关于Bretschneider风浪频谱的注记

依据作者提出的海浪能量外观分布，即外频谱的概念，重新推导了Ｂｒｅｔｓｃｈｎｅｉｄｅｒ风浪谱，极大地简化了Ｂｒｅｔｓｃｈｎｅｉｄｅｒ原来的推演过程，并对谱的系数予以订正，将订正后的Ｂｒｅｔｓｃｈｎｅｉｄｅｒ和Ｍｏｓｃｏｗｉｔｚ谱进行了比较，结果表明，两种风浪频谱在数学表述上是完全等价的。     

华南沿岸浅水台风风浪频谱的初步探讨

在深水海浪向近岸浅水区传播的过程中,由于变浅作用,海浪的频谱发生了相应的变化。文章以华南沿岸实测浅水台风风浪资料为基础,通过分析比较深水风浪频谱与实测台风风浪频谱的不同,并对实测资料进行统计处理,得出适用于华南沿岸浅水台风风浪的频谱。文章还将该频谱与已有的两种深水风浪频谱和Basinski－Massel浅水风浪频谱进行了比较。     

华南沿岸浅水台风风浪频谱的初步探讨

在深水海浪向近岸浅水区传播的过程中,由于变浅作用,海浪的频谱 相应的变化。章以华南沿岸实玫水台风风浪资料为基础,通过分析比较深水风浪频谱与实测台风风浪频谱的不同,并对实测资料进行统计处理,得出适用于华南沿岸浅水台风风浪的频谱。章针该频谱与已有的两种深 浪频谱和Ｂａｓｉｎｓｋｉ－Ｍａｓｓｅｌ浅水风浪频谱进行了比较。     

有限水深的风浪频谱

基于三参量（Ｂ，ｍ０，ω０）风浪频谱，经变换引进了深度参量μ，通过解出传统谱出的Ｋ，Ｆ，ｐ，ｑ与Ｂ，ｍ０，ω０，μ间的关系，得到了有限水深海浪频谱，从而使传统频型具有完备的形式。本文还给出一种由深水海浪谱构造浅水海浪谱的方法。     

以海浪波要素表示的外频谱形式

孙孕等（１９９４）提出了外频谱的概念,并推导出外频谱的理论形式,但其控制参量是由内频谱导出的,不便于实际应用,通过对实测海浪数据的分析,得到了控制外频谱的３个和内频谱有关的参量与波浪要素之间的关系,进而将外频谱表示以有效波高和有效波周期作为控制参量的形式,应用实测资料将本文得到的外频谱形式与理论外频谱进行了比较,发现二者符合良好。     

风浪频谱中的特征量

在三参量风浪频谱的基础上对谱参量进行深入地研究,给出了谱参量与风场要素、波场要素的关系,提供了依据风场要素、波场要素及实测波浪资料计算谱参量的方法。从而可以依据上述因素直接计算出三参量风浪频谱。此外还根据谱宽度的变化,描述了风浪频谱的成长方式,解释了传统的波陡、波龄关系中经验常数的不同选取所代表的物理背景。     

三参量的风浪频谱

本文基于风浪由单色波发展为充分成长状态的物理背景,阐明了一种描述谱形变化的谱宽度参量,进而确立了三参量风浪频谱的理论形式。在传统谱形的基础上,通过谱宽度参量的引入而建立了随成长状态变化的形式更为普遍的风浪频谱,在此频谱中不仅包括Neumann谱、P-M谱、JONSWAP谱、Wallops谱等重要的风浪频谱,而且还在谱的高频部分比例于频率的-4次方的假定下,导出另外一种风浪频谱。同时本文还为构造新谱提供了一种方法。     

分形与风浪频谱

用变维分形方法分析了实测谱值符合良好的Ｈｏｎｇ－Ｙａｎｇ谱，根据分析结果讨论了用分形方法测谱值的拟合与插值，效果很好。文中还证明，种种形式的风浪频谱均可转化为变维分的形式。     

