THE EFFECT OF THE DEGREE OF WAVE DEVELOPMENT ON THE SEA STATE BIAS IN RADAR ALTIMETRY MEASUREMENT
THE EFFECT OF THE DEGREE OF WAVE DEVELOPMENT ON THE SEA STATE BIAS IN RADAR ALTIMETRY MEASUREMENT
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DOI：
10.1029/90jc02319
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发表时间：
1991-01
影响因子：
--
通讯作者：
L. Fu;R. Glazman
中科院分区：
文献类型：
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作者：
L. Fu;R. Glazman
评估了波浪发展程度对地球卫星高度计高度测量中海况偏差（SSB）的影响。理论考虑表明，测高 SSB 通常不是有效波高的线性函数，而是还取决于波浪发展的其他因素。特别令人感兴趣的是它对波龄的依赖性，波龄定义为主要海浪的相速度与海洋风速的比率。我们根据高度计测量的有效波高 (H⅓) 和风速来相当粗略地估计波龄。在一般情况下，当海水与风不平衡时，该估计值可能不符合严格意义上的波龄，因此本文将其称为“伪波龄”。然而，赝波年龄是波浪发展程度的粗略指标。通过分析 2.7 年的地球卫星数据发现，SSB 对伪波年龄依赖性的总体趋势与理论预测非常吻合：对于给定的 H⅓，SSB 随着波浪发展程度（通过伪波年龄测量）的增加而减小。这一经验趋势的模型为 SSB= A(xi/xim)M H⅓，其中 xi 和 xim 分别为伪波年龄及其平均值； A = 0.013 ± 0.005，M = −0.88 ± 0.37。从统计上看，该模型的性能略优于标准模型（即 SSB = β H⅓，其中 β 为常数）。就全局均方根误差而言，改进了 1.6 厘米。然而，由于波浪发展的程度随季节和地理位置的不同而变化，当厘米级、盆地尺度的信号成为研究的重点时，这种微小的改进对于未来更准确的测高任务可能变得很重要。
The effect of the degree of wave development on the sea state bias (SSB) in Geosat altimeter height measurement is evaluated. Theoretical considerations suggest that the altimetric SSB is generally not a linear function of significant wave height but depends also on other factors of wave development. Of particular interest is its dependence on wave age, defined as the ratio of the phase speed of the dominant ocean waves to ocean wind speed. We estimate wave age rather crudely, on the basis of the significant wave height (H⅓) and wind speed measured by the altimeter. Under general conditions when the sea is not in equilibrium with the wind, this estimate may not correspond to the wave age in a strict sense and hence is called “pseudo wave age” in this paper. Nevertheless, the pseudo wave age is a rough indicator for the degree of wave development. The general trend in the dependence of the SSB on pseudo wave age, as found by analyzing 2.7 years' worth of Geosat data, agrees well with the theoretical prediction: for a given H⅓, the SSB decreases as the degree of the wave development (measured by the pseudo wave age) increases. This empirical trend is modeled as SSB= A(ξ/ξm)M H⅓, where ξ and ξm are the pseudo wave age and its average value, respectively; A = 0.013 ± 0.005, and M = −0.88 ± 0.37. Statistically, this model performs slightly better than a standard model (i.e., SSB = β H⅓ with β being a constant). In terms of the global rms error the improvement is by 1.6 cm. However, because the degree of wave development varies with the season and geographical location, this small improvement could become important for more accurate altimetric missions in the future when the centimetric, basin-scale signals are the focus of the study.