Net Sea–Air CO$_{2}$ Fluxes and Modeled Partial Pressure of CO$_{2}$ in Open Ocean of Bay of Bengal

The key role of oceans in the global climatic system can be accurately quantified by the measurement of CO
₂
exchange across air-sea interface. The direction and magnitude of this CO
₂
exchange are mainly governed by the gradient of partial pressure of carbon dioxide (pCO
₂
) at the air-sea interface. The sea surface pCO
₂
is highly variable, primarily regulated by seasonal sea surface temperature (SST) and CO
₂
(aqueous) concentration. In this paper, the moored pCO
₂
observations from autonomous pCO
₂
system deployed at 15 °N 90 °E in the Bay of Bengal (BOB) were used to derive CO
₂
fluxes to examine variability over time scale at BOB. An attempt has also been made to develop a model using multiple linear regression (MLR) and support vector regression (SVR) to estimate the sea surface pCO
₂
from space-based observations of SST and salinity. pCO
₂
variability was primarily attributed to SST and CO
₂
concentration changes. Derived fluxes showed that BOB is a net annual source (0.440 g-C/m
²
/year for year 2014) of CO
₂
at mooring location with significant seasonality effects. For the estimation of surface pCO
₂
, SVR model showed better results [root mean square error (RMSE) = 7.68 μatm] in comparison to MLR model (RMSE = 12.36 μatm). The seasonal climatological pCO
₂
maps from September 2011 to February 2018 showed southward increase in pCO
₂
in all seasons possibly due to southward increase in SST and less influence of river water. These pCO
₂
maps can further be utilized in deriving CO
₂
flux maps for BOB.