Sample records for ionospheric plasma convection

  1. Effects of Ionospheric Conductivity on Convective Flow of Plasma in the Magnetosphere

    Microsoft Academic Search

    R. A. Wolf

    1970-01-01

    Convective flow of plasma in the magnetosphere is apparently driven by the interaction between the solar wind and the magnetosphere, but the flow pattern is regulated by the ionosphere and by pressure gradients in the magnetospheric plasma. The equations for conservation of ionospheric currents are used here to deduce theoretical flow patterns. The currents caused by the pressure of magnetospheric

  2. Ionospheric response to traveling convection twin vortices

    SciTech Connect

    Schunk, R.W.; Zhu, L.; Sojka, J.J. [Utah State Univ., Logan, UT (United States)] [Utah State Univ., Logan, UT (United States)

    1994-08-15

    Traveling convection twin vortices have been observed for several years. At ionospheric altitudes, the twin vortices correspond to spatially localized, transient structures embedded in a large-scale background convection pattern. The convection vortices are typically observed in the morning and evening regions. They are aligned predominantly in the east-west direction and have a horizontal extent of from 500-1000 km. Associated with the twin vortices are enhanced electric fields, particle precipitation, and an upward/downward field-aligned current pair. Once formed, the twin vortex structures propagate in the tailward direction at speeds of several km/s, but they weaken as they propagate and only last for about 10-20 minutes. Because these convection structures might have a significant effect on the localized ionosphere, the USU ionospheric model was used to calculate the response of the ionosphere to {open_quotes}representative{close_quotes} traveling convection twin vortices for a range of background conditions. The ionospheric response includes localized temperature enhancements, ion composition changes, non-Maxwellian ion distributions, and plasma upwelling events. The response is transient and the magnitude of the response depends on the background ionosphere conditions and on the characteristics of the twin vortices. 17 refs., 4 figs.

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

    NASA Astrophysics Data System (ADS)

    Jones, Tudor B.; Leicester, Mark

    1990-12-01

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

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

    NASA Technical Reports Server (NTRS)

    Hirahara, M.; Horwitz, J. L.; Moore, T. E.; Germany, G. A.; Spann, J. F.; Peterson, W. K.; Shelley, E. G.; Chandler, M. O.; Giles, B. L.; Craven, P. D.; Pollock, C. J.; Gurnett, D. A.; Pickett, J. S.; Persoon, A. M.; Scudder, J. D.; Maynard, N. C.; Mozer, F. S.; Brittnacher, M. J.; Nagai, T.

    1998-01-01

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

  5. Relationship of Topside Ionospheric Ion Outflows to Auroral Forms and Precipitations, Plasma Waves, and Convection Observed by POLAR

    NASA Technical Reports Server (NTRS)

    Hirahara, M.; Horwitz, J. L.; Moore, T. E.; Germany, G. A.; Spann, J. F.; Peterson, W. K.; Shelley, E. G.; Chandler, M. O.; Giles, B. L.; Craven, P. D.; Pollock, C. J.; Gurnett, D. A.; Persoon, A. M.; Scudder, J. D.; Maynard, N. C.; Mozer, F. S.; Brittnacher, M. J.; Nagai, T.

    1997-01-01

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

  6. Relationship of topside ionospheric ion outflows to auroral forms and precipitation, plasma waves, and convection

    Microsoft Academic Search

    M. Hirahara; J. L. Horwitz; T. E. Moore; G. A. Germany; J. E Spann; W. K. Peterson; E. G. Shelley; M. O. Chandler; B. L. Giles; P. D. Craven; C. J. Pollock; D. A. Gurnett; J. S. Pickett; A. M. Persoon; J. D. Scudder; N. C. Maynard; F. S. Mozer; M. J. Brittnacher; T. Nagai

    1998-01-01

    The POLAR satellite often observes upflowing ionospheric ions (UFIs) in and near the auroral oval on southern perigee (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

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

    SciTech Connect

    Zhao, J. S.; Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Sciences 210008, Nanjing (China); Yu, M. Y. [Department of Physics, Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44780 Bochum (Germany); Lu, J. Y. [National Center for Space Weather, China Meteorology Administration 100081, Beijing (China)

    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.

  8. 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.

  9. 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.

  10. Relationship of topside ionospheric ion outflows to auroral forms and precipitation, plasma waves, and convection observed by Polar

    Microsoft Academic Search

    M. Hirahara; J. L. Horwitz; T. E. Moore; G. A. Germany; J. F. Spann; W. K. Peterson; E. G. Shelley; M. O. Chandler; B. L. Giles; P. D. Craven; C. J. Pollock; D. A. Gurnett; J. S. Pickett; A. M. Persoon; J. D. Scudder; N. C. Maynard; F. S. Mozer; M. J. Brittnacher; T. Nagai

    1998-01-01

    The POLAR satellite often observes upflowing ionospheric ions (UFIs) in and near the auroral oval on southern perigee (~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

  11. Field aligned plasma coupling between the ionosphere and plasmasphere

    NASA Astrophysics Data System (ADS)

    Maruyama, N.; Richards, P. G.; Fang, T.; Mayer, L.; Fuller-Rowell, T. J.; Richmond, A. D.; Maute, A. I.

    2012-12-01

    The overarching objective of this study is to improve consistent understanding of the altitude coupling and interaction between ionosphere and plasmasphere during storms. From the plasmaspheric viewpoint, during the main phase of a storm, morphology of the plasmasphere, such as characterized by plasmaspheric boundary layers, plumes and erosions, is mainly determined by an increase in the global scale magnetospheric convection, whereas during the recovery phase of the storm, mass loading from the ionosphere tends to dominate the plasmaspheric density variation. On the other hand, from the ionospheric viewpoint, plasma redistribution is generated by the prompt penetration electric field, resulting in the so-called positive storms observed in GPS-TEC. At the same time, the disturbances in the neutral winds and compositions change the ionosphere as well. Although individual viewpoints have been renewed thanks to the recent progress in the observation capabilities, however, we do not have a good overall picture about how the plasma should be flowing between the ionosphere and plasmasphere during storms to explain multiple near simultaneous observations in a consistent manner. The Ionosphere-Plasmasphere-Electrodynamics (IPE) model is used to address the altitude coupling issues between the ionosphere and plasmasphere. The model consists of a physics based model of an ionosphere and plasmasphere using the IGRF geomagnetic field configuration. In this presentation, we will show the response of the plasma field aligned distribution between the ionosphere and plasmasphere during storms, as well as the corresponding TEC variations.

  12. Ann. Geophysicae 14, 1025--1031 (1996) EGS --Springer-Verlag 1996 Travelling convection vortices in the ionosphere map

    E-print Network

    Paris-Sud XI, Université de

    Ann. Geophysicae 14, 1025--1031 (1996) EGS -- Springer-Verlag 1996 Travelling convection vortices in the ionosphere map to the central plasma sheet A. Yahnin*, T. Moretto Danish Meteorological Institute, Solar 1996 Abstract. We investigate the magnetospheric domain re- sponsible for the generation of ionospheric

  13. 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 ?B˜30 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.

  14. 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.

  15. The ionospheres and plasma tails of comets

    Microsoft Academic Search

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

    1977-01-01

    The paper reviews the current state of knowledge about cometary plasma (type I) tails and ionospheres. Observational statistics for type I tails are examined along with spectroscopic observations of plasma tails, identified ion species in such tails, and the morphology of cometary plasma tails and ionospheres. Evidence for a strong interaction between comets and the solar wind is evaluated on

  16. Observations of plasma density structures in association with the passage of traveling convection vortices and the occurrence

    E-print Network

    Paris-Sud XI, Université de

    Observations of plasma density structures in association with the passage of traveling convection of traveling convection vortices (TCV). The other event occurred in association with the development of large-region ionosphere. Key words. Ionosphere (ionospheric irregularities) á Magnetospheric physics (electric ®elds

  17. Plasma interactions in Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Richard, Matthew Scott

    The Cassini mission has collected vast amounts of in situ data within the ionosphere of Saturn's moon Titan and has shown the complexity of the interaction of Saturn's magnetospheric plasma with Titan. Models of the interactions have been created; however, none have been able to completely describe the observed phenomena. Most notably, modeled electron densities are much larger than the electron densities observed by instruments aboard the Cassini spacecraft. This thesis will explore the possible causes of this discrepancy between measured and modeled electron densities using models calculating the production of ions due to solar photons and magnetospheric electrons precipitating down magnetic field lines and into the ionosphere, temperature calculations of the thermal electron population (electrons with energies less than 2 eV), and chemical reactions in the ionosphere. The results of these models will be compared to data collected by instruments aboard Cassini. Modeled ion production rates and thermal electron temperature profiles will be shown to be in good agreement with ion production rates derived from data collected by the Ion -- Neutral Mass Spectrometer (INMS) and electron temperatures measured by the Radio and Plasma Wave Science -- Langmuir Probe above 1000 km. Modeled ion mass spectra will be generated near the ionospheric peak and will be compared with the INMS measured mass spectra to examine the effects of chemical loss processes on the ion densities. From this analysis it will be shown that the overabundance of modeled electrons is not caused by over production of ions and that chemical loss processes, predominantly the electron dissociative recombination coefficient of HCNH+, need to be reexamined. After the model has been proven to reproduce accurate profiles of ion production and temperature, ion production profiles will be generated using solar photons and magnetospheric electron fluxes for four canonical cases detailed in the work of Rymer et al. [2009] and a globally averaged model of the neutral densities based on INMS neutral measurements from more than 30 flybys of Titan. These generic profiles can be combined to predict ionospheric observations made by the Cassini spacecraft for a variety of solar zenith angles and magnetospheric conditions.

  18. Ionospheric convection during different phases of magnetospheric substorms

    NASA Technical Reports Server (NTRS)

    Lester, M.; Fox, N. J.; Reeves, G. D.; Hairston, M.

    1996-01-01

    Observations of ionospheric convection flows at a range of local times during the various phases of the substorm cycle are reported on with the aim of investigating the convection behavior during a range of times and phases. The ionospheric flow observations are from the EISCAT and DMSP satellites. The substorm phases are identified from energetic particle measurements from geosynchronous satellites. The growth phase convection indicates an initial expansion of the polar cap. There is an unexplained poleward motion of the flow reversal boundary (FRB). It is concluded that this motion does not necessarily provide a true representation of the balance between reconnection at the dayside and in the tail. The expansion phase flows do not show any evidence for tail reconnection until late in the phase. The convection during the recovery phase is indicative of tail reconnection as there is evidence that there is only a lobe cell driving convection on the dayside.

  19. 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.

  20. Can the ionosphere regulate magnetospheric convection?

    Microsoft Academic Search

    F. V. Coroniti; C. F. Kennel

    1973-01-01

    Following a southward shift of the interplanetary magnetic field, which implies enhanced reconnection at the nose of the magnetosphere, the magnetopause shrinks from its ChapmanFerraro equilibrium position. If the convective return of magnetic flux to the magnetopause equaled the reconnection rate, the magnetopause would not shrink. Consequently, there is a delay in the development of magnetospheric convection following the onset

  1. C/NOFS and radar observations during a convective ionospheric storm event over South America

    NASA Astrophysics Data System (ADS)

    Kelley, M. C.; Rodrigues, F. S.; Makela, J. J.; Tsunoda, R.; Roddy, P. A.; Hunton, D. E.; Retterer, J. M.; de La Beaujardiere, O.; de Paula, E. R.; Ilma, R. R.

    2009-08-01

    The development of a convective ionospheric storm is studied using three radars, the C/NOFS satellite, airglow instrumentation, and a numerical model. First detected in the form of convective plumes over the Eastern Pacific, plasma irregularities, airglow signatures, plumes, and irregularities were also detected over Brazil and then Peru. Dynamo conditions were such that a modest prereversal enhancement was recorded at both Christmas Island and Peru and probably over Brazil as well. No prereversal enhancement occurred during the next two days and no plumes were detected. The numerical model reproduced the results quite well over Peru. Evidence for seeding by both gravity waves and the Kelvin-Helmholtz instability is presented.

  2. The response of the large scale ionospheric convection pattern to changes in the IMF and substorms - Results from the SUNDIAL 1987 campaign

    NASA Astrophysics Data System (ADS)

    Lester, M.; de La Beaujardiere, O.; Foster, J. C.; Freeman, M. P.; Luehr, H.; Ruohoniemi, J. M.; Swider, W.

    1993-07-01

    Multipoint observations of ionospheric convection, made during the SUNDIAL 1987 campaign (May 29 to June 8) which included two intervals of variable IMF Bz and By and several substorms, are used to examine the response of the ionospheric convection in the postdusk and midnight sectors to changes in the IMF Bz component, as well as the effect of substorms on ionospheric convection. It was found that the primary ionospheric effect of a change in the IMF from positive Bz to negative Bz is an enhancement in plasma flow magnitude. The response time of the ionospheric convection to each southward turning varies from 15 min near 1800 MLT to 30 min near 2100 MLT and close to one hour near midnight. During one of the substorms, which consisted of several intensifications, the nightside flow reversal moved progressively to earlier local times in response to each substorm intensification.

  3. Magnetospheric control of the bulk ionospheric plasma

    SciTech Connect

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

    1987-01-01

    The temperature, composition, and circulation of the high-latitude, ionosphere display a marked variation with altitude, latitude, longitude, universal time, season, solar cycle, and geomagnetic activity. This variation is largely a consequence of the effect that magnetospheric electric fields, particle precipitation, and heat flows have on the ionosphere. At F-region altitudes, the entire ionosphere drifts in response to magnetospheric electric fields, with the horizontal drift generally displaying a two-cell pattern of antisunward flow over the polar cap and return flow at lower latitudes. This ionospheric motion, in combination with downward magnetospheric heat flows and ion production due to energetic-particle precipitation, act to produce interesting ionospheric features such as ion and electron temperature hot spots, plasma blobs, localized ionization troughs, and extended tongue of ionization, and anomalous F-region peak altitudes and densities. The time delay for the ionosphere to respond to changing magnetospheric conditions is a strong function of altitude and can be as long as 3 to 4 hours in the upper F-region. The ionosphere's response to changing magnetospheric conditions are described using a time-dependent high-latitude ionospheric model.

  4. The ionospheric signature of transient dayside reconnection and the associated pulsed convection return ow

    E-print Network

    Boyer, Edmond

    The ionospheric signature of transient dayside reconnection and the associated pulsed convection to investigate the excitation of convection in the dayside high-latitude ionosphere in response to transient. Moreover, transient sunward-propagating re- gions of backscatter are observed in the convection return ¯ow

  5. Plasma Channels in the Venus Nightside Ionosphere

    NASA Astrophysics Data System (ADS)

    Perez-de-Tejada, H.

    Pioneer Venus Orbiter (PVO) data with information on ionospheric holes in the Venus nightside hemisphere are examined in a study of the plasma channels that extend downstream from the magnetic polar regions. These latter features are produced by the solar wind that erodes the polar upper ionosphere and provide a useful interpretation of the ionospheric holes as regions of depleted plasma density that the PVO traverses in its near polar trajectory through the nightside ionosphere [Pérez-de-Tejada, J. Gephys. Res. 106, 211, 2001]. Data obtained from the PVO Orbiting Electron Temperature Probe (OETP) show that in addition to the ionospheric holes there are orbits in which the electron density remains nearly uniform when it is measured from the high altitude nightside ionopause to very low altitudes along trajectories oriented near the midnight plane. In addition there are some passes in which the nightside ionopause occurs at very low heights (near the trajectory periapsis) and thus imply that no significant electron densities are observed along sections of the trajectory where a strong ionosphere is observed in other orbits. This latter circumstance is remarkable in that it is not necessarily associated with high values of the solar wind dynamic pressure but is present even when the nightside ionopause far from the midnight plane is detected at high altitudes. In such cases it is possible that as the PVO approaches or moves away from periapsis it is located within the plasma channels that extend downstream from the magnetic polar regions and thus skips transit through the nightside upper ionosphere. An important aspect of this view is that it can account for the sharp change of the electron density that is seen within the ionosphere at altitudes that correspond to crossings near the lower boundary of the plasma channels.

  6. Ionosphere-magnetosphere coupling. I - Thermal plasma

    NASA Technical Reports Server (NTRS)

    Chappell, C. R.

    1975-01-01

    The complex interaction of the cold plasma of the plasmasphere and ionosphere with the hot plasma of the ring current and the plasma sheet is studied. It is seen that a coupling, probably through wave particle interactions, exists which seems to have a strong influence on the temperature of the plasma of the outer plasmasphere and on the detailed dynamics of the bulge region, especially the formation of detached plasma regions or plasma tails. Also, there is evidence that the outer plasmasphere may display very high temperatures, and that detached plasma regions are closely associated with ring current injections.

  7. Plasma Interactions in Titan's Ionosphere

    E-print Network

    Richard, Matthew

    2013-05-31

    calculations of the thermal electron population (electrons with energies less than 2 eV), and chemical reactions in the ionosphere. The results of these models will be compared to data collected by instruments aboard Cassini. Modeled ion production rates...

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  9. Spherical cap harmonic analysis of Super Dual Auroral Radar Network (SuperDARN) observations for generating maps of ionospheric convection

    NASA Astrophysics Data System (ADS)

    Fiori, R. A. D.; Boteler, D. H.; Koustov, A. V.; Haines, G. V.; Ruohoniemi, J. M.

    2010-07-01

    A spherical cap harmonic analysis (SCHA) technique is introduced for mapping the 2-D high-latitude ionospheric convection pattern based on Super Dual Auroral Radar Network (SuperDARN) velocity measurements. The current method for generating such maps is the FIT technique which generates global-scale maps over the entire convection region. This is accomplished by combining observations with a statistical model to prevent unphysical solutions in areas away from the observation points and by forcing the plasma flow to zero at the low-latitude boundary of the convection zone. Both constraints distort the mapped convection and require a preconception of where the plasma flow lines should close. By focusing on mapping the convection over a region well covered by velocity observations, the SCHA technique is freed of these constraints and more accurately reproduces local convection. We generate large-scale convection maps from SuperDARN data for various interplanetary magnetic field (IMF) conditions during periods of widespread radar coverage to show the patterns are consistent with expectations for various IMF configurations. We validate the SCHA maps by comparing them with the 2-D ion drifts measured by the DMSP satellites and with the 2-D convection vectors obtained by merging SuperDARN measurements at beam crossings. The SCHA technique is shown to perform comparably to the FIT technique over regions of good data coverage. For limited data coverage and over regions of highly variable flow, particularly near the equatorward edge of the mapping region, the SCHA technique provides a better solution for mapping ionospheric convection based on SuperDARN radar observations.

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

    Microsoft Academic Search

    Mark A. McHenry; C. Robert Clauer; Eigil Friis-Christensen

    1990-01-01

    In a companion paper the authors have shown that many continuous, dayside, high latitude magnetic pulsations are caused by steady, traveling ionospheric convection vortices (McHenry et al. this issue). A variety of evidence indicates that these vortices are the ionospheric signatures of the Kelvin-Helmholtz instability at the inner edge of the magnetospheric boundary layer. In this paper the authors present

  11. Interplanetary magnetic field effects on high latitude ionospheric convection

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.

    1985-01-01

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  14. Interaction of the Saturnian Magnetospheric Plasma with Titan's Ionosphere: Formation of a Ionopause

    Microsoft Academic Search

    H. Backes; F. M. Neubauer

    2001-01-01

    The interaction of Titan with the ambient plasma has many faces since the determining parameters (ionospheric composition and ambient plasma properties) vary substantially in time. The main ionization source for Titan's ionosphere is the solar EUV radiation. Thus, the nightside ionosphere differs completely from the dayside ionosphere. The magnetospheric plasma in the plasma mantle is highly variable in time. Apart

  15. First measurements of the ionospheric plasma escape from Mars

    Microsoft Academic Search

    R. Lundin; H. Borg; B. Hultqvist; A. Zakharov; R. Pellinen; N. Pissarenko; E. M. Dubinin; S. W. Barabash; I. Liede; H. Koskinen

    1989-01-01

    The results are reported of an ion-composition experiment on board the Phobos 2 spacecraft which was used to determine the loss of plasma from the Martian ionosphere. Surprisingly, there are many similarities between the ionospheric outflow from Mars and earth. The ion loss from Mars results from both ion pickup due to mass-loading of the solar wind in the Martian

  16. Magnetospheric and ionospheric plasmas; Proceedings of the Ninth Symposium and Topical Meeting, Graz, Austria, June 25-July 7, 1984

    SciTech Connect

    Schmerling, E.R.; Cowley, S.W.H.; Reiff, P.H.

    1985-01-01

    Papers are presented on the physics of the magnetosphere-ionosphere connection, with attention given to theory and modeling, auroras, plasma dynamics and irregularities, waves and electron beams, the dynamics of the thermosphere, and planetary plasmas. Plasma circulation in the magnetosphere is also discussed; consideration is given to observations of magnetospheric convection from low altitudes, the structure and properties of the earth's plasmasphere, and the circulation of energetic ions of terrestrial origin in the magnetosphere.

  17. Cassini measurements of cold plasma in the ionosphere of Titan.

    PubMed

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

    2005-05-13

    The Cassini Radio and Plasma Wave Science (RPWS) Langmuir probe (LP) sensor observed the cold plasma environment around Titan during the first two flybys. The data show that conditions in Saturn's magnetosphere affect the structure and dynamics deep in the ionosphere of Titan. The maximum measured ionospheric electron number density reached 3800 per cubic centimeter near closest approach, and a complex chemistry was indicated. The electron temperature profiles are consistent with electron heat conduction from the hotter Titan wake. The ionospheric escape flux was estimated to be 10(25) ions per second. PMID:15894529

  18. Plasma temperatures in Saturn's ionosphere Luke Moore,1

    E-print Network

    Mendillo, Michael

    Plasma temperatures in Saturn's ionosphere Luke Moore,1 Marina Galand,2 Ingo Mueller-Wodarg,2 Roger the height of peak electron density, while they can reach 500 K during the day at the topside. Plasma scale of Saturn have been used to estimate plasma temperature as a comparison. Such an estimate agrees well

  19. Plasma Waves in an Inhomogeneous Ionosphere Carl Caleman

    E-print Network

    of electromagnetic waves and plasma waves. At an early stage in the history of plasma physics the importancePlasma Waves in an Inhomogeneous Ionosphere Carl Caleman 8th April 2003 #12;Abstract is the reason why short wave radio waves can propagate around earth. To understand what happens when the radio

  20. Morphology of meteoric plasma layers in the ionosphere of Mars

    E-print Network

    Withers, Paul

    Morphology of meteoric plasma layers in the ionosphere of Mars as observed by the Mars Global Radio Science data #12;Meteoric Plasma Layer EUV layer X-ray layer Meteoric layer Layer at 90 km Observations · 71 meteoric plasma layers in 5600 MGS profiles 5217R00A 4353T31A 3176Q39A 0350E42B #12

  1. Modeling the observed proton aurora and ionospheric convection responses to changes in the IMF clock angle

    E-print Network

    Lockwood, Mike

    Modeling the observed proton aurora and ionospheric convection responses to changes in the IMF clock angle: 1. Persistence of cusp proton aurora K. Throp, M. Lockwood,1 B. S. Lanchester, and S. K employ a numerical model of cusp ion precipitation and proton aurora emission to fit variations

  2. Radio Pumping of Ionospheric Plasma with Orbital Angular Momentum

    Microsoft Academic Search

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

    2009-01-01

    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

  3. 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.

  4. Evidence That IMF Fluctuations During High-Speed Solar Wind Steams Substantially Affect the Strength of Dayside Ionospheric Convection

    NASA Astrophysics Data System (ADS)

    Kim, H.; Lyons, L. R.; Boudouridis, T.; Zou, S.; Heinselman, C.; McCready, M.

    2008-12-01

    The orientation and magnitude of the interplanetary magnetic field (IMF) and solar wind dynamic pressure are known to affect the strength of ionospheric convection. However, the high-speed solar wind streams during the IPY have provided the opportunity to investigate whether the ULF waves of the IMF during high- speed streams can have a substantial contribution to the strength of convection. We have examined ionospheric convection in the dayside polar cap measured by the Sondrestrom radar under various solar wind conditions. Using an extensive radar data set, we find that ULF power in the IMF is closely associated with the strength of dayside ionospheric convection. Convection flows during periods of large north-south IMF fluctuations are observed to be as strong as for steady and large southward IMF periods. Enhanced convection can be also observed even for northward IMF intervals, but only if the interplanetary magnetic field exhibits high ULF power. These observations thus suggest that IMF wave activity can significantly influence ionospheric convection. Comparisons with events with substantial ULF power not occurring during high-speed streams indicate that the ULF power is effective, independent of any direct affect from the solar wind speed. We speculate that resonance between IMF fluctuations and natural magnetospheric oscillation frequencies might be responsible for the connection between ionospheric convection and IMF ULF power. We have also found some evidence for a connection between the ULF power in the solar wind density and the strength of convection.

  5. Small-scale irregularities and global plasma dynamics in the high-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Hanuise, C.; Greenwald, R. A.; Baker, K. B.; Ruohoniemi, J. M.; Cerisier, J. C.; Senior, Catherine

    1989-04-01

    New sophisticated HF coherent radars were installed in the past few years at very high latitudes. The APL Goose Bay radar and the French SHERPA radar in Schefferville are the two components of the Polar Region Ionospheric Structrure Monitor (PRISM) operating in Canada. These instruments detect irregularities within the three-dimensional volume covering much of northeastern Canada and Greenland. The instruments are capable of following the temporal variability of these irregularities as well as determining unambiguously the Doppler shift and spectral broadening of radar signals scattered by them. The scientific goals of the program concern both the physics of the small-scale structures and the mapping of large-scale plasma convection. Several case studies of plasma mechanisms generating the small-scale density structures were already published. The temporal and spatial variability of the large-scale irregularity structures, as seen by the radars, is also investigated. The relationship between the radar Doppler velocity and the plasma drift velocity were confirmed. The potential of the system for studying global ionospheric dynamics is emphasized. When combining the two radial velocities measured by each radar, a two-dimensional map of plasma convection and electric field is derived over a region as large as 2 million square kilometers, with a fine temporal and spatial resolution in the auroral region and over the polar cap.

  6. Effect of magnetospheric convection on thermal plasma in the inner magnetosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Rasmussen, C. E.; Konikov, Yu. V.; Gombosi, T. I.; Nagy, A. F.

    1994-01-01

    The effects of E x B convection on the distribution of plasma parameters in the inner magnetosphere have been examined. Analytical solutions describing density distributions along convective trajectories in the equatorial plane have been found. These solutions suggest the following dependence of plasma concentration n on the magnetic field B along convective trajectories: n proportional to B(exp alpha), where the parameter alpha varies between alpha is less than or = between 4/3 and 2. The alpha = 2 case corresponds to disregarding transport parallel to B. The lower bound alpha = 4/3 describes the situation when parallel transport dominates over convective motions perpendicular to B. A solution has also been obtained describing the effect of convection on diffusive equilibrium profiles in the dayside plasmasphere. In addition, ion temperature variations due to adiabatic effects associated with plasma convection have been analyzed in detail. Convective drifts lead to ion temperature anisotropies with the value and sign of the anisotropy contingent on density and temperature variations, local time, and the location of the convective trajectory with respect to the location of the plasmapause. We have also found that convective motions lead to a substantial exchange of energy between the ionosphere and the plasmasphere through electron heat fluxes.

  7. Dynamics of Ionospheric Plasma Depletions Measured by Airglow Emissions

    NASA Astrophysics Data System (ADS)

    Chapagain, Narayan; Taylor, Michael

    2010-10-01

    The earth's ionosphere most often shows the occurrence of highly irregular plasma density and velocity fluctuations with a large range of scale sizes and amplitudes. This night time ionospheric irregularities in the equatorial F-region is commonly referred to as equatorial spread F or plasma depletions (bubbles). In this presentation, we analyze the development and dynamics of the equatorial plasma depletions observed using OI (630.0 nm) airglow emissions measured by Utah State University all-sky CCD camera from different longitude sectors near equatorial regions including Christmas Island in Pacific Ocean, Ascension Island in Atlantic Ocean, and Brazil. The results illustrate the large day-to-day variability of the plasma bubbles evolution and development from all sites. The plasma bubble structures propagated eastward during the nighttime. The development of bubbles and the magnitude of the zonal drift velocities during the post midnight period were significantly longitudinal dependence.

  8. Direct Access to Plasma Resonance in Ionospheric Radio Experiments

    Microsoft Academic Search

    Einar Mjølhus; Tor FlÅ

    1984-01-01

    The concept of linear conversion of radio waves into electrostatic (ES) waves is adapted to ionospheric radio heating experiments. It is identified as access to the plasma resonance through the radio window. By means of existing heating facilities, large concentrations of electrostatic wave energy can be generated. The ES waves are confined to a restricted region in space, horizontally displaced

  9. Microwave Discharge Oxygen Ion Source for Ionospheric Plasma Environment Simulation

    Microsoft Academic Search

    Hiroshi Hayashi; Mengu Cho; Kazutaka Nishiyama; Hitoshi Kuninaka

    2005-01-01

    In recent years, concern has been raised about the interference phenomena (chemical reaction, sputtering etc.) between ionospheric plasma and high-voltage space systems such as the International Space Station and so on. In order to solve the physical mechanisms of these phenomena and establish the prevention technology, it is important to accumulate experimental data based on ground simulation tests. Therefore we

  10. Meteor Plasmas in the E-Region Ionosphere

    NASA Astrophysics Data System (ADS)

    Dimant, Y. S.; Oppenheim, M. M.

    2012-10-01

    Every day billions of tiny meteoroids impact the Earth's atmosphere at hypersonic speeds, creating dense plasmas between 80 and 130 km altitude. In this part of the E-region ionosphere electrons are magnetized by the geomagnetic field while ions are largely unmagnetized due to their frequent collisions with neutral atmosphere. This discrepancy leads to a variety of inhomogeneous, unstable, and nonlinear plasma phenomena. Among them is the formation of field-aligned irregularities in the slowly diffusing dense meteor plasma trails which are important for radar observations of mostly optically invisible meteors. We will present a quantitative model of the evolution of a plasma trail density and its ambipolar electric fields. Our theory predicts that plasma trail diffusion induces electric currents through a large volume of the background ionosphere with important consequences for plasma trail diffusion. Also, strong electric fields propagate long distances along the magnetic field lines from the dense plasma trail deep into the tenuous ionosphere and create significant disturbances of the background density. This may explain radar and rocket observations of extensive nighttime E-region density structures.

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

    E-print Network

    Bergen, Universitetet i

    ionosphere. Low energy ions travel along the magnetic field lines and enter the magnetospheric lobes whereEstimating the capture and loss of cold plasma from ionospheric outflow S. Haaland,1,2 A. Eriksson of cold plasma from ionospheric outflow, J. Geophys. Res., 117, A07311, doi:10.1029/2012JA017679. 1

  12. Some aspects of modelling the high-latitude ionospheric convection from Cluster/Edi data

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    Measurements onboard Cluster satellites are briefly described, which form the base for determining the intensity and direction of the electric field in the magnetosphere. The aim of this paper is to describe (1) the methodology of calculating the potential distribution at the ionospheric level and the results of constructing spatiotemporal convection patterns for different orientations of the IMF vector in the GSM YZ plane; (2) derivation of basic convection patterns (BCPs), which allow to deduce the statistical ionospheric convection pattern at high latitudes for any IMF Bz and By values (statistical convection model) using different sets of independent data; (3) the consequences of enlarging the amount of data used for analysis; (4) the results of potential calculations with various orders of the spherical harmonics describing them; (5) determination of the cross-polar cap potential with different IMF sector widths (? from 45° down to 10°); (6) the results of our trials to determine the contribution of the IMF Bx component to the convection pattern.

  13. DEMETER Observations of Equatorial Plasma Depletions and Related Ionospheric Phenomena

    NASA Astrophysics Data System (ADS)

    Berthelier, J.; Malingre, M.; Pfaff, R.; Jasperse, J.; Parrot, M.

    2008-12-01

    DEMETER, the first micro-satellite of the CNES MYRIAD program, was launched from Baikonour on June 29, 2004 on a nearly circular, quasi helio-synchronous polar orbit at ~ 715 km altitude. The DEMETER mission focuses primarily on the search for a possible coupling between seismic activity and ionospheric disturbances as well as on the effects of natural phenomena such as tropospheric thunderstorms and man-made activities on the ionosphere. The scientific payload provides fairly complete measurements of the ionospheric plasma, energetic particles above ~ 70 keV, and plasma waves, up to 20 kHz for the magnetic and 3.3 MHz for the electric components. Several studies related to space weather and ionospheric physics have been conducted over the past years. Following a brief description of the payload and the satellite modes of operation, this presentation will focus on a set of results that provide a new insight into the physics of instabilities in the night-time equatorial ionosphere. The observations were performed during the major magnetic storm of November 2004. Deep plasma depletions were observed on several night-time passes at low latitudes characterized by the decrease of the plasma density by nearly 3 orders of magnitude relative to the undisturbed plasma, and a significant abundance of molecular ions. These features can be best interpreted as resulting from the rise of the F-layer above the satellite altitude over an extended region of the ionosphere. In one of the passes, DEMETER was operated in the Burst mode and the corresponding high resolution data allowed for the discovery of two unexpected phenomena. The first one is the existence of high intensity monochromatic wave packets at the LH frequency that develop during the decay phase of intense bursts of broadband LH turbulence. The broadband LH turbulence is triggered by whistlers emitted by lightning from atmospheric thunderstorms beneath the satellite. The second unexpected feature is the detection of a population of super-thermal ionospheric ions with a density of about 2-3% of the thermal ion population. The super- thermal ions appeared to be heated to temperatures of a few eV at times when LH turbulence and monochromatic wave packets are observed while the temperature of the core ion population is not affected. High time resolution plasma density measurements show the presence of strong small scale plasma irregularities in the depletions that scatter the high amplitude whistler waves and may lead to the development of strong LH turbulence and of monochromatic wave packets. The ensuing interaction between these waves and the ambient ions may lead to the formation of a super-thermal tail in the ion distribution function. Ion acceleration by LH turbulence and solitary waves is a commonly observed phenomenon along auroral magnetic field lines but, to our knowledge, this is the first time that a similar process has been observed in the equatorial ionosphere. These findings exemplify a novel coupling mechanism between the troposphere and the ionosphere: Under highly disturbed conditions at times of magnetic storms, part of the energy released by lightning and radiated as whistlers can dissipate in the equatorial ionosphere and produce super-thermal ion populations.

  14. 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

  15. New Forms of Convection in Galaxy Cluster Plasmas

    E-print Network

    Wurtele, Jonathan

    New Forms of Convection in Galaxy Cluster Plasmas (i.e., how do galaxy clusters boil?) Eliot · Hot Plasma in Clusters of Galaxies · Hydrodynamic Convection (`normal' convection; e.g., the sun of Galaxies · largest gravitationally bound objects: · ~ 84% dark matter; ~ 14 % plasma; ~ 2% stars

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

    SciTech Connect

    Whitten, R.C.; Barnes, A. (NASA Ames Research Center, Moffet Field, CA (USA)); McCormick, P.T. (Santa Clara Univ., CA (USA))

    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.

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

    SciTech Connect

    McHenry, M.A.; Clauer, C.R. (Stanford Univ., CA (USA)); Friis-Christensen, E. (Danish Meteorological Inst., Copenhagen (Denmark))

    1990-09-01

    In a companion paper the authors have shown that many continuous, dayside, high latitude magnetic pulsations are caused by steady, traveling ionospheric convection vortices (McHenry et al. this issue). A variety of evidence indicates that these vortices are the ionospheric signatures of the Kelvin-Helmholtz instability at the inner edge of the magnetospheric boundary layer. In this paper the authors present the results of a statistical study of the occurrence of these vortices and the upstream solar wind parameters observed by the IMP 8 spacecraft. Surveying fifty days of Greenland west coast chain magnetometer data indicates this class of pulsations is most likely to be detected post local noon and when the solar wind speed is low. However, it is possible that observational factors significantly affect the detection of the vortices. the slow solar wind might create large, slow moving traveling vortices of steady strength which are easiest to identify. Little correlation is found between the average IMF and the probability of detecting the vortices. They also find a strong correlation between the frequency of dayside pulsations and the solar wind speed. This suggests that many pulsations are caused by traveling ionospheric current systems that map to the vicinity of the flows in the magnetospheric boundary layer. Periods also exist when the IMF is variable and large pulsations with 5 to 20 min period exist. These pulsations are not caused by traveling ionospheric vortices but are likely to be the result of rapid variations of the large scale field-aligned cusp currents.

  18. Computer Simulation of Convective Plasma Cells

    E-print Network

    Carboni, Rodrigo

    2015-01-01

    Computer simulations of plasmas are relevant nowadays, because it helps us understand physical processes taking place in the sun and other stellar objects. We developed a program called PCell which is intended for displaying the evolution of the magnetic field in a 2D convective plasma cell with perfect conducting walls for different stationary plasma velocity fields. Applications of this program are presented. This software works interactively with the mouse and the users can create their own movies in MPEG format. The programs were written in Fortran and C. There are two versions of the program (GNUPLOT and OpenGL). GNUPLOT and OpenGL are used to display the simulation.

  19. Whistler-mode wave interactions with ionospheric plasmas over Arecibo

    Microsoft Academic Search

    A. Labno; R. Pradipta; M. C. Lee; M. P. Sulzer; L. M. Burton; J. A. Cohen; S. P. Kuo; D. L. Rokusek

    2007-01-01

    The Naval transmitter, code-named NAU, in Puerto Rico emits radio waves at a power and frequency of 100 kW and 40.75 kHz, respectively. The NAU-generated 40.75 kHz whistler-mode waves are intense enough to excite lower hybrid waves and zero-frequency field-aligned ionospheric irregularities over Arecibo. It is proposed that NAU is responsible for causing the enhanced plasma lines, detected by the

  20. Artificial Periodic Inhomogeneities of the Ionosperic Plasma as a Promising Line in the Ionospheric Research

    Microsoft Academic Search

    E. A. Benediktov; V. V. Belikovich; N. V. Bakhmet'eva; A. V. Tolmacheva

    2002-01-01

    This paper is dedicated to a new method of ionospheric studies, developed at the Radiophysical Research Institute (NIRFI) and based on the creation of artificial periodic inhomogeneities (APIs) of the ionospheric plasma. We review the techniques and present the results of determination of the basic parameters of the ionosphere and atmosphere.

  1. The ionosphere as a fully adequate source of plasma for the earth's magnetosphere

    Microsoft Academic Search

    C. R. Chappell; T. E. Moore; J. H. Jr. Waite

    1987-01-01

    A series of recent measurements of the outflow of ionization from the ionosphere have further heightened the awareness of the strength of the ionospheric source of magnetospheric plasmas. In this paper the ionospheric contribution of the polar wind and cleft ion fountain at energies less than 10 eV has been added to the previously measured sources; this total ion outflow

  2. Are plasma depletions in Saturn's ionosphere a signature of time-dependent water input?

    E-print Network

    Mendillo, Michael

    Are plasma depletions in Saturn's ionosphere a signature of time- dependent water input? Luke Moore the presence of numerous ``ionospheric holes'', or plasma depletions, in Saturn's upper atmosphere that cannot the observed plasma depletions. The required influxes present a target to assess for the possible sources

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  4. The response of the large scale ionospheric convection pattern to changes in the IMF and substorms - Results from the SUNDIAL 1987 campaign

    Microsoft Academic Search

    M. Lester; O. de La Beaujardiere; J. C. Foster; M. P. Freeman; H. Luehr; J. M. Ruohoniemi; W. Swider

    1993-01-01

    Multipoint observations of ionospheric convection, made during the SUNDIAL 1987 campaign (May 29 to June 8) which included two intervals of variable IMF Bz and By and several substorms, are used to examine the response of the ionospheric convection in the postdusk and midnight sectors to changes in the IMF Bz component, as well as the effect of substorms on

  5. Radio Pumping of Ionospheric Plasma with Orbital Angular Momentum

    SciTech Connect

    Leyser, T. B. [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden); Norin, L. [Department of Physics and Astronomy, Uppsala University, Box 515, Uppsala SE-751 20 (Sweden); McCarrick, M. [BAE SYSTEMS Advanced Technologies, 1250 24th St, NW, Suite 850, Washington, D.C. (United States); Pedersen, T. R. [Air Force Research Laboratory, Hanscom Air Force Base, Massachusetts 01731 (United States); Gustavsson, B. [Department of Physics and Technology, University of Tromsoe, N-9037 Tromsoe (Norway)

    2009-02-13

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

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

    SciTech Connect

    Robertson, Scott [Professor

    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.

  7. 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.

  8. Stimulated plasma waves in the ionosphere

    Microsoft Academic Search

    Robert F. Benson

    1977-01-01

    observed above ( (at the maximum frequency of the Bernstein modes) and the (Dn resonances observed below ( (called the diffuse resonances). Most of the resonances can be interpreted in terms of the reception of longitudinal plasma waves stimulated by the sounder pulse. In some cases these waves, which travel with low group velocity (of the order of the electron

  9. An assessment of the "map-potential" and "beam-swinging" techniques for measuring the ionospheric convection pattern using data from the SuperDARN radars

    NASA Astrophysics Data System (ADS)

    Provan, G.; Yeoman, T. K.; Milan, S. E.; Ruohoniemi, J. M.; Barnes, R.

    2002-02-01

    The SuperDARN HF coherent scatter radars (Greenwald et al., 1995) provide line-of-sight (l-o-s) velocity measurements of ionospheric convection flow over the polar regions of the northern and southern hemispheres. A number of techniques have been developed in order to obtain 2-D plasma flow vectors from these l-o-s observations. This study entails a comparison of the ionospheric flow vectors derived using the "map-potential", and "beam-swinging" techniques with the vectors derived using the "merging" technique. The merging technique is assumed to be the most accurate method of deriving local flow vectors from l-o-s velocities. We can conclude that the map-potential model is significantly more successful than the beam-swinging technique at estimating both the magnitude and the direction of the large-scale ionospheric convection flow vectors. The quality of the fit is dependent on time of day, with vectors observed at low latitudes in the dawn sector agreeing most closely with the merged vector flow pattern.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  12. Relation Between Ionospheric Plasma Irregularities at High Latitudes and Auroral Phenomena

    NASA Astrophysics Data System (ADS)

    Ritter, P.; Park, J.; Luhr, H.

    2012-12-01

    Ionospheric irregularities at low-latitudes, known as equatorial plasma bubbles, tend to occur preferably at post-sunset hours when the vertical plasma velocity during the pre-reversal enhancement is particularly strong. Recently, significant occurrence rates of plasma irregularities have also been reported in the high-latitude regions. Their generation mechanisms are quite different and at present still not fully understood. As these irregularities tend to cluster in three prominent regions of the polar area - cusp, polar cap, and pre-midnight substorm onset sector - we investigate their characteristics for these regions separately. One suggestion for high-latitude irregularity generation is ionisation by soft electron precipitations. These beams of soft electrons are commonly accompanied by bursts of small-scale field-aligned currents (FAC). In a superposed epoch analysis we investigate the relation between the occurrences of plasma irregularities and collocated small-scale FACs. In the cusp, a clear coincidence of the two phenomena is observed. Conversely, in the polar cap small-scale FACs are not so frequent. Therefore we suggest a transport of the irregularities from the cusp region into the polar cap by the general anti-sunward plasma convection pattern. In order to discuss possible relations between plasma irregularities detected in the pre-midnight sector and substorm phases we also compare the event times with the substorm catalogue of Frey and Mende (2006).

  13. Ionospheric Ducts and Plasma Waves Induced by HF Heater over Gakona

    Microsoft Academic Search

    J. A. Cohen; L. M. Burton; R. Pradipta; A. Labno; M. C. Lee; S. P. Kuo; B. J. Watkins; S. Oyama

    Ionospheric HF heating experiments were conducted at Gakona, Alaska to investigate (1) ionospheric ducts (viz., large plasma sheets acting as parallel-plate waveguides) and (2) cascading spectra of Langmuir wave turbulence, excited by large- and short-scale plasma instabilities, respectively. The first subject is inspired by our earlier Arecibo experiments (Lee et al., 1998) whereby sheet-like ionospheric ducts were generated by HF

  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. Solar Wind Driven Plasma Fluxes from the Venus Ionosphere

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  16. 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.

