Temporal Scales of Satellite-Derived Atmospheric Winds Over the Asian Monsoon Region

The autocorrelation function of Meteosat-7-derived atmospheric motion vectors (AMVs) has been calculated over the Indian Ocean region for the Asian summer and winter monsoon seasons. The time where the autocorrelation function dropped to 0.5 was defined as the decorrelation time. It was observed that seasonal forcing caused the circulation patterns to be highly stable with decorrelation timescales on the order of 24 h or more at some regions. The analysis was done for the vector wind (u + iv), the zonal component u, and the meridional component v. The nature of the autocorrelation function clearly followed the changing wind circulations with season and pressure levels.