The long-term trend of the sea surface wind speed and the wave height (wind wave, swell, mixed wave) in global ocean during the last 44 a

Utilizing the 45 a European Centre for Medium-Range Weather Forecasts （ECMWF） reanalysis wave da- ta （ERA-40）, the long-term trend of the sea surface wind speed and （wind wave, swell, mixed wave） wave height in the global ocean at grid point 1.5°× 1.5° during the last 44 a is analyzed. It is discovered that a ma- jority of global ocean swell wave height exhibits a significant linear increasing trend （2-8 cm/decade）, the distribution of annual linear trend of the significant wave height （SWH） has good consistency with that of the swell wave height. The sea surface wind speed shows an annually linear increasing trend mainly con- centrated in the most waters of Southern Hemisphere westerlies, high latitude of the North Pacific, Indian Ocean north of 30°S, the waters near the western equatorial Pacific and low latitudes of the Atlantic waters, and the annually linear decreasing mainly in central and eastern equator of the Pacific, Juan. Fernandez Archipelago, the waters near South Georgia Island in the Atlantic waters. The linear variational distribution characteristic of the wind wave height is similar to that of the sea surface wind speed. Another find is that the swell is dominant in the mixed wave, the swell index in the central ocean is generally greater than that in the offshore, and the swell index in the eastern ocean coast is greater than that in the western ocean inshore, and in year-round hemisphere westerlies the swell index is relatively low.

Analysis of the Global Swell Distributions Using ECMWF Re-Analyses Wind Wave Data

The existence of three well-defined tongue-shaped zones of swell dominance,termed as 'swell pools',in the Pacific,the Atlantic and the Indian Oceans,was reported by Chen et al.(2002)using satellite data.In this paper,the ECMWF Re-analyses wind wave data,including wind speed,significant wave height,averaged wave period and direction,are applied to verify the existence of these swell pools.The swell indices calculated from wave height,wave age and correlation coefficient are used to identify swell events.The wave age swell index can be more appropriately related to physical processes compared to the other two swell indices.Based on the ECMWF data the swell pools in the Pacific and the Atlantic Oceans are confirmed,but the expected swell pool in the Indian Ocean is not pronounced.The seasonal variations of global and hemispherical swell indices are investigated,and the argument that swells in the pools seemed to originate mostly from the winter hemisphere is supported by the seasonal variation of the averaged wave direction.The northward bending of the swell pools in the Pacific and the Atlantic Oceans in summer is not revealed by the ECMWF data.The swell pool in the Indian Ocean and the summer northward bending of the swell pools in the Pacific and the Atlan-tic Oceans need to be further verified by other datasets.

Climatology of Wind-Seas and Swells in the China Seas from Wave Hindcast

The wind-sea and swell climates in the China Seas are investigated by using the 27-yr Integrated Ocean Waves for Geophysical and other Applications(IOWAGA)hindcast data.A comparison is made between the significant wave height from the IOWAGA hindcasts and that from a jointly calibrated altimetry dataset,showing the good performance of the IOWAGA hindcasts in the China Seas.A simple but practical method of diagnosing whether the sea state is wind-sea-dominant or swell-dominant is proposed based on spectral partitioning.Different from the characteristics of wind-seas and swells in the open ocean,the wave fields in the enclosed seas such as the China Seas are predominated by wind-sea events in respect of both frequencies of occurrences and energy weights,due to the island sheltering and limited fetches.The energy weights of wind-seas in a given location is usually more significant than the occurrence probability of wind-sea-dominated events,as the wave energy is higher in the wind-sea events than in the swell events on average and extreme wave heights are mostly related to wind-seas.The most energetic swells in the China Seas(and other enclosed seas)are‘local swells’,having just propagated out of their generation areas.However,the swells coming from the West Pacific also play an important role in the wave climate of the China Seas,which can only be revealed by partitioning different swell systems in the wave spectra as the energy of them is significantly less than the‘local swells’.

