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Coastal wind field retrieval from polarimetric synthetic aperture radar

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Acta Oceanologica Sinica 2014年第5期33卷 54-61页

作者： ZHANG Yi JIANG Xingwei SONG Qingtao LIN Mingsen xie xuetong National Satellite Ocean Application Service State Oceanic Administration Key Laboratory of Space Ocean Remote Sensing and Applications State Oceanic Administration

Coastal winds are strongly influenced by topology and discontinuity between land and sea surfaces. Wind assessment from remote sensing in such a complex area remains a challenge. Space-borne scatterometer does not provide any information about the coastal wind field, as the coarse spatial resolution hampers the radar backscattering. Synthetic aperture radar （SAR） with a high spatial resolution and all-weather observation abilities has become one of the most important tools for ocean wind retrieval, especially in the coastal area. Conventional methods of wind field retrieval from SAR, however, require wind direction as initial information, such as the wind direction from numerical weather prediction models （NWP）, which may not match the time of SAR image acquiring. Fortunately, the polarimetric observations of SAR enable independent wind retrieval from SAR images alone. In order to accurately measure coastal wind fields, this paper proposes a new method of using co-polarization backscattering coefficients from polarimetric SAR observations up to polarimetric correlation backscattering coefficients, which are acquired from the conjugate product of co-polarization backscatter and cross-polarization backscatter. Co-polarization backscattering coefficients and polarimetric correlation backscattering coefficients are obtained form Radarsat-2 single-look complex （SLC） *** maximum likelihood estimation is used to gain the initial results followed by the coarse spatial filtering and fine spatial filtering. Wind direction accuracy of the final inversion results is 10.67 with a wind speed accuracy of 0.32 m/s. Unlike previous methods, the methods described in this article utilize the SAR data itself to obtain the wind vectors and do not need external wind directional information. High spatial resolution and high accuracy are the most important features of the method described herein since the use of full polarimetric observations contains more information about the space

关键词： polarimetric synthetic aperture radar coastalwind field polarimetric correlation backscattering coefficients

The HY-2 satellite and its preliminary assessment

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International Journal of Digital Earth 2012年第3期5卷 266-281页

作者： Xingwei Jiang Mingsen Lin Jianqiang Liu Youguang Zhang xuetong xie Hailong Peng Wu Zhou National Satellite Ocean Application Service SOAChina

The HY-2 satellite was successfully launched on 16 August *** carried four microwave instruments into space for operationally observing dynamic ocean environment parameters on a global *** HY-2 satellite altimeter provides sea surface height(SSH),significant wave height(SWH),sea surface wind(SSW)speed,and polar ice sheet elevation,while the HY-2 satellite scatterometer provides SSW *** the same time,other oceanic and atmospheric parameters such as sea surface temperature(SST)and wind speed,water vapor and liquid water content can also be obtained by its onboard scanning microwave radio*** this paper,we show the data processing methods of the HY-2 satellite’s *** preliminary results show that wind vector,SSH,SWH,and SST conform to the designed technical specifications.

关键词： HY-2 satellite radar altimeter microwave scatterometer scanning microwave radiometer algorithm processing

Satellite SAR observation of the sea surface wind field caused by rain cells

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Acta Oceanologica Sinica 2016年第9期35卷 80-85页

作者： YE Xiaomin LIN Mingsen YUAN Xinzhe DING Jing xie xuetong ZHANG Yi XU Ying College of Information Science and Engineering Ocean University of China National Satellite Ocean Application Service State Oceanic Administration Key Laboratory of Space Ocean Remote Sensing and Application State Oceanic Administration School of Geographical Sciences Guangzhou University

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 *** footprints of rain cells on SAR images are caused by the scattering and attenuation of the rain drops,as well as the downward *** 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 *** 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 Met Op-A satellite and microwave scatterometer onboard Chinese HY-2 satellite,*** 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,*** 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 *** 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 *** 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 *** cases interpreted and analyzed in this study all show the same conclusion.

