Mean winds observed by the Kunming MF radar in 2008–2010.

We have investigated the variation of mean wind almost continuously monitored by the Kunming (25.6°N, 103.8°E) MF radar over the period from August 2008 to August 2010. The mean circulation in zonal winds presents a obvious annual variation above 90 km and semiannual variation below 85 km, but has different direction up 90 km and down 85 km. An eastward flow is prevailing in spring and autumn below 85 km and in spring and summer up 90 km with amplitudes as large as 24 m/s and 21 m/s, respectively. But a westward flow dominates in summer and winter below 85 km and in autumn and winter up 90 km with amplitudes as large as −12 m/s and −10 m/s, respectively. Meanwhile the eastward wind dominates for all months at 85–90 km. The annual variation also appears in meridional wind below 90 km, which means a poleward flow occurs from September to April with amplitude maximum of 11 m/s, while the equatorward wind dominates almost for two years with maximum of −26 m/s above 90 km. Comparison of the wind vertical profile along with standard errors with the HWM07 model winds shows that the zonal wind agrees well with model in winter, autumn and summer, but the meridional wind in spring, winter and summer. [ABSTRACT FROM AUTHOR]