Abstract

An objective wavelet based algorithm has been developed to find the orientation of rolls in Synthetic Aperture Radar (SAR) imagery using Radar Imaging Satellite (RISAT-1) data. The orientation of rolls plays a very crucial role for the estimation of ocean surface wind direction. It also affects the shape and size of a tropical cyclone. In this manuscript, SAR image was decomposed using Haar Wavelet Transform (HWT) and optimal thresholding was done to delineate the direction of propagating rolls. The roll features were found oriented in the range 26°–31° from the along track direction. These features are very useful to retrieve wind direction and hence the vector wind observation over the ocean surface.

Highlights

1. 1.

   Development of a new algorithm to find the orientation of MABL rolls in the SAR imagery.

2. 2.

   Use of Haar Wavelet Transform due to its high computational efficiency and ease of potential operational application.

3. 3.

   The study is first of its kind over the Indian Ocean.

4. 4.

   Rolls are oriented between 26° to 31° from the along track direction.

中文翻译：

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基于小波变换的SAR图像海洋大气滚动方向定位：以孟加拉湾为例

摘要

已经开发了一种基于小波的客观算法，可以使用雷达成像卫星（RISAT-1）数据在合成孔径雷达（SAR）图像中找到滚动方向。轧辊的方向对于估算海洋表面风向起着至关重要的作用。它还会影响热带气旋的形状和大小。在该手稿中，SAR图像使用Haar小波变换（HWT）进行了分解，并进行了最佳阈值划分来描述传播辊的方向。轧辊特征被确定为沿轨道方向在26°–31°范围内。这些特征对于检索风向非常有用，因此对海洋表面的矢量风观测也非常有用。

强调

1. 1。

   开发了一种新的算法来查找SAR图像中MABL辊的方向。

2. 2。

   使用Haar小波变换的原因在于其计算效率高且易于潜在的操作应用。

3. 3。

   该研究是印度洋上的同类研究。

4. 4。

   轧辊的方向与轨道方向之间的夹角为26°至31°。