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 electric field at a fixed point in the Bay of Bengal, where an oceanographic ship, ORV Sagarkanya, remained stationary for a total of 28 days, are reported. From observations, one can speculate a secular decrease in total conductivity in the Bay of Bengal by at least 40% since the Cobb and Wells (1970) measurements during 1967 global expedition. Problem of the land-to-ocean extension of air pollution has been studied from the conductivity measurements made in the monsoon season when surface winds are persistently southwesterly. Values of conductivity near the eastern coastline of India where windflow is from land to sea are about 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 point over sea, the age of air mass over sea is a better determining factor than the distance from the coastline.