamic ionosphere-thermosphere model. In a 2-D numerical simulation (dawn-dusk meridian plane), we solve the continuity, momentum, and energy equations for multiple species of ions and neutrals including photochemistry and Maxwell's equations. By simulating responses of the ionosphere-thermosphere system to enhanced magnetosphere convection, we show that the strongest energy transfer occurs in the polar cap proper instead of the auroral zone.

  10. Electron thermal effect on linear and nonlinear coupled Shukla-Varma and convective cell modes in dust-contaminated magnetoplasma

    NASA Astrophysics Data System (ADS)

    Masood, W.; Mirza, Arshad M.

    2010-11-01

    Linear and nonlinear properties of coupled Shukla-Varma (SV) and convective cell modes in the presence of electron thermal effects are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. In the linear case, the modified dispersion relation is given and, in the nonlinear case, stationary solutions of the nonlinear equations that govern the dynamics of coupled SV and convective cell modes are obtained. It is found that electrostatic dipolar and vortex street type solutions can appear in such a plasma. The relevance of the present investigation with regard to the Earth's mesosphere as well as in ionospheric plasmas is also pointed out.

  11. Electron thermal effect on linear and nonlinear coupled Shukla-Varma and convective cell modes in dust-contaminated magnetoplasma

    SciTech Connect

    Masood, W.; Mirza, Arshad M.

    2010-11-15

    Linear and nonlinear properties of coupled Shukla-Varma (SV) and convective cell modes in the presence of electron thermal effects are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. In the linear case, the modified dispersion relation is given and, in the nonlinear case, stationary solutions of the nonlinear equations that govern the dynamics of coupled SV and convective cell modes are obtained. It is found that electrostatic dipolar and vortex street type solutions can appear in such a plasma. The relevance of the present investigation with regard to the Earth's mesosphere as well as in ionospheric plasmas is also pointed out.

  12. Ionospheric topside sounding.

    PubMed

    Calvert, W

    1966-10-14

    Over the past few years, the satellite topside sounders have significantly contributed to the understanding of the upper ionosphere. A great quantity of radio echo data has been accumulated, from which the ionospheric electrondensity distribution can be determined. The topside measurements of electron density essentially agree with similar measurements from the ground, except for an occasional 10-percent discrepancy near the peak of the ionosphere. While horizontal non-uniformity is a likely cause, this discrepancy has not yet been adequately explained. The electron-density scale heights measured at a constant altitude indicate both a higher temperature and a heavier mean ion mass at high latitudes. At low latitudes the topside measurements have shown the detailed latitudinal structure of the equatorial anomaly, demonstrating control by the geomagnetic field. A variety of electron-density irregularities have been studied. Most are greatly elongated along the magnetic field, and produce echoes either by lateral scattering, if they are thin, or by longitudinal ducting, if they are thick. Some of the thick irregularities are continuous between the hemispheres and support conjugate echo propagation. The topside sounders have revealed the complex structure of the ionosphere near the auroral zone and at higher latitudes. At night an east-west trough of greatly reduced electron density occurs equatorward of the auroral zone. At the auroral zone itself the electron density is high and quite variable, both in space and time. The electron density at the polar cap within the auroral zone is often uniform and smooth. Ionospheric irregularities are common in the area of the trough and the auroral zone. Among other satellites, the topside sounders have been used in various plasma studies involving the excitation and propagation of waves. These studies suggest that the ionosphere is an appropriate region for future plasma physics investigations, especially with rocket and satellite payloads designed specifically for that purpose. PMID:17810299

  13. Effects of multiple scatter on the propagation and absorption of electromagnetic waves in a field-aligned-striated cold magneto-plasma: implications for ionospheric modification experiments

    NASA Astrophysics Data System (ADS)

    Robinson, T. R.

    2002-01-01

    A new theory of the propagation of low power electromagnetic test waves through the upper-hybrid resonance layer in the presence of magnetic field-aligned plasma density striations, which includes the effects of multiple scatter, is presented. The case of sinusoidal striations in a cold magnetoplasma is treated rigorously and then extended, in an approximate manner, to the broad-band striation spectrum and warm plasma cases. In contrast to previous, single scatter theories, it is found that the interaction layer is much broader than the wavelength of the test wave. This is due to the combined electric fields of the scattered waves becoming localised on the contour of a fixed plasma density, which corresponds to a constant value for the local upper-hybrid resonance frequency over the whole interaction region. The results are applied to the calculation of the refractive index of an ordinary mode test wave during modification experiments in the ionospheric F-region. Although strong anomalous absorption arises, no new cutoffs occur at the upper-hybrid resonance, so that in contrast to the predictions of previous single scatter theories, no additional reflections occur there. These results are consistent with observations made during ionospheric modification experiments at Tromsø, Norway.

  14. 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.

  15. A Modeling Study of the Latitudinal Variations in the Nighttime Plasma Temperatures of the Equatorial Topside Ionosphere During Northern Winter at Solar Maximum

    NASA Technical Reports Server (NTRS)

    Bailey, G. J.; Denton, M. H.; Heelis, R. A.; Venkatraman, S.

    2000-01-01

    Latitudinal variations in the nighttime plasma temperatures of the equatorial topside ionosphere during northern winter at solar maximum have been examined by using values modelled by SUPIM (Sheffield University Plasmasphere Ionosphere Model) and observations made by the DMSP F10 satellite at 21.00 LT near 800 km altitude. The modelled values confirm that the crests observed near 15 deg latitude in the winter hemisphere are due to adiabatic heating and the troughs observed near the magnetic equator are due to adiabatic cooling as plasma is transported along the magnetic field lines from the summer hemisphere to the winter hemisphere. The modelled values also confirm that the interhemispheric plasma transport needed to produce the required adiabatic heating/cooling can be induced by F-region neutral winds. It is shown that the longitudinal variations in the observed troughs and crests arise mainly from the longitudinal variations in the magnetic meridional wind. At longitudes where the magnetic declination angle is positive the eastward geographic zonal wind combines with the northward (summer hemisphere to winter hemisphere) geographic meridional wind to enhance the northward magnetic meridional wind. This leads to deeper troughs and enhanced crests. At longitudes where the magnetic declination angle is negative the eastward geographic zonal wind opposes the northward geographic meridional wind and the trough depth and crest values are reduced. The characteristic features of the troughs and crests depend, in a complicated manner, on the field-aligned flow of plasma, thermal conduction, and inter-gas heat transfer. At the latitudes of the troughs/crests, the low/high plasma temperatures lead to increased/decreased plasma concentrations.

  16. Venus ionosphere: photochemical and thermal diffusion control of ion composition.

    PubMed

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

    1979-07-01

    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 have been identified. The neutral gas temperature (Tn) as a function of solar zenith angle (chi) derived from measured ion distributions in photochemical equilibrium is given by Tn (K) = 323 cos(1/5)chi. 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. PMID:17778920

  17. Cold plasma heating in the plasma sheet boundary layer - Theory and simulations

    NASA Technical Reports Server (NTRS)

    Schriver, David; Ashour-Abdalla, Maha

    1990-01-01

    Satellite observations in recent years have confirmed that the plasma sheet boundary layer is a permanent feature of the earth's magnetotail located between the lobe and central plasma sheet during both quiet and active magnetic periods. Distinct features of the boundary layer include field aligned ion beams and intense electrostatic emissions known as broadband electrostatic noise. Since the plasma sheet boundary layer is a spatial feature of the magnetotail, within it will occur thermal mixing of the resident warm boundary layer plasma with inflowing (convecting) cold ionospheric plasma. A theoretical study involving linear theory and nonlinear numerical particle simulations is presented which examines ion beam instabilities in the presence of a thermally mixed hot and cold background plasma. It is found that the free energy in the ion beams can heat the cool ionospheric plasma to ambient plasma sheet boundary layer temperatures via broadband electrostatic noise. These results, along with recent observational reports that ionospheric outflow can account for measured plasma sheet densities, suggest that the ionospheric role in plasma sheet dynamics and content may be as large as the solar wind.

  18. Estimating along-track plasma drift speed from electron density measurements by the three Swarm satellites

    NASA Astrophysics Data System (ADS)

    Park, J.; Lühr, H.; Stolle, C.; Malhotra, G.; Baker, J. B. H.; Buchert, S.; Gill, R.

    2015-07-01

    Plasma convection in the high-latitude ionosphere provides important information about magnetosphere-ionosphere-thermosphere coupling. In this study we estimate the along-track component of plasma convection within and around the polar cap, using electron density profiles measured by the three Swarm satellites. The velocity values estimated from the two different satellite pairs agree with each other. In both hemispheres the estimated velocity is generally anti-sunward, especially for higher speeds. The obtained velocity is in qualitative agreement with Super Dual Auroral Radar Network data. Our method can supplement currently available instruments for ionospheric plasma velocity measurements, especially in cases where these traditional instruments suffer from their inherent limitations. Also, the method can be generalized to other satellite constellations carrying electron density probes.

  19. Two-dimensional ionospheric flow pattern associated with auroral streamers

    NASA Astrophysics Data System (ADS)

    Shi, Yong; Zesta, Eftyhia; Lyons, Larry R.; Yang, J.; Boudouridis, A.; Ge, Y. S.; Ruohoniemi, J. M.; Mende, S.

    2012-02-01

    We present direct two-dimensional flow observations and auroral images from the Super Dual Auroral Radar Network (SuperDARN) radar and Wideband Imaging Camera onboard Imager for Magnetopause-to-Aurora Global Exploration (IMAGE/WIC) imager to investigate the ionospheric flow pattern associated with auroral streamers for four events. Using the SuperDARN observations allows us to observe the flow associated with the streamers in the context of the larger-scale background convection. For all four cases studied, streamers developed from preexisting east-west (EW) arcs that initiated from bead-like or small-scale auroral intensifications around the auroral poleward boundary. We find a vortex-like flow pattern with clockwise sense surrounding both the initial auroral forms and the ensuing streamers. We also found in three cases signatures of flow bifurcations at the equatorward end of the streamers, which suggests a double vortex-like flow pattern with the counterclockwise vortex east of the clockwise one. Our results are consistent with the double-vortex flow structure that results from interchange convection associated with a plasma sheet bubble predicted by different numerical simulations. This supports several previous studies and offers more complete observational evidence that the observed flow pattern may be the ionospheric manifestation of interchange instability in the plasma sheet.

  20. 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.

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

    NASA Technical Reports Server (NTRS)

    Fejer, B. G.; De Paula, E. R.; Heelis, R. A.; Hanson, W. B.

    1995-01-01

    Ion drift meter observations from the Atmosphere Explorer E (AE-E) satellite during the period of January 1977 to December 1979 are used to study the dependence of equatorial (dip latitudes less than or equal to 7.5 deg) 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 diuurnal, seasonal, and solar cycle dependence of the logitudinally averaged drifts are consistent with results from the Jicamarca radar except near the June solstice when the AE-E nighttime downward velocities are significantly smaller than those observed by the radar. Pronounced presunrise downward drift enhancements are often observed over a large longituudinal 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.

  2. 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

  3. 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.

  4. Bands of ions and angular V's - A conjugate manifestation of ionospheric ion acceleration

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Burch, J. L.; Frahm, R. A.

    1984-01-01

    Data from the hot plasma instruments on Dynamics Explorer 1 and 2 spacecraft have been used to study the injection, drift, and subsequent precipitation of suprathermal positive ions in the auroral zone. The observation at both high and low altitudes of electron inverted 'V' events in the boundary plasma sheet (BPS) and of ion 'bands' (energy decreasing with decreasing latitude) in the adjacent central plasma sheet (CPS) leads to the following ion injection model: upward-moving energetic ion beams are injected onto BPS magnetic field lines by the electrostatic potential drops associated with electron inverted V's. As the ion beams move toward the equator and into the conjugate hemisphere they are convected to lower latitudes and into the CPS. The energy-latitude dependence of the ion bands, coupled with concurrent ion convection measurements, indicate that the ion distributions are primarily O(+), in agreement with their postulated ionospheric source.

  5. Ionospheres of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    Schunk, R. W.; Nagy, A. F.

    1980-11-01

    The theory and observations relating to the ionospheres of the terrestrial planets Venus, the earth, and Mars are reviewed. Emphasis is placed on comparing the basic differences and similarities between the planetary ionospheres. The review covers the plasma and electric-magnetic field environments that surround the planets, the theory leading to the creation and transport of ionization in the ionospheres, the relevant observations, and the most recent model calculations. The theory section includes a discussion of ambipolar diffusion in a partially ionized plasma, diffusion in a fully ionized plasma, supersonic plasma flow, photochemistry, and heating and cooling processes. The sections on observations and model calculations cover the neutral atmosphere composition, the ion composition, the electron density, and the electron, ion, and neutral temperatures.

  6. Ion densities in Titan's ionosphere, multi-instrument case study

    NASA Astrophysics Data System (ADS)

    Shebanits, O.; Wahlund, J.-E.; Edberg, N. J. T.; Crary, F. J.; Wellbrock, A.; Coates, A. J.; Andrews, D. J.; Vigren, E.; Mandt, K. E.; Waite, J. H., Jr.

    2015-10-01

    The Cassini s/c in-situ plasma measurements of Titan's ionosphere by Radio and Plasma Wave Science (RPWS) Langmuir Probe (LP), Cassini Plasma Spectrometer (CAPS) Electron (ELS) and Ion Beam (IBS) are combined for selected flybys (T16, T29, T40& T56) to further constrain plasma parameters of ionosphere at altitudes 880-1400 km.

  7. Thermospheric Wind Impacts on Ionospheric Upflow and Outflow

    NASA Astrophysics Data System (ADS)

    Burleigh, M.; Zettergren, M. D.

    2014-12-01

    Significant amounts of thermal ionospheric plasma can be transported to high altitudes in response to magnetospheric and atmospheric forcing. Soft electron precipitation serves as a heat source for the ambient F-region ionospheric electrons, which enhances the ambipolar electric field and induces upflowing ions. Frictional heating of ions from fast convection through the neutral atmosphere creates pressure-driven ion upflows. Finally, large neutral winds along the geomagnetic field may effectively lift or lower the F-region density peak. At regions above where ion upflows are typically initiated, transverse ion acceleration is thought to give upflowing ions sufficient energy to escape to the magnetosphere. This study examines how low-altitude upflow processes affect ion outflow, focusing particularly on the impacts of neutral winds. A new multi-fluid ionospheric model, which solves conservation equations for mass, momentum, and parallel and perpendicular energy is developed for this study. These fluid equations are solved for all species relevant to the E, F, and topside ionospheric regions and the system is closed through an electrostatic treatment of the auroral currents. This model is driven by the specification of field-aligned currents and a resonant transverse heating term. The model therefore encapsulates the basic ionospheric upflow processes and provides a simple way to approximate the effects of transverse heating and ion outflow. Using this model, individual species responses to electron precipitation, frictional heating, neutral winds, and transverse heating are examined to determine the effects of these low-altitude upflow processes on ion outflow. Results suggest that upflows, including those induced by neutral winds, can have a significant impact on the types and amounts of outflowing ions.

  8. Ionosphere research

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A report is presented on on-going research projects in ionospheric studies. The topics discussed are planetary atmospheres, E and F region, D region, mass spectrometer measurements, direct measurements and atmospheric reactions.

  9. Ionospheric research

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Data from research on ionospheric D, E, and F, regions are reported. Wave propagation, mass spectrometer measurements, and atmospheric reactions of HO2 with NO and NO2 and NH2 with NO and O2 are summarized.

  10. Ionospheric modeling

    NASA Astrophysics Data System (ADS)

    Dandekar, B. S.

    1982-01-01

    The purpose of this report is to familiarize a user of ionospheric models with the options presently available for ionospheric prediction and specification. Two types of ionospheric models are available: the numerical-phenomenological and theoretical models. From the numerical type, the ITS-78, IONCAP, and Bent models have been discussed. In the theoretical models the main concern is the number of parameters included in the model. Nine ionoshperic models available have been summarized. The differences and limitations of these models are compared and tabulated. This information will help a user make a judicious selection of an ionospheric model to satisfy his specific needs. The sources for obtaining the programs for these models have been listed for ready reference.

  11. 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 qualitative difference due to anisotropy. An anisotropy measure is defined, and its spatial variation determined as a signature of possible MHD instability. Extreme values are found, larger than at the source, but the plasma beta in such regions is probably so low as to render the effect inconsequential energetically. Finally, the possible consequence of 'nonadia- batic' pressure profiles on electrostatic interchanges is considered, and a boundary delineating stabilizing and destabilizing regions determined.

  12. 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.

  13. Investigation of localized 2D convection mapping based on artificially generated Swarm ion drift data

    NASA Astrophysics Data System (ADS)

    Fiori, R. A. D.; Boteler, D. H.; Koustov, A. V.; Knudsen, D.; Burchill, J. K.