涌浪对大气边界层风廓线的影响

以往研究表明,涌浪存在时,近海面大气边界层内Monin–Obukhov相似性理论(Monin–Obukhov SimilarTheory,MOST)将会失效,风廓线模型的建立需要考虑波致应力的影响。基于此,本文首先研究了包含涌浪影响的Ekman模型和常通量层模型求解的风廓线。结果表明:两种模型估算的风廓线均对涌浪的波衰减率系数cβ有较高的依赖性,在cβ<–50时,模型求解的风廓线均出现近海面风速极大值,但科氏力对近海面风廓线的影响可以忽略。在不同的大气层结下,分析发现海浪边界层(直接受波浪影响的区域)内风速明显小于海浪边界层之上MOST廓线在相同高度的外推值,体现了涌浪引起明显的剪切增强。通过对比分析广东省茂名市附近海上观测平台的实测数据发现,在涌浪存在时,MOST普遍无法描述风廓线;统计分析表明常通量层模型估算的风廓线在8 m处的风速与实测数据高度一致。考虑以往研究基本局限于中性大气层结条件,而涌浪经常显著影响着浮力作用明显的中低风速条件,我们的研究将有助于理解不同大气层结条件下涌浪对风廓线的影响。

Comparison between wave generation methods for numerical simulation of bimodal seas

This paper describes an investigation of the generation of desired sea states in a numerical wave model. Bimodal sea states containing energetic swell components can be coastal hazards along coastlines exposed to large oceanic fetches. Investigating the effects of long-period bimodal seas requires large computational domains and increased running time to ensure the development of the desired sea state. Long computational runs can cause mass stability issues due to the Stokes drift and wave reflection, which in turn affect results through the variation of the water level. A numerical wave flume, NEWRANS, was used to investigate two wave generation methods： the wave paddle method, allowing for a smaller domain; and the internal mass source function method, providing an open boundary allowing reflected waves to leave the domain. The two wave generation methods were validated against experimental data by comparing the wave generation accuracy and the variance of mass in the model during simulations. Results show that the wave paddle method not only accurately generates the desired sea state but also provides a more stable simulation, in which mass fluctuation has less of an effect on the water depth during the long-duration simulations. As a result, it is suggested that the wave paddle method with active wave absorption is preferable to the internal wave maker option when investigating intermediate-depth long-period bimodal seas for long-duration simulations.

复杂波浪场中防波堤掩护效果的数值模拟研究

防波堤的布局以及波浪的工况条件会使泊位处的波高发生变化,影响系泊船的安全作业。结合南美洲某港口工程,采用基于Boussinesq型方程的MIKE21-BW模型,分析了复杂波浪场中防波堤对泊位的掩护效果,研究不同走向及不同长度的防波堤的掩护性能。结果表明,防波堤布局1在复杂波浪场中具有良好的掩护效果,各种工况中的有效波高均满足短波的波高限制,可以保证船舶的稳泊。但是防波堤布局1并不能对其有效地消解次重力波,随着波浪周期的增大,部分泊位处的次重力波高大于限制标准,可能会存在泊稳问题。布局2的掩护效果欠佳,无法满足限制标准。布局3的掩护效果有了显著的提升,泊位处的有效波高和次重力波高均得到了进一步的消解。研究成果为港口布局、系泊设计和港工建造提供了参考。

穴位敷贴配合空气波压力循环治疗仪对中风偏瘫后肢体肿胀的效果

目的 探析穴位敷贴配合空气波压力循环治疗仪在中风偏瘫后肢体肿胀患者中的实施效果。方法 纳入2022年1月至2023年6月我院收治的中风偏瘫后肢体肿胀患者82例,根据奇偶数字表法将纳入样本分为两组,各41例。对照组实施常规护理和康复指导,观察组实施穴位敷贴配合空气波压力循环治疗仪,比较两组临床效果、患肢周径变化、血液流变学指标、预后恢复情况。结果 观察组临床有效率97.56%较对照组的80.49%高(P <0.05)。干预后,观察组上肢、下肢周径均较对照组更小(P <0.05);观察组血浆黏度(PV)、全血高切黏度(HBV)、全血低切黏度(LBV)、红细胞聚集性(EA)均较对照组更低(P <0.05);观察组美国国立研究院卒中量表(NIHSS)评分较对照组更低,Fugl-Meyer运动功能(FMA)、Barthel指数(BI)较对照组更高(P <0.05)。结论 中风偏瘫后肢体肿胀患者应用穴位敷贴配合空气波压力循环治疗仪,可提升治疗效果,改善患肢周径、血液流变学指标和预后恢复。

