Multi-stage onset of the summer monsoon over the western North Pacific
Multi-stage onset of the summer monsoon over the western North Pacific
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DOI：
10.1007/s003820000118
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发表时间：
2001-02
期刊：
影响因子：
4.6
通讯作者：
R. Wu;Bin Wang
中科院分区：
文献类型：
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作者：
R. Wu;Bin Wang
夏季风爆发在南海和北太平洋西部（110 °~160 ° E，10 °~20 ° N）有明显的阶梯式东北向运动。季风雨在5月中旬开始在南海-菲律宾地区，突然延伸到西南菲律宾海在6月初至中旬，最后渗透到东北部的域在7月中旬左右。在关联中，在大气环流中确定了三个突变。在这三个阶段的初期，西北太平洋副高突然东退或迅速北移，季风槽突然东推或东北推。爆发的阶段性移动是大尺度环流向东北方向缓慢演变和季节内振荡（ISO）锁相的结果。季节演变为对流的发展提供了大尺度背景，ISO触发了深对流。西太平洋上空的ISO有一个约20 - 30天的优势期。这决定了季风爆发连续阶段之间的时间间隔。从大气的角度来看，在WNP的季节性海表温度（SST）的变化起着至关重要的作用，在东北推进的爆发。最暖舌（SST> 29.5 ° C）的季节性东北推进有利于季风槽和高对流不稳定区的东北移动。季风通过云辐射和风蒸发的反馈作用，对季节性海温变化产生影响。
The climatological summer monsoon onset displays a distinct step wise northeastward movement over the South China Sea and the western North Pacific (WNP) (110°–160°E, 10°–20°N). Monsoon rain commences over the South China Sea-Philippines region in mid-May, extends abruptly to the southwestern Philippine Sea in early to mid-June, and finally penetrates to the northeastern part of the domain around mid-July. In association, three abrupt changes are identified in the atmospheric circulation. Specifically, the WNP subtropical high displays a sudden eastward retreat or quick northward displacement and the monsoon trough pushes abruptly eastward or northeastward at the onset of the three stages. The step wise movement of the onset results from the slow northeastward seasonal evolution of large-scale circulation and the phase-locked intraseasonal oscillation (ISO). The seasonal evolution establishes a large-scale background for the development of convection and the ISO triggers deep convection. The ISO over the WNP has a dominant period of about 20–30 days. This determines up the time interval between the consecutive stages of the monsoon onset. From the atmospheric perspective, the seasonal sea surface temperature (SST) change in the WNP plays a critical role in the northeastward advance of the onset. The seasonal northeastward march of the warmest SST tongue (SST exceeding 29.5 °C) favors the northeastward movement of the monsoon trough and the high convective instability region. The seasonal SST change, in turn, is affected by the monsoon through cloud-radiation and wind-evaporation feedbacks.