Air-Sea Coupled Process Involved in Stepwise Seasonal Evolution of the Asian Summer Monsoon
Air-Sea Coupled Process Involved in Stepwise Seasonal Evolution of the Asian Summer Monsoon
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DOI：
10.4157/grj.78.825
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发表时间：
2005-10
影响因子：
3.2
通讯作者：
H. Ueda
中科院分区：
文献类型：
--
作者：
H. Ueda
观测证据表明亚洲夏季风（ASM）和西太平洋季风（WPM）成熟过程中存在大气-海洋耦合系统。 ASM和WPM的特点是四个突然的季节变化，在年周期中表现出锁相特征。它们对应于 ASM 的第一次过渡（5 月中旬）；印度季风爆发（六月初）；菲律宾东部 ITCZ 成熟期（6 月中旬），对流跳跃在 150°E 附近（7 月下旬）。超过 29.0°C 的暖池的出现是了解 ASM 和 WPM 次季节演变的关键要素之一。在印度洋，海面温度（SST）随着太阳照射和蒸发冷却的减少而季节性增加。相比之下，副热带西太平洋（SWP）海温上升较印度洋晚约1个月。 SWP海洋表面的热通量分析表明，变暖的延迟归因于蒸发冷却的减少，这与热带东风的减弱有关，而热带东风的减弱与季风西风向东扩展（____150°E）同时发生。这些过程对于年际波动也有效；也就是说，增强的反夏季风可以在南风波上诱发暖海温异常。因此，这些物理解释表明 WPM 可预测性进一步增加。
Observational evidence is presented to show an atmosphere-ocean coupled system in the maturing process of the Asian summer monsoon (ASM) and the western Pacific monsoon (WPM). The ASM and WPM are characterized by four abrupt seasonal changes that exhibit phase-locking features in the annual cycle. They correspond to the first transition of the ASM (mid May); the Indian monsoon onset (early June); the mature phase of ITCZ (mid June) to the east of Philippines and convection jump around 150°E (late July). The appearance of a warm pool, in excess of 29.0°C, is one of the key elements in understanding the sub-seasonal evolution of the ASM and WPM. Over the Indian Ocean, the seasonal increase of sea surface temperature (SST) follows the solar insolation and reduced evaporative cooling as well. In contrast, increase of SST over the subtropical western Pacific (SWP) lags behind those in the Indian Ocean by about one month. The heat flux analysis at the ocean surface in the SWP reveals that the delayed warming is attributed to reduced evaporative cooling, in relation to the weakening of the tropical easterlies, which is concurrent with the eastward expansion (_??_150°E) of the monsoon westerlies. These processes are also valid for interannual fluctuation; namely, the intensified ASM can induce warm SST anomalies over the SWP. Thus, these physical interpretations suggest further increase of the WPM predictability.