  17. Neutral beam injection and plasma convection in a magnetic field

    SciTech Connect

    Okuda, H.; Hiroe, S.

    1988-06-01

    Injection of a neutral beam into a plasma in a magnetic field has been studied by means of numerical plasma simulations. It is found that, in the absence of a rotational transform, the convection electric field arising from the polarization charges at the edges of the beam is dissipated by turbulent plasma convection, leading to anomalous plasma diffusion across the magnetic field. The convection electric field increases with the beam density and beam energy. In the presence of a rotational transform, polarization charges can be neutralized by the electron motion along the magnetic field. Even in the presence of a rotational transform, a steady-state convection electric field and, hence, anomalous plasma diffusion can develop when a neutral beam is constantly injected into a plasma. Theoretical investigations on the convection electric field are described for a plasma in the presence of rotational transform. 11 refs., 19 figs.

  18. 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.

  19. 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.

  20. Plasma Oscillations of charged Dust in the Ionosphere

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

  1. The temperature gradient drift instability at the equatorward edge of the ionospheric plasma trough

    Microsoft Academic Search

    Mary K. Hudson; M. C. Kelly

    1976-01-01

    In this paper we have examined the fluid equations relevant to the ionosphere above 400 km in a region of horizontal gradients in plasma density and electron temperature such as those detected near the ionospheric projection of the plasmapause. The equations are unstable to growth of the temperature gradient drift mode. Electric field fluctuations have been observed in this region

  2. Excitation and diagnosis of cascading Langmuir waves in ionospheric plasmas at Gakona, Alaska

    Microsoft Academic Search

    L. M. Burton; J. A. Cohen; R. Pradipta; A. Labno; M. C. Lee; O. Batishchev; D. L. Rokusek; S. P. Kuo; B. J. Watkins; S. Oyama

    2008-01-01

    Ionospheric plasma heating experiments were conducted at Gakona, Alaska to investigate cascading spectra of Langmuir wave turbulence, excited by parametric instabilities diagnosed by Modular UHF Ionospheric Radar (MUIR). This work is aimed at testing the recent theory of Kuo and Lee (2005 J. Geophys. Res. 110 A01309) that addresses how the cascade of Langmuir waves can distribute spatially via the

  3. JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS, VOL. 118, 24192427, doi:10.1002/jgra.50244, 2013 Large-scale ionospheric disturbances due to the dissipation

    E-print Network

    Vadas, Sharon

    of traveling ionospheric disturbances (TIDs) [Hocke and Schlegel, 1996; Klostermeyer, 1972], which may seed Large-scale ionospheric disturbances due to the dissipation of convectively-generated gravity waves over large-scale perturbations of the plasma drift and plasma density in the ionosphere by changing the wind

  4. In-situ measurements of plasma parameters in the equatorial ionosphere by the resonance cone technique

    NASA Astrophysics Data System (ADS)

    Thiemann, H.; Piel, A.; Gupta, S. P.

    Resonance cone data obtained during a joint Indo-German rocket campaign in the equatorial ionosphere are presented. Plasma parameters are derived from the experimental data and compared with standard Langmuir probe measurements.

  5. A 2-D comparison of ionospheric convection derived from SuperDARN and DMSP measurements

    NASA Astrophysics Data System (ADS)

    Xu, L.; Koustov, A. V.; Xu, J. S.; Drayton, R. A.; Huo, L.

    2008-10-01

    Ion drift vectors measured by the DMSP satellites are compared with plasma convection vectors obtained by the SuperDARN HF radars through the standard Map Potential algorithm of Ruohoniemi and Baker [Ruohoniemi, M., Baker, K.B. Large-scale imaging of high-latitude convection with super dual auroral radar network HF radar observations. J. Geophys. Res. 103, 20797 20811, 1998]. Despite significant data spread, the agreement can be qualified as reasonable for a data set comprising of 149 satellite passes over the Northern Hemisphere at high latitudes. The slope of the best-fit line relating SuperDARN and DMSP velocity magnitudes is of the order of 0.3 with a tendency for the SuperDARN velocities to be smaller. The agreement between the azimuths of the ion drift and convection is better with the slope of the best-fit line being close to 1. It is shown that consistency between the radar and satellite measurements is much better if the SuperDARN line-of-sight velocities are compared with the DMSP cross-track ion drifts for events showing slow spatial and temporal variations of the convection. If areas of strong convection changes are included into comparison, the degree of agreement deteriorates drastically. This result implies that differences in the spatial and temporal resolutions of DMSP and SuperDARN measurements are crucial factors contributing to the observed discrepancies. In addition, some differences are introduced when the SuperDARN line-of-sight velocities are filtered and reprocessed into vectors with the application of a background convection model.

  6. Ionospheric signatures of plasma injections in the cusp triggered by solar wind pressure pulses

    E-print Network

    California at Berkeley, University of

    Ionospheric signatures of plasma injections in the cusp triggered by solar wind pressure pulses pressure pulses. In association with each of these pulses, Cluster observes plasma injections while auroral dynamic pressure pulses are the drivers of plasma injections from the magnetosheath into the cusp; (2

  7. Direct evidence of double-slope power spectra in the high-latitude ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Spicher, A.; Miloch, W. J.; Moen, J. I.

    2014-03-01

    We report direct observations of the double-slope power spectra for plasma irregularities in the F layer of the polar ionosphere. The investigation of cusp irregularities ICI-2 sounding rocket, which was launched into the polar cusp ionosphere, intersected enhanced plasma density regions with decameter-scale irregularities. Density measurements at unprecedented high resolution with multi-Needle Langmuir Probes allowed for a detailed study of the plasma irregularities down to kinetic scales. Spectral analysis reveals double-slope power spectra for regions of enhanced fluctuations associated mainly with density gradients, with the steepening of the spectra occurring close to the oxygen gyrofrequency. These findings are further supported with the first results from the ICI-3 rocket, which flew through regions with strong precipitation and velocity shears. Previously, double-slope spectra have been observed in the equatorial ionosphere. The present work gives a direct evidence that the double-slope power spectra can be common in the high-latitude ionosphere.

  8. A climatological assessment of ionospheric travelling convection vortices using an automatic detection algorithm

    NASA Astrophysics Data System (ADS)

    Kotsiaros, S.; Stolle, C.; Friis-Christensen, E. A.; Matzka, J.

    2013-12-01

    Analysis of geomagnetic variometer data from the Greenland magnetometer array shows signatures of localized ionospheric travelling convection vortices (TCVs), which are commonly believed to be generated by compression or decompression of the magnetopause by changes in the solar wind dynamic pressure, flux transfer events, or magnetospheric Kelvin-Helmholtz instabilities. We present an algorithm for automatic detection of TCVs in Greenland magnetic data which is based on the short-time-average through long-time-average trigger (STA/LTA), an algorithm broadly used in weak-motion seismology. Results of their climatological assessment of their occurrence properties are discussed. In this paper, three years of magnetometer data, from 2010 to 2013, collected at twelve stations at the West coast of Greenland are analysed and TCV events are classified with respect to their intensity, duration and time of occurrence. Subsequently, they are correlated with values of the interplanetary magnetic field (IMF), solar wind velocity and geomagnetic indices. The results indicate that TCVs occur usually around magnetic local noon with a typical duration of approximately 15 to 30 minutes. TCV detection is clearly facilitated during times of low geomagnetic background activity.

  9. 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.

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

    SciTech Connect

    Tang, Wenbo, E-mail: Wenbo.Tang@asu.edu; Mahalov, Alex, E-mail: Alex.Mahalov@asu.edu [School of Mathematical and Statistical Sciences, Arizona State University, Tempe, Arizona 85287 (United States)] [School of Mathematical and Statistical Sciences, Arizona State University, Tempe, Arizona 85287 (United States)

    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.

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

    NASA Astrophysics Data System (ADS)

    Tang, Wenbo; Mahalov, Alex

    2014-04-01

    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.

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

    SciTech Connect

    Kopnin, S. I. [Institute for Dynamics of Geospheres, RAS, Moscow 119334 (Russian Federation); Popel, S. I. [Institute for Dynamics of Geospheres, RAS, Moscow 119334 (Russian Federation); Space Research Institute, RAS, Moscow 117997 (Russian Federation); Yu, M. Y. [Department of Physics, Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027, China and Institute for Theoretical Physics I, Ruhr University, D-44780 Bochum (Germany)

    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.

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

    Microsoft Academic Search

    Rickard Lundin; Bengt Hultqvist

    1989-01-01

    The measurements of electric fields and the composition of upward flowing ionospheric ions (UFIs), obtained by Viking's Ion Composition Spectrometers are interpreted in terms of a mass-dependent plasma escape process in the upper ionosphere. Results on the temperature and mass-composition of UFI beams suggest that the beams can be generated by a magnetic moment 'pumping' mechanism caused by low-frequency transverse

  14. 3D Global MHD Simulation of the Saturn Magnetospheric Plasma Interaction with Titan's Ionosphere

    Microsoft Academic Search

    Yingjuan Ma; A. F. Nagy; T. E. Cravens; G. Toth; F. J. Crary; A. J. Coates; M. K. Dougherty

    2006-01-01

    The interaction between Titan's ionosphere and its surrounding plasma is simulated using our 3D multi-species MHD model.We compare the simulation results with the observations obtained during the T9 flyby, using the upstream plasma parameters measured during the flyby. The Hall term (JXB) is also included in the model to investigate the ion gyro-radii effect.

  15. Studies of HF-induced Strong Plasma Turbulence at the HAARP Ionospheric Observatory

    Microsoft Academic Search

    J. P. Sheerin; N. Adham; R. G. E. Roe; M. R. Keith; B. J. Watkins; W. A. Bristow; P. A. Bernhardt; C. A. Selcher

    2010-01-01

    High power HF transmitters may induce a number of plasma instabilities in the interaction region of overdense ionospheric plasma. We report results from our recent experiments using over one gigawatt of HF power (ERP) to generate and study strong Langmuir turbulence (SLT) and particle acceleration at the HAARP Observatory, Gakona, Alaska. Among the effects observed and studied in UHF radar

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

    SciTech Connect

    Friis-Christensen, E.; McHenry, M.A.; Clauer, C.R.; Vennerstroem, S.

    1988-03-01

    Analysis of 20-second resolution magnetometer data from an array of temporary stations operated around Soendre Stroemfjord, 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 current 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. copyright American Geophysical Union 1988

  17. 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.

  18. 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.

  19. Lifetime of a depression in the plasma density over Jicamarca produced by space shuttle exhaust in the ionosphere

    Microsoft Academic Search

    E. Kudeki; L. Condori; F. Villanueva

    2001-01-01

    When the space shuttle orbiting maneuver subsystem (OMS) engines burn in the ionosphere, a plasma density depression, or ``hole,'' is produced. Charge exchange between the exhaust molecules and the ambient O+ ions yields molecular ion beams that eventually recombine with electrons. The resulting plasma hole in the ionosphere can be studied with ground-based, incoherent scatter radars (ISRs). This type of

  20. Observations of the Topside Ionosphere Plasma Bubbles in the Separate Plasma Component (He+): Model Estimations

    NASA Astrophysics Data System (ADS)

    Sidorova, Larisa; Filippov, Sergey

    2013-04-01

    The question about an opportunity to detect the topside plasma bubbles of equatorial origin in their separate plasma component (He+) is investigated. There are the indications [1, 2, 3, 4] that there is genetic connection between the He+ density depletions (subtroughs) and the equatorial plasma bubbles. For validation of this idea the characteristic times of the main aeronomy and electrodynamics processes, in which the plasma bubbles and their minor ion component (He+) are involved, have been calculated and compared among themselves. The conditions and factors, connected with solar activity, which are more favorable in the detection of the topside ionosphere plasma bubbles as He+ depletions, were under consideration. The numerical calculations, obtained in SAMIS3 model (3D model of equatorial spread F) and kindly presented by J. Huba (USA) [5], were used for this study. It was revealed that the plasma bubbles, reaching the "ceiling" heights, can exist within several days and that there is principal opportunity to observe them in the separate plasma component (He+). [1] L.N. Sidorova, Adv. Space Res. 33, 850 (2004). [2] L.N. Sidorova, Adv. Space Res. 39, 1284 (2007). [3] L.N. Sidorova, Geomag. and Aeronomy, Intern. 48, 56 (2008). [4] L.N. Sidorova, S.V. Filippov, J. Atm. Solar-Terr. Phys. 86, 83-91, doi: 10.1016/j.jastp.2012.06.013 (2012). [5] J.D. Huba, G. Joyce, J. Krall, Geophys. Res. Lett. 35, L10102, doi:10.1029/2008GL033509 (2008).

  1. Convective transport of plasma in the inner Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

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

    1990-04-01

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

  2. Dayside ionospheric convection changes in response to long-period interplanetary magnetic field oscillations - Determination of the ionospheric phase velocity

    NASA Technical Reports Server (NTRS)

    Saunders, M. A.; Freeman, M. P.; Southwood, D. J.; Cowley, S. W.; Lockwood, M.; Samson, J. C.; Farrugia, C. J.; Hughes, T. J.

    1992-01-01

    Ground magnetic field perturbations recorded by the CANOPUS magnetometer network in the 7 to 13 MLT sector are used to examine how reconfigurations of the dayside polar ionospheric flow take place in response to north-south changes of the IMF. During the 6-h interval in question, IMF Bz oscillates between +/- 7 nT with about a 1-h period. Corresponding variations in the ground magnetic disturbance are observed which we infer are due to changes in ionospheric flow. Cross correlation of the data obtained from two ground stations at 73.5 deg magnetic latitude, but separated by about 2 hours in MLT, shows that changes in the flow are initiated in the prenoon sector (about 10 MLT) and then spread outward toward dawn and dusk with a phase speed of about 5 km/s over the longitude range about 8 to 12 MLT, slowing to about 2 km/s outside this range. Cross correlating the data from these ground stations with IMP 8 IMF Bz records produces a MLT variation in the ground response delay relative to the IMF which is compatible with these deduced phase speeds.

  3. 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.

  4. Electrodynamic tether currents in the day/night ionosphere: Correlations during the Plasma Motor Generator mission

    NASA Astrophysics Data System (ADS)

    Wilson, Thomas L.; Chlouber, Dean; Jost, R. Jerry

    1996-10-01

    Ground-based radar observations during NASA's Plasma Motor Generator (PMG) electrodynamic tether mission are reported, which indicate the existence of ion-acoustic or soliton wave packets produced as ionospheric excitations by the orbiting PMG tether system. These appear to be the first such radar measurements of traveling ionospheric disturbances propagating along geomagnetic field lines during an active orbiting ionospheric tether-plasma experiment. The presence of such excitations gives added importance to earlier studies of the plasma radiation modes involved in tether electrodynamics and the part they play in the ionospheric energy balance mechanisms. In addition, tether-current measurements studied during postflight data analysis show a pronounced current decrease when the spacecraft passed from daylight to darkness, which may be related to current limiting. The significance of this observed day/night correlation in conjunction with the soliton-like wave packet radiation modes calls for a detailed investigation of the PMG tether-current measurements in terms of local and global interactions of the PMG with Earth's ionosphere, the initial work for which we show here. This includes an analysis of the radiation impedance due to Alfvén and lower hybrid bands, ion-acoustic (soliton) modes, and whistler waves. A decomposition of the measured tether currents into Hall, Pedersen, Cowling, and Birkeland conductivities is presented.

  5. 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.

  6. Synthesis of various ionospheric convection patterns for IMF BY-dominated periods: Split crescent cells, exchange cells, and theta aurora formation

    Microsoft Academic Search

    Masakazu Watanabe; George J. Sofko

    2008-01-01

    When the dawn-to-dusk component of the interplanetary magnetic field (IMF BY) is dominant, ionospheric convection exhibits a distorted two-cell pattern with its dawn-dusk and interhemispheric asymmetries regulated by the IMF BY polarity. For BY > 0, the convection in the Northern (Southern) Hemisphere usually consists of a relatively round cell on the duskside (dawnside) and a crescent-shaped cell on the

  7. 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.

  8. 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

  9. 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.

  10. Convective transport in laser target plasmas

    SciTech Connect

    Brackbill, J.U.; Colombant, D.; Grandjouan, N.

    1982-01-01

    The role of guiding-center corrections in convective transport of electron energy is examined with a simple numerical model. At 10/sup 16/W cm/sup -2/ with a 60-..mu..m spot and a 10.6-..mu..m wavelength laser, the Righi-Leduc term is observed to have little effect on transport in a calculation with the thermal flux limited to the free-streaming value.

  11. 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.

  12. A PLASMA INSTABILITY RESULTING IN FIELD-ALIGNED IRREGULARITIES IN THE IONOSPHERE

    Microsoft Academic Search

    D. T. Farley; D. T. Jr

    1963-01-01

    A theory of the two-stream ion wave instability in a plasma is developed ; that takes into account both the effect of collisions of the ions and electrons ; with neutral particles and the presence of a uniform magnetic field. Applying ; the results to the ionosphere, it is found that irregularities of ionization ; density should arise spontaneously in

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

    Microsoft Academic Search

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

    2010-01-01

    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

  14. 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.

  15. High-frequency spontaneous emission of an electron beam injected into the ionospheric plasma

    Microsoft Academic Search

    J. Lavergnat; R. Pellat

    1979-01-01

    This paper gives a detailed quantitative analysis of the high-frequency spontaneous wave emissions produced by an electron beam injected into the ionospheric plasma. A general discussion about individual-collective and incoherent-coherent characteristics of the emissions is given. Then attention is focused on the spontaneous coherent emission in three different modes: plasma waves, Bernstein modes, and electromagnetic whistler mode. Comparisons with experimental

  16. 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.

  17. A modelling study of the latitudinal variations in the nighttime plasma temperatures of the equatorial topside ionosphere during

    E-print Network

    Paris-Sud XI, Université de

    of the equatorial topside ionosphere during northern winter at solar maximum G. J. Bailey1 , M. H. Denton1 , R. A in the nighttime plasma temperatures of the equatorial topside ionosphere dur- ing northern winter at solar maximum®rm that the crests observed near 15 latitude in the winter hemisphere are due to adiabatic heating and the troughs

  18. Modeling the low-latitude ionospheric electron density and plasma turbulence in the November 2004 storm period

    Microsoft Academic Search

    J. M. Retterer; Ronald Ilma; M. C. Kelley; Jorge L. Chau; C. E. Valladares; L. C. Gentile; K. Groves

    2010-01-01

    The storm period of 8-12 November 2004 offers an opportunity for insight into the phenomena of low-latitude ionospheric structure during geomagnetically disturbed times because of the strength of the disturbances, the timing of the storms, and the instrumentation that was operating during the interval. We will take advantage of these factors to model the ambient ionosphere and the plasma turbulence

  19. Modeling the low-latitude ionospheric electron density and plasma turbulence in the November 2004 storm period

    Microsoft Academic Search

    J. M. Retterer; Ronald Ilma; M. C. Kelley; Jorge L. Chau; C. E. Valladares; L. C. Gentile; K. Groves

    2010-01-01

    The storm period of 8–12 November 2004 offers an opportunity for insight into the phenomena of low-latitude ionospheric structure during geomagnetically disturbed times because of the strength of the disturbances, the timing of the storms, and the instrumentation that was operating during the interval. We will take advantage of these factors to model the ambient ionosphere and the plasma turbulence

  20. 34th EPS Plasma Physics, Warsaw, Poland, 2--7 July, 2007 Nonlinear physics of the ionosphere

    E-print Network

    34th EPS Plasma Physics, Warsaw, Poland, 2--7 July, 2007 Nonlinear physics of the ionosphere Space Centre, Växjö #12;Bo Thidé 34th EPS Plasma Physics, Warsaw, Poland, 2--7 July, 20072 Space plasma diagnostic. #12;Bo Thidé 34th EPS Plasma Physics, Warsaw, Poland, 2--7 July, 20073 Secondary radiation

  1. Comparisons Between In-Situ Plasma Fluctuation and Radio Occultation Based Measures of Ionospheric Scintillation

    NASA Astrophysics Data System (ADS)

    Straus, P. R.; Roddy, P. A.; Bonito, N.

    2010-12-01

    Ionospheric radio occultation (RO) and in-situ measurements of plasma density fluctuations provide two different approaches for inferring the presence or absence of ionospheric scintillation. The RO technique involves a direct measure of scintillation at L-band frequencies, but in a limb-viewing geometry that entails some uncertainty regarding the precise geolocation of the associated irregularity region or regions. Scintillation over a range of frequencies from UHF to L-band can be inferred from observation of the in-situ irregularity spectrum together with a set of modeling assumptions. The CORISS (C/NOFS Occultation Receiver for Ionospheric Sensing and Specification) and PLP (Planar Langmuir Probe) instruments on board the C/NOFS satellite provide a means to compare and contrast the two approaches in a rigorous manner. This presentation with report initial comparison results based on data collected during the 2008-2010 time frame.

  2. Dust Acoustic Solitons in the Dusty Plasma of the Earth's Ionosphere

    SciTech Connect

    Kopnin, S.I.; Kosarev, I.N.; Popel, S.I. [Institute of Geosphere Dynamics, Russian Academy of Sciences, Leninskii pr. 38-1, Moscow, 119334 (Russian Federation); Yu, M.Y. [Institute for Theoretical Physics I, Ruhr University Bochum, D-44780 Bochum (Germany)

    2005-03-15

    Stratified structures that are observed at heights of 80-95 km in the lower part of the Earth's ionosphere are known as noctilucent clouds and polar mesosphere summer echoes. These structures are thought to be associated with the presence of vast amounts of charged dust or aerosols. The layers in the lower ionosphere where there are substantial amounts of dust are called the dusty ionosphere. The dust grains can carry a positive or a negative charge, depending on their constituent materials. As a rule, the grains are ice crystals, which may contain metallic inclusions. A grain with a sufficiently large metallic content can acquire a positive charge. Crystals of pure ice are charged negatively. The distribution of the dust grains over their charges has a profound impact on the ionizational and other properties of dust structures in the dusty ionosphere. In the present paper, a study is made of the effect of the sign of the dust charge on the properties of dust acoustic solitons propagating in the dusty ionosphere. It is shown that, when the dust charge is positive, dust acoustic solitons correspond to a hill in the electron density and a well in the ion density. When the dust is charged negatively, the situation is opposite. These differences in the properties of dust acoustic solitons can be used to diagnose the plasmas of noctilucent clouds and polar mesosphere summer echoes.

  3. 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

  4. Simultaneous observations of convective ionospheric storms: ROCSAT-1 and ground-based imagers

    Microsoft Academic Search

    J. J. Makela; M. C. Kelley; S.-Y. Su

    2005-01-01

    The irregularities that occur in the postsunset equatorial ionosphere are one of the most spectacular effects of space weather. They occur over many decades of scale sizes and can cause scintillation of signals transmitted on a wide range of frequencies used by satellite communication and navigation systems, rendering such systems inoperable for a period of time. In the near future,

  5. Plasma convection at high latitudes using the EISCAT VHF and ESR incoherent scatter radars

    E-print Network

    Boyer, Edmond

    Plasma convection at high latitudes using the EISCAT VHF and ESR incoherent scatter radars J. M allows several important tests to be made on the determination of convection patterns from incoherent volume results from the two radars are compared. The plasma convection velocities determined

  6. Long time scale evolution of high-power radio wave ionospheric heating 1. Beam propagation

    Microsoft Academic Search

    M. J. Keskinen; P. K. Chaturvedi; S. L. Ossakow

    1993-01-01

    The long time scale evolution, that is, for times long compared to an electron collision period of high-power radio wave ionospheric heating, is studied. Preliminary studies are made to model high-power radio wave propagation in an ionosphere containing a dynamically produced electron density cavity. We show that high-power radio wave-induced plasma density depletions in the F region ionosphere will convect

  7. Long time scale evolution of high-power radio wave ionospheric heating. 1. Beam propagation

    Microsoft Academic Search

    M. J. Keskinen; P. K. Chaturvedi; S. L. Ossakow

    1993-01-01

    The long time scale evolution, that is, for times long compared to an electron collision period of high-power radio wave ionospheric heating, is studied. Preliminary studies are made to model high-power radio wave propagation in an ionosphere containing a dynamically produced electron density cavity. We show that high-power radio wave-induced plasma density depletions in the F region ionosphere will convect

  8. Could global warming affect space weather? : case studies of intense ionospheric plasma turbulence associated with natural heat sources

    E-print Network

    Pradipta, Rezy

    2007-01-01

    We report on observations of a series of highly-structured ionospheric plasma turbulence over Arecibo on the nights of 22/23 and 23/24 July, 2006. Incoherent scatter measurements by Arecibo radar, airglow measurements using ...

  9. 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.

  10. 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.

  11. Self-consistent ionospheric plasma density modifications by field-aligned currents: Steady state solutions

    NASA Astrophysics Data System (ADS)

    Russell, A. J. B.; Wright, A. N.; Hood, A. W.

    2010-04-01

    The magnetosphere and ionosphere are coupled by field-aligned currents that remove or deposit E-region electrons. Changes in electron number density modify ionospheric reflectivity, hence altering the magnetospheric current. Thus, self-consistent solutions are nontrivial. In this paper, we present 1-D steady states that self-consistently model modifications of ionospheric plasma density by field-aligned currents. These are used to investigate the width broadening and minimum plasma density of E-region plasma density cavities and the origin of small-scale features observed in downward current channels. A plasma density cavity forms and broadens if the maximum initial current density j$\\parallel$0 exceeds jc = ?ne2he/(1 + 1/?), where ? is the recombination coefficient, ne is the equilibrium E-region number density in the absence of currents, h is the E-region thickness, and ? = $\\SigmaP0/\\Sigma_{A is the initial ratio of Pedersen to magnetospheric Alfvén conductivities. If a plasma density cavity forms, its final width increases monotonically with $\\cal{W = 2B0/?0VA?ne2he, where B0 is the background magnetic field strength and VA is the magnetospheric Alfvén speed. The minimum E-region number density, and the finest length scale present in the steady state, both scale as 1/?. For typical ionospheric parameters and j$\\parallel$0 = 5 ?Am-2, the fine scale is comparable to or less than 6?e for ? $\\gtrsim$ 2, where ?e is the electron inertial length. This suggests that electron inertial effects may become significant and introduce small-scale features, following the production of a single fine scale by depletion and broadening.

  12. Solar Plasma Flows and Convection in Oblique Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Smith, Christina; Zita, E. J.; Hurlburt, Neal

    2010-10-01

    Moving charges in the Sun's plasma create a complex network of magnetic fields. This is at the heart of dynamic solar events, such as active regions, sunspots, and coronal mass ejections. We study magnetoconvection, the motion of magnetized ionized fluids (plasmas), to better understand the Sun. Models of solar magnetoconvection often assume simplified magnetic fields that are either completely vertical or horizontal. Realistic fields, however, are often inclined at oblique angles. We analyze high resolution data from the Solar Optical Telescope on the Hinode spacecraft, and compare velocities with magnetic field inclinations. We then compare results with predictions from a numerical model of nonlinear compressible convection in oblique magnetic fields.

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  16. Morphology of the postsunset vortex in the equatorial ionospheric plasma drift

    NASA Astrophysics Data System (ADS)

    Lee, Woo Kyoung; Kil, Hyosub; Kwak, Young-Sil; Paxton, Larry J.

    2015-01-01

    postsunset vortex in the equatorial ionosphere exhibits clockwise plasma motions after sunset in longitude (time) and altitude coordinates when the equatorial ionosphere is viewed looking northward. We describe the typical morphology of the postsunset vortex using incoherent scatter radar observations at Jicamarca in Peru during the previous solar maximum (2000-2002). A pronounced vortical plasma motion appears around 1700 LT along with the onset of the prereversal enhancement (PRE). The center of this vortex is located near an altitude of 270 km. A smaller-scale vortex also appears about 0.5 ~ 1 h later at higher altitudes. However, the morphology and occurrence time of this small vortex depend on the characteristics of the coherent backscatter region. We find that the earlier vortex is the major feature of the postsunset vortices because it is repeatable, associated with the PRE, and independent to the occurrence of the coherent backscatter region.

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

    SciTech Connect

    Kopnin, S. I.; Morzhakova, A. A.; Popel, S. I. [Russian Academy of Sciences, Institute of Geosphere Dynamics (Russian Federation); Shukla, P. K. [Ruhr University Bochum (Germany)

    2011-08-15

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

  18. 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.

  19. 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.

  20. 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.

  1. Nonlinear evolution of modified two-stream instability above ionosphere of Titan: Comparison with the data of the Cassini Plasma Spectrometer

    Microsoft Academic Search

    Zoltán Dóbé; Karoly Szego; Kevin B. Quest; Vitali D. Shapiro; R. E. Hartle; E. C. Sittler

    2007-01-01

    The ionosphere of Titan, moon of Saturn, is directly exposed to the streaming plasma either of magnetospheric or solar wind origin. A turbulent interaction region is formed, called here flowside plasma mantle, where both cold ionospheric and hot streaming plasma are present at comparable densities. Within the framework of a one-dimensional electromagnetic hybrid simulation using realistic electron mass we have

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. Plasma disturbances observed in the ionosphere in the vicinity of a highly charged space vehicle

    SciTech Connect

    Maehlum, B.N.; Denig, W.F.; Friedrich, M.; Torkar, K.M.; Svenes, K.

    1990-01-01

    A mother-daughter rocket code named MAIMIK was launched from Andoya Rocket Range on November 10, 1985, near 20.0 local time. The daughter carried an electron accelerator, and a series of plasma diagnostic instruments were installed both on the daughter and the trailing mother. The main aims of the experiment were to investigate (i) beam-plasma interaction processes in the ionosphere, (ii) occurrence of DC and AC electric fields generated by the beam, and (iii) charging and neutralization of the vehicles.

  4. 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.

  5. Irregular magnetic pulsations in the polar cleft caused by traveling ionospheric convection vortices

    Microsoft Academic Search

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

    1988-01-01

    Irregular magnetic pulsations with periods of 5-8 minutes analyzed using data from an array of temporary stations around Sondre Stromfjord, Greenland have been found to correspond to traveling convection vortices. The vortices can be sorted into different classes corresponding to the following types: (1) isolated twin vortices, (2) single vortices, and (3) multiple vortices. The vortices are observed in the

  6. Floating potentials and the hot plasma generated by an electron-beam-emitting rocket in the ionosphere

    SciTech Connect

    Winckler, J.R.

    1983-01-01

    This paper summarizes some recent experimental results concerning the potentials of a large vehicle emitting a powerful electron beam in the ionosphere. Many such experiments have been conducted in the last decade (see Winckler 1) and these experiments indicate that if a constant electron beam is emitted in the ionosphere from a large rocket or other space vehicle, a return current may be drawn from the ionospheric plasma that will stabilize the potential of the vehicle in the range of a few tens of volts to perhaps several hundred volts.

  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. Linear mode conversion in inhomogeneous magnetized plasmas during ionospheric

    E-print Network

    Rubloff, Gary W.

    near the reflection layer of the ordinary mode are studied using one-dimensional (1-D) and two- dissipative instability [Borisov et al., 1977], super-heating instability [Polyakov and Yakhno, 1980], and self-focusing instability of plasma waves in the reflection region due to parametric instabilities

  9. 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.

  10. 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.

  11. 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.

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

    Microsoft Academic Search

    D. F. DuBois; Rose H. A; David Russell

    1990-01-01

    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)

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

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

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

  14. 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.

  15. Manifestation of the cotton-mouton effect in the ionosphere plasma

    NASA Astrophysics Data System (ADS)

    Kravtsov, Yu. A.; Naida, O. N.

    Polarization methods used to sound ionospheric plasma are based on the Faraday and Cotton-Mouton effects. While the Faraday effect (rotation of the polarization plane) covers almost the entire ray path, the Cotton-Mouton effect gives rise to local transformation of circularly polarized waves near a point of orthogonality of the ray and the Earth's magnetic field. Comparison of the input and output polarization of probing electromagnetic waves, emitted by a satellite and received by ground stations, can provide valuable information about local plasma parameters near the orthogonality point. This paper presents a theory of interaction of circular waves near this point based on the quasi-isotropic approximation (QIA) of geometrical optics and describes algorithms that can be used to retrieve local plasma parameters from polarization measurements. Experimental configurations to observe the Cotton-Mouton effect with linearly and arbitrarily polarized receivers are discussed.

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

    SciTech Connect

    Shimoyama, M.; Yau, A. W. [Department of Physics and Astronomy, University of Calgary, Calgary T2N1N4 (Canada); Oyama, K.-I. [Plasma and Space Science Center, National Cheng Kung University, Tainan 701, Taiwan (China); Abe, T. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa 252-5210 (Japan)

    2011-07-15

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

  17. Monitoring ionospheric plasmas in space weather context via DSLP observations on board Proba-2

    NASA Astrophysics Data System (ADS)

    Travnicek, Pavel; Stverak, Stepan; Hercik, David; Pavelka, Roman

    2014-05-01

    The experiment Dual Segmented Langmuir Probe (DSLP) on board Proba-2 spacecraft (ESA) provides a long-term continual survey of basic plasma properties measured in situ in the dawn and dusk sectors of the upper terrestrial ionosphere. DSLP observations are acquired by two identical segmented spherical Langmuir probes representing a novel approach to a well developed plasma diagnostic technique. Starting its nominal operations in May 2010 almost four years of regular observations are currently being available providing a substantial data set for monitoring observed ionospheric disturbances and irregularities in view of potential space weather drivers. Here we present initial DSLP data scientific applications including seasonal or immediate variations of derived plasma properties in comparison with possible effects of sudden solar events or long term trends in the overall solar activity. In addition we present an on-line data archive build on complete DSLP data set where all raw measurements are routinely being processed into calibrated higher level data products derived from the PDS and CDF standards and made available throughout web interface.

  18. On the maintenance of the Venus nightside ionosphere - Electron precipitation and plasma transport

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    The relative contributions of electron precipitation and transport of dayside plasma to the maintenance of the Venus nightside ionosphere during the long Venusian night are investigated based on simultaneous Pioneer Venus Orbiter Retarding Potential Analyzer measurements of suprathermal electron fluxes and plasma densities. In about 20 orbits, the nightside integral electron flux of electrons with energies between 5 and 45 eV is observed to be relatively constant in time and altitude, while plasma density is observed to vary by a factor of 10 or more with no correlation with the electron flux. Ionization rates and ion density height profiles are computed for O(+) and O2(+) as a function of magnetic dip angle based on a typical electron spectrum, or a downward flux of O(+) ions. Comparison of the computed profiles with the measured median O(+) and O2(+) density profiles reveals that the measured profiles can only be reproduced by a downward flux of O(+) equal to about 10 to the 8th/sq cm per sec; suprathermal electron energy distributions produce O2(+) and O(+) levels only about half and one tenth those usually observed, respectively. It is thus concluded that transport of O(+) ions from the dayside Venus ionosphere is responsible for approximately 75% of the typical nightside ionization, with variations in O(+) transport mechanism responsible for most of the observed nightside density variations. The remaining ionization is attributed to suprathermal electrons, which contribute principally to the O2(+) peak.

  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. 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.

  1. Magnetospheric interaction with Triton's ionosphere

    NASA Technical Reports Server (NTRS)

    Strobel, Darrell F.; Cheng, Andrew F.; Summers, Michael E.; Strickland, Douglas J.

    1990-01-01

    The large electron densities measured by the Voyager radio occultation experiment are attributed to the precipitation of magnetospheric electrons with energy above 10 keV. Because the ionospheric electric Pedersen conductivity of Triton is about 10,000-20,000 mho and the Alfven conductance is about 3.5 mho, direct convective flow of plasma into the essentially infinitely conducting ionosphere is negligible. Magnetospheric electrons are transported to Triton's ionopause by curvature drift as a result of weak magnetic field line draping in a sub-Alfvenic plasma interaction with Triton. At the ionopause energetic electrons have a high probability of elastic and inelastic scattering and precipitate into the upper atmosphere. The average power dissipation is estimated to be about (2 - 3) x 10 to the 8th W.

  2. Properties of convective cells generated in magnetized toroidal plasmas

    SciTech Connect

    Theiler, C.; Loizu, J.; Furno, I.; Fasoli, A.; Ricci, P. [Centre de Recherches en Physique des Plasmas-Ecole Polytechnique Federale de Lausanne (EPFL), Association EURATOM-Confederation Suisse, CH-1015 Lausanne (Switzerland)

    2012-08-15

    Convective cells for turbulence control, generated by means of biased electrodes, are investigated in the simple magnetized toroidal plasmas of TORPEX. A two-dimensional array of 24 electrodes is installed on a metal limiter to test different biasing schemes. This allows influencing significantly both radial and vertical blob velocities. It is shown that these changes agree quantitatively with the flows deduced from the time averaged potential perturbations induced by the biasing. Detailed measurements along and across the magnetic field provide a rather clear picture of the effect of biasing on time averaged profiles. The biased electrodes produce perturbations of the plasma potential and density profiles that are fairly uniform along the magnetic field. Background flows influence the location where potential variations are induced. The magnitude of the achievable potential variations in the plasma is strongly limited by cross-field currents and saturates at large bias voltages once the electrodes draw electron saturation current. A quantitative discussion on the origin of cross-field currents is presented, considering contributions related with diamagnetic drifts, ion inertia, collisions with neutrals, and viscosity.

  3. Plasma turbulence in the ionosphere prior to earthquakes, some remarks on the DEMETER registrations

    NASA Astrophysics Data System (ADS)

    B??cki, Jan; Parrot, Michel; Wronowski, Roman

    2011-06-01

    The question about presence of some precursors of the earthquakes has a long history. The answer is still not resolved, but researchers are looking for the effects which can be registered prior to earthquakes. One of the factors which has been found is the variation of the electromagnetic field observed on ground as well as onboard satellites. The disturbances of the electromagnetic field around areas of the earthquakes as pre-seismic events can occur few hours or even few days before the main shock. The payload of the DEMETER French microsatellite allows to measure waves and also some important plasma parameters (ion composition, electron density and temperature, energetic particles) with high temporal resolution in the ionosphere over the seismic regions. In the present work, analysis of the low frequency fluctuations of the electric fields for selected strong earthquakes in Japan (2004), China (2008), Taiwan (2006) and New Zealand (2009) are given. Special attention will be given to the study of the spectral characteristics of these variations and the search for nonlinear effects. This analysis is possible in the time interval where the waveform has been transmitted. The mechanism of the energy transmission from earthquakes to the ionosphere is not clear, but we can discuss the behavior of the ionospheric plasma and the search for instabilities which could be a source of electromagnetic field variations. A brief discussion of the characteristics of the spectra and multi-spectra is given in this paper. Attention is particularly given to the effect prior to the earthquake in New Zealand, when a nonlinear interaction leading to a lower hybrid wave generation was directly seen.

  4. 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.

  5. Study of the Excitation Conditions and Characteristics of Ionospheric Plasma Turbulence at the Development Stage of the Ponderomotive Parametric Instability

    NASA Astrophysics Data System (ADS)

    Sergeev, E. N.; Grach, S. M.; Kotov, P. V.

    2004-03-01

    We present the results of studying the development features of nonlinear effects at the initial stage of interaction of powerful HF radio waves with the plasma in the ionospheric F region. Experimental measurements were performed at the ``Sura'' heating facility for a wide pump frequency range (4.5-9.0 MHz) and a variety of pulse durations (0.3-100 ms) and effective radiated powers (1-30 MW) at various times of a day. The performed measurements allow us to study the excitation thresholds and time-amplitude characteristics of the ponderomotive self-action of a pump wave as well as the relaxation characteristics of the stimulated electromagnetic emission of the ionosphere as functions of the pump parameters and ionospheric conditions. The measured development features of the ponderomotive parametric instability in the ionospheric plasma are compared with the calculation results. The instability threshold fields (Eth~ 220 mV/m) and the damping rates (?e~ 450 s-1) of plasma waves, measured under evening-time conditions, are close to the estimates obtained on the assumption of collisional damping of Langmuir turbulence. A significant increase in the threshold field and the damping rate (by factors of up to 3 and 6, respectively) was observed under daytime conditions. In this case, the minimum values of these quantities (Eth~ 350 mV/m and ?e~ 600 s-1) were observed for pump-wave reflection heights of about z~ 230 km. The measurement and simulation results are indicative of the dominant effect of photoelectrons on the development features of ionospheric plasma turbulence under daytime conditions. We discuss the possibilities of using the developed method for comprehensive monitoring of the parameters of Langmuir turbulence and the background ionospheric plasma.

  6. 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.

  7. Modeling storm-time electrodynamics of the low-latitude ionosphere–thermosphere system: Can long lasting disturbance electric fields be accounted for?

    Microsoft Academic Search

    Naomi Maruyama; Stanislav Sazykin; Robert W. Spiro; David Anderson; Adela Anghel; Richard A. Wolf; Frank R. Toffoletto; Timothy J. Fuller-Rowell; Mihail V. Codrescu; Arthur D. Richmond; George H. Millward

    2007-01-01

    Storm-time ionospheric disturbance electric fields are studied for two large geomagnetic storms, March 31, 2001 and April 17–18, 2002, by comparing low-latitude observations of ionospheric plasma drifts with results from numerical simulations based on a combination of first-principles models. The simulation machinery combines the Rice convection model (RCM), used to calculate inner magnetospheric electric fields, and the coupled thermosphere ionosphere

  8. 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.

  9. Lifetime of a depression in the plasma density over Jicamarca produced by space shuttle exhaust in the ionosphere

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Huba, J. D.; Kudeki, E.; Woodman, R. F.; Condori, L.; Villanueva, F.

    2001-09-01

    When the space shuttle orbiting maneuver subsystem (OMS) engines burn in the ionosphere, a plasma density depression, or "hole," is produced. Charge exchange between the exhaust molecules and the ambient O+ ions yields molecular ion beams that eventually recombine with electrons. The resulting plasma hole in the ionosphere can be studied with ground-based, incoherent scatter radars (ISRs). This type of ionospheric modification is being studied during the Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) series of experiments over ISR systems located around the globe. The SIMPLEX 1 experiment occurred over Jicamarca, Peru, in the afternoon on October 4, 1997, during shuttle mission STS 86. An electron density depression was produced at 359 km altitude at the midpoint of a magnetic field line. The experiment was scheduled when there were no zonal drifts of the plasma so the modified field line remained fixed over the 50 MHz Jicamarca radar. The density depression was filled in by plasma flowing along the magnetic field line with a time constant of 4.5 min. The density perturbation had completely vanished 20 min after the engine burn. The experimental measurements were compared with two models: (1) SAMI2, a fully numerical model of the F region, and (2) an analytic representation of field-aligned transport by ambipolar diffusion. The computed recovery time from each model is much longer than the observed recovery time. The theory of ambipolar diffusion currently used in ionospheric models seems to be inadequate to describe the SIMPLEX 1 observations. Several possible sources for this discrepancy are discussed. The SIMPLEX 1 active experiment is shown to have the potential for testing selected processes in ionospheric models.

  10. 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.

  11. Variations in the ionospheric wave perturbation spectrum during periodic heating of the plasma by high-power high-frequency radio waves

    Microsoft Academic Search

    L. F. Chernogor; V. L. Frolov; G. P. Komrakov; V. F. Pushin

    2011-01-01

    We present the results of spectral analysis of temporal variations in the Doppler frequency shift of the ionosphere-reflected\\u000a signals from a high-frequency vertical ionospheric sounding radar located near the city of Kharkov in the days of exposure\\u000a of the ionospheric plasma to the high-power radio emission of the Sura facility (Nizhny Novgorod) and in the reference day\\u000a in the absence

  12. 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.

  13. Dynamics of the convection in the inner magnetosphere by observations of the diffuse aurora, SAR arc and ionospheric drift

    NASA Astrophysics Data System (ADS)

    Ievenko, I. B.; Stepanov, A. E.; Alexeyev, V. N.; Smirnov, V. F.

