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The altitude dependence of the local time variation of thermospheric density
Author(s) -
Sharp L. R.,
Hickman D. R.,
Rice C. J.,
Straus J. M.
Publication year - 1978
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl005i004p00261
Subject(s) - thermosphere , atmospheric sciences , equator , altitude (triangle) , latitude , ionosphere , local time , environmental science , satellite , atmospheric models , longitude , mesosphere , variation (astronomy) , climatology , geology , physics , stratosphere , geophysics , geodesy , astrophysics , statistics , geometry , mathematics , astronomy
Analysis of density measurements from the AE‐E satellite have demonstrated that the local time variation in the thermosphere at low latitudes (<20°) changes from predominantly diurnal at high altitudes (∼300 km) to predominantly semidiurnal at low altitudes (∼140 km). This behavior is significant because it both affects the accuracy of density predictions at low satellite altitudes and confirms that the mesospheric semidiurnal tide is important to the dynamics of the lower thermosphere. Comparison of the results with the local time dependence found in the thermospheric model of Jacchia (1971) and the MSIS model of Hedin et al . (1977a and b) indicate that only the latter correctly models the transition to dominantly semidiurnal behavior at lower thermospheric altitudes near the equator.