The central and eastern Arabian Sea as a perennial source of atmospheric carbon dioxide

Seasonal (winter monsoon, intermonsoon and southwest monsoon) and interannual (between southwest monsoon seasons of 1995 and 1996) variations in total carbon dioxide (TCO2) and partial pressure of CO2 (pCO(2)) were studied in the central and eastern Arabian Sea as a part of the JGOFS (India) Programme. The pCO(2) values were computed from the results of coulometric TCO2 and spectrophotometric pH measurements. Seasonal variability in TCO2 is evident with the changing circulation and biological production. In all seasons, the pCO(2) is higher in surface waters of the Arabian Sea, except along the Indian coast in the southwest monsoon, than that in atmosphere, and thus this region appears to be a perennial source of atmospheric CO2. Significantly, an average of similar to 45 Tg y(-1) could be ejected to atmosphere from the study region, that seems to far exceed the earlier estimations. The estimated fluxes, however, are in agreement with those from the eastern equatorial Pacific Ocean.