高分三号卫星对海浪的首次定量遥感
发布时间：2019-02-28 14:50
【摘要】：高分三号(GF-3)是我国首颗C频段多极化高分辨率微波遥感卫星,于2016年8月10日在太原卫星发射中心成功发射。GF-3 SAR卫星入射角范围约为20°—50°,具备单极化、双极化和全极化等多极化工作能力,还是世界上成像模式最多的SAR卫星,具有12种成像模式。不仅涵盖了传统的条带、扫描成像模式,而且可在聚束、条带、扫描、波浪、全球观测、高低入射角等多种成像模式下实现自由切换,既可以探地,又可以观海,达到"一星多用"的效果。近日,国家海洋局第二海洋研究所卫星海洋环境动力学国家重点实验室利用首批GF-3合成孔径雷达(SAR)遥感数据(图1)对夏威夷西北部附近太平洋海域的海浪进行了首次定量分析和反演研究(图2)。图1为GF-3 SAR的灰度图像,成像时间为2016年9月2日8:30(GMT),卫星此时飞行速度约为7.6km,极化方式为VV极化,飞行方向为降轨,空间分辨率为8m×8m,中心入射角为28.32°。由图1可以看出,SAR图像上存在明显的黑白相间的海浪条纹,说明海浪在图像上能够顺利成像。通过提取灰度图像上的调制信息,并作傅里叶变换分析,可得到包含海浪信息的图像谱。进一步,基于经典的Hasselmann SAR海浪成像模型的准线性形式,同时估计倾斜调制、水动力调制和聚束调制等三种海浪调制函数(MTF),可以利用图像谱反演得到海浪谱,此时的海浪谱主要为较长波长的涌浪信息,至于较短波长的海浪信息提取,由于受到方位向截断效应的影响,则需要引入初猜谱加以补偿实现。图2为图1反演的海面涌浪参数。从图2可以看出,该海域海浪由西北向东南传播(即由外海向近岸传播),平均波长约200m,有效波高从2.5m到4.0m不等,能够反映浪场的分布差异。由于没有同步的现场观测资料和其他卫星遥感资料,本文将这些结果与欧洲中期天气预报中心(ECMWF)提供的ERA-Interim再分析数据进行了比对。初步反演与比对结果表明,两者有较好的一致性,但本文的反演结果反映了更多的细节,显示GF-3 SAR有能力对海面涌浪信息进行高分辨率的观测;同时,再次表明ERA-Interim再分析数据低估了有效波高,因此GF-3卫星的发射将有利于提高全球海浪的遥感观测水平。
[Abstract]:GF-3, the first C-band multi-polarization high-resolution microwave remote sensing satellite in China, was successfully launched at Taiyuan Satellite launch Center on August 10, 2016. GF-3 SAR satellite has an incidence angle ranging from 20 掳to 50 掳and has single polarization. The dual-polarization and full-polarization multi-polarization SAR satellites also have the most imaging modes in the world, with 12 imaging modes. It not only covers the traditional strip, scanning imaging mode, but also can realize free switching in various imaging modes, such as bunching, strip, scanning, wave, global observation, high and low incident angles, etc., which can not only explore the ground but also view the sea. Achieve the effect of "multi-use one star". Recently, The State key Laboratory for Satellite Marine Environmental Dynamics of the second Marine Institute of the State Oceanic Administration using the first batch of GF-3 synthetic Aperture Radar (SAR) remote sensing data (figure 1) for ocean waves in the Pacific Ocean near northwest Hawaii (figure 1) The first quantitative analysis and inversion study are carried out (Fig. 2). Figure 1 shows the grayscale image of GF-3 SAR. The imaging time is 8:30 on September 2, 2016, and the flying speed of the (GMT), satellite is about 7.6 km, the polarization mode is VV polarization, the direction of flight is de-orbiting, and the spatial resolution is 8m 脳 8m. The central incidence angle is 28.32 掳. From figure 1, it can be seen that there are obvious black and white wave stripes on the SAR image, indicating that the waves can be imaging smoothly on the image. By extracting modulation information from gray-scale image and analyzing it by Fourier transform, the image spectrum containing ocean wave information can be obtained. Furthermore, based on the quasilinear form of the classical Hasselmann SAR wave imaging model, three wave modulation functions, such as tilt modulation, hydrodynamic modulation and bunching modulation, are estimated at the same time, and the wave spectrum can be obtained by using image spectrum inversion. At this time, the wave spectrum is mainly the surging information of longer wavelength. As for the extraction of wave information of shorter wavelength, due to the effect of azimuth truncation, it is necessary to introduce the initial guess spectrum to compensate. Fig. 2 shows the sea-level surge parameters retrieved from fig. 1. It can be seen from fig. 2 that the sea waves propagate from northwest to southeast (that is, from the outer sea to the nearshore) with an average wavelength of about 200 m and an effective wave height ranging from 2.5 m to 4.0 m, which can reflect the distribution difference of the wave field. Since there is no synchronous in-situ observation data and other satellite remote sensing data, these results are compared with the ERA-Interim reanalysis data provided by the European Center for medium-range Weather Forecast (ECMWF). The results of preliminary inversion and comparison show that both of them are in good agreement, but the inversion results in this paper reflect more details, indicating that GF-3 SAR has the ability to make high-resolution observations of sea surface surges. At the same time, it is shown again that the ERA-Interim reanalysis data underestimates the effective wave height. Therefore, the launch of the GF-3 satellite will help to improve the level of remote sensing observation of the global ocean waves.
