POSSIBLE SECULAR CHANGE AND LAND-TO-OCEAN EXTENSION OF AIR-POLLUTION FROM MEASUREMENTS OF ATMOSPHERIC ELECTRICAL-CONDUCTIVITY OVER THE BAY OF BENGAL

Diurnal variations of the atmospheric electrical conductivity and elec tric field at a fixed point in the Bay of Bengal, where an oceanograph ic ship, ORV Sagarkanya, remained stationary for a total of 28 days, a re reported. From observations, one can speculate a secular decrease i n total conductivity in the Bay of Bengal by at least 40% since the Co bb and Wells (1970) measurements during 1967 global expedition. Proble m of the land-to-ocean extension of air pollution has been studied fro m the conductivity measurements made in the monsoon season when surfac e winds are persistently southwesterly. Values of conductivity near th e eastern coastline of India where windflow is from land to sea are ab out half of those near to the western coastline where windflow is from sea to land. It is concluded that to know the air conductivity at a p oint over sea, the age of air mass over sea is a better determining fa ctor than the distance from the coastline.