    Until recently in the literature the attention has been focused to a phenomenon which is called as a polarization jet Galperin et al 1974 or SAID subauroral ion drifts Spiro et al 1979 These are polar orbiting satellite observations of a narrow band of westward plasma drift at a height of F2 layer with a velocity up to 2 km s in the vicinity of plasmapause projection during substorms As a result of the last classification of data from the Millstone Hill incoherent scatter radar Foster and Vo 2002 it has been found that during geomagnetic disturbances at Kp ge 4 the westward plasma drift region equatorward of auroral precipitations in the MLT night sector has a latitudinal extent which is much more than in SAID Therein this phenomenon is called as a subauroral polarization stream SAPS The basic regularities of convection electric field penetration to plasmasphere latitudes at Kp 1-6 have been shown earlier as well as by data from the Millstone Hill incoherent scatter radar by Wand and Evans 1981 Lyatskaya and Kuznetsov 1990 found the relation of the height dynamics of the regular ionization layer F2 azimuth component of the electric field at middle latitudes to the increase of the IMF southern component The authors Ievenko et al 2001 obtained the recurring features of penetration of the convection electric field to plasmasphere latitudes in the dynamics of F2 layer ionization in the region of diffuse aurora DA and SAR arc during substorms Here we present the comparison results of subauroral luminosity dynamics in

  14. Lobe cell convection and field-aligned currents poleward of the region 1 current system

    Microsoft Academic Search

    S. Eriksson; J. W. Bonnell; L. G. Blomberg; R. E. Ergun; G. T. Marklund; C. W. Carlson

    2002-01-01

    We present a case and statistical study of plasma convection in the Northern Hemisphere during summer conditions using electric field, magnetic field, and particle data taken during dawn-dusk directed orbits of the FAST satellite. To our knowledge, this set provides the most comprehensive combination of data as yet presented in support of lobe cell convection from an ionospheric perspective this

  15. 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.

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

    SciTech Connect

    Istomin, Ya. N. [P. N. Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation)] [P. N. Lebedev Physical Institute, Leninsky Prospect 53, 119991 Moscow (Russian Federation); Leyser, T. B. [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden)] [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  19. Convective Cell Formation in a Z-Pinch Plasma Science and Fusion Center

    E-print Network

    Convective Cell Formation in a Z-Pinch J. Kesner Plasma Science and Fusion Center Massachusetts and the MHD time scales, 3 /(acs) with the thermal diffusivity, cs the sound speed and a the characteristic

  20. 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.

  1. 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.

  2. Large-Scale Plasma Structure in the Polar and Auroral Ionosphere: Experimental Observations and Modelling

    Microsoft Academic Search

    S. E. Pryse; H. R. Middleton; K. L. Dewis; A. G. Wood; E. L. Whittick; R. L. Balthazor

    Radiotomography provides observations of ionospheric electron density structure on horizontal scales of tens to hundreds of kilometres. Routine measurements over extended periods of time and geographic areas have the potential for parameterising the structure of the polar and auroral ionosphere. Averaged electron densities characteristic of different ionospheric features, locations, local times, Universal Times, seasons, geomagnetic activity and solar conditions can

  3. Investigation by backscatter radar of artificial irregularities produced in ionospheric plasma heating experiments

    Microsoft Academic Search

    N. V. Bakhmet'eva; V. N. Bubukina; Yu. A. Ignat'ev; G. S. Bochkarev; V. A. Eremenko; V. V. Kol'tsov; I. V. Krasheninnikov; Yu. N. Cherkashin

    1997-01-01

    The artificial ionospheric turbulence occurs in the ionosphere illuminated by high power HF radio waves. There are a lot of irregularities stretched along the geomagnetic field in this region. The investigation of the artificially disturbed ionospheric region is based on the reception of back scattered signals (BSS) which permits the basic parameters of this region to be estimated and its

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

    Microsoft Academic Search

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

    1980-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

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

    SciTech Connect

    Wiesenberger, M., E-mail: Matthias.Wiesenberger@uibk.ac.at; Kendl, A. [Institute for Ion Physics and Applied Physics, Association EURATOM-ÖAW, University of Innsbruck, A-6020 Innsbruck (Austria); Madsen, J. [Association EURATOM-DTU, Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark)

    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.

  7. 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.

  8. 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

  9. 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.

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

    SciTech Connect

    Kovaleva, I. Kh. [Russian Academy of Sciences, Institute of Geosphere Dynamics (Russian Federation)] [Russian Academy of Sciences, Institute of Geosphere Dynamics (Russian Federation)

    2013-03-15

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

  11. 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.

  12. Nonlinear evolution of modified two-stream instability above ionosphere of Titan: Comparison with the data of the Cassini Plasma Spectrometer

    NASA Astrophysics Data System (ADS)

    Dóbé, ZoltáN.; Szego, Karoly; Quest, Kevin B.; Shapiro, Vitali D.; Hartle, R. E.; Sittler, E. C.

    2007-03-01

    The ionosphere of Titan, moon of Saturn, is directly exposed to the streaming plasma either of magnetospheric or solar wind origin. A turbulent interaction region is formed, called here flowside plasma mantle, where both cold ionospheric and hot streaming plasma are present at comparable densities. Within the framework of a one-dimensional electromagnetic hybrid simulation using realistic electron mass we have shown that significant wave activity may be generated because of a modified two-stream instability (MTSI). Having its free energy in the relative drift between the streaming ion flow and the ionospheric ions MTSI is very effective in generating "anomalous viscosity" type interaction leading to significant bulk velocity loss of the proton component of the external plasma flow and turbulent heating of the ionospheric ions. The stochastic energy transfer from the streaming plasma to the ionospheric ions may also increase the tailward planetary ion escape by collective pickup mechanism enhancing the rate of erosion of the atmosphere of Titan. We predict significant wave activity within the characteristic frequency range of about 1-10 Hz and at saturated wave electric field levels of about 5-25 mV/m. Similarly, according to our model calculations superthermal charged particles of ionospheric origin with kinetic energies of about few tens of eV are expected to be detectable by the charged particle analyzers onboard of Cassini spacecraft close to the upper edge of Titan's ionosphere.

  13. 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.

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

    SciTech Connect

    Deng, Yongfeng, E-mail: yfdeng@mail.dlut.edu.cn; Han, Xianwei [Shaanxi Power Machine Design and Research Institute, Xi'an 710100 (China); Tan, Yonghua [Academy of Aerospace Propulsion Technology, Xi'an 710100 (China)

    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.

  15. Interaction of Venus and Titan with their Plasma Environments

    NASA Astrophysics Data System (ADS)

    Weil, H. Y.; Russell, C. T.; Dougherty, M. K.; Luhmann, J. G.; Zhang, T. L.; Delva, M.; Ma, Y. J.

    2007-08-01

    The ionospheres of Titan, Venus and Mars are magnetized by their interactions with flowing magnetized plasma corotating with Saturn in the former case and convected by the supersonic solar wind in the latter two cases. At solar maximum, the Venus ionosphere was found to be generally field-free by the PVO eccentric orbiter, albeit threaded with twisted flux ropes. Venus Express is now orbiting Venus at solar minimum and detects a largely magnetized ionosphere. Similarly, the repeated low altitude passes of Cassini through the Titan atmosphere reveal a "strongly" magnetized ionosphere. We compare the features of these two magnetized ionospheres to illustrate the differences associated with subsonic and supersonic flow.

  16. 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.

  17. Cross-section of coherent radar scattering from nonthermal plasma density fluctuations in the mid-latitude ionosphere

    NASA Astrophysics Data System (ADS)

    Kyzyurov, Yu.

    Methods based on coherent radar scattering yield very important information about nonthermal plasma density fluctuations in the lower ionosphere at different latitudes In particular the information is helpful for better understanding of the nature of the fluctuations A noticeable role in producing the fluctuations below the homopause level belongs to neutral air turbulence The turbulence is especially important in the case when development of plasma instabilities is difficult A convenient value that describes the process of radio wave coherent scattering from plasma density fluctuations is an effective cross-section sigma An analytic formula of sigma for the plasma fluctuations induced by the neutral turbulence is presented in the report The formula is obtained with the use of the 3D fluctuation spectrum predicted by a quasi-neutral fluid theory of the fluctuations Using the formula we estimated values of sigma for a possible radar backscatter experiment in the case of plasma fluctuations near the 100-km altitude in the daytime and nighttime mid-latitude ionosphere the magnetic dip angle of 45° The local values for the length-scale of the vertical plasma-density gradient L N of about 7 km and the average plasma density N e of 2 times10 10 mathrm m -3 plasma frequency f p approx 1 27 MHz were chosen for the daytime ionosphere and L N approx 3 km N e approx 2 times10 9 mathrm m -3 f p approx 0 4 MHz at night The ratio of the ion gyro-frequency to the ion-neutral collision frequency of about 0 035 and the

  18. Ionospheric climatology over Brazil: Zonal plasma velocities from experimental observations and theoretical validations

    NASA Astrophysics Data System (ADS)

    Sobral, José

    We present model calculations and experimental estimations of the zonal drift velocities over Brazil. The latter ones are derived from plasma bubbles signatures on OI6300 ? airglow images A obtained at the conjugate stations Boa Vista - BV (Geogr. 2.8N, 60.7W, dip angle: 22.0N ) and Campo Grande - CG (Geogr. 20.5S, 54.7W, dip angle: 22.32S) during the Conjugate Points Experiment COPEX carried out in Brazil between October and November 2002. Simultaneous velocities as derived by VHF and GPS techniques are also presented and compared. The theoretical ambient plasma zonal velocities were calculated using the formulations by Haerendel et al. (1992) and Eccles (1998) for which the input parameters were based on the available empirical models for zonal electric field (Scherliess and Fejer, 1999), horizontal winds (HWM- 1993), neutral constituents (MSIS-1990) and ionospheric parameters (IRI-2001). The model results show reasonable correlation coefficients between observed and predicted values. However relatively large discrepancies of magnitudes are found between them.

  19. Magnetosphere-ionosphere connection in 3D-force balanced magnetic field configurations driven by empirical plasma sheet pressure under different geomagnetic conditions

    NASA Astrophysics Data System (ADS)

    Yue, C.; Wang, C.; Zaharia, S. G.; Donovan, E.; Lyons, L. R.

    2013-12-01

    The magnetic field configuration is crucial to plasma sheet dynamics and M-I coupling. More accurate evaluation of its role requires a configuration in force balance with plasma pressure, which cannot be provided by current empirical models. In this study we established 3D force-balanced magnetic field and investigated the characteristics of field configuration and the magnetosphere-ionosphere connection for different Kp levels and solar wind dynamic pressure (PSW). We first constructed an empirical equatorial plasma pressure model using THEMIS and Geotail data, which was then used as the pressure constraint in the Zaharia [2008] magnetic field solver to obtain 3D magnetic field. The model results show that larger convection electric field during higher Kp drives plasma sheet further earthward, resulting in a substantial pressure increase near the Earth, while magnetosphere compression during higher PSW mainly enhances pressure in the tail plasma sheet. Comparing the magnetic field response to the pressure change due to increasing PSW, the Kp associated pressure increase causes the perpendicular current density (J?) peak and associated Region-2 field-aligned currents (FACs) to move deeper earthward, the magnetic field to decrease further in the near-Earth region, and field lines to stretch more significantly. The model magnetic field and its changes with Kp and PSW are found to agree fairly well with THEMIS and Geotail observations. Furthermore, we estimated the ion isotropic boundary (IB) caused by current sheet scattering for different particle energies. The IB equatorial locations match well with the earthward boundary of isotropic ions observed by THEMIS. We found that the IB is located around the transition region of dipolar to tail-like magnetic field and is close to the inner edge of Region-2 FAC. In the ionosphere, the latitudes of the IB are lower at midnight than at dawn/dusk. The IB latitudes decrease with increasing ion energy as well as with increasing Kp and PSW. These features are consistent with the IB latitudes observed by FAST satellite.

  20. 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.

  1. Ionospheric electron-content measurements during the second space-plasma negative-ion experiment (SPINEX-2)

    Microsoft Academic Search

    J. A. Fulford; J. W. MacDougall; P. A. Forsyth; M. Mendillo; P. A. Bernhardt

    1987-01-01

    The second space-plasma negative-ion experiment (SPINEX-2), a chemical-release active experiment to investigate negative-ion effects in the ionospheric F region, is described by Mendillo et al. (1982). This paper describes the electron-content measurements in somewhat more detail than would be appropriate there. The circumstances of the experiment, particularly the use of a vehicle with a very high spin rate, presented some

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  3. 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.

  4. Storm-time plasma redistribution in the coupled plasmasphere-ionosphere system: Coordinated ground and satellite observations

    NASA Astrophysics Data System (ADS)

    Chi, Peter; Tu, Jiannan; Spasojevic, Maria; Carpenter, Donald; Russell, Christopher

    The plasma distribution in the coupled plasmasphere-ionosphere system can undergo significant changes during magnetic storms, posing a challenging problem to observers and modelers for quantifying all the important physical mechanisms involved. During many magnetic storms, internal depletion occurs within the new plasmaspheric boundary layer, but the responsible physical mechanism for such depletion remains an outstanding problem. As an effort to piece together the jigsaw of this complicated phenomenon, this study examines a collection of critical ground and satellite observations, including the mass density inferred from field line resonance sounding, the charge density deduced from whistler traces, ionosonde data, and the RPI observations from the IMAGE satellite. A case study of the April 2005 storm (min Dst = -85 nT) shows that, within the new plasmaspheric boundary layer, the equatorial mass density dropped by nearly 50% after the first three days of the storm. By contrast, the equatorial charge density decreased by only 25% during the same interval. The stronger degree of heavy ion depletion coincides with a significantly lower ionospheric content at similar L-values. Our observations suggest that the concurrent negative ionospheric storm is a likely cause of the internal depletion of the storm-time plasmasphere, a scenario that can be tested by future numerical simulations of the coupled plasmasphere-ionosphere system.

  5. 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.

  6. Ionosphere. [of Jupiter

    NASA Technical Reports Server (NTRS)

    Strobel, D. F.; Atreya, S. K.

    1983-01-01

    The original interest in an ionosphere on Jupiter was generated by the discovery of strong radio-frequency emissions at approximately 20 MHz which were thought to be plasma frequencies associated with Jupiter's ionosphere. The ionosphere of Jupiter provides a means to couple the magnetosphere to the atmosphere by virtue of its high conductivity and collisional interaction with the neutral atmosphere. The Pioneer and Voyager have provided direct measurements of profiles of electron concentration at selected locations on Jupiter. Attention is given to basic principles regarding the characteristics of the Jovian ionosphere, the ionization sources, aspects of ion recombination, ion chemistry, observations of Jupiter's ionosphere, the structure of Jupiter's upper atmosphere, and questions of ionospheric modeling. On the basis of the Pioneer and Voyager observations it appears that Jupiter's ionosphere and thermosphere undergo significant solar cycle changes.

  7. Equatorial plasma bubbles in the ionosphere over Eritrea: occurrence and drift speed

    NASA Astrophysics Data System (ADS)

    Wiens, R. H.; Ledvina, B. M.; Kintner, P. M.; Afewerki, M.; Mulugheta, Z.

    2006-07-01

    An all-sky imager was installed in Asmara, Eritrea (15.4° N, 38.9° E, 7° N dip) and used to monitor the OI 630-nm nightglow. Nine months of data were studied between September 2001 and May 2002, a time including the recent maximum in the solar activity cycle. Equatorial plasma bubbles (EPBs) were recorded on 63% of nights with adequate viewing conditions. The station location within view of the equatorial ionization anomaly and with a magnetic declination near zero makes it an excellent test case for comparison with satellite studies of the seasonal variation of EPBs with longitude. The imager was accompanied by two Cornell GPS scintillation monitors, and the amplitude scintillation data are compared to the all-sky data. GPS scintillations indicate the beginning of EPBs, but die out sooner in the post-midnight period than the larger scale EPBs. Both phenomena exhibit clear occurrence maxima around the equinoxes. Ionospheric zonal drift speeds have been deduced from EPB and GPS scintillation pattern movement. Average near-midnight EPB drift speeds are between 100 and 120 m/s most months, with the GPS scintillation speeds being about the same. A winter drift speed maximum is evident in both EPB and GPS scintillation monthly means.

  8. Observations of the plasma environment during an active ionospheric ion beam

    SciTech Connect

    Pollock, C.J. (NASA Marshall Space Flight Center, Huntsville, AL (United States)); Erlandson, R.E. (Johns Hopkins Univ., Laurel, MD (United States)); Cahill, L.J. (Univ. of Minnesota, Minneapolis (United States))

    1988-10-01

    Data obtained during an active rocket-borne ion beam injection experiment (ARCS 3), which was carried out in the polar cap ionosphere over Sondre Stromfjord, Greenland, are presented and discussed. Ion flux data obtained aboard the main payload show certain characteristics which are directly attributable to known beam-injection geometry parameters, and others which are not so easily understood. Specifically, when the beam is injected transverse to the geomagnetic field, strong ion fluxes near 90{degree} magnetic pitch angle are observed, as expected. The particle energies in these cases were different from those expected, however, with separate ion flux components appearing near 100 and 15 eV/q. The expected beam energy was near 200 eV/q, so that subpayload charging to levels on the order of 100 V is inferred to have taken place during transverse beam injections. During antiparallel injections a component of {approximately}200 eV/q ions is observed to be moving up the field line, in addition to two other components: one transverse component at {approximately}200 eV/q and a sedond transverse component near 15 eV/q. In this case, no spacecraft charging is inferred. The existence of ion fluxes at magnetic pitch angle sother than those anticipated during both transverse and antiparallel beam injections indicate ion emissions from the subpayload which are much less beamlike than expected based on preflight laboratory measurements and that beam-plasma interactions tend to isotropize the beam very near the emitting payload.

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

    NASA Astrophysics Data System (ADS)

    Tu, Jiannan; Song, Paul; Vasyli?nas, Vytenis M.

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  11. Plasma impedance probe and time-correlated electron saturation current fluctuation diagnostics on the TEPCE cubesat project with application for ionospheric studies*

    NASA Astrophysics Data System (ADS)

    Cothran, C. D.; Amatucci, W. E.; Gatling, G.; Coffey, S.

    2011-12-01

    A multipoint measurement of ionospheric irregularities is possible using the Tethered Electrodynamic Propulsion Cubesat Experiment (TEPCE). This project is designed to demonstrate propulsion of a tethered satellite due to the Lorentz force acting along the current carrying tether as it crosses the Earth's magnetic field. The two cubesat end masses have plasma diagnostics to characterize the ionospheric conditions during operations. A plasma impedance probe diagnostic is designed to perform an absolute measurement of the electron density, while an electron saturation current diagnostic provides a continuous, although relative, electron density measurement. The electron saturation current measurements from the two end masses will be time correlated, thus allowing the possibility of characterizing fluctuations in the ionospheric electron density at a wave number determined by the 1km tether length and directed mostly perpendicular to the magnetic field. Such measurements could provide valuable insight into F-region instabilities (spread-F) associated with ionospheric storms. *Research supported by the Office of Naval Research

  12. Chung Park, pioneer of magnetosphere ionosphere coupling research

    NASA Astrophysics Data System (ADS)

    Carpenter, D. L.

    2007-03-01

    Chung Park (1938 2003) was a true pioneer of magnetosphere ionosphere coupling research. During a short career at Stanford University that began in 1970 and ended in 1981, he wrote seminal papers on several topics. Using ground-based whistler data, he was the first to demonstrate experimentally that day-side upward ion flow from the mid-latitude ionosphere was sufficient to maintain the night-time ionosphere. He made the only measurements to date of longitudinally localized drainage of significant quantities of plasmaspheric plasma into the underlying ionosphere during a period of enhanced convection activity. He pioneered in demonstrating the presence at ionospheric heights of geophysically important electric fields that originate in the troposphere in thunderstorm centers. He cooperated in a unique study of the guidance of whistler-mode waves by field-aligned density irregularities (ducts) in the magnetosphere. Park provided unique observational data on nonlinear wave particle interaction processes such as: (i) the development of sidebands during the injection of whistler-mode waves from Siple, Antarctica, and (ii) the mysterious whistler precursor phenomenon. Today, in spite of the several decades that have elapsed since his work, Park's early findings remain cornerstones of our understanding of magnetosphere ionosphere coupling processes. Some of his later studies of non-linear magnetospheric wave particle interaction phenomena have stirred lively debate, and today remain relevant to a number of topics in space plasma wave research.

  13. 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.

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

    NASA Technical Reports Server (NTRS)

    Wang, J.; Hastings, D. E.

    1992-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Miloch, Wojciech; Moen, Joran; Spicher, Andres

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

  16. Ionospheric modification induced by high-power HF transmitters—A potential for extended range VHF-UHF communications and plasma physics research

    Microsoft Academic Search

    W. F. Utlaut

    1975-01-01

    When the ionized upper atmosphere of the earth is illuminated by high-power HF radio waves at appropriate frequencies, the temperature of electrons in the ionosphere can be raised substantially. In addition, radio waves with sufficient energy cause parametric instabilities that generate a spectrum of intense plasma waves. Observations of these phenomena have produced new understanding of plasma processes. One consequence

  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 Tromsø with a separation of approximately 14 km. During the heating experiments GLONASS satellites are in the field of view of the receivers at high elevation angle. The links between a satellite and a receiver crossing the estimated heating area is capable of providing information about plasma irregularities along the intersection. The simultaneous measurements from the two different receivers allow detecting horizontal structures in the vicinity of the perturbed ionospheric plasmas if the distances between two piecing points are comparable to the size of heated area. The TEC variations are analyzed with regard to the relative distance between each piercing point and the heating center over a series of heating intervals. It is shown that the effects of successive changes of the heating times on the perturbed plasma density structures can be implied from the GNSS TEC signals. The results suggest that the oscillation signature of the TEC may result from the irregularities in the plasmas excited by the different HF heating intervals.

  18. Langmuir probe characteristics in a high pressure plasma in the presence of convection and ionization

    Microsoft Academic Search

    R. M. Clements; A. H. Rizvi; P. R. Smy

    1994-01-01

    The current to a Langmuir probe operating in a high pressure flowing plasma is calculated for the case where convection of electrons or ions into the sheath adjacent to the probe and thermal generation of electrons and ions within the sheath can both be significant factors in determining probe current. In addition to generating explicit relations for planar, spherical and

  19. Diversion of plasma due to high pressure in the inner magnetosphere during steady magnetospheric convection

    E-print Network

    California at Berkeley, University of

    Diversion of plasma due to high pressure in the inner magnetosphere during steady magnetospheric; revised 18 March 2012; accepted 19 March 2012; published 3 May 2012. [1] Steady magnetospheric convection (SMC) events in the Earth's magnetosphere are thought to result from balancing the rate of opening flux

  20. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  2. Generation of mesoscale convective structures in tokamak edge plasma

    SciTech Connect

    Krasheninnikov, S. I.; Smolyakov, A. I. [University of California at San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States); University of Saskatchewan, 116 Science Place, Saskatoon, Saskatchewan S7N 5E2 (Canada)

    2007-10-15

    It is shown that the interplay of the interchange drive and nonlinear effects of Reynolds stress and inverse cascade of drift wave turbulence select a range of plasma parameters (plasma pressure), for which mesoscale perturbations of a certain transverse length scale become unstable. It is suggested that the blob formation is a result of these mesoscale instabilities.

  3. 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.

  4. Convection in galaxy-cluster plasmas driven by active galactic nuclei and cosmic-ray buoyancy

    E-print Network

    Benjamin D. G. Chandran

    2004-12-20

    Turbulent heating may play an important role in galaxy-cluster plasmas, but if turbulent heating is to balance radiative cooling in a quasi-steady state, some mechanism must set the turbulent velocity to the required value. This paper explores one possible regulating mechanism associated with an active galactic nucleus at cluster center. A steady-state model for the intracluster medium is presented in which radiative cooling is balanced by a combination of turbulent heating and thermal conduction. The turbulence is generated by convection driven by the buoyancy of cosmic rays produced by a central radio source. The cosmic-ray luminosity is powered by the accretion of intracluster plasma onto a central black hole. The model makes the rather extreme assumption that the cosmic rays and thermal plasma are completely mixed. Although the intracluster medium is convectively unstable near cluster center in the model solutions, the specific entropy of the thermal plasma still increases outwards because of the cosmic-ray modification to the stability criterion. The model provides a self-consistent calculation of the turbulent velocity as a function of position, but fails to reproduce the steep central density profiles observed in clusters. The principal difficulty is that in order for the fully mixed intracluster medium to become convectively unstable, the cosmic-ray pressure must become comparable to or greater than the thermal pressure within the convective region. The large cosmic-ray pressure gradient then provides much of the support against gravity, reducing the thermal pressure gradient near cluster center and decreasing the central plasma density gradient. A more realistic AGN-feedback model of intracluster turbulence in which relativistic and thermal plasmas are only partially mixed may have greater success.

  5. A theoretical study of magnetosphere-ionosphere coupling processes

    SciTech Connect

    Cao, Fei.

    1991-01-01

    Magnetosphere and ionosphere are coupled electrodynamically by waves, field aligned currents and parallel electric fields. Several fundamental coupling processes are addressed. It is shown that the Alfven wave is the dominant mode in transmitting field aligned currents. Therefore, dynamic M-I coupling can be modeled by the Alfven wave bouncing between the ionosphere and magnetospheric boundaries. The open magnetopause, separating the solar wind and the magnetosphere, behaves like a near perfect reflector to the Alfven wave because of the large solar wind inertia. At the plasma sheet, however, the reflection coefficient may extend over a wide range, depending on the location in the plasma sheet. As the Alfven wave propagates back and forth between the magnetosphere and ionosphere, the field aligned current density increases dramatically at certain locations, especially near the head of the westward traveling surge, causing potential drops to develop along magnetic field lines. It is found that the existence of parallel potential drops can distort the global convection pattern and limit the upward field aligned current. The magnetic reconnection at the dayside magnetopause is responsible for enhancing the convection in the magnetosphere, which subsequently propagates toward the ionosphere by the Alfven wave. The patchy and intermittent reconnection at the dayside magnetopause can be initiated by the 3-D tearing instability, leading to the isolated magnetic islands and X line segments. The nonlinear evolution of tearing in terms of the magnetic island coalescence is also studied.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    Measurements from a network of digisondes and an incoherent scatter radar In Eastern North American For January 6-12, 1997 have been compared with the Field Line Interhemispheric Plasma (FLIP) model which now includes the effects of electric field convective. With the exception of Bermuda, the model reproduces the daytime electron density very well most of the time. As is typical behavior for winter solar minimum on magnetically undisturbed nights, the measurements at Millstone Hill show high electron temperatures before midnight followed by a rapid decay, which is accompanied by a pronounced density enhancement in the early morning hours. The FLIP model reproduces the nighttime density enhancement well, provided the model is constrained to follow the topside electron temperature and the flux tube is full. Similar density enhancements are seen at Goose Bay, Wallops Island and Bermuda. However, the peak height variation and auroral images indicate the density enhancements at Goose Bay are most likely due to particle precipitation. Contrary to previously published work we find that the nighttime density variation at Millstone Hill is driven by the temperature behavior and not the other way around. Thus, in both the data and model, the overall nighttime density is lowered and the enhancement does not occur if the temperature remains high all night. Our calculations show that convections of plasma from higher magnetic latitudes does not cause the observed density maximum but it may enhance the density maximum if over-full flux tubes are convected over the station. On the other had, convection of flux tubes with high temperatures and depleted densities may prevent the density maximum from occurring. Despite the success in modeling the nighttime density enhancements, there remain two unresolved problems. First, the measured density decays much faster than the modeled density near sunset at Millstone Hill and Goose Bay though not at lower latitude stations. Second, we cannot fully explain the large temperatures before midnight nor the sudden decay near midnight.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  8. An approximate solution to the continuity for ionospheric plasma in the nightside F-region

    Microsoft Academic Search

    R. G. Gachechiladze

    1985-01-01

    The continuity equation for the nightside F-region of the ionosphere is solved analytically, taking into account diffusion recombination processes. The exact expression for the ambipolar diffusion coefficient, D = D(O)e exp z\\/H, is used to calculate electron concentration profiles for a range of altitudes 270-510 km.

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

    E-print Network

    Paris-Sud XI, Université de

    scatter radar at Millstone Hill captured the ionospheric response to the ®ring of the Space Shuttle In a sequence of planned experiments, the orbital maneuvering subsystem (OMS) engines of the Space Shuttle Challenger OMS thrusters near the peak of the F layer on July 30, 1985. Details of the excitation of airglow

  10. Effects of ionospheric conductance in high-latitude phenomena

    NASA Astrophysics Data System (ADS)

    Benkevitch, Leonid

    In this thesis, the relationship between several high-latitude phenomena and the ionospheric conductance in both hemispheres is studied theoretically and experimentally. Theoretically, the high-latitude electrodynamics is studied by considering currents in the magnetosphere-ionosphere system resulting from the ionospheric sheet current redistribution between the conjugate ionospheres. It is shown that strong flow between the conjugate ionospheres, the interhemispheric currents (IHC), can be set up if the conductance distribution is asymmetric in the conjugate ionospheric regions. Such conditions are typical for solstices owing to the differences in the solar illumination. Analytical and numerical modeling shows that IHCs can appear in the regions of strong conductance gradient, more specifically around the solar terminator line, and that the intensity of the IHCs can be comparable to the intensity of the well known Region 1/Region 2 currents. The effect of IHC excitation on observable magnetic perturbations on the ground is investigated. It is shown that in the vicinity of the solar terminator line, the pattern of magnetic perturbation can be such that an apparent equivalent current vortex can be detected. In addition, strong conductance gradients are shown to affect significantly the quality of the ionospheric plasma flow estimates from the ground-based magnetometer data. Experimentally, the effect of the nightside ionospheric conductance on occurrence of substorms, global storm sudden commencement and radar auroras is investigated. To characterize substorm occurrence, new parameters, the derivatives of the classical AE and AO indices, are introduced. It is shown that the seasonal and diurnal variations of these parameters are controlled by the total nightside ionospheric conductance in the conjugate regions. The substorm onsets preferentially occur at low levels of the total conductance, which is consistent with the idea of the substorm triggering through the magnetosphere-ionosphere feedback instability. It is hypothesized that the total conductance affects the global storm onsets as well. To check this idea, the 33-year sudden storm commencement (SSC) data are considered. The semiannual, annual, semidiurnal, and diurnal variations in the SSC occurrence rate are found to be significant and these components exhibit a strong relationship with the total conductance of the high-latitude ionospheres. Finally, the SuperDARN midnight echo occurrence is shown to correlate, for some radars, with the total conductance minima and presumably with electric field maxima, which is consistent with general expectation that the F-region irregularities occur preferentially during times of enhanced electric fields. The gradients of the high-latitude conductance can also lead to significant errors in the plasma convection estimates from the ground-based magnetometers, and to investigate this effect a statistical assessment of the difference between the true plasma convection (SuperDARN) and the magnetometer-inferred equivalent convection direction is performed. The largest differences are found for the transition region between the dark and sunlit ionospheres and in the midnight sector where strong conductance gradients are expected due to particle precipitation. Consideration of regular conductance gradients due to solar illumination improves the agreement between the radar and magnetometer data. Finally, an attempt is made to demonstrate the effects of conductance upon the properties of traveling convection vortices (TCVs). Joint SuperDARN and magnetometer data reveal that there is resemblance between the magnetometer and radar inferred TCV images on a scale of thousands of kilometers. However, on a smaller scale of hundreds of kilometers, significant differences are observed.

  11. 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.

  12. Convection vortices in pre- and post-midnight sector during magnetospheric substorms

    Microsoft Academic Search

    J. Liang; G. Sofko; H. Frey

    2006-01-01

    In this study the nightside ionospheric plasma convection pattern during two substorm events is investigated from global SuperDARN observations. We find that, a postmidn ight anticlockwise convection vortex (PoACV) usually emerges at latitudes higher than the auroral brightening region after the substorm expansion phase onset. Meanwhile, an east-to-west flow reversal region wrapping around the int ensified auroras extends into the

  13. 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.

  14. On small-scale plasma inhomogeneities of the traveling ionospheric disturbances

    Microsoft Academic Search

    V. A. Alimov; F. I. Vybornov; A. V. Rakhlin

    2006-01-01

    We report on the results of the first special experiment on radio sounding of the midlatitude ionosphere by signals from in-orbit\\u000a satellites at a frequency of 150 MHz under quiet geophysical conditions. Along with the conventional correlation processing,\\u000a fractal processing of the received signals was also performed. Using the fractal approach, we obtained first data on the sources\\u000a and generation

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  17. Identification of the plasma instabilities responsible for decameter-scale ionospheric irregularities on plasmapause field lines

    NASA Astrophysics Data System (ADS)

    Eltrass, Ahmed; Ruohoniemi, J. Michael; Mahmoudian, Alireza; Scales, Wayne; De Larquier, Sebastien; Baker, Joseph; Greenwald, Ray; Erickson, Philip

    The mid-latitude SuperDARN radars have revealed decameter-scale ionospheric irregularities during quiet geomagnetic periods that have been proposed to be responsible for the observed low-velocity Sub-Auroral Ionospheric Scatter (SAIS). The mechanism responsible for the growth of such common irregularities is still unknown. Joint measurements by Millstone Hill Incoherent Scatter Radar (ISR) and SuperDARN HF radar located at Wallops Island, Virginia reported by Greenwald et al. [2006] have determined decameter-scale irregularities with low drift velocities in the quiet-time mid-latitude night-side ionosphere. Temperature gradient instability (TGI) is investigated as the cause of irregularities associated with these SuperDARN echoes. The electrostatic dispersion relation for TGI has been extended into the kinetic regime appropriate for SuperDARN radar frequencies by including Landau damping, finite gyro-radius effects, and temperature anisotropy. This dispersion relation allows study of the TGI over a wide range of parameter regimes that have not been considered for such ionospheric applications up to this time. The calculations of electron temperature and density gradients in the direction perpendicular to the geomagnetic field have shown that the TGI growth is possible in the top-side F-region for the duration of the experiment. A time series for the growth rate has been developed for mid-latitude ionospheric irregularities observed by SuperDARN in the top-side F-region [Greenwald et al., 2006]. This time series is computed for both perpendicular and meridional density and temperature gradients. These observations show the role of TGI is dominant over the gradient drift instability (GDI) in this case. Nonlinear evolution of the TGI has been studied utilizing gyro-kinetic "Particle In Cell" (PIC) simulations with Monte Carlo collisions. This allows detailed study of saturation amplitude, particle flux, heat flux, diffusion coefficient, and thermal diffusivity of the resistive drift wave turbulence. The simulation results have been compared with the linear theory. The simulations show important consequences of nonlinear evolution, particularly saturation mechanisms and wave cascading of TGI into the decameter scale regime of the radar observations. A critical comparison of computational modeling results and experimental observations is discussed

  18. Space Shuttle Exhaust Modifications of the MidLatitude Ionospheric Plasma As Diagnosed By Ground Based Radar

    Microsoft Academic Search

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

    2009-01-01

    The Space Shuttle's Orbital Maneuvering System (OMS) engines have been used since the early days of the STS program for active ionospheric modification experiments designed to be viewed by ground based ionospheric radar systems. In 1995, the Naval Research Laboratory initiated the Shuttle Ionospheric Modification with Pulsed Localized Exhaust (SIMPLEX) Program using dedicated Space Shuttle OMS burns scheduled through the

  19. Convective amplification of a three-wave parametric instability in inhomogeneous plasma

    SciTech Connect

    Zhao, Aihui; Gao, Zhe [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)] [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2013-11-15

    The three-wave parametric instability in inhomogeneous plasma is revisited and the inconsistency of the convective amplification in previous literatures is resolved. By employing multiple methods, the amplification factor of the decay mode due to the inhomogeneity is confirmed as A=??{sub 0}{sup 2}/(v{sub g1x}v{sub g2x}?{sup ?}), which is independent of the linear damping rate of the decay mode, where ?{sub 0} is the nonlinear growth rate in homogeneous plasma, v{sub g1x} and v{sub g2x} are the group velocities in the x direction of the two decay modes and ?{sup ?} is the derivative of the wavevector mismatch of the three coupled waves due to the plasma inhomogeneity.

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

    NASA Astrophysics Data System (ADS)

    Tu, J.; Song, P.

    2012-12-01

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

  1. Last studies of artificial airglow emission of ionospheric plasma at the "Sura" facility

    NASA Astrophysics Data System (ADS)

    Nasyrov, Igor; Grach, Savely; Albert, Nasyrov; Rustam, Gumerov; Vladimir, Klimenko

    Experimental results of September 2007 on artificial airglow emission at 557.7 nm [green line, the radiation of atomic oxygen level O(1 S), the excitation threshold 4.17 eV, radiation lifetime 0.7 s)] and 630 nm [red line, the radiation of atomic oxygen level O(1 D), the excitation threshold 1.96.17 eV, radiation lifetime ˜ 100 s)] during HF pumping of the ionosphere with specially designed HF pulsing sequence are reported. Ionospheric radio pumping was performed at the "Sura" radio facility situated near Nizhny Novgorod, Russia. The airglow measurements were handled by the CCD camera S1C/079FP(FU) and the newly developed mobile photometric instrument (MFI) of Kazan university (Nasyrov et al., 2007). During several "Sura" runs enhancements of the 557.7 nm airglow intensity caused by 25 ms-long pulses of pump wave were with an interpulse period 3 s were observed after the pump wave switch from continuous pumping to low duty cycle pulse radiation. The enhancements achieve the maximum (˜ +5% above the background) at ˜ 0, 6 s after the pump pulse. Then a signal intensity decreases and achieves a minimum (˜ -7% below the background) at 1.6-1.7 s after the pump pulse. In ˜ 2-2.3 s ater the pulse the airglow intensity recovers to the background level. The work is supported by RFBR (Grant No 06-02-17334). Nasyrov, I.A., Gumerov, R.I., Nasyrov, A.M., Grach, S.M.: Mobile photometric instrument for studies of ionospheric airglow emission caused by anthropogenous disturbances. VII International Suzdal URSI Symposium (ISS-07), Abstracts, p.36, 2007.

  2. Temperature structure of plasma bubbles in the low latitude ionosphere around 600 km altitude

    Microsoft Academic Search

    K.-I. Oyama; K. Schlegel; S. Watanabe

    1988-01-01

    The electron temperature inside plasma bubbles at a height of 600 km was first measured by means of Japan's seventh scientific satellite Hinotori which is an equator orbiting satellite with an inclination of 31 deg. During the period between June 1981 and February 1982, 724 plasma bubbles were detected and studied. The electron temperature inside the plasma bubbles is either

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

    SciTech Connect

    Xu, G. S. [Euratom-UKAEA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Naulin, V.; Rasmussen, J. Juul; Nielsen, A. H. [Association Euratom-Risoe DTU, DK-4000 Roskilde (Denmark); Fundamenski, W. [Euratom-UKAEA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Wan, B. N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    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.

  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. Ionospheres of the terrestrial planets

    Microsoft Academic Search

    R. W. Schunk; A. F. Nagy

    1980-01-01

    The theory and observations relating to the ionospheres of the terrestrial planets Venus, the earth and Mars are reviewed. Emphasis is placed on comparing the basic differences and similarities between the planetary ionospheres. The review covers the plasma and electric-magnetic field environments that surround the planets, the theory leading to the creation and transport of ionization in the ionspheres, the

  6. Influence of Space Plasma and Ionosphere on Interferometer Measurements at Decametre Wavelengths

    Microsoft Academic Search

    S. L. Rashkovskiy; V. A. Shepelyev

    2006-01-01

    Radio astronomical study at low frequencies and interferometer observations especially are exposed to the effect of different phenomena in the space plasma both in the source itself and along the path of radio wave propagation. The space plasma result in various effects, e.g. absorption, scattering, refraction, a delay of the radio sources radiation, and the Faraday rotation. The phenomena are

  7. Systematic study of intermediate-scale structures of equatorial plasma irregularities in the ionosphere based on CHAMP observations

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Equatorial spread-F ionospheric plasma irregularities on the night-side, commonly called equatorial plasma bubbles (EPB), include electron density variations over a wide range of spatial scales. Here we focus on intermediate-scale structures ranging from 100 m to 10 km, which play an important role in the evolution of EPBs. High-resolution CHAMP magnetic field measurements sampled along north-south track at 50 Hz are interpreted in terms of diamagnetic effect for illustrating the details of electron density variations. We provide the first comprehensive study on intermediate-scale density structures associated with EPBs, covering a whole solar cycle from 2000 to 2010. The large number of detected events, almost 9000, allows us to draw a detailed picture of the plasma fine structure. The occurrence of intermediate-scale events is strongly favoured by high solar flux. During times of F10.7 < 100 sfu practically no events were observed. The longitudinal distribution of our events with respect to season or local time agrees well with that of the EPBs, qualifying the fine structure as a common feature, but the occurrence rates are smaller by a factor of 4 during the period 2000-2005. Largest amplitude electron density variations appear at the poleward boundaries of plasma bubbles. Above the dip-equator recorded amplitudes are small and fall commonly below our resolution. Events can generally be found at local times between 19 and 24 LT, with a peak lasting from 20 to 22 LT. The signal spectrum can be approximated by a power law. Over the frequency range 1 – 25 Hz we observe spectral indices between -1.4 and -2.6 with peak occurrence rates around -1.9. There is a weak dependence observed of the spectral index on local time. Towards later hours the spectrum becomes shallower. Similarly for the latitude dependence, there is a preference of shallower spectra for latitudes poleward of the ionisation anomaly crest. Our data suggest that the generation of small plasma structure

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

    SciTech Connect

    Rose, H.; Dubois, D.; Russell, D. [Lodestar Research Corp., Boulder, CO (United States); Hanssen, A. [Univ. of Tromsoe (Norway)

    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.

  9. Incoherent scatter radar detection of enhanced plasma line in ionospheric E-region over Arecibo

    E-print Network

    Pradipta, Rezy

    2006-01-01

    A series of incoherent scatter radar (ISR) observation were conducted at the Arecibo Observatory from December 27, 2005 until January 3, 2006. From plasma line measurements that were taken during this radar campaign, we ...

  10. An investigation of methods for improving models of ionospheric plasma-density irregularities and radio-frequency scintillation

    Microsoft Academic Search

    James A. Secan; Robert M. Bussey

    1993-01-01

    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

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

    Microsoft Academic Search

    J. A. Secan; R. M. Bussey

    1993-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  13. Overlapping ionospheric and surface echoes observed by the Mars Express radar sounder near the Martian terminator

    E-print Network

    Gurnett, Donald A.

    Overlapping ionospheric and surface echoes observed by the Mars Express radar sounder near Express spacecraft occasionally show ionospheric and surface echoes that overlap in frequency ionospheric plasma frequency, respectively. In this paper we show that such overlapping echoes are only

  14. Convective growth rate of ion cyclotron waves in a H\\/+\\/He\\/+\\/ and H\\/+\\/He\\/+\\/-O\\/+\\/ plasma

    Microsoft Academic Search

    L. Gomberoff; R. Neira

    1983-01-01

    The behavior of the convective growth rate of the electromagnetic proton-cyclotron instability is investigated in detail in a H(+), He(+) plasma and when a third (minority) cold ion component such as O(+) is taken into account. It is shown that amplification is the result of an interplay between the cold species and the thermal anisotropy of the energetic protons. The

  15. 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.

  16. 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.

  17. Beryllium/Tungsten Mixed Material Analysis of FIRE Plasma Facing Components Including Convective Transport

    NASA Astrophysics Data System (ADS)

    Alman, D. A.; Ruzic, D. N.

    2003-10-01

    Extensive computer modeling for the Fusion Ignition Research Experiment (FIRE) design study focused on Be/W mixed-material erosion issues, combining several computer codes. Since the FIRE design calls for a beryllium first wall and tungsten divertor, Be can be sputtered and transported to the divertor, forming a Be/W mixture. The goal is to determine the amount of Be deposited on divertor surfaces and to model the mixture's erosion/redeposition properties. Sputtering is calculated from deuterium neutral fluxes (obtained from DEGAS2) and D^+ flux from the plasma. The ion flux includes both the diffusive flux from the UEDGE fluid code and approximations of convective (non-diffusive) transport. The sputtering of Be is determined by VFTRIM-3D. WBC+, part of Argonne's REDEP impurity transport package, calculates the transport of Be to the divertor. Results show that convective transport dominates, increasing Be sputtering to 8x10^21 s-1, with 4x10^21 s-1 reaching the divertor plates. The next step is analysis of the erosion properties of the Be/W mixed material with the ITMC code at ANL.

  18. 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.

  19. 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.

