On the improvements to the wave statistics of narrowbanded waves when applied to broadbanded waves
On the improvements to the wave statistics of narrowbanded waves when applied to broadbanded waves
复制标题
DOI：
10.1029/2005jc003106
复制
发表时间：
2006-11
影响因子：
--
通讯作者：
Guizhen Zheng;P. Cong;Yuhua Pei
中科院分区：
文献类型：
--
作者：
Guizhen Zheng;P. Cong;Yuhua Pei
[1] 在窄带近似的基础上，推导了局部波高和海洋表面波周期的联合概率分布函数和边际概率分布函数（pdf），并将其近似视为波峰到波谷波高和零上渡周期的函数。为了将它们应用于宽带波，已经对这些概率密度函数提出了各种校正方案。本文致力于仔细研究这些校正方案。首先推导了局部波高和离散波高与周期分布之间的关系。这一推导为 Stansell 等人的改进提供了精确的解释。 （2004）和郑等人。 （2004）。由此产生的关系与 Kitano 和 Mase (1998) 所推导的关系不同，他们改进的波高分布依赖于后者。对北野和梅斯（1998）导致这种关系的独特分析进行了检查，发现了他们的遗漏。 Tayfun (1981) 提出的波峰到波谷的波高分布也经过检验，发现只有当光谱带宽无穷小时才合理。这里对1997年在中国渤海测量的风浪数据进行了分析。探索了测量的（相对于实际的）分布对平滑时间尺度和采样率的敏感性，并对各种理论 pdf 与测量的分布进行了比较。发现 (1) 由 Stansell 等人提出的波高分布。 （2004）和郑等人。 (2004) 其中考虑了负相位导数的贡献，最适合 20 Hz 采样、5 点平滑数据； (2) 忽略负相位导数的贡献，得到最接近 20 Hz 采样、5 或 9 点平滑数据的超过大波高的概率表达式； (3)瑞利分布总体上与我们的数据吻合得很好；与早期观测的差异主要来自于采样率较低； (4) Forristall (1984) 建议采用 Tayfun (1981) 分布来预测超过给定大波高的概率，这与 1.0 ≤ H ≤ 3.0 范围内的 5 点和 9 点平滑数据非常吻合； (5) 改进的波高和周期联合分布，以及 Stansell 等人提出的波周期边缘分布。 （2004）和郑等人。 (2004)对于宽带波的效果并不令人满意。
[1] On the basis of the narrowband approximation the joint and marginal probability distribution functions (pdf) of local wave heights and periods of ocean surface waves have been derived and have been taken approximately as those of the crest-to-trough wave heights and zero upcrossing periods. Various correction schemes have been proposed to these pdf's in order to apply them to broadband waves. This paper is devoted to taking a close look at these correction schemes. The relationship between the distributions of the local and the discrete wave heights and periods is derived at first. This derivation provides a precise interpretation to the improvements due to Stansell et al. (2004) and Zheng et al. (2004). The resultant relationship is different from the one deduced by Kitano and Mase (1998), on which their improved wave height distribution rests. The unique analysis of Kitano and Mase (1998) leading to this relationship is inspected and their omission is found. The crest-to-trough wave height distribution proposed by Tayfun (1981) is also examined and found to be reasonable only when the spectral bandwidth is infinitesimal. The wind wave data measured in Bohai China in 1997 is analyzed here. The sensitivities of the measured (as opposed to actual) distributions to smoothing timescale and to sampling rate are explored and comparisons of various theoretical pdf's with the measured distributions are made. It is found that (1) the wave height distribution due to Stansell et al. (2004) and Zheng et al. (2004) in which the contributions of negative phase derivatives are taken into account fits best with the 20 Hz sampled, 5-point smoothed data; (2) neglecting the contributions of negative phase derivatives results in an expression of the probability of exceeding large wave heights which is closest to the 20 Hz sampled, 5 or 9-point smoothed data; (3) the Rayleigh distribution generally agrees well with our data; the discrepancy between it and early observations mainly comes from the low sampling rate; (4) Forristall's (1984) suggestion of employing Tayfun's (1981) distribution to predict the probability of exceeding given large wave height agrees well with both the 5 and 9-point smoothed data within the range 1.0 ≤ H ≤ 3.0; and (5) the improved joint distribution of wave heights and periods, as well as the marginal distribution of wave periods due to Stansell et al. (2004) and Zheng et al. (2004) are unsatisfactory for broadband waves.