    2014-07-01

    Ionospheric plasma flow is an indicator of the interconnection between the solar wind, interplanetary magnetic field (IMF), and Earth’s magnetosphere. Ionospheric convection has been mapped in the past using either a widespread data set for instantaneous convection mapping over a short time period or data from an instrument measuring convection in a spatially confined region over a long time period for the purpose of building a statistically averaged convection pattern. This study explores convection mapping using a spherical cap harmonic analysis (SCHA) technique within a localized spherical cap based on data that will be available from the Swarm three-satellite constellation. Convection is mapped in the vicinity of hypothetical Swarm satellite tracks where it is adequately constrained by data. By using statistical models to emulate Swarm measurements, we demonstrate that such mapping can be successful based on data from the Swarm A and Swarm B satellites. Convection is divided into well constrained and poorly constrained subsets to determine parameters characterizing goodness-of-fit based on known quantities. Using the subset of well constrained maps, it is determined that convection is best mapped for a spherical cap having an angular radius of θc=10°. The difference between the maximum mapped convection and the maximum velocity measured along the satellite track (Δv) is introduced to evaluate goodness-of-fit. For the examples presented in this paper, we show that a threshold value of Δv=281 m/s successfully differentiates between well and poorly constrained maps 77.6% of the time. It is shown that convection can be represented over a larger region through the use of multiple spherical caps.

  14. Bimodal Solar Wind-Magnetosphere-Ionosphere Coupling

    NASA Astrophysics Data System (ADS)

    Siscoe, G.

    2005-05-01

    Regarding its coupling to the solar wind, the magnetosphere-ionosphere system appears to be schizophrenic. That is, it seems to manifest two modes with contradictory qualities, modes that alternate depending on solar wind conditions. Normal conditions elicit the normal mode (aka the solar wind-dominated mode). But extreme conditions bring out the un-normal mode (aka the ionosphere-dominated mode). This talk emphasizes the un-normal, ionosphere-dominated mode, which makes its presence during great magnetic storms. Then the magnetosphere-confining Chapman-Ferraro current system fades away to be replaced by the region 1 currents system which links the now dominant ionosphere to the whole of geospace out to and including the bow shock. Dst no longer responds to the ram pressure of the solar wind. The electrical potential across the polar cap stops growing as solar wind driving strengthens. Instead, it becomes bound to ionospheric conductance, which as the storm intensifies transforms under local instability. The ionosphere appears to lose its grip on magnetospheric convection, although this is not certain. The plasmasphere is stripped away, most likely to feed (by global circulation) an intensifying ring current. The outer magnetosphere begins a series of slow, macroscale convulsions. Huge parallel potentials possibly develop in the magnetosphere's outer regions, reacting against the ionosphere's domination. Compared to the solar wind-dominated magnetosphere, the ionosphere-dominated magnetosphere is comparatively unknown and, so, provides opportunities for significantly advancing our understanding of the coupled solar wind-magnetosphere-ionosphere system.

  15. HF modulated ionospheric currents

    NASA Astrophysics Data System (ADS)

    Payne, J. A.; Inan, U. S.; Foust, F. R.; Chevalier, T. W.; Bell, T. F.

    2007-12-01

    The HAARP HF facility is used to modulate the components of the auroral electrojet that flow in the D-region of the ionosphere, creating ELF/VLF radiation which is then measured at a receiver co-located with the HAARP HF antenna. An HF heating model is coupled to a full wave plasma interaction FDTD code to determine the ELF/VLF response of the ionospheric plasma to the modulated HF stimulation. The predicted FDTD fields on the ground are found to be in remarkable agreement with those measured at a receiver co-located with HAARP. The FDTD code also predicts an upwardly propagating whistler mode that is tightly bound to the magnetic field lines.

  16. 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, inner regions of geospace.

  17. The Response of the Thermosphere and Ionosphere to Magnetospheric Forcing

    NASA Astrophysics Data System (ADS)

    Rees, D.; Fuller-Rowell, T. J.

    1989-06-01

    During the past six years, rapid advances in three observational techniques (ground-based radars, optical interferometers and satellite-borne instruments) have provided a means of observing a wide range of spectacular interactions between the coupled magnetosphere, ionosphere and thermosphere system. Perhaps the most fundamental gain has come from the combined data-sets from the NASA Dynamics Explorer (DE) Satellites. These have unambiguously described the global nature of thermospheric flows, and their response to magnetospheric forcing. The DE spacecraft have also described, at the same time, the magnetospheric particle precipitation and convective electric fields which force the polar thermosphere and ionosphere. The response of the thermosphere to magnetospheric forcing is far more complex than merely the rare excitation of 1 km s-1 wind speeds and strong heating; the heating causes large-scale convection and advection within the thermosphere. These large winds grossly change the compositional structure of the upper thermosphere at high and middle latitudes during major geomagnetic disturbances. Some of the major seasonal and geomagnetic storm-related anomalies of the ionosphere are directly attributable to the gross wind-induced changes of thermospheric composition; the mid-latitude ionospheric storm `negative phase', however, is yet to be fully understood. The combination of very strong polar wind velocities and rapid plasma convection forced by magnetospheric electric fields strongly and rapidly modify F-region plasma distributions generated by the combination of local solar and auroral ionization sources. Until recently, however, it has been difficult to interpret the observed complex spatial and time-dependent structures and motions of the thermosphere and ionosphere because of their strong and nonlinear coupling. It has recently been possible to complete a numerical and computational merging of the University College London (UCL) global thermospheric model and the Sheffield University ionospheric model. This has produced a self-consistent coupled thermospheric--ionospheric model, which has become a valuable diagnostic tool for examining thermospheric--ionospheric interactions in the polar regions. In particular, it is possible to examine the effects of induced winds, ion transport, and the seasonal and diurnal U.T. variations of solar heating and photoionization within the polar regions. Polar and high-latitude plasma density structure at F-region altitudes can be seen to be strongly controlled by U.T., and by season, even for constant solar and geomagnetic activity. In the winter, the F-region polar plasma density is generally dominated by the effects of transport of plasma from the dayside (sunlit cusp). In the summer polar region, however, an increase in the proportion of molecular to atomic species, created by the global seasonal circulation and augmented by the geomagnetic forcing, controls the plasma composition and generally depresses plasma densities at all U.Ts. A number of these complex effects can be seen in data obtained from ground-based radars, Fabry--Perot interferometers and in the combined DE data-sets. Several of these observations will be used, in combination with simulations using the UCL--Sheffield coupled model, to illustrate the major features of large-scale thermosphere--ionosphere interactions in response to geomagnetic forcing. The past decade has seen a major improvement in the quality and quantity of experimental data available to study the thermosphere and ionosphere and their response to magnetospheric forcing. Earlier, large measured changes of individual parameters were difficult to place in a global or large-scale perspective. However, a clear picture of the distinction between the solar and geomagnetic forcing processes has emerged from the combined data-sets available from spacecraft such as the Dynamics Explorers, and from ground-based radar and optical observations of the polar thermosphere. A first experimental view of the strong coupling between the thermosphere and ionosphere has also emerged from these combined new data-sets. In parallel with the development of observing techniques, numerical models of the thermosphere and ionosphere have matured. We are at a state where the combined thermosphere and ionosphere can be modelled self-consistently. We can now realistically simulate the response of the combined system to the magnetospheric forcing, and also investigate the many and varied feedback processes between the two components. The models can be used to understand and interpret the diversity of experimental observations, and provide the framework for evaluating phenomena which are as yet not well understood. The dominant thermosphere--ionosphere interactions which appear from the modelling studies and which have counterparts in the experimental database can be summarized. In the winter polar region, ionization enhancements are observed which are due to auroral particle precipitation in both the E-region and in the F-region. The former are relatively easy to understand, since decay rates are generally rapid, and large-scale transport is unimportant. The sole caveat will be related to sporadic-E layers of long-lived metallic ions. In the polar F-region, neutral winds, neutral composition changes, convection changes and solar photoionization all cause important modifications of plasma distributions. In the winter, plasma convection and winds cause important effects in the horizontal and vertical transport of plasma, respectively. As such, plumes of high density (or low-density) plasma are transported large distances from their origin, and local plasma densities are rarely explicable by local sources and sinks. The exact distributions will depend very much on detailed plasma convection patterns. However, the winter subauroral trough and localized polar troughs will be created when the combination of convection and corotation cause plasma stagnation in regions out of sunlight and photoionization. There is a strong U.T. modulation of plasma density within the winter polar cap and dusk auroral oval (generally) as the polar cusp enters sunlight for a few hours around 18h U.T., and there is a direct source of high-density plasma (photoionization plus particle ionization) convected through the cusp. At other U.Ts, the source is generally cut off, and polar plasma densities generally decay. Summer F-region high-latitude and polar plasma densities are generally a factor of about 3-5 lower than in winter. This is due to the seasonal F-region neutral composition variation, generated by summer to winter mean circulation, by which increased plasma recombination rates (due to much higher molecular nitrogen densities) more than compensate for the increased solar photoionization source in the summer polar cap. In turn, this mean circulation is generated by the combination of asymmetric solar insolation and greater geomagnetic heating in the summer compared with winter polar regions (Rees et al. 1985, 1987). Particularly at times of high geomagnetic activity, the summer `F-region' neutral composition is close to that of the standard atmosphere E-region. The major features of the summer polar F-region are thus quite different to those of the corresponding winter region. Plasma troughs develop in regions of very strong Joule heating, i.e. where ion convection is strongest. As such, the location and intensity of the troughs is quite dependent on the plasma convection patterns. Summer-time troughs tend to occur in the same regions where rapid transport causes high-density plasma plumes in the winter polar region. The classical subauroral trough is distinctly a feature of the winter polar F-region. Even at equinox, the full subauroral trough does not develop, while in winter it fully encircles the geomagnetic polar cap for much of the U.T. day (except around 18h U.T.). In the summer F-region, stagnation troughs do not develop within the polar cap, irrespective of convection pattern. Any polar cap troughs are a result of changes in neutral composition. Subauroral troughs can only develop around the summer polar region when the auroral oval is expanded so that the midnight part of the auroral oval extends into the nightside. Conditions for this situation are likely to occur preferentially in the southern polar region, due to the greater offset of the geomagnetic from geographic pole. The E-region response to geomagnetic forcing is also strong, although generally rather less marked than in the F-region, in terms of the neutral thermal and compositional response. The major feed-back between the thermosphere and ionosphere occurs due to the effects of high induced winds, since the neutral chemical changes do not significantly affect the ionospheric chemistry. Apart from localized effects such as sporadic-E layers, high-speed auroral oval winds do not cause significant vertical transport of E-region molecular species, due to rapid recombination. The most significant vertical transport effects will be in non-sunlit regions, where ion production is lowest. The dynamo effect of induced E-region winds of 200-400 m s-1 is also quite significant. Such winds reduce horizontal currents, with an implication that the FAC or Pedersen currents may also be decreased, with a possible feedback to the convection electric field. There is still relatively little data available for detailed case-study comparisons. Such studies have been quite successful in improving our understanding of the F-region behaviour, and the CEDAR initiative and programmes such as LTCS promise to extend the range of multiparameter data-sets to the E-region as well. Simulating atmospheric density and compositional structure with numerical models is one of the most testing demands. Density at a given altitude is very sensitive to the total thermospheric energy budget, and is thus liable to be the first casualty of cumulative small errors in the many external terms of the energy input. There are also some indeterminate factors in the radiative energy budget of the lower thermosphere and upper mesosphere. In practice, we have found that the present version of the coupled model computes density and composition relatively accurately, compared with mean mass spectrometer and incoherent scatter (MSIS) predictions for comparable solar and geomagnetic activity levels and for different seasonal conditions. Typical differences (MSIS to model) of around 20% occur at F-region altitudes in the data-sets shown in the model simulations described within this paper. This is roughly comparable with the standard deviation of MSIS in comparison with satellite data-sets for specific locations and times. The numerical models have greater spatial and temporal resolution than MSIS models and relate to real physical processes. Undoubtedly, however, the real thermosphere contains a whole spectrum of high-frequency variations which are beyond present parametrization techniques, our current description of geomagnetic inputs and present computer limitations. From the initial coupled-model simulations it is possible to examine key features of the coupling between the magnetosphere and the thermosphere--ionosphere. Field-aligned currents reflect the divergence or convergence of the ionospheric Pedersen current. The Pedersen current depends on changes of the ionospheric conductivity and also the dynamo effects of induced winds. Both FAC and E-region winds display considerable seasonal, U.T. and geomagnetic activity variations. Except in the unlikely event that the magnetosphere acts as a `zero-resistance' source of charge, and momentum, etc., we would anticipate, on the basis of these thermosphere--ionosphere model simulations, to see corresponding modulation of magnetosphere--ionosphere forcing as a function of U.T., season and geomagnetic activity. However, a detailed theoretical evaluation of such processes will have to await the development of a new range of coupled models embracing the near-Earth environment. As new experimental data from coordinated ground-based campaigns becomes available over the next several years, and it is to be hoped from new space missions within the next decade, we may hope that the validity of many of the simplified assumptions we currently have to make within present models can be tested. Undoubtedly, many present concepts will be found wanting. The impact of global images of particle precipitation and energy deposition, coupled with perhaps the development of techniques of imaging polar plasma convection patterns will mean that future models are capable of looking at the effects of short period and smaller-scale variations in forcing. The present patterns of magnetospheric forcing are too simplified and averaged in time and space. While the thermosphere averages out rapid and short-scale momentum inputs, the energy input integrates all variations, including the effect of rapid forcing variations. The thermospheric composition responds to this `additional' energy source in a way which presently cannot be simulated accurately, and we already know how sensitive the polar plasma environment appears to be to thermospheric composition changes forced by the combined solar and magnetospheric forcing. We are indebted to Dr Fred Rich for provision of the Heppner & Maynard polar electric fields in the form of harmonic coefficients. We also thank John Harmer and Hilary Hughes for their assistance in preparing, running and processing the computer simulations using the UCL--Sheffield coupled ionospheric--thermospheric model. Computer time was made available by the University of London Computer Centre (CRAY 1-S) and on the CRAY-XMP-48 at the Rutherford Appleton Laboratory (Science and Engineering Research Council). The research was supported by grants from the U.K. SERC, and from the European Office of Aerospace Research and Development (AFOSR-86-341). The IGRF magnetic field model was provided, in computer-readable form, by the British Geological Survey, Edinburgh.

  18. On the Symmetry of Ionospheric Polar Cap Patch Exits Around Magnetic Midnight

    NASA Astrophysics Data System (ADS)

    Moen, J. I.; Hosokawa, K.; Gulbrandsen, N.; Clausen, L.

    2014-12-01

    We present continuous observations of polar cap patches exiting the polar cap ionosphere into the night time auoral oval. Satellite images of the auroral oval and all-sky camera observations of 630.0 nm airglow patches superimposed onto SuperDARN convection maps, reveals a detailed picture on how patches exiting the polar cap and return to the dayside at night, on both the dusk convection cell and the dawn convection cell. We also present eight years of statistics demonstrating that the MLT distribution of patch exits are marginally affected by the IMF BY polarity 3-4 hours around midnight. Synthesizing our observations with previous results there are two, possibly related, explanations to why patches populate both convection cells almost symmetrically. i) Intake of patch material occur on both convection cells for both IMF BY polarities. ii) According to the patch formation model by Lockwood and Carlson et al. [1992] the excitation of flow associated with transient dayside reconnection produces cigar-shaped patches stretching across both the morning and the evening convection cells. Applying the dynamic polar cap flow model by Cowley and Lockwood [1992], we suggest that dawn-dusk elongated patches may be torn apart at night when they are grabbed by transient tail reconnection. The associated twin cell flow disturbance expanding from the reconnection region will divert plasma towards dawn and dusk. This may explain the observed exits on both convection cells.

  19. Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere

    SciTech Connect

    Liu Yu; Cao Jinxiang; Wang Jian; Zheng Zhe; Xu Liang; Du Yinchang

    2012-09-15

    A new approach for investigating ionosphere chemical depletion in the laboratory is introduced. Air glow discharge plasma closely resembling the ionosphere in both composition and chemical reactions is used as the artificially created ionosphere. The ionospheric depletion experiment is accomplished by releasing chemicals such as SF{sub 6}, CCl{sub 2}F{sub 2}, and CO{sub 2} into the model discharge. The evolution of the electron density is investigated by varying the plasma pressure and input power. It is found that the negative ion (SF{sub 6}{sup -}, CCl{sub 2}F{sub 2}{sup -}) intermediary species provide larger reduction of the electron density than the positive ion (CO{sub 2}{sup +}) intermediary species. The negative ion intermediary species are also more efficient in producing ionospheric holes because of their fast reaction rates. Airglow enhancement attributed to SF{sub 6} and CO{sub 2} releases agrees well with the published data. Compared to the traditional methods, the new scheme is simpler to use, both in the release of chemicals and in the electron density measurements. It is therefore more efficient for investigating the release of chemicals in the ionosphere.

