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Sample records for ionospheric plasma convection

  1. Hemispheric Effects in Ionospheric Plasma Convection and Irregularity Occurrence

    NASA Astrophysics Data System (ADS)

    Ruohoniemi, J. M.; Baker, J. B. H.; Bristow, W. A.; Shepherd, S. G.; Kunduri, B.; Cousins, E. D. P.

    2014-12-01

    Extensive statistical studies have demonstrated the extent of asymmetries between the hemispheres in terms of the global pattern of plasma convection in the high-latitude ionosphere. However, relatively little is known about the asymmetries that arise on meso and smaller spatial scales or in the course of reconfiguration of the global convection following changes in IMF or substorm onsets. Moreover the correspondence between the hemispheres in space weather effects such as the occurrence of ionospheric plasma irregularities is almost unexplored. Some of the challenges in conducting such studies are traceable to more limited observational capabilities in the southern hemisphere. New capabilities have recently been achieved with the expansion of the SuperDARN radar network such that simultaneous and quasi-conjugate coverage is sometimes possible from midlatitudes to the polar cap. We review findings on the asymmetric aspects of high-latitude convection and press further to consider evidence of correspondence and asymmetry in convection when varying in time and across the equatorward auroral and midlatitude regions where conjugacy should obtain more reliably. We also discuss evidence of correlation between the hemispheres in terms of the occurrence of small-scale irregularities as a space weather phenomenon of practical importance.

  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. Ionospheric convection signatures and magnetic field topology

    NASA Technical Reports Server (NTRS)

    Coley, W. R.; Heelis, R. A.; Hanson, W. B.; Reiff, P. H.; Sharber, J. R.

    1987-01-01

    A statistical study of signatures of the high-latitude ionospheric convection pattern and the simultaneously observed energetic electron precipitation is presented. Most often found are convection cells in which the sunward flowing region contains auroral particle precipitation but the antisunward flowing region does not. However, observations also show the frequent occurrence of convection cells in which neither the antisunward nor the sunward flowing plasma region contains auroral particle precipitation. These findings may appear within the dawnside or duskside convection pattern and strongly suggest that such convection cells may be associated with open magnetic field lines that thread the magnetotail lobes.

  4. The excitation of plasma convection in the high-latitude ionosphere

    SciTech Connect

    Lockwood, M. ); Cowley, S.W.H.; Freeman, M.P. )

    1990-06-01

    Recent observations of ionospheric flows by ground-based radars, in particular by the European Incoherent Scatter (EISCAT) facility using the Polar experiment, together with previous analyses of the response of geomagnetic disturbance to variations of the interplanetary magnetic field (IMF), suggest that convection in the high-latitude ionosphere should be considered to be the sum of two intrinsically time-dependent patterns, one driven by solar wind-magnetosphere coupling at the dayside magnetopause, the other by the release of energy in the geomagnetic tail (mainly by dayside and nightside reconnection, respectively). The flows driven by dayside coupling are largest on the dayside, where they usually dominate, are associated with an expanding polar cap area, and are excited and decay on {approximately} 10-min time scales following southward and northward turnings of the IMF, respectively. The latter finding indicates that the production of new open flux at the dayside magnetopause excites magnetospheric and ionospheric flow only for a short interval, {approximately} 10 min, such that the flow driven by this source subsequently decays on this time scale unless maintained by the production of more open flux tubes. Correspondingly, the flows excited by the release of energy in the tail, mainly during substorms, are largest on the nightside, are associated with a contracting polar cap boundary, and are excited on {approximately} 1-hour time scales following a southward turn of the IMF. In general, the total ionospheric flow will be the sum of the flows produced by these two sources, such that due to their different response times to changes in the IMF, considerable variations in the flow pattern can occur for a given direction and strength ofthe IMF. Consequently, the ionospheric electric field cannot generally be regarded as arising from a simple mapping of the solar wind electric field along open flux tubes.

  5. Polar-cap plasma convection measurements and their relevance to the real-time modeling of the high-latitude ionosphere

    SciTech Connect

    Not Available

    1987-05-07

    Plasma-convection measurements, using Digisonde ionospheric sounders, were conducted. The plasma convection or ionospheric-drift measurements conducted at Thule and Qaanaaq during campaigns from Winter 1983/84 to present provide evidence, that antisunward convection dominates in the polar cap with velocities typical between 300 and 900 m.sec. Drift shears were observed during periods of arc-transition (quiet magnetic conditions). Observations of the plasma drift at Goose Bay show a drift reversal from westward to eastward around midnight CGLT. Observations at Argentia, typically a suboval/trough station, provide evidence under magnetically disturbed conditions for the midnight reversal of the antisunward flow pattern. However, the data are less consistent under magnetically quiet conditions. The proximity of the station to the boundary between corotating and convecting plasma may at times affect the consistency of the measurements. Recent theoretical calculations of electron density profiles within the high-latitude/polar-cap ionosphere demonstrate that the diurnal foF2 variation observed at Thule, is controlled by the plasma-convections pattern and the associated drift velocities. The model calculations for Bz < 0 and Bz. approx. 0 show factor 2 to 3 differences in Nmax over Thule, supporting the stated importance of convection pattern and velocity measurements for the modelling of the high-latitude ionosphere.

  6. 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.

  7. 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.

  8. Convective cell generation by kinetic Alfven wave turbulence in the auroral ionosphere

    SciTech Connect

    Zhao, J. S.; Wu, D. J.; Yu, M. Y.; Lu, J. Y.

    2012-06-15

    Modulation of convective cells by kinetic Alfven wave (KAW) turbulence is investigated. The interaction is governed by a nonlinear dispersion relation for the convective cells. It is shown that KAW turbulence is disrupted by excitation of the large-scale convective motion through a resonant instability. Application of the results to the auroral ionosphere shows that cross-scale coupling of the KAW turbulence and convective cells plays an important role in the evolution of ionospheric plasma turbulence.

  9. 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.

  10. Can the ionosphere regulate magnetospheric convection?

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.; Kennel, C. F.

    1972-01-01

    Following a southward shift of the interplanetary magnetic field, which implies enhanced reconnection at the nose of the magnetosphere, the magnetopause shrinks from its Chapman-Ferraro equilibrium position. If the convective return of magnetic flux to the magnetopause equalled the reconnection rate, the magnetopause would not shrink. Consequently, there is a delay in the development of magnetospheric convection following the onset of reconnection, which is ascribed to line tying by the polar cusp ionosphere. A simple model relates the dayside magnetopause displacement to the currents feeding the polar cap ionosphere, from which the ionospheric electric field, and consequently, the flux return rate, may be estimated as a function of magnetopause displacement. Flux conservation arguments then permit an estimate of the time scale on which convection increases, which is not inconsistent with that of the substorm growth phase.

  11. Ionospheric convection associated with discrete levels of particle precipitation

    SciTech Connect

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

    1986-07-01

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

  12. 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.

  13. Mapping ionospheric convection patterns to the magnetosphere

    NASA Astrophysics Data System (ADS)

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

    1995-02-01

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

  14. 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.

  15. Ionospheric plasma cloud dynamics

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Measurements of the thermospheric neutral wind and ionospheric drift made at Eglin AFB, Florida and Kwajalein Atoll are discussed. The neutral wind measurements at Eglin had little variation over a period of four years for moderate magnetic activity (Kp 4); the ionospheric drifts are small. Evidence is presented that indicates that increased magnetic activity has a significant effect on the neutral wind magnitude and direction at this midlatitude station. The neutral wind at dusk near the equator is generally small although in one case out of seven it was significantly larger. It is described how observations of large barium releases can be used to infer the degree of electrodynamic coupling of ion clouds to the background ionosphere. Evidence is presented that indicates that large barium releases are coupled to the conjugate ionosphere at midlatitudes.

  16. 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.

  17. 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.

  18. 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.

  19. Ionospheric anomalous disturbance during the tropospheric strong convective weather

    NASA Astrophysics Data System (ADS)

    Cang, Zhongya; Cheng, Guangguang; Cheng, Guosheng

    2015-07-01

    Based on TBB data from Chinese FY-2 geostationary satellite, NCEP Reanalysis data and GPS-TEC data provided by IGS, by using sliding mean method, ionospheric anomalous disturbance during a typical convective weather was investigated. Results show that this severe convective weather was caused by a high-altitude cold eddy and a strong squall line. The ionospheric total electron content increased abnormally when convection occurred. The maximum increase of tested point was more than 6 TECU mainly at 8-12 UT of the day, and the peak time of the day lagged about 2 h than usual. Ionospheric anomalous region reached about 20 longitudes and 10 latitudes, and anomalous center was on the west side of the convective cloud, which may be related to the topographic effect of the Tibetan Plateau. Series of Case Studies further determine that convective weather can influence the ionospheric state. Furthermore, tropospheric vertical velocity was also analyzed to discuss the possible mechanisms of troposphere-ionosphere coupling.

  20. Ionospheric Conductance During Substorms and Steady Magnetospheric Convection Events (SMCs)

    NASA Astrophysics Data System (ADS)

    DeJong, A. D.; Ridley, A. J.; Bell, J. M.

    2014-12-01

    We will investigate the differences in ionospheric conductance derived from empirical models and simulated by self-consistent ionosphere-thermosphere models, during both substorms and steady magnetospheric convection events. The Global Ionosphere-Thermosphere Model (GITM) will self-consistently calculate the integrated electron content and ionospheric conductance using different energy deposition models and data--such as Ovation, AMIE, and auroral images. We will calculate the average auroral energy deposition and auroral energy flux, using images from the ultraviolet imager (UVI) onboard the Polar spacecraft. From these images, we will use the Robinson empirical formula to calculate the conductance during these different events. We will investigate the similarities and differences in the ionospheric conductance derived from the different methods and derived different event types.

  1. 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;

  2. 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.

  3. 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.

  4. Radar Observations of Interhemispheric Ionospheric Convection Morphology Associated with Magnetotail Dynamics

    NASA Astrophysics Data System (ADS)

    Grocott, A.

    2014-12-01

    We discuss radar observations of the high-latitude ionospheric convection, in both the northern and southern hemispheres, in terms of the interplanetary magnetic field (IMF) orientation, prevailing geomagnetic conditions, and their associated timescales. Plasma velocity measurements, obtained by the Super Dual Auroral Radar Network (SuperDARN), have been used to derive patterns of the ionospheric electric potential in which interhemispheric asymmetries in the associated large-scale convection morphology are identified. In addition to the expected IMF BY-related asymmetries between the dusk and dawn convection cells, which tend to display the opposite sense in the two hemispheres, we find asymmetries related to magnetotail dynamics that exhibit a more complex behaviour. We attribute this to differences in the timescales required for the development of IMF-related asymmetries, and those associated with internal magnetospheric processes. We consider how the interplay between the magnetospheric regions involved determines the overall morphology of the system.

  5. The relationship between ionospheric convection and magnetic activity

    SciTech Connect

    Shue, J.H.; Weimer, D.R. )

    1994-01-01

    In this paper, the authors show that there is a significant relationship between magnetic activity and the high-latitude ionospheric convection electric fields. In particular, when the westward electrojet is much stronger than the eastward electrojet, as occurs during magnetospheric substorms, the electric field patterns show subtle, but important, changes from the configurations that are obtained under more quiet conditions. The substorm differences are detected primarily near midnight, where there is an enhanced westward electric field associated with a penetration of the positive-potential, dawn convection cell into the negative, dusk convection cell. The peak value of the positive potential also increases during substorms and its location shifts closer to midnight, while the negative cell remains relatively constant. These results were obtained through the use of a procedure that uses electric field measurements from the DE 2 satellite to derive maps of the locations of the convection reversal boundaries, and functions for the distribution of the electric potential around these boundaries. This was accomplished for several sets of data that were grouped according to the interplanetary magnetic field and geomagnetic activity. Further refinements in the authors' analysis procedure are possible. The results could be used to produce more accurate maps of ionospheric convection. They also show that distortions of the electric field patterns near midnight are simply the result of polarization electric fields around conductivity enhancements. The distorted electric fields satisfy the condition that the ionospheric Hall current be divergence-free. 23 refs., 9 figs.

  6. Ground-based studies of ionospheric convection associated with substorm expansion

    SciTech Connect

    Kamide, Y. |; Richmond, A.D.; Emery, B.A.; Hutchins, C.F.; Ahn, B.H. |; Beaujardiere, O. de la; Foster, J.C.; Heelis, R.A.; Kroehl, H.W.; Rich, F.J.

    1994-10-01

    The instantaneous patterns of electric fields and currents in the high-latitude ionosphere are deduced by combining satellite and radar measurements of the ionospheric drift velocity, along with ground-based magnetometer observations for October 25, 1981. For this purpose, an updated version of the assimilative mapping of ionospheric electrodynamics technique has been used. These global patterns are unobtainable from any single data set. The period under study was characterized by a relatively stable southward interplanetary magnetic field (IMF), so that the obtained electric field patterns do reflect, in general, the state of sustained and enhanced plasma convection in the magnetosphere. During one of the satellite passes, however, an intense westward electrojet caused by a substorm intruded into the satellite (DE 2) and radar (Chatanika, Alaska) field of view in the premidnight sector, providing a unique opportunity to differentiate the enhanced convection and substorm expansion fields. The distributions of the calculated electric potential for the expansion and maximum phases of the substorm show the first clear evidence of the coexistence of two physically different systems in the global convection pattern. The changes in the convection pattern during the substorm indicate that the large-scale potential distributions are indeed of general two-cell patterns representing the southward IMF status, but the night-morning cell has two positive peaks, one in the midnight sector and the other in the late morning hours, corresponding to the substorm expansion and the convection enhancement, respectively. 40 refs., 12 figs., 1 tab.

  7. Ground-based studies of ionospheric convection associated with substorm expansion

    SciTech Connect

    Kamide, Y.; Richmond, A.D.; Emery, B.A.; Hutchins, C.F.; Ahn, B.H.

    1994-10-01

    The instantaneous patterns of electric fields and currents in the high-latitude ionosphere are deduced by combining satellite and radar measurements of the ionospheric drift velocity, along with ground-based magnetometer observations for October 25, 1981. For this purpose, an updated version of the assimilative mapping of ionospheric electrodynamics technique has been used. These global patterns are unobtainable from any single data set. The period under study was characterized by a relatively stable southward interplanetary magnetic field (IMF), so that the obtained electric field patterns do reflect, in genernal, the state of sustained and enhanced plasma convection in the magnetosphere. During one of the satellite passes, however, an intense westward electrojet caused by a substorm intruded into the satellite (DE 2) and radar (Chatanika, Alaska) field of view in the premidnight sector, providing a unique opportunity to differentiate the enhanced convection and substorm expansion fields. The distributions of the calculated electric potential for the epansion and maximum phases of the substorm show the first clear evidence of the coezistence of two physically different systems in the global convection pattern. The changes in the convection pattern during the substorm indicate that the large-scale potential distributions are indeed of general two-cell patterns representing the southward LMF status, but the night-morning cell has two positive peaks, one in the midnight sector and the other in the late morning hours, corresponding to the substorm expansion and the convection enhancement respectively.

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. Tropical convection, ionospheric potentials and global circuit variation

    NASA Technical Reports Server (NTRS)

    Markson, R.

    1986-01-01

    The ionospheric potential (VI), a measure of the earth's overall electric field intensity, correlates with the classic 'Carnegie curve' diurnal variation in electric field caused by the global distribution of thunderstorms. A comparison of VI variation with satellite images of high tropical cloud fields indicates that equatorial thunderstorms over the continents are dominant in maintaining the earth's electric field. VI time series obtained at just one location may provide a high-resolution measure of intense tropical convection.

  12. Plasma jet effects on the ionospheric plasma

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    Heavy ion beams were injected into the ionospheric plasma (experiments ARCS 1 and ARCS 2). In ARCS 1, operation of a 25eV argon ion source, mounted on a plasma diagnostic payload, produced an accelerated electron population; broadband electric field turbulence; large, spin synchronized electric field perturbations; and depletions of thermal ions. In ARCS 2, the ion source was deployed upward along the local magnetic field direction away from the diagnostic payload, and observed effects are contained within several meters of the ion source. However, enhanced wave levels near the LHR frequency are observed at distances up to 1 km, as are the injected ions themselves. A measurement of the dominant wavelength of the enhanced waves is consistent with an inference based upon the accelerated electron population seen in ARCS 1. This electron population is not evident during ARCS 2.

  13. 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.

  14. Interhemispheric differences in ionospheric convection: Cluster EDI observations revisited

    NASA Astrophysics Data System (ADS)

    Frster, M.; Haaland, S.

    2015-07-01

    The interaction between the interplanetary magnetic field and the geomagnetic field sets up a large-scale circulation in the magnetosphere. This circulation is also reflected in the magnetically connected ionosphere. In this paper, we present a study of ionospheric convection based on Cluster Electron Drift Instrument (EDI) satellite measurements covering both hemispheres and obtained over a full solar cycle. The results from this study show that average flow patterns and polar cap potentials for a given orientation of the interplanetary magnetic field can be very different in the two hemispheres. In particular during southward directed interplanetary magnetic field conditions, and thus enhanced energy input from the solar wind, the measurements show that the southern polar cap has a higher cross polar cap potential. There are persistent north-south asymmetries, which cannot easily be explained by the influence of external drivers. These persistent asymmetries are primarily a result of the significant differences in the strength and configuration of the geomagnetic field between the Northern and Southern Hemispheres. Since the ionosphere is magnetically connected to the magnetosphere, this difference will also be reflected in the magnetosphere in the form of different feedback from the two hemispheres. Consequently, local ionospheric conditions and the geomagnetic field configuration are important for north-south asymmetries in large regions of geospace.

  15. 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.

  16. Magnetospheric convection from Cluster EDI measurements compared with the ground-based ionospheric convection model IZMEM

    NASA Astrophysics Data System (ADS)

    Frster, M.; Feldstein, Y. I.; Haaland, S. E.; Dremukhina, L. A.; Gromova, L. I.; Levitin, A. E.

    2009-08-01

    Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for more than seven and a half years (2001-2008) have been used to derive a statistical model of the high-latitude electric potential distribution for summer conditions. Based on potential pattern for different orientations of the interplanetary magnetic field (IMF) in the GSM y-z-plane, basic convection pattern (BCP) were derived, that represent the main characteristics of the electric potential distribution in dependence on the IMF. The BCPs comprise the IMF-independent potential distribution as well as patterns, which describe the dependence on positive and negative IMFBz and IMFBy variations. The full set of BCPs allows to describe the spatial and temporal variation of the high-latitude electric potential (ionospheric convection) for any solar wind IMF condition near the Earth's magnetopause within reasonable ranges. The comparison of the Cluster/EDI model with the IZMEM ionospheric convection model, which was derived from ground-based magnetometer observations, shows a good agreement of the basic patterns and its variation with the IMF. According to the statistical models, there is a two-cell antisunward convection within the polar cap for northward IMFBz+?2 nT, while for increasing northward IMFBz+ there appears a region of sunward convection within the high-latitude daytime sector, which assumes the form of two additional cells with sunward convection between them for IMFBz+?4-5 nT. This results in a four-cell convection pattern of the high-latitude convection. In dependence of the IMFBy contribution during sufficiently strong northward IMFBz conditions, a transformation to three-cell convection patterns takes place.

  17. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  19. 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.

  20. 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.

  1. 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.

  2. Large scale plasma irregularities and airglow enhancements from ionospheric heating

    NASA Astrophysics Data System (ADS)

    Bernhardt, Paul A.; Rowland, Harvey; Duncan, Lewis M.; Tepley, Craig A.

    1990-10-01

    Ionospheric modification with high power radio waves may generate plasma irregularities and airglow clouds. Large scale irregularities are produced in a convecting F-layer by a mechanism called the plasma relaxation oscillator. When a continuous beam of powerful electromagnetic waves heats the ionosphere, a cavity is produced by thermal pressure gradients. The cavity drifts under the influence of ambient electric fields causing the vertically-incident, radio beam to be refracted from the zenith. At some point, the cavity can no longer 'capture' the beam and it returns to the zenith to form another cavity. This relaxation process repeats to yield irregularities on the scale of the heater beam diameter. Airglow enhancements are produced by energetic electrons accelerated out of the heated region. Large amplitude electrostatic waves may be excited by linear mode coupling, by parametric decay instabilities, and by strong plasma turbulence. This occurs near the point where the plasma frequency of the ionosphere matches wave frequency. The electrostatic waves accelerate ambient electrons to high enough energy to collisionally excite ambient oxygen atoms. Clouds of enhanced red-line (630.0 nm) and green-line (557.7 nm) emissions were recorded with low-light-level imaging systems located at Arecibo, Puerto Rico. Comparison of the imager data with data from the Arecibo incoherent scatter radar shows that artificial airglow clouds are physically tied to the density cavities and to regions of enhanced electrostatic waves by the earth's magnetic field lines. At currently available power levels (around 80 MW effective radiated power), HF modification yields 10-30 percent fluctuations in density and 10-100 Rayleigh enhancements in airglow intensity.

  3. 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 Alfvnic 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.

  4. Explosive plasma releases in the earth's ionosphere

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.

    1982-01-01

    The Trigger and Buaro experiments and the University of Alaska's radial shaped charge experiment, which were conducted to actively probe the ionosphere with expanding plasmas are described. Emphasis is on the Trigger experiment, which has a Cs release with spherical geometry. Transient events occurring after Cs detonation include the production of a 200 mV/m electric field pulse, and the precipitation of energetic electrons. Future applications are also discussed, and include in situ measurements of the radial shaped experiment from a mother-daughter payload.

  5. 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.

  6. 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.

  7. 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.

  8. Rocket vehicle targeting for the PLACES ionospheric plasma test series

    NASA Astrophysics Data System (ADS)

    Rollstin, L. R.

    1984-02-01

    The PLACES (Position Location And Communication Effects Simulations) test program, conducted in December 1980 at Eglin Gulf Test Range, involved a series of ionospheric releases of barium/barium-nitrate vapor. The Defense Nuclear Agency sponsored program investigated effects of a structured ionospheric plasma (similar to that produced by a high-altitude nuclear explosion) on satellite navigation systems and provided in situ measurement of plasma structure. Terrier-Tomahawk rocket systems boosted the barium payloads, beacon payloads (plasma occultation experiment), and probe payloads (plasma in situ measurement). Drifting plasma tracking procedures, beacon- and probe-vehicle targeting procedures, and vehicle flight test results are presented.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Plasma convection in the magnetotail lobes: statistical results from Cluster EDI measurements

    NASA Astrophysics Data System (ADS)

    Haaland, S.; Paschmann, G.; Frster, M.; Quinn, J.; Torbert, R.; Vaith, H.; Puhl-Quinn, P.; Kletzing, C.

    2008-08-01

    A major part of the plasma in the Earth's magnetotail is populated through transport of plasma from the solar wind via the magnetotail lobes. In this paper, we present a statistical study of plasma convection in the lobes for different directions of the interplanetary magnetic field and for different geomagnetic disturbance levels. The data set used in this study consists of roughly 340 000 one-minute vector measurements of the plasma convection from the Cluster Electron Drift Instrument (EDI) obtained during the period February 2001 to June 2007. The results show that both convection magnitude and direction are largely controlled by the interplanetary magnetic field (IMF). For a southward IMF, there is a strong convection towards the central plasma sheet with convection velocities around 10 km s-1. During periods of northward IMF, the lobe convection is almost stagnant. A By dominated IMF causes a rotation of the convection patterns in the tail with an oppositely directed dawn-dusk component of the convection for the northern and southern lobe. Our results also show that there is an overall persistent duskward component, which is most likely a result of conductivity gradients in the footpoints of the magnetic field lines in the ionosphere.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Lu, G.

    2014-12-01

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

  16. Polar Cap Convection Structures: Relations to High Speed Streams and Plasma Sheet Dynamics

    NASA Astrophysics Data System (ADS)

    Lyons, L. R.; Nishimura, T.; Kim, H.; Angelopoulos, V.; Heinselman, C. J.; Ruohoniemi, J. M.; Sofko, G. J.; Donovan, E.

    2011-12-01

    The orientation and magnitude of the interplanetary magnetic field (IMF) and solar wind dynamic pressure are well known to affect the strength of convection. However, radar measurements of high-latitude ionospheric convection show evidence that ULF power in the IMF 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. Convection flows during periods of large north-south IMF fluctuations are observed to be as strong as for steady and large southward IMF periods, and substantially enhanced convection is observed for northward IMF intervals when the IMF exhibits high ULF power. Since ULF power is particularly high during high-speed solar wind streams (HSS), these effects are particularly important and likely a major contributor to disturbances within the magnetosphere-ionosphere-thermosphere system during HSS. However, observations during periods of Alfvnic magnetic fluctuations without high-speed solar wind indicate that the enhanced flows are at least in part directly due to the Alfvnic magnetic fluctuations and are not solely due to the high-speed solar wind. We furthermore find that the enhanced polar-cap convection driven by the ULF power in the solar wind is highly structured in time, and is associated with many substorms, including during periods of northward IMF. A possible cause of the connection to convection and disturbances within the plasma sheet is indicated by recent radar observations of flows within the polar cap. The observations suggest that meso-scale flow channels from deep within the region of open polar cap field lines may cross the nightside polar cap boundary into the closed field line region and contribute to the triggering of equatorward (earthward) meso-scale flows across the ionospheric (equatorial) end of plasma sheet fields lines and lead to PBIs and streamers. This includes the streamers that have been postulated to bring new plasma equatorward (earthward) and lead to substorm onset. Such a connection offers an explanation for the enhanced convection, plasma pressures, and substorm activity that has been observed within the plasma sheet during periods of enhanced ULF fluctuations, including during HSS.

  17. 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.

  18. 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.

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

    SciTech Connect

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

    1986-04-11

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

  20. Kinetic modeling of the Saturn ring-ionosphere plasma environment

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

    A time-independent kinetic plasma model was developed on the basis of the Li et al. (1988) semikinetic plasma model and was used to study the interaction of the Saturnian ionosphere and ring plasma. The model includes the gravitational magnetic mirror and centripetal and ambipolar electric forces, and the effect of the mixing of two plasma populations. The results obtained indicate that the density, temperature, and composition of plasma near the rings changing in the direction from the inner C ring to the outer A ring, due to the fact that the predominant source of plasma changes from the ionosphere to the rings. The model results also suggest that the outflow of hydrogen from the ionosphere to the rings may be shut off for field lines passing through the outer B and A ring, due to the ambipolar electric field set up by the warm ring plasma trapped near the ring plane by the centipetal force. In these regions, there will be a net flux of O(+) ions from the rings to the ionosphere.

