舟山群岛海域波浪对泥沙冲淤过程的影响

本文基于SWEM(Shallow Water Equation Model)三维水沙盐模式,考虑潮汐、径流、风场和波浪影响,在长江口与杭州湾及其邻近海域建立了一个高分辨的三维水沙盐模型。分析了一般天气条件下,舟山群岛海域在潮汐、径流、风场、波浪共同作用下的地形冲淤与悬沙含量分布特征,并对比分析了一般天气条件下与台风天气条件下波浪对泥沙冲淤过程的影响。一般天气条件下,舟山群岛海域东西向水道为冲刷特征,舟山群岛东侧海域以及舟山群岛内部南北向水道为淤积特征。舟山群岛海域暖半年冲刷增强,冷半年淤积增强。海域悬沙含量由西北向东南迅速降低,群岛“虑沙”效果明显。悬沙含量3月份最大,8月份最小。波浪对舟山群岛海域泥沙冲淤过程的总体影响在秋冬季较强,春夏季较弱。一般天气条件下与台风天气条件下,波浪对研究海域泥沙冲淤过程影响显著的区域均为朱家尖东侧海域,且波浪的影响特征均表现为促进淤积和增加悬沙含量。一般天气条件下波浪引起最大淤积约占总淤积量的10%。台风天气条件下波浪引起的淤积量约是同时段一般天气条件下的6倍。     

波浪作用下细颗粒泥沙悬移特性的试验研究

通过9组室内水槽试验,系统分析了不同周期和波高波浪作用下粉砂质细砂的悬移特性。试验结果表明,在波浪作用下,细颗粒泥沙在水体中悬浮产生明显的三层混浊结构：近底高浓度混浊层、中部混浊层和上部低浓度混浊层。其混浊度的大小与波浪动力条件相关,波浪周期的延长和波高的增加都会使近底层悬沙浓度显著增大,悬沙浓度的波动性在近底层表现得最为突出和复杂;波浪动力条件的改变对上层水体的悬沙浓度基本不产生影响。当波浪作用停止,悬沙开始静水沉降时,近底层水体含沙浓度的变化与波浪要素的比值相关,当波浪要素的比值大于临界值时,底层含沙浓度在一定时间段内反而增加,出现浓度返起现象。     

青岛近海悬沙输运的三维数值模拟

研究近海海域水流、悬沙运动规律,运用基于COHERENS发展的水动力悬沙模型COHERENS-SED,结合当地一般波浪条件,模拟了青岛近海悬浮泥沙输运情况,并验证及分析了水动力环境及悬沙输运的模拟结果。结果表明：在波流合作用下,近岸掀沙明显,大潮期间该海域近岸悬沙浓度值最高可达50mg／L。     

东碇倾倒区疏浚泥悬沙输移和海床冲淤数值模拟

采用区域海洋模型ROMS(Regional Ocean Modeling System)在东碇倾倒区建立三维水动力与泥沙输移数值模型,在水动力验证的基础上模拟预测了在冬、夏季节不同背景潮流和风场作用下的疏浚泥悬沙输移规律及海床沖淤变化。结果表明:在纯潮流作用下,悬沙扩散以抛泥点为中心,呈圆对称分布,且冬季泥沙输移扩散范围比夏季大;加入风场驱动后,悬沙扩散呈下风面拖拽的椭圆形,同时水体混合加强更有利于高浓度悬沙的扩散,但对悬沙输移的作用不明显;抛泥点位置从倾倒区中心变为西北角后,其作用主要体现在冬季较高浓度区面积的减小和由于局地水槽引导而形成的向北延伸的浓度舌;在海床冲淤方面,潮流和风场的作用主要是改变地形增量较大的面积,而更改抛泥点位置则会导致地形增量最大值出现较大的差异。     

桐花树红树林潮滩近底层悬沙浓度垂向剖面变化特征分析*

观测红树林潮滩在波浪和潮流作用下的近底层垂向剖面悬沙浓度变化过程, 对理解海岸带植被的消能促淤机制和滨海湿地生态修复工程有着重要作用。本文以北部湾七星岛岛尾桐花树红树林潮滩为例, 基于剖面流速仪HR、声学多普勒单点流速仪ADV、浪潮仪T-wave及剖面浊度仪ASM, 获取了研究区域2019年夏季大潮连续3天的水文数据, 同时结合桐花树典型植株实测参数, 分析了潮周期内红树林潮滩近底层垂向剖面悬沙响应波浪、潮流作用及桐花树空间结构的运动过程。结果表明: 1) 桐花树潮滩近底层悬沙浓度和悬沙通量具有涨潮明显大于落潮的潮汐不对称现象, 剖面垂向高悬沙浓度区域在涨潮初期—涨急由距底部0.1~0.37m转变为距底部0.5~0.67m, 落急—落潮末期则由上部转变为下部; 2) 潮周期内悬沙起动和再悬浮阶段发生在以波浪作用主导的涨潮初期和落潮末期, 平流和沉降发生在以潮流作用为主的涨急至落急整个阶段; 3) 涨潮阶段桐花树冠层的茂密枝叶通过减缓流速拦截多于冠层上部40%以上的悬沙, 落潮水体则挟沙自陆向海经过桐花树群落, 使得悬沙浓度下降超过71%。该不对称涨、落潮动力沉积机制有利于悬沙向岸输运, 促进潮滩扩张过程。     

