Biophysical Processes

We observe physical parameters of ocean like temperature and salinity, and biological parameters like chlorophyll, along with other deduced parameters like density or Brunt Vaisala frequency. Specific important areas/phenomena are selected and their variability is studied in inter-annual/seasonal/diurnal scale. We try to explain our observations by further statistics and analysis.

The Agulhas Return Current (ARC) is one of the current systems in the Southern Indian Ocean (SIO) associated with high Chlorophyll-a Concentrations (CC). This work presents the seasonal and inter-annual variability of the CC during 2003–2017 in three different regions along the ARC pathway, which are selected based on the circulation pattern, bathymetry, and local dynamics. The study also identified the effect of the polar water in the variation of the chlorophyll.

Behera, N., Sil, S., & Swain, D. (2020). Seasonal and interannual variations of Chlorophyll-a concentrations in Agulhas return current region. Regional Studies in Marine Science, 101423.


Chlorophyll-a concentration over Sri Lankan Dome in the Bay of Bengal


We studied the inter-annual variability of Chlorophyll-a Concentration (CC) over the Sri Lankan Dome (SLD) surface and subsurface in the Bay of Bengal (BoB). A regional ocean modelling system (ROMS) coupled with a nitrogen-based nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecosystem model has been used to simulate the three-dimensional SMC and the upwelling system over the SLD region during 2003–2016.

Pramanik, S., Sil, S., Gangopadhyay, A., Singh, M. K., & Behera, N. (2020). Interannual variability of the Chlorophyll-a concentration over Sri Lankan Dome in the Bay of Bengal. International Journal of Remote Sensing, 1–18.

Sea-ice extent is very sensitive to climate change and its minor variations can significantly affect the regional biota of the Southern Ocean (SO). Chlorophyll-a concentration (Chl-a) is a primary proxy for the understanding of phytoplankton distribution and primary productivity in the oceans. Therefore, analysing the relation between Chl-a and sea-ice extent could be significant in understanding the role of SO sea-ice extent on regional Chl-a variability. Local Chl-a variability in the SO was analysed in five major sectors, utilizing 39 years of remotely sensed sea ice and 15 years of Chl-a and Sea Surface Temperature (SST) datasets. To understand the vertical variation of physical and biogeochemical variables and their influence on Chl-a variability, data from a few active Biogeochemical-Argo floats in the region were analysed.

Behera, N., Swain, D., & Sil, S. (2020). Effect of Antarctic sea ice on chlorophyll concentration in the Southern Ocean. Deep Sea Research Part II: Topical Studies in Oceanography, 104853.