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Full-Text Articles in Physics
Large-Scale Gravity Wave Perturbations In The Mesopause Region Above Northern Hemisphere Midlatitudes During Autumnal Equinox: A Joint Study By The Usu Na Lidar And Whole Atmosphere Community Climate Model, Xuguang Cai, Titus Yuan, Han-Li Liu
Large-Scale Gravity Wave Perturbations In The Mesopause Region Above Northern Hemisphere Midlatitudes During Autumnal Equinox: A Joint Study By The Usu Na Lidar And Whole Atmosphere Community Climate Model, Xuguang Cai, Titus Yuan, Han-Li Liu
Xuguang Cai
To investigate gravity wave (GW) perturbations in the midlatitude mesopause region during boreal equinox, 433h of continuous Na lidar full diurnal cycle temperature measurements in September between 2011 and 2015 are utilized to derive the monthly profiles of GW-induced temperature variance, T′2, and the potential energy density (PED). Operating at Utah State University (42°N, 112°W), these lidar measurements reveal severe GW dissipation near 90km, where both parameters drop to their minima (∼ 20K2 and ∼50m2s−2, respectively). The study also shows that GWs with periods of 3–5h dominate the midlatitude mesopause region during …
Observations Of The Vertical Ion Drift In The Equatorial Ionosphere During The Solar Minimum Period Of 2009, R. A. Stoneback, R. A. Heelis, A. G. Burrell, W. R. Coley, Bela G. Fejer, E. Pacheco
Observations Of The Vertical Ion Drift In The Equatorial Ionosphere During The Solar Minimum Period Of 2009, R. A. Stoneback, R. A. Heelis, A. G. Burrell, W. R. Coley, Bela G. Fejer, E. Pacheco
Bela G. Fejer
[1] The extended solar minimum conditions in 2008 and 2009 presented an opportunity to investigate the ionosphere at lower solar activity levels than previously observed. The Coupled Ion Neutral Dynamics Investigation (CINDI) Ion Velocity Meter (IVM) instrument onboard the Communication/Navigation Outage Forecasting System is used to construct the median meridional (vertical) ion drifts, ion densities, and O+ concentrations during periods of low geomagnetic activity for four characteristic seasons each year spanning late 2008 to 2010. The presence of a large semidiurnal component in the ion drift variation at the equator produced significant differences from typical ionospheric conditions. Instead of upward …
Sensitivity Analysis Of Empirical Parameters In The Ionosphere-Plasmasphere Model, Janelle V. Jenniges
Sensitivity Analysis Of Empirical Parameters In The Ionosphere-Plasmasphere Model, Janelle V. Jenniges
Janelle V Jenniges
A sensitivity analysis of empirical parameters used in physics-based models was completed in this study to determine their effect on electron densities and total electron content (TEC) in the ionosphere. The model used was the Ionosphere- Plasmasphere Model (IPM) developed by Utah State University. The empirical pa- rameters studied include the O+/O collision frequency, zonal wind, secondary electron production, nighttime E⃗ × B⃗ drifts, and tidal structure. The sensitivity analysis was completed by comparing a default run of the IPM to a run with the parameter ad- justed for three geophysical cases. Many of the comparisons resulted in nonlinear changes …
Duskside F-Region Dynamo Currents: Itsrelationship With Prereversal Enhancement Of Vertical Plasma Drift, P. Park, H. Luhr, Bela G. Fejer, K. W. Mim
Duskside F-Region Dynamo Currents: Itsrelationship With Prereversal Enhancement Of Vertical Plasma Drift, P. Park, H. Luhr, Bela G. Fejer, K. W. Mim
Bela G. Fejer
From magnetic field observations by CHAMP we estimate F-region dynamo current densities near the sunset terminator during solar maximum years from 2001 to 2002. The dynamo currents are compared with the pre-reversal enhancement (PRE) of vertical plasma drift as observed by ROCSAT-1. The seasonal-longitudinal variation of PRE can be largely related to the F-region dynamo current density, with the correlation coefficient reaching 0.74. The correlation can be further improved if we consider a zonal gradient of the E-region Pedersen conductivity, which also depends on season and longitude. It is widely accepted that the Fregion dynamo drives PRE near sunset. For …
