Surface temperature‐related variations in the East Asian summer monsoon during three warming stages

Abstract

AbstractThe global mean surface temperature has experienced different warming stages, but there is less work on discussion of the regional climate changes under the background of different global warming rates. This study investigated the surface temperature (ST)‐related trends in the East Asian summer monsoon (EASM) and underlying mechanisms during three warming stages, with a view to develop a new understanding of the responses of the EASM to global warming. Based on the statistical method of piecewise linear regression (PLR) to ST anomaly time series, the ST variation process from 1958 to 2014 has been divided into three stages with different linear trends: 1958–1975 (hiatus), 1976–1997 (acceleration) and 1998–2014 (slowdown). During the first stage, accompanied by two anomalous lower‐level cyclones, a weakening trend of the southerly winds over eastern China is observed. The enhanced cyclone over the Yellow Sea, with local ST cooling, is associated with the CGT‐like (circumglobal teleconnection) pattern, while the other one over the Philippines can be attributed to the local sea surface temperature (SST) warming. The ST‐related anomalous EASM circulation exhibits an enhanced lower‐level anticyclone over the northern Philippine Sea during the second stage. The warming around Lake Baikal and the phase change of the East Atlantic/Western Russia (EAWR) pattern can weaken upper‐level East Asian jet stream (EAJS) and then provide a favourable condition for the descent related to the lower‐level anticyclonic anomaly. As for the third stage, the anomalous ST and related EASM circulation both display a dipole pattern. Through influencing the meridional thermal contrast and distribution of convergence over East Asia (EA), the interaction between anomalous ST and EASM circulation may be the major mechanism that results in the increased (decreased) ST and enhanced barotropic anticyclone (cyclone) over southern (northern) EA.