Strong CO2 emissions from the Arabian Sea during South-West Monsoon

The partial pressure of CO2 (pCO(2)) was measured during the 1995 South-West Monsoon in the Arabian Sea. The Arabian Sea was characterized throughout by a moderate supersaturation of 12-30 mu atm. The stable atmospheric pCO(2) level was around 345 mu atm. An extreme supersaturation was found in areas of coastal upwelling off the Omani coast with pCO(2) peak values in surface waters of 750 mu atm. Such two-fold saturation (218%) is rarely found elsewhere in open ocean environments. We also encountered cold upwelled water 300 nm off the Omani coast in the region of Ekman pumping, which was also characterized by a strongly elevated seawater pCO(2) of up to 525 mu atm. Due to the strong monsoonal wind forcing the Arabian Sea as a whole and the areas of upwelling in particular represent a significant source of atmospheric CO2 with flux densities from around 2 mmol m(-2) d(-1) in the open ocean to 119 mmol m(-2) d(-1) in coastal upwelling. Local air masses passing the area of coastal upwelling showed increasing CO2 concentrations, which are consistent with such strong emissions.