Lunar Dependent Equatorial Ionospheric Effects During Sudden Stratosphericwarmings, Bela G. Fejer, M. E. Olson, J. L. Chau, C. Stolle, H. Luhr, L. P. Goncharenko, K. Yumoto, T. Nagatsuma
Lunar Dependent Equatorial Ionospheric Effects During Sudden Stratosphericwarmings, Bela G. Fejer, M. E. Olson, J. L. Chau, C. Stolle, H. Luhr, L. P. Goncharenko, K. Yumoto, T. Nagatsuma
Bela G. Fejer
[1] We have used plasma drift and magnetic field measurements during the 2001–2009 December solstices to study, for the first time, the longitudinal dependence of equatorial ionospheric electrodynamic perturbations during sudden stratospheric warmings. Jicamarca radar measurements during these events show large dayside downward drift (westward electric field) perturbations followed by large morning upward and afternoon downward drifts that systematically shift to later local times. Ground-based magnetometer measurements in the American, Indian, and Pacific equatorial regions show strongly enhanced electrojet currents in the morning sector and large reversed currents (i.e., counterelectrojets) in the afternoon sector with onsets near new and full …
Overviewand Summary Of The Spread F Experiment (Spreadfex), D. C. Fritts, M. A. Abdu, B. R. Batista, I. S. Batista, P. P. Batista, R. Buritii, B. R. Clemesha, J. Comberiate, T. Dautermann, E. De Paula, B. J. Fechine, Bela G. Fejer, D. Gobbi, J. Haase, F. Kalamabadi, B. Laughman, P. P. Lima, H. L. Liu, A. Medeiros, D. Pautet, F. Sao Sabbas, J. H.A. Sobral, P. Stamus, H. Takahashi, M. J. Taylor, S. L. Vadas, C. Wrasse
Overviewand Summary Of The Spread F Experiment (Spreadfex), D. C. Fritts, M. A. Abdu, B. R. Batista, I. S. Batista, P. P. Batista, R. Buritii, B. R. Clemesha, J. Comberiate, T. Dautermann, E. De Paula, B. J. Fechine, Bela G. Fejer, D. Gobbi, J. Haase, F. Kalamabadi, B. Laughman, P. P. Lima, H. L. Liu, A. Medeiros, D. Pautet, F. Sao Sabbas, J. H.A. Sobral, P. Stamus, H. Takahashi, M. J. Taylor, S. L. Vadas, C. Wrasse
Bela G. Fejer
We provide here an overview of, and a summary of results arising from, an extensive experimental campaign (the Spread F Experiment, or SpreadFEx) performed from September to November 2005, with primary measurements in Brazil. The motivation was to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability (RTI) and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures …
Relation Between The Occurrence Rate Of Esf And The Verticalplasma Drift Velocity At Sunset Derived Form Global Observations, C. Stolle, H. Luhr, Bela G. Fejer
Relation Between The Occurrence Rate Of Esf And The Verticalplasma Drift Velocity At Sunset Derived Form Global Observations, C. Stolle, H. Luhr, Bela G. Fejer
Bela G. Fejer
In this study, we investigate two global climatological data sets; the occurrence rate of Equatorial Spread- F (ESF), associated with equatorial plasma irregularities, at 400 km altitude obtained from CHAMP observations, and the evening equatorial vertical plasma drift, vz, from ROCSAT-1 measurements. First, as retrieved for a solar flux level of F10.7=150, the longitudinal variation of the two independently derived quantities correlates between 84% and 93% in the seasons December solstice, equinox and June solstice. The highest correlation is found for the solstice seasons when vz is integrated over local time around the prereversal enhancement (PRE) and displaced 6 towards …
Gravity Wave And Tidalinfluences On Equatorial Spread F Based On Observations During The Spread F Experiment(Spreadfex), D. C. Fritts, S. L. Vadas, D. M. Riggin, M. A. Abdu, I. S. Batista, H. Takahashi, A. Medeiros, F. Kalamabadi, H. L. Liu, Bela G. Fejer, M. J. Taylor, F. Vargas