长周期波强涌浪海况下自动化移动平台沉桩技术

秘鲁钱凯港工程位于长周期波强涌浪的恶劣海域中,钢管桩数量较多且需无掩护施工,利用传统工艺沉桩较为困难。针对区域海况及工程特点,研发一套装配式自动化移动打桩平台,平台主体由横、竖向钢箱梁通过螺栓法兰盘拼接组成,平台移动由轨道梁+自动化液压油缸顶推系统完成;在平台上安装多个双层抱桩架以稳桩与定位,并为平台的智能运行开发了一套平台自动化监测与控制系统;根据该平台的使用特点提出整套钢管桩平台沉桩工艺。实践证明,该平台及相关工艺解决了恶劣海况下钢管桩沉桩的多重困难,取得了较好的经济效益,可为类似项目提供参考。

基于两种波浪数据的施工船舶可作业预报对比

通过对基于全球海浪预报数据和全球海浪再分析数据的施工船舶可作业预报对比,探讨基于全球海浪预报数据的施工船舶可作业预报的可靠性。针对我国未来海上风电场规划,对2种波浪数据的波浪要素以及采用两种波浪数据的起重船大直径单桩可作业性进行对比,选择具有代表性的17个波浪数据点,在船舶可作业性计算中采用基于时-频域联合计算的方法。结果表明,两种波浪数据中对海上风电施工船舶作业影响较大的波高和波周期的均值和方差误差均较小,总体在10%以内。采用两种波浪数据的可作业性的预报误差不超过15%,大部分可控制在5%以内。表明,海浪预报数据进行施工船舶可作业性的预报依然具有较高的可靠性,可以作为海上风电场整体施工难度评价的依据。

Effects of wind waves of the Pacific westerly on the eastern Pacific wave transport

There exists a tongue-shaped swell-dominance pool known as Swell Pool（SP） in the Eastern Pacific region.The monthly-mean wave transports（WT） for each month of 2000 is computed using the wave products of ECMWF reanalysis data.By comparing the 2000 monthly-mean WT and monthly-mean wind field from QUICKSCAT,large differences are found between the wave transport direction and the wind direction over the Eastern Pacific.This may serve as an evidence for the existence of the SP in this region.The work done in this study indicates that the sources of swell in the Tropical Eastern Pacific（TEP） are in the westerly regions of the Southern and Northern Pacific.

On the Study of Wave Propagation and Distribution in the Global Ocean

Based on the simulation with SWAN wave model and data of ERA-Interim from 1979 to 2016, how the waves propagate globally and why swell pools distribute in the eastern ocean were investigated in this study. The simulation results show that waves from North Pacific and North Atlantic mainly propagate southeastward or southward and swells generated in Southern Ocean spread northeastward. The waves from high latitude regions spread along the east coast and encounter in the tropical Pacific and Atlantic to form swell fronts around equator and then turn eastward. As the weak wind field with numerous swell inflows, swell pools are gener- ally located on the eastern side of the ocean basin, where the swell index S are greater than 0.9 calculated using ERA-20C data for the period of 1981 2010. Another remarkable feature is that swell pools move southward and split into two parts in winter, while they move northward and merge together in summer.