关键词： rain cells Synthetic Aperture Radar (SAR) sea surface wind field downdraft

Sea Winds散射计海面风场模糊去除方法研究

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北京大学学报（自然科学版） 2005年第6期41卷 882-889页

作者：解学通方裕陈克海陈晓翔北京大学地球与空间科学学院北京100871 中山大学遥感与地理信息工程系广州510275

利用最大似然法(MLE)对SeaWinds散射计数据反演得出的风矢量,一般存在2～4个模糊解,故需采用圆中数滤波法进行模糊去除.根据SeaWinds散射计第一模糊解的空间分布特性,归纳出一套适合SeaWinds散射计的模糊去除方法,并在理论上探讨了其适... 详细信息

利用最大似然法(MLE)对SeaWinds散射计数据反演得出的风矢量,一般存在2～4个模糊解,故需采用圆中数滤波法进行模糊去除.根据SeaWinds散射计第一模糊解的空间分布特性,归纳出一套适合SeaWinds散射计的模糊去除方法,并在理论上探讨了其适应性.该方法的圆中数定义简单,计算量小,且易于收敛.利用美国NASA提供的部分L2A原始数据对该方法进行验证的结果表明,对于简单风场分布情况,该方法在没有其他参考数据进行初始化的条件下,能有效解决SeaWinds轨道边缘区域的块状模糊问题.

关键词： SeaWinds 风场反演圆中数滤波块状模糊

一种新的SeaWinds散射计海面风场反演方法

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高技术通讯 2005年第10期15卷 98-104页

作者：解学通方裕陈晓翔陈克海北京大学遥感与地理信息系统研究所北京100871中山大学遥感与地理信息工程系广州510275 北京大学遥感与地理信息系统研究所北京100871 中山大学遥感与地理信息工程系广州510275

针对传统的最大似然法存在的主要缺点,在分析SeaWinds散射计模型函数表的基础上,根据雷达后向散射截面积(σ0)随风速和相对方位角的变化规律,提出了一种新的海面风场反演方法.然后利用SeaWinds散射计部分L2A实测数据对该方法进行了验证... 详细信息

针对传统的最大似然法存在的主要缺点,在分析SeaWinds散射计模型函数表的基础上,根据雷达后向散射截面积(σ0)随风速和相对方位角的变化规律,提出了一种新的海面风场反演方法.然后利用SeaWinds散射计部分L2A实测数据对该方法进行了验证,并在等风向间隔的条件下将该方法与传统的最大似然方法对同一实验数据的运行时间进行了比较.实验结果表明,与传统方法相比,该方法运行效率有明显提高,且反演结果与美国L2B反演结果十分接近.

关键词： SeaWinds散射计风场反演模型函数表查找表反演方法海面风场散射计最大似然法传统方法实验数据

人工神经网络在星载散射计海面风场反演建模中的应用

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北京大学学报（自然科学版） 2007年第4期43卷 460-467页

作者：陈克海解学通黄舟方裕陈晓翔中山大学遥感与地理信息工程系广州510275 北京大学遥感与地理信息系统研究所北京100871

地球物理模型函数(GMF)是散射计风场反演的基础及算法有效运行的前提条件。采用传统的统计方法建立GMF往往需要大量的、多种参数条件下的雷达后向散射测量数据。以圆锥扫描散射计SeaWinds为例,根据其特点,建立了一个两种极化方式下统一... 详细信息

地球物理模型函数(GMF)是散射计风场反演的基础及算法有效运行的前提条件。采用传统的统计方法建立GMF往往需要大量的、多种参数条件下的雷达后向散射测量数据。以圆锥扫描散射计SeaWinds为例,根据其特点,建立了一个两种极化方式下统一的神经网络模型函数(NNGMF),并对风速、相对风向采样间隔和测量值数目对模型精度的影响进行了详细分析。通过与Qscat-1模型进行比较,发现该神经网络模型在采样间隔较大或测量值数目较少的情况下,仍能较好地体现SeaWinds散射计的海面后向散射特性。

