Recent deceleration of oceanic pCO2 increase in the western North Pacific in winter

Recent changes in oceanic CO2 partial pressure (pCO(2)(sea)) have attracted increasing interest as they relate to the increase in atmospheric CO2 and climate change. We report decadal changes in the growth rates of pCO(2)(sea) in latitudinal zones from 3 degrees N to 33 degrees N along the repeat hydrographic line at 137 degrees E in the western North Pacific in winter. The growth rates of pCO(2)(sea) for 1999-2009 (-0.3 +/- 0.9 [mean +/- 1 sigma] to 1.7 +/- 0.5 mu atm yr(-1)) were lower than those for 1984-1997 (0.7 +/- 0.3 to 2.2 +/- 0.6 mu atm yr(-1)) at most latitudes, indicative of the recent notable deceleration of pCO(2)(sea) increase. For latitudes around 10-20 degrees N, we attribute the reduction in the growth rate of pCO(2)(sea) for 1999-2009 primarily to the reduction in the contribution from dissolved inorganic carbon (DIC) originating from a reduction in carbon accumulation associated with the expansion of the western Subtropical Gyre towards the south. Citation: Midorikawa, T., M. Ishii, N. Kosugi, D. Sasano, T. Nakano, S. Saito, N. Sakamoto, H. Nakano, and H. Y. Inoue (2012), Recent deceleration of oceanic pCO(2) increase in the western North Pacific in winter, Geophys. Res. Lett., 39, L12601, doi:10.1029/2012GL051665.