黄渤海水体交换、悬沙特征及其对渤海海峡沉积的影响

根据渤海潮流、环流和悬沙浓度特征，黄海水体由渤海海峡北部输入渤海，在渤海循环后，经由渤海海峡南部输出到北黄海。输出水体的悬沙浓度达到0.01kg/m^3的量级，远高于输入水体。因此，黄、渤海水体交换的结果是悬沙向北黄海输出。渤海海峡南部是高悬沙浓度区，又是渤海水体输往北黄海的通道，因而渤海海峡楔状堆积体似乎是截留部分悬沙并发生堆积的结果。但是，渤海海峡水动力条件和沉积物分布特征均不支持这个假说。楔状堆积体的主体部分可能是在全新世高海面以前就形成了，而其物质可能是来源于海面上升过程中的海底物质改造和局部的海岸侵蚀。要弄清渤海海峡楔状堆积体的成因和物质来源，还需深入研究堆积体的表层沉积速率、泥碳的年龄、泥质沉积区的动水沉降通量、以及浅地层剖面层序。     

北部湾南部海域近底悬沙输运及地貌演变

利用1个海洋沉积动力过程原位监测系统在北部湾南部浅海陆架海域采集了18个潮周期的波浪、潮流、悬浮沉积物浓度、底床变化数据,分析了悬沙浓度变化特征,计算了近底悬沙通量并分析了潮流和波浪对底床演变的影响,结果表明:观测期间近底悬沙浓度的变化主要受水位波动、潮流的共同影响,波浪作用较弱;悬沙浓度的异常高值可能是上游沙波表面的泥沙滑落沉降所致;观测期间悬沙通量的波动规律与近底潮流速度变化一致,潮周期和涨落潮之间的悬沙通量有显著差别;在潮流作用下观测期间悬沙向西的净输运量约为15 158 kg/m,向北净悬沙通量为2 934 kg/m,东西向净通量远大于南北向净通量;近东西向波谷地形对南北向悬沙输运的限制作用可能导致了输运通量的显著差异;底床高程的变化在潮周期之间有差异,变化值在0.8~16.7 cm之间波动,厘米级底床高程的快速变化主要是由潮流流速的大小及往复潮流的不对称性造成的。这种变化可能与沙纹的运移有关,沉积物向下游方向的运移以及沙纹剖面形态的改变可以较合理地解释底床高程的变化特点。     

北部湾南部海域近底悬沙输运及地貌演变

利用1个海洋沉积动力过程原位监测系统在北部湾南部浅海陆架海域采集了18个潮周期的波浪、潮流、悬浮沉积物浓度、底床变化数据,分析了悬沙浓度变化特征,计算了近底悬沙通量并分析了潮流和波浪对底床演变的影响,结果表明:观测期间近底悬沙浓度的变化主要受水位波动、潮流的共同影响,波浪作用较弱;悬沙浓度的异常高值可能是上游沙波表面的泥沙滑落沉降所致;观测期间悬沙通量的波动规律与近底潮流速度变化一致,潮周期和涨落潮之间的悬沙通量有显著差别;在潮流作用下观测期间悬沙向西的净输运量约为15 158 kg/m,向北净悬沙通量为2 934 kg/m,东西向净通量远大于南北向净通量;近东西向波谷地形对南北向悬沙输运的限制作用可能导致了输运通量的显著差异;底床高程的变化在潮周期之间有差异,变化值在0.8~16.7 cm之间波动,厘米级底床高程的快速变化主要是由潮流流速的大小及往复潮流的不对称性造成的。这种变化可能与沙纹的运移有关,沉积物向下游方向的运移以及沙纹剖面形态的改变可以较合理地解释底床高程的变化特点。     

