Vertical Circulation Structure, Interannual Variation Features and Variation Mechanism of Western Pacific Subtropical High  

关于西太平洋副热带高压的垂直环流结构和年际变动特征及其机制研究(英文)

作　　者：何金海 周兵 温敏 李峰 

机构地区：[1]Nanfing Institute of Meteorology. [2]LASG, lnstitute of Atmnospheric Physics, Chinese Academy of Sciences, [3]Nanjing Institute of Meteorology,

出　　处：《Advances in Atmospheric Sciences》2001年第4期497-510,共14页大气科学进展（英文版）

基　　金：The National Natural Science Foundation of China (No.49635170);The program of Study on Regional Climate Variation and Mechani

摘　　要：The paper investigates the vertical circulation structure of the western Pacific subtropical high (STH) and its interannual variation features in relation tO East Asian subtropical summer monsoon and external thermal forcing by using the high-resolution and good-quality observations from the 1998 South China Sea Summer Monsoon Experiment (SCSMEX), the NCEP 40-year reanalysis data and relevant SST and the STH parameters. It is found that the vertical circulation structures differ greatly in features between quasi-Stationary and transient components of the western Pacific STH. When rainstorms happen in the rainband of East Asian subtropical monsoon on the STH north side, the downdrafts are distinct around the ridge at a related meridian. The sinking at high (low) levels comes from the north (south) side of the STH, thereby revealing that the high is a tie between tropical and extratropical systems. The analyses of this paper suggest that the latent heat release associated with subtropical monsoon precipitation, the offshore SST and East Asian land-sea thermal contrast have a significant effect on the STH interannual anomaly. Our numerical experiment shows that the offshore SSTA-caused sensible heating may excite an anomalous anticyclonic circulation on the west side, which affects the intensity (area) and meridional position of the western Pacific STH.The paper investigates the vertical circulation structure of the western Pacific subtropical high (STH) and its interannual variation features in relation tO East Asian subtropical summer monsoon and external thermal forcing by using the high-resolution and good-quality observations from the 1998 South China Sea Summer Monsoon Experiment (SCSMEX), the NCEP 40-year reanalysis data and relevant SST and the STH parameters. It is found that the vertical circulation structures differ greatly in features between quasi-Stationary and transient components of the western Pacific STH. When rainstorms happen in the rainband of East Asian subtropical monsoon on the STH north side, the downdrafts are distinct around the ridge at a related meridian. The sinking at high (low) levels comes from the north (south) side of the STH, thereby revealing that the high is a tie between tropical and extratropical systems. The analyses of this paper suggest that the latent heat release associated with subtropical monsoon precipitation, the offshore SST and East Asian land-sea thermal contrast have a significant effect on the STH interannual anomaly. Our numerical experiment shows that the offshore SSTA-caused sensible heating may excite an anomalous anticyclonic circulation on the west side, which affects the intensity (area) and meridional position of the western Pacific STH.

关 键 词：Western Pacific subtropical high. Meridional/zonal circulation Interannual variation Offshore sea surface tomperature 

分 类 号：P433[天文地球—大气科学及气象学]