CHANGES IN STRATOSPHERIC AND MESOSPHERIC THERMAL CONDITIONS DURING THE LAST 3 DECADES .2. THE EVOLUTION OF ANNUAL AND SEMIANNUAL TEMPERATURE OSCILLATIONS

Estimates of the amplitudes and phases of annual and semiannual temper ature oscillations on 13-year moving intervals of observational series in the height range of 25 to 75 km were derived from monthly mean tem peratures measured by meteorological M-100B rockets at Hayes Island, V olgograd, Tumba, and Molodezhnaya stations from 1964 to 1994. A consid erable increase in the amplitudes of annual and semiannual harmonics w as revealed in the extratropical mesosphere. A great variation in the amplitudes of annual and semiannual temperature oscillations was also found in the stratosphere. The phases of temperature oscillations were mainly unchanged during the entire observational time. The amplitudes of annual stratospheric and mesospheric temperature oscillations rema ined constant over the Tumba tropical station, but their phases change d greatly. The results obtained were compared with reference character istics of the CIRA-86 model.