关键词：散射计海面风场地球物理模型函数(GMF) 神经网络

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基于频谱分析的SAR图像风场反演算法研究

测绘科学 2023年第11期48卷 153-161页

作者：陈克海张金兰解学通广东工贸职业技术学院测绘遥感信息学院广州510510 广州大学地理科学与遥感学院广州510006

针对SAR图像上的黑白相间的周期间条带蕴含有丰富的海面风场信息,基于频谱分析法提出了一种SAR风场反演算法。在SAR图像功率谱中自适应寻找风条纹具体波数范围,从该波数范围内的方向谱中提取海面3个风向模糊解,并使用圆中数滤波去除风... 详细信息

针对SAR图像上的黑白相间的周期间条带蕴含有丰富的海面风场信息,基于频谱分析法提出了一种SAR风场反演算法。在SAR图像功率谱中自适应寻找风条纹具体波数范围,从该波数范围内的方向谱中提取海面3个风向模糊解,并使用圆中数滤波去除风向模糊,得到风向唯一解。风向值确定后,利用地球物理模型求解出风速值。为了测试算法,对GF-3卫星SAR图像进行风场反演实验。实验表明,反演得到的SAR风场与ECMWF数值风场对比,风速绝对偏差均值和均方根误差分别为1.02m/s和1.32m/s,风向绝对偏差均值和均方根误差分别为12.22°和15.60°。算法能有效地从GF-3卫星SAR图像中反演出较高精度的风场,研究结果可为GF-3卫星SAR风场反演技术提供参考。

关键词：高分三号卫星合成孔径雷达风条纹风场反演频谱分析

Identification and removal of block ambiguities in sea surface wind field with scatterometers

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Science China Earth Sciences 2009年第2期52卷 242-249页

作者： CHEN KeHai1,2, xie xuetong3 & FANG Yu4 1 South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China 2 Graduate University of Chinese Academy of Sciences, Beijing 100049, China 3 School of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China 4 The Institute of Remote Sensing and GIS, Peking University, Beijing 100871, China South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou China Graduate University of Chinese Academy of Sciences Beijing China School of Electronic Science and Engineering National University of Defense Technology Changsha China The Institute of Remote Sensing and GIS Peking University Beijing China

The solution of the current wind retrieval algorithm for scatterometers has several wind vector ambi-guities, due to the bi-harmonic relationship between normalized backscattering cross section and the relative wind direction and the existence of the measurement error. In order to remove the ambiguities for a unique wind field, a circular median filter approach (CMF) is usually adopted. But under the con-dition for clustering distribution of the false ambiguities in some local areas, the CMF fails and thus engenders block ambiguities, which degrade the precision of the retrieved wind field. For such a situation, a technique of identification and removal of the block ambiguities is presented to further optimize the retrieved wind field after CMF. It is demonstrated in experiment that this technique can identify and remove most of the block ambiguities.

关键词： scatterometer block ambiguity identification and removal

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HY-2A微波散射计风场反演算法

中国工程科学 2013年第7期15卷 68-74页

作者：林明森邹巨洪解学通张毅国家卫星海洋应用中心北京100081

本文针对我国首颗自主发射的海洋二号(HY-2A)卫星微波散射计,建立了业务化运行的风场反演算法,该算法将散射计海面风矢量反演分为粗搜索和精搜索两个步骤,有效地提高了运算效率。采用矢量圆中数滤波算法进行风向模糊解去除,并采用NCEP... 详细信息

本文针对我国首颗自主发射的海洋二号(HY-2A)卫星微波散射计,建立了业务化运行的风场反演算法,该算法将散射计海面风矢量反演分为粗搜索和精搜索两个步骤,有效地提高了运算效率。采用矢量圆中数滤波算法进行风向模糊解去除,并采用NCEP风场作为背景场对初始场进行选择,提高了模糊去除准确性。算法的反演结果经与NDBC对比和ASCAT风场星星对比验证,结果表明HY-2A卫星微波散射计可提供风速精度优于2 m/s或10%,风向精度优于±20°的海面风场观测产品,可满足海洋科学研究和海洋业务应用的需求。

关键词： HY-2A 微波散射计风场反演算法