Warm outbreaks of the Gulf Stream into the Sargasso Sea
Warm outbreaks of the Gulf Stream into the Sargasso Sea
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墨西哥湾流温暖爆发进入马尾藻海
DOI：
10.1029/jc091ic05p06583
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
W. Large
中科院分区：
文献类型：
--
作者：
P. Cornillon;David J. Evans;W. Large
暖爆发是指墨西哥湾流中的大量水体，具有明显的反气旋环流，从墨西哥湾流中分离出来，并在马尾藻海中作为一个明确的实体存在。由于温暖爆发在表面比马尾藻海水温暖，它们通常在卫星热红外图像中清晰可见。根据对750多幅卫星图像的调查，这些图像覆盖了墨西哥湾流以南64°至74°W之间的马尾藻海，时间跨度为5年，观察到18种可能的爆发。所有气旋都在西经65°以西形成，大部分在西经67°至72°之间形成。18个中有5个被观察到完全脱离墨西哥湾流，并具有以下共同特性：（1）它们都是在墨西哥湾流大弯曲的最大气旋曲率点或附近的几天内形成的，（2）表面表达相对短暂，大约10到20天，（3）它们（以及其他13个）的尺寸约为100 × 200公里。由于暖爆发的特征与Ikeda和Apel（1981）从一个向东流动的急流的两层准地转模式中预测的“反向涡旋”的特征相似，我们认为这两种现象是相关的。这一假设的进一步支持是，每年两到六次暖爆发的形成率与该地区一次性深海温度计调查中观察到的反气旋涡旋相似。
A warm outbreak is a large body of Gulf Stream water with apparent anticyclonic circulation that detaches from the Gulf Stream and exists as a well-defined entity in the Sargasso Sea. Because warm outbreaks are warmer at the surface than Sargasso Sea water, they are often clearly visible in satellite thermal infrared imagery. From a survey of over 750 satellite images covering the Sargasso Sea immediately to the south of the Gulf Stream between 64° and 74°W and spanning a 5-year period, 18 possible outbreaks have been observed. All formed west of 65°W, with the majority forming between 67° and 72°W. Five of the 18 were observed to detach completely from the Gulf Stream and have the following properties in common: (1) they all formed in several days at or near the point of maximum cyclonic curvature of a large Gulf Stream meander, (2) the surface expression was relatively short-lived, of the order of 10 to 20 days, and (3) their dimensions (and those of the other 13) were of the order of 100 by 200 km. Given the similarity between the characteristics of warm outbreaks and those of “opposite vortices” predicted by Ikeda and Apel (1981) from a two-layer, quasi-geostrophic model of an eastward flowing jet, it is suggested that the two phenomena are related. Further support of this hypothesis is the fact that the rate of formation of warm outbreaks, between two and six per year, is similar to that of anticyclonic eddies observed in expendable bathythermograph surveys of this area.