Regional Patterns of Tropical Indo-Pacific Climate Change: Evidence of the Walker Circulation Weakening
Regional Patterns of Tropical Indo-Pacific Climate Change: Evidence of the Walker Circulation Weakening
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DOI：
10.1175/jcli-d-11-00263.1
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发表时间：
2012-03-01
影响因子：
4.9
通讯作者：
Okumura, Yuko M.
中科院分区：
文献类型：
--
作者：
Tokinaga, Hiroki;Xie, Shang-Ping;Okumura, Yuko M.
热带印度洋-太平洋气候变化的区域模式研究在过去的六十年中，基于现场观测和海洋模式模拟的综合，重点是海表温度（SST），云，海平面气压（SLP），表面风和次表层海洋温度之间的物理一致性。一个新开发的偏差校正的地面风数据集显示西风趋势在热带太平洋西部和东风趋势在热带印度洋，表明步行者流通放缓。这种风的变化模式是一致的，所观察到的SLP的变化，表现出积极的趋势，在海洋大陆和赤道太平洋中部的负趋势。海洋大陆上空的水汽辐合被抑制主要是由于地面风的变化，导致观测到的海洋云量和陆地降水减少，此外，观测到的海洋混合层温度表明热带印度洋-太平洋的纬向对比度降低，其特征是热带东太平洋和西印度洋的变暖幅度大于热带西太平洋和东印度洋。类似的变化成功地模拟了海洋环流模式强迫偏置校正的风应力。而主要的SST重建的结果表明，在热带印度洋-太平洋的纬向梯度没有显着的变化，桶采样SST和夜间海洋气温（NMAT）显示减弱的纬向梯度与次表层温度的变化一致。所有这些来自独立观测的发现都为过去60年来与步行者环流减少有关的海洋-大气耦合提供了强有力的证据。
Regional patterns of tropical Indo-Pacific climate change are investigated over the last six decades based on a synthesis of in situ observations and ocean model simulations, with a focus on physical consistency among sea surface temperature (SST), cloud, sea level pressure (SLP), surface wind, and subsurface ocean temperature. A newly developed bias-corrected surface wind dataset displays westerly trends over the western tropical Pacific and easterly trends over the tropical Indian Ocean, indicative of a slowdown of the Walker circulation. This pattern of wind change is consistent with that of observed SLP change showing positive trends over the Maritime Continent and negative trends over the central equatorial Pacific. Suppressed moisture convergence over the Maritime Continent is largely due to surface wind changes, contributing to observed decreases in marine cloudiness and land precipitation there.Furthermore, observed ocean mixed layer temperatures indicate a reduction in zonal contrast in the tropical Indo-Pacific characterized by larger warming in the tropical eastern Pacific and western Indian Ocean than in the tropical western Pacific and eastern Indian Ocean. Similar changes are successfully simulated by an ocean general circulation model forced with the bias-corrected wind stress. Whereas results from major SST reconstructions show no significant change in zonal gradient in the tropical Indo-Pacific, both bucket-sampled SSTs and nighttime marine air temperatures (NMAT) show a weakening of the zonal gradient consistent with the subsurface temperature changes. All these findings from independent observations provide robust evidence for ocean-atmosphere coupling associated with the reduction in the Walker circulation over the last six decades.