  20. Impact of ns-DBD plasma actuation on the boundary layer transition using convective heat transfer measurements

    NASA Astrophysics Data System (ADS)

    Ullmer, Dirk; Peschke, Philip; Terzis, Alexandros; Ott, Peter; Weigand, Bernhard

    2015-09-01

    This paper demonstrates that the impact of nanosecond pulsed dielectric barrier discharge (ns-DBD) actuators on the structure of the boundary layer can be investigated using quantitative convective heat transfer measurements. For the experiments, the flow over a flat plate with a C4 leading edge thickness distribution was examined at low speed incompressible flow (6.6-11.5 m s-1). An ns-DBD plasma actuator was mounted 5 mm downstream of the leading edge and several experiments were conducted giving particular emphasis on the effect of actuation frequency and the freestream velocity. Local heat transfer distributions were measured using the transient liquid crystal technique with and without plasma activated. As a result, any effect of plasma on the structure of the boundary layer is interpreted by local heat transfer coefficient distributions which are compared with laminar and turbulent boundary layer correlations. The heat transfer results, which are also confirmed by hot-wire measurements, show the considerable effect of the actuation frequency on the location of the transition point elucidating that liquid crystal thermography is a promising method for investigating plasma-flow interactions very close to the wall. Additionally, the hot-wire measurements indicate possible velocity oscillations in the near wall flow due to plasma activation.

  1. Theory of imperfect magnetosphere-ionosphere coupling

    SciTech Connect

    Kan, J.R.; Lee, L.C.

    1980-09-01

    A theory of magnetosphere-ionosphere coupling in the presence of field-aligned potential drops is formulated within the framework of magnetohydrodynamic equations. Our formulation allows the magnetosphere as well as the ionosphere to respond self-consistently to the parallel potential drop along auroral field lines. Equipotential contours are distorted into a V-shaped structure near the convection reversal boundary and S-shaped on the equatorward side, each gives rise to an inverted V precipitation band. The loading effect of the imperfect coupling results in a valley in the electric field profile which occurs equatorward of the convection reversal boundary.

  2. 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.

  3. Observations of the Ionospheric Wave Disturbances Using the Kharkov Incoherent Scatter Radar upon RF Heating of the Near-Earth Plasma

    NASA Astrophysics Data System (ADS)

    Chernogor, L. F.; Panasenko, S. V.; Frolov, V. L.; Domnin, I. F.

    2015-07-01

    Characteristics of the wave disturbances of the ionospheric electron number density were measured using the Kharkov incoherent scatter radar. The disturbance generation accompanied the SURA heating of the near-Earth plasma by high-power periodic radiation. The distance between the heater and the radar was about 960 km. The possibility of generating ionospheric wave disturbances with a period of 20 to 30 min in the internal gravity wave range was confirmed. The disturbance propagation velocity was near 320-400 m/s, and the relative amplitude of the electron density variation was 1-10%. The wave disturbances appeared in the altitude range 145-235 km. Aperiodic bursts of the electron number density with a relative amplitude of up to 5-10% were detected after the first switch-ons of periodic radiation in the 30-min heating — 30-min pause regime at altitudes of 145 to 310 km. The observation results generally conform to the synchronous observation data obtained using the Kharkov vertical-sounding Doppler radar and a network of ionosondes.

  4. 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.

  5. 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.

  6. Topside Ionospheric Sounder for CubeSats

    NASA Astrophysics Data System (ADS)

    Swenson, C.; Pratt, J.; Fish, C. S.; Winkler, C.; Pilinski, M.; Azeem, I.; Crowley, G.; Jeppesen, M.; Martineau, R.

    2014-12-01

    This presentation will outline the design of a Topside Ionospheric Sounder (TIS) for CubeSats. In the same way that an ionosonde measures the ionospheric profile from the ground, a Topside Sounder measures the ionospheric profile from a location above the F-region peak. The TIS will address the need for increased space situational awareness and environmental monitoring by estimating electron density profiles in the topside of the ionosphere. The TIS will measure topside electron density profiles for plasma frequencies ranging from 0.89 MHz to 28.4 MHz below the satellite altitude. The precision of the measurement will be 5% or 10,000 p/cm^3. The TIS average power consumption will be below 10 W and a mass of less than 10 kg, so it is appropriate for a 6U Cubesat (or multiple of that size). The sounder will operate via a transmitted frequency sweep across the desired plasma frequencies which, upon reception, can be differenced to determine range and density information of the topside ionosphere. The velocity of the spacecraft necessitates careful balancing of range resolution and frequency knowledge requirements as well as novel processing techniques to correctly associate the return signal with the correct plasma frequency. TIS is being designed to provide a low cost, low mass spacecraft that can provide accurate topside profiles of the ionospheric electron density in order to further understanding of ionospheric structure and dynamic processes in the ionosphere.

  7. 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.

  8. A snapshot of the polar ionosphere. [satellite observation of F layer and topside

    NASA Technical Reports Server (NTRS)

    Whitteker, J. H.; Brace, L. H.; Maier, E. J.; Burrows, J. R.; Dodson, W. H.; Winningham, J. D.

    1976-01-01

    This paper presents a picture of the north polar F layer and topside ionosphere obtained primarily from three satellites (Alouette 2, ISIS 1, ISIS 2) that passed over the region within a time interval of about 50 min on a magnetically quiet day. The horizontal distribution of electron densities at the peak of the F layer is found to be similar to synoptic results from the IGY. Energetic-particle and ionospheric-plasma data are also presented, and the F-layer data are discussed in terms of these measurements as well as in terms of electric-field and neutral N2 density measurements made by other satellites on other occasions. The major feature observed is a tongue of F-region ionization extending from the dayside across the polar cap, which is accounted for by antisunward drift due to magnetospheric convection. In the F layer and topside ionosphere, the main effect of auroral precipitation appears to be heating and expansion of the topside. A region of low F-layer density appears on the morning side of the polar cap, which may be due to convection and possibly also to enhanced N2 densities.

  9. HF Radar for Long-Range Monitoring of Ionospheric Irregularities in the Equatorial Region

    NASA Astrophysics Data System (ADS)

    Pedersen, T. R.; Parris, R. T.; Dao, E. V.

    2014-12-01

    Ionospheric instabilities associated with plasma bubbles in the equatorial region are one of the major space weather impacts, creating scintillation that affects satellite communications and navigation as well as spread-F and propagation effects on lower frequency systems. Coherent scatter radars can be used to detect the presence of irregularities at a scale size corresponding to half the wavelength of the radar when the raypaths are perpendicular to the magnetic field. A number of vertical incidence radars operating in the VHF range near the magnetic equator use this effect to map out vertical irregularity structure in bubbles, while at high latitudes in both the northern and more recently southern hemisphere, HF radars in the SuperDARN network have successfully used refraction along near-horizontal paths to reach perpendicularity with the near-vertical magnetic field and map out ionospheric convection and irregularity structure over fields of view thousands of km across. In the equatorial region, perpendicularity can be obtained anywhere within a near-vertical plane even without refraction, although refraction can be used to achieve long ranges after one or more reflections from the earth's surface and bottomside ionosphere. This potentially provides a means of detecting and monitoring equatorial plasma bubbles over the oceans from long ranges using a small number of ground-based sites. We discuss the possible echoes that could be detected by such a system, the likely propagation modes and characteristics, and means of obtaining and utilizing elevation angle information to correctly locate distant plasma bubbles.

  10. Magnetosphere-ionosphere/thermosphere coupling: Self-consistent solutions for a one-dimensional stratified ionosphere in three-fluid theory

    NASA Astrophysics Data System (ADS)

    Song, P.; Vasyli?nas, V. M.; Zhou, X.-Z.

    2009-08-01

    We study the local response of a model ionosphere to a change in the magnetospheric convection, on the basis of a three-fluid (electrons, ions, and neutrals) approach to describing the dynamic processes of solar wind-magnetosphere-ionosphere/thermosphere coupling. The physical description, including the three-fluid generalized Ohm's law, the plasma momentum equation, and the neutral momentum equation, as well as Maxwell's equations, takes into account electromagnetic coupling among the charged species and collisions among the three species; the geometrical configuration in this initial study, however, is highly simplified and approximates a localized region within the polar cap. We model the driver of the convection by a changing tangential flow of plasma, imposed at the top boundary of the ionosphere, and follow numerically the self-consistent evolution of the entire system, which is assumed to be incompressible. A magnetic field distortion, corresponding to a horizontal (not field-aligned) current, propagates from the magnetosphere to the lower ionosphere, producing at first a strong transient Pedersen current which then decreases to a steady state value. The transient time for the system to settle downscales as the Alfvn-wave travel time between the E layer and the top boundary (verified by redoing the calculations with different heights of the upper boundary). Large perturbations occur during the first 10 Alfvn travel times, and it takes about 20 Alfvn travel times for the system to reach a quasi steady state. After the quasi steady state has been reached, the neutral wind continues to vary slowly (forces due to neutral pressure and effective viscosity have been neglected). When magnetospheric convection is reversed after 1 h, an overshoot of the Pedersen current occurs before the system settles into a new quasi steady state. The electrostatic approximation commonly used in the magnetosphere-ionosphere coupling models remains poor for up to 10 Alfvn travel times (which could translate to more than 15 min in a more realistic geometry); the assumption that the neutrals remain at rest relative to the Earth is poor within the F layer.

  11. Disturbance Effects Seen in the Midlatitude Ionosphere with SuperDARN

    NASA Astrophysics Data System (ADS)

    Ruohoniemi, J. M.; Baker, J. B. H.; Bristow, W. A.; Shepherd, S. G.; Miller, E. S.

    2014-12-01

    With the construction of the first midlatitude SuperDARN radar at NASA Wallops Flight Facility in 2005 it quickly became apparent that much activity can be observed in the midlatitude ionosphere even outside of large storm intervals. Over the last five years a chain of SuperDARN radars has been deployed at midlatitudes under the NSF Mid-Sized Infrastructure program that extends across the western hemisphere as far as east Asia. The new radars are providing unprecedented large-scale views of disturbance effects such as the storm-time expansion of auroral flows, subauroral polarization streams (SAPS), and travelling ionospheric disturbances (TIDs). When combined with large-scale mapping of GPS/TEC it is possible to observe directly the generation of plasma structures such as storm-enhanced density features (SEDs), tongues of ionization (TOIs), and polar cap patches, and to understand their dependence on the dynamic convection pattern reaching to the mid-latitude region. One unexpected result is the observation of backscatter from irregularities distributed throughout the quiet-time nightside subauroral ionosphere. This phenomenon gives us views of electric fields that are conjugate to the inner magnetosphere and also reveals the occurrence of large transients in the quiet-time subauroral electric fields. In this talk we summarize over the effects identified to date and discuss the insights gained in understanding the disturbed midlatitude ionosphere.

  12. Observations of ionosphere/magnetosphere interactions from the Dynamics Explorer satellites

    NASA Technical Reports Server (NTRS)

    Hoffman, R. A.

    1989-01-01

    The Dynamics Explorer program was a dual spacecraft mission designed to study the interactions between the upper atmosphere, ionosphere and magnetosphere. The global auroral images acquired from the high altitude spacecraft have provided a revolutionary new time-dependent frame of reference for the interpretation of data acquired in situ. Using data especially from the low altitude spacecraft, interrelationships are developed between the various electrodynamic parameters measured. Ionospheric irregularities are found to be especially intense in regions of electric field convection shears, which are closely related to the dusk hemisphere field-aligned currents. These region 1 currents are spatially connected to the boundary plasma sheet electron precipitation. At all local times, there appears to be a universal relationship between regions where div E is less than 0 and electron precipitation structures. Depending upon the characteristics of the electrons bombarding the atmosphere, the atmosphere will radiate various spectral optical emissions, which can be imaged from high above the polar caps, with temporal resolution sufficient to follow the time-dependent evolution of a substorm. It is concluded that with further detailed analyses of the electrodynamic parameters obtained from in situ measurements, analyses of auroral images will yield specific information on many of the important ionospheric parameters over an entire auroral oval and polar cap, including regions of intense ionospheric irregularities.

  13. Dayside midlatitude ionospheric response to storm time electric fields: A case study for 7 September 2002

    NASA Astrophysics Data System (ADS)

    David, M.; Sojka, J. J.; Schunk, R. W.; Liemohn, M. W.; Coster, A. J.

    2011-12-01

    With the storm of 7-8 September 2002 as a study case, we demonstrate that an ionospheric model driven by a suitable storm time convection electric field can reproduce the F region dayside density enhancements associated with the ionospheric storm positive phase. The ionospheric model in this case is the Utah State University Time Dependent Ionospheric Model (TDIM); the electric field model is the University of Michigan's Hot Electron and Ion Drift Integrator (HEIDI). Extensive ground truth is available throughout the study period from two independent sources: ground-based vertical TEC and ionosonde stations; our simulation results are in good agreement with these observations. We address the question of what is the source of the high-density plasma that is seen during the positive storm phase and show that in this case a magnetospheric electric field with an eastward component that penetrates to midlatitudes increases local production on the dayside to a degree that is sufficient to account for the storm time density increases that have been observed.

  14. 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.

  15. Two-dimensional Ionospheric Flow Pattern Associated with Auroral Streamers

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Zesta, E.; Lyons, L. R.; Yang, J.; Boudouridis, A.; Ge, Y. S.; Ruohoniemi, J. M.; Mende, S. B.

    2011-12-01

    We present direct flow observations and auroral images from the SuperDARN radar and IMAGE WIC imager to investigate the ionospheric flow pattern associated with auroral streamers. For all four cases studied, streamers were ejected from east-west (EW) arcs that initiated from bead-like or small-scale auroral intensifications around the auroral poleward boundary. We find a vortex-like flow pattern with clockwise sense surrounding both the initial auroral forms and the ensuing streamers. The initial eastward flows poleward of the auroral forms and westward flows equatorward of the forms evolved to be roughly equatorward within and to the east of the streamers, and primarily poleward or toward a more poleward direction to the west of the streamers. We also found in three cases signatures of flow bifurcations at the equatorward end of the streamers, which suggests a double vortex-like flow pattern with the counterclockwise one further east of the clockwise one. Our results are consistent with the double-vortex flow structure due to interchange convection associated with a plasma sheet bubble predicted by different numerical simulations, and also provide solid evidence to several previous studies, especially Sergeev et al. [2004]. This indicates that the observed flow pattern may be the ionospheric manifestation of interchange instability in the plasma sheet.

  16. 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

  17. Historical overview of HF ionospheric modification research

    NASA Astrophysics Data System (ADS)

    Gordon, William E.; Duncan, Lewis M.

    1990-10-01

    Radio waves have inadvertently modified the Earth's ionospher since the Luxembourg observations of Tellegen in 1933 and perhaps since Marconi in 1901. The history of ionospheric modification by radio waves is reviewed, beginning with Marconi, describing the Luxembourg effect and its explanations, and its early use to deduce the properties of the lower ionosphere in the 1930s. The measurements became more sophisticated in the 1950s, leading to the call for high-power high-frequency modification experiments in the upper ionosphere. Beginning in 1970, radio facilities became available of sufficient powers to induce changes in the ionospheric plasma detectable by a wide array of diagnostic instruments and techniques. A summary of these effect is presented based upon work up to 1990. These studies were originally motivated as a means of better understanding the natural ionosphere using a weak perturbational approach. However, a rich spectrum of nonlinear wave-plasma interactions was quickly discovered and ionospheric modifications research became strongly motivated by issues in basic plasma physics. The ionosphere and near-Earth space are now exploited as an exceptional plasma laboratory-without-walls for the study of fundamental plasma processes requiring large spatial or temporal scales. A brief overview of these processes and phenomena is presented, illustrated using results obtained from the Arecibo ionospheric modification facilities. The lessons learned and phenomena explored thus far offer many opportunities for controlling the ionospheric environment critical to many civilian and military telecommunications systems, both to disrupt systems normally operational and to create new propagation paths otherwise unavailable.

