海面粗糙度(Sea surface roughness, SSR)是用來描述海面狀態的重要基礎物理參數之一。太陽耀光是由太陽光直接從海面反射並被遙感器接收的部分,其強度受到海面粗糙度的強烈影響。本文研究提出了一種基於多角度太陽耀光遙感影像的像素尺度的海面粗糙度估算新模型。為了驗證我們的模型,利用Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)獲得的高解析度多角度太陽耀光遙感影像估算獲得了高解析度海面粗糙度。然後轉換成風速,利用再分析風場數據和浮標風速數據進行了誤差評估,結果表明,三者吻合較好,具有與其他遙感方法相當的風速探測精度。可見,估算獲得的海面粗糙度是具有相當可信的。文章還給出了海面溢油、海底地形和內波等三個典型海洋現象的高解析度海面粗糙度遙感估算結果,其顯示了詳細的海洋學特徵,且具有低噪聲和像素尺度粗糙度的定量變化特徵。研究結果表明,利用多角度太陽耀光遙感影像進行高解析度海洋動力現象觀測和分析是可行的,為海面粗糙度和海洋動力過程遙感觀測提供了新的思路。
部分海面粗糙度估算結果圖
Estimation results for the sea surface roughness derived by using six multi-angle ASTER images matched to field buoy wind speeds. The red stars denote the locations of the field buoys.
淺海水下地形海面粗糙度估算實例
(a) Sub-image of the estimated SSR image showing submarine sand waves acquired on 16 July 2003 in the Taiwan Strait. The black line labeled 「Profile」 is the SSR profile across five sand waves from north to south plotted in (b). (b) SSR profile across five sand waves along the 「Profile」 line in (a) from north to south. The five red circles represent the location of sand-wave ridges.
論文應用:Zhang, H., K. Yang, X. Lou, Y. Li, G. Zheng, J. Wang, X. Wang, L. Ren, D. Li and A. Shi. Observation of sea surface roughness at a pixel scale using multi-angle sun glitter images acquired by the ASTER sensor. Remote Sensing of Environment, 2018, 208: 97-108.