Variations in mesospheric temperature during polar mesospheric summer echoes.

The behavior of the ordinary radio wave amplitude at the frequency of 2.66 MHz of the partial reflection radar of the Polar Geophysical Institute (Tumanny observatory, Murmansk region, 69.0N, 35.7E) during the appearance of the polar mesospheric summer echoes on August 15, 2015 was considered. Using of radio physical method from the spectra of the amplitude at different heights the mesospheric temperature profile was calculated for the considered data. Significant reductionof temperature values near the heights of the mesopause corresponded to sharp changes in the amplitude spectra of the ordinary wave.

Climatologies of mean winds and tides observed by medium frequency radars at Tromsø (70°N) and Saskatoon (52°N) during 1987–1989

A real-time winds system from Saskatoon has operated with the Tromsø medium frequency (MF) (partial reflection) radar (70°N, 20°E) since mid-1987. Although the system has a poorer data yield than usual, owing to smaller receiving antennas, it has proven possible over 2 years to obtain 12 month climatologies of mean winds and tides (70–75 to 100 km) with a 10 d resolution. These are compared with similar products from the Saskatoon MF radar (52°N, 107°W). The mean winds and tides generally show similar seasonal morphologies. However the mean winds are weaker, consistent with smaller meridional temperature gradients. Also, there are significant changes in the tidal wavelengths and amplitudes suggesting that considerable adjustments of modal composition have occurred. The tides are compared with recent numerical-theoretical models.