【作者单位】： 国家海洋局第二海洋研究所卫星海洋环境动力学国家重点实验室;
【基金】：国家重点研发计划,2016YFC1401007号 国家自然科学基金项目,41306191号,41306192号,41621064号 国家高分辨率对地观测系统重大专项,41-Y20A14-9001-15/16号
【分类号】：P715.7
本文编号：2431897
[Abstract]:GF-3, the first C-band multi-polarization high-resolution microwave remote sensing satellite in China, was successfully launched at Taiyuan Satellite launch Center on August 10, 2016. GF-3 SAR satellite has an incidence angle ranging from 20 掳to 50 掳and has single polarization. The dual-polarization and full-polarization multi-polarization SAR satellites also have the most imaging modes in the world, with 12 imaging modes. It not only covers the traditional strip, scanning imaging mode, but also can realize free switching in various imaging modes, such as bunching, strip, scanning, wave, global observation, high and low incident angles, etc., which can not only explore the ground but also view the sea. Achieve the effect of "multi-use one star". Recently, The State key Laboratory for Satellite Marine Environmental Dynamics of the second Marine Institute of the State Oceanic Administration using the first batch of GF-3 synthetic Aperture Radar (SAR) remote sensing data (figure 1) for ocean waves in the Pacific Ocean near northwest Hawaii (figure 1) The first quantitative analysis and inversion study are carried out (Fig. 2). Figure 1 shows the grayscale image of GF-3 SAR. The imaging time is 8:30 on September 2, 2016, and the flying speed of the (GMT), satellite is about 7.6 km, the polarization mode is VV polarization, the direction of flight is de-orbiting, and the spatial resolution is 8m 脳 8m. The central incidence angle is 28.32 掳. From figure 1, it can be seen that there are obvious black and white wave stripes on the SAR image, indicating that the waves can be imaging smoothly on the image. By extracting modulation information from gray-scale image and analyzing it by Fourier transform, the image spectrum containing ocean wave information can be obtained. Furthermore, based on the quasilinear form of the classical Hasselmann SAR wave imaging model, three wave modulation functions, such as tilt modulation, hydrodynamic modulation and bunching modulation, are estimated at the same time, and the wave spectrum can be obtained by using image spectrum inversion. At this time, the wave spectrum is mainly the surging information of longer wavelength. As for the extraction of wave information of shorter wavelength, due to the effect of azimuth truncation, it is necessary to introduce the initial guess spectrum to compensate. Fig. 2 shows the sea-level surge parameters retrieved from fig. 1. It can be seen from fig. 2 that the sea waves propagate from northwest to southeast (that is, from the outer sea to the nearshore) with an average wavelength of about 200 m and an effective wave height ranging from 2.5 m to 4.0 m, which can reflect the distribution difference of the wave field. Since there is no synchronous in-situ observation data and other satellite remote sensing data, these results are compared with the ERA-Interim reanalysis data provided by the European Center for medium-range Weather Forecast (ECMWF). The results of preliminary inversion and comparison show that both of them are in good agreement, but the inversion results in this paper reflect more details, indicating that GF-3 SAR has the ability to make high-resolution observations of sea surface surges. At the same time, it is shown again that the ERA-Interim reanalysis data underestimates the effective wave height. Therefore, the launch of the GF-3 satellite will help to improve the level of remote sensing observation of the global ocean waves.
【作者单位】： 国家海洋局第二海洋研究所卫星海洋环境动力学国家重点实验室;
【基金】：国家重点研发计划,2016YFC1401007号 国家自然科学基金项目,41306191号,41306192号,41621064号 国家高分辨率对地观测系统重大专项,41-Y20A14-9001-15/16号
【分类号】：P715.7
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