Variation of water column density in the Bay of Bengal aquatic ecosystem

Abstract

Water column stratification is very important to investigate the ocean dynamics. For this study, the Bay of Bengal was divided into some sub-regions and division wise temperature and salinity data were taken to study the distribution of water column density comprehensively from Argo profiling floats for the period January 2009 to December 2013. To understand the processes affecting the sigma-t variability, we also examined static stability parameters for the same region. In winter, temperature profiles of regions 1, 2 and 3 were showed a distinct thermal inversion. It may occur due to maximum net heat loss. In spring, the basin averaged temperature profile were showed no thermal inversion. Salinity was increased sharply from 25m to 85m. During spring temperature remained same, but a decrease was observed in salinity (0.5 psu) and sigma-t (0.2 kg m-3). Considering all regions, salinity was increased sharply from 15m to 65m whereas salinity at 5m was 33.1 psu, during summer. During fall season, Along the southern bay from west (Region-7) to east (Region 9) a decrease in temperature (0.3 °C), salinity (0.3 psu) and sigma-t (0.1 kg m-3) occurred. In winter and spring, southern bay stability was stronger than northern. In summer and fall, northern bay stability was stronger than southern and also highest compared to other season. Ship cruise CTD data can be collected for further study.