A CLIMATIC ANALYSIS OF SUMMER PRECIPITATION FEATURES AND ANOMALY IN NORTHEAST CHINA

KeyWord:Northeast China;Summer rainfall anomaly;Rotated principal componentanalysis;Wavelet analysis;Catastrophe analysis

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.