A study of the association of surface potential gradient with the onset of monsoon at Pune

Abstract

Simultaneous measurements of fair weather surface potential gradient, vapour pressure, westerly wind (speed and direction), mean sea level pressure, and dry bulb temperature at Pune (18°32 'N, 73°51 'E: 559 m AMSL) during April-June of 1973-77 were analysed and examined for monthly and seasonal variations. The results suggested about 17 and 50% diminution in potential gradient in May and June over the period of study with respect to the values in April and about 50 to 100% increase only in vapour pressure and westerly wind among other meteorological parameters. This was suggestive of their preferential influence to decrease the potential gradient. The study also showed that the year to year lower or higher monthly mean value of potential gradient bore a fairly good correspondence with the early or late onset of monsoon. This was suggestive of about 25% and 10% higher values of potential gradient in April and May than the net average for delay in monsoon by about a week.