Understanding the Spatial Variability of Chlorophyll a and Total Suspended Matter Distribution Along the Southwest Bay of Bengal Using In-Situ and OCM-2 & MODIS-Aqua Measurements

Spatial and temporal distribution of chlorophyll a (chl a) and Total Suspended Matter (TSM) and inter comparison of Ocean Color Monitor-2 (OCM-2) and Moderate Resolution Imaging Spectro-radiometer (MODIS-Aqua) derived chlorophyll a and TSM was made along the southwest Bay of Bengal (BoB). The in-situ chl a and TSM concentration measured during different seasons were ranged from 0.09 to 10.63 μgl−1 and 11.04–43.75 mgl−1 respectively. OCM-2 and MODIS derived chl a showed the maximum (6–8 μgl−1) at nearshore waters and the minimum (0–1 μgl−1) along the offshore waters. OCM-2 derived TSM imageries showed the maximum (50–60 mgl−1) along the nearshore waters of Palk Strait and the moderate concentration (2–5 mgl−1) was observed in the offshore waters. MODIS derived minimum TSM concentration (13.244 mgl−1) was recorded along the offshore waters, while the maximum concentration of 15.78 mgl−1 was found along the Kodiakarai region. The inter-comparison of OCM-2 and MODIS chl a data (R2 = 0.549, n = 49, p < 0.001, SEE = ±0.117) indicate that MODIS data overestimates chl a concentration in the nearshore waters of the southern BoB compared to the OCM-2. The correlation between OCM-2 and MODIS-Aqua TSM data (R2 = 0.508, N = 53, P < 0.001 and SEE = ±0.024) confirms that variation in the range of values measured by OCM-2 (2–60 mgl−1) and the MODIS (13–16 mgl−1) derived TSM values. Despite problems in range of measurements, persistent cloud cover etc., the launch of satellites like OCM-2 with relatively high spatial resolutions makes job easier and possible to monitor chl a distribution and sediment discharges on day to day basis in the southwest BoB.