  1. 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.

  2. Ionospheric convection signatures observed by DE 2 during northward interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.; Hanson, W. B.; Reiff, P. H.; Winningham, J. D.

    1986-01-01

    Observations of the ionospheric convection signature at high latitudes are examined during periods of prolonged northward interplanetary magnetic field (IMF). The data from Dynamics Explorer 2 show that a four-cell convection pattern can frequently be observed in a region that is displaced to the sunward side of the dawn-dusk meridian regardless of season. In the eclipsed ionosphere, extremely structured or turbulent flow exists with no identifiable connection to a more coherent pattern that may simultaneously exist in the dayside region. The two highest-latitude convection cells that form part of the coherent dayside pattern show a dependence on the y component of the IMF. This dependence is such that a clockwise circulating cell displaced toward dawn dominates the high-latitude region when B(Y) is positive. Anti-clockwise circulation displaced toward dusk dominates the highest latitudes when B(Y) is negative. Examination of the simultaneously observed energetic particle environment suggests that both open and closed field lines may be associated with the high-latitude convection cells. On occasions these entire cells can exist on open field lines. The existence of closed field lines in regions of sunward flow is also apparent in the data.

  3. Vertical sheets of dense plasma in the topside Martian ionosphere

    NASA Astrophysics Data System (ADS)

    Nielsen, E.; Wang, X.-D.; Gurnett, D. A.; Kirchner, D. L.; Huff, R.; Orosei, R.; Safaeinili, A.; Plaut, J. J.; Picardi, G.

    2007-02-01

    The low-frequency radar, Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), on board the Mars Express spacecraft is used to sound electron densities in the topside Martian ionosphere. The radar records the delay times to echoes of reflected radio waves as a function of frequency, yielding spectrograms with traces of radar echoes. At times, two traces are present in spectrograms of the Martian ionosphere. One of these traces corresponds to reflections from the direction to nadir. The other trace originates in a localized reflector in the ionosphere. The local reflectors can be associated with the cusplike regions of near-vertical crustal magnetic fields. The apparent nadir angle of reflection can occasionally increase to 90. This suggests that steep gradients of the altitude of the electron isodensity exist in the Martian ionosphere and indicates rapid horizontal spatial variations of vertical diffusion of Martian plasma. Such gradients may arise owing to preferential access of solar wind to the cusplike regions or to precipitation of energetic electrons from acceleration regions located on cusp magnetic field lines high above the ionosphere.

  4. Contribution of low-energy ionospheric protons to the plasma sheet

    NASA Technical Reports Server (NTRS)

    Delcourt, D. C.; Moore, T. E.; Chappell, C. R.

    1994-01-01

    The magnetospheric transport of low-energy ionospheric ions is examined by means of three-dimensional particle codes. Emphasis is placed on the behavior of polar wind and cleft originating protons. It is demonstrated that, via nonadiabatic motion inside the neutral sheet, these ions can significantly contribute to the populations of the plasma sheet. The importance of this contribution is found to depend critically upon the dynamics of particles originating from the highest latitudes, as these possibly have access to the distant tail. Hence it is shown that polar wind H(+) expelled into the magnetosphere at very low energies (in the electron volt range) preferentially feed the plasma sheet during quiet times, experiencing accelerations up to several kiloelectron volts upon return into the inner magnetosphere. In contrast, during disturbed times, the intensifying magnetospheric convection confines this population to low L shells where it travels in a nearly adiabatic manner. As for the protons originating from the cleft fountain, the simulations reveal that they can be transported up to the vicinity of the distant neutral line in the nightside sector. Via interaction with the neutral sheet, these ionospheric ions are rapidly raised to the characteristic plasma sheet energy range. The density levels contributed by these populations are quite substantial when compared to those measured in situ. These simulations establish an active role of low-energy ionospheric ions in the overall magnetospheric dynamics.

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

    NASA Technical Reports Server (NTRS)

    Kivanc, O.; Heelis, R. A.

    1998-01-01

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

  6. 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.

  7. 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.

  8. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  10. Conversion of ionospheric heater HF waves into electron acoustic waves in warm ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Lehtinen, N. G.; Inan, U. S.; Bunch, N. L.

    2012-12-01

    The Stanford full-wave method (StanfordFWM) was developed in order to calculate generation and propagation of electromagnetic waves in cold magnetized stratified plasmas. We generalize it by including the effects of electron temperature, by following a procedure analogous to that of [Budden and Jones, 1987, doi:10.1098/rspa.1987.0077]. The advantage of StanfordFWM is that it is intrinsically numerically stable against ``swamping'' by evanescent waves while in the method of Budden and Jones [1987] ``the problem of numerical swamping is severe ...'' The new method is used to calculate mode conversion between electron acoustic (Langmuir) and electromagnetic modes for propagation in a warm ionospheric plasma with a gradient of electron density and an arbitrary direction of the background geomagnetic field, in the vicinity of density corresponding to the plasma resonance. As a numerical check, we demonstrate good agreement with previous calculations of Budden and Jones [1987] obtained by a numerically-unstable full-wave method scheme; Mjolhus [1990, doi:10.1029/RS025i006p01321] obtained by the method of contour integration in the complex n-plane; and Kim et al [2008, doi:10.1063/1.2994719] using a numerical electron fluid simulation code. We demonstrate that under certain conditions the linear conversion of the ordinary HF electromagnetic waves radiated by an ionospheric heater into electron acoustic waves may be very efficient, with implications for the HF heating of the F-region of ionosphere.

  11. 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

  12. 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.

  13. Stimulated plasma instability and nonlinear phenomena in the ionosphere

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1982-01-01

    Several hundred topside ionograms were used to study simulated wave-particle interactions in the ionosphere. The study combined the benefits of high-frequency-resolution Alouette 2 analog sounder data with advanced digital graphics techniques. The study shows that the sounder phase can cause significant plasma heating when the plasma parameter is confined to specific ranges. The observations support the Harris instability generation process and the nonlinear Landau damping maintaining process for long-duration diffuse resonances. The observations also suggest that the so-called Q resonances have characteristics which imply that generation processes in a sounder-stimulated plasma turbulence may be involved.

  14. 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.

  15. Solar activity variation of ionospheric plasma temperatures

    NASA Technical Reports Server (NTRS)

    Bilitza, D.; Hoegy, W. R.

    1990-01-01

    The present status of understanding and modeling of the variation of electron and ion temperatures with solar activity is reviewed. All atmospheric and ionospheric densities and temperatures are positively correlated with solar activity except the electron temperature, which exhibits a rather complex variation pattern during a solar cycle. The ion temperature at low altitudes closely follows the variation patterns of the neutral temperature. The electron temperature at high altitudes increases with increasing solar activity; the increase is larger during day than during night and exhibits a latitudinal variation. At low altitudes during daytime, tha amplitude of the seasonal variation of the electron temperature increases toward the solar maximum. At 400 km during daytime, the summer electron temperatures for Millstone Hill increase slightly toward higher solar activities, whereas the winter temperatures decrease distinctly. For Arecibo, an opposite trend is noticeable.

  16. Measuring ionospheric electron density using the plasma frequency probe

    NASA Technical Reports Server (NTRS)

    Jensen, Mark D.; Baker, Kay D.

    1992-01-01

    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.

  17. Relation between Localized Ionospheric Convection Variation and Poleward Boundary Identifications (PBIs)

    NASA Astrophysics Data System (ADS)

    Shi, Yong; Zesta, Eftyhia; Lyons, Larry

    We investigate the relation between Poleward Boundary Intensifications (PBIs) and localized variations of ionospheric convection flow by using flow observations from the Sondrestrom in-coherent scatter radar and the SuparDARN radar, and concurrent auroral images from the IMAGE satellite. The PBI signatures are identified in observations from IMAGE Far Ultra-violet Imager (FUV). The corresponding temporal and spatial ionospheric flow variations are examined by inspecting the Sondrestrom and SuperDARN observations. We analyzed a total of 12 events and find that both Sondrestrom and SuperDARN (if any) show enhanced local ionospheric flow for all PBIs. Enhancements are absent in the absence of PBIs. Also, the direction of the enhanced flow generally follows the orientations of the PBIs. In particular, for PBIs occurring in the pre-midnight sector, there generally exists an enhanced flow shear with PBIs very near the center of the shear. For some cases, the 2-D flow observations from SuperDARN clearly show that the flow enhancements are associated with localized change of potential contours at the locations of the PBIs. This indicates the direct mapping of magneto-spheric electric field associated with the tail signature of PBIs (presumably fast flow channels) to the ionosphere, where it disturbs the local potential. Our results also show that there is dis-tinction between cases with substorms and without substorms. For cases with substorms, there are generally PBIs occurring before and after substorm onsets. Eastward flow enhancements are seen before onset and weaker equatorward-dominated flows are seen after onset.

  18. Aurora and convection channel events in response to solar wind - magnetosphere - ionosphere interaction processes (Invited)

    NASA Astrophysics Data System (ADS)

    Sandholt, P. E.; Farrugia, C. J.

    2010-12-01

    We describe the ionospheric manifestations of the temporal-spatial evolution of open magnetic field lines during the first 20 min after the onset of pulsed magnetopause reconnectionevents, appearing in the form of aurora and convection channel events. We then discuss their relevance to our understanding of temporal-spatial structure in the reconnecting magnetosphere. We first distinguish between two consecutive phases of this evolution, depending on time elapsed since reconnection (``newly open''and "old open" field lines). Phase 1 consists of the auroral brightening events appearing on the pre- and postnoon sides of the ``midday gap aurora'' and associated flow channels (FC 1 in our terminology; originally known as pulsed ionospheric flows; PIFs) as described by Southwood (1987). The auroral brightenings in both sectors expand noonward and poleward, followed by a fading phase in the regime of mantle precipitation after appr. 10 min. The later phase 2 (time since reconnection appr. 10-20 min) is characterized by the appearance of a 200-300 km wide channel of enhanced (> 1 km/s) antisunward convection located on the dusk - or dawn side of the polar cap, the location depending on the IMF By polarity. This fast flow appears within the regime of polar rain precipitation. This is our flow channel FC 2. In the case of a By - dominated IMF orientation (|By/Bz| > 1) flow channel FC 2 contributes to extending the dawn-dusk convection asymmetry of polar cap flows tailward of the cusp region. The momentum transfer from high magnetospheric altitudes (cusp dynamo) to the ionosphere is attributed to a system of C1-C2 Birkeland currents (HCC-LCC currents of Taguchi et al., 1993) located poleward of the R1-R2 currents. In many instances a considerable fraction of the CPCP potential is associated with these flow channels. In the case of strongly south IMF orientation (|By/Bz| < 1) a different, more symmetric FC 2 configuration appears, characterized by flow channels on both sides of the polar cap. The FC 2 flow channels appear in the form of events ``directly driven'' by IMF southward turnings or as a sequence of appr. 10 min long ``spontaneous events'' during intervals of quasi-steady IMF orientation. The two phases of the flow evolution (the FC 1 and FC 2 events) in the convection cycle are clearly manifest in ground magnetic deflections. In particular, the Svalgaard-Mansurov effect appearing at longitudes tailward of the cusp is due to Hall currents in FC 2.

  19. Large-scale plasma irregularities and airglow enhancements from ionospheric heating

    SciTech Connect

    Bernhart, P.A.; Rowland, H.

    1990-10-01

    Ionospheric modification with high power radio waves may generate plasma irregularities and airglow clouds. Large scale irregularities are produced in a convecting F-layer by a mechanism called the plasma-relaxation-oscillator. When a continuous beam of powerful electromagnetic waves heats the ionosphere, a cavity is produced by thermal pressure gradients. The cavity drifts under the influence of ambient electric fields causing the vertically-incident, radio beam to be refracted from the zenith. At some point, the cavity can no longer capture the beam and it returns to the zenith to form another cavity. This relaxation process repeats to yield irregularities on the scale of the heater beam diameter. Airglow enhancements are produced by energetic electrons accelerated out of the heated region. Large amplitude electrostatic waves may be excited by linear mode coupling, by parametric decay instabilities, and by strong plasma turbulence. This occurs near the point where the plasma frequency of the ionosphere matches wave frequency. The electrostatic waves accelerate ambient electrons to high enough energy to collisionally excite ambient oxygen atoms. Clouds of enhanced red-line (630.0 nm) and green-line (557.7 nm) emissions have been recorded with low-light-level imaging systems located at Arecibo, Puerto Rico. Comparison of the Imager data with data from the Arecibo incoherent scatter radar shows that artificial airglow clouds are physically tied to the density cavities and to regions of enhanced electrostatic waves by the earth's magnetic field lines. At currently available power levels (around 80 MW effective radiated power), HF modification yields 10-30% fluctuations in density and 10-100 Rayleigh enhancements in airglow intensity.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Ionospheric convection signatures of tail fast flows during substorms and Poleward Boundary Intensifications (PBI)

    NASA Astrophysics Data System (ADS)

    Zesta, Eftyhia; Shi, Yong; Donovan, E.; Spanswick, E.; Lyons, Larry R.; Angelopoulos, V.; McFadden, J. P.; Carlson, C. W.; Auster, Hans-Ulrich; Mende, S.; McCready, M. A.; Heinselman, C. J.; Kendall, E.; Doe, R.

    2011-04-01

    Tail fast flows have been associated both with the onset of substorms and with auroral Poleward Boundary Intensifications (PBIs) that extend equatorward as streamers. We study here a series of bursts of fast tail flow that occurred on 5 March 2008 when four of the THEMIS probes were aligned in the tail from mid-tail to inner magnetosphere and were in good conjunction with the Sondrestrom Incoherent Scatter Radar. The series of burst are identified as two separate events. We find that the first event is associated with a small substorm onset, and the second with a PBI and then possibly another onset. The ionospheric flow signatures of the substorm and the PBI are distinctly different: the substorm onset is characterized by flow enhancement in the polar cap several minutes before onset and by sudden ionospheric flow reduction at onset, while the PBI is accompanied by a flow enhancement directed primarily equatorward and intruding from the polar cap into the plasma sheet.

  5. 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.

  6. Effects of large zonal plasma drifts on the subauroral ionosphere

    NASA Technical Reports Server (NTRS)

    Sellek, R.; Bailey, G. J.; Moffett, R. J.; Heelis, R. A.; Anderson, P. C.

    1991-01-01

    A model of the earth's ionosphere and plasmasphere is used to investigate the effects of an imposed westward plasma drift of maximum velocity 2 km/s. A closed subauroral tube of plasma is considered and the velocity spike persists for 10 min. Ion-neutral frictional heating causes rapid elevation of the F-region O(+) temperature. The F-layer O(+) concentration is decreased due to increased O(+) loss rate and rapid ion flows both upward and downward from the F-region. The upward flux of O(+) through the topside ionosphere can each 5 x 10 exp 9/sq cm/s; when the velocity spike ceases there is a return flow of O(+) that tends to replenish the F-layer. Most of the features revealed by the model for the F-region and topside ionosphere are in accord with observations of subauroral ion drifts. Downward flows that are predicted to be persistently present around the 300 km altitude level appear to agree with observations only occasionally; suggestions are made to resolve this discrepancy.

  7. Self-focusing instability in ionospheric plasma with thermal conduction

    SciTech Connect

    Sodha, Mahendra Singh; Sharma, Ashutosh; Verma, M. P.; Faisal, Mohammad

    2007-05-15

    In this communication, an expression for the growth rate of self-focusing instability in the ionospheric plasma has been derived after taking finite thermal conduction into account. The instability arises on account of the depletion of electrons from regions where the irradiance of the perturbation is large. In contrast to earlier work, an appropriate energy balance equation for electrons and ions and the proper dependence of thermal conductivity on electron temperature have been used. The dependence of the growth rate of the filamentation instability on the background irradiation, thermal conductivity, and the wave number of transverse perturbation has been investigated. The mid-latitude daytime ionospheric model of Gurevich has been used for numerical computations, corresponding to a height of 200 km. The gradient of irradiance perturbations is assumed to be along the magnetic field of the Earth. The numerical results have been illustrated graphically and discussed.

  8. 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.

  9. Modeling of Plasma Irregularities in Expanding Ionospheric Dust Clouds

    NASA Astrophysics Data System (ADS)

    Fu, H.; Scales, W.; Mahmoudian, A.; Bordikar, M. R.

    2009-12-01

    Natural dust layers occur in the earths mesosphere (50km-85km). Plasma irregularities are associated with these natural dust layers that produce radar echoes. Recently, an Ionospheric sounding rocket experiment was performed to investigate the plasma irregularities in upper atmospheric dust layers. The Charged Aerosol Release Experiment (CARE) uses a rocket payload injection of particles in the ionosphere to determine the mechanisms for enhanced radar scatter from plasma irregularities embedded in artificial dusty plasma in space. A 2-D hybrid computational model is described that may be used to study a variety of irregularities in dusty space plasmas which may lead to radar echoes. In this model, the dust and ions are both treated with Particle-In-Cell method while the dust charge varies with time based on the standard dust Orbit Motion Limited charging model. A stochastic model is adopted to remove particle ions due to the dust charging process. Electrons are treated with a fluid model including the parallel dynamics of magnetic fields. Fourier spectral methods with a predictor-corrector time advance are used to solve it. This numerical model will be used to investigate the electrodynamics and several possible plasma irregularity generation mechanisms after the creation of an artificial dust layer. The first is the dust ion-acoustic instability due to the drift of dust relative to the plasma. The instability saturates by trapping some ions. The effects of dust radius and dust drift velocity on plasma irregularities will be analyzed further. Also, a shear- driven instability in expanding dusty clouds is investigated.

  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. CUTLASS Finland radar observations of the ionospheric signatures of flux transfer events and the resulting plasma flows

    NASA Astrophysics Data System (ADS)

    Provan, G.; Yeoman, T. K.; Milan, S. E.

    1998-11-01

    The CUTLASS Finland radar has been run in a two-beam special scan mode, which offered excellent temporal and spatial information on the flows in the high-latitude ionosphere. A detailed study of one day of this data revealed a convection reversal boundary (CRB) in the CUTLASS field of view (f.o.v) on the dayside, the direction of plasma flow either side of the boundary being typical of a dawn-cell convection pattern. Poleward of the CRB a number of pulsed transients are observed, seemingly moving away from the radar. These transients are identified here as the ionospheric signature of flux transfer events (FTEs). Equatorward of the CRB continuous backscatter was observed, believed to be due to the return flow on closed field lines. The two-beam scan offered a new and innovative opportunity to determine the size and velocity of the ionospheric signatures associated with flux transfer events and the related plasma flow pattern. The transient signature was found to have an azimuthal extent of 1900 +/- 900 km and an poleward extent of sim250 km. The motion of the transient features was in a predominantly westward azimuthal direction, at a velocity of 7.5 +/- 3 km.

  13. Multistage substorm expansion: Auroral dynamics in relation to plasma sheet particle injection, precipitation, and plasma convection

    NASA Astrophysics Data System (ADS)

    Sandholt, Per Even; Farrugia, Charles J.; Lester, Mark; Cowley, Stan; Milan, Steve; Denig, William F.; Lybekk, BjRn; Trondsen, Espen; Vorobjev, Vjacheslav

    2002-11-01

    We present observations of the auroral expansions during two substorms, focusing on multistage intensifications and the morphology of the poleward boundary, and relate these auroral observations to the local plasma convection and plasma sheet dynamics. The observations are made by meridian scanning photometers and an all-sky camera (ASC) at Ny lesund, Svalbard (76 magnetic latitude (MLAT)), an ASC in Lovozero, Russia (64 MLAT), the International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer chain in Svalbard and Scandinavia, the HYDRA instrument on Polar located at the inner edge of the plasma sheet, particle detectors on DMSP F13 and DMSP F14 traversing the ionospheric projection of the plasma sheet, and the CUTLASS Finland HF radar. In each substorm the aurora between 70 and 80 MLAT consisted of two branches separated by 5 in MLAT. The higher-latitude branch (at 75-78MLAT) was subject to a sequence of short-lived (1-2 min) intensifications, so-called "poleward boundary intensifications" (PBIs), recurring at 3-min intervals. Subsequent to each brightening, auroral forms traveled equatorward at a speed of 1.0-1.5 km s-1. On Polar the PBIs are related on a one-to-one basis with injections of electrons in the 5- to 20-keV energy range at the inner edge of the equatorial plasma sheet with predominantly a trapped distribution, delayed by 5 min. Electron precipitation within 60-77 MLAT, corresponding to a large radial extent of the plasma sheet, is documented by DMSP flights in the 1800-2000 magnetic local time (MLT) sector. In discussing the branches of the high-latitude aurora within the context of current understanding of the relation of bursty bulk flows to substorm expansion phase dynamics, we note the following: (1) the initial auroral breakup located at 63-64 MLAT near the equatorward edge of plasma sheet precipitation, which was followed by (2) two successive brightenings/auroral expansions appearing within 72-74 MLAT/2100 MLT, separated by 14 min, (3) a 20-min-long brightening sequence in the poleward auroral branch (75-78 MLAT), consisting of six discrete events (PBIs) within the boundary plasma sheet precipitation, and (4) the presence of auroral vortex motion/strong field-aligned current sheets in some of these PBIs, which were accompanied by (5) electron injections at the inner edge of the plasma sheet, (6) brightenings of the lower-latitude auroral branch when equatorward moving auroral forms (EMAFs/streamers) arrive there, and (7) localized bursts of equatorward ionospheric convection at speeds of 0.5-1 km s-1 in the latitude range of the EMAFs/streamers. The documented associations between PBIs/EMAFs, plasma sheet injections, and the local convection events are explained in terms of a substorm scenario involving bursty bulk flows in the late expansion phase.

  14. 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.

  15. 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.

  16. Solar Wind Driven Plasma Fluxes from the Venus Ionosphere

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  17. Modulational excitation of inhomogeneities in dusty ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Kopnin, S. I.; Popel, S. I.; Morozova, T. I.

    2015-02-01

    The mechanism for the formation of inhomogeneities of the electron and ion densities in dusty ionospheric plasma as a result of the modulational instability of a pump electromagnetic wave caused by the excitation of dust acoustic perturbations is considered. The inhomogeneities of the electron density produced by the monochromatic radiation of heating facilities at altitudes of 80 and 100 km are estimated numerically. The possibility of excitation of relatively large inhomogeneities of the electron and ion densities ? n e( i)/ n e( i) ? 0.05 at altitudes of 80-100 km as a result of modulational interaction is demonstrated. The applicability domains of the method presented in this work are determined.

  18. 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.

  19. High-Latitude Plasma Convection from Cluster EDI Measurements: North-South Asymmetries

    NASA Astrophysics Data System (ADS)

    Haaland, S.; Foerster, M.; Paschmann, G.; Torbert, R. B.; Vaith, H.

    2009-12-01

    Recent observations have shown that the ionospheric response to processes in the magnetosphere can be very dissimilar in the northern and southern hemispheres. In this paper we present a statistical study of ionospheric convection patterns obtained from 7 years of electric field observations from the Cluster mission. The results show some prominent asymmetries between the two hemispheres, but most of the differences can probably be attributed to ionospheric conductivities. The results also demonstrate that magnetospheric convection is not simply the result of processes in the magnetospheric boundaries and the magnetotail, but that it is modified and partly controlled by ionospheric effects.

  20. Kinetic Space Weather: Toward a Global Hybrid Model of the Polar Ionosphere-Lower Magnetosphere Plasma Transport

    NASA Technical Reports Server (NTRS)

    Horwitz, James L.

    1996-01-01

    During the indicated period of performance, we had a number of publications concerned with kinetic polar ionosphere-lower magnetosphere plasma transport. For the IUGG 1991-4 Quadrennial Report, we reviewed aspects of U.S. accomplishments concerned with polar plasma transport, among other issues. In another review, we examined the computer simulations of multiple-scale processes in space plasmas, including polar plasma outflow and transport. We also examined specifically multiscale processes in ionospheric outflows. We developed a Generalized Semi-Kinetic(GSK) model for the topside-lower magnetosphere which explored the synergistic action of wave heating and electric potentials in the formation of auroral Ion conics, in particular the "pressure cooker" mechanism. We extended the GSK model all the way down to 120 km and applied this code to illustrate the response of the ionosphere- magnetosphere to soft-electron precipitation and convection-driven frictional ion heating, respectively. Later, the convection-driven heating work was extended to a paper for the Journal of Geophysical Research. In addition to the above full published papers, we also presented the first developments of the coupled fluid-semikinetic model for polar plasma transport during this period. The results from a steady-state treatment were presented, with the second presentation being concerned with the effects of photo-electrons on the polar wind, and the first garnering an outstanding student paper award from the American Geophysical Union. We presented the first results from a time-dependent version of this coupled fluid-semikinetic model.

  1. 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.

  2. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  4. Interhemispheric differences and solar cycle effects of the high-latitude ionospheric convection patterns deduced from Cluster EDI observations

    NASA Astrophysics Data System (ADS)

    Frster, Matthias; Haaland, Stein

    2015-04-01

    Here, we present a study of ionospheric convection at high latitudes that is based on satellite measurements of the Electron Drift Instrument (EDI) on-board the Cluster satellites, which were obtained over a full solar cycle (2001-2013). The mapped drift measurements are covering both hemispheres and a variety of different solar wind and interplanetary magnetic field (IMF) conditions. The large amount of data allows us to perform more detailed statistical studies. We show that flow patterns and polar cap potentials can differ between the two hemispheres on statistical average for a given IMF orientation. In particular, during southward directed IMF conditions, and thus enhanced energy input from the solar wind, we find that the southern polar cap has a higher cross polar cap potential. We also find persistent north-south asymmetries which cannot be explained by external drivers alone. Much of these asymmetries can probably be explained by significant differences in the strength and configuration of the geomagnetic field between the Northern and Southern Hemisphere. Since the ionosphere is magnetically connected to the magnetosphere, this difference will also be reflected in the magnetosphere in the form of different feedback from the two hemispheres. Consequently, local ionospheric conditions and the geomagnetic field configuration are important for north-south asymmetries in large regions of geospace. The average convection is higher during periods with high solar activity. Although local ionospheric conditions may play a role, we mainly attribute this to higher geomagnetic activity due to enhanced solar wind - magnetosphere interactions.

  5. 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.

