Air‐sea flux of CO2 in the Arctic Ocean, 1998–2003

Abstract

The Arctic Ocean has experienced an unprecedented reduction in sea ice over the last 3 decades, increasing the potential for greater exchange of gases such as carbon dioxide (CO2) between the atmosphere and the upper ocean. The present study utilizes remotely sensed data on distributions of both sea ice and chlorophyll a, together with modeled temperature and salinity fields, to obtain high‐resolution basin‐scale estimates of the air‐sea flux of CO2 (FCO2) in the Arctic Ocean for the years 1998–2003. Concentrations of dissolved inorganic carbon (DIC) were derived from multiple linear regression relationships with sea surface temperature, salinity, and chlorophyll a. The partial pressure of carbon dioxide (pCO2) in surface waters was computed from DIC and alkalinity, the latter of which varied with salinity. FCO2 was calculated from the air‐sea difference in pCO2 and wind speed. Annual FCO2 was highest in the Atlantic‐dominated Greenland and Barents sectors due to their lower sea ice cover, although area‐normalized FCO2 in these sectors was low. Only the Siberian sector exhibited a significant increase in annual FCO2 during the time of our study, due to a corresponding increase in ice‐free water. Overall, the Arctic Ocean was a net atmospheric sink for CO2, with annual FCO2 averaging 118 ± 7 Tg C yr−1 during 1998–2003.