| REN Lin,YANG Jingsong,ZHENG Gang,WANG Juan. 2015. Significant wave height estimation using azimuth cutoff of C-band RADARSAT-2 single-polarization SAR images. Acta Oceanologica Sinica, 34(12):93－101 |
| Significant wave height estimation using azimuth cutoff of C-band RADARSAT-2 single-polarization SAR images |
| 利用C波段RADARSAT-2单极化SAR图像的方位向截断波长估计有效波高 |
| Received:November 12, 2014 Revised:June 05, 2015 |
| DOI：10.1007/s13131-015-0769-6 |
| Key words:SAR single-polarization significant wave height azimuth cutoff |
| 中文关键词: SAR 单极化 有效波高 方位向截断波长 |
| 基金项目:The National Natural Science Youth Foundation of China under contract Nos 41306191 and 41306192; the National High Technology Research and Development Program of China (863 Program) of China under contract No. 2013AA09A505; the Scientific Research Fund of the Second Institute of Oceanography, State Oceanic Administration of China under contract No. JG1317. |
| Author Name | Affiliation | E-mail | | REN Lin | State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China | renlin210@sio.org.cn | | YANG Jingsong | State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China | | | ZHENG Gang | State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China | | | WANG Juan | State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China | |
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| Abstract: |
| This paper proposes two simple models, look-up table (LUT) model and empirical model, to directly retrieve significant wave height (Hs) using synthetic aperture radar (SAR) azimuth cutoff (λc). Both models aim at C-band VV, HH, VH, and HV single-polarization SAR images. The LUT model relates Hs to λc, while the empirical model relates Hs to both λc and SAR range-to-velocity (β). The LUT model coefficients are derived by simulation under different sea states and observation conditions, which depend on incidence angle (θ), wave direction (dw), and β but are independent of polarization. The empirical model coefficients are obtained by fitting the collocated data, which only depend on polarization. To fit empirical model coefficients and validate the two models, C-band RADARSAT-2 fine quad-polarization (VV+HH+VH+HV) single-look complex (SLC) SAR images and collocated buoy data are collected. Retrieved Hs, using Yang model and the two models proposed in this paper from four kinds of polarization SAR data, are compared with buoy Hs. Results show that both LUT and empirical models have the capacity of retrieving Hs from C-band RADARSAT-2 co-polarization SAR data, while Yang model is not suitable for these kinds of SAR data. Moreover, the empirical model is also valid for cross-polarization SAR data showing clear ocean wave stripes. |
| 中文摘要: |
| 本文提出两种简单的有效波高(Hs)反演模型,即查找表(LUT)模型和经验模型,它们直接利用合成孔径雷达(SAR)图像的方位向截断波长(λc)反演Hs,两种模型主要针对C波段VV,HH,VH和HV单极化SAR图像。LUT模型中Hs是λc的函数,模型系数通过不同海况和观测条件下的仿真方法获取,系数与入射角(θ),波向(dw)和距离速度比(β)相关,与极化无关。经验模型中Hs是λc和β的函数,模型系数通过拟合同步观测数据得到,系数仅与极化相关。为拟合经验模型系数和验证两种模型的有效性,我们收集了C波段RADARSAT-2高精度全极化(VV+HH+VH+HV)单视复图像(SLC) SAR数据,和同步的浮标数据,分别利用Yang模型和文中提出的两种模型,反演出四种极化SAR数据的Hs。通过反演的Hs和浮标Hs的比较表明,LUT模型和经验模型都能够利用同极化(VV和HH)SAR数据反演Hs,但Yang模型针对该类型数据反演效果不佳。同时,针对存在清晰海浪条纹的交叉极化(VH和HV)SAR数据,经验模型也具有反演其Hs的能力。 |
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