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摘要: 海洋涡旋对海洋热循环起着关键作用，是海洋科学研究中的一个重要分支。合成孔径雷达(Synthetic Aperture Radar, SAR)为海洋涡旋的观测和研究提供了大量的图像数据，但是涡旋在SAR成像时会受到各种海洋环境因素的影响，难以解译涡旋SAR图像特征。仿真SAR图像可以用于研究涡旋的特征，但是目前极少有关于涡旋SAR图像仿真方法的研究。为了更好地解译SAR图像中的涡旋特征，该文提出了一种涡旋SAR图像仿真方法。首先，基于流体力学中典型的Burgers-Rott涡旋模型，建立涡旋2维表面流场；然后，利用SAR海洋成像仿真模型，仿真给定涡旋2维流场、海面风场以及雷达系统参数下的涡旋SAR图像。该文针对气旋式涡旋与反气旋式涡旋进行了仿真实验，并建立了仿真涡旋SAR图像的相似度评价标准。实验结果表明，仿真的涡旋SAR图像与真实星载涡旋SAR图像能够较好地吻合，验证了方法的有效性。
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关键词:
- 海洋涡旋 /
- SAR图像 /
- Burgers-Rott涡旋模型 /
- 图像仿真
Abstract: Oceanic eddies, which play an important role in ocean thermal cycling, is a significant branch of oceanic scientific research. Synthetic Aperture Radar (SAR) provides a large number of images for the observation and investigation of oceanic eddies. However, SAR imagery of oceanic eddies is affected by various environmental factors; as such, it is difficult to interpret eddy features from SAR images. Alternatively, simulated SAR images can be used to investigate eddy features; however, few methods have been established for simulating SAR images for oceanic eddies. To better interpret the eddy features in real SAR images, an SAR image simulation method for oceanic eddies is proposed in this paper. First, a two-dimensional eddy surface current field was built based on the Burgers-Rott vortex model in hydrodynamics; SAR eddy images were then simulated according to the given eddy current field, wind field, and radar parameters. Images of cyclonic and anticyclonic eddies were simulated and evaluated. In addition, a standard for evaluating the similarity between real and simulated SAR eddy images was established. The features of the simulated SAR eddy images show good similarity with the real SAR eddy images, which validates the effectiveness of the proposed simulation method. -
图 3 中国东海海域获取的ERS-2 SAR图像，获取时间为2009.08.19, 02:23:50 UTC
Figure 3. ERS-2 SAR image of the East China Sea obtained on August 19, 2009 at 02:23:50 UTC
图 5 相同参数下仿真SAR图像与ERS-2 SAR图像对比图
Figure 5. Comparison of simulated SAR image and ERS-2 SAR image under the same parameters
图 6 仿真SAR图像与ERS-2 SAR图像涡旋信息提取
Figure 6. Eddy information extraction of simulated SAR image and ERS-2 SAR image
图 7 吕宋海峡获取的ENVISAT-1 ASAR图像，获取时间为2010.06.11, 01:51:48 UTC
Figure 7. ENVISAT-1 ASAR image of the Luson Strait obtained on June 11, 2010 at 01:51:48 UTC
图 9 相同参数下仿真SAR图像与ENVISAT-1 ASAR图像对比图
Figure 9. Comparison of simulated SAR image and ENVISAT-1 ASAR image under the same parameters
图 10 仿真SAR图像与ENVISAT-1 ASAR图像涡旋信息提取
Figure 10. Eddy information extraction of simulated SAR image and ENVISAT-1 ASAR image
表 1 ERS-2 SAR参数
Table 1. SAR parameters of ERS-2
参数 数值 极化方式 VV 波段 C 入射角 23.0° 平台高度 780 km 平台速度 7500 m/s 
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表 2 涡旋信息提取结果
Table 2. Results of eddy information extraction
SAR图像 涡旋中心位置 涡旋直径 涡旋边缘长度 仿真SAR图像 (116,75) 18.9 km 35.7 km 真实SAR图像 (113,71) 18.7 km 35.4 km 绝对/相对误差 (3,4)/— 0.2 km/0.011 0.3 km/0.008
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表 3 ENVISAT-1 ASAR参数
Table 3. ASAR parameters of ENVISAT-1
参数 数值 极化方式 HH 波段 C 入射角 26.7° 平台高度 800 km 平台速度 7455 m/s
下载: 导出CSV
表 4 涡旋信息提取结果
Table 4. Results of eddy information extraction
SAR图像 涡旋中心位置 涡旋直径 涡旋边缘尺寸 仿真SAR图像 (144,78) 24.0 km 49.4 km 真实SAR图像 (147,81) 23.9 km 49.7 km 绝对/相对误差 (3,3)/— 0.1 km/0.004 0.3 km/0.006
下载: 导出CSV
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