西太平洋暖池海温对华南前汛期降水影响的数值试验

简要地介绍了全球大气环流模式CCM3,由该模式模拟得到降水、位势高度场和风场,分析它的模拟性能。根据华南前汛期(4～6月)降水与西太平洋暖池敏感海区(西区)海温的负相关关系,设计了两组敏感性试验,讨论西区海温对华南前汛期降水影响的确定性和可能的物理机制。模拟结果表明,当西区为冷水年(暖水年)时,华南降水偏多(少),长江中下游相对偏少(多),相关最好的地区是广东省,与诊断分析结果相符。海温对降水的影响是通过大气环流场来实现的,因此,再用P-σ九层区域气候模式模拟了西区海温异常年大气环流对华南前汛期降水的影响,与CCM3模拟结果基本一致。

NUMERICAL STUDY OF INFLUENCE OF THE SSTA IN WESTERN PACIFIC WARM POOL ON PRECIPITATION IN THE FIRST FLOOD PERIOD IN SOUTH CHINA

A brief introduction of a global atmospheric circulation model CCM3 is made and the CCM3 is used to simulate the precipitation of China, the height and the flow fields. The reliability of simulation is analyzed. According to the negative correlation between precipitation in the first flood period in South China (SC) and SSTA in a key region in western Pacific warm pool (West Region) , two sensitive experiments are designed to investigate the effects of the latter on the former and the possible physical mechanism is discussed. It is found that when the West Region is occupied with the negative SSTA, the rainfall in SC is far more than usual, while the rainfall in the middle and low reaches of the Yangtze River is relatively less. In warm water years, the case is reversed. The best correlative area of precipitation is located in Guangdong Province. It matches the diagnostic result well. The effect of SSTA on precipitation in SC is realized through the abnormality of atmosphere circulation and tested by ap-σ nine-layer regional climate model. Moreover, the simulative result of the p-σ model is basically coincident with that of the CCM3.