Long-term trends of MLT region winds over Central Europe

Abstract

Radar measurements of mesosphere/lower thermosphere winds are carried out since several decades, now allowing the detection of long-term trends and to distinguish from long-period oscillations connected with the solar cycle or atmospheric decadal variability. Here we analyse Collm (52°N, 13°E) LF mean winds near 95 km. The analysis of prevailing winds, tidal amplitudes and phases show (1) a decrease of the summer meridional wind. This change is probably due to modifications of gravity wave filtering through the mesospheric summer jet, (2) a tendency for a decrease of semidiurnal tidal amplitudes, connected with a tidal phase shift. This decrease possibly originates from a combination of CO2 increase and ozone decrease, and (3) an increase of the westerly wind in the mesopause region, probably connected with tropospheric circulation variability and anthropogenic climate change. © 2006 Elsevier Ltd. All rights reserved.