Interannual variability of atmospheric heat source/sink over the Qinghai—Xizang (Tibetan) Plateau and its relation to circulation

Abstract

Based on the 1961–1995 atmospheric apparent heat source/ sink and the 1961–1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961–1995 reanalysis data of NCEP/ NCAR and the 1975–1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation. It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) summer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and its neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo—China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.