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A Modeling Study of the Latitudinal Variations in the Nighttime Plasma Temperatures of the Equatorial Topside Ionosphere During Northern Winter at Solar MaximumLatitudinal 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.
Document ID
20010019273
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Bailey, G. J.
(Sheffield Univ. United Kingdom)
Denton, M. H.
(Sheffield Univ. United Kingdom)
Heelis, R. A.
(Texas Univ. at Dallas Richardson, TX United States)
Venkatraman, S.
(Texas Univ. at Dallas Richardson, TX United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2000
Publication Information
Publication: Annales Geophysicae
Publisher: Springer-Verlag
Volume: 18
Subject Category
Geophysics
Funding Number(s)
CONTRACT_GRANT: NAG5-4456
CONTRACT_GRANT: PPARC-PPA/G/O/1997/00691
CONTRACT_GRANT: NSF ATM-96-15064
Distribution Limits
Public
Copyright
Other

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