DISTRIBUTIONS OF THE INTENSITY OF ION TEMPERATURE PERTURBATIONS IN THE THERMOSPHERE

The results are presented from the study of vertical, seasonal, and la titudinal variations of ion temperature perturbations in the altitude region 100 - 400 km using measurements at the network of IS radars ove r a multiyear period. The intensities of ion temperature perturbations having periods less than 6 hours are obtained using the least squares fit filtration of tides from the data. The intensities of the perturb ations are maximized in the altitude region 150 - 180 km at low latitu des. At high latitudes the maxima become much smaller. Seasonal and la titudinal variations of the intensity have different structure below a nd above 150 - 180 km. At altitudes below 120 - 130 km the intensity o f the ion temperature perturbations has a maximum in January and a min imum in July at high latitudes, and two maxima (in summer and winter) at low latitudes. Above 150 - 180 km the intensity of ion temperature perturbations has maxima at high and low latitudes in all seasons. The high-latitude maxima can be attributed to the variations of electric fields and particle precipitation and to the atmospheric waves propaga ted from below and generated in the auroral region. The reasons for th e low-latitude maxima of the intensity are not clear enough. A possibl e reason may be the increased generation of internal gravity waves by tides in the equatorial upper atmosphere.