Origin of the spatial consistency of summer precipitation variability between the Mongolian Plateau and the mid-latitude East Asian summer monsoon region

作者：Jie CHEN,Wei HUANG,Qiong ZHANG,Song FENG

摘要：The Mongolian Plateau(MP) is located in the eastern part of arid Central Asia(ACA). Climatically, much of the MP is dominated by the westerly circulation and has an arid and semi-arid climate;however, the eastern part of the MP is also influenced by the East Asian summer monsoon(EASM) and has a humid and semi-humid climate. Several studies have shown that precipitation variability in the MP differs from that in western ACA but is consistent with that in the EASM region. Here we use monthly precipitation data for 1979–2016 to characterize and determine the origin of the summer precipitation variability of the MP and the EASM region. The results show that the MP and the mid-latitude EASM region exhibit a consistent pattern of precipitation variability on interannual and decadal timescales;specifically, the consistent regions are the MP and North and Northeast China. We further investigated the physical mechanisms responsible for the consistent interdecadal precipitation variability between the MP and the mid-latitude EASM region, and found that the mid-latitude wave train over Eurasia, with positive(negative) geopotential height anomalies over the North Atlantic and ACA and negative(positive) geopotential height anomalies over Europe and the MP, is the key factor responsible for the consistency of precipitation variability in the MP and the mid-latitude EASM region. The positive anomalies over the North Atlantic and ACA and negative anomalies over Europe and the MP would enhance the transport of westerly and monsoon moisture to the MP and North and Northeast China. They could also strengthen the Northeast Asian low, enhance the EASM, and trigger the anomalous ascending motion over the MP which promotes precipitation in the MP and in the mid-latitude EASM region. Overall, our results help explain the spatial variations of paleo-precipitation/humidity reconstructions in East Asia and clarify the reasons for the consistency of the regional climate.

发文机构：Key Laboratory of Western China s Environmental Systems（Ministry of Education） Department of Physical Geography and Bolin Centre for Climate Research Department of Geosciences

关键词：MongolianPlateauMid-latitudeEASMregionSummerprecipitationDECADALConsistentvariability

分类号： P426.614[天文地球—大气科学及气象学]