  18. Ionospheric imaging in Africa

    NASA Astrophysics Data System (ADS)

    Chartier, Alex T.; Kinrade, Joe; Mitchell, Cathryn N.; Rose, Julian A. R.; Jackson, David R.; Cilliers, Pierre; Habarulema, John-Bosco; Katamzi, Zama; Mckinnell, Lee-Anne; Matamba, Tshimangadzo; Opperman, Ben; Ssessanga, Nicholas; Giday, Nigussie Mezgebe; Tyalimpi, Vumile; Franceschi, Giorgiana De; Romano, Vincenzo; Scotto, Carlo; Notarpietro, Riccardo; Dovis, Fabio; Avenant, Eugene; Wonnacott, Richard; Oyeyemi, Elijah; Mahrous, Ayman; Tsidu, Gizaw Mengistu; Lekamisy, Harvey; Olwendo, Joseph Ouko; Sibanda, Patrick; Gogie, Tsegaye Kassa; Rabiu, Babatunde; Jong, Kees De; Adewale, Adekola

    2014-01-01

    ionospheric specification is necessary for improving human activities such as radar detection, navigation, and Earth observation. This is of particular importance in Africa, where strong plasma density gradients exist due to the equatorial ionization anomaly. In this paper the accuracy of three-dimensional ionospheric images is assessed over a 2 week test period (2-16 December 2012). These images are produced using differential Global Positioning System (GPS) slant total electron content observations and a time-dependent tomography algorithm. The test period is selected to coincide with a period of increased GPS data availability from the African Geodetic Reference Frame (AFREF) project. A simulation approach that includes the addition of realistic errors is employed in order to provide a ground truth. Results show that the inclusion of observations from the AFREF archive significantly reduces ionospheric specification errors across the African sector, especially in regions that are poorly served by the permanent network of GPS receivers. The permanent network could be improved by adding extra sites and by reducing the number of service outages that affect the existing sites.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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 = A s 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.

  20. 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.

  1. 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.

  2. Space weather challenges of the polar cap ionosphere

    NASA Astrophysics Data System (ADS)

    Moen, Jøran; Oksavik, Kjellmar; Alfonsi, Lucilla; Daabakk, Yvonne; Romano, Vineenzo; Spogli, Luca

    2013-01-01

    This paper presents research on polar cap ionosphere space weather phenomena conducted during the European Cooperation in Science and Technology (COST) action ES0803 from 2008 to 2012. The main part of the work has been directed toward the study of plasma instabilities and scintillations in association with cusp flow channels and polar cap electron density structures/patches, which is considered as critical knowledge in order to develop forecast models for scintillations in the polar cap. We have approached this problem by multi-instrument techniques that comprise the EISCAT Svalbard Radar, SuperDARN radars, in-situ rocket, and GPS scintillation measurements. The Discussion section aims to unify the bits and pieces of highly specialized information from several papers into a generalized picture. The cusp ionosphere appears as a hot region in GPS scintillation climatology maps. Our results are consistent with the existing view that scintillations in the cusp and the polar cap ionosphere are mainly due to multi-scale structures generated by instability processes associated with the cross-polar transport of polar cap patches. We have demonstrated that the SuperDARN convection model can be used to track these patches backward and forward in time. Hence, once a patch has been detected in the cusp inflow region, SuperDARN can be used to forecast its destination in the future. However, the high-density gradient of polar cap patches is not the only prerequisite for high-latitude scintillations. Unprecedented high-resolution rocket measurements reveal that the cusp ionosphere is associated with filamentary precipitation giving rise to kilometer scale gradients onto which the gradient drift instability can operate very efficiently. Cusp ionosphere scintillations also occur during IMF BZ north conditions, which further substantiates that particle precipitation can play a key role to initialize plasma structuring. Furthermore, the cusp is associated with flow channels and strong flow shears, and we have demonstrated that the Kelvin-Helmholtz instability process may be efficiently driven by reversed flow events.

  3. Ionospheric redistribution during geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Immel, T. J.; Mannucci, A. J.

    2013-12-01

    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.

  4. 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.

  5. 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.

  6. Approaches to ionospheric modelling, simulation and prediction

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    The ionosphere is a complex, multispecies, anisotropic medium that exhibits a significant variation with time, space, season, solar cycle, and geomagnetic activity. In recent years, a wide range of models have been developed in an effort to describe ionospheric behavior. The modeling efforts include: (1) empirical models based on extensive worldwide data sets; (2) simple analytical models for a restricted number of ionospheric parameters; (3) comprehensive, 3D, time-dependent models that require supercomputers; (4) spherical harmonic models based on fits to output obtained from comprehensive numerical models; and (5) ionospheric models driven by real-time magnetospheric inputs. In an effort to achieve simplicity, some of the models have been restricted to certain altitude or latitude domains, while others have been restricted to certain ionospheric parameters, such as the F-region peak density, the auroral conductivity, and the plasma temperatures. The current status of the modeling efforts is reviewed.

  7. 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.

  8. MLT Asymmetries in the Magnetospheric Wave Distribution and Their Effect on Ionospheric Conductivity and Global Transport

    NASA Astrophysics Data System (ADS)

    Thorne, R. M.; Li, W.; Bortnik, J.; Ni, B.; Jordanova, V.; Kletzing, C.; Kurth, W. S.; Hospodarsky, G. B.; Angelopoulos, V.

    2014-12-01

    Diffuse auroral precipitation is the major source of ionospheric conductivity at high latitudes, and the resulting global distribution of enhanced conductivity affects the penetration of magnetospheric electric fields and plasma transport into the inner magnetosphere. Recent work has demonstrated that diffuse auroral precipitation is caused by resonant scattering of plasma sheet electrons due to a combination of both electrostatic electron cyclotron harmonic waves and electromagnetic whistler mode chorus emissions. Each class of wave is excited, predominantly on the dawn side of the magnetosphere, following the convective injection and gradient drifting of plasma sheet electrons into the inner magnetosphere. During geomagnetically active periods, the resultant electron scattering can approach the limit of strong diffusion, and the timescale for scattering loss into the atmosphere becomes shorter than the time for transport of plasma to the dayside. This leads to a pronounced day/night asymmetry in the diffuse auroral precipitation and a localized enhancement in conductivity in the post midnight sector. Quantifying the rate of diffuse auroral scattering by each class of wave is therefore imperative for understanding the global distribution of enhanced ionospheric conductivity and its non-linear feedback on plasma transport in the inner magnetosphere. Recent attempts to model the observed global distribution of waves and the associated pattern of electron precipitation will be discussed.

  9. Initial results from a dynamic coupled magnetosphere-ionosphere-ring current model

    NASA Astrophysics Data System (ADS)

    Pembroke, Asher; Toffoletto, Frank; Sazykin, Stanislav; Wiltberger, Michael; Lyon, John; Merkin, Viacheslav; Schmitt, Peter

    2012-02-01

    In this paper 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) and report some results 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-β ≤ 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.

  10. 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.

  11. 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.

  12. 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 an ionospheric phenomenon attributed to tsunami, termed tsunamigenic ionospheric hole (TIH) [Kakinami and Kamogwa et al., GRL, 2012]. After the TEC depression accompanying a monoperiodic variation with approximately 4-minute period as an acoustic resonance between the ionosphere and the solid earth, the TIH gradually recovered. In addition, geomagnetic pulsations with the periods of 150, 180 and 210 seconds were observed on the ground in Japan approximately 5 minutes after the mainshock. Since the variation with the period of 180 seconds was simultaneously detected at the magnetic conjugate of points of Japan, namely Australia, field aligned currents along the magnetic field line were excited. The field aligned currents might be excited due to E and F region dynamo current caused by acoustic waves originating from the tsunami. This result implies that a large earthquake generates seismogenic field aligned currents. Furthermore, monoperiodical geomagnetic oscillation pointing to the epicenter of which velocity corresponds to Rayleigh waves occurs. This may occur due to seismogenic arc-current in E region. Removing such magnetic oscillations from the observed data, clear tsunami dynamo effect was found. This result implies that a large EQ generates seismogenic field aligned currents, seismogenic arc-current and tsunami dynamo current which disturb geomagnetic field. Thus, we found the complex coupling process between a large EQ and an ionosphere from the results of Tohoku EQ.

  13. Current-driven plasma waves in the Versatile Toroidal Facility (VTF)

    SciTech Connect

    Moriarty, D.T.; Lee, M.C.; Riddolls, R.J.; Murphy, S.M.; Rowlands, M.J.

    1995-12-31

    The authors have been conducting laboratory experiments to investigate plasma turbulence that can affect the propagation of electromagnetic waves. This work is aimed at simulating the ionospheric plasma turbulence and cross-checking the radar experiments at Arecibo, Puerto Rico. The large toroidal plasma device, called the Versatile Toroidal Facility (VTF), can produce a radially inhomogeneous plasma imposed in a helically shaped magnetic field. VTF plasma has a sharp density gradient and an intense magnetic field-aligned current, simulating well the plasma environment in the auroral ionosphere. A broad spectrum of plasma waves can be exited in VTF by the injected microwaves and electron beams. In this paper, the authors discuss the excitation of low-frequency plasma waves driven by electric currents, including ion acoustic waves and current-convective modes. A good agreement has been found between the experimental results and the theories developed for the VTF plasmas. However, their experimental results are quite different from those obtained in the rocket/space shuttle experiments. The difference in the laboratory experiments and space experiments arise form two facts. One is that the plasma inhomogeneity does not play a significant role in the space experiments. The other is that the electron beam injected in the space experiments does not produce a drifting Maxwellian plasma as seen in the VTF plasmas. The contrast between the VTF experiments and the active space experiments show that VTF can adequately simulate the ionospheric plasma turbulence and complement the rocket/space shuttle experiments.

  14. Ray trace calculation of ionospheric propagation at lower frequencies

    NASA Astrophysics Data System (ADS)

    Reilly, Michael H.

    2006-10-01

    The Raytrace/Ionospheric Conductivity and Electron Density-Bent-Gallagher model has been revised to make it applicable to ionospheric propagation at low radio frequencies (0.5-5.0 MHz), where the ionosphere and magnetic anisotropy drastically alter propagation paths and provide a severe test of propagation model algorithms. The necessary revisions are discussed, and the model is applied to the problem of ionospheric penetration from a source below the ionosphere to a receiver above the ionosphere. It is necessary to include the electron collision frequency in the Appleton-Hartree index of refraction in order to permit ionospheric penetration for radio frequencies below the maximum plasma frequency (e.g., whistler modes). The associated reformulation of the ray trace equations for a complex index of refraction is straightforward. Difficulties with numerical methods are cited for the lowest frequencies, and future improvements are indicated.

  15. 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.

  16. Comparative study of Mars and Venus ionospheres using ionospheric photoelectron measurements by Mars and Venus Express

    NASA Astrophysics Data System (ADS)

    Molaverdikhani, K.; Brain, D. A.

    2013-12-01

    The Analyser of Space Plasmas and Energetic Atoms (ASPERA-4) instrument package on Venus Express (VEX) has a nearly identical counterpart on Mars Express, called ASPERA-3, which provides a unique opportunity to study the Venus and Mars ionospheres with minimal instrumental interpretation side effects. Previously we used the Electron Spectrometer (ELS) on ASPERA-4 to study the structure and variability of the Venus ionosphere, which is of interest for both plasma escape and the dynamics of the neutral upper atmosphere. We discovered a dawn-dusk asymmetry in the Venus ionosphere, uncorrelated with Interplanetary Magnetic Field strength or direction. Here, we have adapted an automatic algorithm (filter) from this previous work to detect the presence of photoelectrons near Mars in ASPERA-3 ELS data. With information about ionospheric photoelectrons at both Venus (> 6 years of data) and Mars (~9 years of data), we are able to directly compare the ionospheres of the two planets. The filter has identified approximately 200,000 and 3 million measurements at Venus and Mars, respectively, that contain significant photoelectron peaks in the range of 20-30 eV. We find that the Martian ionosphere is more extended vertically in comparison to the Venus ionosphere, relative to the planet's radius. Relative to Venus, the Mars ionosphere is denser in sunlight, less abundant in eclipse, and has a larger tailward extent. The Mars ionosphere also responds to external drivers, such as solar EUV intensity, differently than the Venus ionosphere. We present some plausible ideas to explain these differences based on photoionization and plasma transport mechanisms, and differences in external conditions at the two planets.

  17. IMF-By dependence of transient ionospheric flow perturbation associated with sudden impulses: SuperDARN observations

    NASA Astrophysics Data System (ADS)

    Hori, Tomoaki; Shinbori, Atsuki; Fujita, Shigeru; Nishitani, Nozomu

    2015-12-01

    A statistical study using a large dataset 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 depending on the combination of the polarity of SI and interplanetary magnetic field (IMF)-By. Detailed statistics of the SuperDARN observations reveal that the dawn-dusk asymmetry of flow vortices due to IMF-By appears during negative SIs, while such asymmetric characteristics are not seen during positive SIs. 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.

  18. Negative ion and dust grain charge in Titan's ionosphere: multi-instrument case study

    NASA Astrophysics Data System (ADS)

    Shebanits, O.; Wahlund, J.-E.; Edberg, N. J. T.; Wellbrock, A.; Coates, A. J.; Crary, F.; Andrews, D.

    2014-04-01

    The Cassini s/c in-situ plasma measurements of Titan's ionosphere by Radio and Plasma Wave Science (RPWS) Langmuir Probe (LP), Cassini Plasma Spectrometer (CAPS) Electron (ELS) and Ion Beam (IBS) spectrometers are combined for selected flybys (T16, T20, T29, T40 and T56) to further constrain plasma parameters of ionosphere below 1400 km.

  19. 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 the other plate.

  20. Factors in quantifying the ionosphere as a mass source for the magnetosphere

    NASA Astrophysics Data System (ADS)

    Kintner, P. M.; Lynch, K.

    2008-05-01

    There is a growing consensus that heavy ions in the magnetosphere affect geomagnetic activity, convection, and reconnection. The O+ fraction in the ring current is known to grow during magnetic activity and dominates during geomagnetic storms. During substantial magnetic activity molecular ions are also observed in the topside ionosphere and magnetosphere with fluxes the order of 0.10 of the O+ fluxes. Despite these observations how heavy ions escape the ionosphere is not clear. For example O+ charge exchanges with H and molecular ions exist only in the E-region and lower F-region. There are a limited number of mechanisms producing upward fluxes of heavy ions in the topside ionosphere. In the F-region soft electron precipitation can increase the temperature and scale height of the electron gas leading to expansion, an ambipolar electric field and upflowing ions (Type II). Likewise increased convection can heat the ion gas leading to an increase in scale height and upflowing ions (Type I). In both cases when the heat source is removed, ions flow downward. At overlapping and somewhat higher altitudes upward heavy ion fluxes are also associated with transverse ion acceleration (TIA) which in turn is primarily associated with an observation called BBELF (broad band extra low frequency) waves. How these three mechanisms interact is not yet quantified. For example a two step process of heat generated upflow followed by TIA to generate outflow is one model. There are reasons to suggest that this two-step and altitude dependent model may be misleading. For example if BBELF is generated by a current driven instability, it is more likely to occur in low density regions and moving more plasma density to higher altitudes is irrelevant. If the BBELF is driven by the phase mixing of dispersive Alfven waves on steep horizontal density gradients, then the Type I or Type II uplift of the ionosphere would tend to remove the gradients through thermal inertia. On the other hand for O+ to not charge exchange with H, the BBELF process may need to work at higher altitudes and lower thermospheric H densities and would be benefit from ionospheric uplift. Combining rocket and radar observations can help address how these heavy ion fluxes are transported to higher altitudes or escape velocities. For example the ISR radar observations yield large data bases at low altitudes while sounding rockets probe the space detailed fine-scale kinetic environment above the fluid regime. One goal of this combination is to provide the lower boundary conditions for multiple-fluid ionospheric- magnetospheric coupling models.

  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 formation of the TOI.

  2. 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.

  3. Equatorial ionosphere 'fountain- effect' above imminent earthquake epicenter

    NASA Astrophysics Data System (ADS)

    Ruzhin, Yu.; Depueva, A. H.; Devi, M.

    2003-04-01

    Existence of lithosphere-ionosphere interaction is known for a long time, but it does not mean that the ionospheric morphology above areas of earthquakes preparation is investigated sufficiently well. It was shown that seismo-precursor variations of the atmosphere electricity cause appropriate electric field at the ionospheric heights, which being added to existing natural field may both increase or decrease its action on the ionospheric plasma characteristics: drifts, aeronomy, plasma chemistry, ion composition etc. Anomalous variations appear inside whole ionosphere volume from the lowest boundary of Earth's plasma shell (100 km) up to 1000km and higher. Under fortunate coincidence seismo-precursor electric field can generate natural ionosphere phenomena, 'fountain- effect', leading to Appleton anomaly in the equatorial ionosphere over future earthquake position. Our basic idea is to take into account dependence of the observable effects on a geographical position of the earthquake epicenter. As for low latitudes it is proved by specificity of formation and dynamics of equatorial ionosphere (seismogenic ""fountain" effect , first of all), and also by features of earth crust structure close to the equator (mainly meridionally alongated tectonic faults). Ionospheric effects of low-latitude earthquakes were not investigated separately so far though rather semo-active zones are located namely at low latitudes: India, Peru, Oceania. We used the data of topside sounding of ALOUETTE-1 and ISS-b satellites, and also data of ground-based vertical sounding stationary stations Kodaikanal, Huancayo, Djibouti etc. and records of the total electron content (TEC).