  6. Plasma turbulence in the equatorial ionospheric F region

    NASA Astrophysics Data System (ADS)

    McDaniel, Rickey Dale

    Equatorial spread F is a spectacular phenomenon in which the equatorial region ionosphere is reshaped after sunset. The plasma instabilities responsible for equatorial spread F are fascinating since they occur on time scales ranging from seconds to hours and length scales from centimeters to tens of kilometers. The plasma irregularities that occur in the F region also influence the performance and reliability of space borne and ground based electronic systems and may cause the disruption of satellite operations, communications, navigation, and electrical power distribution grids, leading to potentially broad economic losses. The ionospheric model equations that describe these plasma instabilities display different dynamical behavior based on the value of the ion-neutral collision frequency. The transition occurs at the so-called inertial regime of the ionosphere, where the model equations are similar to the Navier Stokes equations except applied to inhomogeneous fluids. A general analytic solution does not exist for these nonlinear equations; however, a numerical model is developed by maintaining charge neutrality in the vicinity of a circular bubble rising from the collisional to the inertial regime. Using this model, we are able to determine the location of the inertial regime as a function of local time, longitude, season, and solar cycle. The model results determine that the regime occurs generally from about 2000 and 2100 local time and 500-900 km apex height. Also, the model predicts that solar minimum periods are generally more conducive for inertial effects than solar maximum periods. Time series analysis performed on Dynamics Explorer II ion density data show that a turbulent cascade form in the inertial regime predicted by the model. Intermediate scale density power spectra all obey k-5/3 spectra scaling when measured in altitude and local time windows predicted by our model as failing within the inertial regime. Meanwhile, density power spectra for data lying outside the inertial regime take on a range of power laws between k-0.75 and k-2.2 . Applying a wavelet transform, we are able to show that large depletions are necessary for inertial regime flows to exist.

  7. 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.

  8. 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.

  9. 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.

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

    SciTech Connect

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

    1983-03-01

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

  11. High-latitude plasma convection from Cluster EDI measurements: method and IMF-dependence

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

    We have used vector measurements of the electron drift velocity made by the Electron Drift Instrument (EDI) on Cluster between February 2001 and March 2006 to derive statistical maps of the high-latitude plasma convection. The EDI measurements, obtained at geocentric distances between ~4 and ~20 RE over both hemispheres, are mapped into the polar ionosphere, and sorted according to the clock-angle of the interplanetary magnetic field (IMF), measured at ACE and propagated to Earth, using best estimates of the orientation of the IMF variations. Only intervals of stable IMF are used, based on the magnitude of a "bias-vector" constructed from 30-min averages. The resulting data set consists of a total of 5862 h of EDI data. Contour maps of the electric potential in the polar ionosphere are subsequently derived from the mapped and averaged ionospheric drift vectors. Comparison with published statistical results based on Super Dual Auroral Radar Network (SuperDARN) radar and low-altitude satellite measurements shows excellent agreement between the average convection patterns, and in particular the lack of mirror-symmetry between the effects of positive and negative IMF By, the appearance of a duskward flow component for strongly southward IMF, and the general weakening of the average flows and potentials for northerly IMF directions. This agreement lends credence to the validity of the assumption underlying the mapping of the EDI data, namely that magnetic field lines are equipotentials. For strongly northward IMF the mapped EDI data show the clear emergence of two counter-rotating lobe cells with a channel of sunward flow between them. The total potential drops across the polar caps obtained from the mapped EDI data are intermediate between the radar and the low-altitude satellite results.

  12. 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.

  13. Dependence of the ionospheric convection pattern on the conductivity and the southward IMF. Ph.D. Thesis

    SciTech Connect

    Shue, J.

    1993-12-31

    Electric field measurements from the DE-2 satellite were used to determine the location of the convection reversal boundary and the potential around this boundary under a combination of interplanetary magnetic field (IMF) and auroral electrojet conditions. The electric potential is obtained by the integration of the electric fields. The convection reversal boundary is defined in this study as where the potential has its absolute maximum and minimum values. The data were sorted into 18 categories according to two levels of the negative IMF B(sub z), three ranges of IMF B(sub y), and two substorm phases. The data were fit with both continuous and discontinuous boundaries to get a functional representation of boundary potentials and locations. A simple model is constructed by solving Laplace`s equation in order to illustrate the obtained boundary potentials and locations. The results show that the enhanced electric field in the midnight sector is associated with an intense westward electrojet current. It can also be seen that the convection reversal boundary is found to be discontinuous near midnight. The discontinuous convection reversal boundary on the dayside is related to the merging near dayside cusp region. The discontinuous convection reversal boundary on the nightside is related to the conductivity enhancement. The intrusion of the dawn cell into the dusk cell is due to nonuniformity of the Hall conductivity in the ionosphere. Another model is constructed by solving the current continuity equation with field-aligned current and nonuniform conductivity added. It can be found that a secondary convection reversal, which is detached from the dusk-cell convection reversal, appears in the evening-midnight sector within the polar cap when the IMF B(sub y) is positive and the conductivity is nonuniform. This convection reversal is attributed to the B x V dynamo.

  14. 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.

  15. Divergent subcritical convection in magnetized plasma from asymmetric sourcing

    SciTech Connect

    Adler, D.T.; Hassam, A.B.

    2005-06-15

    Asymmetric particle and heat sourcing in a plasma confined in a closed magnetic field line configuration results in convection cells, as is well known. This phenomenon occurs even if the sourcing on average produces density and temperature profiles that are subcritical, i.e., magnetohydrodynamically stable to interchange modes. Such subcritical convection is expected to be small compared to the convection from supercritical driving for which the system is interchange unstable. The ratio of subcritical to supercritical convection is expected to scale as the inverse Reynolds numbers (for large Reynolds numbers). It is shown that this ratio is, in fact, considerably larger. As marginal stability is approached, the subcritical convection grows from very small to almost the unstable convection size, i.e., of order unity. This effect may be similar to why a driven, damped harmonic oscillator increases in amplitude as resonance is approached. A numerical simulation is done to demonstrate this effect. It is also shown that transport from the large convection can be substantial.

  16. Transequatorial F-region ionospheric plasma bubbles: solar cycle effects

    NASA Astrophysics Data System (ADS)

    Sahai, Y.; Fagundes, P. R.; Bittencourt, J. A.

    2000-10-01

    During the recent past, wide-angle optical imaging observations of F-region nightglow emissions (e.g. OI 630nm) have provided excellent results related to the occurrence, evolution and dynamics of strong large-scale range spread-F irregularities, as they are characterized by large-scale ionospheric plasma depletions, generally known as transequatorial plasma bubbles, which result in quasi north-south aligned intensity depleted bands. The intensity depletions seen in the airglow images are the optical signature, at the height range of the emitting layer of transequatorial magnetic field-aligned plasma bubbles. An all-sky imaging system, observing the OI 630nm emission, was operational at Cachoeira Paulista (/22.7S, /45.0W /~16S dip latitude), Brazil, during the period March 1987 to October 1991. It was put back in operation again in September 1994 and observations are continuing. These observations have provided an extensive data-base of OI 630 nm images which permitted us to address several aspects related to the formation and development of large-scale spread-F plasma irregularities during both high- and low solar activity periods. An analysis of about 11,000 images from these investigations are presented and discussed in this paper. The seasonal occurrence characteristics are fairly similar for both low and high solar activities. However, the occurrences of intensity depleted bands are much less during low solar activity (33%) as compared with high solar activity (55%). Also, some of the intensity depleted bands in the images (which show the optical signatures at the height of the emitting layer around 250-300 km) indicating that plasma bubbles attaining very high altitudes (>1500km) at the magnetic equator (by mapping the depletion bands along geomagnetic field lines to the equatorial plane (e.g., Mendillo, Tyler, J. Geophys. Res. 88 (1983) 5758), are much less during low solar activity (34% of the images with intensity depleted bands) as compared with high solar activity (66% of the images with intensity depleted bands). The average nocturnal variations of intensity depleted regions show different characteristics during the high and low solar activity periods.

  17. Electrostatic plasma turbulence in the topside equatorial F region ionosphere

    NASA Astrophysics Data System (ADS)

    Hysell, D. L.; Shume, E. B.

    2002-10-01

    Two-dimensional, turbulent plasma flows in the topside equatorial F region ionosphere associated with fully developed equatorial spread F are analyzed and simulated numerically. In the inertially dominated flow regime, the governing equations of motion resemble the Navier Stokes equation but are cubicly nonlinear. Large amplitude density irregularities are prerequisite for inertial effects to be important, but when these are present, the third-order nonlinear effects become significant, mean-squared velocity and vorticity cease to be conserved by nonlinear mode coupling, and the foundations of the turbulent cascade theory of [1967] are undermined. Nonetheless, one-dimensional, angle-averaged velocity spectra computed from simulated flows exhibit similarity ranges with k-5/3 and k-3 power laws, resembling inertial ranges and suggesting turbulent cascades. Invariants of the flow (quantities conserved by nonlinear mode coupling) are found which are generalizations of the quadratic forms of kinetic energy and enstrophy and which are dimensionally equivalent to them. Statistical properties of the flow appear to permit turbulent cascades to arise.

  18. 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.

  19. Ionospheric perturbations in plasma parameters before global strong earthquakes

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Huang, Jianping; Zhang, Xuemin

    2014-03-01

    Based on the electron density (Ne) and temperature (Te) data from DEMETER, the ionospheric perturbations before 82 Ms ? 7.0 earthquakes (EQs) during 2005-2010 were studied, using moving median and space difference methods within 10 days before and 2 days after these events in local nighttime. It was found that the plasma parameters disturbances appeared before 49 EQs, in which more disturbances were detected before shallow-focus earthquakes than deep ones, and there was little difference between continental and oceanic ones, both exceeding 1/2 percentage. For the disturbed time, more perturbations were seen in 1, 3, 5, 6, 8 days before EQs and 1 day after EQs. For the spatial distribution, the anomalies before EQs were not just above the epicenters, but shifted equatorward with several degrees to almost twenty degrees. Most of the abnormities were positive ones, which demonstrate that Ne increases before EQs at the altitude of 670 km of DEMETER. Perturbations of Ne were more than that of Te, which illustrates that Ne is much more sensitive to seismic activity than Te.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. The Role of the Ionosphere in Providing Plasma to the Terrestrial MagnetosphereAn 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Propagation of Impulse-Like Waveforms Through the Ionosphere Modeled by Cold Plasma

    NASA Astrophysics Data System (ADS)

    Giri, D. V.; Dvorak, S. L.

    In this chapter, we have studied the propagation of short, impulse-like pulses propagating through the ionosphere. The ionosphere is modeled by simple, cold plasma. The impulse response of such a plasma model is known to consist of two terms. The first term is the impulse itself and the second term contains a Bessel function of first order. This means that the impulse propagates as an impulse followed by a long, oscillatory tail. The numerical example studied here is that of the prototype impulse radiating antenna (IRA). Closed-form expressions are developed for the prototype IRA waveform propagation through the cold-plasma model of the ionosphere. The results are cross-checked with numerical evaluation via a convolution process that uses the known impulse response.

  12. 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).

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    1981-01-01

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

  17. 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

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

    NASA Astrophysics Data System (ADS)

    Mendillo, M.; Baumgardner, J.; Allen, D. P.; Foster, J.; Holt, J.

    1987-11-01

    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, releasing large amounts of exhaust molecules 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 to 2 deg 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.

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

    NASA Astrophysics Data System (ADS)

    Amm, O.; Vanhamki, 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.

  20. 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.

  1. Numerical simulation of the plasma thermal disturbances during ionospheric modification experiments at the SURA heating facility

    NASA Astrophysics Data System (ADS)

    Belov, Alexey; Huba, J. D.

    indent=1cm We present the results of numerical simulation of the near-Earth plasma disturbances produced by resonant heating of the ionospheric F-region by high-power HF radio emission from the SURA facility. The computational model is based on the modified version of the SAMI2 code (release 1.00). The model input parameters are appropriated to the conditions of the SURA-DEMETER experiment. In this work, we study the spatial structure and temporal characteristics of stimulated large-scale disturbances of the electron number density and temperature. It is shown that the stimulated disturbances are observed throughout the ionosphere. Disturbances are recorded both in the region below the pump wave reflection level and in the outer ionosphere (up to 3000 km). At the DEMETER altitude, an increase in the ion number density is stipulated by the oxygen ions O (+) , whereas the number density of lighter H (+) ions decreases. A typical time of the formation of large-scale plasma density disturbances in the outer ionosphere is 2-3 min. After the heater is turned off, the disturbances relaxation time is approximately 30 min. The simulation results are important for planning future promising experiments on the formation of ionospheric artificial density ducts. This work was supported by the Russian Foundation for Basic Research (project No. 12-02-00747-a), and the Government of the Russian Federation (contract No. 14.B25.31.0008).

  2. 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.

  3. 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.

  4. Kinetic modeling of O(+) upflows resulting from E x B convection heating in the high-latitude F region ionosphere

    NASA Technical Reports Server (NTRS)

    Wilson, G. R.

    1994-01-01

    We report here the results of modeling work aimed at understanding the development of ionospheric O(+) field-aligned upflows that develop in response to high-latitude E x B drift induced frictional heating. The model used is a collisional semikinetic model which includes ion-neutral resonant charge exchange and polarization collisions as well as Coulomb self-collisions. It also includes the process of chemical removal of O(+) as well as all of the macroscopic forces: ambipolar electric, gravity, magnetic mirror, and centripetal. Model results show the development of several types of non-Maxwellian velocity distributions including toroids at low altitude, distributions with large heat flow in the perpendicular component at intermediate altitudes, and distributions with a separate upflowing population or upward superthermal tail at high altitudes. Whenever the convection electric field increases from a small value (less than 25 mV/m) to a large value (100-200 mV/m) in 6 min or less large upflows develop with parallel drift speeds which peak (below 1000 km) at values between 500 m/s and 2 km/s, parallel fluxes which peak between 6.0 x 10(exp 8) and 3.2 x 10(exp 9)/sq cm/s, and parallel per particle heat flows which peak between 8.0 x 10(exp -9) and 8.0 x 10(exp -8) ergs cm/s. The higher values in these ranges occur for a cooler neutral atmosphere, with a larger convection electric field that is turned on quickly. The model produces field-aligned O(+) flow speeds that are larger than those produced by a 20-moment generalized transport model but smaller then those produced by an isotropic hydrodynamic model for comparable values of the convection turn on times. The model results compare favorably with some topside satellite and radar data.

  5. A model of ionospheric image structure underneath a braking, cross-field plasma jet

    NASA Technical Reports Server (NTRS)

    Jacobson, Abram R.; Simons, David J.; Nalesso, Gianfranco

    1987-01-01

    A plasma jetting across the geomagnetic field above the ionosphere tends to brake by ohmic dissipation of Pedersen currents. The braking can affect the ionosphere underneath if the associated Pedersen drifts are intense and prolonged enough to cause cumulative image structuring. Here, such image structuring is studied for the parameter regime of forthcoming releases from the Combined Release and Radiation Effects Satellite, involving photoionization of kilograms of barium vapor moving at orbital velocity. The resultant structuring in the upper E-region offers possible diagnostic telltales of the braking process.

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

    NASA Astrophysics Data System (ADS)

    Sittler, E. C., Jr.; Hartle, R. E.; Ali, A.; Cooper, J. F.; Lipatov, A. S.; Simpson, D. G.; Sarantos, M.; Chornay, D. J.

    2014-12-01

    In [1] the first quantitative evidence of ionospheric outflows (r > 10,000 km) coming from Titan was given using the Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS) data for the T9 flyby. Later in [2] similar outflows were shown for T63 and T75. In [3] evidence for ionospheric outflows for T15 was given and [4] showed evidence of outflows for T41. Normally, the CAPS IMS cannot be used to measure Titan's relatively dense ionosphere because the IMS has high sensitivity to measure the more tenuous plasmas of Saturn's magnetosphere and its detectors will experience count rates beyond their maximum allowed rates, therefore the IMS is configured not to measure the ionospheric plasma. But, whenever there are high altitude Titan wake flybys the ion densities are low enough so the CAPS IMS can measure these ionospheric outflows and their corresponding composition characteristic of the topside ionosphere (i.e., composition freezes in above the exobase) using its unique compositional capabilities. For example, the IMS can distinguish against specific ion types such as hydrocarbon, nitrile and water group ions due fragmentation of molecular ions within the instrument (i.e., incident ions strikes ultra-thin carbon foils at 14.6 kV or higher with exiting fragments such C+,0,-, N+,0, O+,0,-1). The other ionospheric instruments only measure the ion mass-per-charge (M/Q), while the CAPS IMS measures both the ion M/Q and its fragments. Specific attention will be given to such ions as NH4+, N+, O+, CH4+, C2H5+, HCNH+ and C3H7+. These results may impose important constraints upon Titan's ionospheric water group, hydrocarbon and nitrile ion chemistry. Are NH4+ ions present as indicated by INMS at 1100 km altitude and/or water group ions? Our work has concentrated on the T15 flyby. Estimates of the NH4+, N+ and O+ abundances presently have upper values < 20% of the total ion density with actual abundances and their uncertainties to be given. [1] Sittler, E.C. Jr., et al., (2010), Planet. Space Sci., 58, 327-350. [2] Coates, A.J., et al., (2012), J. Geophys. Res., 117, A05324, doi:10.1029/2012JA017595. [3] Sillanp et al., (2011), J. Geophys. Res., 116, A07223, doi:10.1029/2011JA016443. [4] Sittler, E. C., Jr., et al., (2013), Fall AGU Abstract P53C-1880, San Francisco, CA.

  7. 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 Alfvn 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 Alfvn 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Lunar atmospheric tidal effects in the plasma drifts observed by the Low-Latitude Ionospheric Sensor Network

    NASA Astrophysics Data System (ADS)

    Eccles, Vince; Rice, Donald D.; Sojka, Jan J.; Valladares, Cesar E.; Bullett, Terence; Chau, Jorge L.

    2011-07-01

    Data from the Low-Latitude Ionospheric Sensor Network are used to examine ionospheric electrodynamics during quiet, low solar conditions from September to November 2009. The ground-based magnetometers and the Jicamarca Vertical Incidence Pulsed Ionospheric Radar ionosonde in the Peruvian Sector are used to identify the neutral winds and plasma drifts that control the large-scale plasma structure of the ionosphere. It is observed that the solar- and lunar-driven semidiurnal tides have a significant influence on the background electrodynamics during this period of extreme solar minimum. The lunar tidal influence of the ionosphere electrodynamics is a large component of the variation of the vertical drift during the geophysically quiet study period. A significant portion, though not all, of the variation through the lunar month can be attributed to the lunar semidiurnal tide.

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

    NASA Technical Reports Server (NTRS)

    Kozlovsky, A.; Koustov, A.; Lyatsky, W.; Kangas, J.; Parks, G.; Chua, D.

    2002-01-01

    Super Dual Auroral Radar Network (SuperDARN) observations, ultraviolet imaging from the Polar satellite (UVI), and particle precipitation data from DMSP satellites have been used to investigate the electrodynamics of the postnoon auroral oval in the Northern hemisphere. We show that: (1) For negative IMF By, the convection reversal (CR) was co-located with the maximum of auroral luminosity, but during positive IMF By the convection reversal was poleward of the auroral oval up to several degrees in latitude; (2) Postnoon auroral oval was associated with a large-scale upward field-aligned current (FAC) of the order of 6x10(exp -7). A m(exp -2) in magnitude (the FAC was inferred from the SuperDARN and UVI data). For negative IMF By, maximum of the auroral intensity coincides in latitude with the maximum of the upward field-aligned current. However, for positive IMF By. the maximum of the upward FAC was shifted to the poleward edge of the auroral oval; (3) In response to the IMF By turning from positive to negative, the maximum of the auroral luminosity did not change its position noticeably, but the position of the convection reversal changed considerably from 80-81 degs to about 76 degs MLAT, and the maximum of FAC moved from 77-78 degs to about 76 degs MLAT. Thus, after IMF By turns negative, both the FAC maximum and CR tend to coincide with the auroral maximum; (4) The IMF Bz positive deflection was followed by a decrease in both field-aligned current intensity and auroral luminosity. However, the decrease in the auroral luminosity lags behind the FAC decrease by about 12 min. Firstly, these observations allow us to suggest that the IMF By-related electric field can penetrate into the closed magnetosphere and produce convection and FAC changes in the region of the postnoon auroral oval. Secondly, we suggest that the interchange instability is a promising mechanism for the postnoon auroras.

  17. Plasma waves observed at low altitudes in the tenuous Venus nightside ionosphere

    NASA Technical Reports Server (NTRS)

    Strangeway, R. J.; Russell, C. T.; Ho, C. M.; Brace, L. H.

    1993-01-01

    The Pioneer Venus (PV) Orbiter Electric Field Detector (OEFD) measured many plasma wave bursts throughout the low altitude ionosphere during the final entry phase of the spacecraft. Apart from 100 Hz bursts observed at very low altitudes (approx. 130 km), the bursts fall into two classes. The first of these is a wideband signal that is observed in regions of low magnetic field, but average densities, in comparison to the prevailing ionospheric condition. This wideband signal is not observed in the 30 kHz channel of the OEFD, but is resricted to the 5.4 kHz channel and lower. Since these bursts are observed with roughly constant burst rate above 160 km altitude, we attribute them to ion acoustic mode waves generated by precipitating solar wind electrons. The second type of signal is restricted to 100 Hz only, and is observed in the regions of low electron beta, consistent with whistler-mode waves. These waves could be generated by lightning in the Venus atmosphere if the vertical component of the magnetic field greater than 3.6 nT. Because the ionosphere is very different during the entry phase, compared to the ionosphere as observed early in the Pioneer Venus mission, any conclusions regarding the source of the plasma waves detected during entry phase cannot be applied directly to the earlier observations.

  18. A case study on ionospheric scintillations at low latitude associated with a plasma blob observed in situ

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Shi, J. K.; Torkar, K.; Wang, G. J.; Wang, X.

    2015-04-01

    In general, ionospheric scintillations at low latitude are considered as signatures of equatorial plasma bubbles (depletions). However, some authors considered that scintillations may also be associated with plasma blobs (enhancements), but there was no in situ measurement hitherto to confirm it. We performed a case study on the concurrent observation of an ionospheric plasma blob with in situ measurements by ROCSAT-1 (i.e. Formosa satellite-1) and of GPS amplitude scintillations in the low-latitude ionosphere on 1 June 2003. The blob measured in situ had a scale size of about 800 km in the F layer, and the ion density inside the blob was severely disturbed. Amplitude scintillation with S4 > 0.3 was observed concurrently in the same longitude range as the blob measured. This case study provides evidence of simultaneously observed GPS amplitude scintillations and a blob in situ, and it confirms that scintillations can be associated with plasma blobs in the low-latitude ionosphere.

  19. 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.

  20. 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.

  1. Response of High Latitude Birkeland Currents and Ionospheric Convection to Transitions in Solar Wind Forcing

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Korth, H.; Merkin, V. G.; Barnes, R. J.; Ruohoniemi, J. M.

    2014-12-01

    Recent results from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) indicate that at least some transitions from northward to southward IMF produce a specific sequence in the development of large-scale Birkeland currents. First, a set of Region 1 and Region 2 currents forms on the dayside restricted to within a few hours of noon. After about 40 minutes, currents strongly intensify on the nightside, first near midnight local time associated with substorm onset, and then progressively further toward the dayside via dawn and dusk. Only after an hour or more after the transition to stronger solar wind forcing, is the complete Region 1, Region 2 current system developed. The results imply that the initial response to a transition from weak to strong forcing is convection into the polar cap and lobes without strong return convection to the dayside from the nightside magnetosphere. Return convection from the nightside begins with substorm onset and progresses to the dayside. This analysis is extended by examining a large number of transitions from prolonged auroral quiescence, associated with northward IMF, to southward IMF and the development of large-scale Region 1/Region 2 Birkeland currents, to assess whether the above progression holds in general. In addition, transition events to particularly intense driving, for example, associated with shocks are examined to assess how this ordering of events may be changed for onsets of particularly intense solar wind forcing.

  2. 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

    NASA Astrophysics Data System (ADS)

    Secan, James A.

    1985-04-01

    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 Center 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 parameterization 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 O(+) 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.

  3. Real-time tracking and targeting computations and rocket vehicle aeroballistics for the PLACES ionospheric plasma test series

    NASA Astrophysics Data System (ADS)

    Rollstin, L. R.

    The PLACES (Position Location And Communication Effects Simulations) test program, conducted in December 1980 at Eglin Gulf Test Range, involved a series of ionospheric releases of barium/barium-nitrate vapor. The Defense Nuclear Agency sponsored program investigated effects of a structured ionospheric plasma (similar to that produced by a high-altitude nuclear explosion) on satellite navigation systems and provided in situ measurement of plasma structure. Terrier-Tomahawk rocket systems boosted the barium payloads, beacon payloads (plasma occultation experiment), and probe payloads (plasma in situ measurement). Drifting plasma tracking procedures, beacon- and probe-vehicle targeting procedures, and vehicle flight test results are presented.

  4. 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.

  5. Atmosphere-Ionosphere Electrodynamic Coupling

    NASA Astrophysics Data System (ADS)

    Sorokin, V. M.; Chmyrev, V. M.

    Numerous phenomena that occur in the mesosphere, ionosphere, and the magnetosphere of the Earth are caused by the sources located in the lower atmosphere and on the ground. We describe the effects produced by lightning activity and by ground-based transmitters operated in high frequency (HF) and very low frequency (VLF) ranges. Among these phenomena are the ionosphere heating and the formation of plasma density inhomogeneities, the excitation of gamma ray bursts and atmospheric emissions in different spectral bands, the generation of ULF/ELF/VLF electromagnetic waves and plasma turbulence in the ionosphere, the stimulation of radiation belt electron precipitations and the acceleration of ions in the upper ionosphere. The most interesting results of experimental and theoretical studies of these phenomena are discussed below. The ionosphere is subject to the action of the conductive electric current flowing in the atmosphere-ionosphere circuit. We present a physical model of DC electric field and current formation in this circuit. The key element of this model is an external current, which is formed with the occurrence of convective upward transport of charged aerosols and their gravitational sedimentation in the atmosphere. An increase in the level of atmospheric radioactivity results in the appearance of additional ionization and change of electrical conductivity. Variation of conductivity and external current in the lower atmosphere leads to perturbation of the electric current flowing in the global atmosphere-ionosphere circuit and to the associated DC electric field perturbation both on the Earth's surface and in the ionosphere. Description of these processes and some results of the electric field and current calculations are presented below. The seismic-induced electric field perturbations produce noticeable effects in the ionosphere by generating the electromagnetic field and plasma disturbances. We describe the generation mechanisms of such experimentally observed effects as excitation of plasma density inhomogeneities, field-aligned currents, and ULF/ELF emissions and the modification of electron and ion altitude profiles in the upper ionosphere. The electrodynamic model of the ionosphere modification under the influence of some natural and man-made processes in the atmosphere is also discussed. The model is based on the satellite and ground measurements of electromagnetic field and plasma perturbations and on the data on atmospheric radioactivity and soil gas injection into the atmosphere.