  20. In situ measurements of plasma irregularity growth in the cusp ionosphere

    NASA Astrophysics Data System (ADS)

    Oksavik, K.; Moen, J.; Lester, M.; Bekkeng, T. A.; Bekkeng, J. K.

    2012-11-01

    The Investigation of Cusp Irregularities (ICI-2) sounding rocket was launched on 5 December 2008 from Ny-Ålesund, Svalbard. The high-resolution rocket data are combined with data from an all-sky camera, the EISCAT Svalbard Radar, and the SuperDARN Hankasalmi radar. These data sets are used to characterize the spatial structure of F region irregularities in the dayside cusp region. We use the data set to test two key mechanisms for irregularity growth; the Kelvin-Helmholtz (KH) and gradient drift (GD) instabilities. Except for a promising interval of 4-6 km irregularities, the KH growth rate was found to be too slow to explain the observed plasma irregularities. The time history of the plasma gives further support that structured particle precipitation could be an important source of kilometer- to hectometer-scale “seed” irregularities, which are then efficiently broken down into decameter-scale irregularities by the GD mechanism.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  2. Nonlinear effects in the ionospheric Alfvén resonator

    Microsoft Academic Search

    D. Sydorenko; R. Rankin; K. Kabin

    2008-01-01

    A two-dimensional nonlinear multi-fluid MHD model of the ionosperic Alfvén resonator is presented. The resonator is excited by a packet of shear Alfvén waves propagating downward toward the ionosphere from high altitudes. It is shown that the nonlinear (ponderomotive) force of standing oscillations in the ionospheric Alfvén resonator creates plasma flows along the geomagnetic field that modify the plasma density

  3. 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.

  4. Observations of the plasma environment during an active ionospheric ion beam

    NASA Technical Reports Server (NTRS)

    Pollock, C. J.; Arnoldy, R. L.; Erlandson, R. E.; Cahill, L. J.

    1988-01-01

    This paper presents detailed data on positive ion flux observations acquired during an active rocket-borne ion beam injection experiment, using the hemispheric electrostatic energy and pitch angle spectrometer (HEEPS) which was separated from the beam-emitting payload by distances along and across geomagnetic field lines which varied systematically during the experiment. The data obtained by the HEEPS illustrate a number of outstanding features of the ion flux environment near the HEEPS instrument during beam operations, some of which are not understood. It is shown that particle, field, and photometric data support a picture of particularly intense beam-plasma interactions in the immediate vicinity of the beam-emitting payload.

  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. Magnetosphere-ionosphere waves

    NASA Astrophysics Data System (ADS)

    Russell, A. J. B.; Wright, A. N.

    2012-01-01

    Self-consistent electrodynamic coupling of the ionosphere and magnetosphere produces waves with clearly defined properties, described here for the first time. Large scale (ideal) disturbances to the equilibrium, for which electron inertia is unimportant, move in the direction of the electric field at a characteristic speed. This may be as fast as several hundred meters per second or approximately half the E × B drift speed. In contrast, narrow scale (strongly inertial) waves are nearly stationary and oscillate at a specific frequency. Estimates of this frequency suggest periods from several tenths of a second to several minutes may be typical. Both the advection speed and frequency of oscillation are derived for a simple model and depend on a combination of ionospheric and magnetospheric parameters. Advection of large scale waves is nonlinear: troughs in E-region number density move faster than crests and this causes waves to break on their trailing edge. Wavebreaking is a very efficient mechanism for producing narrow (inertial) scale waves in the coupled system, readily accessing scales of a few hundred meters in just a few minutes. All magnetosphere-ionosphere waves are damped by recombination in the E-region, suggesting that they are to be best observed at night and in regions of low ionospheric plasma density. Links with observations, previous numerical studies and ionospheric feedback instability are discussed, and we propose key features of experiments that would test the new theory.

  7. Nonlinearly generated plasma waves as a model for enhanced ion acoustic lines in the ionosphere

    NASA Astrophysics Data System (ADS)

    Daldorff, L. K. S.; Pécseli, H. L.; Trulsen, J.

    2007-09-01

    Observations from the EISCAT Svalbard Radar, for instance, demonstrate that the symmetry of the naturally occurring ion line can be broken by an enhanced, non-thermal, level of fluctuations, i.e., Naturally Enhanced Ion-Acoustic Lines (NEIALs). In a significant number of cases, the entire ion spectrum can be distorted, with the appearance of a third line, corresponding to a propagation velocity significantly below the ion acoustic sound speed. By numerical simulations, we consider one possible model accounting for the observations, suggesting that a primary process can be electron acoustic waves excited by a cold electron beam. Subsequently, an oscillating two-stream instability excites electron plasma waves which in turn decay to asymmetric ion lines. Our code solves the full Vlasov equation for electrons and ions, with the dynamics coupled through the electrostatic field derived from Poisson's equation.

  8. 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.

  9. Transport Induced by Large Scale Convective Structures in a Dipole-Confined Plasma B. A. Grierson,1,* M. E. Mauel,2

    E-print Network

    Mauel, Michael E.

    ], and in a dipole- confined plasma driven by strong rotation [8] or by sus- tained microwave heating [9Transport Induced by Large Scale Convective Structures in a Dipole-Confined Plasma B. A. Grierson,1,* M. E. Mauel,2 M. W. Worstell,2 and M. Klassen2 1 Princeton Plasma Physics Laboratory, Princeton

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  11. 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.

  12. A Review of Ionospheric Scintillation Models

    NASA Astrophysics Data System (ADS)

    Priyadarshi, S.

    2015-01-01

    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.

  13. 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.

  14. Dayside ionospheric conductivities at Mars

    Microsoft Academic Search

    Hermann Opgenoorth; Ranvir Dhillon; Lisa Rosenqvist; Mark Lester; Niklas Edberg; Steve Milan; Paul Withers; David Brain

    2010-01-01

    We present estimates of the day-side ionospheric conductivities at Mars based on magnetic field measurements by Mars Global Surveyor (MGS) at altitudes down to ?100km during aerobraking orbits early in the mission. At Mars, the so-called ionospheric dynamo region, where plasma\\/neutral collisions permit electric currents perpendicular to the magnetic field, lies between 100 and 250km altitude. We find that the

  15. The response of the high-latitude dayside ionosphere to an abrupt northward transition in the IMF

    NASA Astrophysics Data System (ADS)

    Ruohoniemi, J. M.; Greenwald, R. A.; de La Beaujardiere, O.; Lester, M.

    1993-07-01

    We examine the response of the high-latitude ionosphere in the prenoon sector to a northward turning of the IMF. The event was observed in the 11-13 UT interval on June 1, 1987, in the course of a multiday SUNDIAL campaign. The transition in the IMF was observed by the IMP-8 satellite which was located upstream of the earth at a distance of 36 Re. The ionospheric response in the 70-80 deg invariant latitude interval was monitored by two radars. The preexisting plasma convection observed by the radars exhibited large velocities (500-1000 m/s) and stable longterm trends, consistent with the inertial rotation of the convection pattern expected of the conditions then prevailing, B(z) less than 0, B(y) greater than 0. The plasma flow rapidly abated in response to the IMF transition. The electron density measurements made by radar in the meridional plane showed that the ionosphere had been rich in structure with the active deposition of ionization by particle precipitation. Subsequently it resembled an inactive, unstructured mid-latitude configuration. There was a dramatic decrease in the amount of backscatter observed by the HF radar. We analyze the times of transition in the various data sets and show that the ionosphere began to show the effects of the IMF transition about 2 min after its probable arrival at the magnetopause boundary.

  16. The response of the high-latitude dayside ionosphere to an abrupt northward transition in the IMF

    NASA Technical Reports Server (NTRS)

    Ruohoniemi, J. M.; Greenwald, R. A.; De La Beaujardiere, O.; Lester, M.

    1993-01-01

    We examine the response of the high-latitude ionosphere in the prenoon sector to a northward turning of the IMF. The event was observed in the 11-13 UT interval on June 1, 1987, in the course of a multiday SUNDIAL campaign. The transition in the IMF was observed by the IMP-8 satellite which was located upstream of the earth at a distance of 36 Re. The ionospheric response in the 70-80 deg invariant latitude interval was monitored by two radars. The preexisting plasma convection observed by the radars exhibited large velocities (500-1000 m/s) and stable longterm trends, consistent with the inertial rotation of the convection pattern expected of the conditions then prevailing, B(z) less than 0, B(y) greater than 0. The plasma flow rapidly abated in response to the IMF transition. The electron density measurements made by radar in the meridional plane showed that the ionosphere had been rich in structure with the active deposition of ionization by particle precipitation. Subsequently it resembled an inactive, unstructured mid-latitude configuration. There was a dramatic decrease in the amount of backscatter observed by the HF radar. We analyze the times of transition in the various data sets and show that the ionosphere began to show the effects of the IMF transition about 2 min after its probable arrival at the magnetopause boundary.

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

    SciTech Connect

    Masood, W. [TPPD, PINSTECH, P. O. Nilore, Islamabad 44000, Pakistan and National Center for Physics (NCP), Islamabad 45320 (Pakistan); Mirza, Arshad M. [Department of Physics, Theoretical Plasma Physics Group, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2010-11-15

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

  18. Convective model of a microwave discharge in a gas at atmospheric pressure in the form of a spatially localized plasma

    Microsoft Academic Search

    A. A. Skovoroda

    1997-01-01

    Experiments and a theoretical model consistent with them are presented which show that a stationary microwave discharge in\\u000a a gas at atmospheric pressure under the action of free convection due to the action of the buoyant force on the heated air\\u000a can be spatially localized, taking a spheroidal shape. Vortex motion inside the spheroid gives this localized plasma formation\\u000a some

  19. 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.

  20. 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.

  1. 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.

  2. CUTLASS Finland radar observations of the ionospheric signatures of ux transfer events and the resulting plasma ows

    E-print Network

    Paris-Sud XI, Université de

    moving away from the radar. These transients are identi®ed here as the ionospheric signature of ¯ux to the return ¯ow on closed ®eld lines. The two-beam scan oered a new and innovative opportunity to determine assumed to be a steady-state phenome- non, with the rate of creation and destruction of open ¯ux being

  3. Experimentally investigate ionospheric depletion chemicals in artificially created ionosphere

    SciTech Connect

    Liu Yu; Cao Jinxiang; Wang Jian; Zheng Zhe; Xu Liang; Du Yinchang [CAS Key Laboratory of Basic Plasma Physics, Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    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.

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

    NASA Astrophysics Data System (ADS)

    Liu, H.; Richmond, A. D.

    2013-12-01

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

  5. Plasma structuring by the gradient drift instability at high latitudes and comparison with velocity shear driven processes

    NASA Technical Reports Server (NTRS)

    Basu, Sunanda; Mackenzie, E.; Basu, S.; Coley, W. R.; Sharber, J. R.; Hoegy, W. R.

    1990-01-01

    Using results of the in situ measurements made by the DE 2 satellite, the nature of plasma structuring at high latitudes, caused by the gradient drift instability process, is described. Using noon-midnight and dawn-dusk orbits of the DE 2 satellite, it was possible to examine the simultaneous density and electric field spectra of convecting large-scale plasma density enhancements in the polar cap known as 'patches', in directions parallel and perpendicular to their antisunward convection. The results provide evidence for the existence of at least two generic classes of instabilities operating in the high-latitude ionosphere: one driven by large-scale density gradients in a homogeneous convection field with respect to the neutrals, and the other driven by the structured convection field itself in an ambient ionosphere where density fluctuations are ubiquitous.

  6. Response of ionosphere and thermosphere during radial interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Luehr, Hermann; Shue, Jihong

    2014-05-01

    The configurations of ionosphere and thermosphere have been investigated by using high-resolution measurements of CHAMP satellite. During the period IMF By and Bz components are weak and Bx keeps pointing to the Earth for almost 10 hours. The geomagnetic indices Dst is about -40 nT and AE about 100 nT on average during the interest period. The CPCP (cross polar cap potential) output by AMIE and calculated from DMSP observations have average values of 15-20 kV. Obvious hemispheric differences are shown in the configurations of FACs on the dayside and nightside. In the south pole FACs diminish in intensity with magnitudes below 0.25 µA/m2, the plasma convection retains its quiet time two cell flow pattern, and the air density is quiet low. However, there are obvious activities in the north cusp FACs. One pair of FACs emerges in the north cusp region, which shows opposite polarities to DPY FACs. The new type of currents is accompanied by sunward plasma flow channels. These ionospheric features might be manifestations of the magnetic reconnection processes occurring in the north magnetospheric flanks. The enhanced ionospheric current systems have deposited large amount of energies into the thermosphere, causing enhanced air densities in the cusp region, which subsequently propagate equatorward both on the dayside and nightside. Although the radial IMF is considered as geomagnetic quiet condition, the present study has demonstrated for the first time there are prevailing energy inputs from the magnetosphere to both the ionosphere and thermosphere in the polar cusp region.

  7. Structure of Titan's ionosphere: Model comparisons with Cassini data

    Microsoft Academic Search

    I. P. Robertson; T. E. Cravens; J. H. Waite Jr.; R. V. Yelle; V. Vuitton; A. J. Coates; J. E. Wahlund; K. Ågren; K. Mandt; B. Magee; M. S. Richard; E. Fattig

    2009-01-01

    Solar extreme ultraviolet and X-ray radiation and energetic plasma from Saturn's magnetosphere interact with the upper atmosphere producing an ionosphere at Titan. The highly coupled ionosphere and upper atmosphere system mediates the interaction between Titan and the external environment. New insights into Titan's ionosphere are being facilitated by data from several instruments onboard the Cassini Orbiter, although the Ion and

  8. Global Circulation and Temperature Structure of Thermosphere With High-Latitude Plasma Convection

    Microsoft Academic Search

    R. G. Roble; R. E. Dickinson; E. C. Ridley

    1982-01-01

    Tliis paper examines the effect of magnetospheric convection in modifying the diurnal neutral gas temperature distribution and circulation of the thermosphere for equinox conditions, using NCAR's thermospheric general circulation model. Numerical experiments are presented to illustrate the differences in temperature structure and circulation due to (1) solar heating alone, (2) solar heating plus i31asma convection with coincident geographic and geomagnetic

  9. Comparing F region ionospheric irregularity observations from C/NOFS and Jicamarca

    NASA Astrophysics Data System (ADS)

    Hysell, D. L.; Hedden, R. B.; Chau, J. L.; Galindo, F. R.; Roddy, P. A.; Pfaff, R. F.

    2009-07-01

    Observations of plasma density irregularities associated with equatorial spread F (ESF) have been made using the Jicamarca Radio Observatory and the Plasma Langmuir Probe (PLP) and Vector Electric Field Instrument (VEFI) instruments on the Communications Navigation Outage Forecast System (C/NOFS) satellite during a close spatio-temporal conjunction. The radar data resolution is of the order of 1 km and a few sec. in space and time, respectively. We find that coherent scatter intensifications at these scales are coincident and collocated with plasma density depletions as determined by C/NOFS. The Doppler shifts of the localized echoes are also comparable to the vertical components of the E × B plasma drifts. The strongest backscatter does not necessarily come from the deepest or most rapidly convecting depletions. This implies a complex relationship between coherent backscatter and the underlying state parameters in the ionospheric plasma.

  10. 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.

  11. 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.

  12. An investigation of methods for improving models of ionospheric plasma-density irregularities and radio-frequency scintillation

    NASA Astrophysics Data System (ADS)

    Secan, James A.; Bussey, Robert M.; Fremouw, Edward J.; Reinleitner, Lee A.

    1993-03-01

    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 first year, which includes construction of the modeling database, development of a new format for the internal representation of the irregularity strength, and development of new models for the diurnal, latitudinal, seasonal, and longitudinal variations in the equatorial region.

  13. An investigation of methods for improving models of ionospheric plasma-density irregularities and radio-frequency scintillation

    NASA Astrophysics Data System (ADS)

    Secan, James A.; Bussey, Robert 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 for the high latitude (auroral and polar cap) region.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    Ionospheric plasma flow is an indicator of the interconnection between the solar wind, interplanetary magnetic field (IMF), and Earth’s magnetosphere. Ionospheric convection has been mapped in the past using either a widespread data set for instantaneous convection mapping over a short time period or data from an instrument measuring convection in a spatially confined region over a long time period for the purpose of building a statistically averaged convection pattern. This study explores convection mapping using a spherical cap harmonic analysis (SCHA) technique within a localized spherical cap based on data that will be available from the Swarm three-satellite constellation. Convection is mapped in the vicinity of hypothetical Swarm satellite tracks where it is adequately constrained by data. By using statistical models to emulate Swarm measurements, we demonstrate that such mapping can be successful based on data from the Swarm A and Swarm B satellites. Convection is divided into well constrained and poorly constrained subsets to determine parameters characterizing goodness-of-fit based on known quantities. Using the subset of well constrained maps, it is determined that convection is best mapped for a spherical cap having an angular radius of ?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.

  15. The ionospheric outflow feedback loop

    NASA Astrophysics Data System (ADS)

    Moore, T. E.; Fok, M.-C.; Garcia-Sage, K.

    2014-08-01

    Following a long period of observation and investigation beginning in the early 1970s, it has been firmly established that Earth's magnetosphere is defined as much by the geogenic plasma within it as by the geomagnetic field. This plasma is not confined to the ionosphere proper, defined as the region within a few density scale heights of the F-region plasma density peak. Rather, it fills the flux tubes on which it is created, and circulates throughout the magnetosphere in a pattern driven by solar wind plasma that becomes magnetically connected to the ionosphere by reconnection through the dayside magnetopause. Under certain solar wind conditions, plasma and field energy is stored in the magnetotail rather than being smoothly recirculated back to the dayside. Its release into the downstream solar wind is produced by magnetotail disconnection of stored plasma and fields both continuously and in the form of discrete plasmoids, with associated generation of energetic Earthward-moving bursty bulk flows and injection fronts. A new generation of global circulation models is showing us that outflowing ionospheric plasmas, especially O+, load the system in a different way than the resistive F-region load of currents dissipating energy in the plasma and atmospheric neutral gas. The extended ionospheric load is reactive to the primary dissipation, forming a time-delayed feedback loop within the system. That sets up or intensifies bursty transient behaviors that would be weaker or absent if the ionosphere did not “strike back” when stimulated. Understanding this response appears to be a necessary, if not sufficient, condition for us to gain accurate predictive capability for space weather. However, full predictive understanding of outflow and incorporation into global simulations requires a clear observational and theoretical identification of the causal mechanisms of the outflows. This remains elusive and requires a dedicated mission effort.

  16. HF radar observations of temporal variations in the high latitude convection

    NASA Astrophysics Data System (ADS)

    Hanuise, C.; Villain, J. P.; Senior, C.; Cerisier, J. C.; Greenwald, R. A.; Baker, K. B.

    Coherent HF radars are presently in operation at Goose Bay and Schefferville (Canada) to study the convection in the high latitude ionosphere. From the line of sight components of the plasma velocity measured by beach radar over a common field of view nearly instantaneous maps of the two dimensional plasma flow are obtained over the auroral zone and the polar cap. These maps have a time resolution of a few minutes. They drift in MLT with the Earth rotation. From a time series of such convection maps, the variation with universal time (UT) of the latitudinal velocity profile at a fixed MLT are obtained. These represent 'true' UT time variations of the convection. Examples of such variations are shown.

  17. Comparative rocket observations of ionospheric electric fields in the auroral oval

    NASA Technical Reports Server (NTRS)

    Zanetti, L. J., Jr.; Arnoldy, R. L.; Cahill, L. J., Jr.; Behm, D. A.; Greenwald, R. A.

    1980-01-01

    The ion drift technique of measuring ionospheric electric fields is compared to two other simultaneous measurements. Rocket measurements in the evening auroral oval are checked against a dual probe, also in situ, and the ground based STARE auroral radar. The technique is explained thoroughly as well as tested for its dependence on mass. Two evening auroral oval conditions were observed from Andoya, Norway in January and February 1977. The first flight, 18:1005, measured electric fields over a quiet pre-midnight discrete arc. An interesting plasma convection reversal was observed poleward of the arc. The subsequent 18:1004, samples a breakup phase aurora nearer local midnight.

  18. Plasmapause Convects to the Magnetopause During Halloween Solar Storm

    NSDL National Science Digital Library

    Tom Bridgman

    2004-12-15

    The plasmasphere is a region of ionospheric plasma which co-rotates with the Earth, carried by the magnetic field lines. The plasmapause marks the outer boundary of this region. This colder plasma is more easily moved by the electric fields created by strong solar storms. In the Halloween 2003 event, these fields convected some of the cold plasma out to the magnetopause (grey, semi-transparent surface) and reduced the size of the cold plasma region near the Earth. For this visualization, the 3-dimensional structure was constructed from the equatorial profile of the plasmapause (as measured by IMAGE-EUV data) by extending the region along field lines of a simple dipole field.

  19. Interpreting Mars ionospheric anomalies over crustal magnetic field regions using a 2-D ionospheric model

    NASA Astrophysics Data System (ADS)

    Matta, Majd; Mendillo, Michael; Withers, Paul; Morgan, Dave

    2015-01-01

    spatially inhomogeneous, small-scale crustal magnetic fields of Mars influence the escape of planetary atmospheric species and the interaction of the solar wind with the ionosphere. Understanding the plasma response to crustal magnetic field regions can therefore provide insight to ionospheric structure and dynamics. To date, several localized spatial structures in ionospheric properties that have been observed over regions of varying magnetic field at Mars have yet to be explained. In this study, a two-dimensional ionospheric model is used to simulate the effects of field-aligned plasma transport in regions of strong crustal magnetic fields. Resulting spatial and diurnal plasma distributions are analyzed and found to agree with observations from several spacecraft and offer compelling interpretations for many of the anomalous ionospheric behaviors observed at or near regions of strong crustal magnetic fields on Mars.

  20. Effects of an atmospheric gravity wave on the midlatitude ionospheric F layer

    SciTech Connect

    Millward, G.H.; Moffett, R.J.; Quegan, S. [Univ. of Sheffield (United Kingdom); Fuller-Rowell, T.J. [Univ. of Colorado, Boulder, CO (United States)]|[Nationa Oceanic and Atmospheric Administration, Space Environment Lab., Boulder, CO (United States)

    1993-11-01

    A modeling study of the atmospheric response to a single short burst of enhanced ion convection at high latitudes, undertaken using the Sheffield/University College London/Space Environment Laboratory coupled ionosphere/thermosphere model, has revealed a large-scale atmospheric gravity wave (AGW) moving equatorward from a source in the dawn sector auroral zone. The wave propagates to midlatitude, perturbing the ionosphere and creating a traveling ionospheric disturbance. Analysis of the interaction between the thermosphere and ionosphere during the passage of the AGW at midlatitudes is undertaken and reveals a complex height-dependent response. At lower altitudes the field-aligned velocity of the ions follows closely the field-aligned wind. Above the F peak, diffusion processes become important and the field-aligned ion velocity shows fluctuations which exceded those in the wind. Changes in N{sub m}F{sub 2} and h{sub m} F{sub 2}, during the interaction, are due to redistribution of plasma alone with changes in production and loss insignificant. As the F layer is lifted by the positive surge in the gravity wave, N{sub m}F{sub 2} decreases, due to a divergence in the ion flux, itself caused by the combination of a divergent neutral wind and an increase in the effects of diffusion with altitude. The slab thickness also increases. Subsequently, the opposite happens as h{sub m}F{sub 2} falls below its equilibrium value. 14 refs., 9 figs., 1 tab.

  1. A theoretical study of the lifetime and transport of large ionospheric density structures

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    A three-dimensional time-dependent ionospheric model was used to study the spatial and temporal evolution and transport of large-scale high-density ionospheric structures for a range of solar cycle, seasonal, and IMF conditions. Both density depletions and enhancements were considered. It was found that, depending on the IMF, horizontal plasma convection can cause an initial structure to break up into multiple structures of various sizes, to become stretched into elongated segments, or to remain as a single distorted structure. The lifetime of an F-region density structure depends on several factors, including its magnitude, the initial location where it was formed, the season, the solar cycle, and the convection pattern. For example, in summer, the effects of a large density structure can disappear in a few hours or last as long as nine hours, while in winter the effects can persist for 24 hours. The passage of perturbed plasma flux tubes through sunlit and auroral regions can significantly increase the lifetime of plasma enhancements.

  2. Ionospheric imaging in Africa

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  3. Role of the atmospheric gravity waves in lithosphere-ionosphere coupling and in generation of the ionospheric earthquake precursors

    NASA Astrophysics Data System (ADS)

    Lizunov, G.; Hayakawa, M.; Hattori, K.; Mayakawa, Sh.

    Up to the present days there are no well-distinguished physical mechanisms of lithosphere-ionosphere interaction and generation of the ionospheric earthquake precursors. Several hypothetical possibilities have been suggested in the literature: (i) electric currents are generated in the lithosphere during earthquake preparation phase, the electromagnetic emission of these currents influences the ionosphere; (ii) ionosphere responds to the seismogenic variations of air conductivity and related variation of fair-weather electric field; (iii) lithosphere and ionosphere are coupled via middle-scale atmospheric gravity waves (AGW) traveling upwards to the ionospheric heights and producing the effects known as traveling ionospheric disturbances (TID). In spite of great quantity of observations of ionospheric earthquake precursors, there is a lack of appropriate experimental data: such kind of data that will help us to choose between mentioned hypotheses. Our research is devoted to the studying and verification of AGW-mechanism of seismo-ionospheric effects. The original data have been provided by synchronous measurements of atmospheric pressure variations and ionospheric plasma variations carried out in seismically active Chiba area in Japan during the year 2003. Seismogenic AGW with period about 1 hour has been selected from the broad spectra of pressure variations. Correlated ionospheric response has been detected by means of subionospheric VLF/LF propagation. Cross-analysis of barometric and ionospheric parameters has been done in order to recognize the process of AGW-coupling between perturbations at surface and ionospheric levels.

  4. 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.

  5. 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. (Carmel Research Center, Santa Monica, CA (USA))

    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.

  6. An automated analysis of DEMETER ionospheric plasma waves observations and its application to the search for anomalous emissions over the Great Sichuan EQ region

    NASA Astrophysics Data System (ADS)

    Onishi, Tatsuo; Berthelier, Jean-Jacques

    2010-05-01

    Electric field observations in the VLF range from the ICE experiment onboard the CNES DEMETER micro-satellite have been analyzed to search for anomalies possibly related to the Great Sichuan Earthquake of May 12, 2008. This work was undertaken using results from a dedicated data processing that has been recently developed at LATMOS to perform an automated recognition and characterization of the various wave emissions that are regularly detected along the orbit of DEMETER. The data processing method and the associated algorithms will be first presented and a few typical results will be shown in order to provide a detailed understanding of the algorithm capabilities. As a first full-scale application of this method, a statistical study was conducted to analyze the plasma waves observed in day-time half orbits over a region of ~1000 kilometres extent centred on the Sichuan EQ epicentre and during a period of 20 days encompassing the day of the EQ. 5 years of observations have been used to derive the statistical distribution of various types of ionospheric plasma waves that can be compared to the signals detected during the seismic active period. The first outcome of our study was the detection of a localized variation in the characteristics of the electrostatic turbulence 6 days before the EQ that appears to be unique in the whole 5 year reference observations data base. We will discuss this result and its possible interpretations.

  7. 3D multispecies MHD studies of the interaction of the ionospheres of unmagnetized solar system bodies with the solar wind or magnetospheric plasma flows

    Microsoft Academic Search

    Yifan Liu

    2000-01-01

    We used 3D multi-species MHD models to study the solar wind interaction with the ionosphere of Mars and the magnetospheric interaction with the ionospheres of Europa and Titan. Mars, Europa and Titan are all considered to be non-magnetized bodies with an atmosphere. Therefore, the global scale solar wind\\/magnetospheric interactions with these solar system bodies are with the ionosphere\\/atmosphere systems directly.

  8. 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.

  9. Direct measurements of plasma drift velocities at high magnetic latitudes.

    NASA Technical Reports Server (NTRS)

    Doupnik, J. R.; Banks, P. M.; Baron, M. J.; Rino, C. L.; Petriceks, J.

    1972-01-01

    Description of an incoherent scatter radar experiment performed at the 23-cm radar facility in Chatanika, Alaska. The experiment has provided a direct method for measuring the ionospheric plasma transport velocity vector over long periods with relatively good time resolution. Since the F-region transport at this site is closely associated with magnetospheric convection, particularly at night, the radar can provide important information about the behavior of the magnetosphere.

  10. submitted to Journal of Geophysical Research 2013JA018867 Estimating the Effects of Ionospheric Plasma on Solar-Wind/Magnetosphere

    E-print Network

    Lotko, William

    Plasma on Solar-Wind/Magnetosphere Coupling Via Mass Loading of Dayside Reconnection: Ion Laboratory Abstract: Estimates are calculated for the storm-time reduction of solar- wind/magnetosphere coupling by the mass density m of the magnetospheric plasma. Based on the application of the Cassak

  11. Large plasma density enhancements occurring in the northern polar region during the 6 April 2000 superstorm

    NASA Astrophysics Data System (ADS)

    Horvath, Ildiko; Lovell, Brian C.

    2014-06-01

    We focus on the ionospheric response of northern high-latitude region to the 6 April 2000 superstorm and aim to investigate how the storm-enhanced density (SED) plume plasma became distributed in the regions of auroral zone and polar cap plus to study the resultant ionospheric features and their development. Multi-instrument observational results combined with model-generated, two-cell convection maps permitted identifying the high-density plasma's origin and the underlying plasma transportation processes. Results show the plasma density feature of polar cap enhancement (PCE; ~600 × 103 i+/cm3) appearing for 7 h during the main phase and characterized by increases reaching up to 6 times of the quiet time values. Meanwhile, strong westward convections (~17,500 m/s) created low plasma densities in a wider region of the dusk cell. Oppositely, small (~750 m/s) but rigorous westward drifts drove the SED plume plasma through the auroral zone, wherein plasma densities doubled. As the SED plume plasma traveled along the convection streamlines and entered the polar cap, a continuous enhancement of the tongue of ionization (TOI) developed under steady convection conditions. However, convection changes caused slow convections and flow stagnations and thus segmented the TOI feature by locally depleting the plasma in the affected regions of the auroral zone and polar cap. From the strong correspondence of polar cap potential drop and subauroral polarization stream (SAPS), we conclude that the SAPS E-field strength remained strong, and under its prolonged influence, the SED plume provided a continuous supply of downward flowing high-density plasma for the development and maintenance of PCEs.

  12. A two-dimensional theory of plasma contactor clouds used in the ionosphere with an electrodynamic tether

    NASA Technical Reports Server (NTRS)

    Hastings, D. E.; Gatsonis, N. A.; Rivas, D. A.

    1988-01-01

    Plasma contactors have been proposed as a means of making good electrical contact between biased surfaces such as found at the ends of an electrodynamic tether and the space environment. A plasma contactor is a plasma source which emits a plasma cloud which facilitates the electrical connection. The physics of this plasma cloud is investigated for contactors used as electron collectors and it is shown that contactor clouds in space will consist of a spherical core possibly containing a shock wave. Outside of the core the cloud will expand anisotropically across the magnetic field leading to a turbulent cigar shape structure along the field. This outer region is itself divided into two regions by the ion response to the electric field. A two-dimensional theory of the motion of the cloud across the magnetic field is developed. The current voltage characteristic of an Argon plasma contactor cloud is estimated for several ion currents in the range of 1-100 Amperes. It is shown that small ion current contactors are more efficient than large ion current contactors. This suggests that if a plasma contactor is used on an electrodynamic tether then a miltiple tether array will be more efficient than a single tether.

  13. Assimilative mapping of ionospheric electrodynamics in the thermosphere-ionosphere general circulation model comparisons with global ionospheric and thermospheric observations during the GEM\\/SUNDIAL period of March 28-29, 1992

    Microsoft Academic Search

    B. A. Emery; G. Lu; E. P. Szuszczewicz; R. G. Roble; P. G. Richards; K. L. Miller; R. Niciejewski; D. S. Evans; F. J. Rich; W. F. Denig; D. L. Chenette; P. Wilkinson; S. Pulinets; K. F. O'Loughlin; R. Hanbaba; M. Abdu; P. Jiao; K. Igarashi; B. M. Reddy

    1996-01-01

    Satellite and ground-based observations from March 28 to 29, 1992, were combined in the assimilative mapping of ionospheric electrodynamics (AMIE) procedure to derive realistic global distributions of the auroral precipitation and ionospheric convection which were used as inputs to the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere general circulation model (TIGCM). Comparisons of neutral model winds were made with Fabry-Perot

  14. 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.

  15. The Capability of Space Mission to Study the Ionosphere and Electromagnetic Disturbances Related to Seismicn Activity

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. D.; Ruzhin, Y. Y.; Sorokin, V. M.

    2007-12-01

    Based on observational evidence, we suggest that a series of observational and modeling experiments could be carried out to demonstrate the viability of a satellite based earthquake prediction program based on a search for earthquake precursors. The satellite project has an exploratory character and aims first of all to detect the ionosphere plasma and the electromagnetic anomalies related to seismic, meteo and human activity. The observations made by the satellite have the very great advantage of very rapidly covering almost the whole of the active seismic regions in the world and monitoring the effects of a large number of earthquakes. The micro - satellite COMPASS - 2 launched on May 26, 2006. It has the capacity to carry out precise and systematic measurements around the Earth and thus to collect a maximum number of events. Without modifying the payload, like COMPASS - 2, is capable for studying the influence of storms in relation between Sun and Earth, and of assessing the impact of human activities on the ionosphere. The detailed COMPASS - 2 mission and payload description and also some results of measurements are presented. We present electrodynamic model of the atmosphere - ionosphere coupling for interpretation of satellite data. Our model gives an explanation to some electromagnetic and plasma phenomena preceding typhoons and earthquakes by amplification of DC electric field in the ionosphere over disturbed region. This field is connected with the conductivity current flowing in the atmosphere - ionosphere electric circuit, which is formed by external electric currents generated in the lower atmosphere disturbed by typhoon and earthquake preparation processes. Appearance of such currents is associated with upward transport of charged water drops and aerosols in hurricane convection zone and enhancement of charge aerosols emanation with soil gases into the atmosphere caused by growing seismic activity. The most important property of this mechanism is that numerous electromagnetic and plasma effects can be explained by the operation of only one source - an amplification of DC electric field in the ionosphere. This source is controlled by the dynamics of atmospheric processes through modification of electrical parameters of the lower atmosphere and seismic processes. The presented model could be applied to studies of the plasma and electromagnetic effects of large - scale natural and technological disasters.

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

    NASA Astrophysics Data System (ADS)

    Neubert, T.; Gilchrist, B. E.; Banks, P. M.; Sasaki, S.; Williamson, P. R.

    1991-06-01

    Plasma wave turbulence generated during electron beam injections, spacecraft potential variation, and neutral gas emissions of the Charge 2 sounding rocket experiment are reported. Charge 2 used a mother-daughter spacecraft connected by a tether. The data indicate that two processes are at work. One involves oscillations in the spacecraft potential that are picked up via the tether by the receiver aboard the daughter spacecraft. The other involves plasma noise generated by currents collected by the daughter.

  17. 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

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

    SciTech Connect

    Banerjee, Santanu, E-mail: sbanerje@ipr.res.in; Ishiguro, M.; Tashima, S.; Mishra, K. [IGSES, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Zushi, H.; Hanada, K.; Nakamura, K.; Idei, H.; Hasegawa, M.; Fujisawa, A.; Nagashima, Y.; Matsuoka, K. [RIAM, Kyushu University, Kasuga, Fukuoka 816-8580 (Japan); Nishino, N. [Mechanical System Engineering, Hiroshima University, Hiroshima 739-8527 (Japan); Liu, H. Q. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    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.

  19. VLF wave propagation and determination of ionospheric parameters

    NASA Astrophysics Data System (ADS)

    Floery, E.; Riedler, W.

    1982-06-01

    Characteristics and composition of the ionosphere were theoretically investigated by VLF wave propagation in the Earth-ionosphere waveguide. The exact mode equation is deduced and the calculation of the waveguide parameters v/c and alpha is explained. The ionospheric plasma parameters are determined by numerical simulation. Comparison of these calculations with the results of earlier VLF measurements and results from the literature shows good agreement.

  20. The morphology and physical interpretations of the longitudinal variations in the ionospheric plasma density at low-, mid- and high-latitudes

    NASA Astrophysics Data System (ADS)

    Klimenko, Maxim; Klimenko, Vladimir; Cherniak, Iurii; Zakharenkova, Irina; Ratovsky, Konstantin; Karpachev, Alexander

    As it is well known the longitudinal variations in the ionospheric electron density at equatorial, low-, mid- and high-latitudes have a number of similarities and differences. The data obtained from topside ionospheric sounding, GPS-LEO radio occultation method, worldwide network of ground-based ionosondes and GPS receivers were previously used for investigations of the various kinds of manifestations of the longitudinal ionospheric variability. We discuss and present the brief review of the recent advances and outstanding problems in this important scientific issue. We paid a special attention into our understanding of local time, seasonal, geomagnetic and solar activity dependence of the longitudinal variations in the ionospheric F region parameters. Another main objective of our report is to describe the theoretical understanding and recent model finding of the main formation mechanisms of ionospheric longitudinal variations using the Global Self-consistent Model of the Thermosphere, Ionosphere and Protonosphere (GSM TIP). We compared the GSM TIP model results with IRI empirical model, and different observation data (Intercosmos-19 satellite, DPS-4 ionosondes, GPS TEC and COSMIC ionospheric electron content). This work was supported by RFBR Grants ?14-05-00788, ?14-05-00578, and Program 22 RAS.

  1. Magnetospheric Convection The large-scale flow of rarefied plasma in the Earth's magnetosphere "is quite analogous to

    E-print Network

    Michigan, University of

    and electromagnetic waves from the magnetopause down to the ionospheres of both the northern and southern polar caps. Stern, David. A brief history of magnetospheric physics during the Space Age. Rev. Geophys., 3

  2. Cluster Plasma And Magnetic Field Measurements Of Flux Transfer Events In Conjunction With Their Ionospheric Flow Signatures

    Microsoft Academic Search

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

    2002-01-01

    We present a case study of the high-altitude northern hemispheric cusp by the Clus- ter spacecraft constellation under predominantly 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 signatures of transient reconnection for a number of hours. The ion

  3. Mapping travelling convection vortex events with respect to energetic particle boundaries

    E-print Network

    Paris-Sud XI, Université de

    : 10 March 1998 Abstract. Thirteen events of high-latitude ionospheric travelling convection vortices of the ®eld- aligned currents driving ionospheric travelling convec- tion vortices (TCV) coincide with regionsMapping travelling convection vortex events with respect to energetic particle boundaries T

  4. 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.

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

    NASA Astrophysics Data System (ADS)

    Kintner, P. M.; Lynch, K.

    2008-05-01

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

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

    SciTech Connect

    Svanda, Michal, E-mail: michal@astronomie.cz [Astronomical Institute, Academy of Sciences of the Czech Republic (v. v. i.), Fricova 298, CZ-25165 Ondrejov (Czech Republic); Astronomical Institute, Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-18000 Prague 8 (Czech Republic)

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Lühr, 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 ionosphere and thermosphere in the northern polar cusp region.

  9. REVIEWS OF TOPICAL PROBLEMS: Nonlinear effects in the ionosphere

    NASA Astrophysics Data System (ADS)

    Gurevich, A. V.

    2007-11-01

    The review is based in a report presented by the author at the RAS Physical Sciences Division's session in honor of Vitaly L Ginzburg's 90th birthday. It examines the current status of theoretical and experimental research on nonlinear phenomena arising when a powerful radio wave propagates in the ionosphere. The focus is on the modification of the ionosphere under the resonance excitation of natural plasma oscillations by radio waves. The upper-hybrid resonance gives rise to strong upper- and lower-hybrid plasma waves; excites strongly elongated ionospheric irregularities, and induces artificial ionospheric radio emission. Nonlinear processes are found to undergo complete transformation near double resonances, when the upper-hybrid frequency is close to a multiple of the electron gyromagnetic frequency. In the neighborhood of the Langmuir resonance, intense plasma waves and ion-sound waves are excited, electrons are effectively accelerated, and an artificial glow of the ionosphere appears.

  10. Theory for substorms triggered by sudden reductions in convection

    NASA Technical Reports Server (NTRS)

    Lyons, L. R.

    1996-01-01

    Many substorm expansions are triggered by interplanetary magnetic field changes that reduce magnetospheric convection. This suggests that expansion onsets are a result of a reduction in the large-scale electric field imparted to the magnetosphere from the solar wind. Such a reduction disrupts the inward motion and energization of plasma sheet particles that occur during the growth phase. It is proposed that the resulting magnetic drift of particles and a large dawn to dusk gradient in the ion energies leads to a longitudinally localized reduction in the plasma pressure, and thus, to the current wedge formation. This theory accounts for the rapid development of the expansion phase relative to growth phase, the magnitude of the wedge currents, the speeds of tailward and westward expansion of the current reduction region in the equatorial plane, and the speeds of the poleward and westward motion of active aurora in the ionosphere.

  11. Transient layers in the topside ionosphere of Mars A. J. Kopf,1

    E-print Network

    Gurnett, Donald A.

    the pulse travels at the speed of light. The maximum plasma frequency in the ionosphere, fp(max), canTransient layers in the topside ionosphere of Mars A. J. Kopf,1 D. A. Gurnett,1 D. D. Morgan,1 shown that distinct layers can occur in the topside ionosphere of Mars, well above the main photo

  12. Ionospheric modification induced by high-power HF transmitters - A potential for extended range VHF-UHF communications and plasma physics research

    Microsoft Academic Search

    W. F. Utlaut

    1975-01-01

    Radio, radar, communications, and photometric experiments are summarized which have been conducted to determine the characteristics of a volume of the ionosphere that has been intentionally modified by high-power HF radio waves. The theoretical and physical bases for ionospheric modification are outlined, high-power HF facilities are described which have been designed for experimental modification of the F-region, and diagnostic measurements

  13. LIFDAR: A Diagnostic Tool for the Ionosphere

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  14. Nonlinear interactions of electromagnetic waves with the auroral ionosphere

    Microsoft Academic Search

    Alfred Y. Wong

    1999-01-01

    The ionosphere provides us with an opportunity to perform plasma experiments in an environment with long confinement times, very large-scale lengths, and no confining walls. The auroral ionosphere with its nearly vertical magnetic field geometry is uniquely endowed with large amount of free energy from electron and ion precipitation along the magnetic field and mega-ampere current across the magnetic field.

  15. Magnetosphere sawtooth oscillations induced by ionospheric outflow.

    PubMed

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

    2011-06-01

    The sawtooth mode of convection of Earth's magnetosphere is a 2- to 4-hour planetary-scale oscillation powered by the solar wind-magnetosphere-ionosphere (SW-M-I) interaction. Using global simulations of geospace, we have shown that ionospheric O(+) outflows can generate sawtooth oscillations. As the outflowing ions fill the inner magnetosphere, their pressure distends the nightside magnetic field. When the outflow fluence exceeds a threshold, magnetic field tension cannot confine the accumulating fluid; an O(+)-rich plasmoid is ejected, and the field dipolarizes. Below the threshold, the magnetosphere undergoes quasi-steady convection. Repetition and the sawtooth period are controlled by the strength of the SW-M-I interaction, which regulates the outflow fluence. PMID:21636770

  16. 25 Years of Ionospheric Modification with the Space Shuttle

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.

    2011-12-01

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

  17. Ionospheric characteristics: a review

    SciTech Connect

    Rich, F.J.

    1983-01-01

    The ionosphere is important to spacecraft charging because the thermal ions and electrons provide a significant current to a spacecraft surface. Low, mid, and high altitude ionospheric characteristics are discussed.

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

    SciTech Connect

    Clauer, C.R.; Miller, P.M.; Sitar, R.J. [Univ. of Michigan, Ann Arbor, MI (United States)] [and others] [Univ. of Michigan, Ann Arbor, MI (United States); and others

    1995-05-01

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

  19. Joule heating of Io's ionosphere by unipolar induction currents

    NASA Technical Reports Server (NTRS)

    Herbert, F.; Lichtenstein, B. R.

