The Simulation And Assessment Of The Impact Of The Mid-high Latitude And Low Latitude Circulation On Summer Precipitation In Eastern China

Based on the surface daily precipitation data of China and ERA-Interim reanalysis, the temporal and spatial characteristics of summer precipitation in Eastern China are studied by using correlation analysis, EOF analysis, and others, meanwhile the relationship between four types of precipitation distribution and atmospheric circulation is analyzed. On the basis of above, summer precipitation in Eastern China is simulated by RegCM4, and the high and low latitude circulation how to effect the variation of summer precipitation in the northern and southern of China is explained by the north and south lateral boundary sensitivity experiments.There are four main patterns of spatial distribution of precipitation in eastern China: the South China pattern, the Yangtze-Huaihe pattern, the opposite pattern of the Yangtze and Huaihe River, and the south-north pattern. The specific configuration of vertical circulation in high, middle and low layers in East Asia has a significant effect on different patterns of precipitation in the eastern of China, which underscores the interaction between the high and low latitude atmospheric circulation.Th RegCM4 could better simulate the space distribution of the average summer precipitation and the inter-annual variation in the east areas of China, and the inter-annual variation of the simulated precipitation in the south areas is relatively low while the interannual variability of precipitation in the north areas is near to that observed. Form correlation coefficient,it's simulated well in the southeast coast of China and Northeast China while it's poorly simulated in North China. The model can simulate reasonably the differentce of the drought and flood years' precipitation and whole layer vapor transportation in the eastern of China, which indicates the model show good performance in simulating variability of summer precipitation over China.By the lateral boundary sensitivity experiments, the results are as follows: By getting rid of the inter-annual variation of the lateral border force in high latitudes,the summer precipitation is overestimated in the eastern of China, the inter-annual variation intensity of summer precipitation in both Southern China and Northern China is weakened significantly, and the inter-annual variation intensity of the whole layer vapor transportation in most parts of eastern China is weaked. The space distribution of the drought and flood years' precipitation in Southern China is changed little and the difference intensity is decreased. The space distribution of the drought and flood years' precipitation in Northern China is changed significantly and the spatial distribution difference isn't obvious. By removing the inter-annual variation of the lateral border force in low latitudes, the summer precipitation is underestimated in the southern of China and it's overestimated in Yangtze River and North area, the space distribution of the precipitation is changed significantly in Sorthern China. The inter-annual variation intensity of summer precipitation in both Southern China and Northern China is changed little but the inter-annual variation intensity of the whole layer vapor transportation in most parts of eastern China is weaked. The space distribution of the drought and flood years' precipitation in Southern China is changed significantly and the rain belt northward to the Yangtze River Basin in the flood years. The space distribution of the drought and flood years'precipitation in Northern China isn't changed and the difference intensity is changed little.Therefore the mid-high latitude lateral border force mainly influences the inter-annual variation intensity of summer precipitation in both Southern China and Northern China and the extreme drought and flood years' space distribution of precipitation in Northern China, the low latitude lateral border force has a great impact on space distribution of precipitation in Southern China, especially in extreme drought and flood years.