  6. 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

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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.

  9. Plasma inhomogeneities and radiowave scattering in experiments with electron pulses in the ionosphere

    NASA Astrophysics Data System (ADS)

    Izhovkina, N. I.; Erokhin, N. S.; Mikhailovskaya, L. A.

    2014-01-01

    The absorption of telemetry radiosignals at frequencies of 250 and 75 MHz, transmitted from rockets, was observed in the ARAKS and Zarnitza 2 rocket experiments, respectively, with electron pulses in the ionosphere. The signals were registered with ground receivers. Four cases of complete signal absorption on the propagation path were observed in the ARAKS experiment. The radio absorption at frequencies substantially higher than the plasma and upper hybrid frequencies can be related to wave scattering by plasma inhomogeneities. It has been indicated that plasma inhomogeneities were generated when electrostatic oscillations damped in the region with decreased plasma density at a decrease in the natural oscillation phase volume in the frequency-wave vector space with decreasing plasma density. The observed radio absorption could be related to reflectionless wave scattering in an inhomogeneous plasma structure.

  10. 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.

  11. Mid-latitude ionospheric perturbation associated with the Spacelab-2 plasma depletion experiment at Millstone Hill

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Holt, J. M.; Lanzerotti, L. J.

    2000-01-01

    Elevation scans across geomagnetic mid latitudes by the incoherent scatter radar at Millstone Hill captured the ionospheric response to the firing of the Space Shuttle Challenger OMS thrusters near the peak of the F layer on July 30, 1985. Details of the excitation of airglow and the formation of an ionospheric hole during this event have been reported in an earlier paper by Mendillo et al.. The depletion (factor sim2) near the 320 km Shuttle orbital altitude persisted for sim35 min and then recovered to near normal levels, while at 265 km the density was reduced by a factor of sim6; this significant reduction in the bottomside F-region density persisted for more than 3 hours. Total electron content in the vicinity of the hole was reduced by more than a factor of 2, and an oscillation of the F-region densities with 40-min period ensued and persisted for several hours. Plasma vertical Doppler velocity varied quasi-periodically with a sim80-min period, while magnetic field variations observed on the field line through the Shuttle-burn position exhibited a similar sim80-min periodicity. An interval of magnetic field variations at hydromagnetic frequencies (sim95 s period) accompanied the ionospheric perturbations on this field line. Radar observations revealed a downward phase progression of the 40-min period density enhancements of -1.12 km-1, corresponding to a 320-km vertical wavelength. An auroral-latitude geomagnetic disturbance began near the time of the Spacelab-2 experiment and was associated with the imposition of a strong southward IMF Bz across the magnetosphere. This created an additional complication in the interpretation of the active ionospheric experiment. It cannot be determined uniquely whether the ionospheric oscillations, which followed the Spacelab-2 experiment, were related to the active experiment or were the result of a propagating ionospheric disturbance (TID) launched by the enhanced auroral activity. The most reasonable conclusion is that the ionospheric oscillations were a result of the coincident geomagnetic disturbance. The pronounced depletion of the bottomside ionosphere, however, accentuated the oscillatory behavior during the interval following the Shuttle OMS burn.

  12. Understanding Substorms from the Auroral Ionosphere to the Distant Plasma Sheet

    NASA Technical Reports Server (NTRS)

    Parks, G. K.; Brittnacher, M.; Chen, L.; Chua, D.; Elsen, R.; Fillingim, M.; McCarthy, M.; Wilber, M.; Germany, G.; Spann, J.; Lin, R. P.

    1998-01-01

    The global polar UVI images have been correlated with observations from the ground, ionosphere, geomagnetic tail between 10-20 earth radii and the interplanetary space. One of the objectives of our study is to better understand the connection among many complex phenomena occurring close to Earth and those in the near--earth plasma sheet. We have examined the details of how the auroral and polar cap boundaries at different local times behave in relation to variations occurring in the solar wind, ionosphere and plasma sheet during substorms. We have also compared locations of boundaries deduced from images to electron flux "boundaries" observed by polar orbiting spacecraft. Our results indicate that the ionospheric dynamics is important and polar cap and auroral oval boundaries expand and contract in a complicated but systematic way. These variations are correlated to solar wind parameters and growth and recovery phenomena in the plasma sheet. These results can be interpreted in terms of directly driven and/or unloading substorm processes.

  13. 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.

  14. 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.

  15. 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.

  16. Source mechanisms and radio effects of ionospheric plasma. Annual report, 1 October 1991-30 September 1992

    SciTech Connect

    Lee, M.C.

    1992-11-01

    Since October 1, 1991 experimental and theoretical research has been conducted by Prof. Min-Chang Lee and his students at BU and MIT. This research work is aimed at investigating the ionospheric plasma disturbances which can affect significantly the radio wave propagation in communications and space surveillance. The research topics which have been investigated include: (1) A source mechanism leading to the symmetric lower hybrid sidebands and a low-frequency mode in the upper atmosphere, (2) Characteristics of lightning-induced plasmas, (3) Radio wave-produced plasmas and effects on radio communications, (4) Plasma turbulence and formation of field aligned density fluctuations as ionospheric ducts.

  17. Spatial and Temporal Response of Auroral and Subauroral Plasma Convection to High- Latitude Drivers of Geomagnetic Activity

    NASA Astrophysics Data System (ADS)

    Greenwald, R. A.; Ruohoniemi, M.; Baker, J. B.; Talaat, E.; Lester, M.; Oksavik, K.

    2008-12-01

    During the IPY, the second of two lower-latitude SuperDARN radars was put into operation in the eastern U.S. Located at Blackstone, VA and directed toward central Canada, it extends the coverage of the preexisting Wallops Island radar to more than 4 hours of magnetic local time and covers 50-70 degrees geomagnetic latitude providing coverage of ionospheric plasma convection and electric fields on magnetic field lines connected to the inner boundary of the plasmasheet, ring current and plasmapause. Although initial measurements with this coordinated pair of radars were made at a time of low geomagnetic activity, there have been many opportunities to examine both the spatial and temporal response of low-latitude auroral and subauroral plasma convection and its associated electric field to a variety of high-latitude magnetospheric drivers including dayside reconnection and midnight sector substorms. In this paper, we discuss the dynamical response of these flows to both dayside reconnection and substorms. We specifically examine the timing, location, spatial extent and intensity of these flow enhancements versus the nature and strength of the driver.

  18. Comparative studies of the plasma turbulence in the different regions of the ionosphere- discussion of the results from DEMETER satellite

    NASA Astrophysics Data System (ADS)

    Blecki, J.; Ko?ciesza, M.; Boudjada, M.; Parrot, M.; Savin, S.; Wronowski, R.

    2012-04-01

    Plasma turbulence is a very common phenomenon in the Earth's ionosphere. There are difference sources of it, but the generally the nonlinear developing of the plasma instabilities is a main cause of its presence. In the ionosphere there are several regions with conditions favorable for the generation and developing of the plasma instabilities. The main regions in which the turbulence has been registered are: equatorial ionosphere, auroral oval, polar cusp, ionospheric trough and also regions over epicenters of the earthquakes. The turbulence is characterized as multiscale nonlinear and intermittent process. We will present results of electric field wave form analysis using wavelet and bispectral methods for selected strong earthquakes and for crossings of the polar cusp, equatorial region and ionospheric trough. All data used in our presentation were gathered by ICE experiment onboard DEMETER satellite. These methods allow to find the energy cascade being a main mechanism of the turbulence developing. Plasma turbulence can be described by the shape of the spectra, the probability distribution function and its moments- kurtosis and skewness. The main goal of our presentation is comparison of these parameters for the turbulence over seismic regions and other ionospheric sites with turbulence.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. 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.

  1. The ionosphere of Venus - Observations and their interpretation

    NASA Technical Reports Server (NTRS)

    Brace, L. H.; Taylor, H. A., Jr.; Gombosi, T. I.; Kliore, A. J.; Knudsen, W. C.; Nagy, A. F.

    1983-01-01

    The implications of Soviet and U.S. observations of the Venus ionosphere's density, temperature, composition, motion, and magnetic structure are discussed, in view of the strong influence exerted on nearly all ionospheric parameters by the solar wind. The IMF conveys solar wind pressure to the ionosphere, compressing, accelerating, heating and removing plasma, forming the ionopause and inducing a nightward convection of plasma. Within the ionosphere, the main electron density peak is at an altitude of about 140 km on the day side, and is believed to be formed by local production and loss analogous to the earth's E region. Throughout most of the ionosphere, the nightward ion flow is primarily driven by the day-to-night pressure gradient, and electron precipitation also contributes to the nightside ionization. The lower atmosphere is dominated by O2(+), except at the lowest altitudes at night, where NO(+) and CO2(+) become significant ions.

  2. 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.

  3. 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.

  4. The Ionospheric Convection and Birkeland Current Response to an Impulse in the Interplanetary Magnetic Field BY Component

    NASA Astrophysics Data System (ADS)

    Wilder, F. D.; Eriksson, S.; Korth, H.; Baker, J. B.; Hairston, M. R.; Heinselman, C. J.; Anderson, B. J.

    2013-05-01

    When the interplanetary magnetic field (IMF) is dawnward or duskward, magnetic merging between the IMF and the geomagnetic field occurs near the cusp on the dayside flanks of the magnetosphere. During these intervals, sunward flow channels on open field lines with velocities in excess of 2 km/s are generated in the polar ionosphere, which can deposit large amounts of energy into the cusp-region thermosphere. In this study, we analyze an interval on 5 April 2010 where there was a strong dawnward impulse in the IMF, followed by a gradual decay in IMF magnitude at constant clock angle. Data from ground based radars and the DMSP spacecraft were assimilated to investigate the global convection pattern during this interval, and data from the Active Magnetospheric and Planetary Electrodynamics Response Experiment (AMPERE) were used to investigate the associated Field-Aligned Current (FAC) system. Additionally, data from AMPERE and the Sondrestrom Incoherent Scatter Radar were used to investigate the time response of the flow channel and its associated FAC pair. We find that there is a delay of approximately 1.25 hours between the arrival of the dawnward IMF impulse at the magnetopause and the speed of the flow channel and strength of the FACs flanking it. In addition to correlation between the dawnward component of the IMF and the flanking FAC strength, we also find that there is inverse correlation between the flanking FAC strength and both the SYM-H index and Solar Wind Alfvenic Mach Number. No statistically significant correlation is found between the flanking FAC strength and solar wind dynamic pressure.

  5. Unfolding plasma density from cylindrical monopole impedance measurements in ionosphere

    NASA Astrophysics Data System (ADS)

    Kiraga, A.

    2003-04-01

    Several common problems occur in measurement techniques and interpretation of plasma natural emissions and impedance data. Antenna characteristics are of prime importance in equivalent circuit analysis. Spacecraft - plasma interaction contributes to variability of equivalent circuit impedances and e.m.f. components and imposes constrains on usefulness of experimental data. In order to have independent, built in estimate of local plasma frequency and to get deeper insight into properties of equivalent circuit for wave diagnostics, impedance measurement was integrated with radio receivers on the ACTIVE, APEX and CORONAS satellites. Impedance measurements of 7.5m long monopole were performed in frequency range .1-10MHz with the frequency step of 50kHz, in voltage divider configuration. Due to high inclination of 82.5deg and altitude range of 500-3000km, data from very different plasmas were collected. Data can be split into quasi normal, disturbed and very disturbed measurements. Equivalent circuit structure evolved in attempt to match even very disturbed measurements. For quasi normal measurements, satisfactory matching is obtained with computed gyrofrequency fc and fitted plasma frequency fn, stray capacitance Cs and capacitance Cv of phenomenological vacuum sheath. With formulas for monopole impedance in cold magnetoplasma, two basic pectral structures are explained. For sufficiently magnetized plasma (roughly fn/fc<2 if Cs=20pF), circuit parallel resonance frequency Fr falls into upper hybrid band (max(fn,fc),fu), resonance amplitude is reduced by high antenna resistance and horn like absolute maximum points fu. For values of fn/fc ratio, greater then critical, Fr is less than fn and broad absolute maximum at Fr follows from low antenna resistance. Further increase of fn/fc results in increasing lag of Fr behind fn. Critical ratio fn/fc increases with decreasing stray capacitance Cs. It follows from data analysis that stray capacitance may change in flight, at least due to attitude changes, so mentioned basic structures may be relevant in stray compensated bridge configuration. It is found that strongly disturbed measurements are related to activation of fast diodes, designed for input protection. Injections of charged particle beams saturated instrument. On line telemetry transmission interfered directly by receipted VHF fields and indirectly by particle acceleration leading to differential charging and direct current flow. In dense equatorial plasma, very peculiar evolution of base voltage spectra is linked to differential charging and intense direct current flow of thermal electrons. Deep, quasi periodic modulations or irregular excursions on time scales much shorter than sweep period are indicative of differential charging by ambient, energetic minor populations. Presented data and simulations address challenges in instrument design, monitoring and onboard data processing.

  6. 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.

  7. Plasma Waves Observed at Low Altitudes in the Tenuous Venus Nightside Ionosphere

    NASA Technical Reports Server (NTRS)

    Strangeway, R. J.; Russell, C. T.; Ho, C. M.; Brace, L. H.

    1993-01-01

    The Pioneer Venus Orbiter Electric Field Detector (OEFD) measured many plasma wave bursts throughout the low altitude ionosphere during the final entry phase of the spacecraft. Apart from 100 Hz bursts observed at very low altitudes (approx. 130 km), the bursts fall into two classes. The first of these is a wideband signal that is observed in regions of low magnetic field, but average densities, in comparison to the prevailing ionospheric condition. This wideband signal is not observed in the 30 kHz channel of the OEFD, but is restricted to the 5.4 kHz channel and lower. Since these bursts are observed with roughly constant burst rate above 160 km altitude, we attribute them to ion acoustic mode waves generated by precipitating solar wind electrons. The second type of signal is restricted to 100 Hz only, and is observed in regions of low electron beta, consistent with whistler-mode waves. These waves could be generated by lightning in the Venus atmosphere if the vertical component of the magnetic field greater than 3.6 nT. Unfortunately, the spacecraft spin axis is mainly horizontal, and only that component of magnetic field can be measured. Alternatively, the 100 Hz bursts could be generated locally through gradient drift instabilities, provided the ambient magnetic field is horizontal. Because the ionosphere is very different during the entry phase, compared to the ionosphere as observed early in the Pioneer Venus mission, any conclusions regarding the source of the plasma waves detected during entry phase cannot be applied directly to the earlier observations.

  8. 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.

  9. Incoherent scatter spectrum of ionospheric plasma with an anisotropic temperature ion distribution

    NASA Astrophysics Data System (ADS)

    Ma, Bao-Ke; Guo, Li-Xin; Su, Hong-Tao; Zhang, Bei-Chen; Hu, Hong-Qiao

    2012-08-01

    The expression of anisotropic temperature ion distribution function under the 13-moment approximation is obtained by solving a set of moment equations based on the Boltzmann equation for a relaxation collision model and with consideration of the anisotropic temperature ion distribution. And the incoherent scatter spectrum with an anisotropic temperature ion distribution is simulated in different directions based on the electromagnetic radiation theory of Sheffield. The effects of different electrical field strengths, ratios of electron temperature to ion temperature, and ion-neutral collision frequencies on the incoherent scatter spectrum are all discussed. Finally, the value of theoretical simulation is compared with the measured value of incoherent scattering spectrum. The result show that the incoherent scatter spectrum of ions seriously deviates from the form of the Maxwellian distribution in the equilibrium state. This phenomenon can be attributed to the effects of anisotropic temperature ion distribution, the larger convection electric field, and other factors in high latitude ionosphere.

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

    SciTech Connect

    Bezrodnyi, V.G.

    1988-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    We report intermediate-scale plasma irregularities in the polar ionosphere inferred from high-resolution radio occultation (RO) measurements using GPS (Global Positioning System) to CASSIOPE (CAScade Smallsat and IOnospheric Polar Explorer) satellite radio links. The high inclination of CASSIOPE and the high rate of signal reception by the GPS Attitude, Positioning, and Profiling RO receiver on CASSIOPE enable a high-resolution investigation of the dynamics of the polar ionosphere with unprecedented detail. Intermediate-scale, scintillation-producing irregularities, which correspond to 1 to 40 km scales, were inferred by applying multiscale spectral analysis on the RO phase measurements. Using our multiscale spectral analysis approach and satellite data (Polar Operational Environmental Satellites and Defense Meteorological Satellite Program), we discovered that the irregularity scales and phase scintillations have distinct features in the auroral oval and polar cap. We found that large length scales and more intense phase scintillations are prevalent in the auroral oval compared to the polar cap implying that the irregularity scales and phase scintillation characteristics are a function of the solar wind and magnetospheric forcings.

  12. 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.

  13. 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.

  14. A global analysis of the electrodynamic interactions between a space station and the ionospheric plasma environment

    NASA Technical Reports Server (NTRS)

    Wang, J.; Hastings, D. E.

    1991-01-01

    A general analysis of the electrodynamic interactions between a space station with two biased platforms and the ionospheric plasma is presented. This problem can be separated into a far-field problem, concerned with the electromagnetic interference surrounding the entire space station, and a near-field problem, concentrated on the interactions in the vicinity of the biased platforms. The far-field problem is solved by application of plasma fluid theory. The space station will generate a radiation field composed mainly of the Alfven waves. This far-field radiation depends on the details of the near-field current collection. Computer particle simulations were performed in the near-field of the biased platform to study the plasma flow field, the sheath structure and the current collection. Approximate analytical solutions to the near-field are also obtained. The far-field and near-field solutions are coupled to provide a global description of the electrodynamic interactions.

  15. 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.

  16. High-latitude plasma convection from Cluster EDI: variances and solar wind correlations

    NASA Astrophysics Data System (ADS)

    Frster, M.; Paschmann, G.; Haaland, S. E.; Quinn, J. M.; Torbert, R. B.; Vaith, H.; Kletzing, C. A.

    2007-07-01

    Based on drift velocity measurements of the EDI instruments on Cluster during the years 2001-2006, we have constructed a database of high-latitude ionospheric convection velocities and associated solar wind and magnetospheric activity parameters. In an earlier paper (Haaland et al., 2007), we have described the method, consisting of an improved technique for calculating the propagation delay between the chosen solar wind monitor (ACE) and Earth's magnetosphere, filtering the data for periods of sufficiently stable IMF orientations, and mapping the EDI measurements from their high-altitude positions to ionospheric altitudes. The present paper extends this study, by looking at the spatial pattern of the variances of the convection velocities as a function of IMF orientation, and by performing sortings of the data according to the IMF magnitude in the GSM y-z plane, |ByzIMF|, the estimated reconnection electric field, Er,sw, the solar wind dynamic pressure, Pdyn, the season, and indices characterizing the ring current (Dst) and tail activity (ASYM-H). The variability of the high-latitude convection shows characteristic spatial patterns, which are mirror symmetric between the Northern and Southern Hemispheres with respect to the IMF By component. The latitude range of the highest variability zone varies with IMF Bz similar to the auroral oval extent. The magnitude of convection standard deviations is of the same order as, or even larger than, the convection magnitude itself. Positive correlations of polar cap activity are found with |ByzIMF| and with Er,sw, in particular. The strict linear increase for small magnitudes of Er,sw starts to deviate toward a flattened increase above about 2 mV/m. There is also a weak positive correlation with Pdyn. At very small values of Pdyn, a secondary maximum appears, which is even more pronounced for the correlation with solar wind proton density. Evidence for enhanced nightside convection during high nightside activity is presented.

  17. 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.

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

    PubMed

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

    2011-07-01

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

  19. 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.

  20. Martian ionospheric plasma densities: First results from MAVEN/LPW of the near-terminator ionosphere in the Northern hemisphere of Mars

    NASA Astrophysics Data System (ADS)

    Andrews, David; McEnulty, Tess; Andersson, Laila; Ergun, Robert; Delory, Gregory; Morooka, Michiko; Fowler, Christopher; Weber, Tristan; Eriksson, Anders; Eparvier, Frank

    2015-04-01

    MAVEN began its science mission at Mars in November 2014. Since then, it has been making measurements with a suite of plasma instrumentation, among which is the Langmuir Probe and Waves (LPW) instrument package. LPW consists of two probes mounted on 7m booms which can be operated as independent Langmuir probes, or jointly as an electric field sensor. LPW can accurately measure the thermal electron plasma density and temperature encountered by the spacecraft during periapsis by performing current-voltage sweeps. Alternatively, the instrument can be operated in 'waves' mode, yielding electric field spectra spanning frequencies in the Hz - MHz range. Additionally, an active sounding mode is available, whereby a low power white-noise signal is fed to the plasma to stimulate the generation of waves at the local plasma frequency. Through these measurement techniques, electron densities accurate to within ~5% can be derived, along with the electron temperature. The instrument cadence and typical spacecraft velocities translate to measurements of the plasma on length scales <20 km. MAVEN's periapsis altitude of ~180 km (dropping lower during "deep dip" campaigns) allow it to conduct in-situ measurements of the ionosphere at altitudes that remain poorly understood. We will present initial results from analysis of the first few months of data taken by LPW, concentrating in particular on plasma density structures observed in the near-terminator ionosphere in the northern hemisphere of Mars.

  1. 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.

  2. 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.

  3. Daytime plasma drifts in the equatorial lower ionosphere

    NASA Astrophysics Data System (ADS)

    Hui, Debrup; Fejer, Bela G.

    2015-11-01

    We have used extensive radar measurements from the Jicamarca Observatory during low solar flux periods to study the quiet time variability and altitudinal dependence of equatorial daytime vertical and zonal plasma drifts. The daytime vertical drifts are upward and have largest values during September-October. The day-to-day variability of these drifts does not change with height between 150 and 600 km, but the bimonthly variability is much larger in the F region than below about 200 km. These drifts vary linearly with height generally increasing in the morning and decreasing in the afternoon. The zonal drifts are westward during the day and have largest values during July-October. The 150 km region zonal drifts have much larger day-to-day, but much smaller bimonthly variability than the F region drifts. The daytime zonal drifts strongly increase with height up to about 300 km from March through October, and more weakly at higher altitudes. The December solstice zonal drifts have generally weaker altitudinal dependence, except perhaps below 200 km. Current theoretical and general circulation models do not reproduce the observed altitudinal variation of the daytime equatorial zonal drifts.

  4. Recent observations of beam plasma interactions in the ionosphere and a comparison with laboratory studies of the beam plasma discharge

    NASA Technical Reports Server (NTRS)

    Bernstein, W.; Kellogg, P. J.; Monson, S. J.; Holzworth, R. H.; Whalen, B. A.

    1982-01-01

    Experimental results from an electron beam injection rocket flight (27:010 AE) launched into an active aurora are summarized. The rocket carried an accelerator which injected programmed electron beams of less than 100 ma at 2 and 4 kV into the ionospheric plasma over the altitude range 120-240 km. A major objective of the experiment was the study of beam-plasma interactions and the possible identification of the ignition of the beam-plasma discharge (BPD) which had been intensively studied in the laboratory. A qualitative assessment of the data indicates that BPD ignition was produced by both 10 ma and Im beams at 2 and 4 kV. Many of the observed characteristics are similar to the BPD characteristics observed in the laboratory.

  5. 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.

  6. Comparison of the USU ionospheric model with the UCL-Sheffield coupled thermospheric-ionospheric model

    NASA Technical Reports Server (NTRS)

    Sojka, J. J.; Schunk, R. W.; Rees, D.; Fuller-Rowell, T. J.; Moffett, R. J.; Quegan, S.

    1992-01-01

    Several physical models of the high-latitude ionosphere have been developed that describe the time-dependent evolution of the E- and F-region plasma density. The models require a variety of inputs, including solar EUV fluxes, magnetospheric convection, auroral precipitation, and neutral atmosphere. Of specific relevance to this study is how the neutral atmosphere is incorporated into the ionospheric models. For the USU ionospheric model, the neutral atmosphere is the MSIS 1986 empirical model, while for the UCL-Sheffield coupled thermospheric-ionospheric model the neutral atmosphere is computed simultaneously with the ionosphere. Both models were run for similar solar and magnetospheric conditions (solar maximum, moderate geomagnetic activity, and winter solstice). Solar maximum conditions ensured a strong coupling between the ionosphere and thermosphere, which provided the possibility of a large ionospheric difference between the two physical models. This was further enhanced by choosing winter conditions so that the densities were not dominated by sunlight. The comparison of the two models indicated that both models predict the same morphological features with similar ionospheric densities, generally within about 30 percent.

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

    SciTech Connect

    Deng, Yongfeng Han, Xianwei; Tan, Yonghua

    2014-06-15

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

  8. 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.

  9. Ionospheric plasma escape by high-altitude electric fields: Magnetic moment ''pumping''

    SciTech Connect

    Lundin, R.; Hultqvist, B.

