Study of the Signature of Solar Activity in Periodic Fluctuations Observed in Electron and ion Temperature at the Low Latitude Ionosphere.
Lalitha T. Alexander, Nayfa Suliman Muhammed Al Atawi, Hala M. Abu Mostafa, George T. John

Abstract
The electron and ion temperatures at the upper ionosphere depends on both solar and terrestrial conditions and is found to exhibit a variety of periodic variations found in solar and terrestrial parameters like diurnal, seasonal, latitudinal and solar activity associated. Periodic fluctuations in the geomagnetic activity and ionospheric fluctuations result from the intrinsic state of the Sun, relative orientation of Earth with respect to the Sun and processes at the earth. Mainly Sun provides the driving force for all geomagnetic and ionospheric fluctuations. Observations usingSROSS-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 process existing at all these altitudes. The spectral analysis of electron and ion temperatures using Fourier and wavelets technique reveal the presence of quasi periodicities such as 14-day, 18-day, 27-day, 55-day and 154-day, 180- day, 1- year and 1.3 – year periods. The study of the characteristics of the Fourier and wavelet spectrum helps to infer prominent processes are associated with the heating of the upper ionosphere. The day time and night time values of Te and Ti exhibit different types of characteristic variations. The wavelet spectrum explains the temporal evolution of the power of each periodicity present in the day time and night time values. The time evolutions of electron and ion temperatures are compared with that of Ap index and 10.7 cm solar radio flux.

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