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Ann. Geophys., 22, 1665-1674, 2004
www.ann-geophys.net/22/1665/2004/
© European Geosciences Union 2004
Observation of periodic fluctuations in electron and ion temperatures at the low-latitude upper ionosphere by SROSS-C2 satellite
S. R. Prabhakaran Nayar1, L. T. Alexander1, V. N. Radhika1, T. John2, P. Subrahmanyam2, P. Chopra2, M. Bahl2, H. K. Maini2, V. Singh2, D. Singh2, and S. C. Garg2
1Department of Physics, University of Kerala, Trivandrum, 695 581, India
2Radio and Atmospheric Science Division, National Physical Laboratory, New Delhi, 100 010, India
Abstract. The electron and ion temperature at the low-latitude ionosphere exhibits a
wide variety of fluctuations. Observations using SROSS-C2 satellite RPA
payload during 1995–2000 provide an excellent opportunity to study the
fluctuations in Te and Ti in the upper ionosphere and to understand the
dynamic processes existing at those altitudes. The spectral analysis of
electron and ion temperatures using Fourier and wavelet techniques reveal the
presence of quasi-periodicities, such as 14-day, 19-day, 27-day, 55-day, 154-day,
180-day, 1-year and 1.3-year periods. The daytime and nighttime values of
Te and Ti exhibit different types of characteristic variations. The
wavelet spectrum presented depicts the temporal evolution the power of each
periodicity present in the daytime and nighttime values of Te and Ti.
The time evolution of electron and ion temperatures are compared with that of
Ap and 10.7cm solar radio flux, to infer the source of temperature
fluctuations at the upper ionosphere.
Key words. Ionosphere (plasma temperature and density)
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