A laboratory study of directional spectrawith maximum likelihood mehod─ⅡDecaying swell

From measurements by a circular array consisting of 18 wave gauges in a large wave tank, directional spectra of swell in deep water are systematically investigated with maximum likelihood method. It is shown that the directional spreading of swell, qualitatively similar to that of developing wind wave which is narrowest in the region of Peak frequency and bxoadens with increasing or decreasing frequency, can be effectively described by cos2s(θ/2) introduced by Longuet-Higgins et al. (1963,Ocean Wave Spectra, 111~136). It is intriguing that bimodal distribution found in our experiments appers at the forward face instead of the rear face of a frequency spectrum in the cases of nonlinearity being very weak. Parameterized by nonlinearity, formulations which can be applied to swell as well as wind wave are proposed. It is concluded that nonlinear interaction plays a central role in controlling the development of directional angular spreading even for the swell.

Variations in Swells along Eastern Arabian Sea during the Summer Monsoon

A study was carried out to find the variation in wave characteristics along the eastern Arabian Sea and the influence of swells in the nearshore waves at 3 locations during summer monsoon in 2010. Percentage of swells in the measured waves was 75% to 79% at the locations with higher percentage of swells in the northern portion of Arabian Sea com-pared to that at the southern side. The significant wave height up to 4.7 m and maximum wave height up to 7.4 m was observed. The wave height was increasing from south to north with the average significant wave height at the northern location 20% more than that at the southern location due to the increase in the swell height. Waves having spectral peak period less than 6 s were not present during the summer monsoon period. There was no change in the average value of wave statistical parameters for data collected at 1/2, 3, 6, 12 and 24 h interval.

基于ERA5海浪再分析数据的风浪涌浪分离方法

为了探究和分析海浪中的主要成分,本文基于ERA5海浪再分析数据,依据能量因子分离风、涌浪的原理,研究了风、涌浪的平均波周期与风速的分布规律。利用最小二乘拟合方法,提出了一种分离风、涌浪的方法,并将其命名为TU方法。通过将TU方法与波龄方法进行比较分析,验证TU方法的可行性和可靠性。结果显示:在本文的研究区域中,TU方法与波龄方法识别风浪的正确率为98.57%和98.55%,TU方法与波龄方法识别涌浪的正确率为78.9%和65.1%,表明根据风速与平均波周期2个参数识别涌浪,TU方法效果比波龄方法更好。对高度计等缺少风向信息情况下分离风浪与涌浪有着重要的意义。

Numerical simulation and preliminary analysis of typhoon waves during three typhoons in the Yellow Sea and East China Sea

In this study,typhoon waves generated during three typhoons(Damrey(1210),Fung-wong(1416),and Chan-hom(1509))in the Yellow Sea and East China Sea were simulated in a simulating waves nearshore(SWAN)model,and the wind forcing was constructed by combining reanalyzed wind data with a Holland typhoon wind model.Various parameters,such as the Holland fitting parameter(B)and the maximum wind radius?,were investigated in sensitivity experiments in the Holland model that affect the wind field construction.Six different formulations were considered and the parameters determined by comparing the simulated wind results with in-situ wind measurements.The key factors affecting wave growth and dissipation processes from deep to shallow waters were studied,including wind input,whitecapping,and bottom friction.Comparison with in-situ wave measurements suggested that the KOMEN scheme(wind input exponential growth and whitecapping energy dissipation)and the JONSWAP scheme(dissipation of bottom friction)resulted in good reproduction of the significant wave height of typhoon waves.A preliminary analysis of the wave characteristics in terms of wind-sea and swell wave revealed that swell waves dominated with the distance of R to the eye of the typhoon,while wind-sea prevailed in the outer region up to six to eight times the R values despite a clear misalignment between wind and waves.The results support the hypothesis that nonlinear wave-wave interactions may play a key role in the formation of wave characteristics.

