Abstract

Particulate Organic Carbon (POC) plays a vital role in ocean carbon cycle and is linked to many important ocean biogeochemical processes. This study aims to investigate the seasonal variability of POC and its association with Sea Surface Temperature (SST), Chlorophyll-a (Chl-a) and wind vector in the Bay of Bengal (BoB) of Bangladesh part, as well as to validate satellite data with in-situ measurement data. Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua satellite level-3 data of POC, Chl-a and SST were used in this study. Wind vector data were obtained from WindSat Polarimetric Radiometer satellite. Monthly averaged POC (2002-2019) was ranged from 103.08 to 184.22 mg m-³ with an average of 154.28±31.47 mg m-3. The POC was higher (181.80 ±22.34 mg m-³) during the northeast-monsoon (December-February), and lower (136.56±36.24 mg m-³) in the pre-monsoon (March-May). Statistically significant (F (3,202) =18.09; p<0.05) difference of POC was found among the seasons. A very weak inverse relationship was found between POC and SST whereas POC and Chl-a showed a positive relation for all the seasons in the BoB. This study revealed that the POC was very prominent with the wind vectors prevailing northeasterly in northeast and post monsoon and low with the southwesterly wind in southwest and pre monsoon. POC variability was mostly influenced by Chl-a than SST and wind vector for BoB. Variability of POC in BoB is mainly influenced by monsoon effect which causes tremendous rainfall and strong wind. A significant (p<0.05) moderate correlation (r=0.74) was found between the MODIS Aqua satellite data and in-situ observation. Further detailed investigation is required to observe the association of other parameters with POC variability.