Open AccessDistinctive plasma density features of the topside ionosphere and their electrodynamics investigated during southern winter
Author(s) -
Horvath Ildiko,
Lovell Brian C.
Publication year - 2009
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008ja013683
Subject(s) - trough (economics) , ionosphere , earth's magnetic field , f region , polar , ion , plasma , geology , physics , geophysics , atmospheric sciences , latitude , defense meteorological satellite program , electron density , south atlantic anomaly , northern hemisphere , magnetic field , magnetosphere , geodesy , astronomy , van allen radiation belt , quantum mechanics , economics , macroeconomics
This study utilizes a novel technique to map the Defense Meteorological Satellite Program (DMSP) data across the two hemispheres to learn about the morphology and plasma composition of the topside ionosphere, and the underlying ionospheric dynamics. In the southern winter hemisphere, the regional maps tracked a heavy‐ion (Ni‐O + ) trough, aurora zone, polar hole, and large plasma density depletion. The latter appeared in the region of the South Atlantic Magnetic Anomaly (SAMA). The electron temperature (Te) map detected the thermal characteristics of these features, while the plasma drifts and flux maps tracked their dynamics. Results show that there were special electrodynamic effects in the SAMA region due to the low magnetic field and high conductivity. These increased the vertical downward (V Z ) and the westward (V Y ) drifts. Independently, the V Z and V Y maps registered the affected area that was depleted in heavy ions and rich in light ions. Some field‐aligned profiles tracked the impact of these SAMA effects on the heavy‐ion trough, which was a stagnation trough and appeared markedly differently at different longitudes. At trough latitudes ((56 ± 4)°S (geomagnetic) when Dst av = 0 nT), the elevated electron temperatures forming a Te peak indicated subauroral heating effects. A statistical study modeled the magnetic activity dependence of the Te peak's magnitude and location and revealed their linear correlation with the activity level. Statistically, the Te peak increased [10.226 ± 1.355]°K and moved equatorward [0.051 ± 0.009]° (geomagnetic) per 1 nT decrease in the averaged Dst index. Per 1 nT increase in the averaged AE index, its magnitude increased [1.315 ± 0.444]°K and the equatorward movement was [0.014 ± 0.003]°.