STUDIES ON SPATIAL-TEMPORAL CHARACTERISTICS OF YUNNAN RAINY SEASON AND ITS RELATIONSHIP WITH ATMOSPHERIC CIRCULATION
YAN Hong-ming
LI Qing-quan
WANG Dong-qian
Abstract：Based on the station standard of southwest rainfall season,the temporal and spatial features of Yunnan rainy seasons were investigated using 116 meteorological observation stations data from 1951-2015.At the same time,the influence of atmospheric circulation on Yunnan rainy seasons were further studied.The results are shown as follows:(1) For the 30-year (1981-2010) climatic mean,the beginning and ending date of Yunnan averaged rainy seasons are respectively on May 22 and October 15.The spatial differences of Yunnan rainy season variation are obvious in different region.The rainy season begins gradually from the southeast to the northwest and ends gradually from the northwest and southeast to the southwest,causing the length and total precipitation of the rainy season to decrease gradually from the south to the north;(2) For the beginning and ending date of annual rainy seasonsin Yunnan for 1961-2015,the earliest beginning date is May 8th and the latest date is June 8th.The endingdate is as early as September 30th and the latest November 2nd;(3) The changes of Yunnan rainy seasons are influenced jointly by the southwest monsoon and mid-latitude cold air.The early (late) establishment of southwest monsoon and frequent influence of cold air coming from the mid-latitude region may result in an early (late) rainy season.Different from the start of the rainy season,the end of a Yunnan rainy season is mainly affected by the tropical monsoon circulation.With early (late) shift of seasonal circulation from summer monsoon to winter monsoon,the Yunnan rainy season ends early (late).
Keywords：low-latitude plateaucriterion of Yunnan rainy seasonbeginning and ending of rainy seasonsouthwest monsooncold air activitiesin mid-high latitudes
Publication Date：2018-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：11( 12-22 )