Stratospheric entry point for upper-tropospheric air within the Asian summer monsoon anticyclone  

作　　者：FAN QiuJun BIAN JianChun Laura L.PAN 

机构地区：[1]Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China [2]College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China [3]National Center for Atmospheric Research, Boulder, CO 80301, USA

出　　处：《Science China Earth Sciences》2017年第9期1685-1693,共9页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 91337214 & 41675040)

摘　　要：The Asian summer monsoon(ASM) anticyclone isolates upper-tropospheric air within the interior of the anticyclone from the outside. Forward trajectory simulations in previous studies have shown that much of the air within the ASM anticyclone can be trapped for up to two or three weeks, not only laterally but also vertically. Here, we investigate the locations of exit points for upper-tropospheric air trapped within the ASM anticyclone, especially the preferred tropopause-crossing locations, using a 3-dimensional trajectory model. Forward trajectory calculations show two-thirds of the air crosses the tropopause at the southern part of the anticyclone via upward diabatic transport. Furthermore, some air crosses at northern and eastern parts via isentropic shedding, but air crosses rarely through the center of the anticyclone. However, calculations also show that many stratospheric parcels within the anticyclone are traceable from the upper-tropospheric anticyclone. This implies they cannot break through the tropopause directly overhead but instead enter the stratosphere via other entry points.The Asian summer monsoon（ASM） anticyclone isolates upper-tropospheric air within the interior of the anticyclone from the outside. Forward trajectory simulations in previous studies have shown that much of the air within the ASM anticyclone can be trapped for up to two or three weeks, not only laterally but also vertically. Here, we investigate the locations of exit points for upper-tropospheric air trapped within the ASM anticyclone, especially the preferred tropopause-crossing locations, using a 3-dimensional trajectory model. Forward trajectory calculations show two-thirds of the air crosses the tropopause at the southern part of the anticyclone via upward diabatic transport. Furthermore, some air crosses at northern and eastern parts via isentropic shedding, but air crosses rarely through the center of the anticyclone. However, calculations also show that many stratospheric parcels within the anticyclone are traceable from the upper-tropospheric anticyclone. This implies they cannot break through the tropopause directly overhead but instead enter the stratosphere via other entry points.

关 键 词：Asian summer monsoon anticyclone Tropopause Stratosphere-troposphere exchange Trajectory simulation 

分 类 号：P421[天文地球—大气科学及气象学]