Through observational analyses, an inter-hemispheric teleconnection is identified between the subtropical region of the South China Sea to the western Pacific near the Philippines （WP） and the region to the east of Australia （AE）. The teleconnection is significantly correlated with sea surface temperature anomalies （SSTAs） in key sea areas （including the Indian Ocean, the South China Sea, and the area to the east of Australia）. Based on the IAP T42L9 model, numerical experiments axe performed to explore a possible mechanism for the formation of the teleconnection. The results show that the positive SST anomalies in the key sea areas may jointly contribute to the occurrence and maintenance of the positive geopotential height anomalies over both the WP and AE and be a critical factor in the teleconnection formation. The large-scale SST anomaly in the Indian Ocean, involving the tropics concurrent atmospheric responses over both the WP and the east of Australia seems to reinforce and maintain the and subtropics of both hemispheres, may lead to AE, while the effect of the local SST anomaly to positive height anomaly over the AE.
利用集合预报成员初值误差在大气相空间中增长方向不同的特点,结合模式检验方法,构建持续性强降水可预报性评估指数(Index of Composite Predictability,ICP),为持续性强降水可预报性及数值预报误差增长机理研究提供科学方法。ICP综合评估指数包括三个数学模型:集合预报成员单一评估指数定义、集合预报成员综合评估指数定义和集合预报成员预报能力定义。利用中国国家气象中心T213全球集合预报资料,选取江淮流域2010年6月17—25日和2011年6月4—12日2次持续性强降水过程,进行ICP综合评估指数应用试验,其中,单一评估指数选取中雨公平成功指数ETS、500 hPa高度场均方根误差分别代表模式降水预报能力和环流形势预报能力。结果显示:可预报性评估指数ICP可有效挑选出预报最好和最差的集合预报成员,两者对持续性强降水过程的大尺度环流系统、中尺度影响系统、降水过程预报差异显著,预报最好成员对影响持续性强降水的大尺度环流形势(阻塞高压、西太平洋副热带高压和东亚大槽)的位置和强度及演变过程、低层中尺度影响系统(如切变线和西南低涡)发生发展过程预报,以及降水发生时间和落区预报与实况更接近,预报更成功,持续性强降水可预报性综合评估指数ICP合理可靠。
