Atmospheric impact on the northwestern Pacific under a global warming scenario

Abstract

Eleven climate models, one high-resolution and ten low-resolution, were analyzed to investigate the response of the northwestern Pacific under a global warming scenario. Application of scenario A1B of the Special Report on Emission Scenarios (SRES) weakens (intensifies) the southern (northern) part of the interior subtropical gyre both in high-resolution and low-resolution model. Such a dipole type change is mainly due to a basin-scale dynamic atmosphere-to-ocean process. Namely, under global warming the Hadley circulation is weakened and expanded poleward. The Ferrel circulation is also displaced poleward, leading to weakening of ascending (descending) air motion and a high (low) sea level pressure anomaly in the northwestern (southeastern extratropical) North Pacific. Finally, a negative wind stress curl anomaly developed along the zero wind stress curl line of the present-day climate to enhance the northern part of the gyre. The high-resolution model results show greater changes in the structure of the Kuroshio and Kuroshio Extension, with strong intensification of the Kuroshio Extension front and jet, while in the low-resolution models the changes are small. The Kuroshio between Taiwan and the southern coast of Japan is significantly intensified in the high-resolution model results, but is slightly weakened in the ensemble of the low-resolution models. © 2012. American Geophysical Union. All Rights Reserved.