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.