Gravity Wave And Tidalinfluences On Equatorial Spread F Based On Observations During The Spread F Experiment(Spreadfex), D. C. Fritts, S. L. Vadas, D. M. Riggin, M. A. Abdu, I. S. Batista, H. Takahashi, A. Medeiros, F. Kalamabadi, H. L. Liu, Bela G. Fejer, M. J. Taylor, F. Vargas
Bela G. Fejer
The Spread F Experiment, or SpreadFEx, was performed from September to November 2005 to define the potential role of neutral atmosphere dynamics, primarily gravity waves propagating upward from the lower atmosphere, in seeding equatorial spread F (ESF) and plasma bubbles extending to higher altitudes. A description of the SpreadFEx campaign motivations, goals, instrumentation, and structure, and an overview of the results presented in this special issue, are provided by Fritts et al. (2008a). The various analyses of neutral atmosphere and ionosphere dynamics and structure described in this special issue provide enticing evidence of gravity waves arising from deep convection in …
Equatorial Ionospheric Electric Fields During The November 2004 Magnetic Storm, Bela G. Fejer, J. W. Jensen, T. Kikuchi, M. A. Abdu, J. L. Chau
Equatorial Ionospheric Electric Fields During The November 2004 Magnetic Storm, Bela G. Fejer, J. W. Jensen, T. Kikuchi, M. A. Abdu, J. L. Chau
Bela G. Fejer
[1] We use radar measurements from the Jicamarca Radio Observatory, magnetometer observations from the Pacific sector and ionosonde data from Brazil to study equatorial ionospheric electric fields during the November 2004 geomagnetic storm. Our data show very large eastward and westward daytime electrojet current perturbations with lifetimes of about an hour (indicative of undershielding and overshielding prompt penetration electric fields) in the Pacific equatorial region during the November 7 main phase of the storm, when the southward IMF, the solar wind and reconnection electric fields, and the polar cap potential drops had very large and nearly steady values. This result …
Evolution Of Equatorial Ionospheric Bubbles During A Large Auroral Electrojet Increase In The Recovery Phase Of A Magnetic Storm, M. J. Keskinen, S. L. Ossakow, Bela G. Fejer, J. Emmert
Evolution Of Equatorial Ionospheric Bubbles During A Large Auroral Electrojet Increase In The Recovery Phase Of A Magnetic Storm, M. J. Keskinen, S. L. Ossakow, Bela G. Fejer, J. Emmert
Bela G. Fejer
[1] We present a model and observations of the evolution of equatorial ionospheric bubbles during a large auroral electrojet (AE) index increase in the recovery phase of a geomagnetic storm. Using a three-dimensional time-dependent numerical simulation model, we find, for the 19–21 October 1998 storm, that the equatorial bubble evolution is different during storm time as compared to quiet time conditions. We have found that the storm time vertical drift in conjunction with reduced off-equatorial E region shorting is the primary mechanism that distinguishes the large AE increase recovery phase storm time evolution from the quiet time case. Comparison of …
Assimilative Modeling Of The Equatorial Ionosphere For Scintillation Forecasting: Modeling With Vertical Drifts, J. M. Retterer, D. T. Decker, W. S. Borer, R. E. Daniell, Bela G. Fejer
Assimilative Modeling Of The Equatorial Ionosphere For Scintillation Forecasting: Modeling With Vertical Drifts, J. M. Retterer, D. T. Decker, W. S. Borer, R. E. Daniell, Bela G. Fejer
Bela G. Fejer
[1] Knowledge of the vertical plasma drift velocity observed by the Jicamarca incoherent radar in seven events is assimilated into a theoretical model for the ambient F region plasma density. Comparisons of the calculated plasma density model and the observed plasma density show that, apart from the signature effects of equatorial plasma bubbles, the ambient model captures much of the detail of the plasma density profiles. Rayleigh-Taylor growth rates calculated with the ambient model show a good correlation with the occurrence of spread F.
