Wintertime Wind Forcing and Sea Surface Cooling Near the South India Tip Observed Using NSCAT and AVHRR
Wintertime Wind Forcing and Sea Surface Cooling Near the South India Tip Observed Using NSCAT and AVHRR
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DOI：
10.1016/s0034-4257(00)00081-x
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发表时间：
2000-07
影响因子：
13.5
通讯作者：
A. J. Luis;H. Kawamura
中科院分区：
文献类型：
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作者：
A. J. Luis;H. Kawamura
本报告讨论了1996-1997年冬季季风在靠近印度尖端的马纳尔湾的地形海气相互作用的一个例子。利用高空间分辨率NASA-Scatterometer （NSCAT）的风数据，在冬季季风高峰期确定了墨西哥湾1°×1°的强风区域。南印度和斯里兰卡特有的地形及其朝向季风的方向倾向于引导这种强风。利用NSCAT风和欧洲中期天气预报中心客观分析地面数据的海气热通量分析表明，1月份强烈的冬季季风爆发导致以7.5°N， 77.5°E为中心的取风区大量潜热损失（180 W/m2）。弱的海气温度梯度导致来自海洋的弱感热损失（<15 W/m2）。海洋对这一强迫的响应是利用每周和每月的卫星平均海温（SST）图来检验的；这表明海面沿风向轴冷却了约1°C。这种冷却的副产品是沿强风应力区外围出现海温锋。地表气象的时间序列分析表明，这种强迫的周期约为15天，在12月的最后一周达到峰值。NSCAT风资料得出的风应力旋度在2周时间尺度上呈现高负值（反气旋Ekman泵送），伴有强风。在马纳尔湾观察到的特征与从其他一些地点报道的特征相似。
This report addresses a case of topographic air–sea interaction in the Gulf of Mannar, near the Indian tip, for the winter monsoon of 1996–1997. Using high spatial resolution NASA-Scatterometer (NSCAT) wind data, a 1°×1° region of strong wind is identified in the Gulf during the peak of the winter monsoon. The characteristic topography of South India and Sri Lanka and their orientation to the monsoon wind tend to channel this strong wind. Air–sea heat flux analyses, using the NSCAT wind and the European Center for Medium-Range Weather Forecast objective analyses surface data, reveal that the strong winter monsoon bursts cause large latent heat loss (180 W/m2) from a wind-fetch region centered on 7.5°N, 77.5°E during January. Weak air–sea temperature gradients result in weak sensible heat loss (<15 W/m2) from the ocean. The ocean response to this forcing is examined using weekly and monthly mean satellite-derived sea surface temperature (SST) maps; these indicate a sea surface cooling of about 1°C along the axis of the wind flow. A by-product of this cooling is an emergence of a SST front along the periphery of the strong wind-stress region. Time-series analyses of the surface meteorology reveal that this forcing has a periodicity of about 15 days, with a peak during the last week of December. Wind stress curl derived from the NSCAT wind data exhibits high negative values (anticyclonic Ekman pumping) on a 2-week time scale, concomitant with strong wind bursts. The features observed in the Gulf of Mannar are similar to those reported from some other locations.