涌浪作用下港内大型集装箱船运动特性数值研究

随着船舶大型化和港口建设深水化发展,外海不同周期波浪作用下大型系泊船泊稳问题与小型系泊船相比出现了新的特点。为此,利用数值模型方法研究了在不同入射角度和周期的涌浪作用下港内大型系泊船的水动力响应,针对系泊船的泊稳情况探讨了船舶的运动规律和运动特性。研究发现,在涌浪周期较大的情况下,限定波高的泊稳标准不足以用来确定系泊船的正常作业条件,港内泊船的水平运动(纵荡、横荡和艏摇)极易超出运动标准值并影响装卸作业效率,并且船舶的水平运动表现出主要由次重力波主导的低频运动特性,而垂直运动(垂荡、横摇和纵摇)表现出主要由短波主导的波频运动特性。

Investigation of wave characteristics in a semi-enclosed bay based on SWAN model validated with buoys and ADP-observed currents

In this study, the simulating waves nearshore (SWAN) model with a locally refined curvilinear grid system was constructed to simulate waves in Jervis Bay and the neighbouring ocean of Australia, with the aim of examining the wave characteristics in an area with special topography and practical importance. This model was verified by field observations from buoys and acoustic Doppler profilers (ADPs). The model precisions were validated for both wind-generated waves and open-ocean swells. We present an approach with which to convert ADP-observed current data from near the bottom into the significant wave height. Our approach is deduced from the Fourier transform technique and the linear wave theory. The results illustrate that the location of the bay entrance is important because it allows the swells in the dominant direction to propagate into the bay despite the narrowness of the bay entrance. The wave period T p is also strongly related to the wave direction in the semi-enclosed bay. The Tp is great enough along the entire propagating direction from the bay entrance to the top of the bay, and the largest Tp appears along the north-west coast, which is the end tip of the swells’ propagation.

强涌浪条件下防波堤掩护效果数值模拟研究

处于涌浪环境的港口可能会遇到防波堤掩护效果不理想和港湾振荡问题。以秘鲁钱凯湾的某海港工程为依托,通过数值模拟分析了涌浪作用下的防波堤掩护效果和港湾振荡特性。结果表明,防波堤对于涌浪具有较好的掩护效果,港内波高与港外波高的比值约0.15。根据短波的波高限制标准,港口的泊稳条件可以得到保证。次重力波传入港内后几乎没有衰减。根据次重力波的限制标准,港口可能会存在泊稳问题。在进行港口布局和系泊船系泊布置设计时,应考虑次重力波的影响,特别是应避免系泊系统的固有周期接近港内次重力波的周期。研究结果可为港口布局和系泊系统的设计提供参考。

基于二维海浪谱的风涌浪分离方法研究

海浪通常以风浪和涌浪混合的形式存在。二者的成长、消衰、传播和破坏机制各不相同,实现风涌浪分离对海洋研究和工程应用具有重要意义。基于斯里兰卡汉班托塔海域的实测数据,讨论了传统波龄法中波龄阈值的选取问题,并对汉班托塔海域的海浪特征进行分析,最后利用波龄法对新提出的不依赖风速风向信息的超射法进行了研究。结果表明,波龄阈值取1.7时最为合理。汉班托塔海域为外海涌浪主导。超射法对外海涌浪的识别结果与波龄法一致,而对高频位置的风浪和局地涌浪给出了不同的结果,这主要是由海浪物理特性的改变慢于风速风向的变化引起。

斯里兰卡南部海域次重力波特征研究

次重力波在近岸水动力运动过程中起到重要作用,深入地了解次重力波对预防其引发的近岸灾害有着重要意义。结合波浪现场观测方法和数值模拟方法研究了斯里兰卡南部海域次重力波特征。短波和自由次重力波通过海浪谱模型WAVEWATCH III模拟,而约束次重力波通过二阶非线性理论模拟,数值模拟结果与现场观测结果对比吻合良好。研究结果表明,斯里兰卡南部海域大部分时间以自由次重力波为主;在强涌浪海况下(短波波高大于2.5 m,周期大于15 s)约束次重力波逐渐逼近自由次重力波甚至占主导地位;斯里兰卡大陆架极其狭窄,对涌浪的能量损耗作用极为有限,使得近岸面对强劲的涌浪及其伴生的次重力波的侵袭,增大了次重力波引发近岸水动力灾害的风险。