华南不同类型热带风暴驱动下珠江口表层悬沙分布趋势

本文利用1949—2014年的华南热带风暴数据和1960—2014年珠江入海流量等, 统计分析风暴作用期间珠江口的风强迫和珠江入海水沙强迫特征, 结果表明, 热带风暴对珠江口的风强迫和水沙强迫因台风距珠江口的距离、强度等因素的影响有显著差异。依据水沙及风强迫的强度, 将热带风暴对珠江口的影响简单分成四类: 中风中水沙驱动型、中风高水沙驱动型、强风中水沙驱动型及强风高水沙驱动型。利用MODIS (moderate-resolution imaging spectroradiometer)一级数据和已建立的珠江口表层悬沙指数反演模型, 挑选2002—2010年风暴影响期间无云天气的MODIS影像, 反演珠江口悬沙分布, 分析表层悬沙对四种不同来水来沙及风强迫型风暴的响应特征。结果显示, 中风中水沙型风暴驱动下, 珠江口整体含沙量偏低, 其悬沙扩散及时间变化受控于潮流的强弱; 中风高水沙型风暴驱动下, 八大口门特别是磨刀门浅滩、伶仃洋西滩的含沙量高于其他海域, 其高含沙水体向南偏西方向扩散输运; 强风中水沙风暴驱动下, 河口表层悬沙分布及扩散受主导风向的影响, 在强东北风驱动下, 伶仃洋西侧浅滩含沙量因台风浪的掀沙作用高于湾内大部分海域, 高含沙水体向西南侧扩散; 强风高水沙风暴驱动下珠江河口湾含沙量偏高, 水体一片浑浊, 河口悬沙随偏南风驱动下的沿岸流向东侧输运、扩散。     

潮流、波浪综合作用下河口二维悬沙数学模型

本文根据河口水流动力特性和泥沙变化规律，把波浪运动概化为具有时均意义的波浪流分布场，将“波流幅射应力”、“波流摩阻力”以及“波流挟沙力”三个要素归纳到水流运动方程和悬沙输送方程中去，构成潮流、波浪综合作用下河口二维悬沙数学模型计算系统。通过对珠江口黄茅海悬沙冲淤过程的实际算例，表明该系统模拟河口悬沙在潮流和波浪综合作用下的分布特性和冲淤趋势方面，具有良好的应用前景。     

波流耦合作用下渤海及北黄海风暴潮增水及海浪过程的数值模拟

本文基于三维波流耦合FVCOM-SWAVE数值模式,采用Jelesnianski参数化风场与再分析数据集ECMWF风场数据叠加而成的合成风场作为外力驱动力,模拟了1818号"温比亚"台风引起北黄海及渤海海域风暴潮增减水及波浪的生长与消减过程,进而分析该海域在"温比亚"台风作用下波浪对流速垂向分布的影响。研究结果表明:合成风场得到的风速最大值及出现时刻与实测数据符合较好,合成风场较为合理,能够为模拟波流耦合机制下海域水动力变化提供准确的风场条件;几个测站的风暴潮增水模拟结果与实测数据较为吻合,FVCOM-SWAVE耦合系统合理地再现了"温比亚"台风在黄渤海引发的风暴潮增水以及台风浪过程。此外,计算结果显示"温比亚"期间黄渤海海域最大有效波高分布于台风中心外围,且位于台风前进方向上,波浪最大有效波高值与台风强度有关;在台风过境期间,波流相互作用对近岸海域流速的垂向分布具有一定影响,考虑波流相互作用可有效提高台风风暴潮数值模拟精度。研究结果对台风灾害预报、防灾减灾及港口建筑选址具有一定的参考意义。     

Wave model predictions in the Black Sea: Sensitivity to wind fields

This paper evaluates the impact of using different wind field products on the performance of the third generation wave model SWAN in the Black Sea and its capability for predicting both normal and extreme wave conditions during 1996. Wind data were obtained from NCEP CFSR, NASA MERRA, JRA-25, ECMWF Operational, ECMWF ERA40, and ECMWF ERA-Interim. Wave data were obtained in 1996 at three locations in the Black Sea within the NATO TU-WAVES project. The quality of wind fields was assessed by comparing them with satellite data. These wind data were used as forcing fields for the generation of wind waves. Time series of predicted significant wave height (H_mo), mean wave period (T_m02), and mean wave direction (DIR) were compared with observations at three offshore buoys in the Black Sea and its performance was quantified in terms of statistical parameters. In addition, wave model performance in terms of significant wave height was also assessed by comparing them against satellite data.The main scope of this work is the impact of the different available wind field products on the wave hindcast performance. In addition, the sensitivity of wave model forecasts due to variations in spatial and temporal resolutions of the wind field products was investigated. Finally, the impact of using various wind field products on predicting extreme wave events was analyzed by focussing on storm peaks and on an individual storm event in October 1996. The numerical results revealed that the CFSR winds are more suitable in comparison with the others for modelling both normal and extreme events in the Black Sea. The results also show that wave model output is critically sensitive to the choice of the wind field product, such that the quality of the wind fields is reflected in the quality of the wave predictions. A finer wind spatial resolution leads to an improvement of the wave model predictions, while a finer temporal resolution in the wind fields generally does not significantly improve agreement between observed and simulated wave data.     

