Long-term trends, their changes, and interannual variability of Northern Hemisphere midlatitude MLT winds

Piecewise trend analysis is applied to midlatitude mesosphere/lower thermosphere winds over Europe and Canada. In summer, there are similar trends in each time series of prevailing winds. The zonal prevailing winds in winter show partly opposite behavior at different longitudes, which may be explained by a stationary planetary wave (SPW) influence. Differences between Collm (52°N, 15°E) and Obninsk (55°N, 37°E), both in Europe, are correlated with SPW variability at the interannual time scale, and with tropospheric circulation at the decadal time scale. There are also hints that summer zonal prevailing winds are connected with Southern Hemisphere planetary waves at long time scales. The long-term variation of semidiurnal tidal (SDT) amplitudes corresponds with that of the zonal prevailing wind in a sense that several joint breakpoints of trends are visible. Obninsk and Collm SDT amplitudes show, however, an out-of-phase variability on the decadal time scale.

► Midlatitude summer mesopause region radar winds show similar trends.
► Winter winds at different longitudes show signatures of stationary planetary waves.
► Trends of semidiurnal tidal amplitudes differ with longitude.