Abstract

The study deals with determining ionosphere parameter at low latitudes during the maximum of solar cycle 22 on quiet days. It uses Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) to carry out Total Electron Content (TEC) parameter in the ionosphere region. TEC time variability on summer and winter highlights a seasonal anomaly, a phenomenon observed since 1965 and which appears while radiations coming from the sun are more intensive in summer than in winter under low latitudes. A mathematical approach integrating the time values of TEC parameter is developed to calculate TEC total value during all the season. The study shows that the seasonal anomaly phenomenon is not observed at every time between summer and winter. Comparison of the rate of electrons production matches with solar radiation intensity between summer and winter during a short period. Apparition of winter anomaly phenomenon shows that ultraviolet and X-rays emitted from the Sun are not the only causes of ionization of particles in ionosphere. Other chemical or physical phenomena also contribute to enhance the concentration of electrons in the atmosphere. The estimation of the rate of TEC production in ionosphere F2-layer enables a comparison of summer and winter behavior in ionosphere layer. The study offers a good knowledge of winter anomaly phenomenon.

Key words: Total electron content, thermosphere-ionosphere-electrodynamics general circulation model, winter anomaly, maximum of solar cycle, quiet day.