SOLAR-CYCLE DEPENDENCE AND LONG-TERM TRENDS IN THE WIND-FIELD OF THE MESOSPHERE LOWER THERMOSPHERE

Ground-based observations of the wind field in the mesosphere/lower th ermosphere have been used to investigate long-lasting wind variations at mid-latitudes. Besides small solar activity induced variations (11 yr cycle), non-solar induced long-term trends were clearly detected, w hich could be a hint of anthropogenically caused variations in the win d field near the mesopause region. Comparisons with other observations qualitatively confirm the derived trends, thus indicating common long -term global changes of the dynamical state of the middle atmosphere. (C) 1997 Elsevier Science Ltd.