Re-visit the Linkage between Spring Arctic Sea Ice and East Asian Summer Precipitation

Abstract:

The linkage between the spring Arctic sea ice and the East Asian summer monsoon is controversial in terms of both the impact regions and the responsible mechanism. In this study, four sea ice datasets (HadISST1, HadISST2.2, ERA-Interim and NOAA/NSIDC) and two global gridded precipitation datasets (CRU V4.01 and GPCP V2.3) are used to investigate the co-variation between spring Arctic sea ice cover (SIC) and East Asian summer precipitation. The results show that the spring (March-April-May, MAM) Bering SIC (BSIC) is significantly correlated with the summer (June-July-August, JJA) rainfall in the Lake Baikal-Northestern China (Baikal-NEC) in all the datasets. Based on the reanalysis and numerical sensitivity experiments, we found the mechanism on how the spring BSIC impacts the East Asian summer precipitation as followings: the high MAM BSIC triggers a wave train and causes a positive SLP anomaly in the North Atlantic from March to June. The high SLP anomaly associated with anti-cyclonic circulation is in favor of a mean zonally dipole-pattern anomaly in sea surface temperature (SST) during summer. The dipole-SST pattern in the summer drives a zonally-orientated wave train propagating from the mid-latitude North Atlantic to the Sea of Japan through Eurasian continent, which leads to a high anomaly geopotential height at 500hPa appearing over the Sea of Japan in summer. It indicates that the mean East Asian trough moves westward to the Baikal-NEC region where a deep low anomaly in SLP prevails. The prevailed low pressure over the Baikal-NEC is beneficial for more rainfall with enhanced moisture transport from the west North Pacific and converging over the Baikal-NEC.