    1989-06-01

    Measurements of electric fields and the composition of upward flowing ionospheric ions by the Viking spacecraft have provided further insight into the mass dependent plasma escape process taking place in the upper ionosphere. The Viking results of the temperature and mass-composition of individual ion beams suggest that upward flowing ion beams can be generated by a magnetic moment ''pumping'' mechanism caused by low-frequency transverse electric field fluctuations, in addition to a field aligned ''quasi-electrostatic'' acceleration process. Magnetic moment ''pumping'' within transverse electric field gradients can be described as a conversion of electric drift velocity to cyclotron velocity by the inertial drift in time-dependent electric field. This gives an equal cyclotron velocity gain for all plasma species, irrespective of mass. Oxygen ions thus gain 16 times as much transverse energy as protons. In addition to a transverse energy gain above the escape energy, a field-aligned quasi-electrostatic acceleration is considered primarily responsible for the collimated upward flow of ions. The field-aligned acceleration adds a constant parallel energy to escaping ionospheric ions. Thus, ion beams at high altitudes can be explained by a bimodal acceleration from both a transverse (equal velocity) and a parallel (equal energy) acceleration process. The Viking observations also show that the thermal energy of ion beams, and the ion beam width are mass dependent. The average O/sup +//H/sup +/ ''temperature ratio has been found to be 4.0 from the Viking observations. This is less than the factor of 16 anticipated from a coherent transverse electric field acceleration but greater than the factor of 1 (or even less than 1) expected from a turbulent acceleration process. /copyright/ American Geophysical Union 1989

  10. Self-Consistent Magnetosphere-Ionosphere Coupling and Associated Plasma Energization Processes

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Magnetosphere-Ionosphere (MI) coupling and associated with this process electron and ion energization processes have interested scientists for decades and, in spite of experimental and theoretical research efforts, are still ones of the least well known dynamic processes in space plasma physics. The reason for this is that the numerous physical processes associated with MI coupling occur over multiple spatial lengths and temporal scales. One typical example of MI coupling is large scale ring current (RC) electrodynamic coupling that includes calculation of the magnetospheric electric field that is consistent with the ring current (RC) distribution. A general scheme for numerical simulation of such large-scale magnetosphere-ionosphere coupling processes has been presented earlier in many works. The mathematical formulation of these models are based on "modified frozen-in flux theorem" for an ensemble of adiabatically drifting particles in the magnetosphere. By tracking the flow of particles through the inner magnetosphere, the bounce-averaged phase space density of the hot ions and electrons can be reconstructed and the magnetospheric electric field can be calculated such that it is consistent with the particle distribution in the magnetosphere. The new a self-consistent ring current model has been developed that couples electron and ion magnetospheric dynamics with calculation of electric field. Two new features were taken into account in addition to the RC ions, we solve an electron kinetic equation in our model, self-consistently including these results in the solution. Second, using different analytical relationships, we calculate the height integrated ionospheric conductances as the function of precipitated high energy magnetospheric electrons and ions as produced by our model. This results in fundamental changes to the electric potential pattern in the inner magnetosphere, with a smaller Alfven boundary than previous potential formulations would predict but one consistent with recent satellite observations. This leads to deeper penetration of the plasma sheet ions and electrons into the inner magnetosphere and more effective ring current ions and electron energization.

  11. 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.

  12. Plasma bubble registration at altitudes of the topside ionosphere: Numerical evaluations

    NASA Astrophysics Data System (ADS)

    Sidorova, L. N.; Filippov, S. V.

    2014-05-01

    The possibility of registering a plasma bubble at altitudes of the topside ionosphere based on its minor species He+ were studied. The characteristic times of the main aeronomic and electrodynamic processes, in which a bubble and its ion component He+ are involved, were calculated and compared. The recombination processes of helium ions in a bubble, the vertical transfer of a plasma bubble as a whole, and the diffusion transfer of the plasma bubble minor constituent (He+) were considered. The characteristic times of ambipolar and transverse (Bohm) diffusion were calculated when the diffusion transfer was estimated. The effect of the photoionization processes on plasma bubble dissipation were estimated based on the He+ bubble ion component. It was shown that the bubble filling characteristic time with an average He+ depletion to the He+ ambient density is 24 h. It was concluded that such a prolonged bubble lifetime makes it possible to register a plasma bubble reliably over approximately two days. However, it has been noted that only a residual plasma bubble structure, i.e., its trace visible in He+ ions, will apparently be registered during most prolonged observations.

  13. The relative importance of dayside and nightside reconnection on the ionospheric convection system during sudden enhancements of solar wind dynamic pressure: OpenGGCM-CTIM results

    NASA Astrophysics Data System (ADS)

    Connor, H. K.; Zesta, E.; Ober, D. M.; Raeder, J.

    2013-12-01

    Recent studies have shown that sudden enhancement of solar wind dynamic pressure (Psw) is a significant driver of energy transfer to the magnetosphere-ionosphere (MI) system, generating strong responses such as increase in the cross polar cap potential (CPCP), reduction of the polar cap area, expansion of the auroral oval, etc. This study investigates where, when, and how solar wind energy is deposited into the MI system during sudden solar wind dynamic pressure enhancement, like shocks. We analyze three unique events that occurred during strongly southward, near-zero Bz, and northward IMF by simulating the MI responses with the OpenGGCM-CTIM coupled magnetosphere-ionosphere model. We examine the behavior of dayside and nightside reconnection, and quantify their respective contribution to CPCP, a proxy of ionospheric flow convection. The dayside and nightside reconnection rates (Rd and Rn) are defined to be the open flux per unit time crossing the dayside and nightside open-closed field line boundaries. The relative contributions to CPCP are estimated by fitting the reconnection rates and the modeled CPCP to a widely used linear equation, CPCP = CdRd + CnRn + viscosity, where the correlation coefficients of dayside and nightside reconnection rates Cd and Cn define the quantitative contribution of each merging rate. The model results reproduce the CPCP increase at the arrival of the Psw enhancement, showing good agreement with the observations of Defense Meteorological Satellite Program (DMSP) spacecraft and predictions from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique. For all three events, the dayside reconnection reacts first, increasing its rate right after the Psw increase. The nightside reconnection intensifies about 10-20 minutes later due to the solar wind propagation to the magnetotail. For southward IMF, dayside reconnection contributes to the CPCP increase twice as much as the nightside one, while for northward IMF, nightside reconnection dominates.

  14. 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.

  15. A simulation study on the impact of altitudinal dependent vertical plasma drift on the equatorial ionosphere in the evening

    NASA Astrophysics Data System (ADS)

    Qian, Cheng; Lei, Jiuhou; Wang, Wenbin

    2015-04-01

    We carry out a simulation study on the impact of altitudinal dependent plasma drift on the equatorial ionosphere in the evening, under geomagnetically quiet conditions. Our study used the vertical plasma drift velocity data measured by an incoherent scatter radar at Jicamarca (11.95S, 76.87W). The data covered the local sunset period on 15 and 16 November 2004. The plasma drift had significant altitudinal variations in the vertical component, which is perpendicular to the magnetic field. We employed SAMI2 (SAMI2 is another model of the ionosphere) to evaluate the effect of the altitude-dependent ion drift on the equatorial ionosphere. Three types of plasma drift velocity inputs were used in our simulations. The first input is calculated from an empirical model, the second is a height-averaged drift obtained from the observed drift velocity, and the third one corresponds to the observed altitudinal dependent drift data. A strong equatorial ionization anomaly occurred in the results of all numerical experiments. Additional layers (F3 layers) in electron densities over the equatorial F region and "arch" latitudinal structures extending to lower middle latitudes were seen in the simulations driven by the observed altitudinal dependent drift. We further show that neutral winds do not have a significant effect on the simulated F3 layers. The results of our numerical experiments suggest that the simulated additional ionospheric layers and arch structures are associated with the altitudinal gradients in the vertical plasma drift velocity.

  16. Turbulent transport and heating in the auroral plasma of the topside ionosphere

    NASA Technical Reports Server (NTRS)

    Ionson, J. A.; Ong, R. S. B.; Fontheim, E. G.

    1979-01-01

    Using plasma parameters from a typical stormtime ionospheric energy balance model, we have investigated the effects of plasma turbulence on the auroral magnetoplasma. The turbulence is assumed to be comprised of electrostatic ion cyclotron waves. These waves have been driven to a nonthermal level by a geomagnetic field-aligned, current-driven instability. The evolution of this instability is shown to proceed in two stages and indicates an anomalous increase in field-aligned electrical resistivity and cross-field ion thermal conductivity as well as a decrease in electron thermal conductivity along the geomagnetic field. In addition, this turbulence heats ions perpendicular to the geomagnetic field and hence leads to a significant ion temperature anisotropy.

  17. Auroral ionospheric signatures of the plasma sheet boundary layer in the evening sector

    NASA Technical Reports Server (NTRS)

    Burke, W. J.; Machuzak, J. S.; Maynard, N. C.; Basinska, E. M.; Erickson, G. M.; Hoffman, R. A.; Slavin, J. A.; Hanson, W. B.

    1994-01-01

    We report on particles and fields observed during Defense Meteorological Satellite Program (DMSP) F9 and DE 2 crossings of the polar cap/auroral oval boundary in the evening magnetic local time (MLT) sector. Season-dependent, latitudinally narrow regions of rapid, eastward plasma flows were encountered by DMSP near the poleward boundary of auroral electron precipitation. Ten DE 2 orbits exhibiting electric field spikes that drive these plasma flows were chosen for detailed analysis. The boundary region is characterized by pairs of oppositely-directed, field-aligned current sheets. The more poleward of the two current sheets is directed into the ionosphere. Within this downward current sheet, precipitating electrons either had average energies of a few hundred eV or were below polar rain flux levels. Near the transition to upward currents, DE 2 generally detected intense fluxes of accelerated electrons and weak fluxes of ions, both with average energies between 5 and 12 keV. In two instances, precipitating ions with energies greater than 5 keV spanned both current sheets. Comparisons with satellite measurements at higher altitudes suggest that the particles and fields originated in the magnetotail inside the distant reconnection region and propagated to Earth through the plasma sheet boundary layer. Auroral electrons are accelerated by parallel electric fields produced by the different pitch angle distributions of protons and electrons in this layer interacting with the near-Earth magnetic mirror. Electric field spikes driving rapid plasma flows along the poleward boundaries of intense, keV electron precipitation represent ionospheric responses to the field-aligned currents and conductivity gradients. The generation of field-aligned currents in the boundary layer may be understood qualitatively as resulting from the different rates of earthward drift for electrons and protons in the magnetotail's current sheet.

  18. 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.

  19. 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.

  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. 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.

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

    SciTech Connect

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

    2013-05-15

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

  3. The thresholds of ionospheric plasma instabilities pumped by high-frequency radio waves at EISCAT

    NASA Astrophysics Data System (ADS)

    Bryers, C. J.; Kosch, M. J.; Senior, A.; Rietveld, M. T.; Yeoman, T. K.

    2013-11-01

    We test the existing theories regarding the thresholds for the parametric decay instability (PDI), the oscillating two-steam instability (OTSI), and the thermal parametric instability (TPI) using the European Incoherent Scatter (EISCAT) facility's ionospheric heater. In these processes, the pump wave can couple to various electrostatic waves in the F layer ionosphere, which can be observed using the EISCAT UHF radar (PDI and OTSI) or by HF radar (TPI). On 19 October 2012, the heater power was stepped from 0.5 MW to 100 MW effective radiated power in seven steps using a 1 min on, 1 min off cycle. We use an electric field model, taking into account D region absorption, to compare theory with our observations. In all three cases, we find good agreement. In addition, the growth of striations formed during the TPI causes anomalous absorption of the heater wave, which we observe as decreased UHF ion line and plasma line backscatter power. We show evidence that heating for a prolonged period of time reduces the UHF ion line intensity throughout the experiment.

  4. The collective gyration of a heavy ion cloud in a magnetized plasma. [in earth ionosphere

    NASA Technical Reports Server (NTRS)

    Brenning, N.; Swenson, C.; Kelley, M. C.; Providakes, J.; Torbert, R.

    1992-01-01

    Results are reported from the ionospheric barium injection experiments CRIT I and CRIT II, during both of which a long-duration oscillation was observed with a frequency close to the gyrofrequency of barium and a time duration of about 1 sec. A model for the phenomenon which was proposed for CRIT I is compared to the results from CRIT II, which made a much more complete set of measurements. The model follows the motion of a low-beta ion cloud through a larger ambient plasma. As the ions move across the magnetic field, the space charge is continuously neutralized by magnetic-field aligned electron currents from the ambient ionosphere, drawn by the divergence in the perpendicular electric field. These currents yield a perturbation of the magnetic field related to the electric perturbation by Delta-E/Delta-B is approximately equal to V sub A. The possibility of extending the model to the active region, where the ions are produced in this type of self-ionizing injection experiments, is discussed.

  5. Plasma wave turbulence due to the wake of an ionospheric sounding rocket

    NASA Astrophysics Data System (ADS)

    Endo, K.; Kumamoto, A.; Ono, T.; Katoh, Y.

    2013-12-01

    In the ionosphere, a rarefied plasma region called "plasma wake" is formed behind a sounding rocket. Based on a one-dimensional Vlasov-Maxwell simulation, it was suggested that electron distribution functions in the plasma wake behind spacecraft are different from the Maxwell-Boltzmann distribution function [Singh et al., 1987]. Thus, plasma waves are expected to be generated in the wake of a sounding rocket. Some studies reported plasma waves around the wake of artificial satellites [Keller et al., 1997] and solar system bodies such as Moon [Nakagawa et al., 2003]. Yamamoto (2000) is the first study that focused on plasma waves induced by sounding rockets on the basis of the results of several rocket experiments. He compared the observed wave frequency with the electron number density in the wake and indicated plasma waves could be generated inside the rocket wake. In order to investigate the properties of the waves in more detail (e.g. spin-phase dependence, generation mechanism, etc.), we are now analyzing the data of electron number density and electric fields of plasma waves in mid-latitude ionosphere by an impedance probe and a plasma wave receiver, which were installed on the sounding rocket S-520-26. In the analysis, we have found plasma waves in a frequency range of 1.3-2.4 MHz (hereinafter called Group-A) as well as those in a frequency range between 0.02 MHz to about 0.6 fce (Group-B), and those in a frequency range from about 0.5 fce to 0.9 fce (Group-C), where fce is the electron cyclotron frequency deduced from the IGRF model. The Group-A emissions are similar to the waves observed in previous studies [Yamamoto, 2000]. Comparison with the data of the impedance probe has suggested the Group-A waves are short-wavelength electrostatic waves including upper-hybrid resonance (UHR) mode waves and electrostatic electron cyclotron harmonic (ESCH) waves. On the other hand, the Group-B and Group-C waves are whistler mode waves. Besides, the analysis with the rocket attitude data has clarified that the Group-A emissions are enhanced when the antenna element pointed in the directions of 320-20 and 150-250 in spin-phase angle while that the Group-B waves have been observed clearly when the antenna element pointed to 50-110 and 200-300, and that the Group-C waves are found in 90-160. The spin-phase dependences suggest inhomogeneous distributions of the occurrence regions of plasma instabilities with respect to the wake structure, or anisotropy of the wave propagation in plasma. In order to discuss the generation mechanism of the observed plasma waves, we have performed numerical calculations of linear growth rate of plasma waves by assuming anisotropic velocity distribution functions with an electron beam or temperature anisotropy. As a result, we could confirm positive linear growth rates in wave numbers and frequency ranges of UHR mode waves, ESCH waves, and electrostatic whistler mode waves. Actual distribution functions around the rocket wake, however, might not be simple as we assumed. Therefore, further studies with using Vlasov-Maxwell simulation will be needed.

  6. Cluster EDI convection measurements across the high-latitude plasma sheet boundary at midnight

    NASA Astrophysics Data System (ADS)

    Quinn, J. M.; Paschmann, G.; Torbert, R. B.; Vaith, H.; McIlwain, C. E.; Haerendel, G.; Bauer, O.; Bauer, T. M.; Baumjohann, W.; Fillius, W.; Foerster, M.; Frey, S.; Georgescu, E.; Kerr, S. S.; Kletzing, C. A.; Matsui, H.; Puhl-Quinn, P.; Whipple, E. C.

    2001-10-01

    We examine two crossings of three Cluster satellites from the polar cap into the high-latitude plasma sheet at midnight local time, using data from the Electron Drift Instrument (EDI). EDI measures the full electron drift velocity in the plane perpendicular to the magnetic field for any field and drift directions. The context of the measured convection velocities is established by their relation to the intense enhancements in 1 keV electrons, also measured by EDI, as the satellites move from the polar cap into the plasma sheet boundary. In both cases presented here, the cross B convection in the polar cap is anti-sunward (toward the nightside plasma sheet) with a small duskward component. As the satellites enter the plasma sheet boundary region, the dawn-dusk convective flow component reverses its sign, and the flow in the meridianal plane (toward the center of the plasma sheet) drops substantially. The relatively stable convection in the polar cap becomes highly variable as the PSBL is encountered. The timing and sequence of the boundary crossings by the Cluster satellites are consistent with a relatively static structure on a time scale of the few minutes in satellite separations. In one of the two events, the plasma sheet boundary has a spatially separate structure that is crossed by the satellites before entering the plasma sheet.

  7. 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.

  8. 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.

  9. 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.

  10. The 10 sheath-accelerated electrons and ions. [atmospheric models of plasma sheaths and ionospheric electron density

    NASA Technical Reports Server (NTRS)

    Shawhan, S. D.

    1975-01-01

    A model is presented that suggests that plasma sheaths form between the ionospheric plasma moving with Io and the ambient plasma corotating with Jupiter. Potentials across these sheaths could be as high as 580 kV which is the motional emf across Io's ionosphere. Electrons and ions can be accelerated across these sheaths. The sheaths may exist at the top of the Io ionosphere with characteristic thicknesses of 1/4 kilometers. The model is consistent with the Pioneer observations of 0.15 MeV electrons at the inner edge of Io's L-shell and the enhanced number density of low-energy protons at the outer edge. Ion sputtering of the Io surface is discussed and may explain the presence of atomic hydrogen and sodium in the vicinity of Io. Also these accelerated particles may be important to the formation of the Io ionosphere. High electron flux which may lead to decametric radio emissions, Jovian atmospheric heating and optical and X-ray emissions is also discussed.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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 (23.2N, 77.6E); geomagnetic coordinates (14.29 N, 151.12E)] 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.

  13. Plasma wave turbulence due to the wake of an ionospheric sounding rocket

    NASA Astrophysics Data System (ADS)

    Endo, Ken; Kumamoto, Atsushi; Oya, Hiroshi; Ono, Takayuki; Katoh, Yuto

    2013-04-01

    A sounding rocket moving in the ionosphere generally interacts with surrounding plasma. Because this affects in-situ measurement data, it is very important to understand the physics of the interaction between the ionosphere and a moving vehicle. For instance, a rarefied plasma region called "plasma wake" is formed behind a sounding rocket. Several previous studies based on rocket experiments have suggested that upper-hybrid resonance (UHR) mode waves are excited in a rocket wake. A wake turbulence model has been proposed as a possible explanation for the waves where two stream instability occurs in the wake center owing to the incident plasma flow from the both sides of the wake edges. Thus, plasma waves are generated and have been observed by the wave receivers onboard the rockets. Plasma waves in a wake have been reported not only around sounding rockets but also around solar system bodies such as Moon. As for a rocket wake, the generation mechanism of the waves has been investigated by using wave receivers with time resolutions worse than 500 msec. They are, however, not enough for detailed investigations about the plasma wave generations and propagations. To discuss the properties of the plasma waves caused around a rocket wake, we have analyzed the data of electric fields and electron number density in the S-520-26 sounding rocket experiment, which was performed at Uchinoura, Japan, on January 12, 2012. The rocket reached an altitude of 298 km, and the data has been obtained four or five times in one spin period of the rocket by using a newly developed digital plasma wave monitor and an impedance probe, whose time resolutions are about 260 msec. In the observation, enhancement of plasma waves has been observed in two frequency ranges from 0.02 to 0.9 MHz (LF range), and from 1.3 to 2.4 MHz (MF range). The frequency range of the MF emissions is around the UHR frequency, which is determined based on the IGRF magnetic field model and electron number density measured by the impedance probe. However, the lowest frequency of the emissions is almost the same as the Z-mode cutoff frequency, particularly in higher altitude range than 280 km. The wave spectra are similar to those observed by the previous studies. The frequency range of the LF emissions is found to be that of whistler mode branch. Based on the rocket attitude, it is suggested that the electric fields of the LF and MF emissions are nearly perpendicular and parallel to the wake structure, respectively. If we can assume that the observed waves are generated around the rocket, they have to be electrostatic waves because the wave length should be shorter than the size of the disturbed region. We have performed calculations of plasma dispersion relations with assuming some anisotropic velocity distribution functions of electrons expected around the wake, and deduced the linear growth rates, group velocities, etc. We compare the observational results with calculated ones, and discuss the generation mechanisms of the plasma waves.

  14. 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.

  15. Characterization of the dynamic variations of the dayside high-latitude ionospheric convection reversal boundary and relationship to interplanetary magnetic field orientation

    NASA Astrophysics Data System (ADS)

    Ridley, A. J.; Clauer, C. R.

    1996-05-01

    We present initial results from observations of the northern summer polar ionospheric convection reversal boundary using ground- and satellite-based instrumentation. Ionospheric convection measurements obtained using the Sondrestrom radar are used to locate and observe the boundary. The flow around the reversal is compared to three different modeled low patterns. The first is a shear reversal (oppositely directed flows with no flow across the boundary). The second is a shear reversal combined with uniform poleward flow. The final flow pattern observed is a rotational reversal, where flows gradually turn from one direction to the opposite over distances on the order of 200-400 km. The convection reversals observed were categorized into three different classes: (1) stationary and steady, (2) nonstationary, and (3) oscillating. A stationary and steady boundary remains at the same invariant latitude for long periods of time and demonstrates no observable motion. A nonstationary boundary will propagate northward or southward, generally remaining parallel to a line of invariant latitude. The oscillating reversal boundary (ORB) will have wave-like motions of the local boundary location. A number of different reversals were classified and then studied further using other instrumentation, which include the Greenland coastal and MAGIC chains of magnetometers, the drift meter and particle precipitation instruments from the DMSP F9, F10, and F11 satellites, and interplanetary magnetic field (IMF) measurements from the IMP 8 satellite. A stationary and steady reversal has been observed during a time of magnitude variations in the By and Bz components of the IMF, but no sign changes in either of the components. The nonstationary reversals have been observed to be a response to both sign changes and magnitude changes with no sign changes in IMF components. Of the two ORBs reported here, one has been determined to be a ULF wave propagating along the convection reversal boundary, which maps to the magnetospheric low latitude boundary layer. The other ORB has little coherence between longitudinally spaced magnetometer stations, implying that the propagating waves are changing form between the stations.

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

    NASA Astrophysics Data System (ADS)

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

    1989-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  19. 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.

  20. 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

  1. 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.

  2. Ionospheric plasma bubbles observed concurrently by multi-instruments over low-latitude station Hainan

    NASA Astrophysics Data System (ADS)

    Wang, G. J.; Shi, J. K.; Reinisch, B. W.; Wang, X.; Wang, Z.

    2015-03-01

    Previous studies have shown that the ionospheric "strong range spread F" (SSF) closely correlates with the occurrence of scintillations caused by equatorial plasma bubbles. However, there is no report on concurrent observations of SSF and bubbles with in situ measurement. This paper discusses two cases of concurrent observations with a DPS4 Digisonde and a collocated scintillation monitor at the low-latitude station Hainan (19.5N, 109.1E), and with in situ ion density measurements made by the ROCSAT-1 satellite. Two case studies were made for 10 and 23 April 2004, respectively. In both cases, the SSF occurred before midnight and lasted more than 3.5 h. The scintillations were accompanied with strong range SF. Concurrently, the ROCSAT-1 satellite observed plasma bubbles over Hainan station. In the first case, two bubbles were observed by the satellite with east-west sizes of more than ~200 km over Hainan station. Two bubbles were also observed in the second case with east-west extensions of about 220 km and 35 km, respectively. For the first time, direct observational evidence is provided for the causal relationship between equatorial plasma bubbles with in situ measurement and the concurrent occurrence of SSF and strong scintillations.

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

    SciTech Connect

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

    1995-05-01

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

  4. 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.

  5. 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.

  6. The flow of plasma in the solar terrestrial environment

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.; Birmingham, T. J.

    1992-01-01

    The scientific goals of the program are outlined, and some of the papers submitted for publication within the last six months are briefly highlighted. Some of the topics covered include ionosphere-magnetosphere coupling, polar cap arcs, polar wind, convection vortices, ionosphere-plasmasphere coupling, and the validity of macroscopic plasma flow models.

  7. Convective velocity reversal caused by turbulence transition in tokamak plasma.

    PubMed

    Zhong, W L; Zou, X L; Bourdelle, C; Song, S D; Artaud, J F; Aniel, T; Duan, X R

    2013-12-27

    Particle transport has been studied in the Tore Supra tokamak by using modulated ion cyclotron resonance heating to generate perturbations of density and temperature. For the first time, a reversal of the particle convective velocity and a strong increase in the turbulent particle flux have been clearly observed. When the mixed critical gradient ?c=R/L(T)+4(R/L(n))=22 is exceeded, the particle flux increases sharply and the convective velocity reverses from inward to outward. These observations are in agreement with quasilinear, gyrokinetic calculations. The critical gradient corresponds to a transition from an instability driven by the ion temperature gradient to the onset of another instability caused by trapped electrons. PMID:24483800

  8. Dominance of convective heat transport in the core of TFTR (Tokamak Fusion Test Reactor) supershot plasmas

    SciTech Connect

    Kissick, M.W.; Efthimion, P.C.; Mansfield, D.K.; Callen, J.D.; Bush, C.E.; Park, H.K.; Schivell, J.; Synakowski, E.J.; Taylor, G.

    1993-08-01

    Using perturbations in electron density and temperature induced by small Helium gas puffs in TFTR (Tokamak Fusion Test Reactor) the dominance of convective heat transport in the core (r/a < 0.4) of supershot plasmas has been demonstrated in a new way. The TRANSP transport code was used to calculate the time-dependent particle and heat fluxes. Perturbations in the calculated convective and total electron heat fluxes were compared. They demonstrate that the conductive component decreases moving into the supershot core, and the convective component dominates in the supershot core. These results suggest a different transport drive in the supershot core compared to that in the rest of the supershot plasma.

  9. 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.

  10. 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.

  11. A simulation study of radial expansion of an electron beam injected into an ionospheric plasma

    NASA Technical Reports Server (NTRS)

    Koga, J.; Lin, C. S.