风浪频谱的成长模型 Ⅱ.三参量的风浪频谱随风区的增长关系

为研究三参量风浪频谱随风浪的成长关系,从而直观地描述风浪频谱成长过程中的超射现象.并证明三参量谱谱型的合理性.基于已得到的谱参量随风区的变化关系,对三参量风浪频谱以及风浪频谱成长过程中存在的"超射"现象作深入的研究,得到三参量风浪频谱随风区的成长关系:S(-ω,-m0,-ω0,B)=-m0(-x)/-ω0(-x)B(-x)[-ω/-ω0(-x)]-p(x)exp[-p(-x)/q(-x)([ω/ω0(-x)]-q(-x)-1)]在此基础上,得到无因次风区:300、500、2000、5500、10000、15000下,风浪频谱的谱线,从而直观地描述了风浪频谱成长过程中的"超射"现象,并认为在风浪频谱的成长过程中确实存在着"超射"现象,但是该现象并不如Hasselmann等提出的理论中阐述的那样存在于风浪频谱成长的全过程,而是仅存在于风浪频谱成长的初期.随着风浪的不断成长,"超射"现象逐渐减弱,直到风浪接近充分成长,"超射"现象也随之逐渐消失.经过不同风区下实测数据的检验,证明S(ω,-m0,-ω0,B)、S(ω,-H,-T,B)、S(ω,-H,-T,-δ)以及S(ω,-H,-T,β)四种形式的三参量风浪频谱谱型是合理的,同时也进一步证明了谱的零阶矩、谱的峰频率、谱宽度、波高、周期、波陡和波龄随风区变化关系的正确性.     

风浪和涌浪分离方法的比较（英文）

海浪通常以风浪和涌浪混合的形式存在,如何进行分离风浪和涌浪一直是海浪理论研究和海洋工程应用中的重要问题。本文利用模型试验和实测资料,对目前提出的一种二维谱风涌浪分离方法（2D法）和三种一维谱风涌浪分离方法（PM法、WH法、JP法）进行了检验,分析发现：2D法给出的结果整体而言最为可靠,与2D法相比,PM法明显高估了风浪成分,WH法低风速时高估了风浪,高风速时跟2D法比较接近,而JP法在整体上高估了风浪成分。通过调整分割频率的比例系数,改进了PM法,改进后的PM法给出的分离结果与2D法最为一致。     

Estimation of Wind Wave Frequency Spectra by Use of the Arcsine Law

In the present study,the surface elevation of wind waves oberved in laboratory and in the Bohai Sea are adopted for the estimation of the wind wave frequency spectrum by use of the method of the arcsine law(MAL).The traditional method uses the surface elevation to calculate the correlation and then estimate the frequency spectrum while the MAL,presented by Yu and Lan(1979),uses the time sequence of zero-crossing points of surface elevation rather than directly the surface elevation to calculate the correlation.66 sets of wind wave data obtained in laboratory and 420 sets of data observed in the Bohai Sea are adopted for the examination of the method introduced by Yu and Lan.Results show that the MAL can give reliable estimation of wind wave spectra.Correlation and form of spectra estimated by the MAL are similar to those estimated by the traditional method.The peak frequency and the spectral density in peak frequency by the MAL are close to those obtained by the traditional method.     

Radar Investigation of the Structure of Wind Waves

Radar data from three experiments are analysed. Scatter characteristics of 50 cm wind-generated waves have been investigated with a C-band radar in a large wind-wave tank. Evidence of wave groups in sea clutter from the west coast of Scotland in the Sound of Sleat is also presented. The spectrum of the waves in the sound is narrow-banded and the waves are young, like the wind-wave spectrum in the laboratory. Clutter measurements, collected on the English south coast at Portland, of more ocean-like waves with broad band spectra also suggest the presence of wave groups. Evidence of the presence of wave groups is demonstrated in range-time images, as well as in the Fourier domain. Some ad hoc processing schemes, the normalised variance and binary threshold techniques, were successfully applied to enhance the appearance of the wave groups. The wind waves change frequency with fetch in the wave tank and the downshifting process is investigated using range-frequency maps of the radar data. The waves appear to change frequency in discrete steps that are associated with wave breaking events. The difference in wave period before and after breaking could be measured, and a wave crest was shown to be lost to compensate for the change in period, as expected. Some downshifting could also be measured in the Sound of Sleat. The ratio of wave group frequency and wave frequency is inaccordance with Benjamin-Fier sideband instability theory, as it is for the data measured at Portland. This revised version was published online in July 2006 with corrections to the Cover Date.     

Improvement and application of a saturation based wave dissipation function in SWAN model

Wave dissipation characteristics in SWAN (Simulating Waves Nearshore) model are investigated through numerical experiments. It is found that neither the fully developed integral parameters of wind waves (significant wave height and peak frequency) nor the high frequency spectral tail can be well reproduced by the default wave dissipation source terms. A new spectral dissipation source term is proposed, which comprises saturation based dissipation above two times of peak frequency and improved whitecapping dissipation at lower frequency spectrum. The reciprocal wave age (u /c p ) is involved into the whitecapping model to adjust dissipation rate at different wind speed. The Phillips higher frequency saturation parameter in the saturation-based dissipation is no longer taken as a constant, but varies with wave age. Numerical validations demonstrate that both the wind wave generation process and higher frequency spectrum of wind waves can be well simulated by the new wave dissipation term.     

