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Ann. Geophys., 20, 807-815, 2002
www.ann-geophys.net/20/807/2002/
© European Geosciences Union 2002
Diurnal, seasonal and latitudinal variations of electron temperature measured by the SROSS C2 satellite at 500 km altitude and comparison with the IRI
P. K. Bhuyan1, M. Chamua2, P. Subrahmanyam2, and S. C. Garg2
1Department of Physics, Dibrugarh University, Dibrugarh 786 004, India
2Radio and Atmospheric Science Division, National Physical Laboratory, New Dehli 110 012, India
Correspondence to: P. K. Bhuyan (bhuyan@dibru.ernet.in)
Abstract. The
diurnal, seasonal and latitudinal variations of electron
temperature Te,
measured by the SROSS C2 satellite at
equatorial and the low-latitudes during the low solar activity
period of 1995–1997 are investigated. The average height
of the satellite was ~ 500
km and it covered the latitude belt of –31°
to 34° and the
longitude range of 40°–100°. Te
varies between 700–800 K during
night-time (20:00–04:00 LT), rises
sharply during sunrise (04:00–06:00 LT) to reach a level of ~
3500 K within a couple of hours
and then falls between 07:00–10:00 LT to a daytime average
value of ~ 1600
K. A secondary maximum is observed around
16:00–18:00 LT in summer. Latitudinal gradients in
Te have
been observed during the morning enhancement and
daytime hours. Comparison of measured and International Reference
Ionosphere (IRI) predicted electron temperature reveals
that the IRI predicts nighttime Te well
within ~ 100 K of
observation, but at other local times, the predicted Te
is less than that measured in all seasons.
Key words. Ionosphere,
equatorial ionosphere, plasma temperature, and
density
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