    1980-01-01

    Electrical induction in Io's ionosphere, due to the corotating plasma bound to the Jovian magnetosphere, is one possible source for the attainment of the high temperatures suggested by the large scale height of Io's ionosphere. Unipolar induction models are constructed to calculate ionospheric joule heating numerically, whose heating rates lie between 10 to the -9th and 10 to the -8th W/cu m. The binding and coupling of the ionosphere is due to the dense, and possibly ionized, neutral SO2 atmosphere, and there appears to be no need to postulate the existence of an intrinsic Ionian magnetic field in order to retain the observed ionnosphere.

  20. Medium-scale traveling ionospheric disturbances observed by GPS receiver network in Japan: a short review

    Microsoft Academic Search

    Takuya Tsugawa; Nobuki Kotake; Yuichi Otsuka; Akinori Saito

    2007-01-01

    Medium-scale traveling ionospheric disturbances (MSTID) are wave-like perturbations of the ionospheric plasma with wavelengths\\u000a of several hundred kilometres and velocities of several hundred metres per second. MSTID is one of the most common ionospheric\\u000a phenomena that generally induce the perturbations of ionospheric total electron content (TEC) by ?1016 electron\\/m2, which corresponds to ?54 ns (16.2 cm) delay at GPS L1 signal. In

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

    SciTech Connect

    Ellis, I. N. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); University of California, Los Angeles, California 90095 (United States); Strozzi, D. J.; Williams, E. A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Winjum, B. J.; Tsung, F. S.; Mori, W. B.; Fahlen, J. E. [University of California, Los Angeles, California 90095 (United States); Grismayer, T. [University of California, Los Angeles, California 90095 (United States); Grupo de Lasers e Plasmas, Instituto Superior Tecnico, 1049-001 Lisboa (Portugal)

    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.

  2. Patches in the polar ionosphere: UT and seasonal dependence

    NASA Technical Reports Server (NTRS)

    Sojka, J. J.; Bowline, M. D.; Schunk, R. W.

    1994-01-01

    The seasonal and Universal Time (UT) dependencies of patches in the polar ionosphere are simulated using the Utah State University time dependent ionospheric model (TDIM). Patch formation is achieved by changing the plasma convection pattern in response to temporal changes in the interplanetary magnetic field (IMF) B(sub y) component during periods of southwrd IMF. This mechanism redirects the plasma flow from the dayside high-density region, which is the source of the tongue of ionization (TOI) density feature, through the throat and leads to patches, rather than a continuous TOI. The model predicts that the patches are absent at winter solstice (northern hemisphere) between 0800 and 1200 UT and that they have their largest seasonal intensity at winter solstice between 2000 and 2400 UT. Between winter solstice and equinox, patches are strong and present all day. Patches are present in summer as well, although their intensity is only tens of percent above the background density. These winter-to-equinox findings are also shown to be consistent with observations. The model was also used to predict times at which patch observations could be performed to determine the contributions from other patch mechanisms. This observational window is +/- 20 days about winter solstice between 0800 and 1200 UT in the northern hemisphere. In this observational window the TOI is either absent or reduced to a very low density. Hence the time dependent electric field mechanism considered in this study does not produce patches, and if they are observed, then they must be due to some other mechanism.

  3. HAARP-Induced Ionospheric Ducts

    SciTech Connect

    Milikh, Gennady; Vartanyan, Aram [University of Maryland, College Park, MD, 20742 (United States)

    2011-01-04

    It is well known that strong electron heating by a powerful HF-facility can lead to the formation of electron and ion density perturbations that stretch along the magnetic field line. Those density perturbations can serve as ducts for ELF waves, both of natural and artificial origin. This paper presents observations of the plasma density perturbations caused by the HF-heating of the ionosphere by the HAARP facility. The low orbit satellite DEMETER was used as a diagnostic tool to measure the electron and ion temperature and density along the satellite orbit overflying close to the magnetic zenith of the HF-heater. Those observations will be then checked against the theoretical model of duct formation due to HF-heating of the ionosphere. The model is based on the modified SAMI2 code, and is validated by comparison with well documented experiments.

  4. The plasma environment of Uranus

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Mcnutt, R. L., Jr.; Richardson, J. D.; Selesnick, R. S.; Sittler, E. C., Jr.; Bagenal, F.

    1991-01-01

    An overview of the observational results on the plasma environment at Uranus is given, and the implications of these observations for magnetospheric physics at Uranus are discussed. During the Voyager 2 encounter with Uranus, an extended magnetosphere filled with a tenuous plasma was detected. This low-energy plasma was found to consist of protons and electrons, with no significant heavy ion contribution, and with a density in the regions sampled by the spacecraft of at most three electrons per cubic centimeter. The plasma electrons and ions exhibit both a thermal component (with temperatures of tens of eV) and a hot component (with temperatures of a few keV). The thermal ion component is observed both inside and outside an L-shell value near 5, whereas the hot ion and electron component is excluded from the region inside of that L-shell. The source of the thermal component of the plasma is either the planetary ionosphere or the neutral hydrogen corona surrounding Uranus, whereas the hot component is convected in from the magnetotail, with probably an ionospheric source.

  5. Global Dayside Ionospheric Uplift and Enhancement Associated with Interplanetary Electric Fields

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce; Mannucci, Anthony; Iijima, Byron; Abdu, Mangalathayil Ali; Sobral, Jose Humberto A.; Gonzalez, Walter; Guarnieri, Fernando; Tsuda, Toshitaka; Saito, Akinori; Yumoto, Kiyohumi; Fejer, Bela; Fuller-Rowell, Timothy J.; Kozyra, Janet; Foster, John C.; Coster, Anthea; Vasyliunas, Vytenis M.

    2004-01-01

    The interplanetary shock/electric field event of 5-6 November 2001 is analyzed using ACE interplanetary data. The consequential ionospheric effects are studied using GPS receiver data from the CHAMP and SAC-C satellites and altimeter data from the TOPEX/ Poseidon satellite. Data from 100 ground-based GPS receivers as well as Brazilian Digisonde and Pacific sector magnetometer data are also used. The dawn-to-dusk interplanetary electric field was initially 33 mV/m just after the forward shock (IMF BZ = -48 nT) and later reached a peak value of 54 mV/m 1 hour and 40 min later (BZ = -78 nT). The electric field was 45 mV/m (BZ = -65 nT) 2 hours after the shock. This electric field generated a magnetic storm of intensity DST = -275 nT. The dayside satellite GPS receiver data plus ground-based GPS data indicate that the entire equatorial and midlatitude (up to +/-50(deg) magnetic latitude (MLAT)) dayside ionosphere was uplifted, significantly increasing the electron content (and densities) at altitudes greater than 430 km (CHAMP orbital altitude). This uplift peaked 2 1/2 hours after the shock passage. The effect of the uplift on the ionospheric total electron content (TEC) lasted for 4 to 5 hours. Our hypothesis is that the interplanetary electric field ''promptly penetrated'' to the ionosphere, and the dayside plasma was convected (by E x B) to higher altitudes. Plasma upward transport/convergence led to a 55-60% increase in equatorial ionospheric TEC to values above 430 km (at 1930 LT). This transport/convergence plus photoionization of atmospheric neutrals at lower altitudes caused a 21% TEC increase in equatorial ionospheric TEC at 1400 LT (from ground-based measurements). During the intense electric field interval, there was a sharp plasma ''shoulder'' detected at midlatitudes by the GPS receiver and altimeter satellites. This shoulder moves equatorward from -54(deg) to -37(deg) MLAT during the development of the main phase of the magnetic storm. We presume this to be an ionospheric signature of the plasmapause and its motion. The total TEC increase of this shoulder is 80%. Part of this increase may be due to a "superfountain effect." The dayside ionospheric TEC above 430 km decreased to values 45% lower than quiet day values 7 to 9 hours after the beginning of the electric field event. The total equatorial ionospheric TEC decrease was 16%. This decrease occurred both at midlatitudes and at the equator. We presume that thermospheric winds and neutral composition changes produced by the storm-time Joule heating, disturbance dynamo electric fields, and electric fields at auroral and subauroral latitudes are responsible for these decreases.

  6. Emission of whistler waves from an ionospheric tether

    E-print Network

    Takiguchi, Yu

    2009-01-01

    In this thesis, we analyze how electromagnetic waves propagate in ionosphere around the earth which is magnetized plasma. We calculate the electromagnetic wave field made by a dipole antenna at an arbitrary observation ...

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  8. Methane Group Ions Produced by Titan's Exosphere and Ionosphere

    NASA Astrophysics Data System (ADS)

    Sittler, Edward; Hartle, Richard; Simpson, David; Sarantos, Menelaos; Cooper, John; Ali, Ashraf; Lipatov, Alexander

    2014-05-01

    We will be presenting results of methane ions that can be injected into Saturn's magnetosphere as pick up ions from Titan's exosphere and outflowing methonium ions CH5+, the HCNH+ ion and the ethenium ions C2H5+ from Titan's ionosphere. Ionospheric outflows have been seen during the T9 flyby (Sittler et al., 2010), and the T63 and T75 flybys (Coates et al., 2012) where source rates to magnetosphere can be significant ~ 4.0x1024 ions/s. When methane pickup ions are born within Titan's exosphere and convective electric field points outward these ions will populate Saturn's magnetosphere, while inward convective electric field (Saturn side for dipolar magnetospheric fields) will heat the upper atmosphere and exosphere. Using 1D exosphere Westlake et al. (2011) found that the exosphere was hotter and more extended when Titan was within Saturn's sheet, while in lobe like regions of magnetosphere the exosphere is cooler. Using a 3D exosphere model, which can include winds and asymmetric heating at exobase to model methane pickup ion densities; we estimate that when within Saturn's sheet the exobase T ~ 190° K and the estimated density is ~ 2x10-3 ions/cm3 which are observable, while in lobe like regions exosphere T ~ 110° K and densities ~ 10-6 ions/cm3 not observable. The heating from methane pickup ions can be complex depending upon magnetic field geometry, dipolar (heating on Saturn side) and disc geometry (below sheet north polar heating and above sheet south polar heating). This CH4+ pickup ion density difference we estimate can be used by the CAPS ion instruments to determine if the magnetosphere is in the sheet (also plasma sheet usually dominated by water group ions with O+ ions) or lobe state (light ions H+/H2+ dominating the composition). We find CH4+ pickup ions for T36 and T39 flybs when Titan is within Saturn's magntospheric sheet, while during T41 when within lobe regions of Saturn's magnetosphere CH4+ pickup ions were not observed. But for T41 the magnetic field was equatorially confined so during approach from within Titan's wake Cassini was magnetically connected and ionospheric outflows like T9 were observed. We will discuss the compositional signatures in the CAPS IMS data and the likely chemistry of Titan's ionosphere. References: Sittler, E.C. Jr., et al., (2010), Saturn's Magnetospheric Interaction with Titan as Defined by Cassini Encounters T9 and T18: New Results, Planet. Space Sci., 58, 327-350. Coates, A.J., et al., (2012), Cassini in Titan's tail: CAPS observations of plasma escape, J. Geophys. Res., 117, A05324, doi:10.1029/2012JA017595. Westlake, J. H., et al., (2011), Titan's thermospheric response to various plasma environments, JGR, 116, A03318, doi:10.1029/2010JA016251.

  9. Long-lived plasmaspheric drainage plumes: Where does the plasma come from?

    NASA Astrophysics Data System (ADS)

    Borovsky, Joseph E.; Welling, Daniel T.; Thomsen, Michelle F.; Denton, Michael H.

    2014-08-01

    Long-lived (weeks) plasmaspheric drainage plumes are explored. The long-lived plumes occur during long-lived high-speed-stream-driven storms. Spacecraft in geosynchronous orbit see the plumes as dense plasmaspheric plasma advecting sunward toward the dayside magnetopause. The older plumes have the same densities and local time widths as younger plumes, and like younger plumes they are lumpy in density and they reside in a spatial gap in the electron plasma sheet (in sort of a drainage corridor). Magnetospheric-convection simulations indicate that drainage from a filled outer plasmasphere can only supply a plume for 1.5-2 days. The question arises for long-lived plumes (and for any plume older than about 2 days): Where is the plasma coming from? Three candidate sources appear promising: (1) substorm disruption of the nightside plasmasphere which may transport plasmaspheric plasma outward onto open drift orbits, (2) radial transport of plasmaspheric plasma in velocity-shear-driven instabilities near the duskside plasmapause, and (3) an anomalously high upflux of cold ionospheric protons from the tongue of ionization in the dayside ionosphere, which may directly supply ionospheric plasma into the plume. In the first two cases the plume is drainage of plasma from the magnetosphere; in the third case it is not. Where the plasma in long-lived plumes is coming from is a quandary: to fix this dilemma, further work and probably full-scale simulations are needed.

  10. 3D Multispecies Hybrid Simulations of Titan's Highly Variable Plasma Environment

    NASA Astrophysics Data System (ADS)

    Simon, S.; Boesswetter, A.; Bagdonat, T.; Motschmann, U.

    2006-12-01

    We present three-dimensional hybrid simulations of the interaction between Titan's ionosphere and the Saturnian magnetospheric plasma flow. Titan's orbit is located inside Saturn's magnetosphere most of the time, where the corotating plasma flow is superalfvenic, yet subsonic and submagnetosonic. Due to the characteristic length scales of the interaction region being comparable to the ion gyroradii in the vicinity of Titan, magnetohydrodynamic models can only offer a rough description of Titan's plasma environment. For this reason, Titan's plasma interaction has been studied by using a three-dimensional hybrid simulation code, treating the electrons as a massless, charge-neutralizing fluid, whereas a completely kinetic approach is used to cover ion dynamics. The simulations include up to two magnetospheric and three ionospheric ion species. The calculations are performed on a curvilinear simulation grid which can be adapted to the spherical geometry of the obstacle. In the model, Titan's dayside ionosphere is mainly generated by solar UV radiation. Since the Titan interaction features the possibility of having the densest ionosphere located on a face not aligned with the ram flow of the magnetospheric plasma, a variety of different scenarios can be studied. The simulations show the formation of a strong magnetic draping pattern and an extended pick-up region, being highly asymmetric with respect to the direction of the convective electric field. Besides, the results indicate that Titan's ionospheric tail acts like a natural mass-spectrometer. Due to the dependence of the gyroradii on the ion mass, ions of different masses become spatially dispersed in the tail region. The simulations also illustrate that the pick-up process of the light ionospheric species is slowed down by the heavier ones. The results are in agreement with data from recent Cassini flybys.

  11. Incoherent scatter from space shuttle and rocket engine plumes in the ionosphere

    NASA Astrophysics Data System (ADS)

    Bernhardt, P. A.; Huba, J. D.; Swartz, W. E.; Kelley, M. C.

    1998-02-01

    Enhanced echoes from the 430 MHz radar at Arecibo were observed during burns of the space shuttle orbital maneuver subsystem (OMS) engines near 317 km altitude. Similar radar signatures of enhanced backscatter were also obtained by the Millstone Hill radar observing the plume of a Centaur engine burning in the ionosphere. A theoretical model of incoherent scatter is presented to explain the radar backscatter observations. The theory considers molecular ion beams generated in the exhaust plume as a result of charge exchange between the ambient O+ ions and the high-speed exhaust molecules (primarily H2O). The field-aligned gyromotion of the pickup ions affects the radio wave scattering from the random thermal fluctuations of electron density. Numerical calculations are carried out for plasmas modified by the space shuttle or Centaur engines, and reasonable agreement with observations is found for the total scattered power. Incoherent backscatter spectra respond to characteristics of the exhaust plume such as vector flow velocity, temperature, and composition. The nonequilibrium velocity distributions for the ions in the pickup ion plume are similar to the distributions found in strongly convecting auroral region ionospheres. The incoherent scatter from the plume ions can be used to validate techniques used to study naturally disturbed plasmas. The predictions of our radar scatter calculations will be tested in future experiments using the space shuttle OMS engines over incoherent scatter radars located at equatorial latitudes and midlatitudes.

  12. Ionospheric phenomena before strong earthquakes

    Microsoft Academic Search

    A. S. Silina; E. V. Liperovskaya; V. A. Liperovsky; C.-V. Meister

    2001-01-01

    A statistical analysis of several ionospheric parameters before earthquakes with magnitude M > 5.5 located less than 500 km from an ionospheric vertical sounding station is performed. Ionospheric effects preceding \\

  13. An assessment of the relative importance of body and plasma properties in determining the ion current distribution in the wake of an ionospheric satellite

    Microsoft Academic Search

    U. Samir; Y. J. Kaufman

    1980-01-01

    The degree and range of applicability of some simple wake models are discussed in the study of satellite-ionosphere interactions, utilizing experimental results. The theoretical models used are based on a quasi-neutral approximation for oxygen ions and a neutral approximation for hydrogen ions.

  14. Kinetic Framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System: A UnifiedApproach for Studying Hot and Cold Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Karimabadi, H.; Omelchenko, Y.; Schunk, R. W.; Barakat, A. R.; Gardner, L. C.; Khazanov, G. V.; Glocer, A.; Kistler, L. M.

    2013-12-01

    The Magnetosphere-Ionosphere-Plasmasphere-Polar Wind System is complex; it varies on a wide range in spatial and temporal scales, exhibits relatively thin ion-scale boundaries (e.g., bow shock, magnetopause, magnetotail), contains hot and cold particle populations, and the particle distribution functions are typically non-Maxwellian. The existing space weather frameworks are based on global fluid models and therefore cannot address many important issues concerning particle, momentum, and energy coupling in the system. To remedy this situation, we have formed a multi-disciplinary team to create a new kinetic modeling framework. The new framework will include kinetic electron and ion formulations for the ionosphere, plasmasphere, and polar wind domains, and kinetic ions and fluid electrons for the magnetosphere. The proposed methodology is expected to lead to breakthroughs in studying numerous problems/issues, including the self-consistent formation of the ring current, the self-consistent formation of ion scale turbulence and waves, the calculation of appropriate reconnection rates, the effect that multiple species and ion outflows from the ionosphere have on the development and evolution of storms/substorms, among others. The presentation will focus on the current state and capabilities of the global kinetic models that form the framework for the Magnetosphere-Ionosphere-Plasmasphere-Polar Wind Model.

  15. Two-dimensional electric field measurements in the ionospheric footprint of a flux transfer event

    NASA Astrophysics Data System (ADS)

    McWilliams, K. A.; Yeoman, T. K.; Cowley, S. W. H.

    2000-12-01

    Line-of-sight Doppler velocities from the SuperDARN CUTLASS HF radar pair have been combined to produce the first two-dimensional vector measurements of the convection pattern throughout the ionospheric footprint of a flux transfer event (a pulsed ionospheric flow, or PIF). Very stable and moderate interplanetary magnetic field conditions, along with a preceding prolonged period of northward interplanetary magnetic field, allow a detailed study of the spatial and the temporal evolution of the ionospheric response to magnetic reconnection. The flux tube footprint is tracked for half an hour across six hours of local time in the auroral zone, from magnetic local noon to dusk. The motion of the footprint of the newly reconnected flux tube is compared with the ionospheric convection velocity. Two primary intervals in the PIF's evolution have been determined. For the first half of its lifetime in the radar field of view the phase speed of the PIF is highly variable and the mean speed is nearly twice the ionospheric convection speed. For the final half of its lifetime the phase velocity becomes much less variable and slows down to the ionospheric convection velocity. The evolution of the flux tube in the magnetosphere has been studied using magnetic field, magnetopause and magnetosheath models. The data are consistent with an interval of azimuthally propagating magnetopause reconnection, in a manner consonant with a peeling of magnetic flux from the magnetopause, followed by an interval of anti-sunward convection of reconnected flux tubes.

  16. Multi-instrument observations of plasma features in the Arctic ionosphere during the main phase of a geomagnetic storm in December 2006

    NASA Astrophysics Data System (ADS)

    Wu, Ye-wen; Liu, Rui-yuan; Zhang, Bei-chen; Wu, Zhen-sen; Hu, Hong-qiao; Zhang, Shun-rong; Zhang, Qing-he; Liu, Jun-ming; Honary, F.

    2013-12-01

    Arctic ionospheric variations during the main phase of a magnetic storm on 14-15 December, 2006 were investigated to characterize the high energy particle precipitation caused effects, based on multi-instrument observations. These include electron density observations provided by the Global Positioning System (GPS) total electron content (TEC) measurements, European Incoherent Scatter (EISCAT) radar, the radio occultation (RO) from both the CHAMP satellite and the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite, as well as the ionospheric absorption of cosmic radio noise measured by the Imaging Riometer for Ionospheric Studies (IRIS) at Kilpisjärvi in the northern Finland (69.05°N, 20.79°E). Significant increases in the electron density for these different observations were found in the Arctic ionosphere during the main phase of the magnetic storm. These increase occurred in Scandinavian, Northwest part of Russia and Svalbard (SNRS) region, primarily at an altitude of about 110 km. These results are first reported for the SNRS region, and our study contributes to a more complete description of this space weather event during 14-15 December, 2006. Our observations also provide direct evidence that the stormtime E-layer electron density enhancement (e.g., the sporadic E) can form a nearly dominant portion in the observed TEC increase. These increases were accompanied by the ionospheric absorption enhancement at the altitude of about 90 km. The Y-component of magnetic field to the south of SNRS decreased, indicating strong upward field aligned electric current in the Arctic ionosphere. These features are interpreted as the effect of the high energy electron precipitation during the magnetic storm, which is caused by the sub-storm reflected on AL index and the measurements of IMAGE (International Monitor for Auroral Geomagnetic Effects) chain. The average energy of the precipitation electrons reached to about 10 keV and the boundary of the high energy electron precipitation was also found to move poleward with a speed of about 800 m/s.

  17. Magnetosphere-Ionosphere Coupling Processes in the Ionospheric Trough Region During Substorms

    NASA Astrophysics Data System (ADS)

    Zou, S.; Moldwin, M.; Nicolls, M. J.; Ridley, A. J.; Coster, A. J.; Yizengaw, E.; Lyons, L. R.; Donovan, E.

    2013-12-01

    The ionospheric troughs are regions of remarkable electron density depression at the subauroral and auroral latitudes, and are categorized into the mid-latitude trough or high-latitude trough, depending on their relative location to the auroral oval. Substorms are one fundamental element of geomagnetic activity, during which structured field-aligned currents (FACs) and convection flows develop in the subauroral and auroral ionosphere. The auroral/trough region is expected to experience severe electron density variations during substorms. Accurate specification of the trough dynamics during substorms and understanding its relationship with the structured FACs and convection flows are of important practical purpose, including providing observational foundations for assessing the attendant impact on navigation and communication. In addition, troughs are important since they map to magnetospheric boundaries allowing the remote sensing of magnetosphere-ionosphere coupling processes. In this talk, we discuss the dynamics of the mid-latitude and high-latitude troughs during substorms based on multi-instrument observations. Using GPS total electron content (TEC) data, we characterize the location and width of the mid-latitude trough through the substorm lifecycle and compare them with existing trough empirical models. Using a combination of incoherent scattering radar (ISR), GPS TEC, auroral imager and a data assimilative model, we investigate the relationship between the high-latitude trough and FACs as well as convection flows. The high-latitude trough is found to be collocated with a counter-clockwise convection flow vortex east of the Harang reversal region, and downward FACs as part of the substorm current system are suggested to be responsible for the high-latitude trough formation. In addition, complex ionospheric electron temperature within the high-latitude trough is found, i.e., increase in the E region while decrease in the F region. We discuss possible processes responsible for this complex temperature change, such as ion composition change and/or presence of downward FACs.

  18. Uplift of Ionospheric Oxygen Ions During Extreme Magnetic Storms

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Mannucci, Anthony J.; Verkhoglyadova, Olga P.; Huba, Joseph; Lakhina, Gurbax S.

    2013-01-01

    Research reported earlier in literature was conducted relating to estimation of the ionospheric electrical field, which may have occurred during the September 1859 Carrington geomagnetic storm event, with regard to modern-day consequences. In this research, the NRL SAMI2 ionospheric code has been modified and applied the estimated electric field to the dayside ionosphere. The modeling was done at 15-minute time increments to track the general ionospheric changes. Although it has been known that magnetospheric electric fields get down into the ionosphere, it has been only in the last ten years that scientists have discovered that intense magnetic storm electric fields do also. On the dayside, these dawn-to-dusk directed electric fields lift the plasma (electrons and ions) up to higher altitudes and latitudes. As plasma is removed from lower altitudes, solar UV creates new plasma, so the total plasma in the ionosphere is increased several-fold. Thus, this complex process creates super-dense plasmas at high altitudes (from 700 to 1,000 km and higher).

  19. LISN: A distributed observatory to image and study ionospheric irregularities

    NASA Astrophysics Data System (ADS)

    Sheehan, R.; Valladares, C. E.

    2013-05-01

    During nighttime the low-latitude ionosphere commonly develops plasma irregularities and density structures able to disrupt radio wave signals. This interference produces an adverse impact on satellite communication and navigation signals. For example, EM signals originated from satellites can suffer fading as deep as 20 dB even at UHF frequencies. In addition, civil aviation is increasingly dependent upon Global Navigation Satellite Systems and disruption of the navigation capability from ionospheric irregularities poses a clear threat to passengers and crews. To monitor and specify the conditions of the ionosphere over South America, the Low-latitude Ionospheric Sensor Network (LISN) was established as a permanent array of scientific instruments that operate continuously and transmit their observables to a central server in a real-time basis. Presently, the LISN observatory includes 3 different types of instruments: (1) 47 GPS receivers, (2) 5 flux-gate magnetometers and (3) 2 Vertical Incidence Pulsed Ionospheric Radar (VIPIR) ionosondes. In addition to providing a nowcast of the disturbed state of the ionosphere over South America, LISN permits detailed studies of the initiation and development of plasma irregularities. By using data assimilation and tomography techniques, LISN provides continuous estimates of several important geophysical parameters that are indispensable to a program aimed at forecasting the plasma electrodynamics and the formation of density structures in the low-latitude ionosphere.

  20. Saturn: atmosphere, ionosphere, and magnetosphere.

    PubMed

    Gombosi, Tamas I; Ingersoll, Andrew P

    2010-03-19

    The Cassini spacecraft has been in orbit around Saturn since 30 June 2004, yielding a wealth of data about the Saturn system. This review focuses on the atmosphere and magnetosphere and briefly outlines the state of our knowledge after the Cassini prime mission. The mission has addressed a host of fundamental questions: What processes control the physics, chemistry, and dynamics of the atmosphere? Where does the magnetospheric plasma come from? What are the physical processes coupling the ionosphere and magnetosphere? And, what are the rotation rates of Saturn's atmosphere and magnetosphere? PMID:20299587

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

    Microsoft Academic Search

    G. Lu; A.D. Richmond; B. A. Emery; R. G. Roble

    1995-01-01

    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

  2. Dayside convection and auroral morphology during an interval of northward interplanetary magnetic eld

    E-print Network

    Boyer, Edmond

    Dayside convection and auroral morphology during an interval of northward interplanetary magnetic and ionospheric convection during an interval when the interplanetary magnetic ®eld (IMF) had predominantly radar. For an interval of IMF By 0 nT, these convection ¯ow measurements suggest the presence

  3. Infrasound in the ionosphere and disturbances triggered by earthquakes

    NASA Astrophysics Data System (ADS)

    Chum, Jaroslav; Hruška, František; Laštovi?ka, Jan; Šindelá?ová, Tereza; Zedník, Jan

    2013-04-01

    We report an overview of observation of infrasound waves in the ionosphere over the Czech Republic by multi-point Continuous Doppler sounding system. We conclude that these observations are rare. The infrasound waves of periods about 3 minutes (~2.5 to ~4.5 minutes) were observed in the case of passages of extreme convective systems or cold fronts. Unusually strong infrasound waves (large Doppler shift frequencies) with mean periods about 50 s were observed about 9 minutes after the arrival of seismic waves excited by the 11 March 2011 Tohoku earthquake (M~9). This time delay is consistent with vertical propagation of infrasound from the ground below (not from epicenter) to the height of observation (210-220 km). For several wave packets, the fluctuations of Doppler shift frequencies showed very good (0.98) cross-correlation with the vertical velocity of the ground surface motion. The individual wave packets recorded on the ground had different observed horizontal velocities and corresponded to different types of seismic waves. A comparison of the vertical velocities of ground motion with oscillation velocities of air particles in the ionosphere (derived from Doppler shift measurements) indicates that about 1/10 of the infrasound energy flux excited at the ground reached the altitudes of ~210-220 km for wave periods longer than ~30 s. A similar phenomenon was also observed for the 17 February 2010 earthquake near Chile coast. It is also shown that to get reasonable oscillation velocities of air particles from the observed Doppler shift frequencies a simple mirror-like approximation of reflection of sounding radio waves (radar formula) cannot be used. It is necessary to consider the value of electron density gradient at the reflection height, and air (plasma) compression owing to the infrasound wave.

  4. Wenchuan Earthquake Ionospheric Precursors: Modeling and Experiment

    NASA Astrophysics Data System (ADS)

    Klimenko, Maxim; Klimenko, Vladimir; Zhao, Biqiang; Pulinets, Sergej; Zakharenkova, Irina; Bryukhanov, Valerij

    Early it was shown, that for strong middle-latitude earthquakes the effects in Total Electron Content (TEC) and in critical frequency of F2-layer (foF2) look like local changes in electron concentration which maxima are located in immediate proximity from epicenter area. Pre-cursory effects of strong near-equatorial earthquakes might be in the form of deepening and widening of electron concentration minimum over the magnetic equator and displacement of equatorial ionization anomaly crests. The problems of physical explanation of possible forma-tion mechanisms of the seismo-ionospheric effects are under discussion now. In Namgaladze et al., 2009 it has been come out with the assumption, that the most probable formation mech-anism of TEC disturbed areas, observable prior strong earthquakes, is the vertical transport of the F2-region ionospheric plasma under the zonal electric field action. The geomagnetic conjugacy of the earthquake ionospheric precursors and effects in equatorial anomaly which development is controlled by zonal electric field are strong arguments in favor of this hypoth-esis. Besides, the analysis of model calculation results with use of the Global Self-consistent Model of the Thermosphere, Ionosphere, Protonosphere (GSM TIP) in Namgaladze et al., 2009 testifies in favor of this hypothesis. There is a question how such electric fields can arise in the ionosphere prior to earthquakes? Now it is not answer to this question. Therefore, for understanding of formation mechanisms of earthquake ionospheric precursors it is necessary to understand the physics of lithosphere-atmosphere-ionosphere coupling prior to earthquake. Many researchers tried to solve this problem. However, until now there is not common opinion concerning to the lithosphere-atmosphere-ionosphere coupling prior to earthquake. Some ba-sic hypotheses for the explanation of this mechanism have been offered: the Internal Gravity Waves (IGWs) of seismogenic origin with the period 1-3 hours, the IGWs with the period from several minutes up to tens minutes, the seismogenic electric field with amplitude from units up to tens mV/m, the abnormal electromagnetic fields and emissions. However, the appearance of local large-scale seismo-ionospheric anomalies in TEC and foF2 it is possible to explain only by two of the mentioned mechanisms: an atmospheric electric field and/or small-scale IGWs. In this study, we present the numerical calculation results for reproduction of observed changes in the ionosphere prior to strong Wenchuan earthquake. This earthquake has been fixed on 12 May 2008. The geomagnetic activity indices for the period on 1-13 May were low. The calcu-lations of Wenchuan earthquake ionospheric precursors were carried out with use of the GSM TIP model. In calculations, the small-scale IGWs and/or the penetration of vertical electric field are considered as the formation mechanisms of earthquake ionospheric precursors. It was carried out the comparison of calculation results with experimental data of TEC and foF2 at various stations, located in China and nearby areas. The obtained results confirm the proposed mechanisms of seismo-ionospheric effect formation by small-scale IGWs and the penetration of the seismogenic vertical electric field from the atmosphere into the ionosphere. References Namgaladze A.A., Klimenko M.V., Klimenko V.V. and Zakharenkova I.E. Physical Mechanism and Mathematical Simulation of Ionosphere Earthquake Precursors Observed in Total Electron Content. Geomagnetism and Aeronomy, 2009, Vol. 49, 252-262.

  5. Novel Modeling of Mars' Ionospheric Electrodynamics

    NASA Astrophysics Data System (ADS)

    Riousset, J. A.; Paty, C. S.; Lillis, R. J.; Fillingim, M. O.; England, S.; Withers, P.

    2011-12-01

    The complex interaction between Mars' unique crustal magnetic fields and upper atmospheric electrons, ions and neutrals leads to the formation of currents in the ionospheric dynamo region (i.e., where electrons are magnetized but ions are collisional). These interactions involve elastic and inelastic collisions between ions, electrons and neutrals in the presence of varying bulk motion, pressures, temperatures and densities. In addition, the inherent inhomogeneities in the crustal field causes open and closed magnetic field regions to be in very close proximity. The resulting 'patchy' ionosphere varies on spatial scales of ? ˜100 km. These conditions make it impossible to derive an analytical solution of these ionospheric currents. Here we present the methodology, validation and preliminary results of a novel model of Mars' ionospheric currents. The model performs three-dimensional, multi-fluid, self-consistent simulations of electrodynamics in the region of Mars' ionosphere (˜75-400 km altitude), where differential motion between ions and electrons occurs. Our work is built upon a multi-fluid plasma dynamic model that tracks three ions species (O2+, CO2+, and O+) and electrons. This method applies equations for conservation of mass, conservation of momentum, charge neutrality, and time-dependent pressure for ion species and electrons while simultaneously solving the generalized Ohm's Law and Maxwell-Ampere equation for the electric and magnetic fields. Incorporated into these equations are the aforementioned collisional interactions between the ions, electrons and neutrals. Our results demonstrate the feasibility of a self-consistent model of Mars' ionospheric electrodynamics, and focus on a thorough and methodic validation of each aspect of the model. Our goal is to build a solid ground for the study of the effects of thermospheric neutral winds, magnetic topologies, and day-night variations on the formation and evolution of ionospheric currents on Mars.

  6. Ionospheric correction of space radar data

    NASA Astrophysics Data System (ADS)

    Hapgood, Mike

    2010-06-01

    Radar is a critical tool for maintaining knowledge of the many objects in low Earth orbit and thus for maintaining confidence that societies around the world are secure against a variety of space-based threats. It is therefore important to raise awareness that LEO objects are embedded in the envelope of relatively dense plasma that co-rotates with the Earth (ionosphere-plasmasphere system) and thus accurate tracking must correct for the group delay and refraction caused by that system. This paper seeks to promote that awareness by reviewing those effects and high-lighting key issues: the need to customise correction to the altitude of the tracked object and prevailing space weather conditions, that ionospheric correction may be particularly important as an object approaches reentry. The paper outlines research approaches that should lead to better techniques for ionospheric correction and shows how these might be pursued in the context of the EURIPOS initiative.

  7. Effects of the active auroral ionosphere on magnetosphere - ionosphere coupling

    Microsoft Academic Search

    Dimitri Pokhotelov

    2003-01-01

    The thesis is devoted to the effects of electromagnetic coupling between the Earth's magnetosphere and the active auroral ionosphere. The research has been focused, in particular, on the concept of ionospheric feedback instability. The feedback instability arises when localized perturbations in ionospheric conductivity become polarized in the presence of background electric field. Under favorable conditions of low ionospheric conductivity and

  8. Solar wind interaction with the ionosphere of Venus inferred from radio scintillation measurements

    SciTech Connect

    Woo, R.; Sjogren, W.L.; Kliore, A.J. (California Institute of Technology, Pasadena (USA)); Luhmann, J.G. (Univ. of California, Los Angeles (USA)); Brace, L.H. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

    1989-02-01

    This paper presents the first S-band (2.3 GHz) radio scintillations observed in the ionosphere of Venus and discovered when the Pioneer Venus Orbiter spacecraft traversed the ionosphere of Venus. In situ plasma measurements as well as propagation calculations confirm that the scintillations are caused by electron density irregularities in the topside ionosphere of Venus below the ionopause. While these topside plasma irregularities have not been studied before, simultaneous magnetic field measurements presented here reveal that they are associated with the penetration of large-scale magnetic fields in the ionosphere. Previous studies based on extensive magnetic field measurements have shown that the presence of large-scale magnetic fields occurs in the subsolar region when the solar wind dynamic pressure exceeds the ionospheric plasma pressure. As with the large-scale magnetic fields, the disturbed plasma and resulting scintillations are therefore a manifestation of high-dynamic solar wind interaction with the ionosphere. Since the scintillations only occur in the subsolar region of Venus, the global morphology of ionospheric scintillations at Venus is different from that of the terrestrial ionosphere, where scintillations are observed in both polar and equatorial regions, with peaks occurring during nighttime. This difference apparently stems from the fact that Venus is not a magnetic planet. The authors also demonstrate that the disturbed plasma produced by the high-dynamic solar wind interaction can be remotely sensed by scintillations during radio occultation measurements, that is, when the spacecraft is outside the ionosphere.

  9. USU (Utah State University) Center of Excellence in theory and analysis of the geo-plasma environment. Final technical report

    SciTech Connect

    Schunk, R.W.

    1989-11-30

    A team of eleven Ph.D. scientists and several graduate students was assembled at USU to work in close collaboration with scientists at the Air Force Geophysics Lab on a number of problems that are relevant to Air Force systems, including OTH radars, communications, and orbiting space structures. The overall goal of the research was to obtain a better understanding of the basic chemical and physical processes operating in the geoplasma environment, including the ionosphere, thermosphere, and magnetosphere. Some of the specific tasks included the following: (1) Studies of ionospheric structure and irregularities; (2) Study the feasibility of developing better operational ionospheric models for the Air Force; (3) Conduct model/data comparisons in order to validate the ionospheric models; (4) Study plasma convection characteristics in the high-latitude ionosphere; (5) Study magnetosphere-ionosphere coupling problems; (6) Construct a thermospheric general circulation model; (7) Develop a 3D, time-dependent model of the outer plasmasphere; (8) Develop a 3D, time-dependent MHD model of the earth's magnetosphere; (9) Conduct satellite drag studies; and (10) Study certain spacecraft-environment interaction problems, including those related to high-voltage power sources, spacecraft outgassing, and spacecraft charging at LEO altitudes.

  10. International reference ionosphere 1990

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter; Rawer, K.; Bossy, L.; Kutiev, I.; Oyama, K.-I.; Leitinger, R.; Kazimirovsky, E.

    1990-01-01

    The International Reference Ionosphere 1990 (IRI-90) is described. IRI described monthly averages of the electron density, electron temperature, ion temperature, and ion composition in the altitude range from 50 to 1000 km for magnetically quiet conditions in the non-auroral ionosphere. The most important improvements and new developments are summarized.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  12. Survey and prediction of the ionospheric scintillation using data mining techniques

    NASA Astrophysics Data System (ADS)

    Rezende, L. F. C.; de Paula, E. R.; Stephany, S.; Kantor, I. J.; Muella, M. T. A. H.; de Siqueira, P. M.; Correa, K. S.

    2010-06-01

    Irregularly structured ionospheric regions may cause amplitude and phase fluctuations of radio signals. Such distortion is called ionospheric scintillation. These ionospheric irregularities occur as part of depleted plasma density regions that are generated at the magnetic equator after sunset by equatorial ionospheric plasma instability mechanism. Also known as ionospheric bubbles, they drift upward to high altitudes at the equator and extend/expand to low latitudes along the Earth magnetic field lines. Ionospheric irregularities affect the space weather since they present large variations with the solar cycle and during solar flares and coronal mass ejections. In general, navigation systems such as the Global Positioning System and telecommunications systems are also affected by the scintillation. The aim of this work is to apply data mining for the prediction of ionospheric scintillation. Data mining can be divided into two categories: descriptive or predictive. The first one describes a data set in a concise and summarized way, while the second one, used in this work, analyzes the data to build a model and tries to predict the behavior of a new data set. In this study we employed data series of ionospheric scintillation and other parameters such as the level of solar activity, vertical drift velocity of the plasma at the magnetic equator, and magnetic activity. The results show that prediction of the ionospheric scintillation occurrence during the analyzed period was possible regardless of the high variability of the ionospheric parameters that affect the generation of such irregularities.

  13. Ionospheric effects during severe space weather events seen in ionospheric service data products

    NASA Astrophysics Data System (ADS)

    Jakowski, Norbert; Danielides, Michael; Mayer, Christoph; Borries, Claudia

    Space weather effects are closely related to complex perturbation processes in the magnetosphere-ionosphere-thermosphere systems, initiated by enhanced solar energy input. To understand and model complex space weather processes, different views on the same subject are helpful. One of the ionosphere key parameters is the Total Electron Content (TEC) which provides a first or-der approximation of the ionospheric range error in Global Navigation Satellite System (GNSS) applications. Additionally, horizontal gradients and time rate of change of TEC are important for estimating the perturbation degree of the ionosphere. TEC maps can effectively be gener-ated using ground based GNSS measurements from global receiver networks. Whereas ground based GNSS measurements provide good horizontal resolution, space based radio occultation measurements can complete the view by providing information on the vertical plasma density distribution. The combination of ground based TEC and vertical sounding measurements pro-vide essential information on the shape of the vertical electron density profile by computing the equivalent slab thickness at the ionosonde station site. Since radio beacon measurements at 150/400 MHz are well suited to trace the horizontal structure of Travelling Ionospheric Dis-turbances (TIDs), these data products essentially complete GNSS based TEC mapping results. Radio scintillation data products, characterising small scale irregularities in the ionosphere, are useful to estimate the continuity and availability of transionospheric radio signals. The different data products are addressed while discussing severe space weather events in the ionosphere e.g. events in October/November 2003. The complementary view of different near real time service data products is helpful to better understand the complex dynamics of ionospheric perturbation processes and to forecast the development of parameters customers are interested in.

  14. Generation of ionospheric ducts by the HAARP HF heater

    Microsoft Academic Search

    J. A. Cohen; R. Pradipta; L. M. Burton; A. Labno; M. C. Lee; B. J. Watkins; C. Fallen; S. P. Kuo; W. J. Burke; D. Mabius; B. Z. See

    2010-01-01

    We report an investigation of ionospheric ducts having the shape of large plasma sheets, generated by vertically transmitted HAARP HF heater waves in several experiments conducted in Gakona, Alaska. Theory predicts that O-mode heater wave-created ionospheric ducts form parallel-plate waveguides within the meridional plane, and those generated by the X-mode heater waves are orthogonal to the meridional plane. Our theoretical

  15. A thermosphere-ionosphere nested grid (TING) model

    Microsoft Academic Search

    Wenbin Wang

    1998-01-01

    A three-dimensional, time dependent, nested grid model has been developed to study mesoscale processes in the coupled thermosphere-ionosphere system. This new Thermosphere-Ionosphere Nested Grid (TING) Model, which builds up on the existing and well proven NCAR-TIGCM, calculates simultaneously global (coarse resolution) and local (high resolution) distributions of the neutral and plasma winds, temperatures, and composition. It is comprised of two

  16. A numerical simulation of the geomagnetic sudden commencement: 2. Plasma processes in the main impulse

    NASA Astrophysics Data System (ADS)

    Fujita, S.; Tanaka, T.; Kikuchi, T.; Fujimoto, K.; Itonaga, M.

    2003-12-01

    A geomagnetic sudden commencement (SC) is studied numerically based on a model of buffeting the magnetosphere by a solar wind density impulse. This paper treats two successive current systems in the main impulse (MI) phase. The two current systems have different current generating mechanisms. The first current generator appears behind the wavefront of a compressional disturbance launched by the impulse. The inertia current of the compressional mode is generated by free energy due to deceleration of plasma flows. A field-aligned current (FAC) is excited through mode conversion from the compressional wave in a VA gradient region. The magnetospheric flows and the ionospheric flows are not connected self-consistently to each other. The second generator is located in the tailward side of the cusp. It is the same as the generator of the region 1 current system. The current generated there is connected with the FAC with the region 1 sense via a diamagnetic current flowing around an isolated enhancement of pressure in the nightside equatorial magnetosphere. The pressure enhancement is induced through compression of the magnetospheric flank due to the solar wind impulse. In this period, plasma convection vortices appear both in the magnetosphere and in the ionosphere, which are correspondent to each other. This is a peculiar convection confined within the magnetosphere (the SC transient cell convection). This convection is driven though compression of the magnetospheric flank due to the solar wind impulse.

