Fluctuations in the pattern of distribution of SW monsoon rainfall over Rajasthan and their association with sunspot cycle

Abstract

The yearly pattern of distribution of rainfall during the SW monsoon season for each of the years 1901 to 1950 for stations over Rajasthan are represented by six derived parameters. Year to year variation of these parameters, describing the distribution of monsoon rainfall, has been studied for nine representative stations over Rajasthan.

       Polynomial trend analysis of the time series of parameters indicate oscillatory features and power spectrum analysis reveal certain significant periods corresponding to sunspot cycle or quasi- iennial oscillation, On examination of the monsoon circulation features such as the surface pressure anomalies and frequency of breaks in monsoon over India suggest that breaks in the monsoon are more during sunspot maximum than during sunspot minimum. It is also, observed that frequency of storms and depression is less during sunspot maximum than during the sunspot mimmum.