| 星载SAR对雨团催生海面风场的观测研究 |
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| 引用本文： | 叶小敏,林明森,袁新哲,丁静,解学通,张毅,徐莹.星载SAR对雨团催生海面风场的观测研究[J].海洋学报(英文版),2016,35(9):80-85. |
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| 作者姓名： | 叶小敏 林明森 袁新哲 丁静 解学通 张毅 徐莹 |
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| 作者单位： | 中国海洋大学 信息科学与工程学院, 青岛, 266100;国家海洋局 国家卫星海洋应用中心, 北京, 100081;国家海洋局 空间海洋遥感与应用研究重点实验室, 北京, 100081,国家海洋局 国家卫星海洋应用中心, 北京, 100081;国家海洋局 空间海洋遥感与应用研究重点实验室, 北京, 100081,国家海洋局 国家卫星海洋应用中心, 北京, 100081;国家海洋局 空间海洋遥感与应用研究重点实验室, 北京, 100081,国家海洋局 国家卫星海洋应用中心, 北京, 100081;国家海洋局 空间海洋遥感与应用研究重点实验室, 北京, 100081,广州大学 地理科学学院, 广州, 510006,国家海洋局 国家卫星海洋应用中心, 北京, 100081;国家海洋局 空间海洋遥感与应用研究重点实验室, 北京, 100081,中国海洋大学 信息科学与工程学院, 青岛, 266100;国家海洋局 国家卫星海洋应用中心, 北京, 100081;国家海洋局 空间海洋遥感与应用研究重点实验室, 北京, 100081 |
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| 摘 要： | 雨团或对流雨是热带与亚热带地区的主要降雨形式，较易被高分辨率星载合成孔径雷达（SAR）探测到。SAR图像上的雨团足印是由大气中雨滴的散射与吸收、下沉气流等共同导致形成的。本文以RADARSAT-2卫星100 m分辨率的SAR图像上雨团引起的海面风场及其结构反演与解译作为实例进行分析。使用CMOD4地球物理模式函数，分别以NCEP再分析数据、欧洲MetOp-A卫星先进散射计（ASCAT）和中国HY-2卫星微波散射计的风向为外部风向，进行了SAR图像的海面风场反演。反演的海面风速相对于NCEP、ASCAT和HY-2的均方根误差（RMSE）分别为1.48 m/s,1.64 m/s和2.14 m/s。SAR图像上一侧明亮另一侧昏暗的圆形信号图斑被解译为雨团携带的下沉气流对海面风场（海面粗糙度）的改变所致。平行于海面背景风场其通过雨团圆形足印中心的剖面上的风速变化可拟合为正弦或余弦曲线，其拟合线性相关系数均不低于0.80。背景风场的风速大小、雨团引起的风速大小以及雨团足印的直径可利用拟合曲线获得，雨团足印的直径大小一般为数千米或数十千米，本文的8例个例解译与分析均验证了该结论。
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| 关 键 词： | 雨团 合成孔径雷达 海面风场 下沉气流 |
| 收稿时间： | 2015/9/14 0:00:00 |
| 修稿时间： | 2015/11/9 0:00:00 |
Satellite SAR observation of the sea surface wind field caused by rain cells |
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| YE Xiaomin,LIN Mingsen,YUAN Xinzhe,DING Jing,XIE Xuetong,ZHANG Yi and XU Ying.Satellite SAR observation of the sea surface wind field caused by rain cells[J].Acta Oceanologica Sinica,2016,35(9):80-85. |
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| Authors: | YE Xiaomin LIN Mingsen YUAN Xinzhe DING Jing XIE Xuetong ZHANG Yi and XU Ying |
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| Institution: | College of Information Science and Engineering, Ocean University of China, Qingdao 266100, China;National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China;Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China,National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China;Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China,National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China;Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China,National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China;Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China,School of Geographical Sciences, Guangzhou University, Guangzhou 510006, China,National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China;Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China and College of Information Science and Engineering, Ocean University of China, Qingdao 266100, China;National Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China;Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081, China |
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| Abstract: | Rain cells or convective rain, the dominant form of rain in the tropics and subtropics, can be easy detected by satellite Synthetic Aperture Radar (SAR) images with high horizontal resolution. The footprints of rain cells on SAR images are caused by the scattering and attenuation of the rain drops, as well as the downward airflow. In this study, we extract sea surface wind field and its structure caused by rain cells by using a RADARSAT-2 SAR image with a spatial resolution of 100 m for case study. We extract the sea surface wind speeds from SAR image by using CMOD4 geophysical model function with outside wind directions of NCEP final operational global analysis data, Advance Scatterometer (ASCAT) onboard European MetOp-A satellite and microwave scatterometer onboard Chinese HY-2 satellite, respectively. The root-mean-square errors (RMSE) of these SAR wind speeds, validated against NCEP, ASCAT and HY-2, are 1.48 m/s, 1.64 m/s and 2.14 m/s, respectively. Circular signature patterns with brighter on one side and darker on the opposite side on SAR image are interpreted as the sea surface wind speed (or sea surface roughness) variety caused by downdraft associated with rain cells. The wind speeds taken from the transect profile which superposes to the wind ambient vectors and goes through the center of the circular footprint of rain cell can be fitted as a cosine or sine curve in high linear correlation with the values of no less than 0.80. The background wind speed, the wind speed caused by rain cell and the diameter of footprint of the rain cell with kilometers or tens of kilometers can be acquired by fitting curve. Eight cases interpreted and analyzed in this study all show the same conclusion. |
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| Keywords: | rain cells Synthetic Aperture Radar(SAR) sea surface wind field downdraft |
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