短期气候数值预测中海温和初始场作用的敏感性试验

SENSITIVE EXPERIMENTS ON THE FIELDS OF SST AND ATMOSPHERIC INITIAL CONDITIONS OF THE NUMERICAL SHORT TERM CLIMATE PREDICTION

该文利用 AGCM L2 AGCM1 - 1模式 ,对两种类型的大气初始场 ( ICs)异常和海表温度( SST)异常进行了一系列的跨季度敏感性试验 ,用大量的试验结果考察了 ICs异常和 SST异常对东亚夏季 50 0 h Pa高度场和降水距平场的影响 ,得到以下主要结论 :热带东太平洋的 SST异常型对我国夏季降水有非常显著的作用 .在 El Nino型 SST异常影响下 ,我国从西南到华北地区降水距平为负 ,东南沿海到日本及其以东海域为较强的正距平 ,中心位于海上 ,当 SST异常为 La Nina型时 ,我国东南沿海的正距平区向西、向北伸展 ,中心位于江淮流域 ,强度减小 ;ICs异常对中高纬度地区降水的影响不可忽视 ,在某些地区 ,当其与某种 SST异常配置时 ,可能引起降水距平反向 ;热带东太平洋的 SST异常对全球的大气环流有着重要作用 ;相比之下 ,ICs异常的作用是局地的 ,却是重要的 ,对中高纬度地区的环流形势影响较大 .

By using IAP L2 AGCM 1 1, a series of extraseasonal sensitive experiments are made for two types of atmospheric initial conditions (ICs) anomalies and two types of sea surface temperature (SST) anomalies. The effects of the ICs anomalies and SST anomalies on 500 hPa geopotential height and precipitation during summer season (JJA) are investigated. The results show that SST anomalies have remarkable influence on the precipitation of JJA in China and nearby. When forced by El Nio type SST anomalies, the precipitation is below normal in the areas from Southwest China to North China and above normal from the southeast coast to Japan and the sea area to the east with positive intensity center over the ocean. Furthermore, when forced by La Nia type SST anomalies, the positive region moves westerly and northerly so that the positive center locates in the Yangtz River valley, but the intensity decreases. Meanwhile, the influence of ICs anomalies can not be neglected, especially in some regions and in the cases when combined with certain type of SST anomalies in which the pattern of precipitation would be totally different. In general, for general circulation motion, the effect of SST anomalies is global and determinant while that of ICs is local but important, especially in the middle and high latitude regions.