Long-period meteor radar temperature variations over Collm (51°N, 13°E) and Kazan (56°N, 49°E)

We have estimated temperatures from meteor radar measurements using the gradient method and the full width at half maximum method over Kazan (56°N 49°E) and Collm (51°N, 13°E). The time series cover the period 2016–2019. The temperature gradient model is constructed from SABER temperature observations. We demonstrate that annual mean, amplitudes and phases of the annual and semiannual oscillations of the radar temperatures are close to those of the MLS and SABER temperatures. The annual mean temperatures over Kazan and Collm differ non-significantly. The seasonal variability of the radar temperature is mostly due to the annual cycle which tends to grow with latitude. The gradient method produces temperatures which agree with the SABER temperatures better than with the MLS ones. The harmonics of the annual oscillations from periods of 73 days up to periods of about 40 days are the most significant day-to-day temperature oscillations and have zonal wavenumber zero. Their periods and phases are in good correspondence with those of the MLS and SABER ones. We also show some results which demonstrate that at 56°N the FWHM method is not as robust as the gradient method.     

Longitudinal MLT wind structure at higher mid-latitudes as seen by meteor radars at central and Eastern Europe (13°E/49°E)

The mid-latitude mesosphere and lower thermosphere (MLT) wind speeds measured by two SKiYMET meteor radars (MRs) at Collm (51°N, 13°E) and Kazan (56°N, 49°E) during 2016–2017 were analyzed to study longitudinal wind structures. The differences between monthly mean prevailing wind speeds and tidal amplitudes were compared with the corresponding differences obtained from TIMED/TIDI satellite winds and gradient wind speeds from the AURA/MLS instrument. It is shown that the MR wind difference between the two sites is statistically significant. The difference of the horizontal prevailing winds can be explained by a superposition of the background zonal flow, which is different at the two latitudes, with stationary planetary waves of different origin. Non-migrating tides contribute significantly to the difference of the semidiurnal tidal winds between the two sites.