    1994-01-01

    Injections of nonrelativistic electron beams from a finite equipotential conductor into an ionospheric plasma have been simulated using a two-dimensional electrostatic particle code. The purpose of the study is to survey the simulation parameters for understanding the dependence of beam radius on physical variables. The conductor is charged to a high potential when the background plasma density is less than the beam density. Beam electrons attracted by the charged conductor are decelerated to zero velocity near the stagnation point, which is at a few Debye lengths from the conductor. The simulations suggest that the beam electrons at the stagnation point receive a large transverse kick and the beam expands radially thereafter. The buildup of beam electrons at the stagnation point produces a large electrostatic force responsible for the transverse kick. However, for the weak charging cases where the background plasma density is larger than the beam density, the radial expansion mechanism is different; the beam plasma instability is found to be responsible for the radial expansion. The simulations show that the electron beam radius for high spacecraft charging cases is of the order of the beam gyroradius, defined as the beam velocity divided by the gyrofrequency. In the weak charging cases, the beam radius is only a fraction of the beam gyroradius. The parameter survey indicates that the beam radius increases with beam density and decreases with magnetic field and beam velocity. The beam radius normalized by the beam gyroradius is found to scale according to the ratio of the beam electron Debye length to the ambient electron Debye length. The parameter dependence deduced would be useful for interpreting the beam radius and beam density of electron beam injection experiments conducted from rockets and the space shuttle.

  12. Response of the convecting high-latitude F layer to a powerful HF wave

    NASA Astrophysics Data System (ADS)

    Mingaleva, G. I.; Mingalev, V. S.

    1997-10-01

    A numerical model of the high-latitude ionosphere, which takes into account the convection of the ionospheric plasma, has been developed and utilized to simulate the F-layer response at auroral latitudes to high-power radio waves. The model produces the time variations of the electron density, positive ion velocity, and ion and electron temperature profiles within a magnetic field tube carried over an ionospheric heater by the convection electric field. The simulations have been performed for the point with the geographic coordinates of the ionospheric HF heating facility near Tromso, Norway, when it is located near the midnight magnetic meridian. The calculations have been made for equinox, at high-solar-activity, and low-geomagnetic-activity conditions. The results indicate that significant variations of the electron temperature, positive ion velocity, and electron density profiles can be produced by HF heating in the convecting high-latitude F layer.

  13. Nonlinear dynamics of the 3D Alfvn waves in plasma of ionosphere and magnetosphere

    NASA Astrophysics Data System (ADS)

    Belashov, Vasily Yu.; Belashova, Elena S.

    2015-12-01

    The nonlinear dynamics of the 3D solitary Alfvn waves propagating nearly parallel to the external magnetic field in plasma of ionosphere and magnetosphere, which are described by the model of the 3-DNLS equation, is studied analytically and numerically. Under the assumption of negligible dissipative effects the analytical estimates and the sufficient conditions for the stability of 3D solutions of the 3-DNLS equation are obtained, based on the transformational properties of the system's Hamiltonian for the whole range of the equation coefficients. On the basis of asymptotic analysis the solutions asymptotics are presented. To study the evolution of the 3D Alfvn solitary waves including propagation of the Alfvn waves' beams in a magnetized plasma the equation are integrated numerically using the simulation codes specially developed. The results show that the 3-DNLS equation in non-dissipative case can have the stable 3D solutions in form of the 3D Alfvn solitons, and also on a level with them the 3D solutions collapsing or dispersing with time. In terms of the self-focusing phenomenon the results obtained can be interpreted as the formation of the stationary Alfvn wave beam propagating nearly parallel to magnetic field, or Alfvn wave beam spreading, or the self-focusing of the Alfvn wave beam. The influence of the dissipation in the medium on structure and character of evolution of 3D Alfvn waves is studied.

  14. Airglow enhancements associated with plasma cavities formed during ionospheric heating experiments

    SciTech Connect

    Bernhardt, P.A. ); Tepley, C.A. ); Duncan, L.M. )

    1989-07-01

    Optical measurements made at the Arecibo Observatory during the 1987 heating campaign showed large temporal and spatial variations in 630.0-nm airglow enhancements during times of continuous power transmissions of high-power radio waves. Photometric data displayed fluctuations of 60 R or more in the red-line (630.0 nm) emission from atomic oxygen. These fluctuations were associated with heater-induced cavities which drifted and evolved in the modified ionosphere. Data from the Arecibo incoherent scatter radar were used in conjunction with airglow images to provide a physical interpretation of the modification process. Electrons were accelerated by large amplitude Langmuir waves excited by parametric decay instabilities occurring near the wave reflection points inside the density cavities. Inelastic collisions with oxygen atoms produced excited states which yielded enhanced 630.0-nm and 557.7-nm emissions. A numerical model has been used to relate the enhanced airglow intensities to the energy spectrum of the accelerated electrons. The measured airglow could have been produced by an isotropic source at 340 km altitude that accelerated 0.01% of the ambient electrons into a suprathermal Maxwellian distribution with a temperature of 2.05 eV. Experimental and theoretical studies suggest that airglow clouds were directly coupled to plasma density cavities because (1) these cavities trapped the HF radio beam and (2) electrons accelerated out into regions of reduced plasma concentration were less effectively thermalized and, consequently, were more effective for collisional excitation of neutral species.

  15. Reduction of Raman scattering in a plasma to convective levels using induced spatial incoherence

    SciTech Connect

    Obenschain, S.P.; Pawley, C.J.; Mostovych, A.N.; Stamper, J.A.; Gardner, J.H.; Schmitt, A.J.; Bodner, S.E.

    1989-02-13

    We present measurements of the Raman backscatter produced by laser-plasma interaction where the laser focal profile was smoothed by induced spatial incoherence (ISI). The Raman backscatter with the ISI beam is much smaller than that with an ordinary beam. The onset of Raman backscattering with ISI followed the predictions of a convective gain model to within 30% in intensity.

  16. High latitude ionospheric winds related to solar-interplanetary conditions

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1973-01-01

    Treated jointly, two recent results imply that the distribution of winds in the polar ionosphere should change as a function of the direction of the interplanetary magnetic field. (1) From the motions of chemically released ion and neutral clouds, it is apparent that neutral winds in the high latitude ionosphere are driven principally by ion drag forces. (2) OGO-6 electric field measurements have demonstrated that there are definite relationships between the time-latitude distribution of ionospheric plasma convection and interplanetary magnetic field parameters, and also that the distribution is most sensitive to the azimuthal angle of the interplanetary field. Although direct neutral wind to interplanetary magnetic field comparisons are not available, logic clearly implies a close relationship. The lower altitude, meteorological effects of these externally driven ionospheric winds are not known. However, observations of infrasonic waves following sudden ionization enhancements indicate the existence of momentum transfer.

  17. 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.

  18. Magnetosheath-ionospheric plasma interactions in the cusp/cleft. 1: Observations of modulated injections and upwelling ion fluxes

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Menietti, J. D.; Peterson, W. K.; Burch, J. L.; Waite, J. H., Jr.; Giles, B.

    1993-01-01

    In situ observations of the cusp/cleft are important as they allow a direct investigation of coupling solar wind energy to the ionosphere, plus they provide an opportunity for the remote sensing of the magnetopause. High time resolution observations from Dynamic Explorer 1 are used to investigate these processes. It is shown that in the spacecraft frame the injection is modulated or pulsating with a period of approximately 18-30 s with the injection duration possibly being as short as 6 s. This modulation indicates that there may be fast time scale and/or short scale length processes modulating the injection of the magnetosheath plasma across the magnetopause. In addition, the pulsating injection is seen to modulate the outflow of upwelling ionospheric ions to the magnetosphere. These upwelling ions are seen prior to the magnetosheath ion injection and therefore are not directly created by the injection. During the injection itself, the intensity of the upwelling ions is seen to dramatically decrease but their average energy increases. At end of the magnetosheath injections, the intensity of the upwelling ion flux is seen to increase to levels comparable to levels prior to the magnetosheath injection. On two occasions during the encounter, the particle fluxes are sufficiently high that enhanced downward flows of perpendicularly heated ions, of presumably ionospheric origin, are observed in association with a reduction in the intensity of the upwelling ions. These observations are probably the first detection of downward conics and suggest that there is momentum transfer between the magnetosheath and ionospheric ions. This momentum transfer eventually leads to an enhanced outflow of heated ionospheric plasma where their energy has been raised from a few tens of eV to a few hundred eV.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. First CLUSTER plasma and magnetic field measurements of flux transfer events in conjunction with their ionospheric flow signatures

    NASA Astrophysics Data System (ADS)

    Rae, I. J.; Taylor, M. G.; Lavraud, B.; Cowley, S. W.; Lester, M.; Fenrich, F. R.; Fazakerley, A.; Rème, H.; Sofko, G.; Balogh, A.

    2001-12-01

    The launch of the Cluster satellite constellation allows, amongst other things, the study of the small-scale spatio-temporal structures in the near-Earth geospace. We present a case study of the high-altitude northern hemispheric cusp by the Cluster-II spacecraft constellation under southward IMF conditions. During this interval Cluster traversed the northern hemispheric dayside region and crossed the magnetopause close to the noon-midnight meridian, and observed both the plasma and magnetic field observations of transient reconnection for a number of hours. Throughout this interval, the ionospheric footprint of the spacecraft maps into the Canadian sector of the Earth's ionosphere into the Saskatoon and Kapuskasing HF radars fields-of-view. This SuperDARN HF radar pair observe the ionospheric flows generated by this transient reconnection during this interval at approximately the same magnetic latitude and local time. The calculated orientation of the reconnected flux tubes is found to be in accordance with the prevailing IMF conditions and the direction of motion of the excited ionospheric flows. We discuss these observations in terms of transient magnetic flux transfer and in terms of the size and location of the active reconnection X-line at the low-latitude magnetopause.

  4. 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).

  5. Mechanisms underlying the prereversal enhancement of the vertical plasma drift in the low-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Eccles, J. V.; St. Maurice, J. P.; Schunk, R. W.

    2015-06-01

    The evening prereversal enhancement (PRE) of the vertical plasma drift has important consequences for the Appleton density anomaly and the stability of the nighttime ionosphere. Simplified simulations were used to review the three competing theories of the PRE origin, to explore their relative importance, and to indentify their interdependence. The mechanisms involved in the generation and climatology of the PRE are, first, a curl-free electric field response to rapid changes in the vertical electric field associated with the nighttime F region dynamo; second, a divergence of Hall currents in the E region away from the magnetic equator; and, third, the moderating effect of the large Cowling conductivities in the equatorial E region. The simulations indicate that the equatorial Cowling conductivity creates an important current path that limits the other two mechanisms prior to equatorial sunset and releases them after equatorial sunset. The curl-free mechanism is the dominant mechanism when the terminator and magnetic meridian are aligned in part due to the accelerating F region zonal wind. When the solar terminator is not aligned with the magnetic meridian, there is an interaction involving all three mechanisms contributing to the magnitude and timing of the PRE. Finally, the altitude profile of the PRE decays more quickly with altitude when the curl-free mechanism dominates as compared to when the Hall current mechanism dominates.

  6. 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.

  7. 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.

  8. Radiative divertor plasmas with convection in DIII-D

    SciTech Connect

    Leornard, A.W.; Porter, G.D.; Wood, R.D.

    1998-01-01

    The radiation of divertor heat flux on DIII-D is shown to greatly exceed the limits imposed by assumptions of energy transport dominated by electron thermal conduction parallel to the magnetic field. Approximately 90% of the power flowing into the divertor is dissipated through low Z radiation and plasma recombination. The dissipation is made possible by an extended region of low electron temperature in the divertor. A one-dimensional analysis of the parallel heat flux finds that the electron temperature profile is incompatible with conduction dominated parallel transport. Plasma flow at up to the ion acoustic speed, produced by upstream ionization, can account for the parallel heat flux. Modeling with the two-dimensional fluid code UEDGE has reproduced many of the observed experimental features.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Current system in the top ionosphere generated relativistic electrons, let out by a cloud of radioactive plasma

    NASA Astrophysics Data System (ADS)

    Stupitsky, E. L.; Kurnosov, V. V.; Lavrinenko, N. E.

    In experiments such as Starfisch extending radioactive plasma radiates into a geomagnetic ionosphere a powerful stream of relativistic electrons Being distributed along a geomagnetic field beta-electrons form self-coordinated current system and generate electromagnetic indignations Using 3D calculations of behaviour of a cloud of radioactive plasma and numerical modelling of movement beta-electrons inside and outside of a plasma cloud the share from total emitted electrons which is capable to be grasped by the non-uniform geomagnetic field superseded from plasma is determined and to participate in formation current system It is shown that the radius of the current tube depends on radial distribution of plasma and in a non-uniform magnetic field it is much less than the radius of the sphere The amplitude of the current is proportional to activity of the plasma source and inside this source essentially depends on the speed of leaving electrons into tubes of current The dynamics of electrons in a tube of current their interaction with the top ionosphere and the self-coordinated electric field was calculated numerically on the basis of a method of plasma sheets It is shown that if the height of a plasma source exceeds 120 km there is an effect of partial lock-out of an output of electrons under the self-coordinated electric field If the height of the source is about 300 km then in 5 cdot 10 -3 second a quasistationary mode of development of current system is realized Thus the first group of electrons penetrating to the on heights of

  14. 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.

  15. 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.

  16. Implementation of Rogowski coil and Taylor discharge for ionospheric plasma chamber experiments in the Versatile Toroidal Facility (VTF)

    SciTech Connect

    Rowlands, M.J.; Riddolls, R.J.; Lee, M.C.; Dalrymple, N.; Moriarty, D.

    1996-12-31

    The VTF is a large torus used to simulate ionospheric plasmas. Currently, plasmas can be generated by electron emission from four LaB{sub 6} cathodes, spaced around the bottom of the chamber, by electron cyclotron resonance heating (ECRH) with microwaves injected radially into the chamber from a 3 kilowatt magnetron, and by a Taylor discharge apparatus. Electron beams travel in a helical path till they reach a collector plate at the top of the chamber, and produce plasma currents from 500 to 1,500 amps. Recently, a Rogowski coil has been calibrated to quantitatively measure current in the plasma. A 4.2 meter coil of approximately 5,500 turns encircles the torus vertically. As a changing current goes through the coil, a changing magnetic field is produced perpendicular to each of the coil`s turns. Each turn produces a small voltage, and the sum of all the voltages from all the turns in the coil is proportional to the change in plasma current. The voltage signal is integrated and the result is the plasma current circulating toroidally inside the chamber. Good results measuring electron beam plasma current have been obtained and will be reported on. Continuing work will include measuring alternating current from the Taylor discharge plasma and is hoped to give insight as to how to increase plasma density using the Taylor discharge device.

  17. 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 Troms 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.

  18. 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.

  19. 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.

  20. 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.

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

    SciTech Connect

    Livingston, R.C.

    1988-05-01

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

  2. 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.

  3. The Role of Ionospheric Outflow Preconditioning in Determining Storm Geoeffectiveness

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Liemohn, M. W.; Ridley, A. J.

    2012-12-01

    It is now well accepted that ionospheric outflow plays an important role in the development of the plasma sheet and ring current during geomagnetic storms. Furthermore, even during quiet times, ionospheric plasma populates the magnetospheric lobes, producing a reservoir of hydrogen and oxygen ions. When the Interplanetary Magnetic Field (IMF) turns southward, this reservoir is connected to the plasma sheet and ring current through magnetospheric convection. Hence, the conditions of the ionosphere and magnetospheric lobes leading up to magnetospheric storm onset have important implications for storm development. Despite this, there has been little research on this preconditioning; most global simulations begin just before storm onset, neglecting preconditioning altogether. This work explores the role of preconditioning in determining the geoeffectiveness of storms using a coupled global model system. A model of ionospheric outflow (the Polar Wind Outflow Model, PWOM) is two-way coupled to a global magnetohydrodynamic model (the Block-Adaptive Tree Solar wind Roe-type Upwind Scheme, BATS-R-US), which in turn drives a ring current model (the Ring current Atmosphere interactions Model, RAM). This unique setup is used to simulate an idealized storm. The model is started at many different times, from 1 hour before storm onset to 12 hours before. The effects of storm preconditioning are examined by investigating the total ionospheric plasma content in the lobes just before onset, the total ionospheric contribution in the ring current just after onset, and the effects on Dst, magnetic elevation angle at geosynchronous, and total ring current energy density. This experiment is repeated for different solar activity levels as set by F10.7 flux. Finally, a synthetic double-dip storm is constructed to see how two closely spaced storms affect each other by changing the preconditioning environment. It is found that preconditioning of the magnetospheric lobes via ionospheric outflow greatly influences the geoeffectiveness of magnetospheric storms.

  4. 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.

  5. Relationship Between Ground-based and In-situ Plasma Sheet Measurements of Convection Penetration

    NASA Astrophysics Data System (ADS)

    Sanchez, E. R.

    2009-12-01

    Shortly after the discovery of bursty plasma sheet convection, a number of observational studies have suggested a link between earthward flow bursts observed near the midnight central plasma sheet and auroral intensifications at the polar cap boundary (polar cap boundary intensifications or PBIs) and the southward propagating aurora (auroral streamers). Three different stages are identified during the southward progression of the streamers. In the first stage there is a boundary brightening followed, often within a few minutes, by the start of the propagation of aurora in the southward direction. The second stage, which usually lasts up to ten minutes, consists of the propagation of the auroral streamer into the equatorward edge of the aurora. In the third stage, the arrival of the streamer to the equatorward edge of the oval coincides with the onset of a bright spot that can last for as long as 20 minutes. Bursty convection is observed in association with streamers most commonly during steady magnetospheric convection and substorm recovery, although it is also observed in general during periods of sustained geomagnetic activity. This investigation has two objectives. The first is to determine whether reconnection is enhanced concurrently with the PBIs and whether the duration of the enhancement coincides with the southward expansion of the auroral streamers. The second objective is to determine whether the enhanced tail reconnection is associated with penetration of under-dense flux tubes into near-Earth plasma sheet. Ground-based multi-spectral optical measurements and in-situ Geotail and THEMIS measurements in the plasma sheet during extended periods of southward IMF show the causal chain whereby PBIs are indeed the optical manifestation of reconnection intensifications that power, in some cases, the penetration of fast convection into the plasma sheet. Observations show, however, that there are also intense flow bursts (~ 1000 km/s) without any clear indication of streamers and streamers without a corresponding flow burst. We discuss the consequences of these apparent discrepancies on the paradigm of penetration of under-dense flux tubes in the plasma sheet.

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

    SciTech Connect

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

    1980-09-01

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

  7. Irregularities in ionospheric plasma clouds: Their evolution and effect on radio communication

    NASA Astrophysics Data System (ADS)

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

    1980-09-01

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

  8. 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.

  9. 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.

  10. 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.

  11. Innovative development and application of models for weakly ionized ionospheric plasmas

    NASA Astrophysics Data System (ADS)

    Eccles, J. V.; Hingst, James; Armstrong, Russell

    1993-11-01

    Artificial modifications of the ionosphere through chemical releases and ionospheric heating experiments are examined with models of chemistry and transport to advance understanding of ion chemistry of the upper atmosphere. The specific releases investigated were the SF6 released of the CRRES-at-Kwajalein rocket campaign and the CO2 releases of the Red Air 1 program. Both the SF6 and CO2 releases experienced freezing or clustering of the molecules. This must be accounted for in the composition and airglow observations. In addition, HF heating effects in the E and F region were examined through modeling of energy deposition and resulting chemistry. NO(x) production in a HF ionospheric heater beam is estimated and compared with natural sources of NO(x). Global effects of HF operation are very small but the local effects can be large enough to permit observable modulation to this environment.

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

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

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

  13. 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.

  14. Observational evidence for dust-plasma interactions in the Enceladus' plume, Saturn E-ring, in Titan's ionosphere, and near comets

    NASA Astrophysics Data System (ADS)

    Wahlund, J. E.; Holmberg, M. K. G.; Engelhardt, I. A. D.; Eriksson, A. I.; Shebanits, O.; Morooka, M. W.; Farrell, W. M.; Gurnett, D. A.; Kurth, W. S.; Ye, S.

    2014-12-01

    The Cassini mission has identified dust-plasma interactions in at least three different regions in the Saturn system. These are the dusty plasma environment near Enceladus, in particular within its plume the dusty plasma environment in the Saturn inner plasma disk enveloping the E-ring the aerosol-plasma environment in Titan's deep ionosphere. It is also believed to affect the dynamics substantially in a comet coma, now studied by Rosetta. The motion of plasma is changed considerably by the presence of substantial amounts of charged dust due to the added effect of gravity and radiation pressure forces on the dust component, thereby affecting the dynamics of the magnetosphere. Conversely the Lorentz force affects the charged dust through electric and magnetic fields that normally govern the motion of the plasma. Part of the dust size distribution should be considered a component of the plasma collective ensemble. The Cassini RPWS Langmuir Probe clearly detects a difference between the electron and ion number densities in all these regions, from which the total charge density of the negatively charged dust can be estimated. Moreover, the Cassini electron spectrometer (CAPS/ELS) detects negatively charged nanometer sized particles both in Titan's ionosphere as well as in Enceladus' plume. The inferred number densities are consistent with the Langmuir probe measurements. Here, the dust absorption of electrons is so strong that an ion-dust plasma is created with few free electrons. In the case of Titan's ionosphere this triggers the formation of aerosols that then diffuse to the ground. We show here new measurements from the E-ring showing electron density depletions due to dust absorption, a dust tail region of Enceladus, and confirm the consistency between measurements of negative ions by CAPS/ELS and the Radio and Plasma Wave Science Langmuir Probe (RPWS/LP) in Titan's ionosphere. We will also show initial hints regarding dust-plasma interaction near comets from the Rosetta Langmuir probe instrument (LAP).

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Modeling the martian ionosphere

    NASA Astrophysics Data System (ADS)

    Matta, Majd Mayyasi

    The accessibility of the Martian atmosphere to spacecraft provides an opportunity to study an ionosphere that differs from our own. Yet, despite the half century of measurements made at Mars, the current state of the neutral atmosphere and its embedded plasma (ionosphere) remains largely uncharacterized. In situ measurements of the neutral and ionized constituents versus height exist only from the two Viking Landers from the 1970s. Subsequent satellite and remote sensing data offer sparse global coverage of the ionosphere. Thermal characteristics of the plasma environment are not well understood. Patchy crustal magnetic fields interact with the Martian plasma in a way that has not been fully studied. Hence, investigating the coupled compositional, thermal and crustal-field-affected properties of the ionosphere can provide insight into comparative systems at Earth and other planets, as well as to atypical processes such as the solar wind interaction with topside ionospheric plasma and associated pathways to escape. Ionospheric models are fundamental tools that advance our understanding of complex plasma systems. A pre-existing one-dimensional model of the Martian ionosphere has been upgraded to include more comprehensive chemistry and transport physics. This new BU Mars Ionosphere Model has been used to study the composition, thermal structure and dynamics of the Martian ionosphere. Specifically: the sensitivity of the abundance of ions to neutral atmospheric composition has been quantified, diurnal patterns of ion and electron temperatures have been derived self-consistently using supra-thermal electron heating rates, and the behavior of ionospheric plasma in crustal field regions was simulated by constructing a two-dimensional ionospheric model. Results from these studies were compared with measurements and show that (1) ion composition at Mars is highly sensitive to the abundance of neutral molecular and atomic hydrogen, (2) lighter ions heat up more efficiently than heavier ones and provide additional heating sources for cooler plasma, and (3) crustal field morphology affects plasma dynamics and structure at Mars in a way that is consistent with observations. Finally, model predictions of ion composition and plasma temperatures are provided for observations to be made by several instruments on board the upcoming 2013 MAVEN orbiter.

  1. 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.

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

    SciTech Connect

    Secan, J.A.

    1993-05-01

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

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. 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.

  6. Excitation of strong Langmuir turbulence in plasmas near critical density: Application to HF heating of the ionosphere

    SciTech Connect

    DuBois, D.F.; Rose H.A.; Russell, D. )

    1990-12-01

    Results are presented for an extensive study of strong Langmuir turbulence (SLT) in plasmas excited near the critical density by intense coherent radiation beams. The nominal parameters for HF heating experiments imply that the ionospheric plasma is in such a state. Long-time simulations of Zakharov's model of SLT and related theoretical arguments have led to new conclusions and insights: (1) linear parametric instabilities may play a role only during the first few milliseconds after heater turn-on in a quiescent ionosphere, but there is also the possibility of direct nucleation of cavitons in preexisting density fluctuations; (2) both possibilities lead to Langmuir collapse; (3) the turbulence is sustained by nucleation of trapped electric fields in burnt-out density-cavities from previous collapses; (4) the nucleation-collapse-burnout scenario explains several features of the observed ISR plasma line power spectra in early-time, low-duty cycle experiments and predicts new features; (5) ISR spectra obtained at early times in low-duty cycle heating experiments are consistent with the spectra of uncorrelated caviton events; (6) these spectra contain a free mode peak which is due to the radiation of free Langmuir waves by collapsing cavitons; this peak has recently been observed; (7) sharp spectral peaks observed in strong spectra in longer-time, high-duty cycle or CW heating can arise in the SLT model from spatio-temporal caviton correlations, provided overdense domains exist and a Bragg resonance condition is satisfied; (8) correlation models can explain all the sharp features including the decay line, the cascade, the narrow oscillating two-stream instability line, and the anti-Stokes line; these models do not involve parametric instabilities; (9) the characteristic structure of the ISR spectrum is maintained over a much wider range of angles relative to the geomagnetic field than is the case for weak turbulence predictions.

  7. Growth rates for modulational instabilities of radio waves in highly collisional ionospheric plasmas

    SciTech Connect

    Shukla, P.K.; Vladimirov, S.V.

    1994-03-01

    This paper looks at the nonlinear couplings which result from the transmission of powerful electromagnetic waves thru the ionosphere, which can be considered highly collisional in nature. The authors take into account ponderomotive forces, differential Joule heating, and the relativistic mass shift of the electron. They are able to derive an expression which accounts for the growth rate of the observed modulational instability which is excited.

  8. 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.

  9. 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.

  10. Reviewing the Mechanisms Underlying the Pre-reversal Enhancement of the Vertical Plasma Drift in the Low Latitude Ionosphere

    NASA Astrophysics Data System (ADS)

    Eccles, J. V.; St-Maurice, J.; Schunk, R. W.

