高分三號衛(wèi)星對海浪的首次定量遙感
發(fā)布時間：2019-02-28 14:50
【摘要】：高分三號(GF-3)是我國首顆C頻段多極化高分辨率微波遙感衛(wèi)星,于2016年8月10日在太原衛(wèi)星發(fā)射中心成功發(fā)射。GF-3 SAR衛(wèi)星入射角范圍約為20°—50°,具備單極化、雙極化和全極化等多極化工作能力,還是世界上成像模式最多的SAR衛(wèi)星,具有12種成像模式。不僅涵蓋了傳統(tǒng)的條帶、掃描成像模式,而且可在聚束、條帶、掃描、波浪、全球觀測、高低入射角等多種成像模式下實現(xiàn)自由切換,既可以探地,又可以觀海,達(dá)到"一星多用"的效果。近日,國家海洋局第二海洋研究所衛(wèi)星海洋環(huán)境動力學(xué)國家重點實驗室利用首批GF-3合成孔徑雷達(dá)(SAR)遙感數(shù)據(jù)(圖1)對夏威夷西北部附近太平洋海域的海浪進(jìn)行了首次定量分析和反演研究(圖2)。圖1為GF-3 SAR的灰度圖像,成像時間為2016年9月2日8:30(GMT),衛(wèi)星此時飛行速度約為7.6km,極化方式為VV極化,飛行方向為降軌,空間分辨率為8m×8m,中心入射角為28.32°。由圖1可以看出,SAR圖像上存在明顯的黑白相間的海浪條紋,說明海浪在圖像上能夠順利成像。通過提取灰度圖像上的調(diào)制信息,并作傅里葉變換分析,可得到包含海浪信息的圖像譜。進(jìn)一步,基于經(jīng)典的Hasselmann SAR海浪成像模型的準(zhǔn)線性形式,同時估計傾斜調(diào)制、水動力調(diào)制和聚束調(diào)制等三種海浪調(diào)制函數(shù)(MTF),可以利用圖像譜反演得到海浪譜,此時的海浪譜主要為較長波長的涌浪信息,至于較短波長的海浪信息提取,由于受到方位向截斷效應(yīng)的影響,則需要引入初猜譜加以補償實現(xiàn)。圖2為圖1反演的海面涌浪參數(shù)。從圖2可以看出,該海域海浪由西北向東南傳播(即由外海向近岸傳播),平均波長約200m,有效波高從2.5m到4.0m不等,能夠反映浪場的分布差異。由于沒有同步的現(xiàn)場觀測資料和其他衛(wèi)星遙感資料,本文將這些結(jié)果與歐洲中期天氣預(yù)報中心(ECMWF)提供的ERA-Interim再分析數(shù)據(jù)進(jìn)行了比對。初步反演與比對結(jié)果表明,兩者有較好的一致性,但本文的反演結(jié)果反映了更多的細(xì)節(jié),顯示GF-3 SAR有能力對海面涌浪信息進(jìn)行高分辨率的觀測;同時,再次表明ERA-Interim再分析數(shù)據(jù)低估了有效波高,因此GF-3衛(wèi)星的發(fā)射將有利于提高全球海浪的遙感觀測水平。
[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 擄to 50 擄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 擄. 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.
【作者單位】： 國家海洋局第二海洋研究所衛(wèi)星海洋環(huán)境動力學(xué)國家重點實驗室;
【基金】：國家重點研發(fā)計劃,2016YFC1401007號 國家自然科學(xué)基金項目,41306191號,41306192號,41621064號 國家高分辨率對地觀測系統(tǒng)重大專項,41-Y20A14-9001-15/16號
【分類號】：P715.7
本文編號：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 擄to 50 擄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 擄. 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.
【作者單位】： 國家海洋局第二海洋研究所衛(wèi)星海洋環(huán)境動力學(xué)國家重點實驗室;
【基金】：國家重點研發(fā)計劃,2016YFC1401007號 國家自然科學(xué)基金項目,41306191號,41306192號,41621064號 國家高分辨率對地觀測系統(tǒng)重大專項,41-Y20A14-9001-15/16號
【分類號】：P715.7
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