Zonal prevailing wind trends derived from combined low-frequency and VHF meteor radar wind measurements in the lower thermosphere over Collm (51.3°N, 13.0°E)

Mesopause region winds have been measured by the low-frequency (LF) method at Collm until 2008. Since 2004, meteor radar (MR) measurements have been performed also. The LF and MR data set are combined to obtain a continuous time series of monthly zonal prevailing winds from 1979 through 2013 at about 90 km altitude. It has been found that, on a monthly time scale, the difference between zonal prevailing winds measured by LF and MR are small. During the 35-yr time interval considered, the zonal winds show positive trends towards more westerly winds throughout the year except for spring. There is a tendency that in spring and summer the trends are changing from more positive to small or negative after 1995. There is a possible influence of the 11-year solar cycle, most visible during early summer and early winter, and the effect weakens during recent years