An Enhanced Influence of Tropical Indian Ocean on the South Asia High after the Late 1970s
An Enhanced Influence of Tropical Indian Ocean on the South Asia High after the Late 1970s
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DOI：
10.1175/jcli-d-11-00696.1
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发表时间：
2012-04
影响因子：
4.9
通讯作者：
X. Qu;G. Huang
中科院分区：
文献类型：
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作者：
X. Qu;G. Huang
热带印度洋（TIO）对南亚高压（SAH）强度的影响在20世纪70年代后期经历了一个年代际变化，年代际变化后（前），影响显著（不显著）。本研究探讨对流层温度的作用，在中继海表温度（SST）的影响，SAH和TIO的影响的变化。在这两个时段中，局地对流层温度对TIO增暖的响应是明显的，其中第二时段的响应更为显著。这一变化可能是TIO对SAH影响增强的原因。令人鼓舞的是，集合模拟准确地捕捉到了年代际变化的时间，这表明增强的影响归因于SST强迫。TIO-SAH关系的变化可能有两个原因。第一个原因是TIO中SST异常位置的变化。在第二个时期，印度洋暖池存在海温正距平。海温异常通过背景强对流和湿调节对对流层温度产生重要影响，从而影响南亚高压。第二个原因是平均SST和SST变率的年代际变化。近几十年来，背景海温和TIO海温的变率都增加，增强了海温异常对大气的影响。还讨论了远程海洋强迫对增强的TIO-SAH关系的影响及其与TIO SST贡献的比较。
The tropical Indian Ocean (TIO)’s influence on the South Asia high (SAH)’s intensity experiences a decadal change in the late 1970s; after (before) the decadal shift, the influence is significant (insignificant). The present study investigates the role of tropospheric temperature in relaying the impact of sea surface temperature (SST) to the SAH and the change in the TIO’s influence. During the two epochs, the local tropospheric temperature responses to the TIO warming are distinct—more significant during the second epoch. It is inferred that this change may be responsible for the strengthening of the TIO’s influence on the SAH. Encouragingly, the ensemble simulations accurately capture the time of the decadal change, indicating that the enhanced influence is attributed to the SST forcing. There are two possible reasons for the change in the TIO‐SAH relationship. The first reason is the change in the locations of the SST anomalies in the TIO. During the second epoch, positive SST anomalies lie in the Indian Ocean warm pool. Through the background vigorous convection and moist adjustment, the SST anomalies affect largely the tropospheric temperature and thus the SAH. The second reason is the decadal change in mean SST and the SST variability. During the recent decades, both the background SST and the variability of the TIO SST increase, which enhance the influence of the SST anomalies on the atmosphere. The influence of the remote oceanic forcing on the enhanced TIO‐SAH relationship and its comparison with the contribution of the TIO SST are also discussed.