  17. Convection in Neptune's magnetosphere

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  18. Studies of Strong Langmuir Turbulence at the HAARP Ionospheric Observatory

    Microsoft Academic Search

    J. P. Sheerin; M. E. Bacon; J. M. Gerres; B. J. Watkins; W. A. Bristow; S. I. Oyama; C. J. Heinselman

    2008-01-01

    High power HF transmitters have induced a number of plasma instabilities in the interaction region of overdense ionospheric plasma. We report results from a series of such experiments using over one gigawatt of HF power (ERP) in comprehensive studies of strong Langmuir turbulence (SLT) and particle acceleration at the HAARP Observatory, Gakona, Alaska. Among the effects observed and studied are:

  19. Mantle Convection

    NSDL National Science Digital Library

    H. Schmeling

    This page discusses thermal convection as it applies to the Earth's mantle and includes three QuickTime movies for three different cases of convection: heating from below, heating from within, and a combination of the two.

  20. Experimental evidence of electromagnetic pollution of ionosphere

    NASA Astrophysics Data System (ADS)

    Pronenko, Vira; Korepanov, Valery; Dudkin, Denis

    The Earth’s ionosphere responds to external perturbations originated mainly in the Sun, which is the primary driver of the space weather (SW). But solar activity influences on the ionosphere and the Earth's atmosphere (i.e., the energy transfer in the direction of the Sun-magnetosphere-ionosphere-atmosphere-surface of the Earth), though important, is not a unique factor affecting its state - there is also a significant impact of the powerful natural and anthropogenic processes, which occur on the Earth’s surface and propagating in opposite direction along the Earth’s surface-atmosphere-ionosphere-magnetosphere chain. Numerous experimental data confirm that the powerful sources and consumers of electrical energy (radio transmitters, power plants, power lines and industrial objects) cause different ionospheric phenomena, for example, changes of the electromagnetic (EM) field and plasma in the ionosphere, and affect on the state of the Earth atmosphere. Anthropogenic EM effects in the ionosphere are already observed by the scientific satellites and the consequences of their impact on the ionosphere are not currently known. Therefore, it is very important and urgent task to conduct the statistically significant research of the ionospheric parameters variations due to the influence of the powerful man-made factors, primarily owing to substantial increase of the EM energy production. Naturally, the satellite monitoring of the ionosphere and magnetosphere in the frequency range from tens of hertz to tens of MHz with wide ground support offers the best opportunity to observe the EM energy release, both in the global and local scales. Parasitic EM radiation from the power supply lines, when entering the ionosphere-magnetosphere system, might have an impact on the electron population in the radiation belt. Its interaction with trapped particles will change their energy and pitch angles; as a result particle precipitations might occur. Observations of EM emission by multiple low orbiting satellites have confirmed a significant increase in their intensity over the populated areas of Europe and Asia. Recently, there are many experimental evidences of the existence of power line harmonic radiation (PLHR) in the ionosphere. Their spectra consist of succession of 50 (60) Hz harmonics which is accompanied by a set of lines separated by 50 (60) or 100 (120) Hz - the central frequency of which is shifted to high frequency. These lines cover rather wide band - according to the available experimental data, their central frequencies are observed from ~1.5 - 3 kHz up to 15 kHz, and recently the main mains frequencies are also observed. The examples of power line harmonic radiation, which were detected by “Sich-1M”, “Chibis-M” and “Demeter” satellites, have been presented and discussed. The available experimental data, as well as theoretical estimations, allow us with a high degree of certainty to say that the permanent satellite monitoring of the ionospheric and magnetospheric anthropogenic EM perturbations is necessary for: a) objective assessment and prediction of the space weather conditions; b) evaluation of the daily or seasonal changes in the level of energy consumption; c) construction of a map for estimation of near space EM pollution. This study is partially supported by SSAU contract N 4-03/13.

  1. Ground based and satellite simultaneous observations of Medium Scale Travelling Ionospheric Disturbances

    Microsoft Academic Search

    T. Onishi; T. Tsugawa; Y. Otsuka; J.-J. Berthelier

    2009-01-01

    Medium-scale Traveling Ionospheric Disturbances (MSTIDs) are considered as an ionospheric manifestation of Atmospheric Gravity Waves (AGWs). Daytime MSTIDs are generated by the ion-neutral collisions in the F-region and it has been considered that plasma disturbances at the top-side ionosphere might be too small for satellite observations. In this presentation, we present simultaneous observations of daytime MSTIDs over North America, using

  2. A Review of Low Frequency Electromagnetic Wave Phenomena Related to Tropospheric-Ionospheric Coupling Mechanisms

    NASA Technical Reports Server (NTRS)

    Simoes, Fernando; Pfaff, Robert; Berthelier, Jean-Jacques; Klenzing, Jeffrey

    2012-01-01

    Investigation of coupling mechanisms between the troposphere and the ionosphere requires a multidisciplinary approach involving several branches of atmospheric sciences, from meteorology, atmospheric chemistry, and fulminology to aeronomy, plasma physics, and space weather. In this work, we review low frequency electromagnetic wave propagation in the Earth-ionosphere cavity from a troposphere-ionosphere coupling perspective. We discuss electromagnetic wave generation, propagation, and resonance phenomena, considering atmospheric, ionospheric and magnetospheric sources, from lightning and transient luminous events at low altitude to Alfven waves and particle precipitation related to solar and magnetospheric processes. We review in situ ionospheric processes as well as surface and space weather phenomena that drive troposphere-ionosphere dynamics. Effects of aerosols, water vapor distribution, thermodynamic parameters, and cloud charge separation and electrification processes on atmospheric electricity and electromagnetic waves are reviewed. We also briefly revisit ionospheric irregularities such as spread-F and explosive spread-F, sporadic-E, traveling ionospheric disturbances, Trimpi effect, and hiss and plasma turbulence. Regarding the role of the lower boundary of the cavity, we review transient surface phenomena, including seismic activity, earthquakes, volcanic processes and dust electrification. The role of surface and atmospheric gravity waves in ionospheric dynamics is also briefly addressed. We summarize analytical and numerical tools and techniques to model low frequency electromagnetic wave propagation and solving inverse problems and summarize in a final section a few challenging subjects that are important for a better understanding of tropospheric-ionospheric coupling mechanisms.

  3. Verification of ionospheric sensors

    NASA Astrophysics Data System (ADS)

    Coker, Clayton; Kronschnabl, Glenn; Coco, David S.; Bust, Gary S.; Gaussiran, Thomas L., II

    2001-01-01

    Ionospheric products from sensors and models were compared to investigate strengths and limitations of each. Total electron content data from computerized ionospheric tomography (CIT) and TOPEX sensors in the Caribbean region in 1997 were compared to estimates produced by models Parameterized Ionospheric Model (PIM) and Raytrace/ICED-Bent-Gallagher (RIBG) and global maps from GPS. A 5 total electron content unit (TECU) bias was observed in TOPEX. CIT and TOPEX confirmed the location and structure of the equatorial anomaly. A GPS map confirmed the location of the anomaly but did not reproduce structure less than 1000 km in latitude and 1500 km in longitude and underestimated TEC by at least 11 TECU or 25%. PIM positioned the anomaly 13° equatorward of its observed location and greatly underestimated (˜50%) the rise in content over 5°-25°N range. RIBG overestimated the latitudinal extent of the anomaly and underestimated TEC at the peak by 40%. Additional comparisons were made using CIT and ionosonde sensors at midlatitude during the summer of 1998. Fourteen days of TEC, hmF2, NmF2, and half-thickness comparisons showed reasonable agreement between CIT and ionosonde for TEC and NmF2. The hmF2 and half-thickness comparisons were contaminated by noise, which accounted for a significant portion of the ionospheric variation. Daytime cases where CIT overestimated maximum density were attributed to underestimating layer thickness. Finally, TOPEX and multiple GPS sensors were compared to verify regional ionospheric conditions associated with occurrence of nighttime ionospheric depletions in the Caribbean during Combined Ionospheric Campaigns in June of 1998. From 0300 to 0800 UT on June 26, GPS and TOPEX showed elevated nighttime content over the entire Caribbean region. Vertical TEC approached 25 TECU in some places with interspersed depletions, which in some cases evacuated nearly the entire ionospheric content.

  4. Inertial currents in isotropic plasma

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    The magnetospheric convection electric field contributes to Birkeland currents. The effects of the field are to polarize the plasma by displacing the bounce paths of the ions from those of electrons, to redistribute the pressure so that it is not constant along magnetic field lines, and to enhance the pressure gradient by the gradient of the bulk speed. Changes in the polarization charge during the convection of the plasma are neutralized by electrons in the form of field-aligned currents that close through the ionosphere. The pressure drives field-aligned currents through its gradient in the same manner as in quasi-static plasmas, but with modifications that are important if the bulk speed is of the order of the ion thermal speed; the variations in the pressure along field lines are maintained by a weak parallel potential drop. These effects are described in terms of the field-aligned currents in steady state, isotropic, MHD plasma. Solutions are developed by taking the MHD limit ot two-fluid solutions and illustrated in the special case of Maxwellian plasma for which the temperature is constant along magnetic field lines. The expression for the Birkeland current density is a generalization of Vasyliunas' expression for the field-aligned current density in quasi-static plasma and provides a unifying expression when both pressure gradients and ion inertia operate simultaneously as sources of field-aligned currents. It contains a full account of different aspects of the ion flow (parallel and perpendicular velocity and vorticity) that contribute to the currents. Contributions of ion inertia to field-aligned currents will occur in regions of strong velocity shear, electric field reversal, or large gradients in the parallel velocity or number density, and may be important in the low-latitude boundary layer, plasma sheet boundary layer, and the inner edge region of the plasma sheet.

  5. Convective radial energy flux due to resonant magnetic perturbations and magnetic curvature at the tokamak plasma edge

    SciTech Connect

    Marcus, F. A., E-mail: albertus@if.usp.br [Institute of Physics at University of São Paulo, C.P. 66318, 05315-970 São Paulo, S.P. (Brazil); Aix-Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Beyer, P.; Fuhr, G.; Monnier, A.; Benkadda, S. [Aix-Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France)

    2014-08-15

    With the resonant magnetic perturbations (RMPs) consolidating as an important tool to control the transport barrier relaxation, the mechanism on how they work is still a subject to be clearly understood. In this work, we investigate the equilibrium states in the presence of RMPs for a reduced MHD model using 3D electromagnetic fluid numerical code with a single harmonic RMP (single magnetic island chain) and multiple harmonics RMPs in cylindrical and toroidal geometry. Two different equilibrium states were found in the presence of the RMPs with different characteristics for each of the geometries used. For the cylindrical geometry in the presence of a single RMP, the equilibrium state is characterized by a strong convective radial thermal flux and the generation of a mean poloidal velocity shear. In contrast, for toroidal geometry, the thermal flux is dominated by the magnetic flutter. For multiple RMPs, the high amplitude of the convective flux and poloidal rotation are basically the same in cylindrical geometry, but in toroidal geometry the convective thermal flux and the poloidal rotation appear only with the islands overlapping of the linear coupling between neighbouring poloidal wavenumbers m, m – 1, and m?+?1.

  6. Tsunami Ionospheric warning and Ionospheric seismology

    NASA Astrophysics Data System (ADS)

    Lognonne, Philippe; Rolland, Lucie; Rakoto, Virgile; Coisson, Pierdavide; Occhipinti, Giovanni; Larmat, Carene; Walwer, Damien; Astafyeva, Elvira; Hebert, Helene; Okal, Emile; Makela, Jonathan

    2014-05-01

    The last decade demonstrated that seismic waves and tsunamis are coupled to the ionosphere. Observations of Total Electron Content (TEC) and airglow perturbations of unique quality and amplitude were made during the Tohoku, 2011 giant Japan quake, and observations of much lower tsunamis down to a few cm in sea uplift are now routinely done, including for the Kuril 2006, Samoa 2009, Chili 2010, Haida Gwai 2012 tsunamis. This new branch of seismology is now mature enough to tackle the new challenge associated to the inversion of these data, with either the goal to provide from these data maps or profile of the earth surface vertical displacement (and therefore crucial information for tsunami warning system) or inversion, with ground and ionospheric data set, of the various parameters (atmospheric sound speed, viscosity, collision frequencies) controlling the coupling between the surface, lower atmosphere and the ionosphere. We first present the state of the art in the modeling of the tsunami-atmospheric coupling, including in terms of slight perturbation in the tsunami phase and group velocity and dependance of the coupling strength with local time, ocean depth and season. We then show the confrontation of modelled signals with observations. For tsunami, this is made with the different type of measurement having proven ionospheric tsunami detection over the last 5 years (ground and space GPS, Airglow), while we focus on GPS and GOCE observation for seismic waves. These observation systems allowed to track the propagation of the signal from the ground (with GPS and seismometers) to the neutral atmosphere (with infrasound sensors and GOCE drag measurement) to the ionosphere (with GPS TEC and airglow among other ionospheric sounding techniques). Modelling with different techniques (normal modes, spectral element methods, finite differences) are used and shown. While the fits of the waveform are generally very good, we analyse the differences and draw direction of future studies and improvements, enabling the integration of lateral variations of the solid earth, bathymetry or atmosphere, finite model sources, non-linearity of the waves and better attenuation and coupling processes. All these effects are revealed by phase or amplitude discrepancies in selected observations. We then present goals and first results of source inversions, with a focus on estimations of the sea level uplift location and amplitude, either by using GPS networks close from the epicentre or, for tsunamis, GPS of the Hawaii Islands.

  7. Model of Jovian F region ionosphere (Jovian ionosphere model in offset dipole approximation)

    NASA Technical Reports Server (NTRS)

    Tan, A.

    1990-01-01

    The geomagnetic control of the Earth's atmosphere is well understood. In the F-region and the topside ionosphere, non-electrical forces transport plasma along the magnetic field lines only. In consequence, the worldwide distribution of ionization is strongly dependent on the dip angle. For example, the equatorial anomaly is roughly symmetrical about the dipole equator rather than the geographic. The same appears to be the case in the Jovian ionosphere (Mahajan, 1981). The influence of the magnetic field of Jupiter on its ionization pattern is one of several outstanding topics which need to be studied. Tan (1986) investigated the formation of the equatorial anomaly in the Jovian ionosphere under a centered dipole model. Tan (1988) further studied the effect of the tilt of the Jovian dipole. The results were in broad agreement with those of a diffusive equilibrium model (Tan and Wu, 1981). An off-centered dipole model is constructed and its effects on the ionization pattern are investigated.

  8. The Flow of Plasma in the Solar-Terrestrial Environment

    NASA Technical Reports Server (NTRS)

    Schunk, Robert W.; Sojka, Jan J.; Barakat, Abdallah R.; Demars, Howard G.; Zhu, Lie

    2005-01-01

    The overall goal of our NASA theory research is to trace the flow of mass, momentum, and energy through the magnetosphere-ionosphere-atmosphere system taking into account the coupling, time delays, and feedback mechanisms that are characteristic of the system. Our approach is to model the magnetosphere-ionosphere-atmosphere (M-I-A) system in a self-consistent quantitative manner using unique global models that allow us to study the coupling between the different regions on a range of spatial and temporal scales. The uniqueness of our global models stems from their high spatial and temporal resolutions, the physical processes included, and the numerical techniques employed. Currently, we have time-dependent global models of the ionosphere, thermosphere, polar wind, plasmasphere, and electrodynamics. It is now becoming clear that a significant fraction of the flow of mass, momentum, and energy in the M-I-A system occurs on relatively small spatial scales. Therefore, an important aspect of our NASA Theory program concerns the effect that mesoscale (100-l000 km) density structures have on the macroscopic flows in the ionosphere, thermosphere, and polar wind. The structures can be created either by structured magnetospheric inputs (i.e., structured electric field, precipitation, or Birkeland current patterns) or by time variations of these inputs due to geomagnetic storms and substorms. Some of the mesoscale structures of interest include sun-aligned polar cap arcs, propagating plasma patches, traveling convection vortices, subauroral ion drift (SAID) channels, gravity waves, and the polar hole.

  9. Sputnik 1 and the First Satellite Ionospheric Experiment

    NASA Astrophysics Data System (ADS)

    Sinelnikov, Vyacheslav; Kuznetsov, Vladimir; Alpert, Svetlana

    The world's first scientific space experiment was carried out in 1957 during the flight of the first Artificial Earth Satellite (AES) - Sputnik 1. It was an ionospheric experiment performed at IZMIRAN under the direction of Prof. Ya.L.Alpert (1911-2010). The sunrise and sunset variations in the AES radio signal were recorded in order to determine the distribution of electron density in the topside ionosphere (above the maximum). The experiment demonstrated the capabilities of the satellite radio beacon method, which is now very important and widely used for studying the ionosphere. Our report submitted to the COSPAR General Assembly in Russia describes the history and results of that experiment, as well as some other contributions by Ya.L.Alpert to ionospheric research. Yakov L.Alpert was one of the most famous and influential radiophysicists of his time, the author of many fundamental studies and of a number of classic books on the theory of propagation of electromagnetic waves, interaction of artificial bodies with ionospheric plasmas, ionospheric radio scattering, and the use of satellite radio beacon methods for studying the ionosphere.

  10. All Ionospheres are not Alike: Reports from other Planets

    NASA Technical Reports Server (NTRS)

    Nagy, Andrew F.; Cravens, Thomas E.; Waite, H. J., Jr.

    1995-01-01

    Our understanding of planetary ionospheres made some progress during the last four years. Most of this progress was due to new and/or improved theoretical models, although some new data were also obtained by direct and remote sensing observations. The very basic processes such as ionization, chemical transformations and diffusive as well as convective transports are analogous in all ionospheres; the major differences are the result of factors such as different neutral atmospheres, intrinsic magnetic field strength, distance from the Sun, etc. Improving our understanding of any of the ionospheres in our solar system helps in elucidating the controlling physical and chemical processes in all of them. New measurements are needed to provide new impetus, as well as guidance, in advancing our understanding and we look forward to such information in the years ahead.

  11. Numerical validations of neural-network-based ionospheric tomography for disturbed ionospheric conditions and sparse data

    NASA Astrophysics Data System (ADS)

    Hirooka, S.; Hattori, K.; Takeda, T.

    2011-10-01

    Three-dimensional ionospheric tomography is effective for investigations of the dynamics of ionospheric phenomena. However, it is an ill-posed problem in the context of sparse data, and accurate electron density reconstruction is difficult. The Residual Minimization Training Neural Network (RMTNN) tomographic approach, a multilayer neural network trained by minimizing an objective function, allows reconstruction of sparse data. In this study, we validate the reconstruction performance of RMTNN using numerical simulations based on both sufficiently sampled and sparse data. First, we use a simple plasma-bubble model representing the disturbed ionosphere and evaluate the reconstruction performance based on 40 GPS receivers in Japan. We subsequently apply our approach to a sparse data set obtained from 24 receivers in Indonesia. The reconstructed images from the disturbed and sparse data are consistent with the model data, except below 200 km altitude. To improve this performance and limit any discrepancies, we used information on the electron density in the lower ionosphere. The results suggest the restricted RMTNN-tomography-assisted approach is very promising for investigations of ionospheric electron density distributions, including studies of irregular structures in different regions. In particular, RMTNN constrained by low-Earth-orbit satellite data is effective in improving the reconstruction accuracy.

  12. Plasma jets and plasma bullets

    Microsoft Academic Search

    M G Kong; B N Ganguly; R F Hicks

    2012-01-01

    Plasma plumes, or plasma jets, belong to a large family of gas discharges whereby the discharge plasma is extended beyond the plasma generation region into the surrounding ambience, either by a field (e.g. electromagnetic, convective gas flow, or shock wave) or a gradient of a directionless physical quantity (e.g. particle density, pressure, or temperature). This physical extension of a plasma

  13. The Comprehensive Inner Magnetosphere-Ionosphere Model

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  14. New techniques in ionospheric sounding and studies

    NASA Astrophysics Data System (ADS)

    Reinisch, B. W.

    An overview is given of new techniques in ionospheric sounding and studies. Rapid progress in the integrated circuit market has led to new advanced techniques in the remote probing of the ionosphere with HF radio waves. The classical ionosonde which measured virtual height as a function of frequency has been expanded into a geophysical research tool by measuring all the observables contained in the electromagnetic signals reflected from the ionosphere: amplitude, phase, Doppler, incidence angle, and polarization. A receiving antenna array and high-speed digital processing provide the desired spatial and temporal resolution. The current emphasis is on the on-line and off-line post-processing of the multiparameter ionogram data to extract the geophysically important ionospheric characteristics: the vertical electron density profiles, horizontal gradients (tilts and waves), plasma drift, the mid-latitude F-region trough, and auroral and equatorial spread F. Digital ionosondes deployed in the polar cap and the auroral zone have helped to obtain a better understanding of some of the high latitude features, and measurements of the equatorial spread F show the development and motion of the F-region bubbles. HF coherent radar techniques which measure the velocity of irregularities with scale sizes of one half the radio wavelength have been used mainly in the northern auroral zone.

  15. Global Response to Local Ionospheric Mass Ejection

    NASA Technical Reports Server (NTRS)

    Moore, T. E.; Fok, M.-C.; Delcourt, D. C.; Slinker, S. P.; Fedder, J. A.

    2010-01-01

    We revisit a reported "Ionospheric Mass Ejection" using prior event observations to guide a global simulation of local ionospheric outflows, global magnetospheric circulation, and plasma sheet pressurization, and comparing our results with the observed global response. Our simulation framework is based on test particle motions in the Lyon-Fedder-Mobarry (LFM) global circulation model electromagnetic fields. The inner magnetosphere is simulated with the Comprehensive Ring Current Model (CRCM) of Fok and Wolf, driven by the transpolar potential developed by the LFM magnetosphere, and includes an embedded plasmaspheric simulation. Global circulation is stimulated using the observed solar wind conditions for the period 24-25 Sept 1998. This period begins with the arrival of a Coronal Mass Ejection, initially with northward, but later with southward interplanetary magnetic field. Test particles are launched from the ionosphere with fluxes specified by local empirical relationships of outflow to electrodynamic and particle precipitation imposed by the MIlD simulation. Particles are tracked until they are lost from the system downstream or into the atmosphere, using the full equations of motion. Results are compared with the observed ring current and a simulation of polar and auroral wind outflows driven globally by solar wind dynamic pressure. We find good quantitative agreement with the observed ring current, and reasonable qualitative agreement with earlier simulation results, suggesting that the solar wind driven global simulation generates realistic energy dissipation in the ionosphere and that the Strangeway relations provide a realistic local outflow description.

  16. Charged particles in Titan's ionosphere

    NASA Astrophysics Data System (ADS)

    Tripathi, Sachchida

    2010-05-01

    Charged particles in Titan's ionosphere Marykutty Michael1, Sachchida Nand Tripathi1,2,3, Pratima Arya1 1Indian Institute of Technology Kanpur 2Oak Ridge Associated Universities 3NASA Goddard Space Flight Center Observations by two instruments onboard the Cassini spacecraft, Ion Neutral Mass Spectrometer (INMS) and CAssini Plasma Spectrometer (CAPS), revealed the existence of heavy hydrocarbon and nitrile species with masses of several thousand atomic mass units at altitudes of 950 - 1400 km in the atmosphere of Titan (Waite et al., 2007; Crary et al., 2009). Though these particles were believed to be molecules, they are most likely aerosols formed by the clumping of smaller molecules (Waite et al., 2009). These particles were estimated to have a density of 10-3 kg m-3 and a size of up to 256 nm. The existence of very heavy ions has also been observed by the CAPS components with a mass by charge ratio of up to 10000 (Coates et al., 2007, 2009; Sittler et al., 2009). The goal of this paper is to find out whether the so called heavy ions (or charged particles) are generated by the charge transfer of ions and electrons to the particles. The charging of these particles has been studied by using the charge balance equations that include positive ions, negative ions, electrons, neutral and charged particles. Information on the most abundant ion clusters are obtained from Vuitton et al., (2009) and Wilson and Atreya, (2004). Mass by charge ratio thus calculated will be compared with those observed by Coates et al. (2007). References: Coates AJ, et al., Discovery of heavy negative ions in Titan's ionosphere, Geophys. Res. Lett., 34:L22103, 2007. Coates AJ, et al., Heavy negative ions in titan's ionosphere: altitude and latitude dependence. Planet. Space Sci., doi:10.1016/j.pss.2009.05.009, 2009. Crary F.J., et al., Heavy ions, temperatures and winds in titan's ionosphere: Combined cassini caps and inms observations. Planet. Space Sci., doi:10.1016/j.pss.2009.09.006, 2009. Sittler,E.C. et al., Heavy ion formation in Titan's ionosphere: Magnetospheric introduction of free oxygen and a source of Titan's aerosols? Planet. Space Sci., doi:10.1016/j.pss.2009.07.017, 2009. Vuitton, V., Negative ion chemistry in Titan's upper atmosphere, Planet. Space Sci., doi:10.1016/j.pss.2009.04.004, 2009. Waite J.H, et al., The process of tholin formation in Titan's upper atmosphere. Science, doi: 10.1126/science.1139727, 316, 870, 2007. Waite JH, et al., High altitude production of Titan's aerosols, In Titan from Cassini-Huygens, edited by RH. Brown, J.P Lebreton, JH Waite, Springer, 2009. Wilson, E.H. and S. Atreya, Current state of modeling the photochemistry of Titan's mutually dependent atmosphere and ionosphere, J. Geophys. Res., 109, E06002, doi:10.1029/2003JE002181, 2004.

  17. Regional ionospheric TEC modelling; working towards mapping Africa's ionosphere

    Microsoft Academic Search

    John Bosco Habarulema; Lee-Anne McKinnell; Ben Opperman

    2011-01-01

    Currently the available data over the African continent does not allow for the construction of a truly representative ionospheric map for the purposes of long term predictions. In addition, the forecasting of the ionospheric variability over long term is a complicated task. This is because the ionospheric medium is continuously changing, it exhibits behavior that is not easily predictable and

  18. Crossed magnetic field gas breakdown around a cylindrical spacecraft in the ionosphere

    Microsoft Academic Search

    Mengu Cho

    1993-01-01

    Gas breakdown voltages are calculated for a cylindrical spacecraft in the ionosphere, whose axis is parallel to the geomagnetic field. The Townsend breakdown criterion is applied to the neutral gas of 1017-1020 m-3 surrounding the cylindrical spacecraft, which is assumed to have a highly negative potential with respect to the ionospheric plasma. Electrons are emitted from the surface and ionize

  19. Cassini detection of Enceladus' cold water-group plume ionosphere R. L. Tokar,1

    E-print Network

    Johnson, Robert E.

    Cassini detection of Enceladus' cold water-group plume ionosphere R. L. Tokar,1 R. E. Johnson,2 M reports direct detection by the Cassini plasma spectrometer of freshly-produced water-group ions (O+ , OH. Jones, and C. S. Paty (2009), Cassini detection of Enceladus' cold water-group plume ionosphere, Geophys

  20. Origin of the main auroral oval in Jupiter's coupled magnetosphere–ionosphere system

    Microsoft Academic Search

    S. W. H. Cowley; E. J. Bunce

    2001-01-01

    We show that the principal features of the main auroral oval in the jovian system are consistent with an origin in the magnetosphere–ionosphere coupling currents associated with the departure of the plasma from rigid corotation in the middle magnetosphere, specifically with the inner region of field-aligned current directed upwards from the ionosphere to the magnetosphere. The features we refer to

  1. Negative Effect on Electron Density in Midlatitude Ionosphere due to Geomagnetic Disturbances: FORMOSAT-3\\/COSMIC Observations

    Microsoft Academic Search

    S. W. Tam; C. Chen; K. Wang

    2009-01-01

    The ionospheric plasma usually responds drastically to severe space weather conditions, signified by strong magnetic field disturbances in the near-Earth environment. The level of disturbances is often well characterized by global indices such as Kp and Dst. Our statistical studies examine the ionospheric vertical electron density profiles under different levels of geomagnetic activities, as characterized by such indices. The studies

  2. Did Tsunami-Launched Gravity Waves Trigger Ionospheric Turbulence over Arecibo?

    Microsoft Academic Search

    R. Pradipta; W. J. Burke; A. Labno; L. M. Burton; J. A. Cohen; S. E. Dorfman; S. P. Kuo

    2008-01-01

    We report on measurements of ionospheric plasma dynamics conducted at the Arecibo Observatory between 20:00 and 24:00 local time (LT) on December 25 and 26, 2004 using the 430 MHz incoherent scatter radar (ISR). For interpretive purposes these measurements are supported by data from two nearby ionosondes and Global Positioning System (GPS) satellites. The ISR detected different ionospheric behaviors during

  3. Titan's ionosphere: Model comparisons with Cassini Ta data T. E. Cravens,1

    E-print Network

    California at Berkeley, University of

    Titan's ionosphere: Model comparisons with Cassini Ta data T. E. Cravens,1 I. P. Robertson,1 J 2005. [1] On October 26, 2004, during its first encounter with Titan (Ta), the Cassini Orbiter moved of the main part of Titan's ionosphere were made by the Langmuir probe on the Cassini Radio and Plasma Wave

  4. Ultra-low-frequency electrodynamics of the magnetosphere-ionosphere interaction

    E-print Network

    Ultra-low-frequency electrodynamics of the magnetosphere-ionosphere interaction A. V. Streltsov than the fundamental eigenfrequency of the magnetosphere measured in the regions where the ionospheric Alfve´n waves in the highly inhomogeneous magnetospheric plasma and interaction between these waves

  5. A physical mechanism of positive ionospheric storms at low latitudes and midlatitudes

    Microsoft Academic Search

    N. Balan; K. Shiokawa; Y. Otsuka; T. Kikuchi; D. Vijaya Lekshmi; S. Kawamura; M. Yamamoto; G. J. Bailey

    2010-01-01

    A physical mechanism of the positive ionospheric storms at low latitudes and midlatitudes is presented through multi-instrument observations, theoretical modeling, and basic principles. According to the mechanism, an equatorward neutral wind is required to produce positive ionospheric storms. The mechanical effects of the wind (1) reduce (or stop) the downward diffusion of plasma along the geomagnetic field lines, (2) raise

  6. Robust detection of ionospheric irregularities

    NASA Technical Reports Server (NTRS)

    Walter, T.; Hansen, A.; Blanch, J.; Enge, P.; Mannucci, T.; Pi, X.; Sparks, L.; Iijima, B.; El-Arini, B.; Lejeune, R.; Hagen, M.; Altshuler, E.; Fries, R.; Chu, A.

    2000-01-01

    The approach outlined in this paper conservatively bounds the ionospheric errors even for the worst observed ionospheric conditions to date, using data sets taken from the operational receivers in the WAAS reference station network.

  7. Climatology of GNSS ionospheric scintillation at high latitudes

    NASA Astrophysics Data System (ADS)

    Spogli, L.; Alfonsi, L.; de Franceschi, G.; Romano, V.; Aquino, M.; Dodson, A.; Mitchell, C. N.

    2009-12-01

    Under perturbed conditions caused by intense solar wind magnetosphere coupling, the ionosphere may become highly turbulent and irregularities, typically enhancements or depletions of the electron density embedded in the ambient ionosphere, can form. Such irregularities cause diffraction effects, mainly due to the random fluctuations of the refractive index of the ionosphere, on the satellites signals passing through them and consequent perturbations may cause GNSS navigation errors and outages, abruptly corrupting its performance. Due to the morphology of the geomagnetic field, whose lines are almost vertical at high latitude, polar areas are characterized by the presence of significant ionospheric irregularities having scale sizes ranging from hundreds of kilometers down to a few centimeters and with highly dynamic structures. The understanding of the effect of such phenomena is important, not only in preparation for the next solar cycle (24), whose maximum is expected in 2012, but also for a deeper comprehension of the dynamics of the high-latitude ionosphere. We analyze the fluctuations in the carrier frequency of the radio waves received on the ground, commonly referred to as ionospheric amplitude and phase scintillations, to investigate the physical processes causing them. The phase scintillations on GNSS signals are likely caused by ionospheric irregularities of scale size of hundreds of meters to few kilometers. The amplitude scintillations on GNSS signals are caused by ionospheric irregularities of scale size smaller than the Fresnel radius, which is of the order of hundreds of meters for GNSS signals, typically embedded into the patches. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Institute of Engineering Surveying and Space Geodesy (IESSG) of the University of Nottingham manage the same kind of GISTM (GPS Ionospheric Scintillation and TEC Monitor) receivers over the European high and mid latitude regions and over Antarctica. The GISTM receivers consist of NovAtel OEM4 dual-frequency receivers with special firmware specifically able to compute in near real time the amplitude and the phase scintillation from the GPS L1 frequency signals, and the ionospheric TEC (Total Electron Content) from the GPS L1 and L2 carrier phase signals. From this ground-based network, we are able to capture the dynamics of ionospheric plasma in a wide latitudinal range, from auroral to cusp/cap regions, considering the contribution of both hemispheres, in a bi-polar framework. The data collection started in 2001 and is still in progress. The results, obtained by statistically analyzing a large data sample over a wide period, show the effect of ionospheric disturbances on the GNSS signals, evidencing the different contributions of the auroral and the cusp/cap ionosphere and highlighting possible scintillation scenarios over polar regions.

  8. Mercury and Mars - The role of ionospheric conductivity in the acceleration of magnetospheric particles

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    Although Mercury and Mars appear to have magnetospheres of comparable size, Mercury's magnetosphere accelerates charged particles, whereas Mars' magnetosphere apparently does not. We propose that this difference results from the fact that rapid steady-state convection, and the associated particle acceleration, cannot occur in a Martian magnetosphere because of its connection to a highly conducting ionosphere. Mercury, which has no conducting ionosphere and probably an insufficiently conducting surface, can exhibit rapid solar-wind-induced convection and hence particle acceleration in its magnetospheric tail.

  9. Self-consistent particle and parallel electrostatic field distributions in the magnetospheric-ionospheric auroral region

    Microsoft Academic Search

    Y. T. Chiu; Michael Schulz

    1978-01-01

    The variation of the self-consistent electrostatic potential along the magnetic field is calculated by application of the principle of quasi-neutrality to the plasma components distributed along an auroral field line. The equilibrium plasma consists of hot anisotropic magnetospheric plasma, ionospheric plasma evaporated or extracted upward by the parallel electrostatic field, and backscattered electrons. It is shown that the above charged

  10. Ionospheric scintillation over Antarctica during the storms of 2010

    NASA Astrophysics Data System (ADS)

    Mitchell, C.; Kinrade, J.; Yin, P.; Smith, N.; Bust, G. S.; Weatherwax, A. T.; Rose, M.; Maxfield, D.; Jarvis, M. J.

    2011-12-01

    At the present time our knowledge of the Earth's ionosphere is dominated by measurements from the Northern Hemisphere. In spite of recent evidence indicating unexplained differences in the ionospheres from the two hemispheres, there is still very little information from the ionosphere over the Southern oceans and the Antarctic. Although the Antarctic is rather sparsely instrumented for ionospheric study, over the past decade increasing numbers of geodetic GPS receivers have been deployed there and more recently several groups have installed specialist GPS equipment for monitoring scintillation. In January 2010 a project commenced that involved the remote deployment of equipment at 81 degrees and 89 degrees South geographic. The objective of the fieldwork was to deploy GPS receiving equipment that would for the first time take simultaneous measurements of total electron content (TEC), plasma velocity and ionospheric scintillation at remote locations across the Antarctic. The paper reports on the results from the first year of data collection throughout three ionospheric storms. The first storm shows a multitude of small-scale ionospheric irregularities over the auroral and polar regions while the high-latitude ionosphere is in partial darkness. TEC is observed entering the polar cap and being broken up into a patch in a region of strong phase scintillation. The second and third storms occur in the deep Antarctic winter and show far less in the way of TEC in the polar cap; nevertheless they show strong evidence of phase scintillation and irregularities observed from multiple instruments across the polar region. The results provide new evidence for the importance of particle precipitation in causing phase scintillation in the polar regions on low-elevation GPS signals. It is anticipated that this will be useful input in forming a realistic statistical model of the irregularities in the high-latitude ionosphere that are responsible for phase and amplitude scintillation on a variety of radio signals.

  11. Ionospheric Features Diagnosed by Radio Tomography during Strong Geomagnetic Disturbances

    NASA Astrophysics Data System (ADS)

    Andreeva, Elena S.; Kunitsyn, Vyacheslav E.; Tereshchenko, Evgeniy D.; Kozharin, Maksim A.; Nazarenko, Marina O.

    2013-04-01

    During the periods of geomagnetic storms, the ionosphere has a particularly complicated and rapidly changing structure. Each storm is marked by its own set of specific manifestations, which reflect rearrangement of the dynamical pattern of the ionosphere and strong perturbations in its parameters. The complexity and global scale of the ionospheric processes that occur during the storms call for the nonlocal methods for diagnosing the spatiotemporal structure of the ionospheric disturbances. Here, we present the results of studying the ionospheric structure by the methods of low orbital radio tomography (RT). The ionospheric radio tomography is rapidly developing during the last two decades. Due to the sufficiently high satellite velocity (~7.9 km/s) and, correspondingly, quite fast (compared to the characteristic times of the ionospheric processes) passage of the satellite through the ionospheric region under study, the radio tomographic approach is suitable for making nearly instantaneous (covering an interval of 5-10 min) 2D snapshots of the ionosphere in the altitude-latitude plane. The vertical and horizontal resolution of RT is 30-40 km and 20-30 km, respectively. We consider the ionospheric manifestations of strong geomagnetic storms (1991-2012) in different regions worldwide including the European part of Russia and North America. We note that during the geomagnetic disturbances, the ionosondes frequently show unstable operation. In contrast to the ionosondes that use HF radio waves, the RT methods are suitable for imaging the ionosphere even during severe solar and geophysical disturbances. During the periods of strong perturbations, RT detected various wavelike structures, travelling ionospheric disturbances, and different manifestations of acoustic gravity waves in the ionosphere. Using the RT methods, the wave effects of particle precipitation were analyzed, and plasma flows were estimated. Radio tomographic imaging of the ionosphere during severe disturbances reveals multiextremal spotty patterns with steep wall-like gradients in electron density in the north. Thin enhancements of electron concentration that are elongated by hundreds of kilometers along the magnetic field lines and attain dozens of kilometers in the transversal direction are identified. The complexly structured ionospheric trough with a tilted polar wall shifted towards the equator is revealed. Many RT reconstructions show the ionospheric trough to split. For example, the RT imaging of the storm of March 24-28, 1991 indicates that the ionospheric structures that are normally typical of the subauroral and auroral ionosphere (the troughs and anomalous ionization in the F-region) reached middle latitudes at that time. During the strongest geomagnetic storm on October 30-31, 2003, the ionosphere over the European part of Russia was marked by anomalously high electron concentration; the distribution of electron density in the region of increased ionization was extremely complicated in space and highly variable in time. We are grateful to the North-West Research Associates (NWRA) for providing the experimental data on relative TEC measured at the RT system in Alaska. The work was supported by the Russian Foundation for Basic Research (grants 11-05-01157 and 13-05-01122).

  12. First observation of the anomalous electric field in the topside ionosphere by ionospheric modification over EISCAT

    NASA Astrophysics Data System (ADS)

    Kosch, M. J.; Vickers, H.; Ogawa, Y.; Senior, A.; Blagoveshchenskaya, N.

    2014-11-01

    We have developed an active ground-based technique to estimate the steady state field-aligned anomalous electric field (E*) in the topside ionosphere, up to ~600 km, using the European Incoherent Scatter (EISCAT) ionospheric modification facility and UHF incoherent scatter radar. When pumping the ionosphere with high-power high-frequency radio waves, the F region electron temperature is significantly raised, increasing the plasma pressure gradient in the topside ionosphere, resulting in ion upflow along the magnetic field line. We estimate E* using a modified ion momentum equation and the Mass Spectrometer Incoherent Scatter model. From an experiment on 23 October 2013, E* points downward with an average amplitude of ~1.6 ?V/m, becoming weaker at higher altitudes. The mechanism for anomalous resistivity is thought to be low-frequency ion acoustic waves generated by the pump-induced flux of suprathermal electrons. These high-energy electrons are produced near the pump wave reflection altitude by plasma resonance and also result in observed artificially induced optical emissions.

  13. Momentum, Heat, and Neutral Mass Transport in Convective Atmospheric Pressure Plasma-Liquid Systems and Implications for Aqueous Targets

    E-print Network

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

    2015-01-01

    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 $\\mu$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 fro...

  14. Theory for induced convection experiments in the tokamak edge

    E-print Network

    Theory for induced convection experiments in the tokamak edge P. Helander1 , D.D. Ryutov2 , and R convection in the edge plasma, leading to an increase of the SOL thickness and a reduction of the heat load. The present paper addresses a range of theory issues connected with such induced plasma convection

  15. Modeling Convection

    NSDL National Science Digital Library

    Amanda Schulz

    2004-09-01

    Typically, teachers use simple models that employ differences in temperature and density to help students visualize convection. However, most of these models are incomplete or merely hint at (instead of model) convective circulation. In order to make the use of models more effective, the authors developed an alternative system that uses a simple, low-cost apparatus that not only maintains dynamic convective circulation, but also illustrates two adjacent cells that teaches students about Earth's processes.

  16. Research on the lunar ionosphere using dual-frequency radio occultation with a small VLBI antenna

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Wang, Na; Ping, Jinsong

    2015-04-01

    The Vstar in the Japanese lunar SELENE Radio Science experiment was occulted by virtue of the lunar ionosphere. Using the single sub-satellite and the S/X band coherent radio waves, dual-frequency measurements were acquired at a ground receiving station. In order to investigate the variation of ionospheric total electron content (TEC) surrounding the moon, the TEC, including the terrestrial ionosphere, the interplanetary plasma and lunar ionosphere, can be derived from the phase information of the observational data. We update the observation equation and algorithms, calculate the linear fitting trend of the lunar ionosphere from 60 to 30 km above the surface of the moon. The fitting trend is extended from 30 to 0 km above the surface of the moon. The lunar ionosphere is obtained by using the short time trend extrapolation method.

  17. Electric fields in the ionosphere

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.

    1975-01-01

    F-region drift velocities, measured by incoherent-scatter radar were analyzed in terms of diurnal, seasonal, magnetic activity, and solar cycle effects. A comprehensive electric field model was developed that includes the effects of the E and F-region dynamos, magnetospheric sources, and ionospheric conductivities, for both the local and conjugate regions. The E-region dynamo dominates during the day but at night the F-region and convection are more important. This model provides much better agreement with observations of the F-region drifts than previous models. Results indicate that larger magnitudes occur at night, and that daily variation is dominated by the diurnal mode. Seasonal variations in conductivities and thermospheric winds indicate a reversal in direction in the early morning during winter from south to northward. On magnetic perturbed days and the drifts deviate rather strongly from the quiet days average, especially around 13 L.T. for the northward and 18 L.T. for the westward component.

  18. Thermodynamic effect of the ion sound instability in the ionosphere

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Gombosi, T. I.; Gorbachev, O. A.; Trukhan, A. A.; Miller, R. H.

    1994-01-01

    During geomagnetic disturbances when the ring current interacts intensely with the plasmasphere, the plasma of this region undergoes a strong heating due to an ion cyclotron instability. This is followed by the transfer of heat along geomagnetic field lines from the heating region to the ionosphere. One of the results of this process is the formation of non-isothermal region (in which T(sub e) greater than 3.4 T(sub i) at ionospheric heights) caused by a rapid cooling the H(+) ions due to their resonant charge exchange with neutral hydrogen. Heat transfer from the top of the flux tube to the ionosphere is investigated using a hydrodynamic model for the ionosphere-plasmasphere coupling. Field-aligned currents, present in the topside ionosphere, are often accompanied by ion sound turbulence. The turbulence scatters electrons, increasing the total electron collision frequency through wave-particle effects. The influence of wave-particle interactions introduces an anomalous component to the total collision frequency, which modifies substantially the heat conduction coefficient of the plasma. As a result, the plasma is heated more intensely above than below this region of ion sound turbulence.

  19. Characterizing Extreme Ionospheric Storms

    NASA Astrophysics Data System (ADS)

    Sparks, L.; Komjathy, A.; Altshuler, E.