Composite Type Wind Wave Frequency Spectrum

Based on the P-M spectrum and improved theoretical wind wave frequency spectrum, this paper presents the composite type wind wave frequency spectrum, which is given by 2 pieces and satisfies 4 conditions: the spectrum peak passes through a given point; spectral area m0 and significant wave height H have the relationship H = 4.0 ; at the piecewise point, the values of spectrum and slope are contin-     

海浪外观统计与内部结构关系的数值研究

基于数值模拟的三维随机海面,从时间域和空间域两个角度对海浪的外观特征和内部结构间的关系进行了研究,得出了一些在工程应用上有参考价值的结果.文章认为,将波面看作是若干随机正弦波叠加的海浪结构模型,用于描述平稳、均匀和窄谱的海况时,其频谱分析结果与外观统计结果基本上是一致的;但是,当海面处于谱宽度较大的风浪或混合浪状态时,一些频谱分析结果必须经过修正才能应用.同一海况下,海面波动的时间过程和沿主波向的空间分布是明显不同的.当海面有突发性大浪时,外频谱能够很好地反映不平稳海况,而频谱则把这种不平稳性平滑了.文章着重讨论了波长和波陡的计算、频谱和外频谱的差异.     

涌浪对风浪能量影响的实验研究

在实验室风浪水槽中进行纯风浪和混合浪波面位移观测,研究波长较长的规则波对风浪能量的影响.本文用混合浪和纯风浪中的风浪显著波的零阶谱矩之比代表混合浪中的风浪与纯风浪能量之比,并以此表征涌浪对风浪能量的影响.研究了该能量比随涌浪波陡S、风区x、波龄倒数u/C、涌浪频率与纯风浪谱峰频率之比fs/fwp的变化规律.结果表明,涌浪对风浪能量的抑制作用随涌浪波陡的增加、波龄倒数的增大及涌浪频率与纯风浪谱峰频率之比的增大而增强.发现该能量比依赖于无因次量R=(1+80(πS)2)1.9(fs/fwp)0.9(u/C)0.27,并拟合得到2者的经验关系.此外,本文实验还发现,在某些情况下,涌浪的存在使风浪能量增加.     

Numerical Simulated Study on the Separation of Oblique Incident and Reflected Waves

The Goda's method of separating the frequency spectrum of the unidirectional incident and reflected waves is improved. The proposed method can be applied to the separation of oblique incident and reflected waves and the two wave gauges can be arranged in an arbitrary angle in front of a structure. When the projected distance of the two probes on the incident wave direction is the multiple ofthe half length of the incident waves, the singular problem will emerge by using the method. It is advised that when the projected distance of the two measured points on the incident wave direction is 0.05～0.45 times the wave length of peak frequency wave, good results can be obtained. The simulated resultant waves are separated by the method of numerical simulation and the separated wave spectra are basically corresponding to the target spectra input. The wave trains calculated by the separated incident and reflected wave frequency spectrum are approximated to the input wave trains and the reflected coefficient can be derived correctly. Therefore, the method proposed in this paper is reliable.     

基于人工神经网络的高频雷达风速反演

风速是重要的海洋状态参数之一，对海面风速的准确提取是实现海洋环境监测和沿海工程应用的重要保证。目前，作为新兴海洋环境监测设备，高频雷达在风速提取方面仍然存在挑战。本文提出了一种基于人工神经网络的风速提取方法，利用历史浮标测量海态数据训练风速提取网络，实现风速与有效波高、波周期、风向及时间因素之间的非线性映射。测试结果表明了这一网络在时间和空间上的稳定性；进而将已训练的网络应用到便携式高频地波雷达OSMAR-S的风速反演中，得到的风速与浮标测量风速间的相关系数达到0.849，均方根误差为2.11 m/s。这一结果明显优于常规由浪高反演风速的SMB方法，验证了该方法在高频雷达风速反演中的可行性。     

On the Spectrum Width of Wind Waves

Based on the universal expression of wind wave spectra, four commonly used definitions of the spectrum width are re-examined. The results show that the non-dimensional spectrum width can measure the width of non-dimensional spectra hut it does not reflect the developing state of the spectra. The dimensional spectrum width expresses the degree of concentration of wave energy of the spectrum in (he process of wind wave growth. Tests show that the spectrum width presented by Wen et al. can objectively measure the degree of concentration of wave energy of the spectrum, reflect the state of wind wave growth, and provides a better result for practical application. The rules for definition of the spectrum width are discussed.