    2013-12-01

    The evening pre-reversal enhancement (PRE) of the zonal electric field and the corresponding vertical plasma drift in the low-latitude ionosphere is an important feature in determining the structure and stability of the ionosphere. There are three competing theories of the cause of the PRE; curl free response [Eccles, 1998a and Rishbeth, 1972], off-equator Hall current divergence [Farley et al., 1986]; and equatorial electrojet current divergence [Harendel and Eccles, 1992]. We review these theories of the PRE cause in the context of field-line-integrated electrodynamics model and then examine the viability of each proposed cause using simplified electrodynamics simulations. While all three physical theories are real physical processes occurring in the evening low latitude ionosphere, we demonstrate that the PRE arises primarily from a curl-free response to the rapid temporal evolution of the vertical electric field as proposed by Eccles [1998a] in support of a short comment by Rishbeth [1972] within his paper on the F region dynamo. The curl-free effect magnitude has three components: (1) the exchange of the dominance of the E region dynamo to the F region dynamo as the E region Pedersen conductivity in conjugant hemispheres decay around sunset, (2) the acceleration of the F region zonal neutral wind as the ion-neutral drag diminishes around sunset, and (3) the apex altitude range of operation of the F region dynamo current. The maximum PRE magnitude occurs at E region sunset when the integrated E region Pedersen conductivities of both hemispheres decrease to less than the integrated F region Pedersen conductivity. The mechanism proposed by Farley et al. [1986] is examined. While the off-equator gradient of the Hall currents can affect the zonal electric field near sunset, it only provides a modest adjustment to the PRE magnitude. The Farley mechanism is limited due to the slow acceleration of the zonal neutral wind prior to E region sunset. It is also demonstrated that the magnitude of the PRE in response to the curl-free effect is affect only very slightly by conductivity conditions within the equatorial electrojet (EEJ). While the EEJ is the most important path of zonal current in the low-latitude ionosphere it is more of a passive load on the F region dynamo electromotive presence. However, the EEJ does dominate the electric field structure below the field-line integrated bottomside F region as presented by Haerendel and Eccles [1992]. These results suggest that the prediction of the PRE magnitude requires accurate knowledge of the decay of the E regions of both hemispheres and of the magnitude and acceleration of the zonal neutral wind in the F region near E region sunset. Eccles, J. V. (1998), A simple model of low-latitude electric fields, J. Geophys. Res., 103, 26,699-26,708. Farley, D. T., E. Bonelli, B.G. Fejer, and M. F. Larsen (1986), The pre-reversal enhancement of the zonal electric field in the equatorial ionosphere, J. Geophys. Res., 91, 13,723-13,728. Haerendel, G. and J. V. Eccles (1992), The Role of the equatorial electrojet in the evening ionosphere, J. Geophys. Res., 97, 1181-1192. Rishbeth, H. (1971), Polarization fields produced by winds in the equatorial F-region, Planet. Space Sci. (19) 357-369.

  11. Pre-Storm Ionospheric Oxygen Ions between the Ionosphere and the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Yau, A. W.; Howarth, A.; Peterson, W. K.; Abe, T.

    2012-04-01

    The prompt appearance of energetic O+ ions in the ring current in the growth phase of a magnetic storm raises the interesting question of the possible role of O+ ions between the ionosphere and the plasma sheet and ring current immediately preceding the main phase of a magnetic storm. We examine oxygen ion transport from the high-altitude polar ionosphere in the quiet-time periods immediately preceding a series of five large magnetic storms (Dst < -100 nT) in Solar Cycle 23, using single-particle trajectory simulations in conjunction with Akebono ion measurements and related IMF and convection electric field data. Observed low-energy O+ ions on Akebono in the quiet-time high-altitude auroral and polar cap ionosphere (7000 km) are found to have temperatures of about 0.2-0.3 eV and flow velocities of a few km/s, and a portion of the ions undergo centrifugal acceleration at higher altitudes (above about 3 Earth radii (altitude)), resulting in a low but non-negligible O+ ion flux between the ionosphere and the plasma sheet and ring current that is dependent on IMF as well as Kp: up 30% of the observed low-energy O+ ions reach the plasma sheet, and more of the ions reach the dusk than dawn, corresponding to an O+ mass source rate of ~ 0.14 kg/s and a "plasma sheet filling time" of ~6.7 hr near solar maximum, assuming a plasma sheet oxygen density of 0.1 per cc.

  12. 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.

  13. 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.

  14. Ionospheric irregularity physics modelling

    SciTech Connect

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

    1982-01-01

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

  15. Seasonal variations of the high-latitude F region for strong convection

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    A plasma convection model is combined with an ionospheric-atmospheric composition model in order to study the seasonal variations of the high-latitude F region for geomagnetic conditions leading to strong convection. In a model calculation, a field tube of plasma is followed as it moves along a convection trajectory through a moving neutral atmosphere. Altitude profiles of the ion densities are obtained by solving the appropriate continuity, momentum, and energy equations including numerous high-latitude processes. It is found that the high-latitude ionosphere exhibits a significant UT variation both during the winter and summer. In general, the electron density at high-latitudes is lower in winter than in summer. In both summer and winter, the major region of low electron density is associated with the 'main' or mid-latitude' trough.

  16. Nonlinear interaction of powerful radio waves with the plasma in the Earth's lower ionosphere

    SciTech Connect

    Shukla, P.K. ); Stenflo, L. ); Borisov, N.D. )

    1992-08-01

    The nonlinear interaction of powerful radio waves with nonresonant density fluctuations in a nonuniform weakly ionized magnetoplasma is considered. It is shown that the interaction can generate a high-frequency radio wave envelope, which generally is governed by a nonlinear Schroedinger equation. Accounting for the dependence of the attachment frequency on the radiation intensity, as well as the differential Joule heating nonlinearity, the authors derive the equations for the nonthermal electron density and temperature perturbations. The various nonlinear terms in the electron motion are compared. The implications of the investigation for the filamentation of radio waves in the lower part of the Earth's ionosphere are pointed out.

  17. 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.

  18. 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.

  19. A case study of plasma structure in the dusk sector associated with enhanced magnetospheric convection

    NASA Technical Reports Server (NTRS)

    Carpenter, D. L.; Smith, A. J.; Giles, B. L.; Chappell, C. R.; Decreau, P. M. E.

    1992-01-01

    Consideration is given to a case study based on a combination of ground whistler and satellite measurements of thermal plasma density which provides additional evidence that the abrupt western edge of the bulge region of the magnetosphere, reported earlier from whistlers, is a real phenomenon. The present data and previous MHD modeling work suggest that this distinctive feature develops during periods of steady or declining substorm activity, when dense plasma previously carried sunward under the influence of enhanced convection activity begins to rotate with the earth at angular velocities that decrease with increasing L value and becomes spirallike in form. Whistler data are used to identify a narrow dense plasma feature, separated from the main plasmasphere and extending sunward into the late afternoon sector at L values near the outer observed limits of the main plasmasphere and extending sunward into the edge of the main bulge, found by both whistler stations to be at about 1800 MLT, appeared to be quasi-stationary in sun-earth coordinates during the prevailing conditions of gradually declining geomagnetic agitation.

  20. 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.

  1. The coupling of tail fast flows to ionospheric flow signatures and their relationship to substorm onset

    NASA Astrophysics Data System (ADS)

    Zesta, E.; Lyons, L.; Angelopoulos, V.; Donovan, E.; McFadden, J.; Carlson, C.; Glassmeier, K.; Mende, S.

    2008-12-01

    Earthward convection of the tail plasma sheet is often organized in bursts of fast ion flows restricted in azimuthally narrow channels. It has been shown that Auroral Poleward Boundary Intensifications (PBIs) are often the ionospheric signature of such fast flow channels in the midtail. While PBIs can occur for all IMF orientations and solar wind conditions, they have a clear preference for southward IMF and their occurrence peaks within 1 hour after a substorm onset, with a secondary occurrence peak at 3 hrs after onset. Equatorward flow bursts have been observed in the ionosphere, that are presumably the ionospheric mapping of the tail fast flow channels. We focus on identifying such ionospheric signatures and understanding the physics of this magnetosphere-ionosphere interaction via conjunctions of the THEMIS probes with the Sondrestrom radar. From a number of such conjunctions we find that the onset of a substorm that is soon followed by a PBI has a very distinct signature in the radar data. At onset and expansion the ionospheric flow turns strictly westward. During the PBI, tail fast flows originate in the mid-tail and ionospheric flows turn equatorward. The generality and physical implications of this pattern are explored.

  2. Studies of the auroral ionosphere with the MITHRAS. Final report, October 1982-October 1985

    SciTech Connect

    Foster, J.C.

    1986-06-26

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

  3. High-latitude plasma convection during Northward IMF as derived from in-situ magnetospheric Cluster EDI measurements

    NASA Astrophysics Data System (ADS)

    Frster, M.; Haaland, S. E.; Paschmann, G.; Quinn, J. M.; Torbert, R. B.; Vaith, H.; Kletzing, C. A.

    2008-09-01

    In this study, we investigate statistical, systematic variations of the high-latitude convection cell structure during northward IMF. Using 1-min-averages of Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for six and a half years (February 2001 till July 2007), and mapping the spatially distributed measurements to a common reference plane at ionospheric level in a magnetic latitude/MLT grid, we obtained regular drift patterns according to the various IMF conditions. We focus on the particular conditions during northward IMF, where lobe cells at magnetic latitudes >80 with opposite (sunward) convection over the central polar cap are a permanent feature in addition to the main convection cells at lower latitudes. They are due to reconnection processes at the magnetopause boundary poleward of the cusp regions. Mapped EDI data have a particular good coverage within the central part of the polar cap, so that these patterns and their dependence on various solar wind conditions are well verified in a statistical sense. On average, 4-cell convection pattern are shown as regular structures during periods of nearly northward IMF with the tendency of a small shift toward negative clock angles. The positions of these high-latitude convection foci are within 79 to 85 magnetic latitude and 09:00 15:00 MLT. The MLT positions are approximately symmetric 2 h about 11:30 MLT, i.e. slightly offset from midday toward prenoon hours, while the maximum (minimum) potential of the high-latitude cells is at higher magnetic latitudes near their maximum potential difference at ?-10 to -15 clock angle for the North (South) Hemisphere. With increasing clock angle distances from ?IMFBz+, a gradual transition occurs from the 4-cell pattern via a 3-cell to the common 2-cell convection pattern, in the course of which one of the medium-scale high-latitude dayside cells diminishes and disappears while the other intensifies and merges with the opposite main cell of the same polarity to form the large "round-shaped" convection cell when approaching a well-known IMFBy-dominated configuration. Opposite scenarios with interchanged roles of the respective cells occur for the opposite turning of the clock angle and at the Southern Hemisphere. The high-latitude dayside cells become more pronounced with increasing magnitude of the IMF vector.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. Determining the electron energy distribution near the plasma potential in the earth's ionosphere

    NASA Technical Reports Server (NTRS)

    Sharp, W. E.; Hays, P. B.; Cutler, J. R.; Dobbs, M. E.

    1981-01-01

    A determination of the plasma potential using an electrostatic analyzer is described in which the potential difference between the instrument slit system and surrounding plasma is minimized. Data obtained from rocket-borne instrumentation demonstrate the viability of this technique for electron fluxes between thermal energies (about 0.5 V) and suprathermal energies (many volts).

  10. 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.

  11. Magnetosphere-ionosphere-thermosphere coupling: Effect of neutral winds on energy transfer and field-aligned current

    SciTech Connect

    Lu, G.; Richmond, A.D.; Emery, B.A.

    1995-10-01

    The assimilative mapping of ionospheric electrodynamics (AMIE) algorithm has been applied to derive the realistic time-dependent large-scale global distributions of the ionospheric convection and particle precipitation during a recent Geospace Environment Modeling (GEM) campaign period: March 28-29, 1992. The AMIE outputs are then used as the inputs of the National Center for Atmospheric Research thermosphere-ionosphere general circulation model to estimate the electrodynamic quantities in the ionosphere and thermosphere. It is found that the magnetospheric electromagnetic energy dissipated in the high-latitude ionosphere is mainly converted into Joule heating, with only a small fraction (6%) going to acceleration of thermospheric neutral winds. This study also reveals that the thermospheric winds can have significant influence on the ionospheric electrodynamics. On the average for these 2 days, the neutral winds have approximately a 28% negative effect on Joule heating and approximately a 27% negative effect on field-aligned currents. The field-aligned currents driven by the neutral wind flow in the opposite direction to those driven by the plasma convection. On the average, the global electromagnetic energy input is about 4 times larger than the particle energy input. 65 refs., 10 figs.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Linear mode conversion in inhomogeneous magnetized plasmas during ionospheric modification by HF radio waves

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    The propagation of high-frequency (HF) radio waves in an inhomogeneous magnetoactive plasma and generation of plasma waves at the resonance layer near the reflection layer of the ordinary mode are studied using one-dimensional (1-D) and two-dimensional full-wave codes. The characteristics of the mode-conversion process are investigated in linear and parabolic density profiles as the angle of incidence is varied. We present the 1-D results for the wave propagation relevant to the high-latitude heater facility at Troms and the midlatitude facility at Arecibo. For the facility at Arecibo, the 2-D wave propagation in a plasma density approximating an overdense sporadic-E patch is investigated to determine the localized regions of amplified intensity, where plasma waves can facilitate acceleration of fast energetic electrons, resulting in observed enhanced airglow.

  17. 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.

  18. Observation of wake-induced plasma waves around an ionospheric sounding rocket

    NASA Astrophysics Data System (ADS)

    Endo, K.; Kumamoto, A.; Katoh, Y.

    2015-06-01

    Plasma waves generated around the plasma wake of a supersonically moving rocket are studied using data from an impedance probe and a wave receiver installed on the sounding rocket S-520-26. These instruments were used to measure the electron number density and plasma waves at 260 ms intervals, which allows four to five measurements per rotation. During the flight of the S-520-26, three types of plasma waves were observed: short-wavelength electrostatic waves such as electrostatic electron cyclotron harmonic waves, upper hybrid resonance mode waves, and whistler mode waves, assuming that the observed waves are produced in the near wake of the rocket. The wave generation mechanisms are discussed by calculating the linear growth rates of electrostatic waves; positive growth rates are obtained with the assumption of an anisotropic electron distribution function having a beam component or temperature anisotropy. We revealed the spatial distribution of the wave activity around the rocket and its relationship with the wake structure by analysis of the spin-phase dependence of the waves and the observed electron number density. The spin-phase dependence suggests that there are localized hot plasmas around the wake structure that can induce various types of plasma instability.

  19. 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.

  20. 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.

  1. On the generation of a broad downshifted spectrum of HF wave enhanced plasma lines in the ionospheric heating experiments

    NASA Astrophysics Data System (ADS)

    Kuo, S. P.; Lee, M. C.

    Generation of a broad downshifted spectrum of HF wave enhanced plasma Lines (HFPLs) in ionospheric heating experiments is explored. Langmuir waves are first excited within a cone around the geomagnetic field by the HF wave, in the region near its reflection height, through the oscillating two stream instability (OTSI). These Langmuir waves then cascade through a secondary parametric instability, whereby an obliquely propagating Langmuir pump wave decays into an obliquely propagating Langmuir sideband and a lower hybrid decay mode, which propagates in a direction perpendicular to the Langmuir pump wave. The excited Langmuir sidebands have a broad downshifted frequency spectrum and large propagation angles. Their propagation angles are further widened via the filamentation instability or scattering off short-scale field-aligned density irregularities. Thus they become detectable by backscatter radars as HFPLs with a broad downshifted frequency spectrum. The results of our analysis show that it requires HF field amplitude of 3.6 V/m to cascade the OTSI-excited Langmuir waves, for example, 8 times to produce a downshifted spectral width of 50 KHz in the Arecibo heating experiments.

  2. Tail and Ionospheric Signatures of Tail Fast Flows Associated with PBIs and with Substorms

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Zesta, E.; Lyons, L.; Angelopoulos, V.; Donovan, E.; McFadden, J.; Carlson, C.; Glassmeier, K.; Mende, S.

    2009-05-01

    Earthward convection of the tail plasma sheet is often organized in bursts of fast ion flows restricted in azimuthally narrow channels. It has been shown that Auroral Poleward Boundary Intensifications (PBIs) are often the ionospheric signature of such fast flow channels in the midtail. Equatorward flow bursts have been observed in the ionosphere, and have been shown to be the ionospheric mapping of the tail fast flow channels in few case studies. We focus on identifying such ionospheric signatures and understanding the physics of this magnetosphere-ionosphere interaction via conjunctions of the THEMIS probes with the Sondrestrom radar. We find fundamental differences between the tail fast flows that are associated with substorm onsets and those associated with PBIs, as well as between their respective ionospheric flow signatures. The tail fast flows that produce PBIs are observed in the midtail. They do not typically penetrate to the inner magnetosphere and they are accompanied by plasma sheet expansion signatures in the mid tail. No dipolarization signatures are observed in the inner magnetosphere. The ionospheric signatures associated with such tail flows are PBI- type aurora and substantially enhanced equatorward flows. Tail fast flows that are associated with substorm onsets are typically observed only by the inner magnetosphere probes, only occasionally being seen also in the midtail. Clear dipolarizations are seen with such flows in the inner magnetosphere but not in the midtail. The ionospheric flow associated with such tail fast flows is far distinct, enhanced westward flows being occasionally seen at the higher latitude part of the Sondrestrom field of view with enhanced eastward flows observed at the lower latitudes. Enhanced equatorward flows are not seen.

  3. 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.

  4. The solar cycle variations of plasma parameters and their correlations at topside ionosphere from DEMETER during 2005-2010

    NASA Astrophysics Data System (ADS)

    Zhang, Xuemin; Shen, Xuhui; Yuan, Guiping

    2015-10-01

    Based on the IAP (Instrument d'Analyse du Plasma) observing data onboard DEMETER satellite, the solar cycle variations in ion density (Ni), ion composition [O+, H+, He+] and ion temperature (Ti) were analyzed respectively in local daytime 10:30 and nighttime 22:30 during 2005-2010 during the 23rd/24th solar cycles, which would greatly contribute to the research of the topside ionospheric physics during this extremely low solar minimum. Based on analyzing the solar cycle variations of these plasma parameters, it was found that longitude-averaged Ni, [O+] and daytime Ti presented positive correlation with solar flux, while [H+], nighttime Ti and [He+] varied negatively to reach their maxima at the solar minimum. Furthermore, [O+], as the main composition at the altitude of DEMETER of 660 km, showed typical seasonal variation and close relationship with sub-solar dynamics. Daytime [He+] was the most complex component, showing negative variation with solar activity at low latitudes over Southern Hemisphere and positive correlation at middle latitudes over Northern Hemisphere. The correlation of Ni and Ti in local daytime was dependent on season over two hemispheres, and the results illustrated negative correlation at low latitudes, and positive correlation at middle latitudes especially over Southern Hemisphere in solstitial seasons. While [H+] presented anti-correlation, especially the peak values with Ti valleys at 0-20N in each year, which all might be related to the thermal diffusion and relative drift among different ions. Furthermore, the asymmetrical features of Ni over two hemispheres in solar minimum were widely revealed at different longitude sectors, latitudes and local times, which might be explained by the concentration of neutral oxygen, neutral winds, and also the lower atmospheric dynamics.

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

    SciTech Connect

    Secan, J.A.

    1991-05-15

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

  6. Observations of Substorms from the Auroral Ionosphere to the Distant Plasma Sheet

    NASA Technical Reports Server (NTRS)

    Parks, G.; Brittnacher, M.; Chen, L.; Chua, D.; Elsen, R.; Fillingim, M.; McCarthy, M.; Germany, G.; Spann, J.

    1998-01-01

    We have been studying how substorms work by examining the global polar Ultraviolet Imager (UVI) images in correlation with observations from the ground, interplanetary space and the geomagnetic tail between 10-20 earth radii. One of the objectives of our study is to better understand the connection among many complex phenomena going on close to Earth and those in the distant plasma sheet. We have studied, for example, how the aurora[ and polar cap boundaries at different local times behave in relation to variations observed in the solar wind and plasma sheet during substorms. Preliminary results indicate that the polar cap and auroral oval boundaries expand and contract in a complicated but systematic way. These variations are correlated to solar wind parameters, and thinning and recovery phenomena in the plasma sheet. These results will be presented and interpreted in terms of directly driven and/or unloading substorm processes.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  8. 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.

  9. 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.

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

    NASA Technical Reports Server (NTRS)

    Venkatraman, Sarita; Heelis, Rod

    1999-01-01

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

  11. Equivalent circuit simulation of cylindrical monopole impedance measurements in ionospheric electron plasma

    NASA Astrophysics Data System (ADS)

    Kiraga, A.

    Several common problems occur in measurement techniques and interpretation of plasma natural emissions and impedance data. Antenna characteristics are of prime importance in equivalent circuit analysis. Spacecraft - plasma interaction contributes to variability of equivalent circuit impedances and e.m.f. components and imposes constrains on usefulness of experimental data. In order to have independent, built in estimate of local plasma frequency and to get deeper insight into properties of equivalent circuit for wave diagnostics, impedance measurement was integrated with radio receivers on the ACTIVE, APEX and CORONAS satellites. Impedance measurements of 7.5m long monopole were performed in frequency range .1-10MHz with the frequency step of 50kHz, in voltage divider configuration. Due to high inclination of 82.5deg and altitude range of 500-3000km, data from very different plasmas were collected. Data can be split into quasi normal, disturbed and very disturbed measurements. Equivalent circuit structure evolved in attempt to m tcha even very disturbed measurements. For quasi normal measurements, satisfactory matching is obtained with computed gyrofrequency fc and fitted plasma frequency fn, stray capacitance Cs and capacitance Cv of phenomenological vacuum sheath. With Balmain formula for monopole impedance in cold magnetoplasma, two basic spectral structures are explained. For sufficiently magnetized plasma (roughly fn/fc<2 if Cs=20pF), circuit parallel resonance frequency Fr falls into upper hybrid band (max(fn,fc),fu), resonance amplitude is reduced by high antenna resistance and horn like absolute maximum points fu. For values of fn/fc ratio, greater then critical, Fr is less than fn and broad absolute maximum at Fr follows from low antenna resistance. Further increase of fn/fc results in increasing lag of Fr behind fn. Critical rati o fn/fc increases with decreasing stray capacitance Cs. It follows from data analysis that stray capacitance may change in flight, at least due to attitude changes, so mentioned basic structures may be relevant in stray compensated bridge configuration. It is found that strongly disturbed measurements are related to activation of fast diodes, designed for input protection. Injections of charged particle beams saturated instrument. On line telemetry transmission interfered directly by receipted VHF fields and indirectly by particle acceleration leading to differential charging and direct current flow. In dense equatorial plasma, very peculiar evolution of base voltage spectra is linked to differential charging and intense direct current flow of thermal electrons. Deep, quasi periodic modulations or irregular excursions on time scales much shorter than sweep period are indicative of differential charging by ambient, energetic minor populations. Presented data and simulations address challenges in instrument design, monitoring and onboard data processing.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Radar interferometry: A new technique for studying plasma turbulence in the ionosphere

    SciTech Connect

    Farley, D.T.; Ierkic, H.M.; Fejer, B.G.

    1981-03-01

    A new radar interferometer technique has been developed and used successfully at the Jicamarca Radio Observatory in Peru to study the strong nighttime plasma turbulence in the equatorial electrojet. The technique represents a major step forward in radar probing of turbulent irregularities such as (but not limited to) those in the electrojet. In many situations it provides far more information than previous Doppler measurements. We form the cross spectrum of the backscattered signals received from approximately overhead on two antennas, separated in this case along an east-west baseline, as well as the individual power spectra. From the phase of the cross spectrum at different Doppler frequencies we can determine the individual positions of plasma wave packets propagating vertically with different velocities, and we find, for example, that oppositely propagating waves always come from distinctly separated regions. The data allow us to study the eddy structure within the electrojet in far more detail than hitherto possible, and by using the irregularity patches as tracers and following their east-west motion, we can obtain a vertical profile of drift velocity. Our first observations of this sort have shown that at night the vertical Doppler velocity at times may substantially exceed the mean horizontal velocity of the patch and the small horizontal velocity near the top and bottom of the layer may actually be westward when the main motion is eastward.

  19. Radar soundings of the ionosphere of Mars.

    PubMed

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

    2005-12-23

    We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types of ionospheric echoes are observed, ranging from vertical echoes caused by specular reflection from the horizontally stratified ionosphere to a wide variety of oblique and diffuse echoes. The oblique echoes are believed to arise mainly from ionospheric structures associated with the complex crustal magnetic fields of Mars. Echoes at the electron plasma frequency and the cyclotron period also provide measurements of the local electron density and magnetic field strength. PMID:16319123

  20. Plasma instabilities in the high- and low-latitude E region induced by high-power radio waves. Interim report

    SciTech Connect

    Chaturvedi, P.K.; Ossakow, S.L.

    1990-09-14

    The effect of a high frequency (HF) powerful pump wave on high and low latitude E-region low frequency plasma instabilities is theoretically considered. The growth rates and threshold criteria are calculated for the electrojet associated (Farley-Buneman, gradient-drift) and higher altitude high latitude parallel-current associated (ion-acoustic, ion cyclotron, current convective) instabilities. The results are discussed in the context of present ionospheric modification (heating) experiments, for the high and low latitude ionosphere.

  1. Field-aligned currents and ionospheric electric fields in the vicinity of the dayside polar cleft: observations and simulations

    SciTech Connect

    Clauer, C.R.

    1985-10-01

    Correlative observations of solar-wind plasma parameters and IMF (Interplanetary Magnetic Field) from the IMP-8 satellites were studied. These data indicate that the dayside high-latitude ionospheric electric field, which drives the observed F-region plasma convection, responds within about 14 minutes to IMF variations at the magnetopause. There is also an indication that IMF fluctuations of 10 minutes or less do not produce changes in the ionospheric electric-field configuration. It has also been found that use of a very simple model of the polar cleft currents driven by solar wind electric fields is able to explain much of the temporal variations in the ionospheric plasma convection pattern observed using the Sondrestrom radar. Several areas of disagreement will require refinement of the simple model. For example, observations during intervals of northward IMF are not consistent with the simulations. Also, occasionally the convection equatorward of the cleft currents in the model is inconsistently with observations, particularly near local noon. Which suggests that the Region 1 and Region 2 currents near noon may not be modeled properly.

  2. 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.