  4. 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

  5. Alfvén wave characteristics of equatorial plasma irregularities in the ionosphere derived from CHAMP observations

    NASA Astrophysics Data System (ADS)

    Lühr, Hermann; Park, Jaeheung; Xiong, Chao; Xiong, Chao; Rauberg, Jan

    2014-08-01

    We report magnetic field observations of the components transverse to the main field in the frequency range 1-25 Hz from times of equatorial plasma irregularity crossings. These field variations are interpreted as Alfvénic signatures accompanying intermediate-scale (150 m - 4 km) plasma density depletions. Data utilized are the high-resolution CHAMP magnetic field measurements sampled at 50 Hz along the north-south satellite track. The recorded signals do not reflect the temporal variation but the spatial distribution of Alfvénic signatures. This is the first comprehensive study of Alfvénic signatures related to equatorial plasma bubbles that covers the whole solar cycle from 2000 to 2010. A detailed picture of the wave characteristics can be drawn due to the large number (almost 9000) of events considered. Some important findings are: Alfvénic features are a common feature of intermediate-scale plasma structures. The zonal and meridional magnetic components are generally well correlated suggesting skewed current sheets. The sheets have an orientation that is on average deflect by about 32° away from magnetic east towards upward or downward depending on the hemisphere. We have estimated the Poynting flux flowing into the E region. Typical values are distributed over the range 10-8 - 10-6 W/m2. Large Poynting fluxes are related to steep spectra of the Alfvénic signal, which imply passages through regularly varying electron density structures. No dependence of the Poynting flux level on solar activity has been found. But below a certain solar flux value (F10.7 < 100 sfu) practically no events are detected. There is a clear tendency that large Poynting flux events occur preferably at early hours after sunset (e.g. 20:00 local time). Towards later times the occurrence peak shifts successively towards lower energy levels. Finally we compare our observations with the recently published results of the high-resolution 3-D model simulations by Dao et al. (2013).

  6. LIFDAR: A Diagnostic Tool for the Ionosphere

    NASA Astrophysics Data System (ADS)

    Kia, O. E.; Rodgers, C. T.; Batholomew, J. L.

    2011-12-01

    ITT Corporation proposes a novel system to measure and monitor the ion species within the Earth's ionosphere called Laser Induced Fluorescence Detection and Ranging (LIFDAR). Unlike current ionosphere measurements that detect electrons and magnetic field, LIFDAR remotely measures the major contributing ion species to the electron plasma. The LIFDAR dataset has the added capability to demonstrate stratification and classification of the layers of the ionosphere to ultimately give a true tomographic view. We propose a proof of concept study using existing atmospheric LIDAR sensors combined with a mountaintop observatory for a single ion species that is prevalent in all layers of the atmosphere. We envision the LIFDAR concept will enable verification, validation, and exploration of the physics of the magneto-hydrodynamic models used in ionosphere forecasting community. The LIFDAR dataset will provide the necessary ion and electron density data for the system wide data gap. To begin a proof of concept, we present the science justification of the LIFDAR system based on the model photon budget. This analysis is based on the fluorescence of ionized oxygen within the ionosphere versus altitude. We use existing model abundance data of the ionosphere during normal and perturbed states. We propagate the photon uncertainties from the laser source through the atmosphere to the plasma and back to the collecting optics and detector. We calculate the expected photon budget to determine signal to noise estimates based on the targeted altitude and detection efficiency. Finally, we use these results to derive a LIFDAR observation strategy compatible with operational parameters.

  7. 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.

  8. 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.

  9. Observations of solar-wind-driven modulation of the dayside ionospheric DPY current system

    SciTech Connect

    Clauer, C.R.; Miller, P.M.; Sitar, R.J.

    1995-05-01

    The authors report here a collection of complementary measurement near local magnetic noon of a unique ionospheric convection variation observed by the Sondrestrom radar which is related to a nearly periodic variation ({approx} 25-30 min period) in the interplanetary magnetic field B{sub y} component. The authors observe also a poleward phase propagation of magnetic pulsations over a region limited in longitude and latitude near the dayside polar cusp. A series of poleward propagating radio absorption enhancements are observed in the Greenland and South Pole imaging riometer data. The pulsations and absorption enhancements are associated with latitudinally narrow and longitudinally limited intensifications of the westward convection and associated eastward Hall current, which propagates poleward over the magnetometers and radar field of view. For the cases presented the interplanetary B{sub z} is strongly negative, while the ionospheric variations are associated with the low-frequency component of variations in the interplanetary B{sub y} component. In contrast to the previously discovered traveling convection vortices, these features exhibit a poleward phase motion rather than one along lines of invariant latitude. The propagation velocity is slower ({approx} 0.5 - 1.0 km/s) and the structures cover 2 to 3 hours of local time. The authors interpret the observations as a poleward propagation of the DPY current system intensification associated with enhancements in the IMF B{sub y} component. Their observations indicate that the DPY field-aligned current system is propagating poleward and may be moving independent of the convection motion of the plasma and associated field lines. 51 refs., 14 figs., 1 tab.

  10. 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.

  11. 25 Years of Ionospheric Modification with the Space Shuttle

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.

    2011-12-01

    The ionosphere is a low temperature (0.1 eV) plasma layer that surrounds the Earth and affects a wide range of radio systems that involve communications, navigation, and radar. The unmodified ionosphere is in an equilibrium state defined by the balance of production, transport and loss of plasma. The modified ionosphere responds to neutral gas injections with (1) the generation and propagation of plasma waves and (2) the production of plasma irregularities. A single 10 second burn of the on-orbit engines on the Space Shuttle injects 1 GJoule of energy into the upper atmosphere. Injection of hypersonic exhaust vapors from rocket engines pushes the ionosphere out of its equilibrium to yield 20 eV ion beams, launch both neutral and plasma waves, and trigger several instability processes. A wide range of optical emissions, plasma density fluctuations, enhanced temperatures, and changes in composition may be detected during these experiments. Multiple sensors such as instrumented satellites, ground radars, and ground optical instruments are used to determine the extent and lifetime for ionospheric modification. This presentation will focus on experimental data and theoretical discussions of the Space Shuttle Orbital Maneuver Subsystem (OMS) Engines used to modify the upper atmosphere from 1985 to the present. Artificial disturbances in the ionosphere produced by OMS burns have two applications. First, the artificial modification of the ionosphere can provide some control on the radio propagation environment. Second, the man-made disturbances are being produced as proxies to natural disturbances.

  12. 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

  13. On a possible seismomagnetic effect in the topside ionosphere

    NASA Astrophysics Data System (ADS)

    Hegai, V. V.; Kim, V. P.; Liu, J. Y.

    2015-10-01

    In this paper we present the results of the computation of the electric and magnetic fields produced in the ionosphere by the near-earth seismogenic disturbance in the vertical atmospheric electrostatic field under different ionospheric conditions. It is shown that in the nighttime ionosphere during solar minimum and inside large-scale plasma bubbles, the magnitude of the transverse electric field can attain ?0.2 and 1.0 mV/m, respectively. The seismomagnetic effect with the magnitude of ?13 pT is predicted in the topside daytime and nighttime ionosphere at any solar activity.

  14. HF-driven currents in the polar ionosphere

    NASA Astrophysics Data System (ADS)

    Papadopoulos, K.; Gumerov, N. A.; Shao, X.; Doxas, I.; Chang, C. L.

    2011-06-01

    Polar ionospheric heaters have generated ULF/ELF/VLF waves by modulating the auroral electrojet at D/E region altitudes. We present theoretical/computational results indicating that modulated F-region HF heating can generate ionospheric currents even in the absence of electrojet currents. The ELF currents are driven in a two-step process. First, the pressure gradient associated with F-region electron heating drives a local diamagnetic current. This acts as an antenna to inject Magneto-Sonic (MS) waves in the ionospheric plasma. Second, the electric field of the magneto-sonic wave drives Hall currents when it reaches the E region of the ionosphere. The Hall currents act as a secondary antenna that injects waves in the Earth-Ionosphere Waveguide below and Shear Alfven waves upwards to the conjugate regions. The paper examines the scaling and limitations of the concept and suggests proof-of-principle experiments using the HAARP ionospheric heater.

  15. Plasma drifts and polarization electric fields associated with TID-like disturbances in the low-latitude ionosphere: C/NOFS observations

    NASA Astrophysics Data System (ADS)

    Huang, Chao-Song

    2016-02-01

    Medium-scale traveling ionospheric disturbances are often observed at the magnetically conjugate points in the nighttime midlatitude ionosphere. It has been suggested that gravity waves disturb the ionosphere and induce electric fields in one hemisphere and that the electric fields are amplified by the Perkins instability and transmitted along the geomagnetic field lines to the conjugate ionosphere, creating similar disturbances there. However, direct observations of electric fields associated with traveling ionospheric disturbances (TIDs) are very few. In this study, we present low-latitude TID-like disturbances observed by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. It is found that ion velocity perturbations are generated in the directions parallel and perpendicular to the geomagnetic field within TIDs. Both the parallel and perpendicular ion velocity perturbations show an in-phase correlation with the ion density perturbations. For nighttime TIDs, the amplitude of both the parallel and meridional ion velocity perturbations increases almost linearly with the amplitude of the ion density perturbations, and the meridional ion drift is proportional to the parallel ion velocity. For daytime TIDs, the parallel ion velocity perturbation increases with the ion density perturbation, but the meridional ion velocity perturbation does not change much. The observations provide evidence that polarization electric field is generated within TIDs at low latitudes and maps along the geomagnetic field lines over a large distance.

  16. 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.

  17. Characteristics of E-region background ionosphere and plasma waves measured over the dip equator during total solar eclipse campaign

    NASA Astrophysics Data System (ADS)

    Sekar, R.; Gupta, S. P.; Chakrabarty, D.

    2014-07-01

    A unique set of rocket flight measurements of plasma parameters from the dip equator (Thumba; 8.5°N, 76.5°E, dip 0.5°S) was carried out at two obscuration levels (40% and 72%) on a total solar eclipse day (16 February 1980) which was also under a moderately disturbed geomagnetic condition. The path of totality was 400 km north of Thumba. Another rocket flight was conducted on 17 February 1980 to obtain the control day measurement at the same local time. As expected, the electron densities are found to be less throughout the measured altitude region on a solar eclipse day with the 72% obscuration level compared to the control day at the same local time (same solar zenith angle). In the presence of average electron density scale length of 10 and 9 km in the altitude region of 88-100 km, the initiation of the gradient drift waves is observed at altitudes of 91 and 93 km during 40% and 72% obscuration levels respectively on a solar eclipse day. However, on a control day, in the presence of average electron density scale length of 9 km, these waves are found at altitude as low as 88 km. In addition, the amplitude of the gradient drift waves is found to be the largest during the 72% obscuration level compared to those during the 40% obscuration level and control day. In the absence of electric field measurements, the magnetometer observations are used to infer an increase in the polarization electric field when the obscuration level is around 72%. This along with steeper gradient can account for the increase in the amplitude of gradient drift waves during 72% obscuration compared to 40% obscuration. The relative role of the growth and decay of the gradient drift waves is discussed in the context of these observations.

  18. Observations of plasma wave turbulence generated around large ionospheric spacecraft: Effects of motionally induced EMF and of electron beam emission

    SciTech Connect

    Neubert, T.; Gilchrist, B.E.; Banks, P.M. ); Sasaki, S. ); Fraser-Smith, A.C. ); Raitt, W.J. )

    1991-06-01

    The authors report on observations of plasma wave turbulence generated during electron beam injections, spacecraft potential variations, and neutral gas emissions of the CHARGE 2 sounding rocket experiment. The payload was flown in a mother/daughter configuration, with the two sub-payloads electrically connected by an insulated, conducting tether. While tethered, the two platforms were separated, drifting apart in a direction perpendicular to both the magnetic field and to the spacecraft velocity, reaching a maximum distance of 426 m at the end of the flight. The mother carried a high-voltage (HV) system (0-460 V), biasing the mother negative relative to the daughter. The operation of the HV bias system simulated the motional emf induced in larger orbiting space structures like the Tethered Satellite System 1 (TSS 1) space shuttle mission scheduled for the spring of 1992. In addition, the mother carried an electron beam accelerator (1 keV, 0-46 mA). The daughter diagnostics included wave receivers (400 Hz to 10 MHz) connected to a pair of electric dipole antennas. Broadband ELF/VLF turbulence was generated both during electron beam emissions and when the HV bias system was operated, while turbulence in the HF range was observed only during electron beam emissions. As a result of the electrical connection through the tether, the ELF/VLF wave intensities show little variation with separation distance of the two payloads. Two sources of wave turbulence are proposed to account for the observations: (1) wave turbulence generated by the beam/spacecraft system in particular in the HF range, and (2) electron return currents to the daughter simulating VLF noise during HV operations and electron beam emissions.

  19. The Super Dual Auroral Radar Network (SuperDARN): A ground-based array of HF radars for global-scale studies of ionospheric and magnetospheric processes

    NASA Astrophysics Data System (ADS)

    Greenwald, R. A.

    2004-05-01

    Radars have been utilized since early in the 20th century for remote investigations of Earth's upper atmosphere. Many of the terms used to describe the ionosphere in particular were derived from the characteristics of radar soundings. It is now appreciated that the ionosphere also provides a portal for viewing processes in the magnetosphere, including the impact of variability in the solar wind. Beginning in the 1970s, efforts were made to construct small systems of ionospheric radars for research at high latitudes (e.g., STARE, SABRE). These efforts culminated in the last decade with the realization of the SuperDARN concept. An international consortium of researchers and funding agencies assembled networks of HF radars that provide large-scale coverage of the high-latitude ionosphere in both hemispheres. The northern component comprises 9 instruments with sites that extend westward from Scandinavia to Alaska while the southern component consists of 6 instruments with fields of view that converge over Antarctica. The radars observe coherent backscatter from ionization irregularities in the E and F regions and measure their motions. Synthesis of the velocity data sets results in global-scale images of the convection of ionospheric plasma that are analogous to images of auroral luminosity obtained with spaced-based instruments. The radars operate continuously with a cadence of 1 or 2 minutes. Summary information is downloaded from the northern radars via real-time internet links to JHU/APL where they are combined into a nowcast of the ionospheric space weather. Further expansion of SuperDARN is planned for both hemispheres and may include sites that will extend the coverage higher into the polar cap and to mid-latitudes. The range of studies pursued with SuperDARN includes convection dynamics, M-I coupling, atmospheric gravity waves, substorm processes, ionospheric modeling, and ULF pulsations. New areas for development include estimation of the global Poynting flux with the Iridium satellite network, coordinated studies of the polar cap ionosphere with AMISR, and the exploitation of meteor scatter to study the global distribution of mesospheric winds. In this talk we will review the status of SuperDARN, describe some of the scientific and technical accomplishments to date, and discuss the application of the data to the solution of current research problems.

  20. Radar studies of high latitude convection flows

    NASA Astrophysics Data System (ADS)

    Burrage, Mark David

    1988-06-01

    Studies of the electrodynamics of the high latitude ionosphere contribute to the understanding of the coupling between the solar wind, magnetosphere and upper atmosphere. This thesis describes an experimental investigation of high latitude E-region convection flows carried out with the Sweden And Britain auroral Radar Experiment (SABRE). The ionospheric observations have been related to satellite measurements of the interplanetary medium and hence interpreted in terms of models of solar wind-magnetosphere-ionosphere coupling processes. A close relationship has been established between various solar wind parameters and the daily mean SABRE backscatter intensity, a quantity which is rarely employed in geophysical studies. Empirical IMF-dependent models of the convection flows observed by SABRE are developed and statistical studies of the occurrence time of the Harang discontinuity are presented. High spatial resolution, two dimensional maps of the ionospheric projection of the dayside merging region, for both polarities of the azimuthal component of the IMF, are obtained for the first time. Two examples of strong nightside convection flows observed throughout the SABRE latitude range indicate that the convection flows may penetrate at least as far south as 61.5 degrees N, geomagnetic latitude, during strongly northward IMF. The study indicates that, in the long term, the structure of the solar wind can be deduced from the mean backscatter intensity measured by a SABRE radar. In addition, the azimuthal component of the IMF exerts a crucial influence on the convection flows observed by SABRE in the cusp region. This effect is not confined to the noon sector but is also apparent in the vicinity of the Harang discontinuity. In general, the convection pattern exhibits a dependence on the north-south component of the IMF consistent with established reconnection mechanisms. However, there is evidence that existing models are insufficient to explain the anomalous convection flows observed under conditions of strongly northward IMF.

