Simultaneous observation of quasi 16 day wave in the mesospheric winds and temperature over low latitudes with the SKiYMET radar

摘要

The seasonal characteristics of a 16 day planetary wave simultaneously in mesospheric temperature and winds over a low-latitude station Thumba (8.5°N, 76.5°E) using meteor radar observations are discussed for the first time. Four years (2005–2008) of meteor radar winds and temperature observations are used for the present study. It is observed that the amplitude of a 16 day wave in zonal component is more than that of meridional. Further analysis shows that the westerly phase of zonal wind is more favorable for the 16 day waves. The maximum amplitude of a 16 day wave in mesospheric temperature is observed during January–February and August–September. Climatology of a 16 day wave shows the signature of semiannual oscillation (SAO) in mesospheric temperature but not in winds. The vertical amplitude structure of zonal component shows the maximum amplitude at ∼88–92 km with constant phase. It is also noticed that zonal and meridional winds are in phase, whereas the temperature leads zonal wind by 5 ± 1 days. The significance of the present study lies in showing the 16 day wave characteristics, effect of background winds, and manifestation of SAO on their variability.