| STUDY ON THE VARIATION IN THE CONFIGURATION OF SUBTROPICAL ANTICYCLONE AND ITS MECHANISM DURING SEASONAL TRANSITION-PART Ⅱ:SEASONAL TRANSITION INDICES OVER THE ASIAN MONSOON REGION |
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| 作者姓名： | MAO Jiangyu WU Guoxiong LIU Yimin |
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| 作者单位： | LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 |
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| 基金项目： | This work is jointly supported by the National Natural Science Foundation of China (40375022,40135020);Chinese Academy of Sciences (ZKCX2-SW-210);LASG Foundation (40023001) |
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| 摘 要： | Based on the studies in Part Ⅰ (see Mao et al.2003),this paper further examines the relationship between the Asian summer monsoon onset and variation in meridional position of the warm temperature ridge with a zonal orientation in mid-upper troposphere.During the Asian monsoon bursting consequentially over the Bay of Bengal,South China Sea,and South Asia,in addition to the reversal of winds in the lower and upper troposphere and deep convection before and after the onset,the atmospheric meridional temperature gradient (MTG) in the vicinity of the ridge-surface of subtropical high (WEB defined in Part Ⅰ) exhibits a significant reversal.Since the establishment of temperature structure with higher over north than over south of the WEB in the mid-upper troposphere (200-500 hPa) characterizes the collective essential that the Asian summer monsoon bursts over different areas,the MTG in mid-upper troposphere,based on the thermodynamics associated with the seasonal transition,should be a reasonable index to measure the Asian monsoon onset.The definition for onset date is proposed,and the time series of onset date for different sections are determined.As compared with the onset dates determined by other indices such as 850-hPa zonal wind and OLR.correlation analyses indicate that the 850-hPa zonal wind is only regional index,but the MTG index is applicable universally to the Asian monsoon regime.
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| 收稿时间： | 2003/10/15 0:00:00 |
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