  1. Radar Studies of High Latitude Convection Flows

    NASA Astrophysics Data System (ADS)

    Burrage, Mark David

    Available from UMI in association with The British Library. Requires signed TDF. Studies of the electrodynamics of the high latitude ionosphere contribute to the understanding of the coupling between the solar wind, magnetosphere and upper atmosphere. This thesis describes an experimental investigation of high latitude E-region convection flows carried out with the Sweden And Britain auroral Radar Experiment (SABRE). The ionospheric observations have been related to satellite measurements of the interplanetary medium and hence interpreted in terms of models of solar wind-magnetosphere-ionosphere coupling processes. A close relationship has been established between various solar wind parameters and the daily mean SABRE backscatter intensity, a quantity which is rarely employed in geophysical studies. Empirical IMF-dependent models of the convection flows observed by SABRE are developed and statistical studies of the occurrence time of the Harang discontinuity are presented. High spatial resolution, two dimensional maps of the ionospheric projection of the dayside merging region, for both polarities of the azimuthal component of the IMF, are obtained for the first time. Two examples of strong nightside convection flows observed throughout the SABRE latitude range indicate that the convection flows may penetrate at least as far south as 61.5 ^circ N, geomagnetic latitude, during strongly northward IMF. The study indicates that, in the long term, the structure of the solar wind can be deduced from the mean backscatter intensity measured by a SABRE radar. In addition, the azimuthal component of the IMF exerts a crucial influence on the convection flows observed by SABRE in the cusp region. This effect is not confined to the noon sector but is also apparent in the vicinity of the Harang discontinuity. In general, the convection pattern exhibits a dependence on the north -south component of the IMF consistent with established reconnection mechanisms. However, there is evidence that existing models are insufficient to explain the anomalous convection flows observed under conditions of strongly northward IMF.

  2. 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 be an ionospheric signature of the plasmapause and its motion. The total TEC increase of this shoulder is 80%. Part of this increase may be due to a "superfountain effect." The dayside ionospheric TEC above 430 km decreased to values 45% lower than quiet day values 7 to 9 hours after the beginning of the electric field event. The total equatorial ionospheric TEC decrease was 16%. This decrease occurred both at midlatitudes and at the equator. We presume that thermospheric winds and neutral composition changes produced by the storm-time Joule heating, disturbance dynamo electric fields, and electric fields at auroral and subauroral latitudes are responsible for these decreases.

  3. Magnetospheric disturbances associated with the 13 December 2006 solar flare and their ionospheric effects over North-East Asia

    NASA Astrophysics Data System (ADS)

    Zolotukhina, N.; Polekh, N.; Kurkin, V.; Pirog, O.; Samsonov, S.; Moiseyev, A.

    2012-03-01

    We present an observational study of magnetospheric and ionospheric disturbances during the December 2006 intense magnetic storm associated with the 4В/Х3.4 class solar flare. To perform the study we utilize the ground data from North-East Asian ionospheric and magnetic observatories (60-72°N, 88-152°E) and in situ measurements from LANL, GOES, Geotail and ACE satellites. The comparative analysis of ionospheric, magnetospheric and heliospheric disturbances shows that the interaction of the magnetosphere with heavily compressed solar wind and interplanetary magnetic field caused the initial phase of the magnetic storm. It was accompanied by the intense sporadic E and F2 layers and the total black-out in the nocturnal subauroral ionosphere. During the storm main phase, LANL-97A, LANL 1994_084, LANL 1989-046 and GOES_11 satellites registered a compression of the dayside magnetosphere up to their orbits. In the morning-noon sector the compression was accompanied by an absence of reflections from ionosphere over subauroral ionospheric station Zhigansk (66.8°N, 123.3°E), and a drastic decrease in the F2 layer critical frequency (foF2) up to 54% of the quite one over subauroral Yakutsk station (62°N, 129.7°E). At the end of the main phase, these stations registered a sharp foF2 increase in the afternoon sector. At Yakutsk the peak foF2 was 1.9 time higher than the undisturbed one. The mentioned ionospheric disturbances occurred simultaneously with changes in the temperature, density and temperature anisotropy of particles at geosynchronous orbit, registered by the LANL-97A satellite nearby the meridian of ionospheric and magnetic measurements. The whole complex of disturbances may be caused by radial displacement of the main magnetospheric domains (magnetopause, cusp/cleft, plasma sheet) with respect to the observation points, caused by changes in the solar wind dynamic pressure, the field of magnetospheric convection, and rotation of the Earth.

  4. Plasma irregularities in the duskside subauroral ionosphere as observed with midlatitude SuperDARN radar in Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Hosokawa, K.; Nishitani, N.

    2010-08-01

    We revealed the spatial distribution of HF radar echoes in the subauroral region by conducting a statistical analysis of scattering occurrence from the midlatitude Super Dual Auroral Radar Network (SuperDARN) radar in Hokkaido, Japan. Consequently, Dusk Scatter Event (DUSE) was identified as a most prominent backscatter target in these latitudes. Past studies have intended to associate an appearance of DUSE with the density gradient at the poleward or sunward edges of the midlatitude trough. However, exact spatial collocation between the source region of DUSE and the midlatitude trough has not been revealed because the SuperDARN radars in the auroral region could not observe the whole part of DUSE due to a limitation of the field-of-view coverage. Thus, it has been unclear which of the density gradients associated with the midlatitude trough is responsible for generating DUSE. The data from the Hokkaido radar enabled us to estimate the lower-latitude boundary of DUSE as around 59 in AACGM magnetic latitude. In addition, by adding the data from the King Salmon radar in Alaska we derived a complete statistical distribution of DUSE. The latitudinal extent of DUSE is about 9 from 59 to 68, which is approximately 1000 km. The statistical distribution of DUSE was compared with the model of the midlatitude trough. As a result, the source region of DUSE is closely colocated with the minimum of the trough, which suggests that the electron density gradient at the sunward edge of the trough is responsible for DUSE. This means that the location of the duskside sunward edge (i.e., local time extent) of the midlatitude trough can be monitored by using an appearance of DUSE as a proxy. The current statistical analysis also suggests that we can derive a spatial distribution of HF radar echoes from the midlatitudes to high latitudes by combining the data from the Hokkaido and King Salmon radars located in the Far Eastern area, which would be a very powerful diagnostic tool for investigating the global distribution of plasma irregularities.

  5. Radio wave heating of the lower ionosphere

    SciTech Connect

    Freeman, M.J.

    1993-01-01

    The interaction of high power, high frequency radio waves with the lower ionosphere is becoming an area of considerable theoretical and experimental interest. In particular, significant ohmic heating of the collisional, weakly ionized ionospheric plasma is possible, which can change the absorptive and conductive properties of the plasma in a nonlinear fashion. Precisely controlled heating may have applications to the production of ELF/VLF waves in the ionosphere by the stimulation when inferring the physical parameters of the sources. The necessary generalizations to the standard synchrotron self-Compton theory are presented. Relativistic induced Compton scattering is very sensitive to the number of mildly relativistic electrons in the source, and so may be a useful probe to this portion of the electron energy distribution.

  6. Ionospheric response to the sustained high geomagnetic activity during the March '89 great storm

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    A simulation was conducted to model the high-latitude ionospheric to the sustaied level of high geomagnetic activity for the great magnetic storm period of March 13-14, 1989. The geomagnetic and solar activity indices and the Defense Meterological Satellite Program (DMSP) F8 and F9 satellite data for particle precipitation and high-latitude convection were used as inputs to a time-dependent ionospheric model (TDIM). The results of the TDIM were compared to both DMSP plasma density data and ground-based total electron content (TEC) measurements for the great storm period as well as with earlier storm observations. The comparisons show that the overall structure of the high-latitude ionosphere was dominated by an increased convection speed within the polar cap that led to increased ion temperatures. In turn, this enhanced the NO(+) density, raised the atomic-to-molecular ion transition height to over 300 km, decreased N(sub m)F(sub 2), increased h(sub m)F(sub 2), and in places either increased n(sub e) at 800 km or slightly decreased it. The morphology of the ionosphere under these extreme conditions was considerably different than that modeled for less distributed intervals. These differences included the character of the dayside tongue of ionization that no longer extended deep into the polar cap. Instead, as a result of the ion heating and consequent reduction in N(sub m)F(sub 2), a large polar hole occupied much of the polar region. This polar hole extended beyond the auroral oval and merged with the night sector midatitude trough. The limitaions associated with the applicability of the TDIM to the geomagnetic conditions present on March 13 and 14 are discussed. The primary limitations of the TDIM derive from the limited temporal resolution of the model input parameters and the lack of suitably dynamic thermospheric specification for the great storm conditions. These limitations leads to midlatitude ionospheric storm phases that do no follow those observed.

  7. 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.

  8. A new interhemispheric 16-moment model of the plasmasphere-ionosphere system: IPIM

    NASA Astrophysics Data System (ADS)

    Marchaudon, A.; Blelly, P.-L.

    2015-07-01

    We present a new interhemispheric numerical model: the IRAP plasmasphere-ionosphere model (IPIM). This model describes the transport of the multispecies ionospheric plasma from one hemisphere to the other along convecting and corotating magnetic field lines, taking into account source processes at low altitude such as photoproduction, chemistry, and energization through the coupling with a kinetic code solving the transport of suprathermal electron along the field line. Among the new developments, a 16-moment-based approach is used for the transport equations in order to allow development of strong temperature anisotropy at high altitude and we consider important but often neglected effects, such as inertial acceleration (centrifugal and Coriolis). In this paper, after presenting in detail the principle of the model, we focus on preliminary results showing the original contribution of this new model. For these first runs, we simulate the convection and corotation transport of closed flux tubes in the plasmasphere for tilted/eccentric dipolar magnetic field configuration in solstice and equinox conditions. We follow different flux tubes between 1.2 and 6 Earth Radii (RE) and demonstrate the capability of the model to describe a wide range of density (above 15 orders of magnitude). The relevance of the mathematical approach used is highlighted, as anisotropies can develop above 3000 km in the plasmasphere as a result of the mirroring effect related to the anisotropic pressure tensor. Moreover, we show that the addition of inertial acceleration may become critical to describe plasma interhemispheric transport above 4RE. The ability of the model to describe the external plasmasphere is demonstrated, and innovative studies are foreseen, regarding the dynamics of the plasma along the magnetic field lines (in particular interhemispheric exchanges and "opening"/"closure" of a flux tube).

  9. Convection in Neptune's magnetosphere

    NASA Technical Reports Server (NTRS)

    Hill, T. W.; Dessler, A. J.

    1990-01-01

    It is assumed that nonthermal escape from Triton's atmosphere produces a co-orbiting torus of unionized gas (presumably nitrogen and hydrogen) that subsequently becomes ionized by electron impact to populate a partial Triton plasma torus analogous to the Io plasma torus in Jupiter's magnetosphere. Centrifugal and magnetic-mirror forces confine the ions to a plasma sheet located between the magnetic and centrifugal equators. The ionization rate, and hence the torus ion concentration, is strongly peaked at the two points (approximately 180 deg apart in longitude) at which Triton's orbit intersects the plasma equator. During the course of Neptune's rotation these intersection points trace out two arcs roughly 75 deg in longitudinal extent, which we take to be the configuration of the resulting (partial) plasma torus. The implied partial ring currents produce a quadrupolar (four-cell) convection system that provides rapid outward transport of plasma from the arcs. Ring-current shielding, however, prevents this convection system from penetrating very far inside the plasma-arc distance. It is suggested that this convection/shielding process accounts for the radial confinement of trapped particles (150 keV or greater) within L = 14.3 as observed by the Voyager LECP instrument.

  10. Ionospheric holes - A review of theory and recent experiments

    NASA Technical Reports Server (NTRS)

    Mendillo, Michael

    1988-01-01

    Artificially induced ionospheric holes result from in situ injections of highly reactive molecules, which greatly enhance the chemical recombination rates between the ions and electrons found in the upper atmosphere. During the past decade, experiment-of-opportunity observations, theory and computer simulations have succeeded in establishing plasma-depletion experiments as a useful tool for probing the normal and disturbed behavior of the ionosphere. Ionospheric-hole experiments now focus on applications of the technique to laboratory-in-space investigations of various space plasma processes.

  11. 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.

  12. Seasonal differences in ionospheric current rise and decay times

    NASA Astrophysics Data System (ADS)

    Laundal, K.; Ostgaard, N.; Reistad, J. P.; Tenfjord, P.; Snekvik, K.

    2014-12-01

    We investigate how different seasonal conditions are associated with differences in the ionospheric response to the same magnetospheric and solar wind drivers. In particular, we use ground magnetometer data, made available by SuperMAG, to derive equivalent current maps, and analyze how these currents respond to 1) Substorm onsets, and 2) rapid changes in the interplanetary magnetic field (IMF). We find that at substorm onset, determined from global auroral imaging, the average ionospheric current starts to increase almost immediately in the winter hemisphere, while a several minutes delay is observed in the summer hemisphere. In the winter hemisphere, the increase in current is on average larger than in the summer hemisphere during the substorm growth phase. During substorm recovery, the current decays more rapidly in the winter hemisphere, compared to the summer hemisphere. This is consistent with some earlier studies that show that the ionospheric convection changes more slowly when the ionospheric conductance is high.

  13. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    NASA Astrophysics Data System (ADS)

    Lay, Erin H.; Shao, Xuan-Min; Kendrick, Alexander K.; Carrano, Charles S.

    2015-07-01

    Acoustic waves with periods of 2-4 min and gravity waves with periods of 6-16 min have been detected at ionospheric heights (250-350 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.

  14. Ionospheric acoustic and gravity waves associated with midlatitude thunderstorms

    DOE PAGESBeta

    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

  15. 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.

  16. 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.

  17. Dynamic Ionosphere Cubesat Experiment (DICE)

    NASA Astrophysics Data System (ADS)

    Crowley, G.; Fish, C. S.; Bust, G. S.; Swenson, C.; Barjatya, A.; Larsen, M. F.

    2009-12-01

    The Dynamic Ionosphere Cubesat Experiment (DICE) mission has been selected for flight under the NSF "CubeSat-based Science Mission for Space Weather and Atmospheric Research" program. The mission has three scientific objectives: (1) Investigate the physical processes responsible for formation of the midlatitude ionospheric Storm Enhanced Density (SED) bulge in the noon to post-noon sector during magnetic storms; (2) Investigate the physical processes responsible for the formation of the SED plume at the base of the SED bulge and the transport of the high density SED plume across the magnetic pole; (3) Investigate the relationship between penetration electric fields and the formation and evolution of SED. The mission consists of two identical Cubesats launched simultaneously. Each satellite carries a fixed-bias DC Langmuir Probe (DCP) to measure in-situ ionospheric plasma densities, and an Electric Field Probe (EFP) to measure DC and AC electric fields. These measurements will permit accurate identification of storm-time features such as the SED bulge and plume, together with simultaneous co-located electric field measurements which have previously been missing. The mission team combines expertise from ASTRA, Utah State University/Space Dynamics Laboratory (USU/SDL), Embry-Riddle Aeronautical University and Clemson University.

  18. The Importance of Microphysical Processes in the Magnetosphere-Ionosphere System

    NASA Astrophysics Data System (ADS)

    Lotko, W.

    2012-12-01

    The effects of low-altitude collisionless energy conversion on global aspects of the magnetosphere-ionosphere (M-I) interaction are considered. Electromagnetic power flowing from the magnetosphere into auroral and cusp regions is converted, via an abundance of collisionless plasma processes, to beams of precipitating electrons and transversely accelerated ions (TAIs), principally O+ due to its larger gyroradius. Electron precipitation gates ionospheric Joule dissipation by modifying the ionospheric conductance. Depending on its energy spectrum and flux, precipitation also increases the scale height of the ionosphere, thereby enhancing the source population of TAIs. TAIs become ionospheric outflows under the action of the mirror force. Outflows have the capacity to inflate and stretch the nightside plasmasheet and modify the nightside reconnection rate. Their effects seem to be integral in determining (in global simulations) whether the M-I system, for steady solar wind (SW) driving, settles into a steady magnetospheric convection mode or a sawtooth mode. By enhancing the asymmetric ring current, outflows also effectively change the shape of the magnetospheric boundary, which changes the solar wind - magnetosphere interaction, the dayside reconnection potential, the cross polar cap potential, ionospheric Joule dissipation and the current-voltage characteristics of the SW-M-I interaction. From a dynamical system perspective, one is tempted to trace the causal chain from solar wind and magnetotail dynamos, to the resulting electromagnetic power flows that deposit energy at low altitude, to conversion of this energy to particle beams and heat, and, then, to ascribe observed morphologies of these processes to the distributions of the dynamos. However, it will be shown using global simulation experiments that the morphology and dynamics and, to some extent, the power derived from the dynamos is determined as much by the M-I interaction as by the SW-M interaction. This behavior is indicative of a geospace system exhibiting strong coupling and feedback among its internal elements. That the products of energy conversion (electron beams and ion flows) enabled by local, microphysical processes feedback into global system behavior is also indicative of a scale-interactive system: Large-scale processes regulate microprocesses, which, in turn, regulate the large-scale processes.