    2011-12-01

    Ionospheric storms consist of disturbances of the upper atmosphere that generate regions of enhanced electron density typically lasting several hours. Depending upon the storm magnitude, gradients in electron density can sometimes become large and highly localized. The existence of such localized, dense irregularities is a major source of positioning error for users of the Global Positioning System (GPS). Consequently, satellite-based augmentation systems have been implemented to improve the accuracy and to ensure the integrity of user position estimates derived from GPS measurements. Large-scale irregularities generally do not pose a serious threat to estimate integrity as they can be readily detected by such systems. Of greater concern, however, are highly localized irregularities that interfere with the propagation of a signal detected by a user measurement but are poorly sampled by the receivers in the system network. The most challenging conditions have been found to arise following disturbances of large magnitude that occur only rarely over the course of a solar cycle. These extremely disturbed conditions exhibit behavior distinct from moderately disturbed conditions and, hence, have been designated "extreme storms". In this paper we examine and compare the behavior of the extreme ionospheric storms of solar cycle 23 (or, more precisely, extreme storms occurring between January 1, 2000, and December 31, 2008), as represented in maps of vertical total electron content. To identify these storms, we present a robust means of quantifying the regional magnitude of an ionospheric storm. Ionospheric storms are observed frequently to occur in conjunction with magnetic storms, i.e., periods of geophysical activity as measured by magnetometers. While various geomagnetic indices, such as the disturbance storm time (Dst) and the planetary Kp index, have long been used to rank the magnitudes of distinct magnetic storms, no comparable, generally recognized index exists for measuring ionospheric storm magnitudes. Since the level of ionospheric disturbance (as represented, for example, by enhancements or depletions in total electron content) does not always scale directly with the level of geophysical disturbance in a coincident magnetic storm, however, an independent, purely ionospheric storm index is preferable for ranking ionospheric storms by their magnitudes. Our storm magnitude metric is calculated from the standard ?2 goodness-of-fit parameter values associated with estimates of vertical total electron content (derived from observations collected by networks of GPS receivers) on a grid at regularly spaced intervals of geodetic latitude and longitude. It takes into account both the instantaneous magnitude of the storm and its temporal duration.

  20. Simulation of ion outflows in the ionosphere

    NASA Astrophysics Data System (ADS)

    Sydorenko, D.; Rankin, R.

    2012-12-01

    Ion outflows are observed in the polar region in response to particle precipitation and magnetospheric wave activity. In order to study the ion outflow, we modified the previously developed two-dimensional model of realistic active ionosphere [Sydorenko, 2012] by including ion motion along the geomagnetic field. The new model considers a layer of near-Earth plasma of thickness of a few thousand kilometers. The plasma consists of multiple ion species. Collisions between particles are accounted for everywhere, even at high altitudes where they are negligible. Therefore, unlike in the previous model, the electron and ion dynamics is continuous. Chemical reactions between different ion and neutral species are included. Simulations demonstrate formation of field-aligned ion flows when an intense Alfven wave or electron precipitation perturbs the ionosphere. The significance of the results is discussed in the context of Canadian Space Agency e-POP spacecraft mission. Sydorenko D. and R. Rankin, "Simulation of ionospheric disturbances created by Alfven waves", submitted to Journal of Geophysical Research, 2012.

  1. Generation of large-scale gravity waves and neutral winds in the thermosphere from the dissipation of convectively

    E-print Network

    Vadas, Sharon

    and generates large-scale secondary GWs and large-scale traveling ionospheric disturbances (LSTIDs causes periodic advection and compression of the plasma called traveling ionospheric disturbances (TIDs June 2009; published 21 October 2009. [1] We study the response of the thermosphere and ionosphere

  2. Ionosphere Waves Service - A demonstration

    NASA Astrophysics Data System (ADS)

    Crespon, François

    2013-04-01

    In the frame of the FP7 POPDAT project the Ionosphere Waves Service was developed by ionosphere experts to answer several questions: How make the old ionosphere missions more valuable? How provide scientific community with a new insight on wave processes that take place in the ionosphere? The answer is a unique data mining service accessing a collection of topical catalogues that characterize a huge number of Atmospheric Gravity Waves, Travelling Ionosphere Disturbances and Whistlers events. The Ionosphere Waves Service regroups databases of specific events extracted by experts from a ten of ionosphere missions which end users can access by applying specific searches and by using statistical analysis modules for their domain of interest. The scientific applications covered by the IWS are relative to earthquake precursors, ionosphere climatology, geomagnetic storms, troposphere-ionosphere energy transfer, and trans-ionosphere link perturbations. In this presentation we propose to detail the service design, the hardware and software architecture, and the service functions. The service interface and capabilities will be the focus of a demonstration in order to help potential end-users for their first access to the Ionosphere Waves Service portal. This work is made with the support of FP7 grant # 263240.

  3. Modeling of ionospheric scintillation at low-latitude

    NASA Astrophysics Data System (ADS)

    Patel, K.; Singh, Ashutosh K.; Subrahmanyam, P.; Singh, A. K.

    2011-02-01

    The presence and movement of plasma density fluctuations in the F-region of the ionosphere are studied by monitoring phase and amplitude of radio waves propagating through the region. In this paper, we have used weak scattering theory and assumed the plasma density fluctuations to behave like phase changing diffraction screen. Appropriate relations for scintillation index S4, and phase variance ?? are derived and computed for different parameters of the plasma density irregularities of the ionosphere. SROSS-C2 satellite in situ measurements of plasma density fluctuations, which provide direct information about the structure and morphology of irregularities that are responsible for scintillation of radio waves, were used first time to develop a scintillation model for low latitude. It is observed that the scintillation index S4 and phase variance ?? depends on the strength of the plasma turbulence. Finally, the results obtained from modeling are compared and discussed with the available recent results.

  4. Drift wave instability in the Io plasma torus

    NASA Technical Reports Server (NTRS)

    Huang, T. S.; Hill, T. W.

    1991-01-01

    A linear normal mode analysis of the drift wave instability in the Io plasma torus was carried out on the basis of the Richmond (1973) and Huang et al. (1990) analyses of drift waves in the vicinity of the earth's plasmapause. Results indicate that the outer torus boundary is linearly unstable to the growth of electrostatic drift waves. It is shown that the linear growth rate is proportional to the ion drift frequency and to the ratio of the flux tube charge content to the Jovian ionospheric Pedersen conductance. It is also shown that various theoretical models of global radial transport in Jupiter's atmosphere (including corotating convection, interchange diffusion, and transient flux tube convection) can be understood as plausible nonlinear evolutions of electrostatic drift waves.

  5. Interball project - some cause-and-effect relationships for investigated magnetosphere-ionosphere processes, clarified by uvsips, ska-3, imap-3 experiments on board the interball-2

    NASA Astrophysics Data System (ADS)

    Palazov, K.; Bochev, A.; Manev, A.; Getsov, P.; Jekov, J.; Jekov, S.; Mardirosyan, G.; Kusmin; Esmont, N.; Prokhorenko, V.

    The instruments Magnetometer IMAP-- 3 (STIL-Bulgaria) and SKA-3 (a set of particle detectors - RAN- Russia), operating onboard the Interball -- 2 satellite provide in - situ characteristics of the magnetic field, the distribution functions of the electrons and ions, respectively. The UV spectrometer UVSIPS by remote sensing maps ionospheric auroral characteristics in the magnetic field line foot print in 3 lines: of the atomic oxygen (1304 A, 1356 A) and of the nitrogen (1493 A), thus providing monitoring of the interaction solar wind-magnetosphere-ionosphere. We present co-related results from those experiments, confirming some cause-and-effect physical relationships: solar wind/magnetosheet plasma characteristics, their interactions with the outer regions of the magnetosphere, the active plasma processes, the substorm-type phenomena, the magnetosphere-ionosphere interactions, the plasma convection, the auroral phenomena, the respective auroral and airglow manifestations, etc. The obtained results, such as the relation of the UV line intensity I1304/I1356, the frontiers of the auroral oval, the height and dimensions of the auroral arcs, the space and time relationship between the solar wind and the aurora, the measurements of dayside aurora (the substorm usually starts at the equatorward arc of the oval) and others are presented. In addition, our investigation provokes questions about some phenomena as a challenge for future exploration and theoretical explanations - for example, the phenomenon found at the polar edge of the auroral oval in the postmidnight - morning sectors: field-aligned (FA) high-energy upward electron beams in the energy range 20 - 45 keV at altitudes about 3 RE, accompanied by bi-directional electron FA beams of keV energy. Our partial results show the necessity to proceed with the next stage of complete data processing of all experiments in the project in order to make a good evaluation of the investigated phenomena and to achieve the main aims of Interball project.

  6. Topside sounders as mobile ionospheric heaters

    NASA Technical Reports Server (NTRS)

    Benson, R. F.

    2006-01-01

    There is evidence that satellite-borne RF sounders can act as mobile ionospheric heaters in addition to performing topside sounding. The main objective of topside sounding is to use sounder-generated electromagnetic (em) waves to obtain ionospheric topside vertical electron-density (N(sub e) profiles. These profiles are obtained from mathematical inversions of the frequency vs. delay-time ionospheric reflection traces. In addition to these em reflection traces, a number of narrowband intense signals are observed starting at zero delay times after the transmitted pulses. Some of these signals, termed plasma resonances, appear at characteristic frequencies of the ambient medium such as at the electron cyclotron frequency f(sub ce), the harmonics nf(sub ce), the electron plasma frequency f(sub pe) and the upper-hybrid frequency f(sub uh), where (f(sub uh))(exp 2) = (f(sub ce))(exp 2) + (f(sub pe))(exp 2) . These signals have been attributed to the oblique echoes of sounder-generated electrostatic (es) waves. These resonances provide accurate in situ f(sub pe) and f(sub ce) values which, in turn, lead to accurate N(sub e) and [B] values where B is the ambient magnetic field. Resonances are also observed between the nf(sub ce) harmonics both above and below f(sub uh). The former, known as the Qn plasma resonances, are mainly attributed to the matching of the wave group velocity of sounder-generated (Bernstein-mode) es waves to the satellite velocity. The frequency spectrum of these waves in the magnetosphere can be used to detect non-Maxwellian electron velocity-distributions. In addition, these resonances also exhibit components that appear to be the result of plasma emissions stimulated by the sounder pulses. The plasma resonances observed between the nf(sub ce) harmonics and below f(sub uh), known as the Dn plasma resonances, are entirely attributed to such sounder-stimulated plasma emissions. There are other sounder-stimulated plasma phenomena that also fall into this category, e.g., ion affects on electron-resonant phenomena, proton-cyclotron echoes and N(sub e) field-aligned irregularities (FAI). Some of these phenomena are more pronounced when f(sub pe)/f(sub ce) approx. = n where n is an integer significantly greater than one. The observations suggest that the sounder-stimulated plasma phenomena are stimulated, or enhanced, on a time scale much less than one second. The purpose of this presentation is to review the above topics with particular emphasis on the sounder-stimulated plasma phenomena.

  7. Solitons and ionospheric heating

    NASA Technical Reports Server (NTRS)

    Weatherall, J. C.; Goldman, M. V.; Sheerin, J. P.; Nicholson, D. R.; Payne, G. L.; Hansen, P. J.

    1982-01-01

    It is noted that for parameters characterizing the Platteville ionospheric heating facility, the Langmuir wave evolution at the exact reflection point of the heater wave involves an oscillating two-stream instability followed by a collisionally damped three-dimensional soliton collapse. The result gives an alternative explanation for certain experimental observations.

  8. Gas convection caused by electron pressure drop in the afterglow of a pulsed inductively coupled plasma discharge

    SciTech Connect

    Cunge, G.; Vempaire, D.; Sadeghi, N. [Laboratoire des Technologies de la Microelectronique, CEA-LETI, CNRS, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2010-03-29

    Neutral depletion is an important phenomenon in high-density plasmas. We show that in pulsed discharges, the neutral depletion caused by the electron pressure P{sub e} plays an important role on radical transport. In the afterglow, P{sub e} drops rapidly by electron cooling. So, a neutral pressure gradient built up between the plasma bulk and the reactor walls, which forces the cold surrounding gas to move rapidly toward the reactor center. Measured drift velocity of Al atoms in the early afterglow of Cl{sub 2}/Ar discharge by time-resolved laser induced fluorescence is as high as 250 ms{sup -1}. This is accompanied by a rapid gas cooling.

  9. Broadband meter-wavelength observations of ionospheric scintillation

    NASA Astrophysics Data System (ADS)

    Fallows, R. A.; Coles, W. A.; McKay-Bukowski, D.; Vierinen, J.; Virtanen, I. I.; Postila, M.; Ulich, Th.; Enell, C.-F.; Kero, A.; Iinatti, T.; Lehtinen, M.; Orispää, M.; Raita, T.; Roininen, L.; Turunen, E.; Brentjens, M.; Ebbendorf, N.; Gerbers, M.; Grit, T.; Gruppen, P.; Meulman, H.; Norden, M. J.; de Reijer, J.-P.; Schoenmakers, A.; Stuurwold, K.

    2014-12-01

    Intensity scintillations of cosmic radio sources are used to study astrophysical plasmas like the ionosphere, the solar wind, and the interstellar medium. Normally, these observations are relatively narrow band. With Low-Frequency Array (LOFAR) technology at the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA) station in northern Finland we have observed scintillations over a three-octave bandwidth. "Parabolic arcs," which were discovered in interstellar scintillations of pulsars, can provide precise estimates of the distance and velocity of the scattering plasma. Here we report the first observations of such arcs in the ionosphere and the first broadband observations of arcs anywhere, raising hopes that study of the phenomenon may similarly improve the analysis of ionospheric scintillations. These observations were made of the strong natural radio source Cygnus-A and covered the entire 30-250 MHz band of KAIRA. Well-defined parabolic arcs were seen early in the observations, before transit, and disappeared after transit although scintillations continued to be obvious during the entire observation. We show that this can be attributed to the structure of Cygnus-A. Initial results from modeling these scintillation arcs are consistent with simultaneous ionospheric soundings taken with other instruments and indicate that scattering is most likely to be associated more with the topside ionosphere than the F region peak altitude. Further modeling and possible extension to interferometric observations, using international LOFAR stations, are discussed.

  10. Ionospheric mid-latitude response to solar wind discontinuities

    NASA Astrophysics Data System (ADS)

    Munteanu, Costel; Mosna, Zbysek; Kouba, Daniel; Echim, Marius

    2013-04-01

    We have compiled a database of 356 discontinuities detected by both the Advanced Composition Explorer ACE) and Cluster satellites in the solar wind between 2001-2012 and analyzed their ionospheric response. Each discontinuity of the data base is defined by a change of at least 5 nT in less than 5 min in one or more components of the interplanetary magnetic field (IMF). The discontinuities are observed in January-April every year, when Cluster enters the solar wind. The ionospheric effects of solar wind discontinuities are investigated by checking the variations of critical frequencies foF2, the heights of the F layer and the ionospheric plasma dynamics recorded using ground measurement with a time resolution of 15 minutes from mid-latitude digisondes located in Czech Republic. The time delay between solar wind input and the ionospheric response is analyzed using the characteristics and the shape of the ionograms. The geoeffectiveness of the solar wind discontinuities is expressed as correlation between key plasma parameters (e,g, the solar wind velocity, magnetic jump across the discontinuity) and the ionospheric variations. Solar cycle effects are also discussed.

  11. Transport of ionospheric ions in the magnetosphere - Theory and observations

    NASA Astrophysics Data System (ADS)

    Cladis, J. B.

    The distribution functions of upward flowing ions from a source location in the ionosphere into the magnetosphere were investigated using a Monte Carlo transport code described by Gladis and Francis (1985). The characteristics of the ions in the lobes, the plasma sheet, and the storm-time ring current, as determined with this code, are compared with ion measurements in these regions.

  12. Viscous Forces in Velocity Boundary Layers around Planetary Ionospheres.

    PubMed

    Pérez-De-Tejada

    1999-11-01

    A discussion is presented to examine the role of viscous forces in the transport of solar wind momentum to the ionospheric plasma of weakly magnetized planets (Venus and Mars). Observational data are used to make a comparison of the Reynolds and Maxwell stresses that are operative in the interaction of the solar wind with local plasma (planetary ionospheres). Measurements show the presence of a velocity boundary layer formed around the flanks of the ionosphere where the shocked solar wind has reached super-Alfvénic speeds. It is found that the Reynolds stresses in the solar wind at that region can be larger than the Maxwell stresses and thus are necessary in the local acceleration of the ionospheric plasma. From an order-of-magnitude calculation of the Reynolds stresses, it is possible to derive values of the kinematic viscosity and the Reynolds number that are suitable to the gyrotropic motion of the solar wind particles across the boundary layer. The value of the kinematic viscosity is comparable to those inferred from studies of the transport of solar wind momentum to the earth's magnetosphere and thus suggest a common property of the solar wind around planetary obstacles. Similar conditions could also be applicable to velocity boundary layers formed in other plasma interaction problems in astrophysics. PMID:10511515

  13. High-latitude ionospheric electrodynamics as determined by the assimilative mapping of ionospheric electrodynamics procedure for the conjunctive SUNDIAL\\/ATLAS 1\\/GEM period of March 28–29, 1992

    Microsoft Academic Search

    G. Lu; B. A. Emery; A. S. Rodger; M. Lester; J. R. Taylor; D. S. Evans; J. M. Ruohoniemi; W. F. Denig; O. de la Beaujardière; R. A. Frahm; J. D. Winningham; D. L. Chenette

    1996-01-01

    During the conjunctive SUNDIAL\\/ATLAS 1\\/GEM campaign period of March 28-29, 1992, a set of comprehensive data has been collected both from space and from ground. The assimilative mapping of ionospheric electrodynamics (AMIE) procedure is used to derive the large-scale high-latitude ionospheric conductivity, convection, and other related quantities, by combining the various data sets. The period was characterized by several moderate

  14. High-latitude ionospheric electrodynamics as determined by the assimilative mapping of ionospheric electrodynamics procedure for the conjunctive SUNDIAL\\/ATLAS 1\\/GEM period of March 28-29, 1992

    Microsoft Academic Search

    G. Lu; B. A. Emery; A. S. Rodger; M. Lester; J. R. Taylor; D. S. Evans; J. M. Ruohoniemi; W. F. Denig; O. de la Beaujardière; R. A. Frahm; J. D. Winningham; D. L. Chenette

    1996-01-01

    During the conjunctive SUNDIAL\\/ATLAS 1\\/GEM campaign period of March 28-29, 1992, a set of comprehensive data has been collected both from space and from ground. The assimilative mapping of ionospheric electrodynamics (AMIE) procedure is used to derive the large-scale high-latitude ionospheric conductivity, convection, and other related quantities, by combining the various data sets. The period was characterized by several moderate

  15. Magnetospheres of Planets and Moons: Links to Their Ionospheres. (Invited)

    NASA Astrophysics Data System (ADS)

    Kivelson, M. G.

    2010-12-01

    The phrase “magnetosphere-ionosphere coupling” has become almost hackneyed in the terrestrial context, but plays an important role in the terrestrial system and must also be emphasized in the context of planetary- and moon-magnetospheres because the underlying principles are similar in all systems. This talk will introduce only two intriguing aspects of the coupling problem for planets and moons. In describing the first topic, we note that, especially for the gas giants Jupiter and Saturn, much of the evidence of magnetosphere-ionosphere coupling is obtained from auroral imaging. In images of Jupiter’s polar ionosphere, bright auroral spots are found to link magnetically to the moons Io, Europa and Ganymede. The spots give evidence of intense field-aligned currents generated near the equator in the interaction between the moons and the flowing plasma of Jupiter’s magnetosphere. The currents must penetrate through regions of impedance mismatch near the upper and lower boundaries of Jupiter’s equatorial plasma torus in order to close in the planetary ionosphere. There is some evidence that the signal propagates through the strong gradient of plasma density at the boundary of the plasma torus by converting into a striated structure that guides high frequency waves. As well, at Io, the interaction has been found to generate localized intense electron fluxes observed to flow along and antiparallel to the magnetic field near the equator. These bidirectional beams are probably accelerated by parallel electric fields near the ionospheric ends of the flux tube, but how the accelerated electrons reach the equator has not been explained. It seems likely that their presence there requires that the (parallel) electric fields in the Jovian ionosphere vary either temporally at high frequency or spatially on short transverse length scales. The full explanation has not yet been developed. As a second example of the role of magnetosphere-ionosphere coupling in planetary systems, we turn to an MHD simulation of the mini-magnetosphere of Ganymede carried out by X. Jia (2010). The significance of the ionosphere in the simulation is that, as the inner plasma boundary, it affects the flow and the dynamics of the entire system. The mathematical reason for the result is evident: differential equations have different solutions for different boundary conditions, but the dramatic changes that arise throughout the entire volume of the magnetosphere as the inner boundary condition is slightly modified may be both surprising and illuminating.

  16. A plasma flow velocity boundary at Mars from the disappearance of electron plasma oscillations

    E-print Network

    Gurnett, Donald A.

    echo due to vertical reflection from the horizontally stratified ionosphere is measured (Gurnett et al sounding mode, the sounder transmitter excites electrostatic electron plasma oscillations at the local

  17. Chemistry in the Thermosphere and Ionosphere.

    ERIC Educational Resources Information Center

    Roble, Raymond G.

    1986-01-01

    An informative review which summarizes information about chemical reactions in the thermosphere and ionosphere. Topics include thermal structure, ultraviolet radiation, ionospheric photochemistry, thermospheric photochemistry, chemical heating, thermospheric circulation, auroral processes and ionospheric interactions. Provides suggested followup…

  18. Study of the ionospheric variability within the Euro-Asian sector during the Sundial/Atlas 1 mission

    NASA Astrophysics Data System (ADS)

    Pulinets, S. A.; Yudakhin, K. F.; Evans, D.; Lester, M.

    1996-12-01

    In order to quantify, and to identify possible origins of, subauroral ionospheric variability during periods of moderate geomagnetic activity, ionospheric observations taken during the SUNDIAL/ATLAS-1 campaign (March 24 to April 2) from 10 stations were analyzed in conjunction with observations from EISCAT, geomagnetic observations from magnetometer networks in Scandinavia and the United Kingdom, and auroral particle energy input observations from the NOAA-12 satellite. The network of ionospheric stations spanned longitudes from 13°E to 90°E but were relatively confined in geomagnetic latitudes so that longitudinal and local time dependencies in ionospheric variability are more clearly exposed. The ionospheric observations were analyzed in terms of both ?f0F2, the difference between the hourly f0F2 at a given station and the monthly median f0F2 for that hour, and a new daily variability index Af0F2. The analysis using both parameters demonstrated an apparent longitudinal variation in ionospheric variability with a reversal at about 55°E from a negative to a positive phase in the departure of ionospheric conditions from their median values. An analysis of these ionospheric data in conjunction with the NOAA/TIROS estimates of power deposition by auroral particles demonstrated a significant local time dependence in midlatitude ionospheric responses to auroral activity. This dependence may arise from the premidnight to postmidnight asymmetry in high-latitude convection electric fields.

  19. Stimulated Emissions and Radar Scatter from Pulsed RF-Ionosphere Interactions at HAARP

    Microsoft Academic Search

    J. P. Sheerin; J. P. Mills; K. M. Groves; W. A. Bristow; Jacqueline Pau; A. Y. Wong

    2001-01-01

    High power HF radiowave pulses launched from ground-based transmitters interact with overdense quiescent ionospheric plasma to produce strong turbulence effects. These effects are evident in the ion and plasma lines detected by diagnostic radars. Several spatial and temporal signatures in the backscattered plasma lines show reproducible evidence of strong turbulence effects at many scales. Complementary to radar probe diagnostics are

  20. Stimulated Emission and Radar Observations of RF-Ionosphere Interaction Experiments at HAARP

    Microsoft Academic Search

    J. P. Sheerin; J. M. Parzych; J. P. Mills; W. A. Bristow; K. M. Groves

    2003-01-01

    High power HF radiowaves launched from ground-based transmitters interact with overdense ionospheric plasma to produce strong nonlinear effects. Where available, VHF\\/UHF radar data reveal several spatial and temporal signatures in the plasma line backscatter indicative of strong turbulence effects at many scales. Stimulated electromagnetic emissions (SEE) which propagate to HF receivers on the ground may provide information complementary to plasma

  1. Convection Movies

    NSDL National Science Digital Library

    Stephane Labrosse

    This page, on the website of Stephane Labrosse of ENS Lyon, presents some examples of flow motions resulting from convection calculations in different situations. All are for infinite Prandtl number and free-slip boundary conditions on horizontal surfaces

  2. Understanding Ionospheric Connections to Sun and Earth

    NASA Astrophysics Data System (ADS)

    Immel, Thomas J.; Rowland, Doug; England, Scott; Talaat, Elsayed; Jones, Sarah

    2015-04-01

    Earth's ionosphere is the dense plasma environment that dominates the boundary between our atmosphere and space. In contrast with long-standing understanding of the ionosphere as a phenomenon influenced by changes in solar radiation and solar wind, observations over the past decade have shown us that its large day-to-day variability likely originates with forcing from the lower atmosphere. This realization came with a combination of key observations utilizing pioneering measurement techniques, the emergence of sophisticated whole-atmosphere modeling approaches, and the development and application of innovative analysis techniques. The large and unexpected signatures in the ionosphere drove real ingenuity in the development of modeling and analysis techniques, in part for the lack of needed measurements of key aspects of Earth's space environment. Still, the causal links are incomplete and a significant effort is now being mounted to make these necessary measurements and build a more complete view of the coupled space-atmosphere system. Here we will review these efforts, including the upcoming NASA missions ICON and GOLD, and discuss recent results that offer further promise for future ground-breaking observations and discovery.

  3. RCM-E and AMIE studies of the Harang reversal formation during a steady magnetospheric convection event

    NASA Astrophysics Data System (ADS)

    Yang, Jian; Toffoletto, Frank; Lu, Gang; Wiltberger, Michael

    2014-09-01

    This paper presents the results of a modeling study on the formation of the Harang reversal (HR) during a steady magnetospheric convection event. The Harang reversal is identified as the boundary of the northward and southward electric field in the nightside auroral zone using the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure. We simulate the event with the Rice Convection Model-Equilibrium (RCM-E) by adjusting its boundary conditions to approximately match Time History of Events and Macroscale Interactions during Substorms (THEMIS) and GOES observations in the nightside magnetosphere. Our results show that the HR is collocated with an upward region 1 field-aligned current, where converging ionospheric currents cause a southward/northward electric field on the poleward/equatorward side of the HR. Our results also indicate that the electric field reversal is slightly poleward of the ionospheric east-west current reversal and is to the northeast of the ground magnetic reversal, which is consistent with previous observations. We also test the sensitivity of the HR formation to a variety of parameters in the RCM-E simulations. We find that (1) the reduction of the flux tube entropy parameter PV5/3 near the midnight sector plays a major role in the formation of the HR; (2) a run carried out assuming uniform conductance produced the same major features as the run with more realistic precipitation-enhanced conductance; and (3) the detailed pattern of the polar cap potential distribution plays a minor role, but its dawn-dusk asymmetry significantly controls the location of the HR with respect to midnight. The RCM-E simulations also predict PV5/3 and flow distributions associated with the magnetospheric source of the HR in the plasma sheet, which can be further tested against observations.

  4. Theory of radar detection of solitons during ionospheric heating

    NASA Technical Reports Server (NTRS)

    Sheerin, J. P.; Nicholson, D. R.

    1983-01-01

    RF modifiers at some existing ionospheric-heating facilities are found to be sufficiently intense for the production of (collapsing) solitons. The detection of these solitons using Thomson radar is considered, and the problem of an electromagnetic wave scattering off a collection of collapsing solitons is treated. The cross section for the process is found to be relatively large, and an intense plasma-line backscatter is predicted. An explanation of the phenomenon of 'plasma-line overshoot' is suggested.

  5. Ionospheric Irregularities at High Latitudes During Geomagnetic Storms and Substorms: Simultaneous Observations of Magnetic Field Perturbations and GPS Scintillations

    NASA Astrophysics Data System (ADS)

    Kim, H.; Deshpande, K.; Clauer, C. R.; Bust, G. S.; Crowley, G.; Humphreys, T. E.; Kim, L.; Lessard, M.; Weatherwax, A. T.; Zachariah, T. P.

    2012-12-01

    Plasma instability in the ionosphere is often observed as disturbance and distortion of the amplitude and phase of radio signals, which are known as ionospheric scintillations. High-latitude ionospheric plasma, closely connected to solar wind and magnetospheric dynamics, produce very dynamic and short-lived GPS scintillations, making it challenging to characterize them. This study reports simultaneous observations of geomagnetic pulsations and GPS signal scintillations during geomagnetic storms and substorms using a newly designed Autonomous Adaptive Low-Power Instrument Platform (AAL-PIP) installed at the South Pole. A statistical investigation of the AAL-PIP data recorded from January through May 2012 is presented to study local time distribution of scintillation events and a correlation between GPS scintillation and magnetic field perturbations. This report discusses a possible connection between magnetic field perturbations associated with the ionospheric currents and the creation of plasma instability by examining relative contribution of storm/substorm activity to ionospheric irregularities.

  6. Magnetosphere-ionosphere coupling

    Microsoft Academic Search

    C. K. Goertz; R. W. Boswell

    1979-01-01

    A simple two-dimensional model of the magnetosphere-ionosphere system is discussed in which a localized electromotive force applied across a magnetic field line at t=0 is shown to propagate along the magnetic field with the Alfven velocity. The perpendicular electric field is assumed to reverse direction across the field line. Since the perpendicular electric field is limited in space, the propagation

  7. GPS and ionospheric scintillations

    NASA Astrophysics Data System (ADS)

    Kintner, P. M.; Ledvina, B. M.; de Paula, E. R.

    2007-09-01

    Ionospheric scintillations are one of the earliest known effects of space weather. Caused by ionization density irregularities, scintillating signals change phase unexpectedly and vary rapidly in amplitude. GPS signals are vulnerable to ionospheric irregularities and scintillate with amplitude variations exceeding 20 dB. GPS is a weak signal system and scintillations can interrupt or degrade GPS receiver operation. For individual signals, interruption is caused by fading of the in-phase and quadrature signals, making the determination of phase by a tracking loop impossible. Degradation occurs when phase scintillations introduce ranging errors or when loss of tracking and failure to acquire signals increases the dilution of precision. GPS scintillations occur most often near the magnetic equator during solar maximum, but they can occur anywhere on Earth during any phase of the solar cycle. In this article we review the subject of GPS and ionospheric scintillations for scientists interested in space weather and engineers interested in the impact of scintillations on GPS receiver design and use.

  8. Electron and ion temperature data for ionospheric modelling

    NASA Technical Reports Server (NTRS)

    Bilitza, Dieter

    1991-01-01

    The major sources ionospheric temperature data are the incoherent scatter radars and in situ instruments (Langmuir probe, retarding potential analyzer) flown on several long-lasting satellite missions. The paper provides an overview over the different data sets and discusses their volume, temporal and spatial resolution, accuracy, and their availability. The state-of-the-art of empirical modeling of ionospheric plasma temperatures is examined, and present shortcomings and future data needs are pointed out. Special emphasis is given to the representation of auroral features, temperature anisotropies, and of solar-cycle variations. Finally, the possibility of using theoretical results to fill data gaps for empirical modeling is considered.

  9. Ionospheric Response to the Acoustic Gravity Wave Singularity

    NASA Astrophysics Data System (ADS)

    Savina, Olga N.; Bespalov, Peter A.

    2015-02-01

    An original model of atmospheric wave propagation from ground sources to the ionosphere in the atmosphere with a realistic high-altitude temperature profile is analyzed. Shaping of a narrow domain with elevated pressure in the resonance region where the horizontal phase wave velocity is equal to the sound velocity is examined theoretically within the framework of linearized Eq.s. Numerical simulations for the model profiles of atmospheric temperature and viscosity confirm analytical result for the special feature of wave fields. The formation of the narrow domain with plasma irregularities in the D and low E ionospheric layers caused by the acoustic gravity wave singularity is discussed

  10. Ionospheric response to the acoustic gravity wave singularity

    NASA Astrophysics Data System (ADS)

    Savina, Olga N.; Bespalov, Peter A.

    2014-11-01

    An original model of atmospheric wave propagation from ground sources to the ionosphere in the atmosphere with a realistic high-altitude temperature profile is analyzed. Shaping of a narrow domain with elevated pressure in the resonance region where the horizontal phase wave velocity is equal to the sound velocity is examined theoretically within the framework of linearized Eq.s. Numerical simulations for the model profiles of atmospheric temperature and viscosity confirm analytical result for the special feature of wave fields. The formation of the narrow domain with plasma irregularities in the D and low E ionospheric layers caused by the acoustic gravity wave singularity is discussed.

  11. Natural hazards monitoring and forecast using the GNSS and other technologies of the ionosphere monitoring

    NASA Astrophysics Data System (ADS)

    Pulinets, S. A.; Davidenko, D.

    2013-12-01

    It is well established now that Atmosphere-Ionosphere Coupling is provided through the local changes of the Global Electric Circuit parameters. Main agent - is column conductivity, modulated mainly at the altitudes of the Global Boundary Layer. We demonstrate the ionospheric effects for different types of natural hazards including volcano eruptions, dusty storms from Western Africa, ionospheric effects from tropical hurricanes, multiple earthquakes. We consider the important role of air ionization from natural (natural ground radioactivity and galactic cosmic rays) and artificial sources (nuclear weapon tests in atmosphere and underground, nuclear power stations and other nuclear enterprises emergencies). We rise also important question that such effects of the ionosphere variability are not taken into account by any ionospheric model and their correct recognition is important not only from the point of view the disasters monitoring but for navigation itself because the magnitude of the ionospheric effects sometimes exceeds the effects from strong magnetic storms and other severe space weather conditions. Some effects like ionospheric effects from tropical hurricanes have more complex physical nature including the formation of streams of neutral atmosphere over the hurricane eye and formation of the strong positive plasma concentration anomaly at the altitude near 1000 km. Some plasma anomalies registered over the tropical depressions before hurricane formation give hope on predictive capabilities of plasma observations over the tropical depressions.

  12. Diagnostics of the ionospheric turbulence by wide band radio signals

    NASA Astrophysics Data System (ADS)

    Sergeev, Evgeny; Shindin, Alexey; Grach, Savely

    Results of the investigations of the time-space structure of the HF-pumped ionospheric volume above the SURA heating facility are presented. The method of investigations is based on mea-surements of the amplitude and phase of pulsed (pulse duration < 200µs and interpulse period 20-200 ms), wide band (˜ 300 kHz) and powerful (Effective Radiated Power ˜ 20-150 MW) radio signals radiated by three SURA transmitter and used for multifrequency sounding of the ionospheric plasma in frequency band up to ˜ 1 MHz. For simultaneous modification of the ionosphere and its diagnostics, technical capabilities of SURA transmitter-receiver system, specially elaborated time-frequency modes of transmitter operation, space diversity three point reception, wide band signal recording, digital filtering, spectral and correlation analysis of the short radio pulses reflected from ionosphere were used. As a result of numerically solved in-verse problem of vertical sounding of the HF-perturbed ionosphere, dynamic behavior of the electron plasma density variations was obtained in the regions close to plasma resonance and upper hybrid resonance of the pump wave. In our experiments the pumping usually leaded to plasma expulsion from the resonance regions. A magnitude of artificial plasma density pertur-bations achieved 0.8% from the background density for pump power about P 60 MW ERP. The methods of a similarity and full correlation analysis were used for pulse signal amplitude processing, which were obtained by diversity three point reception with the receiving aerial separation of 84 m. As a result, novel data on fine structure of the space field of the vertical and horizontal velocities of plasma in the perturbed ionosphere volume with high time (up to 20 ms) and frequency (˜ 1 kHz) resolution are obtained. This frequency resolution can be translated into altitude resolution (˜ 50-100 m) in the ionosphere. The work was supported by RFBR grants 10-02-00642, 09-02-01150 and Federal Special-purpose Program "Scientific and pedagogical personnel of innovative Russia".

  13. Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

    NASA Technical Reports Server (NTRS)

    Bernhardt, P. A.; Ballenthin, J. O.; Baumgardner, J. L.; Bhatt, A.; Boyd, I. D.; Burt, J. M.; Caton, R. G.; Coster, A.; Erickson, P. J.; Huba, J. D.; Earle, G. D.; Kaplan, C. R.; Foster, J. C.; Groves, K. M.; Haaser, R. A.; Heelis, R. A.; Hunton, D. E.; Hysell, D. L.; Klenzing, J. H.; Larsen, M. F.; Lind, F. D.; Pedersen, T. R.; Pfaff, R. F.; Stoneback, R. A.; Roddy, P. A.; Rodriguez, S. P.; San Antonio, G. S.; Schuck, P. W.; Siefring, C. L.; Selcher, C. A.; Smith, S. M.; Talaat, E. R.; Thomason, J. F.; Tsunoda, R. T.; Varney, R. H.

    2013-01-01

    On-orbit firings of both liquid and solid rocket motors provide localized disturbances to the plasma in the upper atmosphere. Large amounts of energy are deposited to ionosphere in the form of expanding exhaust vapors which change the composition and flow velocity. Charge exchange between the neutral exhaust molecules and the background ions (mainly O+) yields energetic ion beams. The rapidly moving pickup ions excite plasma instabilities and yield optical emissions after dissociative recombination with ambient electrons. Line-of-sight techniques for remote measurements rocket burn effects include direct observation of plume optical emissions with ground and satellite cameras, and plume scatter with UHF and higher frequency radars. Long range detection with HF radars is possible if the burns occur in the dense part of the ionosphere. The exhaust vapors initiate plasma turbulence in the ionosphere that can scatter HF radar waves launched from ground transmitters. Solid rocket motors provide particulates that become charged in the ionosphere and may excite dusty plasma instabilities. Hypersonic exhaust flow impacting the ionospheric plasma launches a low-frequency, electromagnetic pulse that is detectable using satellites with electric field booms. If the exhaust cloud itself passes over a satellite, in situ detectors measure increased ion-acoustic wave turbulence, enhanced neutral and plasma densities, elevated ion temperatures, and magnetic field perturbations. All of these techniques can be used for long range observations of plumes in the ionosphere. To demonstrate such long range measurements, several experiments were conducted by the Naval Research Laboratory including the Charged Aerosol Release Experiment, the Shuttle Ionospheric Modification with Pulsed Localized Exhaust experiments, and the Shuttle Exhaust Ionospheric Turbulence Experiments.

  14. Thermal plasma in outer planet magnetospheres

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.; Mcnutt, R. L., Jr.; Richardson, J. D.

    1990-01-01

    The plasma environments of the outer planets are a study in contrasts. The magnetosphere of Jupiter is dominated by the prodigious plasma output of Io, with losses due to diffusion driven by mass loading. At Saturn, the small icy satellites are the major sources of plasma for the inner magnetosphere. The low mass loading rates there imply that the densities of the plasma tori are limited by dissociative recombination, rather than diffusive transport. At Uranus, the icy satellites are negligible plasma sources compared to the input from the extended neutral hydrogen cloud and the ionosphere. Convection driven by the solar wind penetrates deep into the inner magnetosphere because of the unique orientation of the rotation axis of Uranus. The expected magnetosphere of Neptune is similar to that of Saturn and Jupiter, with Triton, the ring arcs, and the planet as possible plasma sources. The Voyager 2 encounter with Neptune holds out the hope of a passage through a nonterrestrial auroral region, a unique event in planetary exploration.

  15. Heavy ion formation in Titan's ionosphere: Magnetospheric introduction of free oxygen and a source of Titan's aerosols?

    Microsoft Academic Search

    E. C. Sittler Jr.; A. Ali; J. F. Cooper; R. E. Hartle; R. E. Johnson; A. J. Coates; D. T. Young

    2009-01-01

    Discovery by Cassini's plasma instrument of heavy positive and negative ions within Titan's upper atmosphere and ionosphere has advanced our understanding of ion neutral chemistry within Titan's upper atmosphere, primarily composed of molecular nitrogen, with ~2.5% methane. The external energy flux transforms Titan's upper atmosphere and ionosphere into a medium rich in complex hydrocarbons, nitriles and haze particles extending from

  16. 3D Multi-fluid Model of the Coupled Ion and Neutral Interaction between Titan's Ionosphere and Saturn's Magnetosphere

    Microsoft Academic Search

    D. S. Snowden; R. Winglee

    2009-01-01

    The interaction between plasma in Saturn's magnetosphere and Titan's ionosphere is complex because of the high density of neutral particles in Titan's ionosphere, the variability of Saturn's magnetosphere, and the variation of solar zenith angle as Titan orbits around Saturn's magnetosphere. Modeling this interaction can be difficult because 1-D and 2-D atmospheric models that include detailed chemistry cannot capture the

  17. Cubesat-Based Dtv Receiver Constellation for Ionospheric Tomography

    NASA Astrophysics Data System (ADS)

    Bahcivan, H.; Leveque, K.; Doe, R. A.

    2013-12-01

    The Radio Aurora Explorer mission, funded by NSF's Space Weather and Atmospheric Research program, has demonstrated the utility of CubeSat-based radio receiver payloads for ionospheric research. RAX has primarily been an investigation of microphysics of meter-scale ionospheric structures; however, the data products are also suitable for research on ionospheric effects on radio propagation. To date, the spacecraft has acquired (1) ground-based UHF radar signals that are backscattered from meter-scale ionospheric irregularities, which have been used to measure the dispersion properties of meter-scale plasma waves and (2) ground-based signals, directly on the transmitter-spacecraft path, which have been used to measure radio propagation disturbances (scintillations). Herein we describe the application of a CubeSat constellation of UHF receivers to expand the latter research topic for global-scale ionospheric tomography. The enabling factor for this expansion is the worldwide availability of ground-based digital television (DTV) broadcast signals whose characteristics are optimal for scintillation analysis. A significant part of the populated world have transitioned, or soon to be transitioned, to DTV. The DTV signal has a standard format that contains a highly phase-stable pilot carrier that can be readily adapted for propagation diagnostics. A multi-frequency software-defined radar receiver, similar to the RAX payload, can measure these signals at a large number of pilot carrier frequencies to make radio ray and diffraction tomographic measurements of the ionosphere and the irregularities contained in it. A constellation of CubeSats, launched simultaneously, or in sequence over years, similar to DMSPs, can listen to the DTV stations, providing a vast and dense probing of the ionosphere. Each spacecraft can establish links to a preprogrammed list of DTV stations and cycle through them using time-division frequency multiplexing (TDFM) method. An on board program can sort the frequencies and de-trend the phase variations due to spacecraft motion. For a single channel and a spacecraft-DTV transmitter path scan, TEC can be determined from the incremental phase variations for each channel. Determination of the absolute TEC requires knowledge of the absolute phase, i.e., including the number of 2? cycles. The absolute TEC can be determined in the case of multi-channel transmissions from a single tower (most towers house multiple television stations). A CubeSat constellation using DTV transmissions as signals of opportunity is a composite instrument for frontier ionospheric research. It is a novel application of CubeSats to understand the ionospheric response to solar, magnetospheric and upper atmospheric forcing. Combined tomographic measurements of ionospheric density can be used to study the global-scale ionospheric circulation and small-scale ionospheric structures that cause scintillation of trans-ionospheric signals. The data can support a wide range of studies, including Sub-auroral Polarization Streams (SAPS), low latitude plasma instabilities and the generation of equatorial spread F bubbles, and the role of atmospheric waves and layers and sudden stratospheric warming (SSW) events in traveling ionospheric disturbances (TID).

  18. Convection in Supernova Explosions

    NASA Astrophysics Data System (ADS)

    Benz, W.; Herant, M.; Colgate, S. A.

    1992-12-01

    We present the results of 2D numerical simulations of the early phase (t <= 1s) of a supernova explosion. The explosion is powered by neutrino absorption on free nucleons and neutrino scattering by electrons. We also include energy losses through neutrino emission following electron or positron capture by protons and neutrons as well as plasma neutrino emission processes. We show that neutrino heating results in a strongly convective region close to the neutron star. Hot material quickly rises whereas cold material is sinking towards the proto-neutron star. By removing the hot material from the vicinity of the neutron star, this large scale convection prevents overheating and hence limits energy losses through neutrino emission. In addition, the rising bubbles drive a strong shock outwards which eventually will lead to a successful explosion. The convective pattern is found to choose the largest mode possible in the computational domain. It follows that convective motions do not average out resulting in a net asymmetry of the explosion. If this asymmetry is confirmed by three-dimensional simulations, it could easily explain the observed high velocity dispersion of pulsars.

