基于SAR多普勒质心频移的海面流场迭代反演算法

秦艳萍; 范陈清; 张玉滨

doi:10.12284/hyxb2022007

基于SAR多普勒质心频移的海面流场迭代反演算法

doi: 10.12284/hyxb2022007

1.
中国海洋大学信息科学与工程学院，山东青岛 266100
2.
自然资源部第一海洋研究所，山东青岛 266061

基金项目: 国家重点研发计划（2017YFC1405602）；国家自然科学基金（62031005，U2006207，41906157）

详细信息

作者简介:
秦艳萍（1996-），女，山东省潍坊市人，主要从事海洋遥感方向研究。E-mail：qyp3822@stu.ouc.edu.cn

通讯作者:
张玉滨，男，讲师，主要从事海洋遥感方向研究。E-mail：zhangyb@ouc.edu.cn

中图分类号: P731.21；P715.7
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出版历程
- 收稿日期: 2020-12-31
- 修回日期: 2021-11-01
- 刊出日期: 2022-03-18

An iterative retrieval algorithm of ocean surface current based on SAR Doppler centroid anomaly

1.
College of Information Science and Engineering, Ocean University of China, Qingdao 266100, China
2.
First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, China

摘要

摘要: 为了克服SAR多普勒质心频移法反演海面流场时风场贡献去除困难的难题，本文提出了基于M4S模型的弦截下山法，利用其迭代计算局部区域的海面流场；然后估算整幅SAR图像中风场对多普勒速度的风贡献因子$\gamma $；最后去除风场对多普勒速度的贡献。将该算法用于Radarsat-2数据反演海面径向流速，并利用匹配的实测数据验证反演精度。研究结果表明，本文提出的弦截下山法具有良好的收敛性和较高的收敛速度，而且对本文中使用的两景SAR数据，反演的海面径向流速偏差分别为0.04 m/s和0.15 m/s。
- SAR /
- 多普勒质心频移法 /
- 海面流场 /
- 弦截下山法
Abstract: To overcome the difficulty of removing the wind field contribution in the SAR Doppler centroid anomaly method when retrieving the ocean surface current, in this paper, a secant downhill method based on the M4S model is proposed. The contribution of the wind field is removed by iteratively calculating the sea surface current field in a local area and subsequently estimating the wind contribution factor to the Doppler velocity of the whole SAR map. Our method is used to retrieve the radial velocity of sea surface from Radarsat-2 data. Its retrieval accuracy is verified by matching measured data. The results show that the proposed method not only can possess well convergence and high convergent speed, but also the deviation of the radial velocity of the surface is 0.04 m/s and 0.15 m/s respectively for two scene SAR data used in this paper.
- SAR /
- Doppler centroid anomaly /
- ocean surface current /
- secant downhill method

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图 1 所用Radarsat-2 SAR 数据覆盖区域

a. 2019年6月23日；b. 2019年6月25日

Fig. 1 Coverage area of Radarsat-2 SAR data

a. June 23, 2019; b. June 25, 2019

下载: 全尺寸图片幻灯片

图 2 弦截下山法迭代反演流场流程

Fig. 2 Flow chart of iterative retrieval of current field by secant downhill method

下载: 全尺寸图片幻灯片

图 3 2019年6月23日SAR图像反演结果

a. 实测多普勒中心频率f_Dc；b. 预测多普勒中心频率f_Dp；c. 多普勒质心频率异常值f_Dca；d. 地距多普勒速度V_{dop_sar}，其中红框区域为利用弦截下山法迭代反演流场的局部区域

Fig. 3 SAR image retrieval results on June 23, 2019

a. Measured Doppler center frequency f_Dc; b. predicted Doppler center frequency f_Dp; c. Doppler centroid frequency anomaly f_Dca; d. ground Doppler velocity V_{dop_sar}, the red box area is the local area of the current field iteratively retrieved by the secant downhill method

下载: 全尺寸图片幻灯片

图 4 2019年6月25日SAR数据反演的地距多普勒速度V_{dop_car}

Fig. 4 Ground range Doppler velocity retrieved from SAR data on June 25, 2019

下载: 全尺寸图片幻灯片

图 5 两景SAR数据对应的海表面径向流速

a. 2019年6月23日；b. 2019年6月25日。黑色五角星处是实测数据所在位置

Fig. 5 The radial velocity of the sea surface corresponding to the SAR data of the two scenes

a. June 23, 2019; b. June 25, 2019. The black five-pointed star is the location of the measured data

下载: 全尺寸图片幻灯片

表 1 本文所用Radarsat-2 SAR数据信息

Tab. 1 Radarsat-2 SAR data information used in this paper

成像时间（UTC）	幅宽/km	分辨率/m	入射角范围/（°）	极化方式	升、降轨模式
2019年6月23日21时53分	102.52×109.43	4.92×11.83	41.45～46.70	垂直极化（VV）	降轨
2019年6月25日10时11分	102.91×109.93	5.04×11.83	33.51～39.74	垂直极化（VV）	升轨

下载: 导出CSV

表 2 海流计实测海流数据

Tab. 2 Current data measured by ocean current meters

测量时间（UTC）	位置	平均流速/（m·s^–1）	平均流向/（°）	实测数据在SAR视向方向的分量/（m·s^–1）
2019年6月23日21时48–58分	21.30°N，118.51°E	0.42	336.70	0.23
2019年6月25日10时6–16分	21.80°N，118.29°E	0.15	283.90	–0.14

下载: 导出CSV

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