Regional difference of annual precipitation and discharge variation over west China during the last 50 years

Using annual precipitation and discharge data measured in the past five decades, this paper analyzed the regional differences over west China in terms of climate and discharge variations, and investigated the relationship between the regional characteristics and the activities of South and East Asian summer monsoon. Results revealed that the precipitation and discharge in the upper reaches of the Yellow River (Central West China) have a negative correlation with those in Xinjiang (northwest China) and the Yarlung Zangbo River (the upper reaches of the Brahmaputra Rive, southwest China) regions. The geographical patterns of precipitation and discharge variations are different over west China, i.e. the regional climate displays the alteration of dry-wet-dry or wet-dry-wet from north to south in west China. The negative correlation of annual discharges between Xinjiang and the upper reaches of the Yellow River is found statistically significant in the decadal scale, and that between the Yarlung Zangbo River and the upper reaches of the Yellow River is found active in the interannual scale. The regional characteristics indicate that the discharge/precipitation variations in the upper reaches of the Yellow River are dominated by the East Asian summer monsoon while their variations in Xinjiang are affected by both the west wind and East Asian summer monsoon.