THE NUMERICAL SIMULATION OF THE RELATIONSHIP BETWEEN THE INTER-ANNUAL VARIATION OF SUMMER PRECIPITATION IN SOUTH CHINA AND THE HIGH AND LOW LATITUDE CIRCULATION

SUN Qing-fei; YAO Su-xiang

doi:10.16032/j.issn.1004-4965.2017.06.015

Abstract：30 years' numerical simulation of precipitation and associated circulation over Southern China in the summer is carried out by RegCM4.4.By comparison with the observed data of rainfall,it finds that this model could better simulate the spatial distribution of the average summer precipitation and the inter-annual variation in the eastern areas of China,and the inter-annual variation of the simulated precipitation in the southern areas is relatively low.The correlation coefficient between the observed average summer precipitation and the simulated precipitation over Southern China is 0.51.The result of the simulation and observation shows that in typical flood years the northeasterly ahead of the middle-latitude anomalous anticyclone joins the southwesterly behind the low-latitude anomalous anticyclone in Southern China,which results in heavy precititation,and this model has the ability to simulate the inter-annual variation of summer precipitation in Southern China.By the lateral boundary sensitivity experiments,the inter-annual variation intensity of summer precipitation in Southern China is weakened significantly but the spatial distribution of the precipitation in drought and flood years changes little by getting rid of the inter-annual variation of the lateral border forcing in high latitudes,while the inter-annual variation intensity of summer precipitation in Southern China is nearly invariable but the spatial distribution of the precipitation in drought and flood years changes significantly by removing the inter-annual variation of the lateral border forcing in low latitudes.The mid-high latitude lateral border forcing mainly influences the inter-annual variation intensity of summer precipitation in Southern China but changes little the inter-annual variation of the space distribution while the low latitude lateral border forcing does quite the opposite.