Summer upwelling in the South China Sea and its role in regional climate variations
Summer upwelling in the South China Sea and its role in regional climate variations
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DOI：
10.1029/2003jc001867
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发表时间：
2003-08
影响因子：
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通讯作者：
S. Xie;Q. Xie;Dongxiao Wang;W. Liu
中科院分区：
文献类型：
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作者：
S. Xie;Q. Xie;Dongxiao Wang;W. Liu
利用一套新的卫星观测资料，研究了越南南部沿海夏季上升流的季节和年际变化以及冷水的离岸传播。在夏季，西南风冲击安南山脉（印度支那东海岸的南北走向山脉），在西贡以东的南端近海出现强风急流，导致强风卷曲，这对海岸外的海洋涌升非常重要。在7月和8月，一个反气旋性的海洋涡旋向东南发展，将近海的冷海水平流输送到开放的南海（SCS）。这条冷丝的中心始终位于风速最大值的北部，表明开阔海洋的上升流有助于冷却海洋表面。在海洋颜色观测中发现了冷丝的确凿证据，揭示了高叶绿素浓度的并置舌头。这条冷丝的发展破坏了南海夏季的增暖，并导致了明显的海温半年周期。此外，冷丝是南海夏季年际变化的重要参与者。在1998年，冷丝和仲夏冷却从未发生，引起了强烈的流域范围内的表面变暖。年际SST变化在气候冷丝上有一个局部极大值，且远大于邻近印度洋和西太平洋的变化。构造了一个冷丝指数，它与赤道东太平洋和印度洋海温有显著的滞后相关，表明厄尔尼诺的遥相关。
Seasonal and interannual variations of summer upwelling off the South Vietnam coast and the offshore spread of cold water are investigated using a suite of new satellite measurements. In summer, as the southwesterly winds impinge on Annam Cordillera (a north-south running mountain range on the east coast of Indochina) a strong wind jet occurs at its southern tip offshore east of Saigon, resulting in strong wind curls that are important for ocean upwelling off the coast. In July and August an anticyclonic ocean eddy develops to the southeast, advecting the cold coastal water offshore into the open South China Sea (SCS). The center of this cold filament is located consistently north of the wind speed maximum, indicating that open-ocean upwelling helps to cool the ocean surface. Corroborating evidence for the cold filament is found in ocean color observations that reveal a collocated tongue of high chlorophyll concentration. The development of this cold filament disrupts the summer warming of the SCS and causes a pronounced semiannual cycle in SST. Moreover, the cold filament is an important player in interannual variability in the summer SCS. In 1998, the cold filament and mid-summer cooling never took place, giving rise to a strong basin-wide surface warming. Interannual SST variance has a local maximum over the climatological cold filament, and is much greater than the variance over the adjacent Indian and western Pacific Oceans. A cold filament index is constructed, which displays significant lagged correlation with SST in the eastern equatorial Pacific and Indian Oceans, indicative of a teleconnection from El Nino.