Global Dayside Ionospheric Uplift And Enhancements Due To Interplanetary Shock Electric Fields, B. R. Tsurutani, A. Mannucci, B. Ijima, A. Saito, K. Yumoto, M. A. Abdu, J. H.A. Sobral, W. D. Gonzalez, F. L. Guarnieri, T. Tsuda, Bela G. Fejer, T. J. Fuller-Rowell, J. U.O. Kozyra, J. C. Foster, A. Coster, V. M. Vasyliumas
Global Dayside Ionospheric Uplift And Enhancements Due To Interplanetary Shock Electric Fields, B. R. Tsurutani, A. Mannucci, B. Ijima, A. Saito, K. Yumoto, M. A. Abdu, J. H.A. Sobral, W. D. Gonzalez, F. L. Guarnieri, T. Tsuda, Bela G. Fejer, T. J. Fuller-Rowell, J. U.O. Kozyra, J. C. Foster, A. Coster, V. M. Vasyliumas
Bela G. Fejer
[1] 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 …
Low Latitude Ionospheric Disturbance Electric Field Effects Duringthe Recovery Phase Of The October 19-21, 1998 Magnetic Storm, Bela G. Fejer, J. T. Emmert
Low Latitude Ionospheric Disturbance Electric Field Effects Duringthe Recovery Phase Of The October 19-21, 1998 Magnetic Storm, Bela G. Fejer, J. T. Emmert
Bela G. Fejer
[1] Low-latitude ionospheric electric fields and currents are often strongly disturbed during periods of enhanced geomagnetic activity. These perturbations can last for several hours after geomagnetic quieting. We use incoherent scatter radar measurements from Jicamarca and Arecibo during 19–21 October 1998 to study, for the first time, the low-latitude disturbance electric fields during the recovery phase of a large magnetic storm. On 19 October the Jicamarca data showed initially large and short-lived (time scale of about 10–20 min) upward and westward drift perturbations in the early afternoon sector, due to the penetration of strong magnetospheric electric fields probably driven by …
Three-Dimensional Nonlinear Evolution Ofequatorial Ionospheric Spread-F Bubbles, M. J. Keskinen, S. L. Ossakow, Bela G. Fejer
Three-Dimensional Nonlinear Evolution Ofequatorial Ionospheric Spread-F Bubbles, M. J. Keskinen, S. L. Ossakow, Bela G. Fejer
Bela G. Fejer
[1] Using numerical simulation techniques, we present the first study of the three-dimensional nonlinear evolution of an equatorial spread-F bubble. The background ionosphere used to initialize the bubble evolution is computed using a time-dependent first-principles equatorial plasma fountain model together with a prereversal enhancement vertical drift model. We find that finite parallel conductivity effects slow down both the linear and nonlinear bubble evolution compared to the two-dimensional evolution. In addition we find that bubble-like structures with extremely sharp density gradients can be generated off the equator at equatorial anomaly latitudes in agreement with recent observations.
Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto
Radar Studies Of Mid-Latitude Ionospheric Plasma Drifts, L. Scherliess, Bela G. Fejer, J. Holt, L. Goncharenko, C. Armory-Mazaudier, M. J. Buonsanto
Bela G. Fejer
We use incoherent scatter radar measurements from Millstone Hill and Saint Santin to study the midlatitude F region electrodynamic plasma drifts during geomagnetically quiet and active periods. We present initially a local time, season, and solar flux dependent analytical model of the quiet time zonal and meridional E × B drifts over these stations. We discuss, for the first time, the Saint Santin drift patterns during solar maximum. We have used these quiet time models to extract the geomagnetic perturbation drifts which were modeled as a function of the time history of the auroral electrojet indices. Our results illustrate the …
Seasonal And Magnetic Activity Variations Of Ionospheric Electric Fields Above The Southernmid-Latitude Station, Bundoora, Australia, M. L. Parkinson, R. Polglase, Bela G. Fejer, L. Scherliess, P. L. Dyson, S. M. Ujmaia
Seasonal And Magnetic Activity Variations Of Ionospheric Electric Fields Above The Southernmid-Latitude Station, Bundoora, Australia, M. L. Parkinson, R. Polglase, Bela G. Fejer, L. Scherliess, P. L. Dyson, S. M. Ujmaia
Bela G. Fejer
We investigate the seasonal, local solar time, and geomagnetic activity variations of the average Doppler velocity measured by an HF digital ionosonde deployed at Bundoora, Australia. The Doppler velocities were heavily averaged to suppress the short-term effects (<3>hours) of atmospheric gravity waves, and thereby obtain the diurnal variations attributed to the tidally-driven ionospheric dynamo and electric fields generated by magnetic disturbances. The observed seasonal variations in Doppler velocity were probably controlled by variations in the lower thermospheric winds and ionospheric conductivity above Bundoora and in the magnetically conjugate location. The diurnal variations of the meridional (fieldperpendicular) drifts and their …
De-2 Observations Of Morningside And Eveningside Plasma Density Depletions In The Equatorial Ionosphere, M. Palmroth, H. Laakso, Bela G. Fejer, R. F. Pfaff
De-2 Observations Of Morningside And Eveningside Plasma Density Depletions In The Equatorial Ionosphere, M. Palmroth, H. Laakso, Bela G. Fejer, R. F. Pfaff
Bela G. Fejer
The occurrence of equatorial density depletions in the nightside F region ionosphere has been investigated by using observations gathered by the polar-orbiting Dynamics Explorer 2 satellite from August 1981 to February 1983. A variety of electric field/plasma drift patterns were observed within these depletions, including updrafting, downdrafting, bifurcating, converging, subsonic, and supersonic flows. The depletions, 116 events in total, are distributed over two groups: group I (eveningside depletions) consists of the events in the 1900–2300 MLT sector, and group II (morningside depletions) are the events in the 2300–0600 MLT sector. A statistical analysis reveals clear differences in the density depletion …
Mid- And Low-Latitude Prompt-Penetration Ionospheric Zonalplasma Drifts, Bela G. Fejer, L. Scherliess
Mid- And Low-Latitude Prompt-Penetration Ionospheric Zonalplasma Drifts, Bela G. Fejer, L. Scherliess
Bela G. Fejer
We have used ion drift observations from the DE-2 satellite to determine the latitudinal variation and the temporal evolution of mid- and low-latitude prompt penetration zonal plasma drifts driven by magnetospheric electric fields. Our results indicate that sudden increases in convection lead to predominantly westward perturbation drifts which decrease equartorwards and have largest amplitudes in the dusk-midnight sector. The diurnal perturbation drift patterns shift to later local times with increasing storm time and decay to new quasi-equilibrium values in about 2 hours, as the ring current readjusts to the new polar cap potential. The daily and latitudinal variations and temporal …
Satellite Studies Of Mid- And Low-Latitude Ionospheric Disturbancezonal Plasma Drifts, L. Scherliess, Bela G. Fejer
Satellite Studies Of Mid- And Low-Latitude Ionospheric Disturbancezonal Plasma Drifts, L. Scherliess, Bela G. Fejer
Bela G. Fejer
