Environmental controls on the seasonal carbon dioxide fluxes in the northeastern Indian Ocean

Abstract

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Total carbon dioxide (TCO₂) and computations of partial pressure of carbon dioxide (pCO₂) had been examined in Northerneastern region of Indian Ocean. It exhibit seasonal and spatial variability. North-south gradients in the pCO₂levels were closely related to gradients in salinity caused by fresh water discharge received from rivers. Eddies observed in this region helped to elevate the nutrients availability and the biological controls by increasing the productivity. These phenomena elevated the carbon dioxide draw down during the fair seasons. Seasonal fluxes estimated from local wind speed and air-sea carbon dioxide difference indicate that during southwest monsoon, the northeastern Indian Ocean acts as a strong sink of carbon dioxide (-20.04 mmol m ^–2 d^-1). Also during fall intermonsoon the area acts as a weak sink of carbon dioxide (-4.69 mmol m ^–2 d^-1). During winter monsoon, this region behaves as a weak carbon dioxide source with an average sea to air flux of 4.77 mmol m^-2 d^-1. In the northern region, salinity levels in the surface level are high during winter compared to the other two seasons. Northeastern Indian Ocean shows significant intraseasonal variability in carbon dioxide fluxes that are mediated by eddies which provide carbon dioxide and nutrients from the subsurface waters to the mixed layer</smarttagtype>