关键词: 青藏高原, 西南地区降水, 非绝热加热

Abstract:

With the meteorological observation data and reanalysis data set, the interannual variation of the precipitation over Southwest China and the anomalies of the accompanying circulations and diabatic heating were analyzed firstly using statistical methods. It is shown that, when the total of precipitation over Southwest China was more than normal, one dipole of cyclonic and anticyclonic atmospheric circulations along the east-west direction was located in the middle and upper troposphere over south of the Yangtze River and over southwest regions of the Qinghai-Tibetan Plateau respectively; over Southwest China, the anomalous northerly and southerly wind dominated the upper and lower troposphere respectively, and the anomalous diabatic heating source was lied in the regions where the anomalous ascending motion prevailed; the descending motion anomaly and the anomalous diabatic heating sink almost concurred in the middle troposphere over the southwest of the Qinghai-Tibetan Plateau. When the total of the precipitation over Southwest China was less than normal, the opposite is the case with the aforementioned. Furthermore, the dynamical diagnosis was used to reveal the possible physical process of the precipitation anomaly in Southwest China. That is, the abnormal ascent of one part of the South Branch to the southwest side of the Qinghai-Tibetan Plateau, by affecting the total amount of water vapor transport downstream and then the diabatic heating anomalies in Southwest China, eventually played a role in modulation of the precipitation in Southwest China.

Key words: Qinghai-Tibetan Plateau, the precipitation over Southwest China, diabatic heating