2011年我国夏季降水动力统计预测与异常成因  

Causes and Dynamic-statistical Forecast of the Summer Rainfall Anomaly over China in 2011

作　　者：赵俊虎[1,2] 杨杰[1] 封国林[2] 张世轩[1] 

机构地区：[1]兰州大学大气科学学院,兰州730000 [2]国家气候中心,北京100081

出　　处：《应用气象学报》2013年第1期43-54,共12页Journal of Applied Meteorological Science

基　　金：国家自然科学基金项目(40930952;41175067);"973"项目(2012CB955902);公益性行业(气象)科研专项(GYHY201106016)

摘　　要：该文对2011年我国夏季降水情况进行简要回顾,并对3月制作的夏季降水动力统计客观定量化和动力统计-诊断预测结果进行检验。以长江中下游地区为例,对比说明了两种预测方法选取因子的差异及动力统计-诊断较动力统计客观定量化预测结果有一定提高的原因。在此基础上,分析了导致2011年夏季主雨带较预测结果偏南的影响因素,并进一步探讨了大气环流特别是中高纬度阻塞高压和低纬度西太平洋副热带高压异常的可能成因。结果表明:2011年夏季主雨带偏南主要是中高纬度阻塞形势与低纬度副热带高压的季节内异常振荡及二者逐月不同配置的产物,而中高纬度阻塞形势与低纬度副热带高压的季节内异常振荡是由海温、积雪等外强迫及东亚环流系统内部成员相互作用所致。The large-scale rainfall over China in summer of 2011 is reviewed, the prediction results of dynamic- statistical objective quantitative （DSOQ） and dynamic-statistical diagnostic （DSD） methods are evaluated. Compared to the DSOQ, the anomaly correlation coefficient （ACC） and predictive score （PS） of which are 0.12 and 70, the DSD method has obvious advantage in predicting skill by increasing the ACC and PS to 0. 25 and 75, respectively. Taking the middle and lower reaches of the yo ngtze （MLRY） as an experiment region, the differences in predictive factors of these two methods are compared and the advantages of DSD method are analyzed. The probable causes of summer rainfall anomaly distribution in 2011 and the relevant circulation anomaly characteristics are also discussed, such as the blocking-high （BH） anomaly in middle- high latitudes and the western Pacific subtropical high （WPSH） anomaly in low latitudes. The results indi- cate that the abundant rainfall in June over the middle and lower reaches of the Yangtze and the uneven dis- tribution of June-July-August （JJA） rainfall are the direct causes for the southerly rainbelt in the summerof 2011. And this is related to the BH activities, the intra-seasonal oscillations （ISO） of WPSH and the monthly different configurations between them. In June, the atmospheric circulations reveal two trough areas and one ridge area at the middle-high latitudes. The intensity and western boundary of the WPSH are normal, while the latitude of the ridge line is northerly. The southward cold air behind the trough conver- ges with the northward warm wet airflow over MLRY, which causes substantial precipitation in this area. Compared with June, the atmospheric circulations in middle-high latitudes change into the two ridge areas and one trough area in July, the WPSH becomes weaker and its western boundary moves eastward, and the ridge line is more northward. These situations lead to stronger cold air than the warm wet airflow, re- sulting in droug

关 键 词：夏季降水 动力统计客观定量化 动力统计-诊断 环流异常 

分 类 号：P426.6[天文地球—大气科学及气象学]