We use low- and mid-latitude zonal ion drift observations from the DE-2 satellite and auroral electrojet indices to study the temporal and latitudinal variations of F-region perturbation drifts during magnetically disturbed conditions. These perturbation drifts are driven by magnetospheric and ionospheric disturbance dynamo electric fields with time constants from less than one to several hours. We determine, initially, the drift patterns due to the prompt penetration of magnetospheric electric fields and of longer lasting disturbances. In this study, we concentrate on the properties of the longer lasting perturbations which occur with latitude-dependent time delays after enhancements in the high-latitude ionospheric …
Time Dependent Response Of Equatorial Ionospheric Electric Fieldsto Magnetospheric Disturbances, Bela G. Fejer, L. Scherliess
Time Dependent Response Of Equatorial Ionospheric Electric Fieldsto Magnetospheric Disturbances, Bela G. Fejer, L. Scherliess
Bela G. Fejer
We use extensive radar measurements of F region vertical plasma drifts and auroral electrojet indices to determine the storm time dependence of equatorial zonal electric fields. These disturbance drifts result from the prompt penetration of high latitude electric fields and from the dynamo action of storm time winds which produce largest perturbations a few hours after the onset of magnetic activity. The signatures of the equatorial disturbance electric fields change significantly depending on the relative contributions of these two components. The prompt electric field responses, with lifetimes of about one hour, are in excellent agreement with results from global convection …
Global Equatorial Ionosphericvertical Plasma Drifts Measured By The Ae-E Satellite, Bela G. Fejer, E. R. De Paula, R. A. Heelis, W. B. Hanson
Global Equatorial Ionosphericvertical Plasma Drifts Measured By The Ae-E Satellite, Bela G. Fejer, E. R. De Paula, R. A. Heelis, W. B. Hanson
Bela G. Fejer
Ion drift meter observations from the Atmosphere Explorer E satellite during the period of January 1977 to December 1979 are used to study the dependence of equatorial (dip latitudes ≤ 7.5°) F region vertical plasma drifts (east-west electric fields) on solar activity, season, and longitude. The satellite-observed ion drifts show large day-to-day and seasonal variations. Solar cycle effects are most pronounced near the dusk sector with a large increase of the prereversal velocity enhancement from solar minimum to maximum. The diurnal, seasonal, and solar cycle dependence of the longitudinally averaged drifts are consistent with results from the Jicamarca radar except …
Ion Composition Of The Topside Equatorial Ionosphere During Solar Minimum, S. A. Gonzales, Bela G. Fejer, R. A. Heelis, W. B. Hanson
Ion Composition Of The Topside Equatorial Ionosphere During Solar Minimum, S. A. Gonzales, Bela G. Fejer, R. A. Heelis, W. B. Hanson
Bela G. Fejer
We have used observations from both the Bennett ion mass spectrometer and the retarding potential analyzer on board the Atmosphere Explorer E satellite to study the longitudinally averaged O+, H+, and He+ concentrations from 150 to 1100 km in the equatorial ionosphere during the 1975–1976 solar minimum. Our results suggest that the ion mass spectrometer measurements need to be increased by a factor of 2.15 to agree with the densities from the retarding potential analyzer and with ground-based measurements. The peak H+ concentrations are about 2.5×104 cm−3 during the day and 104 cm−3 at night and vary little with season. …
The Prereversal Enhancement Of Thezonal Electric Field In The Equatorial Ionosphere, D. T. Farley, E. Bonelli, Bela G. Fejer, M. F. Larsen
The Prereversal Enhancement Of Thezonal Electric Field In The Equatorial Ionosphere, D. T. Farley, E. Bonelli, Bela G. Fejer, M. F. Larsen
Bela G. Fejer
The electric fields in the ionospheric E and F regions near the magnetic equator often show a strong eastward enhancement shortly after sunset and before the eastward (normally) daytime field reverses to westward. Several theoretical models of the low-latitude fields suggest that this enhancement is caused mainly or entirely by F region winds (the F region dynamo), but some authors have suggested that it could be produced solely by E region tidal winds. We give here additional calculations and arguments in support of the F region source. The enhancement of the eastward field for an eastward F region wind turns …
Directional And Dynamic Variations Ofauroral Power Spectra Related To The Ionospheric Electron Drift Velocity, E. Nielsen, C. I. Haldoupis, Bela G. Fejer, H. M. Ierkic
