On the periodicities in the tropospheric wind flow during the northeast monsoon season

Abstract

Several attempts were made ill the past to track the disturbances that affect the weather over south Peninsula during the northeast monsoon season. But these had limited success mainly because of the lack of data over the oceans, Thus-conventional synoptic analysis has its limitations in tracking these disturbances across the, Bay of Bengal. Therefore to determine the periodic nature of these disturbances, the upper wind data of a few stations south of 15 N have been subjected to power spectrum analysis after applying suitable high pass filter.

The results indicate the existence of dominant periodicity of a week to about 10 days. Relatively weak waves of period around 4-5 days are also noticed. The periodicities are generally more marked in the zonal flow than in the medicinal flow. The periodic nature of waves shows some variations from one northeast monsoon season to the other.