Spirals on the sea
Spirals on the sea
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DOI：
10.1098/rspa.2000.0560
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发表时间：
2000-05-08
影响因子：
3.5
通讯作者：
Zachariasen, F
中科院分区：
文献类型：
--
作者：
Munk, W;Armi, L;Zachariasen, F
30年前，人们在阿波罗使命的阳光中首次看到了螺旋形漩涡;此后，它们被记录在合成孔径雷达（SAR）图像和红外线中。我们提供了一个小样本的图像。这些螺旋广泛分布于世界各大洋，大小为10至25公里，绝大多数是气旋性的。在有利于可视化的微风下，具有高表面活性剂密度和低表面粗糙度的线性表面特征是常见的。在水平剪切不稳定性相关的旋涡中，线性特征缠绕成螺旋，通过旋转进行修改，在剪切与科里奥利频率相当的区域中。提出了两种集中剪切模型：经典尖锐Margules锋面的软化版本，以及霍斯金斯和布雷瑟顿的随时间变化的拉格朗日模型。水平切变不稳定性和两种锋面模式都有利于气旋性切变和气旋性螺旋，但原因不同。
Spiral eddies were first seen in the sunglitter on the Apollo Mission 30 years ago; they have since been recorded on synthetic aperture radar (SAR) images and in the infrared. We present a small sample of images. The spirals are broadly distributed over the world's oceans, 10-25 km in size and overwhelmingly cyclonic. Under light winds favourable to visualization, linear surface features with high surfactant density and low surface roughness are of common occurrence. The linear features are wound into spirals in vortices associated with horizontal shear instability, modified by rotation, in regions where the shear is comparable with the Coriolis frequency. Two models for concentrating shear are presented: a softened version of the classical sharp Margules front, and the time-dependent Lagrangian model of Hoskins & Bretherton. Horizontal shear instabilities and both frontal models favour cyclonic shear and cyclonic spirals, but for different reasons.