A THEORY OF THERMOSPHERIC DYNAMICS .I. DIURNAL AND SOLAR CYCLE VARIATIONS

It is shown that the diurnal density and temperature variation within the thermosphere is generated not only by solar EUV heat input but also by a tidal wave from the lower atmosphere which penetrates into the thermosphere and predominates the diurnal variations below 250 km altitude. Assuming a tidal wave from below which is not dependent on solar activity and assuming solar EUV heat input to be proportional to the solar activity factor F10·7, the observed diurnal density variation and its dependence on solar activity can be explained and reproduced quantitatively with help of a two dimensional model between 100 and 400 km height. The calculated density agrees with the Jacchia model above 300 km and with observations made by Priester, May, King-Hele, Taeusch and by Marov below 250 km. © 1969.