  3. Tail and ionospheric signatures of tail fast flows associated with PBIs and with substorms

    NASA Astrophysics Data System (ADS)

    Shi, Yong; Zesta, Eftyhia; Lyons, Larry; Angelopoulos, Vassilis; Donovan, Eric; McFadden, James; Carlson, Charles; Glassmeier, K.-H.; Mende, Stephen

    Earthward convection of the tail plasma sheet is often organized in bursts of fast ion flows restricted in azimuthally narrow channels. It has been shown that Auroral Poleward Boundary Intensifications (PBIs) are often the ionospheric signature of such fast flow channels in the midtail. Equatorward flow bursts have been observed in the ionosphere, and have been shown to be the ionospheric mapping of the tail fast flow channels in 2 case studies. We focus on identifying such ionospheric signatures and understanding the physics of this magnetosphere-ionosphere interaction via conjunctions of the THEMIS probes with the Sondrestrom radar. We find fundamental differences between the tail fast flows that are associated with substorm onsets and those associated with PBIs, as well as between their respective ionospheric flow signatures. The tail fast flows that produce PBIs are observed in the midtail. They do not typically penetrate to the inner magnetosphere and they are accompanied by dipolarizations in the mid tail. No dipolarization signatures are observed in the inner magnetosphere. The ionospheric signatures associated with such tail flows are PBI-type aurora and substantially enhanced equatorward flows around midnight. Tail fast flows that are associated with substorm onsets are typically observed only by the inner magnetosphere probes, only occasionally being seen in the midtail. Clear dipolarizations are seen with such flows in the inner magnetosphere but not in the midtail. The ionospheric flow associated with such tail fast flows shows a clear change after the substorm onset. We find that before onset there is generally enhanced eastward flow. Just after onset, the flow suddenly changes to westward with either similar magnitude as the preceded eastward flow or much weaker magnitude. Enhanced equatorward flows are not seen.

  4. Modifying the ionosphere with intense radio waves.

    PubMed

    Utlaut, W F; Cohen, R

    1971-10-15

    The ionospheric modification experiments provide an opportunity to better understand the aeronomy of the natural ionosphere and also afford the control of a naturally occurring plasma, which will make possible further progress in plasma physics. The ionospheric modification by powerful radio waves is analogous to studies of laser and microwave heating of laboratory plasmas (20). " Anomalous" reflectivity effects similar to the observed ionospheric attenuation have already been noted in plasmas modulated by microwaves, and anomalous heating may have been observed in plasmas irradiated by lasers. Contacts have now been established between the workers in these diverse areas, which span a wide range of the electromagnetic spectrum. Perhaps ionospheric modification will also be a valuable technique in radio communications. PMID:17778050

  5. 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.

  6. 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.

  7. 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

  8. Coordinated ESR-Reimei observations of the cusp ionosphere

    NASA Astrophysics Data System (ADS)

    Pitout, F.; Ogawa, Y.; Ebihara, Y.; Asamura, K.; Hirahara, M.; Seki, K.

    2010-12-01

    The polar cusp, being the region where the magnetosheath plasma has a direct access to the magnetosphere and the polar ionosphere, is an interesting region to study, not only to understand how the coupling between the solar wind and the magnetosphere works, but also because at its footprint, interesting ionospheric phenomena occur: complex local electrodynamics, particle heating and outflow, etc. To study those phenomena, we have selected a few Reimei satellite overflights of the EISCAT Svalbard Radar (ESR) in the cusp region. These conjunctions allow us to directly compare precipitating magnetosheath particles and their effects on the dayside polar ionosphere. We present preliminary results of two of those conjunctions. The first case is characterized by an unusually strong zonal convection speed measured by the ESR at 08:25 UT on September 28, 2007. This strong plasma flow is believed to increase the ion temperature through frictional heating with the neutrals and drive ion outflow. However, we do not allays see very high ion temperature in our case, suggesting that Joule heating is not the unique source of ion outflow. In the second case around 08:11 UT on October 18, 2007, the conjunction occurs when the ESR is at the equatorward boundary of the cusp. Yet, the soft-electron precipitation is rather weak and as well as the electron temperature measured by the ESR. An interesting feature is that the particle sensor onboard Reimei observes a discontinuous cusp that we explain by the changes in the IMF orientation (given by Themis).

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    Park, J.; Lhr, 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.

  11. 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 2? 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

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

    SciTech Connect

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

    1993-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  18. 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.

  19. A Review of Ionospheric Scintillation Models

    NASA Astrophysics Data System (ADS)

    Priyadarshi, S.

    2015-03-01

    This is a general review of the existing climatological models of ionospheric radio scintillation for high and equatorial latitudes. Trans-ionospheric communication of radio waves from transmitter to user is affected by the ionosphere which is highly variable and dynamic in both time and space. Scintillation is the term given to irregular amplitude and phase fluctuations of the received signals and related to the electron density irregularities in the ionosphere. Key sources of ionospheric irregularities are plasma instabilities; every irregularities model is based on the theory of radio wave propagation in random media. It is important to understand scintillation phenomena and the approach of different theories. Therefore, we have briefly discussed the theories that are used to interpret ionospheric scintillation data. The global morphology of ionospheric scintillation is also discussed briefly. The most important (in our opinion) analytical and physical models of scintillation are reviewed here.

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  1. 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.

  2. 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 Earths 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 ?c=10. The difference between the maximum mapped convection and the maximum velocity measured along the satellite track (?v) is introduced to evaluate goodness-of-fit. For the examples presented in this paper, we show that a threshold value of ?v=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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1996-10-01

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

  8. 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.

  9. Diurnal transport effects on the F-region plasma at Chatanika under quiet and disturbed conditions

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    High latitude ionospheric model predictions are compared with the diurnal variations of plasma convection velocities and electron densities observed at Chatanika, Alaska, on geomagnetically quiet and disturbed days near equinox. Since the time-dependent variation of the magnetospheric electric field was not known, plasma drift velocities and ion densities are calculated for two different convection-precipitation models, each of which corresponds to a different level of magnetic activity. Model calculations for the magnetically quiet day produced plasma drift velocities and electron densities that were in good agreement, both qualitatively and quantitatively, with the measurements. The two models have demonstrated the relative sensitivity of the high latitude ionosphere to different combinations of magnetospheric convection and induced vertical drifts associated with thermospheric winds.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    SciTech Connect

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

    1987-05-07

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

  15. Plasma transport in the magnetotail lobes

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

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

  16. 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.

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

    SciTech Connect

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

    1993-11-01

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

  18. 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.

  19. Microwave heating of the lower ionosphere

    NASA Technical Reports Server (NTRS)

    Meltz, G.; Nighan, W. L.

    1980-01-01

    Changes in the properties of the lower ionosphere due to ohmic heating of the plasma by the solar power satellite (SPS) microwave power beam are considered. The development of a predictive model of the underdense interaction of an electromagnetic beam and the lower ionosphere is described. The extent to which the Platteville and Arecibo experiments simulate SPS conditions is considered.

  20. 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 4?/?3.4 class solar flare. To perform the study we utilize the ground data from North-East Asian ionospheric and magnetic observatories (60-72N, 88-152E) 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 (66.8N, 123.3E), and a drastic decrease in the F2 layer critical frequency (foF2) up to 54% of the quite one over subauroral Yakutsk station (62N, 129.7E). 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.

  1. Plasma structuring in the polar cap

    SciTech Connect

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

    1990-01-01

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

  2. Physical Processes for Driving Ionospheric Outflows in Global Simulations

    NASA Technical Reports Server (NTRS)

    Moore, Thomas Earle; Strangeway, Robert J.

    2009-01-01

    We review and assess the importance of processes thought to drive ionospheric outflows, linking them as appropriate to the solar wind and interplanetary magnetic field, and to the spatial and temporal distribution of their magnetospheric internal responses. These begin with the diffuse effects of photoionization and thermal equilibrium of the ionospheric topside, enhancing Jeans' escape, with ambipolar diffusion and acceleration. Auroral outflows begin with dayside reconnexion and resultant field-aligned currents and driven convection. These produce plasmaspheric plumes, collisional heating and wave-particle interactions, centrifugal acceleration, and auroral acceleration by parallel electric fields, including enhanced ambipolar fields from electron heating by precipitating particles. Observations and simulations show that solar wind energy dissipation into the atmosphere is concentrated by the geomagnetic field into auroral regions with an amplification factor of 10-100, enhancing heavy species plasma and gas escape from gravity, and providing more current carrying capacity. Internal plasmas thus enable electromagnetic driving via coupling to the plasma, neutral gas and by extension, the entire body " We assess the Importance of each of these processes in terms of local escape flux production as well as global outflow, and suggest methods for their implementation within multispecies global simulation codes. We complete 'he survey with an assessment of outstanding obstacles to this objective.

  3. Localized electron density enhancements in the high-altitude polar ionosphere and their relationships with storm-enhanced density (SED) plumes and polar tongues of ionization (TOI)

    NASA Astrophysics Data System (ADS)

    Kitanoya, Y.; Abe, T.; Yau, A. W.; Hori, T.; Nishitani, N.

    2011-02-01

    Events of localized electron density increase in the high-altitude (>3000 km) polar ionosphere are occasionally identified by the thermal plasma instruments on the Akebono satellite. In this paper, we investigate the vertical density structure in one of such events in detail using simultaneous observations by the Akebono and DMSP F15 satellites, the SuperDARN radars, and a network of ground Global Positioning System (GPS) receivers, and the statistical characteristics of a large number (>10 000) of such events using Akebono data over half of an 11-year solar cycle. At Akebono altitude, the parallel drift velocity is remarkably low and the O+ ion composition ratio remarkably high, inside the high plasma-density regions at high altitude. Detailed comparisons between Akebono, DMSP ion velocity and density, and GPS total electron content (TEC) data suggest that the localized plasma density increase observed at high altitude on Akebono was likely connected with the polar tongue of ionization (TOI) and/or storm enhanced density (SED) plume observed in the F-region ionosphere. Together with the SuperDARN plasma convection map these data suggest that the TOI/SED plume penetrated into the polar cap due to anti-sunward convection and the plume existed in the same convection channel as the dense plasma at high altitude; in other words, the two were probably connected to each other by the convecting magnetic field lines. The observed features are consistent with the observed high-density plasma being transported from the mid-latitude ionosphere or plasmasphere and unlikely a part of the polar wind population.

  4. Historical overview of HF ionospheric modification research

    SciTech Connect

    Gordon, W.E.; Duncan, L.M.

    1990-10-01

    Radio waves have inadvertently modified the Earth's ionosphere 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 effects 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 modification 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. Here we present a brief overview of these processes and phenomena, 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.

  5. Ion Escape from the Ionosphere of Titan

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  6. Effects of Convection Electric Fields on Modeled Plasmaspheric Densities and ccc Temperatures

    NASA Technical Reports Server (NTRS)

    Comfort, Richard H.; Richards, Phil G.; Liao, Jin-Hua; Craven, Paul D.

    1998-01-01

    This paper examines the effects of convection electric fields on plasmaspheric H+, O+, He+, and N+ densities and electron and ion temperatures. These effects are studied with the aid of the Field Line Interhemispheric Plasma (FLIP) model, which has recently been extended to include the effects of ExB drifts. The FLIP model solves the continuity and momentum equations for the major ion species as well as the energy equations for ions and electrons along entire drifting flux tubes from 100 km altitude in the northern hemisphere to 100 km altitude in the southern hemisphere. Electron heating in the ionosphere and plasmasphere is provided by the solution of two-stream equations for photoelectrons. The dawn-dusk electric field imposed by the solar wind causes changes in plasmaspheric density and temperature as the plasma drifts onto flux tubes having different volumes. In an idealized convection model, outward drifts in the afternoon cause decreases in the plasmasphere density and temperature while inward drifts in the evening cause increases in plasmasphere density and temperature. In this paper we examine the effects of convection electric fields on the rate of refilling of flux tubes and investigate the hypothesis that convection electric fields are responsible for the unusually high evening electron temperatures and the post-midnight density maxima often observed in the winter ionosphere above Millstone Hill.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  8. 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.

  9. Magnetosheath-ionspheric plasma interactions in the cusp/cleft. 2: Mesoscale particle simulations

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Menietti, J. D.; Lin, C. S.

    1993-01-01

    Ionospheric plasma flowing out from the cusp can be an important source of plasma to the magnetosphere. One source of free energy that can drive this outflow is the injection of magnetosheath plasma into the cusp. Two-dimensional (three velocity) mesoscale particle simulations are used to investigate the particle dynamics in the cusp during southward interplanetary magnetic field. This mesoscale model self-consistently incorporates (1) global influences such as the convection of plasma across the cusp, the action of the mirror force, and the injection of the magnetosheath plasma, and (2) wave-particle interactions which produce the actual coupling between the magnetosheath and ionospheric plasmas. It is shown that, because the thermal speed of the electrons is higher than the bulk motion of the magnetosheath plasma, an upward current is formed on the equatorward edge of the injection region with return currents on either side. However, the poleward return currents are the stronger due to the convection and mirroring of many of the magnetosheath electrons. The electron distribution in this latter region evolves from upward directed streams to single-sided loss cones or possibly electron conics. The ion distribution also shows a variety of distinct features that are produced by spatial and/or temporal effects associated with varying convection patterns and wave-particle interactions. On the equatorward edge the distribution has a downflowing magnetosheath component and an upflowing cold ionospheric component due to continuous convection of ionospheric plasma into the region. In the center of the magnetosheath region, heating from the development of an ion-ion streaming instability causes the suppression of the cold ionospheric component and the formation of downward ionospheric streams. Further poleward there is velocity filtering of ions with low pitch angles, so that the magnetosheath ions develop a ring-beam distribution and the ensuing wave instabilities generate downward ionospheric conics. These downward ionospheric components are eventually turned by the mirror force, leading to the production of upward conics at elevated energies throughout the region.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    SciTech Connect

    Intriligator, D.S. )

    1989-02-01

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

  3. Heater Beam Angle Effect on Stimulated Electromagnetic Emission in a Magnetized Ionospheric Plasma using the HAARP transmitter

    NASA Astrophysics Data System (ADS)

    Fu, H.; Scales, W.; Bernhardt, P. A.

    2011-12-01

    The HAARP 3.6MW HF transmitter can excite a broad spectrum of Stimulated Electromagnetic Emission (SEE) lines, which can be utilized as a tool to provide useful diagnostics during modification of the ionosphere. The HAARP transmitter beam angle has been confirmed as an important factor for exciting the ion acoustic (IA) and electrostatic ion cyclotron wave (EIC) spectrum lines by the process called Magnetized Stimulated Brillouin Scatter (MSBS) for SEE generation. Such SEE lines can be used for electron temperature and ion composition diagnostic purposes. The experiment conducted at 2010 HAARP summer school aimed to look more thoroughly at a broader range of heater beam angle effects on low frequency SEE emission lines generated by MSBS. The experimental results show that two stronger IA emission lines and two EIC spectrum emission lines were observed by the O-mode excitation near the reflection and upper hybrid resonance region in the F layer of the ionosphere. With tilting angles far away from magnetic zenith, there exists a critical heater power beam angle, where two EIC spectrum lines appear in the lower SEE spectrum. The newly observed EIC line is considered to originate from the upper hybrid resonance region. The experiment conducted at 2011 HAARP research campaign aims to excite stronger EIC emission lines by the MSBS process to confirm theoretical prediction. In addition, the MSBS process impacted by the heater beam angle is also investigated near the 2nd electron gyro harmonic. Observations show possibly unobserved SEE spectrum lines by other process, which could be related to the MSBS process. These may be due to strong electron temperature enhancement. The possibility will be discussed in more detail during the presentation.

  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. A mathematical model of the middle and high latitude ionosphere

    NASA Technical Reports Server (NTRS)

    Schunk, R. W.

    1988-01-01

    A time-dependent three-dimensional model of the middle and high latitude ionosphere is described. The density distributions of six ion species NO(+), O(2+), N(2+), O(+), N(+), He(+), and the electron and ion temperatures are obtained from a numerical solution of the appropriate continuity, momentum, and energy equations. The equations are solved as a function of height for an inclined magnetic field at E and F region altitudes. The three-dimensional nature of the model is obtained by following flux tubes of plasma as they convect or corotate through a moving neutral atmosphere. The model takes account of field-aligned diffusion, cross-field electrodynamic drifts, thermospheric winds, polar wind escape, energy-dependent chemical reactions, neutral composition changes, ion production due to solar EUV radiation and auroral precipitation, thermal conduction, diffusion-thermal heat flow and local heating and cooling processes. The model also takes account of the offset between the geomagnetic and geographic poles.

  6. Electrostatic reconnection in the ionosphere

    NASA Astrophysics Data System (ADS)

    Huba, J. D.; Wu, T.-W.; Makela, J. J.

    2015-03-01

    Postsunset equatorial plasma bubble merging is examined using the National Research Laboratory code SAMI3/equatorial spread F. It is found that bubbles merge through an "electrostatic reconnection" process. As multiple bubbles develop, the electrostatic potential associated with one bubble can connect with that of a neighboring bubble: this provides a pathway for the low-density plasma in one bubble to flow into the adjoining bubble and merge with it. Additionally, high-speed plasma channels (approximately greater than hundreds of meters per second) can develop during the merging process. Optical data is presented of equatorial plasma bubble evolution that suggests bubble merging occurs in the nighttime equatorial ionosphere.

  7. 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.

  8. 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.

  9. 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 (500?0-1 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.

  10. 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.

    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.

  11. 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.

  12. 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.

  13. Effect of external plasma flows on the interaction between turbulence and convective cells

    NASA Astrophysics Data System (ADS)

    Uzawa, Ken; Li, Jiquan

    2005-10-01

    It is widely recognized that large scale structures, such as zonal flows, streamers and also long wavelength Kelvin-Helmholtz modes are nonlinearly generated from maternal turbulence through modulational instability process and play a crucial role in regulating the transport in tokamaks. In order to control the transport, it is desirable to control such structures and/or modulational process. One of control parameters may be mean flow which intrinsically exists in tokamak plasmas. Besides the direct influence on the transport through vortex decorrelation, the mean flow may indirectly change the zonal flow generation by acting on the modulational process itself. In this work, we theoretically investigate the characteristics of zonal flow generation due to the electron temperature gradient (ETG) turbulence in the presence of long wavelength ITG driven zonal flow. This was done by extending our previous modulational analyses[1]. We have numerically analyzed the influence of mean flow on zonal flow generation. The main result is that the zonal flow generation is suppressed by the presence of the mean flow. [1]J. Li, Y. Kishimoto, Physics of Plasmas, 9, 1241 (2002)

  14. 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.

  15. 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.

  16. Ionospheric irregularity physics modelling. Memorandum report

    SciTech Connect

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

    1982-02-09

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

  17. By-controlled convection and field-aligned currents near midnight auroral oval for northward interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Taguchi, S.; Sugiura, M.; Iyemori, T.; Winningham, J. D.; Slavin, J. A.

    1994-01-01

    Using the Dynamics Explorer (DE) 2 magnetic and electric field and plasma data, B(sub y)- controlled convection and field-aligned currents in the midnight sector for northward interplanetary magnetic field (IMF) are examined. The results of an analysis of the electric field data show that when IMF is stable and when its magnitude is large, a coherent B(sub y)-controlled convection exists near the midnight auroral oval in the ionosphere having adequate conductivities. When B(sub y) is negative, the convection consists of a westward (eastward) plasma flow at the lower latitudes and an eastward (westward) plasma flow at the higher latitudes in the midnight sector in the northern (southern) ionosphere. When B(sub y) is positive, the flow directions are reversed. The distribution of the field-aligned currents associated with the B(sub y)-controlled convection, in most cases, shows a three-sheet structure. In accordance with the convection the directions of the three sheets are dependent on the sign of B(sub y). The location of disappearance of the precipitating intense electrons having energies of a few keV is close to the convection reversal surface. However, the more detailed relationship between the electron precipitation boundary and the convection reversal surface depends on the case. In some cases the precipitating electrons extend beyond the convection reversal surface, and in others the poleward boundary terminates at a latitude lower than the reversal surface. Previous studies suggest that the poleward boundary of the electrons having energies of a few keV is not necessarily coincident with an open/closed bounary. Thus the open/closed boundary may be at a latitude higher than the poleward boundary of the electron precipitation, or it may be at a latitude lower than the poleward boundary of the electron precipitation. We discuss relationships between the open/closed boundary and the convection reversal surface. When as a possible choice we adopt a view that the open/closed boundary agrees with the convection reversal surface, we can explain qualitatively the configuration of the B(sub y)-controlled convection on the open and close field line regions by proposing a mapping modified in accordance with IMF B(sub y).

  18. Ionospheric hot spot at high latitudes

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    Schunk and Raitt (1980) and Sojka et al. (1981) have developed a model of the convecting high-latitude ionosphere in order to determine the extent to which various chemical and transport processes affect the ion composition and electron density at F-region altitudes. The numerical model produces time-dependent, three-dimensional ion density distributions for the ions NO(+), O2(+), N2(+), O(+), N(+), and He(+). Recently, the high-latitude ionospheric model has been improved by including thermal conduction and diffusion-thermal heat flow terms. Schunk and Sojka (1982) have studied the ion temperature variations in the daytime high-latitude F-region. In the present study, a time-dependent three-dimensional ion temperature distribution is obtained for the high-latitude ionosphere for an asymmetric convection electric field pattern with enhanced flow in the dusk sector of the polar region. It is shown that such a convection pattern produces a hot spot in the ion temperature distribution which coincides with the location of the strong convection cell.

  19. 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.

  20. 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.

  1. Ionospheric Flow Shear Associated with Poleward Boundary Intensification (PBI)

    NASA Astrophysics Data System (ADS)

    Shi, Y.; Zesta, E.; Lyons, L. R.; Boudouridis, A.; Kim, H.

    2010-12-01

    In this study, we investigate the relation of PBIs to the variation of ionospheric convection flows by overlaying flow observations from the SuperDARN radar and concurrent auroral images from the IMAGE satellite. We find that the aurora of most PBIs has a clear ionospheric flow shear around the auroral form and occurring simultatneously with the PBI onset. The flow shear is in the south/east to north/west direction, along the direction of the auroral form, with the south/east flow occurring at the poleward side of the PBI and the south/west flow at the bottom side of the PBI. The PBI auroral arcs are found to be near the center of the shear. The magnitude of the flow generally enhances on either side or on both sides of PBI. Corresponding DMSP observations indicate the existence upward field-aligned current (FAC) in the region of the aurora arc and downward FACs poleward of as well as equatorward of the auroral arc. This is consistent with the FAC current structure associated with the plasma sheet bubble model. It also fits the spatial distribution of large-scale region 1 and region 2 FAC in the premidnight sector. We also find that the PBI aurora occurs near the open-closed field line boundary but on closed field lines, although flow enhancement does appear on open field lines. In situ observations from Geotail for fortuitous conjunctions confirm the association of PBIs and the simultaneous ionospheric flow shear with midtail fast flows.

  2. 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.

  3. 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 Alfvn 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.

  4. Exploring Sources of Magnetospheric Plasma Using BATS-R-US

    NASA Astrophysics Data System (ADS)

    Welling, D. T.; Ridley, A. J.

    2009-05-01

    After decades of research, there is still no true consensus concerning the source or entry mechanism for plasma sheet and ring current particles in the magnetosphere. This work addresses the long standing problem by examining the source of magnetospheric plasma predicted by the multispecies version of the BATS-R-US MHD code. Two Hydrogen species, one ionospheric in origin and one solar wind in origin, are followed as they progress through the system during idealized simulations of various solar wind drivers. It is found that the magnetosphere has two modes of convection and plasma entry that depend on the solar wind conditions. During southward IMF, convection is reconnection-driven and the dominant source of plasma is ionospheric particles entering near the tail reconnection point. During northward IMF conditions, viscous interactions along the flanks of the magnetosphere drive convection and deliver large amounts of solar wind plasma to the system. These results are examined further by performing real-event simulations and making data-model comparisons using LANL Geosynchronous MPA particle data.

  5. The estimated required minimum flash rate to change the ionosphere dynamics in the electrodynamical coupling model of atmosphere and ionosphere

    NASA Astrophysics Data System (ADS)

    Kuo, C.; Hsu, R.; Huba, J. D.; Chen, A. B.; Su, H.; Lee, L.

    2013-12-01

    We developed an electrodynamical coupling model of atmospheric thunderstorm current system and the ionospheric current system. Using the average flash rate of thunderstorm as a parameter In the coupling model, we calculate the upward current injecting into the ionosphere. From the lower boundary of the ionosphere, the upward current from thunderstorm can be served as input current in the ionospheric current system. With upward current from thunderstorm, the perpendicular electric field is derived using local conductivity tensor at given magnetic latitudes. The associated electric field leads to the plasma ExB drift motion in the ionosphere. The caused plasma motion changes the plasma density, i.e., the changes of observed total electron content. In the nighttime ionosphere, the depletion region caused by thunderstorm current near equator may trigger the plasma bubbles. We also estimate required minimum flash rate to change the ionosphere dynamics. It is found that a cluster of thunderstorms with total flash rate greater than tens of ampere may cause ?TEC ~ 1% and plasma bubbles in the nighttime ionosphere.

  6. Strong ionospheric field-aligned currents for radial interplanetary magnetic fields

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Lhr, Hermann; Shue, Jih-Hong; Frey, Harald. U.; Kervalishvili, Guram; Huang, Tao; Cao, Xue; Pi, Gilbert; Ridley, Aaron J.

    2014-05-01

    The present work has investigated the configuration of field-aligned currents (FACs) during a long period of radial interplanetary magnetic field (IMF) on 19 May 2002 by using high-resolution and precise vector magnetic field measurements of CHAMP satellite. During the interest period IMF By and Bz are weakly positive and Bx keeps pointing to the Earth for almost 10 h. The geomagnetic indices Dst is about -40 nT and AE about 100 nT on average. The cross polar cap potential calculated from Assimilative Mapping of Ionospheric Electrodynamics and derived from DMSP observations have average values of 10-20 kV. Obvious hemispheric differences are shown in the configurations of FACs on the dayside and nightside. At the south pole FACs diminish in intensity to magnitudes of about 0.1 ?A/m2, the plasma convection maintains two-cell flow pattern, and the thermospheric density is quite low. However, there are obvious activities in the northern cusp region. One pair of FACs with a downward leg toward the pole and upward leg on the equatorward side emerge in the northern cusp region, exhibiting opposite polarity to FACs typical for duskward IMF orientation. An obvious sunward plasma flow channel persists during the whole period. These ionospheric features might be manifestations of an efficient magnetic reconnection process occurring in the northern magnetospheric flanks at high latitude. The enhanced ionospheric current systems might deposit large amount of Joule heating into the thermosphere. The air densities in the cusp region get enhanced and subsequently propagate equatorward on the dayside. Although geomagnetic indices during the radial IMF indicate low-level activity, the present study demonstrates that there are prevailing energy inputs from the magnetosphere to both the