  19. Asymmetry of the Venus nightside ionosphere: Magnus force effects

    NASA Astrophysics Data System (ADS)

    Prez-de-Tejada, H.

    2008-11-01

    A study of the dawn-dusk asymmetry of the Venus nightside ionosphere is conducted by examining the configuration of the ionospheric trans-terminator flow around Venus and also the dawn-ward displacement of the region where most of the ionospheric holes and the electron density plateau profiles are observed (dawn meaning the west in the retrograde rotation of Venus and that corresponds to the trailing side in its orbital motion). The study describes the position of the holes and the density plateau profiles which occur at neighboring locations in a region that is scanned as the trajectory of the Pioneer Venus Orbiter (PVO) sweeps through the nightside hemisphere with increasing orbit number. The holes are interpreted as crossings through plasma channels that extend downstream from the magnetic polar regions of the Venus ionosphere and the plateau profiles represent cases in which the electron density maintains nearly constant values in the upper ionosphere along the PVO trajectory. From a collection of PVO passes in which these profiles were observed it is found that they appear at neighboring positions of the ionospheric holes in a local solar time (LST) map including cases where only a density plateau profile or an ionospheric hole was detected. It is argued that the ionospheric holes and the density plateau profiles have a common origin at the magnetic polar regions where plasma channels are formed and that the density plateau profiles represent crossings through a friction layer that is adjacent to the plasma channels. It is further suggested that the dawn-dusk asymmetry in the position of both features in the nightside ionosphere results from a fluid dynamic force (Magnus force) that is produced by the combined effects of the trans-terminator flow and the rotational motion of the ionosphere that have been inferred from the PVO measurements.

  20. Polar cap convection: Steady state and dynamic effects

    NASA Astrophysics Data System (ADS)

    Moses, Julie J.; Reiff, Patricia H.

    Over the past few years, a good deal of work has been expended in qualitatively and quantitatively determining the patterns of steady state polar cap convection and their dependence on interplanetary conditions. A consensus is emerging as to the general characteristics of the patterns, at least during southward Interplanetary Magnetic Field (IMF) conditions. During times of northward IMF, however, there is still a substantial controversy as to how many distinct convection cells exist. Regions of sunward flow well poleward of the apparent location of the last closed field line are frequently observed during northward IMF (and at least sometimes during southward IMF). These regions are variously explained as either part of a separate convection cell completely confined to the polar cap, or as just a sunward meander in an otherwise "normal" two-cell convection pattern. Time variations (including the passage of a traveling convection vortex) may explain some of those events, but apparently not all of them. Quantitative parameterizations of polar cap convection are progressing rapidly. The first such work merely related the magnitude of the cross-polar cap electrostatic potential drop versus interplanetary parameters, and this kind of study continues. Recent developments include correlating the dawnside plasmasheet potential drop with AU and the duskside with AU; and examining effects of substorm phase on the potential. In addition, attempting to develop a model which takes into account the time history of the IMF is critical. Empirical models to determine the convection pattern by making statistical averages of flow components at a given place under given IMF conditions generally yield patterns which are considerably less structured than what is typically observed. This kind of approach is severely hampered by the fact that polar cap boundary motion means that invariably sunward and antisunward flow components are averaged together, yielding a mean flow speed which is considerably smaller than the median speed. Another complementary approach is that of the "pattern recognition" type, where one uses one's experience in observing hundreds of polar cap crossings to create a typical pattern, and then creating an analytical representation of that pattern using adjustable parameters. The goal of that approach is to find a simple dependence of those parameters on interplanetary conditions. Finally, a critical issue is substorm effects on the nightside convection pattern. The EISCAT POLAR experiment has yielded very exciting results on the local two-dimensional convection pattern and its dependence on, for example, westward traveling surges. A key topic to address in the next few years is how that convection pattern maps out to the nightside plasma sheet. This is by no means easy to answer, since the existence of parallel electric fields make mapping of ionospheric electric fields out to the magnetotail quite tricky, especially since the magnetic field structure during those times is quite dynamic. This question has serious consequences, however, in the fraction of the plasma sheet plasma which becomes injected into the inner magnetosphere. Thus the topic of polar cap convection is far from being a stagnant field, and much interesting work is still in store to solve these fascinating controversies.

  1. 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

  2. Effect of an MLT dependent electron loss rate on the magnetosphere-ionosphere coupling

    NASA Astrophysics Data System (ADS)

    Gkioulidou, Matina; Wang, Chih-Ping; Wing, Simon; Lyons, Larry R.; Wolf, Richard A.; Hsu, Tung-Shin

    2012-11-01

    As plasma sheet electrons drift earthward, they get scattered into the loss cone due to wave-particle interactions and the resulting precipitation produces auroral conductance. Realistic electron loss is thus important for modeling the magnetosphere - ionosphere (M-I) coupling and the degree of plasma sheet electron penetration into the inner magnetosphere. In order to evaluate the significance of electron loss, we used the Rice Convection Model (RCM) coupled with a force-balanced magnetic field to simulate plasma sheet transport under different electron loss rates and under self-consistent electric and magnetic field. We used different magnitudes of i) strong pitch angle diffusion everywhere electron loss rate (strong rate) and ii) a more realistic loss rate with its MLT dependence determined by wave activity (MLT rate). We found that electron pressure under the MLT rate is larger compared to the strong rate inside L ∼ 12 RE. The dawn-dusk asymmetry in the precipitating electron energy flux under the MLT rate, with much higher energy flux at dawn than at dusk, agrees better with statistical DMSP observations. High-energy electrons inside L ∼ 8 RE can remain there for many hours under the MLT rate, while those under the strong rate get lost within minutes. Under the MLT rate, the remaining electrons cause higher conductance at lower latitudes; thus after a convection enhancement, the shielding of the convection electric field is less efficient, and as a result, the ion plasma sheet penetrates further earthward into the inner magnetosphere than under the strong rate.

  3. 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.

  4. 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).

  5. MAGNUS FORCE EFFECTS IN THE ROTATING IONOSPHERES OF VENUS AND MARS

    NASA Astrophysics Data System (ADS)

    Perez de Tejada, H. A.; Lundin, R.

    2009-12-01

    Measurements conducted with the ORPA instrument of the Pioneer Venus Orbiter in the Venus ionosphere and with the ASPERA-3 instrument of the Mars Express spacecraft in the Mars ionosphere have been examined to identify effects related to the Magnus force that is produced by the combined presence of the directed motion of each planet's eroded upper ionospheric plasma and the rotating lower altitude region of their ionosphere. The overall response of the ionosphere to that force is a dawn-dusk asymmetry in the distribution of the upper nightside ionosphere as well as in the plasma wake that extends downstream from it. At Venus the high altitude ionospheric trans-terminator flow is displaced towards the dawn side consistent with the fast retrograde rotation of that planet's atmosphere. At Mars the velocity vectors derived from the ASPERA-3 measurements in that planet's ionosphere are examined to determine if there is a dawnward deflection in the distribution of the eroded ionospheric plasma consistent with the prograde rotational motion of the planet and its atmosphere. Calculations are carried out to estimate the angular deflection of the upper layers of the ionospheric plasma that is eroded by the solar wind in each planet.

  6. 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.

  7. Saturn ionosphere - Theoretical interpretation

    NASA Astrophysics Data System (ADS)

    Atreya, S. K.; Waite, J. H.

    1981-08-01

    Voyager 1 high latitude and Pioneer 11 equatorial ionospheric structure indicate a solar EUV-controlled ionosphere with a possible molecular ion in the topside. Vibrationally excited H2 in the high latitudes may be an important loss mechanism. Dynamical effects are expected to be important for determining the peak density and its location.

  8. 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.

  9. 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.

  10. Modeling ionospheric absorption modified by anomalous heating during substorms

    NASA Astrophysics Data System (ADS)

    Milikh, G. M.; Dimant, Y. S.; Shao, X.; Guzdar, P. N.; Sharma, A. S.; Papadopoulos, K.; Burns, E. M.; Goodrich, C. C.; Rosenberg, T. J.; Weatherwax, A. T.; Wiltberger, M. J.; Lyon, J. G.; Fedder, J. A.

    Riometers monitor the changes in ionospheric conductivity by measuring the absorption of very high frequency radio noise of galactic origin passing through the ionosphere. In this Letter the absorption of radio signals by a thin layer of ionospheric plasma, produced by ionization due to energetic precipitating electrons, is modeled by taking into account strong turbulent heating caused by instabilities. The precipitating electron population is obtained from a global MHD simulation of the magnetosphere, along with the electric fields which excite the Farley-Buneman instability and lead to turbulent electron heating. A comparison, the first of its kind, of the data from polar and sub-auroral riometers for the magnetic cloud event of January 10, 1997 shows good agreement. The ionospheric conductance modified by turbulent electron heating can be used to improve the magnetosphere — ionosphere coupling in the current global MHD models.

  11. Ionospheric parameters estimation using GLONASS/GPS data

    NASA Astrophysics Data System (ADS)

    Sidorenko, K. A.; Vasenina, A. A.

    2016-05-01

    In recent time, GLONASS/GPS signals are widely used for continuous monitoring of the ionospheric plasma conditions. However the ground-based GLONASS/GPS station for sounding of the ionosphere cannot provide high spatial resolution. To solve this problem, ionospheric models are used. In this article the algorithm of ionospheric model adaptation according to GLONASS/GPS data is offered. The expediency of use as the adaptive parameter values of the solar 10.7 cm radio flux index, which characterizes the level of solar activity, is shown. The adaptation parameter is defined by the minimization of the difference between the correlation matrices of the experimental and modeled TEC values. Reducing errors in the determination of ionospheric parameters in comparison with the simulation results is confirmed by experimental works in Moscow.

  12. Semikinetic modeling and observations of high-latitude plasma outflow

    NASA Technical Reports Server (NTRS)

    Horwitz, James L.

    1995-01-01

    In one fo the most exciting areas of progress, we have now developed a dynamic semikinetic model for examining the synergistic effects of waves and magnetospheric hot plasma populations on the outflowing ionospheric plasma. We have done this by imposing hot biMaxwellian ion and electron distributions at the top of our auroral simulation flux tube (4 R(sub e)), as well as a spectrum of waves with altitude which perpendicularly heats the ionospheric ions. We have also addressed the quasi-statistical properties of out flowing O(+) through bulk parameter analysis of DE-1/RIMS observations when DE-1 was in the midaltitude polar cap magnetosphere. A very exciting paper which was both submitted and appeared during this period in JGR concerned the centrifugal acceleration effect on the polar wind. During this year, we also developed the extension of our GSK code to include the lower ionosphere and associated processes. Finally, perhaps our most exciting project currently is a study of F-region upflows using a modification of the FLIP ionospheric fluid dynamics model of Richards and Torr to allow for the effects of soft electron precipitation ionization and convection-driven ion heating, and performed comparisons with satellite and radar data. A list of reference papers that have been published is listed.

  13. Examples of meteorological behavior of the ionosphere

    NASA Astrophysics Data System (ADS)

    Bibl, K.

    1989-04-01

    For some time the network of ionosonde stations in Europe were dense enough to study the meteorological behavior of the ionosphere. Because the electron recombination near the maximum of the F-region ionization is sufficiently small, the maximum electron density and the profile are controlled substantially by dynamic processes. Gravity waves and vertical plasma drift and its vertical gradients change the F-layer ionization significantly. In fixed frequency ionosonde recordings the author has discovered direct oblique echoes from a hole in the ionosphere over the Alps. Maps were drawn to show the meteorological properties of this European Anomaly either as a time development of a cross-section of Europe from northern Germany to Rome, Italy using six stations, or as a sequence of a contour maps of the ionosphere over Europe using ten stations. A short animated movie was produced demonstrating the development of the hole in the ionosphere and its recovery with a curl developing. Even the average behavior of the F-region ionization shows substantial differences with location. In Europe the variations of the local gradients in ionization can be different by a factor of two over two locations separated by 1000 km. This behavior, important for understanding the meteorology of the ionosphere and for precise ionspheric radio predictions, certainly requires intense studies with digital sounders in Europe and at other locations.

  14. Characteristics of High Latitude Ionosphere Scintillations

    NASA Astrophysics Data System (ADS)

    Morton, Y.

    2012-12-01

    As we enter a new solar maximum period, global navigation satellite systems (GNSS) receivers, especially the ones operating in high latitude and equatorial regions, are facing an increasing threat from ionosphere scintillations. The increased solar activities, however, also offer a great opportunity to collect scintillation data to characterize scintillation signal parameters and ionosphere irregularities. While there are numerous GPS receivers deployed around the globe to monitor ionosphere scintillations, most of them are commercial receivers whose signal processing mechanisms are not designed to operate under ionosphere scintillation. As a result, they may distort scintillation signal parameters or lose lock of satellite signals under strong scintillations. Since 2008, we have established and continuously improved a unique GNSS receiver array at HAARP, Alaska. The array contains high ends commercial receivers and custom RF front ends which can be automatically triggered to collect high quality GPS and GLONASS satellite signals during controlled heating experiments and natural scintillation events. Custom designed receiver signal tracking algorithms aim to preserve true scintillation signatures are used to process the raw RF samples. Signal strength, carrier phase, and relative TEC measurements generated by the receiver array since its inception have been analyzed to characterize high latitude scintillation phenomena. Daily, seasonal, and solar events dependency of scintillation occurrence, spectral contents of scintillation activities, and plasma drifts derived from these measurements will be presented. These interesting results demonstrate the feasibility and effectiveness of our experimental data collection system in providing insightful details of ionosphere responses to active perturbations and natural disturbances.

  15. COSMIC-2: A Platform for Advanced Ionospheric Observations

    NASA Astrophysics Data System (ADS)

    Straus, P. R.; Betz, D. A.

    2013-12-01

    The equatorial component of the COSMIC-2 program will consist of 6 satellites to be flown in a 24 degree inclination/520 km altitude orbit. In addition to the primary GNSS radio occultation (RO) payload, to be provided by JPL, the USAF plans to fly a pair of space weather sensors: a multi-frequency radio beacon and the Velocity, Ion Density and Irregularities (VIDI) in-situ plasma sensor package. Together, these three instruments will provide data to address key issues related to the specification and forecast of ionospheric densities and the instabilities/irregularities associated with ionospheric scintillation. The TriG GNSS receiver will provide a substantial increase in the number of daily ionospheric observations relative to COSMIC-1, both in the RO limb-viewing and overhead geometries. These data will provide a significant improvement of assimilative model capabilities for providing accurate ionospheric specifications in the important equatorial region. In addition, TriG will make routine measurements of ionospheric scintillation at L-band frequencies, as pioneered by the CORISS instrument on C/NOFS. The radio beacon, together with a network of ground receivers, will enable direct measurement of scintillation effects on trans-ionospheric signal propagation across the UHF to S-band frequency spectrum. The VIDI sensors will measure the in-situ density depletions associated with scintillation-producing irregularities. Together, the beacon, TriG, and VIDI will provide an unprecedented ability to map equatorial ionospheric instabilities and their effects. The in-situ package will also provide observations of plasma drifts from which electric fields, the most important physical driver for equatorial ionospheric structure, can be inferred. This will enable advancements in ionospheric models to further improve specifications and forecasts. In addition to discussing ionospheric science and operational support aspects of the COSMIC-2 mission, this presentation will also discuss high level COSMIC-2 programmatic status and plans, particular with respect to the mission sensors.

  16. 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.

  17. 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.

