Tide induced annual variability of selected physico-chemical characteristics in the northern Bay of Bengal (nBoB) with a Special emphasis on Tropical Cyclone-Phailin, 2013.

Abstract

Daily monitoring (in the day time) of sea surface temperature (SST), sea surface salinity (SSS), pH and weekly measurement of dissolved oxygen (DO) were carried out in the northernmost sector of the Bay of Bengal for the first time, covering roughly an area of ~750 sq. km throughout an annual cycle from 1^st June, 2013 to 31^st May, 2014. SSS, pH and DO maintained a higher and lower value during the highest high tide (HHT) and lowest low tide (LLT) hours respectively, throughout the year, except in some weeks of monsoon. But SST did not follow any such type of tide influence trend. The strong physical forcing and high energy tidal surges caused by the tropical cyclone (Phailin) increased the SSS, pH and DO by 33.11%, 3.73% and 40% respectively. In contrast, a massive cooling in SST by 15.38% was observed. Though SST returned to normal range within one week, DO and SSS took almost 10 days to reach equilibrium. However, tropical cyclone poses a short term strong impact on the physico-chemical properties and ecology of the shallow continental shelf coastal water.