  19. Magnetic field aligned currents and the structure of the auroral ionosphere

    NASA Astrophysics Data System (ADS)

    Hruska, A.

    A relation between the magnetic field aligned current (FAC) and other physical quantities characterizing the plasma is discussed with particular attention paid to a description of the FACs in the ionosphere. The ionospheric FACs are related to the properties of the vector field of the total mechanical force G, acting on a volume element of the multicomponent ionospheric gas. The FACs flow in the ionosphere if and only if the dot product of B and curl G does not equal 0. The vorticity of G is determined mainly by the horizontal gradients of the total atmospheric density (rho) in the auroral oval. The FACs observed on the polar orbiting satellites are related to the enhancement of (rho) in the auroral zone ionosphere.

  20. Artificial Ionospheric Heating Experiments Conducted by a Magnetosphere-Ionosphere Coupling Model

    NASA Astrophysics Data System (ADS)

    Stevens, R. J.; Otto, A.; Krzykowski, M.; Solie, D.

    2007-12-01

    This presentation discusses computational dynamics and results of artificial heating in the ionosphere. The results are then compared to experiments including a geophysical experiment conducted at the Polar Aeronomy and Radio Science Summer School (PARS) in conjunction with the High Frequency Active Auroral Research Program (HAARP) The computational model includes the following terms: ion inertia, Ohm's law (Hall term, electron pressure term, electron neutral and electron ion collisions), ionization, recombination, electron energy (heat advection, conduction, heating through ionization, ohmic heating, gravity, energy loss to neutrals and ions), as well as parameterized collisions frequencies, and a height resolved neutral atmosphere. Atmospheric conditions for the time of the experiment (plasma density, temperature, etc) are used as initial conditions. The power and frequency of the heater facility are then used to compute the heating of the ionosphere. Data processing for the experiment and model are ongoing.

  1. Hardware and software complex monitoring the Earth ionosphere

    NASA Astrophysics Data System (ADS)

    Smirnov, Vladimir; Smirnova, Elena; Skobelkin, Vladimir; Tynyankin, Sergey

    The complex structure of the propagation medium, as well as continuous change in time ionospheric plasma parameters affect the propagation of radio waves. Therefore, objectives of the study processes in the ionosphere associated with both the practical tasks of ensuring stable operation of radiocommunication systems and with no less important scientific - research tasks of monitoring near-Earth space. A promising approach to the control of the ionosphere based on the method of radio occultation and to identify the main ionospheric parameters ( total electron content of the critical frequency and height of the ionospheric layer F2) on the results of the reception and signal processing of satellite navigation systems GLONASS and GPS. To solve this problem the theory for solving the inverse problem of radio sounding of the ionosphere on the track satellite-the Earth developed. It based on the use of functional connections parameters probing signals and their propagation medium and the mathematical apparatus of solutions of Fredholm integral equations of the 1st kind, belonging to the class of inverse ill-posed problems of atmospheric refraction. On its basis the continuous monitoring technology designed for the reconstruction of the spatiotemporal structure of the ionosphere and solving operational control and the total electron content of the ionosphere by radio translucence method with using radio navigation satellite system GPS/GLONASS. Based on developed technology of continuous monitoring an automated hardware and software complex intended for determining the parameters of altitude distribution of the electron density of the ionosphere of the Earth designed. It uses the information of the navigation satellite system GPS/GLONASS and works in real time. Automated hardware-software system designed based on dual-frequency receiver firm NovAtel, operating signals navigation satellite systems GPS/GLONASS. The complex allows determine the parameters of the Earth's ionosphere by radio translucence method on track satellite - the Earth simultaneously 10-20 azimuthal directions over the territory, an area of about 3 million square km’s.

  2. JOURNAL OF GEOPHYSICAL RESEARCH: SPACE PHYSICS, VOL. 118, 25932617, doi:10.1002/jgra.50249, 2013 Numerical modeling of the large-scale neutral and plasma responses

    E-print Network

    Vadas, Sharon

    , 1 TECU = 1016 el m­2), and hmF20 5­50 km. The large-scale traveling ionospheric disturbances (LSTIDs the response of the thermosphere and ionosphere to gravity waves (GWs) excited by 6 h of deep convection] Gravity waves (GWs) have been observed in the ther- mosphere and ionosphere for decades [Hocke

  3. IONOTOMO: A new approach for ionospheric tomography using OTH radar

    NASA Astrophysics Data System (ADS)

    Rummel, R. F.; Gruber, T.; Ihde, J.; Liebsch, G.; Sideris, M. G.; Rangelova, E. V.; Woodworth, P. L.; Hughes, C. W.; Gerlach, C.

    2011-12-01

    Tomography techniques have been recently developed to reconstruct electron density in the ionosphere. Most of the recent methods are based on the inversion of the Total Electron Content (TEC) measured by ground-based GPS receivers (e.g., Garcia & Crespon). Notwithstanding the high-density of the stations coverage, as a consequence of the high frequency of the GPS signals, the inversion of the TEC-GPS measurements mainly reconstructs the electron density of the F2 region, where the ionosphere reaches the maximum of ionization, neglecting the lower ionosphere regions. Close to the ionospheric tomography by GPS, additional studies in ionospheric tomography explore HF propagation by OTH radar (Fridman and Fridman, 1994; Ruelle and Landeau, 1994; Landeau et al., 1997; Fridman, 1998). Those works are only based on the inversion of the leading edge echo curve, neglecting valuable informations present in the OTH radar data. To overcome those limits, we set up a new ionospheric tomography 3D method, based on ray-tracing theory and achieving the full analysis of over-the-horizon (OTH) radar data. The major advance of our methodology is taking into account, numerically and jointly, not only the speed variation of EM wave induced by the electron density variation but also the perturbation in the raypath, both necessary for the OTH radar inversion. We present here the originality and the advantages of our method with a full set of synthetic benchmark highlighting the sensitivity of our tomography to the plasma heterogeneities. Additionally, we show the possibility to integrate GPS-TEC data as well as satellite TEC occultations to our tomographic method, for a complete joint inversion capable to reconstruct the entire ionosphere. [Fridman and Fridman, 1994] J. Atmos. Terr. Phys., 56, 115-131, 1994. [Ruelle and Landeau, 1994] J. Atmos. Terr. Phys., 56, 103-114, 1994. [Landeau et al., 1997] J. Atm. Solar Terr. Phys., 59, 125-138, 1997. [Fridman, 1998] Radio Sci., 33, 1159-1171, 1998.

  4. Ion escape fluxes from the terrestrial high-latitude ionosphere

    NASA Technical Reports Server (NTRS)

    Barakat, A. R.; Schunk, R. W.; Moore, T. E.; Waite, J. H., Jr.

    1987-01-01

    In this paper, the hydrodynamic transport equations for H(+) and O(+) are solved, including the important dynamic, collisional, and chemical effects that operate in the F region ionosphere below regions of ion acceleration. It is found that the most important parameter controlling the amount of O(+) in plasma outflows is the total ion flux demand imposed on the ionosphere by the higher-altitude acceleration region. The O(+) content is further modulated by the temperature of the exosphere and the resultant composition in the topside ionosphere, and by the location of the lower boundary of the ion acceleration region relative to the crossover altitude, where O and H have equal densities. As solar activity increases, the limiting O(+) escape flux increases, while the limiting H(+) escape flux decreases.

  5. Observation of ICME Interaction with the Martian Ionosphere

    NASA Astrophysics Data System (ADS)

    Livi, Roberto; McFadden, James P.; Luhmann, Janet; Mitchell, David L.; Jakosky, Bruce; Halekas, Jasper; Connerney, Jack

    2015-04-01

    Using preliminary data from the MAVEN plasma and magnetic field instruments we observe the interaction between an Interplanetary Coronal Mass Ejection (ICME) event and Mars’ ionospheric environment. The ICME onset is observed on October 17th 2014 at 23:00, closely coinciding with the arrival of Comet Siding Spring, and is followed by a compression of the magnetosheath and ionosphere. After the apparent passage of the ICME, on October 18th at 09:00 the magnetosheath drastically expands relative to nominal conditions prior to the ICME arrival. Data availability is only limited during the expansion phase of Mars’ ionospheric environment. These phenomena have been previously observed using MEX data (e.g. Opgenoorth et al., 2013 and Dubini et al., 2009), which also show an increase of ion outflow from the upper atmosphere. We will use MAVEN data, together with its high resolution and magnetic field measurements, to expand upon these results.

  6. Minimal Joule dissipation models of magnetospheric convection

    NASA Technical Reports Server (NTRS)

    Barbosa, D. D.

    1988-01-01

    This paper gives a topical review of theoretical models of magnetospheric convection based on the concept of minimal Joule dissipation. A two-dimensional slab model of the ionosphere featuring an enhanced conductivity auroral oval is used to compute high-latitude electric fields and currents. Mathematical methods used in the modeling include Fourier analysis, fast Fourier transforms, and variational calculus. Also, conformal transformations are introduced in the analysis, which enable the auroral oval to be represented as a nonconcentric, crescent-shaped figure. Convection patterns appropriate to geomagnetic quiet and disturbed conditions are computed, the differentiating variable being the relative amount of power dissipated in the magnetospheric ring current. When ring current dissipation is small, the convection electric field is restricted to high latitudes (shielding regime), and when it is large, a significant penetration of the field to low latitudes occurs, accompanied by an increase in the ratio of the region I current to the region 2 current.

  7. Tohoku earthquake shook the ionosphere

    Microsoft Academic Search

    Ernie Balcerak

    2011-01-01

    The giant 11 March 2011 magnitude 9 Tohoku earthquake not only shook the Earth and caused devastating tsunamis but also rattled the ionosphere, according to a new study. The surface seismic waves and tsunamis triggered waves in the atmosphere. These atmospheric waves propagated upward into the ionosphere, creating ripples in ionized gas nearly 350 kilometers above the Earth. Liu et

  8. Titan's upper atmospheric structure and ionospheric composition

    NASA Astrophysics Data System (ADS)

    Westlake, Joseph H.

    This Dissertation investigates the density structure of the neutral upper atmosphere and the composition of the ionosphere of Titan through Cassini observations. The highly extended atmosphere of Titan consists primarily of N2, CH4, and H2. The focus is on data extracted from the Ion and Neutral Mass Spectrometer (INMS) and the Cassini Plasma Spectrometer (CAPS) instruments onboard Cassini. The INMS, which is fundamentally a quadrupole mass spectrometer, measures the abundance of neutral and ion components with masses of 1--8 and 12--99 Da. The CAPS instrument consists of three subsystems of which the Ion Beam Spectrometer (CAPS-IBS) is used in this study to derive mass spectra of thermal ions up to 400 Da. in mass in Titan's ionosphere. From measurements of molecular nitrogen in Titan's upper atmosphere an atmospheric scale height is derived implying an effective temperature. From an analysis of 29 targeted flybys of Titan we find that the thermosphere is isothermal from an altitude of 1050 km to the exobase height with an average effective temperature of 153 K. The scale height, and hence the effective temperature, is found to be highly variable. We assess this variability against the relevant geospatial, solar, and magnetospheric parameters to determine which are highly correlated to the effective temperatures. Titan's thermospheric temperature is found to be controlled by variations in the magnetospheric plasma environment. No correlation is found to exist with respect to geospatial parameters (i.e., latitude or longitude) and anti-correlation is found with solar parameters implying that Titan's nightside is hotter than its dayside. Furthermore, Titan's thermosphere is found to respond to plasma forcings on timescales less than one Titan day. To investigate the composition of Titan's ionosphere we present a 1D photochemical model of Titan's dayside ionosphere constrained by Cassini measurements. We show that the production of the primary products of photoionization match the INMS data to within 20%. The major ions, CH+5,C2H+ 5 , and HCNH+, are discussed at length and an investigation of the processes controlling their modeled densities is presented. We then present the ion density profiles for the major hydrocarbons in the C3--C6 groups and the major nitrogen-containing ions up to the C4 group. We find that significant chemistry in the nitrogen containing hydrocarbons is missing from previous models and suggest pathways for the growth of these molecules. We also find that the chemistry of Titan's ionosphere is not necessarily dominated by proton exchange processes and that significant molecular growth should be expected through associative ion-molecule reactions. The composition of the ions observed by the Ion Beam Spectrometer (CAPS-IBS) are analyzed with a specific emphasis on those larger than benzene (C 6H6). The CAPS-IBS mass spectra are found to have several peaks corresponding to ions having up to 14 carbon atoms with significant densities and masses up to 400 Da. Fits to the high mass ion spectra determine that each observed peak grouping must contain more than one ion of substantial density possibly indicating some degree of nitrogen incorporation. We compare the high mass ion spectra to various laboratory experiments which have produced large hydrocarbons or tholins through plasma processing of N2, CH4, and various simple hydrocarbons. We conclude from these comparisons that it is likely that Titan's ionospheric chemistry proceeds to higher mass through the reactions of C2 hydrocarbons and nitrogen containing hydrocarbons. Density profiles of the C8--C13 groups are presented from the CAPS-IBS data which show a region of initiation at altitudes above 1050 km and below 1200 km followed by a stagnation and drop-off at the lowest altitudes. We present modeled density profiles of the ions in the C6 and larger groups using an empirical model.

  9. Moist Convection

    NASA Astrophysics Data System (ADS)

    Gierasch, Peter J.

    2014-11-01

    On Jupiter there is little doubt that the water condensation level is the seat of moist convective activity. Two major differences between Earth and Jupiter are the importance of the relatively high molecular weight of water on Jupiter and the altered bottom boundary condition on Jupiter. In addition, the triggering mechanism for convection by large scale motion is not yet understood. On Saturn the Great Storm came at a good time for Cassini observations, and the most interesting is the reversal in direction of the vertical motion tracers parahydrogen and potential temperature. Uranus and Neptune appear, on the basis of much less information, to be more exotic. With a high degree of uncertainty we here conjecture that moist convection on these planets is affected by hydrogen ortho-para latent heat in addition to water and methane and that intermittency is the outcome in both the spatial and temporal domains.

  10. Features of steady magnetospheric convection

    SciTech Connect

    Yahnin, A.; Malkov, M.V. [Polar Geophysical Institute, Apatity (Russian Federation)] [Polar Geophysical Institute, Apatity (Russian Federation); Sergeev, V.A. [Univ. of St. Petersburg (Russian Federation)] [Univ. of St. Petersburg (Russian Federation); Pellinene, R.J.; Aulamo, O. [Finnish Meteorological Institute, Helsinki (Finland)] [Finnish Meteorological Institute, Helsinki (Finland); Vennerstroem, S.; Friis-Christensen, E.; Lassen, K.; Danielsen, C. [Danish Meteorological Institute, Copenhagen (Denmark)] [Danish Meteorological Institute, Copenhagen (Denmark); Craven, J.D. [Univ. of Alaska, Fairbanks (South Africa)] [and others] [Univ. of Alaska, Fairbanks (South Africa); and others

    1994-03-01

    The large-scale patterns of ionospheric convection and particle precipitation are described during two intervals of steady magnetospheric convection (SMC) on November 24, 1981. The unique data set used in the analysis includes recordings from the worldwide network of magnetometers and all-sky cameras, global auroral images from the DE 1 spacecraft, and particle precipitation data from low-altitude NOAA 6 and NOAA 7 spacecraft. The data show that intense magnetospheric convection continued during more than 10 hours under the steady southward interplanetary magnetic field without any distinct substorm signatures. All data sets available confirmed the stable character of the large-scale magnetospheric configuration during this period. In particular, the magnetic flux threading the polar cap was stable (within 10%) during 3.5 hours of continued DE 1 observations. The dayside cusp was located at an unusually low latitude (70{degrees} CGL). The nightside auroral pattern consisted of two distinct regions. The diffuse aurora in the equatorward half of the expanded (10{degrees} wide) auroral oval was well-separated from the bright, active auroral forms found in the vicinity of the poleward boundary of the oval. The twin-vortex convection pattern had no signature of the Harang discontinuity; its nightside {open_quotes}convection throat{close_quotes} was spatially coincident with the poleward active auroras. This region of the auroral oval was identified as the primary site of the short-lived transient activations during the SMC intervals. The energetic particle observations show that the auroral oval was identified as the primary site of the short-lived transient activations during the SMC intervals. The energetic particle observations show that the auroral precipitation up to its high-latitude limit is on closed field lines and that particle acceleration up to > 30-keV energy starts close to this limit. 34 refs., 11 figs., 1 tab.

  11. Currents and Electrojets in the Ionosphere of Mars

    NASA Astrophysics Data System (ADS)

    Fillingim, Matthew O.; Lillis, Robert; Brain, D. A.

    2015-04-01

    How the solar wind interacts with a planetary object depends upon the object's properties such as the presence of a magnetic field or an atmosphere. An unmagnetized object cannot stand-off the solar wind unless it possess a substantial atmosphere which can be ionized by solar radiation creating a conductive ionosphere. Currents can then be induced in the ionosphere; these currents act to cancel out the external solar wind magnetic field preventing it from reaching the surface. Here we present simple analytical calculations of such induced currents in the ionosphere of Mars. We consider currents in the ionospheric dynamo region which can be driven by thermospheric winds as well as currents driven by electric fields (i.e., plasma motion through the neutrals). We include in these estimates the effects of "equatorial-type" electrojets due to vertical conductivity gradients in the presence of horizontal magnetic fields. In addition, we consider "auroral-type" electrojets due to horizontal conductivity gradients resulting from particle precipitation and/or large variations in the magnetic field strength near vertical cusps in strong crustal field regions. The direction of the external driver is important. In some cases, the secondary current adds to the primary current creating electrojets. In other cases, the secondary current can cancel or nearly cancel the primary current resulting in very weak net currents. These results can give us insights into how external magnetic fields are effectively screened out by induced currents and how these induced currents can influence ionospheric dynamics around unmagnetized objects.

  12. A Forecasting Ionospheric Real-time Scintillation Tool (FIRST)

    NASA Astrophysics Data System (ADS)

    Redmon, Robert J.; Anderson, David; Caton, Ron; Bullett, Terence

    2010-12-01

    Transionospheric radio waves propagating through an irregular ionosphere with plasma depletions, or "bubbles," are subject to sporadic enhancement and fading commonly referred to as scintillation. Knowledge of the current ionospheric condition allows system operators to distinguish between compromises due to the radio environment and system induced failures, while a forecast of the same provides the opportunity for operators to take appropriate actions to mitigate the effects and optimize service. This paper describes a technique that uses the readily accessible ionospheric characteristic h'F from ground-based ionospheric sounder data near the geomagnetic equator to forecast the occurrence or nonoccurrence of low-latitude scintillation activity in VHF/UHF bands. We illustrate the development of the Forecasting Ionospheric Real-time Scintillation Tool and its real-time capability for forecasting scintillation activity. Finally, we have found that there exists a threshold in the h'F value at 1930 LT that corresponds to the onset of scintillation activity in the Peruvian longitude sector, which is found to decrease with decreasing F10.7 cm fluxes in a linear manner.

  13. Global ionospheric dynamics and electrodynamics during geomagnetic storms (Invited)

    NASA Astrophysics Data System (ADS)

    Mannucci, A. J.; Tsurutani, B.; Verkhoglyadova, O. P.; Komjathy, A.; Butala, M. D.

    2013-12-01

    Globally distributed total electron content (TEC) data has become an important tool for exploring the consequences of storm-time electrodynamics. Magnetosphere-ionosphere coupling during the main phase is responsible for the largest ionospheric effects observed during geomagnetic storms, mediated by global scale electrodynamics. Recent research using case studies reveals a complex picture of M-I coupling and its relationship to interplanetary drivers such as the solar wind electric field. Periods of direct coupling exist where the solar wind electric field is strongly correlated with prompt penetration electric fields, observed as enhanced vertical plasma drifts or an enhanced electrojet in the daytime equatorial ionosphere. Periods of decoupling between low latitude electric fields and the solar wind electric field are also observed, but the factors distinguishing these two types of response have not been clearly identified. Recent studies during superstorms suggest a role for the transverse (y-component) of the interplanetary magnetic field, which affects magnetospheric current systems and therefore may affect M-I coupling, with significant ionospheric consequences. Observations of the global ionospheric response to a range of geomagnetic storm intensities are presented. Scientific understanding of the different factors that affect electrodynamic aspects of M-I coupling are discussed.

  14. Detection of Ionospheric Alfven Resonator Signatures Onboard C/NOFS: Implications for IRI Modeling

    NASA Technical Reports Server (NTRS)

    Simoes, F.; Klenzing, J.; Ivanov, S.; Pfaff, R.; Rowland, D.; Bilitza, D.

    2011-01-01

    The 2008-2009 long-lasting solar minimum activity has been the one of its kind since the dawn of space age, offering exceptional conditions for investigating space weather in the near-Earth environment. First ever detection of Ionospheric Alfven Resonator (IAR) signatures in orbit offers new means for investigating ionospheric electrodynamics, namely MHD (MagnetoHydroDynamics) wave propagation, aeronomy processes, ionospheric dynamics, and Sun-Earth connection mechanisms at a local scale. Local and global plasma density heterogeneities in the ionosphere and magnetosphere allow for formation of waveguides and resonators where magnetosonic and shear Alfven waves propagate. The ionospheric magnetosonic waveguide results from complete magnetosonic wave reflection about the ionospheric F-region peak, where the Alfven index of refraction presents a maximum. MHD waves can also be partially trapped in the vertical direction between the lower boundary of the ionosphere and the magnetosphere, a resonance mechanism known as IAR. In this work we present C/NOFS (Communications/Navigation Outage Forecasting System) Extremely Low Frequency (ELF) electric field measurements related to IAR signatures, discuss the resonance and wave propagation mechanisms in the ionosphere, and address the electromagnetic inverse problem from which electron/ion distributions can be derived. These peculiar IAR electric field measurements provide new, complementary methodologies for inferring ionospheric electron and ion density profiles, and also contribute for the investigation of ionosphere dynamics and space weather monitoring. Specifically, IAR spectral signatures measured by C/NOFS contribute for improving the International Reference Ionosphere (IRI) model, namely electron density and ion composition.

  15. Coupling of magnetopause-boundary layer to the polar ionosphere

    NASA Technical Reports Server (NTRS)

    Wei, C. Q.; Lee, L. C.

    1993-01-01

    The plasma dynamics in the low-latitude boundary layer and its coupling to the polar ionosphere under boundary conditions at the magnetopause are investigated. In the presence of a driven plasma flow along the magnetopause, the Kelvin-Helmholtz instability can develop, leading to the formation and growth of plasma vortices in the boundary layer. The finite ionospheric conductivity leads to the decay of these vortices. The competing effect of the formation and decay of vortices leads to the formation of strong vortices only in a limited region. Several enhanced field-aligned power density regions associated with the boundary layer vortices and the upward field-aligned current (FAC) filaments can be found along the postnoon auroral oval. These enhanced field-aligned power density regions may account for the observed auroral bright spots.

  16. Flux-tube analysis of ionospheric L-band scintillation

    NASA Astrophysics Data System (ADS)

    Shume, E.; Mannucci, A.; Butala, M.; Pi, X.; Valladares, C. E.

    2012-12-01

    This presentation discusses flux-tube analysis of L-band scintillation of signals from GEO stationary satellites over equatorial and low-latitude ionosphere. The analysis uses scintillation data from chain of receivers measured by the LISN (Low-Latitude Ionospheric Sensors) network. Vertical TEC over these regions estimated by the GIPSY package is also utilized in the research. The presentation will mainly address the following science questions: (1) What are the dominant scales of plasma irregularities in the evening which cause L-band scintillations? (2) Are scintillation causing plasma irregularities observed simultaneously or is there a time delay along a flux-tube? (3) To what degree the plasma irregularities as inferred from the analysis are anisotropic in the east-west as well as north-south directions? (4) What are the implications for L-band space missions?

  17. The sheath/ionosphere boundary layer at Venus

    NASA Technical Reports Server (NTRS)

    Szego, K.; Shapiro, V. D.; Ride, S. K.; Nagy, A. F.; Shevchenko, V. I.

    1995-01-01

    At Venus the interaction of the shocked solar wind and cold planetary ions takes place in the dayside mantle. The shocked solar wind is a warm, drifting Maxwellian plasma whereas the planetary plasma is cold; the plasma in the mantle is strongly magnetized. The coexistence of these two populations is unstable, and it leads to wave excitations that organize the energy and momentum exchange between the shocked solar wind and the plasma of planetary origin. The source of the free energy is the solar wind. The intensive wave activity seen in the 100 Hz channel of the wave instrument onboard the Pioneer-Venus Orbiter in the dayside mantle region of Venus can be identified as almost electrostatic VLF waves excited by the kinetic branch of the modified two-stream lower hybrid instability. The waves interact with the particles, and the planetary plasma is heated and accelerated outside the ionosphere, close to its upper boundary. This way solar wind scavenges the ionosphere, and planetary ions leave the planetary magnetosphere. A portion of the wave energy is capable of penetrating directly into the ionosphere and heating it.

  18. Titan Ion Composition at Magnetosphere-Ionosphere Transition Region

    NASA Technical Reports Server (NTRS)

    Sittler, Edward C.; Hartle, R. E.; Shappirio, M.; Simpson, D. J.; COoper, J. F.; Burger, M. H.; Johnson, R. E.; Bertucci, C.; Luhman, J. G.; Ledvina, S. A.; Szego, K.; Coates, A. J.; Young, D. T.

    2006-01-01

    Using Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS) ion composition data, we will investigate the compositional changes at the transition region between Saturn's magnetospheric flow and Titan's upper ionosphere. It is this region where scavenging of Titan's upper ionosphere can occur, where it is then dragged away by the magnetospheric flow as cold plasma for Saturn's magnetosphere. This cold plasma may form plumes as originally proposed by (1) during the Voyager 1 epoch. This source of cold plasma may have a unique compositional signature such as methane group ions. Water group ions that are observed in Saturn's outer magnetosphere (2,3) are relatively hot and probably come from the inner magnetosphere where they are born from fast neutrals escaping Enceladus (4) and picked up in the outer magnetosphere as hot plasma (5). This scenario will be complicated by pickup methane ions within Titan's mass loading region, as originally predicted by (6) based on Voyager 1 data and observationally confirmed by (3,7) using CAPS IMS data. But, CH4(+) ions or their fragments can only be produced as pickup ions from Titan's exosphere which can extend beyond the transition region of concern here, while CH5(+) ions can be scavenged from Titan's ionosphere. We will investigate these possibilities.

  19. Real-Time Ionospheric Characterization and Modeling

    Microsoft Academic Search

    Suman Ganguly; Andrew Brown

    Complete descriptions of spatial and temporal distributions of the ionosphere are obtained using a real-time ionospheric characterization (RTIC) system developed at CRS (and described by Ganguly and Brown, 2001). The system accepts data from various sources, regions, and times, then assimilates these data within the framework of physical ionospheric models, providing a 4-D description of the ionosphere anywhere in the

  20. Tsunami signature in the ionosphere: A simulation of OTH radar observations

    NASA Astrophysics Data System (ADS)

    CoïSson, Pierdavide; Occhipinti, Giovanni; Lognonné, Philippe; Molinié, Jean-Philippe; Rolland, Lucie M.

    2011-12-01

    In the last ten years ionospheric anomalies following major earthquakes and tsunamis have been detected. Global Positioning System (GPS) and altimeters have been proven effective for this purpose, through Total Electron Content (TEC) measurement. Most of these ionospheric anomalies are deterministic and reproducible by numerical modeling via the coupling mechanism through ocean, neutral atmosphere and ionosphere. Numerical modeling supplies also useful support in the estimation of expected ionospheric effects and in the exploration and identification of new techniques to detect ionospheric tsunami signatures. We explore here a new ground-based technique, nominally the use of over-the-horizon (OTH) radars, for tsunami detection through ionospheric monitoring. OTH radars operate in High Frequency (HF) band and sounding the bottomside ionosphere they could anticipate the detection of tsunami-driven Internal Gravity Waves (IGW). To validate this hypothesis, we use HF numerical ray-tracing to simulate synthetic OTH radar measurements through a 3D tsunami-driven IGW ionospheric model. Our simulations clearly identify the tsunami signature in the OTH radar measurements one hour and a half before the tsunami arrival on the coast. The large coverage of OTH radar and its sensitivity to plasma anomalies open new perspectives in the oceanic monitoring and future tsunami warning systems.

  1. Solitons and ionospheric modification

    NASA Technical Reports Server (NTRS)

    Sheerin, J. P.; Nicholson, D. R.; Payne, G. L.; Hansen, P. J.; Weatherall, J. C.; Goldman, M. V.

    1982-01-01

    The possibility of Langmuir soliton formation and collapse during ionospheric modification is investigated. Parameters characterizing former facilities, existing facilities, and planned facilities are considered, using a combination of analytical and numerical techniques. At a spatial location corresponding to the exact classical reflection point of the modifier wave, the Langmuir wave evolution is found to be dominated by modulational instability followed by soliton formation and three-dimensional collapse. The earth's magnetic field is found to affect the shape of the collapsing soliton. These results provide an alternative explanation for some recent observations.

  2. Production of small-scale Alfvén waves by ionospheric depletion, nonlinear magnetosphere-ionosphere coupling and phase mixing

    NASA Astrophysics Data System (ADS)

    Russell, A. J. B.; Wright, A. N.; Streltsov, A. V.

    2013-04-01

    Rockets and satellites have previously observed small-scale Alfvén waves inside large-scale downward field-aligned currents, and numerical simulations have associated their formation with self-consistent magnetosphere-ionosphere coupling. The origin of these waves was previously attributed to ionospheric feedback instability; however, we show that they arise in numerical experiments in which the instability is excluded. A new interpretation is proposed in which strong ionospheric depletion and associated current broadening (a nonlinear steepening/wave-breaking process) form magnetosphereionosphere waves inside a downward current region and these oscillations drive upgoing inertial Alfvén waves in the overlying plasma. The resulting waves are governed by characteristic periods, which are a good match to previously observed periods for reasonable assumed conditions. Meanwhile, wavelengths perpendicular to the magnetic field initially map to an ionospheric scale comparable to the electron inertial length for the low-altitude magnetosphere, but become shorter with time due to frequency-based phase mixing of boundary waves (a new manifestation of phase mixing). Under suitable conditions, these could act as seeds for the ionospheric feedback instability.

  3. Ionization balance in Titan's nightside ionosphere

    NASA Astrophysics Data System (ADS)

    Vigren, E.; Galand, M.; Yelle, R. V.; Wellbrock, A.; Coates, A. J.; Snowden, D.; Cui, J.; Lavvas, P.; Edberg, N. J. T.; Shebanits, O.; Wahlund, J.-E.; Vuitton, V.; Mandt, K.

    2015-03-01

    Based on a multi-instrumental Cassini dataset we make model versus observation comparisons of plasma number densities, nP = (nenI)1/2 (ne and nI being the electron number density and total positive ion number density, respectively) and short-lived ion number densities (N+, CH2+, CH3+, CH4+) in the southern hemisphere of Titan's nightside ionosphere over altitudes ranging from 1100 and 1200 km and from 1100 to 1350 km, respectively. The nP model assumes photochemical equilibrium, ion-electron pair production driven by magnetospheric electron precipitation and dissociative recombination as the principal plasma neutralization process. The model to derive short-lived-ion number densities assumes photochemical equilibrium for the short-lived ions, primary ion production by electron-impact ionization of N2 and CH4 and removal of the short-lived ions through reactions with CH4. It is shown that the models reasonably reproduce the observations, both with regards to nP and the number densities of the short-lived ions. This is contrasted by the difficulties in accurately reproducing ion and electron number densities in Titan's sunlit ionosphere.

  4. Mesospheric airglow and ionospheric responses to upward-propagating acoustic and gravity waves above tropospheric sources

    NASA Astrophysics Data System (ADS)

    Snively, J. B.; Zettergren, M. D.

    2013-12-01

    The existence of acoustic waves (periods ~1-5 minutes) and gravity waves (periods >4 minutes) in the ionosphere above active tropospheric convection has been appreciated for more than forty years [e.g., Georges, Rev. Geophys. and Space Phys., 11(3), 1973]. Likewise, gravity waves exhibiting cylindrical symmetry and curvature of phase fronts have been observed via imaging of the mesospheric airglow layers [e.g., Yue et al., JGR, 118(8), 2013], clearly associated with tropospheric convection; gravity wave signatures have also recently been detected above convection in ionospheric total electron content (TEC) measurements [Lay et al., GRL, 40, 2013]. We here investigate the observable features of acoustic waves, and their relationship to upward-propagating gravity waves generated by the same sources, as they arrive in the mesosphere, lower-thermosphere, and ionosphere (MLTI). Numerical simulations using a nonlinear, cylindrically-axisymmetric, compressible atmospheric dynamics model confirm that acoustic waves generated by transient tropospheric sources may produce "concentric ring" signatures in the mesospheric hydroxyl airglow layer that precede the arrival of gravity waves. As amplitudes increase with altitude and decreasing neutral density, the modeled acoustic waves achieve temperature and vertical wind perturbations on the order of ~10s of Kelvin and m/s throughout the E- and F-region. Using a coupled multi-fluid ionospheric model [Zettergren and Semeter, JGR, 117(A6), 2012], extended for low-latitudes using a 2D dipole magnetic field coordinate system, we investigate acoustic wave perturbations to the ionosphere in the meridional direction. Resulting perturbations are predicted to be detectable by ground-based radar and GPS TEC measurements, or via in situ instrumentation. Although transient and short-lived, the acoustic waves' airglow and ionospheric signatures are likely to in some cases be observable, and may provide important insight into the regional forcing of the MLTI system from tropospheric sources below.

  5. Convection towers

    DOEpatents

    Prueitt, Melvin L. (Los Alamos, NM)

    1994-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

  6. Convection towers

    DOEpatents

    Prueitt, Melvin L. (Los Alamos, NM)

    1995-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

  7. Convection towers

    DOEpatents

    Prueitt, Melvin L. (Los Alamos, NM)

    1996-01-01

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

  8. Modeling Convection

    ERIC Educational Resources Information Center

    Ebert, James R.; Elliott, Nancy A.; Hurteau, Laura; Schulz, Amanda

    2004-01-01

    Students must understand the fundamental process of convection before they can grasp a wide variety of Earth processes, many of which may seem abstract because of the scales on which they operate. Presentation of a very visual, concrete model prior to instruction on these topics may facilitate students' understanding of processes that are largely…

  9. Convection towers

    DOEpatents

    Prueitt, M.L.

    1996-01-16

    Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

  10. Convection Current

    NSDL National Science Digital Library

    The Exploratorium

    2012-06-26

    In this activity, learners make their own heat waves in an aquarium. Warmer water rising through cooler water creates turbulence effects that bend light, allowing you to project swirling shadows onto a screen. Use this demonstration to show convection currents in water as well as light refraction in a simple, visually appealing way.

  11. Convection Activities

    NSDL National Science Digital Library

    This page presents activities related to Convection from the Science & Engineering in the Lives of Students project. Activities include Candle Heat, Freezer Air Temperature, Hot Cup, Pencil Shaving, and Speed Melting. Each activity includes a detailed description, list of the materials needed, science concepts covered, and reflection questions.

  12. Convective equilibrium and mixing-length theory for stellarator reactors

    SciTech Connect

    Ho, D.D.M.; Kulsrud, R.M.

    1985-09-01

    In high ..beta.. stellarator and tokamak reactors, the plasma pressure gradient in some regions of the plasma may exceed the critical pressure gradient set by ballooning instabilities. In these regions, convective cells break out to enhance the transport. As a result, the pressure gradient can rise only slightly above the critical gradient and the plasma is in another state of equilibrium - ''convective equilibrium'' - in these regions. Although the convective transport cannot be calculated precisely, it is shown that the density and temperature profiles in the convective region can still be estimated. A simple mixing-length theory, similar to that used for convection in stellar interiors, is introduced in this paper to provide a qualitative description of the convective cells and to show that the convective transport is highly efficient. A numerical example for obtaining the density and temperature profiles in a stellarator reactor is given.

  13. Kinetic response of ionospheric ions to onset of auroral electric fields

    NASA Technical Reports Server (NTRS)

    Chiu, Y. T.; Kan, J. R.

    1981-01-01

    By examining the exact analytic solution of a kinetic model of collisional interaction of ionospheric ions with atmospheric neutrals in the Bhatnagar-Gross-Krook approximation, we show that the onset of intense auroral electric fields in the topside ionosphere can produce the following kinetic effects: (1) heat the bulk ionospheric ions to approximately 2 eV, thus driving them up to higher altitudes where they can be subjected to collisionless plasma processes; (2) produce a non-Maxwellian superthermal tail in the distribution function; and (3) cause the ion distribution function to be anisotropic with respect to the magnetic field with the perpendicular average thermal energy exceeding the parallel thermal energy.

  14. Kinetic response of ionospheric ions to onset of auroral electric fields

    NASA Technical Reports Server (NTRS)

    Chiu, Y. T.; Kan, J. R.

    1981-01-01

    Examination of the exact analytic solution of a kinetic model of collisional interaction of ionospheric fions with atmospheric neutrals in the Bhatnagar-Gross-Krook approximation, shows that the onset of intense auroral electric fields in the topside ionosphere can produce the following kinetic effects: (1) heat the bulk ionospheric ions to approximately 2 eV, thus driving them up to higher altitudes where they can be subjected to collisionless plasma processes; (2) produce a nonMaxwellian superthermal tail in the distribution function; and (3) cause the ion distribution function to be anisotropic with respect to the magnetic field with the perpendicular average thermal energy exceeding the parallel thermal energy.

  15. A new model of cometary ionospheres

    NASA Technical Reports Server (NTRS)

    Korosmezey, A.; Cravens, T. E.; Nagy, A. F.; Gombosi, T. I.; Mendis, D. A.

    1987-01-01

    The coupled continuity, momentum, and energy equations were solved for ionospheric conditions appropriate for Comet Halley at 1 AU. The numerical scheme used is such that any shock transition appears naturally in the solution and no a priori assumptions are necessary. Solutions were obtained for a number of different assumptions concerning electron heating rates, but all showed that the electron temperatures increase rapidly and significantly at a distance from the nucleus where collisional electron-neutral cooling becomes unimportant. This temperature increase is accompanied by a sharp increase in both the plasma pressure and its associated polarization electric field, causing the supersonic plasma flow to go subsonic. It is not clear at this time whether or not this sonic transition is accompanied by a shock.

  16. Searching for seismo-ionospheric earthquakes precursors: Total Electron Content disturbances before 2005-2006 seismic events

    E-print Network

    Romanovskaya, Yu V; Zolotov, O V; Starikova, N A; Lopatiy, V Z

    2012-01-01

    During earthquakes preparation periods significant disturbances in the ionospheric plasma density are often observed. These anomalies are caused by lithosphere-atmosphere-ionosphere interaction, particularly by the seismic electric field penetrating from the ground surface into the ionosphere. The seismic electric field produces electromagnetic EB drift changing plasma density over the epicenter region and magnetically conjugated area. The paper is devoted to analysis of regular Global Positioning System observations and revelation of seismo-ionospheric precursors of earthquakes in Total Electron Content (TEC) of the ionosphere. Global and regional relative TEC disturbances maps (%) have been plotted for 2005-2006 M6, D<60 km seismic events and analyzed in order to determine general features of precursors. The obtained results agree with the recent published case-study investigations.

  17. Interplanetary Radio Transmission Through Serial Ionospheric and Material Barriers

    SciTech Connect

    Fields, David [ORNL; Kennedy, Robert G [ORNL; Roy, Kenneth I [ORNL; Vacaliuc, Bogdan [ORNL

    2013-01-01

    A usual first principle in planning radio astronomy observations from the earth is that monitoring must be carried out well above the ionospheric plasma cutoff frequency (~5 MHz). Before space probes existed, radio astronomy was almost entirely done above 6 MHz, and this value is considered a practical lower limit by most radio astronomers. Furthermore, daytime ionization (especially D-layer formation) places additional constraints on wave propagation, and waves of frequency below 10-20 MHz suffer significant attenuation. More careful calculations of wave propagation through the earth s ionosphere suggest that for certain conditions (primarily the presence of a magnetic field) there may be a transmission window well below this assumed limit. Indeed, for receiving extraterrestrial radiation below the ionospheric plasma cutoff frequency, a choice of VLF frequency appears optimal to minimize loss. The calculation, experimental validation, and conclusions are presented here. This work demonstrates the possibility of VLF transmission through the ionosphere and various subsequent material barriers. Implications include development of a new robust communications channel, communications with submerged or subterranean receivers / instruments on or offworld, and a new approach to SETI.

  18. The International Reference Ionosphere 2012 - a model of international collaboration

    NASA Astrophysics Data System (ADS)

    Bilitza, Dieter; Altadill, David; Zhang, Yongliang; Mertens, Chris; Truhlik, Vladimir; Richards, Phil; McKinnell, Lee-Anne; Reinisch, Bodo

    2014-02-01

    The International Reference Ionosphere (IRI) project was established jointly by the Committee on Space Research (COSPAR) and the International Union of Radio Science (URSI) in the late sixties with the goal to develop an international standard for the specification of plasma parameters in the Earth's ionosphere. COSPAR needed such a specification for the evaluation of environmental effects on spacecraft and experiments in space, and URSI for radiowave propagation studies and applications. At the request of COSPAR and URSI, IRI was developed as a data-based model to avoid the uncertainty of theory-based models which are only as good as the evolving theoretical understanding. Being based on most of the available and reliable observations of the ionospheric plasma from the ground and from space, IRI describes monthly averages of electron density, electron temperature, ion temperature, ion composition, and several additional parameters in the altitude range from 60 km to 2000 km. A working group of about 50 international ionospheric experts is in charge of developing and improving the IRI model. Over time as new data became available and new modeling techniques emerged, steadily improved editions of the IRI model have been published. This paper gives a brief history of the IRI project and describes the latest version of the model, IRI-2012. It also briefly discusses efforts to develop a real-time IRI model. The IRI homepage is at http://IRImodel.org.

  19. The ionosphere of Triton

    NASA Technical Reports Server (NTRS)

    Majeed, T.; Mcconnell, J. C.; Strobel, D. F.; Summers, M. E.

    1990-01-01

    A model of the atmospheric temperature structure and composition inferred from the Voyager (UVS) solar occultations was used together with a one-dimensional chemical diffusive model to interpret the Voyager Radio Science Spectrometer (RSS) ingress measurements of Triton's electron density. Although N2(+) is the major ion created, N(+) produced by dissociative ionization is the dominant ion. Reaction of thermospheric H2, produced by Lyman-alpha dissociation of CH4 in the lower atmosphere, is the major loss for N(+) ions and maintains these ions in PCSS below 600 km. Solar EUV ionization cannot generate electron densities at the magnitude measured by the RSS experiment and an additional ionization source about 3 x 10 to the 8th ions/sq cm per sec is required. The ionosphere may undergo a transition from PCSS to diffusive control if the N(+) ion production rates were greater than the H2 flux derived from CH4. In this case, the upward flowing H2 is totally converted to H by reaction with N(+) and the remaining N(+) ions recombine radiatively to create an ionosphere under diffusive control above the peak.

  20. Ionospherically reflected proton whistlers

    NASA Astrophysics Data System (ADS)

    Vavilov, D. I.; Shklyar, D. R.

    2014-12-01

    We present experimental observations and detailed investigation of the variety of proton whistlers that includes transequatorial and ionospherically reflected proton whistlers. The latter have previously been indicated from numerical modeling of spectrograms. The study is based on six-component ELF wave data from the Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite which permits to obtain not only spectrograms displaying the power spectral density but also such wave properties as the polarization, wave normal angle, wave refractive index, and normalized parallel component of the Poynting vector. The explanation of various types of proton whistlers is based on the properties of ion cyclotron wave propagation in a multicomponent magnetoplasma, with special consideration of the effect of ion hybrid resonance reflection. Analysis of experimental data is supplemented by numerical modeling of spectrograms that reproduces the main features of experimental ones. As a self-contained result, we provide conclusive experimental evidences that the region illuminated by a lightning stroke in the Earth-ionosphere waveguide may spread over a distance of 4000 km in both hemispheres.