THE RELATIONSHIP BETWEEN SUMMER PRECIPITATION IN CHINA AND CIRCULATION ANOMALY IN EUROASIA AND ITS APPLICATION IN PRECIPITATION PREDICTION

KeyWord:SVD;500 hPa circulation;Precipitation prediction

Abstract:

      Coupling action between 500 hPa height field and summer precipitation distribution in China has been analysed by SVD (Singular Value Decomposition) method. The following results are revealed. (1) The coupling between summer 500 hPa height field and precipitation distribution is associated with the teleconnection of atmospheric circulation. The first pattern of the coupling shows spatial distribution reflecting the characters of the EPA and EU pattern of atmospheric circulation and the precipitation distribution. High correlation areas are mostly associated with atmospheric activity centers. When blocking high is located in north eastern Asia, the western Pacific subtropical high is stronger than normal with its position to further south of the normal, the meridian circulation prevails in middle and high latitudes, the major rain belt is located in southern China, severe flooding appear more frequently in the Yangtze river basin. In the opposite situation, precipitation in the Yangtze River basin is below normal or even drought. (2) The precipitation time coefficient of the coupling action can at describe well drought and flooding distribution, especially at distinguishing rain belt patterns (north or south). This precipitation time coefficient may reflect decade variability of summer precipitation pattern in China. (3) The analysis to the coupling between the 500 hPa circulation characteristics in winter, spring seasons and the summer precipitation distribution shows that from previous winter present to summer, the coupling characteristics between 500 hPa height field and precipitation distribution have persistence. Previous circulation influences summer precipitation distribution through rhythm relationship and thermodynamic condition contrast between land and ocean. (4) With the results from SVD analysis and previous circulation anomaly, a forecast model for summer precipitation in China is established. The prediction experiment shows a certain capability.