利用1979—2012年西北太平洋热带气旋最佳路径资料,Hadley中心的海温资料和NCEP/NCAR再分析资料等,研究了夏季(6—10月)热带北大西洋海温异常与西北太平洋热带气旋(Tropical Cyclone,TC)生成的关系及其可能机制。结果表明,夏季热带北大西洋海温异常与同期西北太平洋TC生成频次之间存在显著的负相关关系。热带北大西洋海温的异常增暖可产生一对东—西向分布的偶极型低层异常环流,其中气旋性异常环流位于北大西洋/东太平洋地区,反气旋异常环流位于西北太平洋地区。该反气旋环流异常使得TC主要生成区的对流活动受到抑制、低层涡度正异常、中低层相对湿度负异常、中层下沉气流异常,这些动力/热力条件均不利于TC生成。此外,西北太平洋地区低层涡旋动能负异常,同时来自大尺度环流的涡旋动能的正压转换也受到抑制,不能为TC的生成和发展提供额外能量源。反之亦然。
The influences of sea surface temperature( SST) anomaly in the North tropical Atlantic( NTA) during boreal summer( June-October) on tropical cyclone( TC) formation over the w estern North Pacific( WNP),and the underlying physical mechanisms are investigated using TC best track data sets,Hadley SST data and NCEP / NCAR reanalysis data for the period of 1979—2012. A significant negative correlation betw een WNP TC genesis frequency and simultaneous June-October NTA SST anomalies are demonstrated. The results suggest that the NTA SST w arming produces a pair of low-level anomalous circulations,w ith an anomalous cyclonic circulation over the tropical Atlantic / eastern Pacific,and an anomalous anticyclonic circulation over the WNP. This anticyclonic circulation anomaly suppresses convection and barotropic energy conversion from large-scale flow,reduces low-level cyclonic vorticity and midtropospheric humidity,thus greatly inhibits the TC genesis over the WNP; and vice versa.