| 摘要: |
| ENVISAT ASAR(Advanced Synthetic Aperture Radar)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,因此其数据精度对模式预报结果有重要影响。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,按照能量分布可分为四种类型。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。本文对今后海浪反演算法的研究以及数据同化等问题具有参考价值。 |
| 关键词: ENVISAT ASAR波模式 海浪谱 海浪参数 精度验证 |
| DOI： |
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| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Validation of precision of retrieval algorithm and its retrieved data of ENVISAT ASAR wave mode data |
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Yu Haitao1, Wei Yongliang1, Tang Zeyan2, Liu Xiaoya1
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1.Shanghai Ocean University;2.Prediction Center of East China Sea,State Oceanic Administration
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| Abstract: |
| ENVISAT ASAR(Advanced Synthetic Aperture Radar)level 2 products provide the wave information about significant wave height (SWH), wave direction, wave length and 2D spectrum, which play an important role in wave models, so the precision of ASAR data are essential to model predictions. The precision of 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 SAR on the sea surface, there will be different results under various sea state. Compared with US NDBC buoy data, results showed that ASAR SWH data were overestimated under low sea state and underestimated under high sea state, and had better coincidence under medium sea state. The wave spectra retrieved from ASAR wave mode images can be categorized into four types after carefully analyzing the energy distribution and spectral shapes. The accuracy of wave parameters of different spectra types was discussed by studying the corresponding two dimensional spectra, results showed that in cases of normal spectra with single direction, the SWH and wave direction were consistent with buoy data, while in cases of spectra with 180° wave direction ambiguity only SWH showed good consistence, and spectra with disordered shapes showed poor results. This study will supply valuable reference for the future research of wave retrieval algorithm or data assimilation. |
| Key words: ENVISAT ASAR wave mode wave spectrum wave parameters precision validation |