Mechanism of thermal features over the Indo-China peninsula and possible effects on the onset of the South China sea monsoon
Mechanism of thermal features over the Indo-China peninsula and possible effects on the onset of the South China sea monsoon
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DOI：
10.1007/s00376-002-0053-5
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发表时间：
2002-09
影响因子：
5.8
通讯作者：
Zhang Yao-cun;Qian Yongfu
中科院分区：
文献类型：
--
作者：
Zhang Yao-cun;Qian Yongfu
利用1998年5月1日至8月31日的南海中国再分析资料和1980年1月至1995年12月的NCEP/NCAR候平均再分析资料，分析了位于印度支那-中国半岛附近的南海夏季风爆发期间的热特征。研究了中南半岛-中国半岛附近热力异常与南海季风爆发的可能关系，并对南海夏季风爆发的机制进行了探讨。1998年南海再分析资料表明，南海季风爆发前，中南半岛-中国半岛附近存在较强的持续性地面感热，具有明显的低频振荡特征。这种敏感的平移使中南半岛附近的低层大气中心变暖，局地水平温度和位势高度梯度较强，有利于中南半岛西南风的加强。低层出现较强的辐合风，高层出现较强的辐散风，为垂直运动的发展、降水的增强和南海季风的爆发提供了有利的位形。这些结果可以通过对多年平均数据的分析得到验证。此外，在南海季风爆发前，印支-中国半岛850hPa的增温速度比南中国海的增温速度更快，导致了印支-中国半岛与南中国海之间的温差增大。此外，经向温度和位势高度差的分析结果表明，南海季风爆发期间，副热带高压在印度洋-中国半岛的东撤与印度支那-中国半岛的增温和孟加拉湾低槽的东延有关。
The thermal characteristics during the South China Sea (SCS) summer monsoon onset period near the Indo-China Peninsula are analyzed by using the South China Sea Monsoon Experiment (SCSMEX) reanalysis data from 1 May to 31 August 1998 and the NCEP/ NCAR pentad-mean reanalysis data from January 1980 to December 1995. The possible relationships between the anomaly of thermal features near the Indo-China Peninsula and the SCS monsoon onset are investigated, and the mechanism causing the SCS summer monsoon onset is also discussed. Results from the 1998 SCSMEX reanalysis data show that there exists a strong persistent surface sensible heating near the Indo-China Peninsula prior to the SCS monsoon onset, which has apparent low frequency oscillation features. This sensible healing leads lo a warmer center in the lower atmosphere near the Indo-China Peninsula and strong local horizontal temperature and geopotential height gradients which are favorable to strengthening the southwest wind over the Indo-China Peninsula. It is also found that stronger convergent winds at lower levels and stronger divergent winds at high levels appear, which provide a favorable configuration for the development of vertical motion, enhancement of precipitation, and onset of the SCS monsoon. These results can be verified by analysis of the multi-year mean data. Additionally, it is found that the temperature at 850 hPa increases more rapidly over the Indo-China Peninsula than the South China Sea prior to the SCS monsoon onset, which leads to a strengthening of the temperature difference between the Indo-China Peninsula and the South China Sea. Moreover, results from the analysis of the longitudinal temperature and geopotential height differences show that the eastern retreat of the subtropical high over the Indo-China Peninsula during the period of SCS monsoon onset is associated with the temperature increase over the Indo-China Peninsula and the eastern extension of low trough over the Bay of Bengal.