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Author Ma, Ti-Ze ♦ Schunk, R. W.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PHYSICS ♦ IONOSPHERE ♦ IONIZATION ♦ COUPLING ♦ DISTURBANCES ♦ THERMOSPHERE ♦ POLAR REGIONS
Abstract Polar cap patches are regions of enhanced ionization that appear when the interplanetary magnetic field is southward. They are created either in the dayside cusp or equatorward of the cusp in the sunlit hemisphere. Once formed, they convect in an antisunward direction across the dark polar cap at speeds of 100 m/s. The size of a plasma patch varies from about 100 to 1000 km, and its density relative to the background density varies from a few tens of percent to a factor of 100. Because propagating plasma patches might have a significant effect on the neutral atmosphere, a global thermospheric circulation model was used to calculate the response of the polar thermosphere to a {open_quotes}representative{close_quotes} plasma patch. The model predicts that a localized thermospheric disturbance is characterized by a neutral gas upwelling, and O/N{sub 2} composition changes. The thermospheric disturbance persists for a time that is much longer than the patch lifetime, and it spreads out over a region that is much larger than the patch dimensions as it dissipates. 52 refs., 9 figs., 1 tab.
ISSN 01480227
Educational Use Research
Learning Resource Type Article
Publisher Date 1995-10-01
Publisher Place United States
Journal Journal of Geophysical Research
Volume Number 100
Issue Number A10


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