Directional And Dynamic Variations Ofauroral Power Spectra Related To The Ionospheric Electron Drift Velocity, E. Nielsen, C. I. Haldoupis, Bela G. Fejer, H. M. Ierkic
Bela G. Fejer
Power spectral observations of auroral electron density fluctuations with a scale length of nearly 1 m have been made with the STARE system (Scandinavian twin auroral radar experiment). Simultaneous measurements of the mean radial Doppler velocities were used to derive estimates of the ionospheric electron drift velocity. The data were analyzed to determine the spectral dependence on the magnitude and direction of the electron drift velocity. The two spectral types, characterized as “narrow” and “broad,” were observed simultaneously from the same scattering volume. The width of the broad spectrum (up to about 1200 Hz) can be at least 3 times …
Radar Interferometry: A New Technique For Studyingplasma Turbulence In The Ionosphere, D. T. Farley, H. M. Ierkic, Bela G. Fejer
Radar Interferometry: A New Technique For Studyingplasma Turbulence In The Ionosphere, D. T. Farley, H. M. Ierkic, Bela G. Fejer
Bela G. Fejer
A new radar interferometer technique has been developed and used successfully at the Jicamarca Radio Observatory in Peru to study the strong nighttime plasma turbulence in the equatorial electrojet. The technique represents a major step forward in radar probing of turbulent irregularities such as (but not limited to) those in the electrojet. In many situations it provides far more information than previous Doppler measurements. We form the cross spectrum of the backscattered signals received from approximately overhead on two antennas, separated in this case along an east-west baseline, as well as the individual power spectra. From the phase of the …
An Empirical Model Of Quiet Dayionospheric Electric Fields Of Middle And Low Latitudes, A. D. Richmond, M. Blanc, B. A. Emery, R. H. Wand, Bela G. Fejer, R. F. Woodland, S. Ganguly, P. Amyenc, R. A. Behnke, C. Calderon, J. V. Evans
An Empirical Model Of Quiet Dayionospheric Electric Fields Of Middle And Low Latitudes, A. D. Richmond, M. Blanc, B. A. Emery, R. H. Wand, Bela G. Fejer, R. F. Woodland, S. Ganguly, P. Amyenc, R. A. Behnke, C. Calderon, J. V. Evans
Bela G. Fejer
Seasonally averaged quiet-day F region ionospheric E × B drift observations from the Millstone Hill, St. Santin, Arecibo, and Jicamarca incoherent scatter radars are used to produce a model of the middle and low-latitude electric field for solar minimum conditions. A function similar to an electrostatic potential is fitted to the data to provide model values continuous in latitude, longitude, time of day, and day of the year. This model is intended to serve as a reference standard for applications requiring global knowledge of the mean electric field or requiring information at some location removed from the observing radars. This …
Ionospheric Irregularities, Bela G. Fejer, M. C. Kelley
Ionospheric Irregularities, Bela G. Fejer, M. C. Kelley
Bela G. Fejer
Extensive experimental and theoretical research has been performed in the last decade to study ionospheric irregularities. These studies have shown that plasma instabilities play a major role in the generation of the irregularities. In this work we describe in detail the recent experimental studies of the E and F region irregularities and also the extensive work on plasma instability theories developed to explain them. We also describe both radio wave and spacecraft-borne experimental techniques to allow a common ground for the understanding of the data from ground-based and in situ experiments. To date, theoretical work has been mostly concentrated on …
Radar Studies Of Anomalousvelocity Reversals In The Equatorial Ionosphere, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman
Radar Studies Of Anomalousvelocity Reversals In The Equatorial Ionosphere, Bela G. Fejer, D. T. Farley, B. B. Balsley, R. F. Woodman
Bela G. Fejer
Radar observations made at Jicamarca show that the equatorial electrojet current and the E and F region electric fields can reverse from their normal direction during the day or night and during magnetically quiet or disturbed conditions. The nighttime reversals can only be detected by such radar measurements. The observations support most of the current hypotheses concerning the electrojet plasma instabilities. The rapid reversals sometimes seen during disturbed conditions indicate that high-latitude currents and electric fields associated with substorm activity strongly perturb the dynamo current system at all latitudes.