The fraction of East Asian interannual climate variability explained by SST in different seasons: an estimation based on 12 CMIP5 models

Using the output of 12 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5), this study assessed to what extent is the interannual climate variability over East Asia explained by sea surface temperature (SST). By comparing the atmospheric component model simulations forced by observed interannual varying SST and fixed annual cycle of SST, the fraction of interannual variability explained by SST is estimated. Although SST explains a major fraction of interannual variability of both seasonal mean surface air temperature (SAT) and precipitation over tropical western Pacific, it only explains about 0-30% of the interannual variance over East Asian land. The SST explains a greater fraction of interannual SAT variance in summer, since the SAT variance induced by non-SST factors is relatively small possibly due to the weaker impact by mid-latitude eddy activities. During winter and spring, SST accounts for a larger fraction of interannual precipitation variability over southern China than in summer and autumn, due to the stronger modulation of El Nino-Southern Oscillation-related SST anomalies through the anomalous anticyclone over western north Pacific from winter to spring.