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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
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 …
Simulation Of The Prereversalenhancement In The Low Latitude Vertical Drifts, C. G. Fesen, R. G. Noble, A. D. Richmond, G. Crowley, Bela G. Fejer
Simulation Of The Prereversalenhancement In The Low Latitude Vertical Drifts, C. G. Fesen, R. G. Noble, A. D. Richmond, G. Crowley, Bela G. Fejer
Bela G. Fejer
Low latitude F region ion motions exhibit strong seasonal and solar cycle dependences. The pre-reversal enhancement (PRE) in the vertical ion drifts is a particularly well-known low latitude electrodynamic feature, exhibited as a sharp upward spike in the velocity shortly after local sunset, which remains poorly understood theoretically. The PRE has been successfully simulated for the first time by a general circulation model, the National Center for Atmospheric Research thermosphere/ionosphere/electrodynamic general circulation model (TIEGCM). The TIEGCM reproduces the zonal and vertical plasma drifts for equinox, June, and December for low, medium, and high solar activity. The crucial parameter in the …
An Incoherent Scatter Radar Technique For Determining Two-Dimensional Ionization Structure In Polar Cap F-Region Patches, T. R. Pedersen, Bela G. Fejer, R. A. Doe, E. J. Weber
An Incoherent Scatter Radar Technique For Determining Two-Dimensional Ionization Structure In Polar Cap F-Region Patches, T. R. Pedersen, Bela G. Fejer, R. A. Doe, E. J. Weber
Bela G. Fejer
We present a technique which combines time series of line-of-sight (LOS) velocity and electron density measurements from the Sondrestrom incoherent scatter radar (74.5° invariant latitude) to reconstruct the large-scale horizontal structure of the F region ionosphere during polar cap patch events. This reconstruction technique provides a new density-based means of examining patch morphology. Its wide region of coverage also facilitates comparison of radar measurements with other observational data sets. For two periods when patches were present and convection conditions in the nightside polar cap could be adequately approximated by the simple velocity model used in this initial implementation of the …
Optical Remote Sensing Of The Thermosphere With Heater Induced Artificial Airglow (Hiaa), P. A. Bernhardt, M. Wong, J. D. Huba, Bela G. Fejer, L. S. Wagner, J. A. Goldstein, C. A. Selcher, V. L. Frolov, E. N. Sergeev
Optical Remote Sensing Of The Thermosphere With Heater Induced Artificial Airglow (Hiaa), P. A. Bernhardt, M. Wong, J. D. Huba, Bela G. Fejer, L. S. Wagner, J. A. Goldstein, C. A. Selcher, V. L. Frolov, E. N. Sergeev
Bela G. Fejer
Optical emissions excited by high-power radio waves in the ionosphere can be used to measure a wide variety of parameters in the thermosphere. Powerful high-frequency (HF) radio waves produce energetic electrons in the region where the waves reflect in the F region. These hot or suprathermal electrons collide with atomic oxygen atoms to produce localized regions of metastable O(1D) and O(1S) atoms. These metastables subsequently radiate 630.0 and 557.7 nm, respectively, to produce clouds of HF pumped artificial airglow (HPAA). The shapes of the HPAA clouds are determined by the structure of large-scale (≈10 km) plasma irregularities that occur naturally …
Group Invariant Solutions Without Transversality And The Principle Of Symmetric Criticality, Charles G. Torre
Group Invariant Solutions Without Transversality And The Principle Of Symmetric Criticality, Charles G. Torre
Charles G. Torre
No abstract provided.
Organic Carbon Supply And Metabolism In A Shallow Groundwater Ecosystem, Michelle A. Baker
Organic Carbon Supply And Metabolism In A Shallow Groundwater Ecosystem, Michelle A. Baker
Michelle A. Baker
In groundwater ecosystems, in situ primary production is low, and metabolism depends on organic matter inputs from other regions of the catchment. Heterotrophic metabolism and biogeochemistry in the floodplain groundwater of a headwater catchment (Rio Calaveras, New Mexico, USA) were examined to address the following questions: (1) How do groundwater metabolism and biogeochemistry vary spatially and temporally? (2) What factors influence groundwater metabolism? (3) What is the energy source for groundwater metabolism?
Average Daytime Disturbanceneutral Winds Measured By Uars: Initial Results, Bela G. Fejer, J. T. Emmert, G. G. Shepard, B. H. Solheim
Average Daytime Disturbanceneutral Winds Measured By Uars: Initial Results, Bela G. Fejer, J. T. Emmert, G. G. Shepard, B. H. Solheim
Bela G. Fejer
Thermospheric neutral winds play important roles on the dynamics of the upper atmosphere. We use extensive F region zonal and meridional wind data measured by the Wind Imaging Interferometer (WINDII) instrument on board the Upper Atmosphere Research Satellite (UARS) to study the mid-and low-latitude daytime average perturbation winds during magnetically disturbed periods. We have determined the perturbation winds by subtracting the quiet time wind values along the satellite orbits. Our data indicate large changes in the latitudinal profiles of both the zonal and meridional disturbance winds from morning to afternoon hours. The early morning zonal disturbance winds are eastward near …