从湿季降水分异论哀牢山季风交汇

Discussion on Monsoons′ Interfacing Around Ailaoshan Through Analyzing Regional Variation of Wet Season Rainfall

选择哀牢山和无量山中南部区域,利用该区1961—2007年月降水资料,分析湿季及各月降水时空分异与区域地形及季风交汇的关联。结论如下:区域湿季降水与岭谷地形的空间分异有着很好的吻合。哀牢山东侧主脉两侧降水量分异明显,但两侧各站湿季及各月降水的年际变化趋势等多项特征具有一致性。该区东南部和西北部的湿季降水存在明显分异,中间地带具有过渡性;西北部和东南部站点间湿季各月月降水相关性呈规律性变化。2支季风在本区的交汇态势随季风发展而变化;西南季风爆发初期,2支季风交汇中心在无量山脉至哀牢山西侧支脉一带;2支季风强盛期,二者在全区交汇;东南季风退缩期,2支季风交汇中心移至哀牢山脉的南段区域。

Since the 1960s,Ailaoshan in southern Yunnan has been thought as the boundary of southwest monsoon and southeast monsoon,which significantly determine regional climatic variation as well as other landscape heterogeneities.Through using monthly rainfall data from 1961 to 2007 at all the 11 meteorological stations in the central-southern region of Ailaoshan and Wuliangshan,this study first analyzed the spatio-temporal variation characteristics of rainfall in wet season and each month within that period,then discussed the links between the spatio-temporal variation and regional topographical feature and the two monsoons.The rainfall characteristics in wet season and each month showed there existed obvious variation between the southeast part and the northwest part of study area,while the central part had obviously transitional characteristics.Wet season rainfall on the southwest slope of the eastern range of Ailaoshan is far higher than that of the northeast valley（rain shadow） of the eastern Ailaoshan range.But,within both sides of the eastern Ailaoshan range,wet season rainfall decreased gradually from southeast to northwest.Correlation co-efficiencies of monthly rainfall between neighbouring stations within the eastern Ailaoshan range always kept high in wet season.But correlation co-efficiencies of monthly rainfall between the northwest and the southeast stations showed obviously fluctuation.The interfacing condition of southeast monsoon and southwest monsoon in wet season in this region varied with the development of monsoons.Average onset and shrinkage dates of southeast monsoon are both earlier than these of southwest monsoon.With the onset of southwest monsoon,the interface region of these two monsoons in earlier wet season is the Babian River basin.In June and July,the two monsoons gradually became strong and interface with each other within the whole region.Within the drawback procedure of the southeast monsoon,the interface region of the two monsoons moved to the southern part of Ailaoshan.