Strong CO 2 emissions from the Arabian Sea during south‐west monsoon

The partial pressure of CO 2 ( p CO 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 µatm. The stable atmospheric p CO 2 level was around 345 µatm. An extreme supersaturation was found in areas of coastal upwelling off the Omani coast with p CO 2 peak values in surface waters of 750 µatm. 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 p CO 2 of up to 525 µatm. 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 CO 2 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 CO 2 concentrations, which are consistent with such strong emissions.