Persistently strong oceanic CO2 sink in the western subtropical North Pacific -: art. no. L05612

The long-term trend of the partial pressure of CO2 in surface seawater ( pCO(2)(sea)) in late-January to early-February during the past two decades was examined in the western North Pacific along the repeat line at 137 degrees E from 3 degrees N to 34 degrees N. The growth rate of pCO(2)(sea) at each 1 degrees in latitude ranged from + 1.3 +/- 0.2 to + 2.1 +/- 0.3 matm yr(-1), and the average was + 1.7 +/- 0.2 matm yr(-1). The growth of pCO(2)(sea) is attributable mainly to the uptake of anthropogenic CO2 in surface water and, to a small extent, to the regional changes in sea surface temperature ( SST). The net air-to-sea CO2 flux in January-February that accounts for 40 to 60% of the annual flux remained at a similar level in the subtropical regions ( 7 degrees N to 34 degrees N). In the equatorial region ( 3 degrees N to 6 degrees N), however, a slight increase in the CO2 efflux was seen.