  18. Plasmasphere-ionosphere coupling. 2. Ion composition measurements at plasmaspheric and ionospheric altitudes and comparison with modeling results

    SciTech Connect

    Horwitz, J.L.; Comfort, R.H.; Richards, P.G. ); Chandler, M.O.; Chappell, C.R. ); Anderson, P.; Hanson, W.B. ); Brace, L.H. )

    1990-06-01

    Observations of plasmasphere-ionosphere coupling are made through thermal plasma measurements by the dual-spacecraft mission Dynamics Explorer. DE 1 measurements of ion composition and temperatures at 1.4-3.5 R{sub E} in the plasmasphere are combined with DE 2 measurements of the ion composition and electron and ion temperatures in the upper F region topside ionosphere closely spaced in universal and local time for cases in the period November 6-11, 1981. The findings include the following: (1) In some cases, there is evidence that the light ion latitudinal density profiles in the upper ionosphere resemble those for the plasmasphere even though the dominant O{sup +} density profile in the ionosphere is typically much smoother and flatter. (2) There is strong evidence that the O{sup +} density profile variations within the plasmasphere correlate with the ion and electron temperature latitudinal variations in both the plasmasphere and ionosphere, but have very little correlation with the comparatively smooth ionospheric O{sup +} density profile. (3) The He{sup +}/H{sup +} density ratio is typically much greater than unity in the upper ionosphere sampled by DE 2, but is around 0.2 in the plasmasphere data taken by greater than unity in the upper ionosphere sampled by DE 2, but is around 0.2 in the plasmasphere data taken by DE 1. (4) The latitudinal variations of ionospheric O{sup +} temperature and plasmaspheric H{sup +} temperature are broadly similar in that both show general increases with latitude and occasional correlated peaks in the outer plasmasphere, although the plasmaspheric temperatures are typically a factor of 3 or more larger than the ionospheric temperatures. The observations are compared directly with calculations of altitudinal ion density and temperature profiles from the field-line interhemispheric plasma (FLIP) model.

  19. 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.

  20. Seasonal and geomagnetic response of the thermosphere and ionosphere.

    NASA Astrophysics Data System (ADS)

    Rees, D.; Fuller-Rowell, T. J.

    1989-04-01

    The numerical and computational merging of the University College London Global Thermospheric Model and the Sheffield University Ionospheric Model has produced a self-consistent coupled thermospheric - ionospheric model, a valuable diagnostic tool for examining thermospheric - ionospheric interactions. The neutral thermospheric wind velocity, composition, density, and energy budget are computed, including their full interactions with the high-latitude ion drift and the evolution of the plasma density. A series of simulations has been performed at high solar activity, for a level of moderate geomagnetic activity, for each of the June and December solstices, and positive and negative values of the IMF-BY component.

  1. Evidence of Medium Scale (~50 km) Undulations Observed at Sunset in the Equatorial Ionosphere by Electric Field and Plasma Density Probes on the C/NOFS Satellite Below the F-Peak in Conjunction with Larger Scale (~500 km) Depletions

    NASA Astrophysics Data System (ADS)

    Pfaff, R. F., Jr.; Freudenreich, H. T.; Klenzing, J.; Liebrecht, M. C.

    2014-12-01

    Electric field and plasma density observations gathered on the C/NOFS satellite are presented in cases where the ionosphere F-peak has been elevated above the satellite perigee of 400 km near sunset. During these passes, data from the electric field and plasma density probes on the satellite frequently show evidence of "medium scale" (40-80 km) undulations in conjunction with, yet distinct from, series of periodic, larger scale (200-800 km) density depletions. The observations suggest that a second category of wavelike variations of the bottomside plasma density may be important for the subsequent development of the larger scale density depletions and their associated "spread-F" irregularities. The electric fields associated with the medium scale undulations are typically a few mV/m with density variations of a few percent in which upwards E x B drifts are associated with their depletions. The undulations are observed both before and after local sunset and are typically observed, in the satellite frame as it journeys from west to east, prior to the onset of the larger scale depletions. We present examples of these medium scale undulations and discuss their implications for driving the larger scale depletions, possibly in a manner similar to that discussed by Hysell and Kudeki [2004], Kudeki et al. [2007], and others.

  2. Probability Density Functions of the Solar Wind Driver of the Magnetopshere-Ionosphere System

    NASA Astrophysics Data System (ADS)

    Horton, W.; Mays, M. L.

    2007-12-01

    The solar-wind driven magnetosphere-ionosphere system is a complex dynamical system in that it exhibits (1) sensitivity to initial conditions; (2) multiple space-time scales; (3) bifurcation sequences with hysteresis in transitions between attractors; and (4) noncompositionality. This system is modeled by WINDMI--a network of eight coupled ordinary differential equations which describe the transfer of power from the solar wind through the geomagnetic tail, the ionosphere, and ring current in the system. The model captures both storm activity from the plasma ring current energy, which yields a model Dst index result, and substorm activity from the region 1 field aligned current, yielding model AL and AU results. The input to the model is the solar wind driving voltage calculated from ACE solar wind parameter data, which has a regular coherent component and broad-band turbulent component. Cross correlation functions of the input-output data time series are computed and the conditional probability density function for the occurrence of substorms given earlier IMF conditions are derived. The model shows a high probability of substorms for solar activity that contains a coherent, rotating IMF with magnetic cloud features. For a theoretical model of the imprint of solar convection on the solar wind we have used the Lorenz attractor (Horton et al., PoP, 1999, doi:10.10631.873683) as a solar wind driver. The work is supported by NSF grant ATM-0638480.

  3. Height-dependent ionospheric variations in the vicinity of nightside poleward expanding aurora after substorm onset

    NASA Astrophysics Data System (ADS)

    Oyama, S.; Miyoshi, Y.; Shiokawa, K.; Kurihara, J.; Tsuda, T. T.; Watkins, B. J.

    2014-05-01

    High-latitude ionospheric variations at times near auroral substorms exhibit large temporal variations in both vertical and horizontal extents. Statistical analysis was made of data from the European Incoherent Scatter UHF radar at Tromsø, Norway, and International Monitor for Auroral Geomagnetic Effects magnetometer for finding common features in electron density, ion and electron temperatures and relating these to currents and associated heating. This paper particularly focused on the height dependencies. Results show clear evidences of large electric field with corresponding frictional heating and Pedersen currents located just outside the front of the poleward expanding aurora, which typically appeared at the eastside of westward traveling surge. At the beginning of the substorm recovery phase, the ionospheric density had a large peak in the E region and a smaller peak in the F region. This structure was named as C form in this paper based on its shape in the altitude-time plot. The lower altitude density maximum is associated with hard auroral electron precipitation probably during pulsating aurora. We attribute the upper F region density maximum to local ionization by lower energy particle precipitation and/or long-lived plasma that is convected horizontally into the overhead measurement volume from the dayside hemisphere.

  4. Multisensor profiling of a concentric gravity wave event propagating from the troposphere to the ionosphere

    NASA Astrophysics Data System (ADS)

    Azeem, Irfan; Yue, Jia; Hoffmann, Lars; Miller, Steven D.; Straka, William C.; Crowley, Geoff

    2015-10-01

    In this paper, we present near-simultaneous observations of a gravity wave (GW) event in the stratosphere, mesosphere, and ionosphere over the South Central United States and track it from its convective source region in the troposphere to the ionosphere, where it appears as a traveling ionospheric disturbance (TID). On 4 April 2014 concentric GW ring patterns were seen at stratospheric heights in close proximity to a convective storm over North Texas in the Atmospheric Infrared Sounder data on board the NASA Aqua satellite. Concentric GWs of similar orientation and epicenter were also observed in mesospheric nightglow measurements of the Day/Night Band of the Visible/Infrared Imaging Radiometer Suite on the Suomi National Polar-orbiting Partnership satellite. Concentric TIDs were seen in total electron content data derived from ground-based GPS receivers distributed throughout the U.S. These new multisensor observations of TIDs and atmospheric GWs can provide a unique perspective on ionosphere-atmosphere coupling.

  5. 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.

  6. 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 multiple low orbiting satellites have confirmed a significant increase in their intensity over the populated areas of Europe and Asia. Recently, there are many experimental evidences of the existence of power line harmonic radiation (PLHR) in the ionosphere. Their spectra consist of succession of 50 (60) Hz harmonics which is accompanied by a set of lines separated by 50 (60) or 100 (120) Hz - the central frequency of which is shifted to high frequency. These lines cover rather wide band - according to the available experimental data, their central frequencies are observed from ~1.5 - 3 kHz up to 15 kHz, and recently the main mains frequencies are also observed. The examples of power line harmonic radiation, which were detected by “Sich-1M”, “Chibis-M” and “Demeter” satellites, have been presented and discussed. The available experimental data, as well as theoretical estimations, allow us with a high degree of certainty to say that the permanent satellite monitoring of the ionospheric and magnetospheric anthropogenic EM perturbations is necessary for: a) objective assessment and prediction of the space weather conditions; b) evaluation of the daily or seasonal changes in the level of energy consumption; c) construction of a map for estimation of near space EM pollution. This study is partially supported by SSAU contract N 4-03/13.

  7. 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.

  8. 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.

  9. 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 studies and improvements, enabling the integration of lateral variations of the solid earth, bathymetry or atmosphere, finite model sources, non-linearity of the waves and better attenuation and coupling processes. All these effects are revealed by phase or amplitude discrepancies in selected observations. We then present goals and first results of source inversions, with a focus on estimations of the sea level uplift location and amplitude, either by using GPS networks close from the epicentre or, for tsunamis, GPS of the Hawaii Islands.

  10. Survey of the ionospheric disturbances related with large seismic events in multi-satellite ionospheric observations

    NASA Astrophysics Data System (ADS)

    Ryu, K.; Chae, J.; Lee, E.; Kil, H.

    2013-12-01

    We survey the ionospheric disturbances in the plasma and electro-magnetic wave measurements during the simultaneous observation period of DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions), CHAMP (CHAllenging Minisatellite Payload) and DMSP(Defense Meteorological Satellite Program) missions. The multi-satellite observation around three large earthquakes that occurred between 2004 and 2005 were investigated. The observational evidences of the earth-quake precursory phenomena and the recent progress of physical modeling of the ionospheric disturbances caused by the coupling of the stressed rock, Earth surface charges, atmosphere, and ionosphere system are reviewed. Then, we focus on identifying the precursory disturbances from the well-studied plasma disturbances in the ionosphere, which are known to originate from various physical mechanism other than the seismic activities. Electron density/temperature, ion density/temperature, and electro-magnetic field/wave data measured by various instruments equipped in the satellites were analyzed in finding specific examples of anomaly caused by large seismic activities. Finally, the possibility of forecasting or predicting large earthquakes using the plasma measurements of LEO (low earth orbit) satellites will be discussed.

  11. 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.

  12. Self-excitation of auroral arcs in a three-dimensionally coupled magnetosphere-ionosphere system

    NASA Technical Reports Server (NTRS)

    Watanabe, Kunihiko; Sato, Tetsuya

    1988-01-01

    This paper presents the first full three-dimensional dynamic simulation of auroral arc formation. The magnetospheric and ionospheric dynamics are represented by one-fluid magnetohydrodynamic equations and two-fluid weakly ionized plasma equations, respectively. The feedback coupling between magnetospheric Alfven waves and ionospheric density waves results in a spontaneous generation of longitudinally elongated striations of field-aligned currents and ionospheric electron densities, which compare very well with many features of quiet auroral arcs.

  13. The upper ionospheres of Jupiter and Saturn

    NASA Technical Reports Server (NTRS)

    Majeed, Tariq; Mcconnell, John C.

    1991-01-01

    The electron-density profiles of Jupiter's and Saturn's ionospheres are modeled with a 1D chemical diffusive model incorporating measured parameters of the neutral atmospheric structure. The Voyager RSS ion-density data are modeled by accounting for ion chemistry, the H3(+) recombination-rate coefficient, and H2O chemistry. Electron-density peaks for both ionospheres are 900-1000 km lower in the model than the measured values, and the role of vibrational excitation of H2 is discussed in converting H(+) to H2(+) and H3(+). Vertical ion flow is also considered which can maintain the plasma peaks under the conditions of electrical fields or horizontal neutral winds. An assumed influx of H2O molecules of a specific quantity is theorized to reproduce the measured values on Saturn when combined with a vertical plasma drift.

  14. 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 , U., Krishan, V., Singh, J., Srikanth, R., 2004, MNRAS, 347, 1279-12814) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2005, Solar Physics, 231, 1-105) Paniveni , U., Krishan, V., Singh, J., Srikanth, R., 2010, MNRAS, 402, Issue 1, 424-428

  15. Electron densities and temperatures in the Venus ionosphere Effects of solar EUV, solar wind pressure and magnetic field

    NASA Technical Reports Server (NTRS)

    Elphic, R. C.; Russell, C. T.; Brace, L. H.

    1985-01-01

    The Venus ionosphere is influenced by variations in both solar EUV flux and solar wind conditions. On the dayside the location of the topside of the ionosphere, the ionopause, is controlled by solar wind dynamic pressure. Within the dayside ionosphere, however, electron density is affected mainly by solar EUV variations, and is relatively unaffected by solar wind variations and associated magnetic fields induced within the ionosphere. The existence of a substantial nightside ionosphere of Venus is thought to be due to the rapid nightward transport of dayside ionospheric plasma across the terminator. Typical solar wind conditions do not strongly affect this transport and consequently have little direct influence on nightside ionospheric conditions, except on occasions of extremely high solar wind dynamic pressure. However, both nightside electron density and temperature are affected by the presence of magnetic field, as in the case of ionospheric holes.

  16. Theory and experimental evaluation of a consistent steady-state kinetic model for two-dimensional conductive structures in ionospheric plasmas with application to bare electrodynamic tethers in space

    NASA Astrophysics Data System (ADS)

    Choiniere, Eric

    A steady-state kinetic computational model is developed, allowing for self-consistent simulations of collisionless, unmagnetized flowing plasmas in a vast region surrounding any two-dimensional conductive object. An optimization approach is devised based on a stable, noise-robust Tikhonov-regularized Newton method. Dynamic, adaptive, unstructured meshing allows arbitrary geometries and adequate resolution of plasma sheath features. A 1-D cylindrical solver (KiPS-1D) and a full 2-D solver (KiPS-2D) were developed, the latter using coarse-grained parallelism. This technique is applied to investigate various applications of special and fundamental importance, principally for space plasmas, although not limited as such. This thesis addresses new simulations and experiments relevant to space borne electrodynamic tethers for propellantless propulsion and for the remediation of radiation belts through charge precipitation, as well as to Langmuir probes for plasma diagnostic in flowing plasmas. Here, the existing set of plasma sheath profiles and current collection characteristics for round cylinders in stationary plasmas is extended to large bias potentials. Interference effects between two parallel cylinders are shown to exist for spacings upward of 20 times the single-cylinder sheath radius, and an optimal spacing equal to the single-cylinder sheath radius maximizes the sheath area, a finding qualitatively supported by our new experimental data on electron-collecting thin slotted tapes. Also, a thin conductive solid tape is shown to have an equal-capacitance circular radius of about 0.29 times its width. Its predicted collected current characteristic as a function of width approximately agrees with experimental measurements. Further, it has a lower current collection capability than the equal-capacitance circular cylinder. For ion-attracting cylinders, ionospheric plasma representative of an altitude of 1500 km with a flow energy on the order of the thermal energy is shown to cause significant sheath asymmetries, reducing the sheath radius and current collection by about 30%. For electron-attracting cylinders, a mesosonic flow is experimentally shown to significantly enhance electron collection. This cannot be predicted by a collisionless model and may be due to an elongation of the ram-side pre-sheath into a collisional zone for electrons.

  17. 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.

  18. The Comprehensive Inner Magnetosphere-Ionosphere Model

    NASA Astrophysics Data System (ADS)

    Fok, M.-C.; Buzulukova, N. Y.; Chen, S.-H.; Glocer, A.; Nagai, T.; Valek, P.; Perez, J. D.

    2014-09-01

    Simulation studies of the Earth's radiation belts and ring current are very useful in understanding the acceleration, transport, and loss of energetic particles. Recently, the Comprehensive Ring Current Model (CRCM) and the Radiation Belt Environment (RBE) model were merged to form a Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. CIMI solves for many essential quantities in the inner magnetosphere, including ion and electron distributions in the ring current and radiation belts, plasmaspheric density, Region 2 currents, convection potential, and precipitation in the ionosphere. It incorporates whistler mode chorus and hiss wave diffusion of energetic electrons in energy, pitch angle, and cross terms. CIMI thus represents a comprehensive model that considers the effects of the ring current and plasmasphere on the radiation belts. We have performed a CIMI simulation for the storm on 5-9 April 2010 and then compared our results with data from the Two Wide-angle Imaging Neutral-atom Spectrometers and Akebono satellites. We identify the dominant energization and loss processes for the ring current and radiation belts. We find that the interactions with the whistler mode chorus waves are the main cause of the flux increase of MeV electrons during the recovery phase of this particular storm. When a self-consistent electric field from the CRCM is used, the enhancement of MeV electrons is higher than when an empirical convection model is applied. We also demonstrate how CIMI can be a powerful tool for analyzing and interpreting data from the new Van Allen Probes mission.

  19. Inertial Currents in Isotropic Plasma

    NASA Technical Reports Server (NTRS)

    Heinemann, M.; Erickson, G. M.; Pontius, D. H., Jr.

    1993-01-01

    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 plasma, 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, MED plasma. Solutions are developed by taking the MHD limit of 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.

  20. 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