Characteristic of South Asia High Activity and Its Relation with the Precipitation of East China in Summer
Characteristic of South Asia High Activity and Its Relation with the Precipitation of East China in Summer
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发表时间：
2010
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通讯作者：
HU Jing-gao
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作者：
HU Jing-gao
利用1979-2007年NCEP/DOE再分析2逐日资料和国家气象信息中心595站观测资料，分析了南亚高压脊线和东岭点的日平均变化及其与我国东部夏季降水的关系。发现5月第3候脊线突然北移。突变发生在南海夏季风爆发前一候。在4月下旬的北移过程中，脊线有一个南退的过程。4月下旬中部脊线位置偏北方，比东岭先北跳，8月以后位置偏南。南亚高压在6月中旬至7月上旬有一次东进过程。东岭点存在周时间尺度的振荡。同时相关分析表明，在分析江淮流域和华南夏季降水时，东岭点的纵向位置是SAH较好的特征参数。但在黄河下游地区转向夏季干旱区时，SAH脊线是一个相对可取的选择。合成分析表明，华北、东北部分地区处于汛期，华南处于干旱期，南半球高空高压强度在东偏年增大，西偏年减小。
The daily mean variations of the ridge line and the east ridge point of South Asia High (SAH) and the relation with precipitation of East China in summer are studied using the about 30-year (1979—2007) Daily NCEP/DOE Reanalysis 2 data and observational data at 595 stations given by National Meteorological Information Center. It is founded that the ridge line changes abruptly northward in the third pentad of May. The time of abrupt change is one pentad before the one of SCS Summer Monsoon onset. There is a southward retreat of the ridge line in the last decade of April during the northward movement. The middle ridge lines keep more northern positions and jump northward earlier than the east ridge lines in late April while they locate southerly after August. The SAH has a eastward advancing from the mid of June to early July. There is a weekly time scale oscillation of the east ridge point. The simultaneous correlation shows the longitudinal positions of the east ridge point are better characteristic parameters of SAH when analyzing the summer precipitation of the Yangtze River-Huaihe River Basin (YHB) and South China. But when turning to the summer rainfalls in the lower reaches of the Yellow River basin,the ridge line of SAH is a relatively advisable choice. Composed analysis indicate that YHB,some parts of Northeast China are in a flood period and South China are in a drought period,meanwhile SAH intensity increases during east deviation years,and vice verse during west deviation years.