Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4721959 | Physics and Chemistry of the Earth, Parts A/B/C | 2006 | 6 Pages |
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.