Short-period variations of ionospheric drifts at Collm an their connection with the dynamics of the lower and middle atmosphere

Abstract

Studies of the intensity of horizontal drift velocity perturbations with periods 0.7 – 3 hours at the altitudes 80 – 110 km are made from the data of regular low-frequency D1 ionospheric reflection observations at Collm, Germany (52° N, 15° E) in 1983 – 1999. Seasonal changes of variances of short-period perturbations of zonal velocity reveal the main maximum in summer and a smaller maximum in winter near the altitude 80 km and the two maxim at equinoxes near and above 100 km. Perturbation variances had the minima in 1985 -- 1987 and in 1996 -- 1998. Numerical modeling shows that IGW's generated in the strato-mesospheric jet stream may have substantial amplitudes at altitudes near and above 100 km and may modify seasonal variations of tropospheric IGWs.