Estimation of wind stress using dual-frequency TOPEX data
Estimation of wind stress using dual-frequency TOPEX data
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DOI：
10.1029/98jc00193
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发表时间：
1998-10
影响因子：
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通讯作者：
T. Elfouhaily;D. Vandemark;J. Gourrion;B. Chapron
中科院分区：
文献类型：
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作者：
T. Elfouhaily;D. Vandemark;J. Gourrion;B. Chapron
TOPEX/POSEIDON卫星载有第一个双频雷达高度计。目前，MonteCarlo（Ku波段）算法用于从高度计的雷达截面测量值（σ 0 Ku）中反演表面风速。这些算法工作得相当好，但也知道高度计风估计可能受到残余效应的污染，例如嵌入在σ 0 Ku测量中的海况。调查风检索使用两个频率的潜在好处，它表明，一个简单的评估TOPEX数据产生以前无法获得的信息，特别是对于高和低风速。随着风速的增加，双频数据提供了一个测量更直接地联系到短尺度表面粗糙度，这反过来又与当地的表面风应力。使用全球TOPEX σ0°数据集和TOPEX的有效波高（Hs）估计作为海况发展程度的替代，还表明两个TOPEX σ0测量值之间的差异强烈地证明了非局部海况特征。复合散射理论被用来说明如何双频数据可以提供一个改进的摩擦速度模型，特别是对于大于7米/秒的风。风速转换包括使用与TOPEX Hs数据馈送的海况相关的阻力系数。两个TOPEX浮标数据集（来自国家数据浮标中心（NDBC）和海洋大气交换结构，海洋异质性：研究实验（信号量）活动）被用来测试新的风速算法。与Monsieur Witter和Chelton [1991]模型相比，风速估计得到了可测量的改进。
The TOPEX/POSEIDON satellite carries the first dual-frequency radar altimeter. Monofrequency (Ku-band) algorithms are presently used to retrieve surface wind speed from the altimeter's radar cross-section measurement (σ0Ku). These algorithms work reasonably well, but it is also known that altimeter wind estimates can be contaminated by residual effects, such as sea state, embedded in the σ0Ku measurement. Investigating the potential benefit of using two frequencies for wind retrieval, it is shown that a simple evaluation of TOPEX data yields previously unavailable information, particularly for high and low wind speeds. As the wind speed increases, the dual-frequency data provides a measurement more directly linked to the short-scale surface roughness, which in turn is associated with the local surface wind stress. Using a global TOPEX σ0° data set and TOPEX's significant wave height (Hs) estimate as a surrogate for the sea state's degree of development, it is also shown that differences between the two TOPEX σ0 measurements strongly evidence nonlocal sea state signature. A composite scattering theory is used to show how the dual-frequency data can provide an improved friction velocity model, especially for winds above 7 m/s. A wind speed conversion is included using a sea state dependent drag coefficient fed with TOPEX Hs data. Two colocated TOPEX-buoy data sets (from the National Data Buoy Center (NDBC) and the Structure des Echanges Mer-Atmosphre, Proprietes des Heterogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) campaign) are employed to test the new wind speed algorithm. A measurable improvement in wind speed estimation is obtained when compared to the monofrequency Witter and Chelton [1991] model.