摘要:
利用中国东北三省69个测站,1961～1995年6～8月降水量资料,采用EOF、REOF、小波分析及突变分析等方法,对夏季降水量的空间异常特征和时间变化规律进行了诊断研究。结果表明:东北地区夏季降水异常的空间分布既有整体一致的性质,也存在着南部和北部及东部和西部相反变化的差异,并且可以把整个东北地区划分为7个主要的降水异常型:辽东半岛型、西部平原型、中南部型、东部山区型、三江平原型、辽西型和东北北部型。近90a来,东北地区夏季降水主要呈多雨、少雨或是波动等阶段性变化,没有明显的变干或是变湿倾向。各异常型代表站资料反映出近35～45a中,东北地区1960年代中期至1980年代初降水的减少比较明显,具有突变性质,1980年代总体上讲降水有一定程度的增加,1990年代处于旱涝交替出现的波动状态。东北地区夏季降水主要有34,22,11a以及2～4a左右的周期变化,但各异常区所盛行的主要周期以及同一异常区在不同年代所盛行的主要周期均有所差异。
Abstract:
With EOF, REOF, Waveletanalysis and catastrophe analysis methods, the spati al anomaly features and time evolution rule of summer precipitation in northeast China are studied by using the precipitation data in June, July and August for the period 1961～1995 from 69 observational stations. The results show that the first three loading vector field could reflect whole anomaly structures of summer rainfull in northeast China, for example, wet or dry in all area pattern, wet (or dry) in south and dry (wet) in north pattern, wet (or dry) in east and dry (wet) in west pattern. The first seven rotated loading vector fields repersent seven principal precipitation anomaly areas:Liaodong peninsula, the west plain, the middle-south area, the east mountain area, the three rivers plain, the west of Liaoning and the north of the northeast China. The data of the representative stations show that in the recent 35-45 years, the precipitation decrease in northeast China is obvious from the middle 1960's to the early 1980's and has cata strophe character. From the 1980's to the middle 1990's, an increasing rainfall trend, more or less, appeared in majority areas. The summer rainfall in northeast China have about 40, 22, 11 and 2-4 years periodic variations. But the prevailing periods exsit differences among different areas and different times in the same area.
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