| 摘要: |
| 搭载在欧洲环境卫星(ENVISAT)上的高级合成孔径雷达(Advanced Synthetic Aperture Radar,ASAR)二级波模式数据提供了诸多海浪信息包括有效波高、波向、波长和二维海浪谱等,在海浪预报模式中具有重要作用。本文拟利用浮标观测数据对ASAR波模式算法及其反演数据精度进行对比验证。由于SAR卫星在海面的特殊成像机制,不同海况下会有不同的测量结果,通过与美国国家浮标中心(NDBC)的浮标数据对比,显示ASAR有效波高在高海况下低估和在低海况下高估的现象,在中等海况下的测量结果较优。通过研究ASAR数据集中对应的海浪谱,按照能量与方向分布可分为四种类型:单一方向海浪谱(Ⅰ类谱),180°方向模糊海浪谱(Ⅱ类谱),海浪两个方向且能量分布杂乱(Ⅲ类谱),多个传播方向且谱型杂乱海浪谱(Ⅳ类谱)。探究在不同类型下的海浪参数的精度,结果表明在单一波向正常海浪谱情况下,有效波高、波向与浮标数据一致性较好,存在180°方向模糊的对称海浪谱仅有效波高精度较高,谱型杂乱的海浪谱海浪有效波高和波向反演结果均较差。 |
| 关键词: 星载高级合成孔径雷达波模式 海浪谱 海浪参数 精度验证 |
| DOI：10.11759/hykx20210712001 |
| 分类号:P731.22 |
| 基金项目:国家自然科学基金项目(41976174,41606196) |
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| Validation of the precision of retrieval algorithm and its retrieved data of Space-borne Advance Synthetic Aperture Radar wave mode data |
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YU Hai-tao1, TANG Ze-yan2, WEI Yong-liang1,3,4, LIU Xiao-ya1
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1.College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China;2.Prediction Center of East China Sea, State Oceanic Administration, Shanghai 200081, China;3.Engineering Research Center on Estuarine and Oceanographic Mapping, Shanghai Municipal Ocean Bureau, Shanghai 201306, China;4.International Center for Marine Studies, Shanghai Ocean University, Shanghai 201306, China
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| Abstract: |
| ENVISAT Advanced Synthetic Aperture Radar (ASAR) level 2 products provide wave information about significant wave height (SWH), wave direction, wavelength, and 2D spectrum, all playing an important role in wave models; hence, the precision of ASAR data is essential for the model predictions. The precision of the retrieval algorithm and its retrieved data of ENVISAT ASAR wave mode data will be validated using buoy observations. Due to the special imaging mechanism of Synthetic Aperture Radar on the sea surface, there will be different results under various sea states. When compared with buoy data from the American National Data Buoy Center , the results revealed that ASAR SWH data were overestimated under low sea states and underestimated under high sea states with better coincidence under medium sea states. After analyzing the energy distribution and spectral shapes, the wave spectra retrieved from ASAR wave mode images can be categorized into four types, i.e., wave spectra with a single direction (type I), spectra with 180° wave direction ambiguity (type II), spectra with two wave directions but different spectral energy (type III) and wave spectra with disordered shapes (type IV). The accuracy of the wave parameters of different spectral types was discussed by studying the corresponding two-dimensional spectra. The results showed that the SWH and wave direction was consistent with the buoy data for the normal spectra with a single direction; however, only SWH showed good consistency for the spectra with 180° wave direction ambiguity. The spectra with disordered shapes showed poor results. This study will be a valuable reference for future research on wave retrieval algorithms and data assimilation. |
| Key words: ENVISAT ASAR wave mode wave spectrum wave parameters precision validation |