SIMULATION OF WIND FIELD AND THE NUMER-ICAL CALCULATION OF STORM SURGE OF THE BOHAI SEA

Up to now, available method of numerical forecasting and suitable wind field model for the Bohai Sea storm surge have been few. In this paper, through the analysis of the weather situation is presented a mathematical model for the wind fields involved mainly the deformation field of a high pressure matched with a low pressure, the temperate cyclone, the cold wave and the northword typhoon. Meanwhile, numerical computations combined with the nonlinear storm surge models are made by using "ADI" method. The computed results are generally coincident with the practical observations. It has showed a success in the simulated wind field and the feasibility of using "ADI" method to forecast the Bohai Sea storm surge.     

浪潮耦合的舟山渔港台风暴潮数值模拟

建立能精确模拟舟山渔港台风暴潮过程的浪潮耦合模型,对渔港防灾减灾具有重要意义。基于Delft3D中的FLOW和WAVE模块,在二重嵌套网格下建立风暴潮和波浪的耦合模型。以9711号台风Winnie为背景,验证耦合模型的可靠性,结果显示,风速、天文潮潮位、风暴潮潮位和有效波高的计算值与实测值吻合良好。利用风暴潮模型与耦合模型分别计算了舟山海域的风暴潮,分析了波浪对风暴潮潮位的抬升影响,定海和镇海站最大波浪增水分别为23 cm和34 cm,耦合模型的模拟精度要高于风暴潮模型。通过模拟9711号台风期间舟山渔港的风暴潮过程,分析了风暴潮的时空分布特征,并给出了浪潮耦合作用对于风暴潮时空分布的影响。     

Simulation of Typhoon-Driven Waves in the Yangtze Estuary with Multiple-Nested Wave Models

Typhoon-generated waves are simulated with two numerical wave models, the SWAN model for the coastal and Yangtze Estuary domain, nested within the WAVEWATCHIII （WW3） for the basin-scale East China Sea domain. Typhoon No. 8114 is chosen because it was very strong, and generated high waves in the Estuary. WW3 was implemented for the East China Sea coarse-resolution computational domain, to simulate the waves over a large spatial scale and provide boundary conditions for SWAN model simulations, implemented on a fine-resolution nested domain for the Yangtze Estuary area. The Takahashi wind model is applied to the simulation of the East China Sea scale （3-hourly） and Yangtze Estuary scale （1-hourly） winds. Simulations of significant wave heights in the East China Sea show that the highest waves are on the right side of the storm track, and maxima tend to occur at the eastern deep-water open boundary of the Yangtze Estuary. In the Yangtze Estuary, incoming swell is dominant over locally generated waves before the typhoon approaches the Estuary. As the typhoon approaches the Estuary, wind waves and swell coexist, and the wave direction is mainly influenced by the swell direction and the complex topography.     

基于海气耦合模型的渤海两种类型风暴潮数值模拟与对比分析

渤海一年四季都易受到由温带风暴和热带气旋所致风暴潮的影响。为了缓解风暴潮灾害对海岸地区人员生命财产的影响,十分有必要了解大型风暴潮的发生过程和机制。目前大部分研究主要局限于单一的温带风暴潮或台风风暴潮。本文利用所构建的海气耦合数值模型研究了发生于渤海的两种类型的风暴潮,对发生在渤海的2次典型强风暴潮过程进行了模拟。由WRF模型模拟得到的风场强度和最低海平面气压与实测数据吻合较好,由ROMS模型模拟得到的风暴潮期间水位变化过程与潮位站观测结果也吻合较好。对两种类型风暴潮期间的风场结钩、海面风应力、海洋表面平均流场以及水位分布进行了分析对比,并将耦合模型结果与非耦合模型结果进行了对比。研究表明,渤海两种类型风暴潮期间的风场结钩、海面风应力、海洋表面平均流场以及水位分布等均存在巨大差异。渤海风暴潮的强度主要由海洋表面的驱动力所决定,但同时也受海岸地形地貌的影响。     

Upwelling in the Alaskan Beaufort Sea: Atmospheric forcing and local versus non-local response

The spin up and relaxation of an autumn upwelling event on the Beaufort slope is investigated using a combination of oceanic and atmospheric data and numerical models. The event occurred in November 2002 and was driven by an Aleutian low storm. The wind field was strongly influenced by the pack-ice distribution, resulting in enhanced winds over the open water of the Chukchi Sea. Flow distortion due to the Brooks mountain range was also evident. Mooring observations east of Barrow Canyon show that the Beaufort shelfbreak jet reversed to the west under strong easterly winds, followed by upwelling of Atlantic Water onto the shelf. After the winds subsided a deep eastward jet of Atlantic Water developed, centered at 250 m depth. An idealized numerical model reproduces these results and suggests that the oceanic response to the local winds is modulated by a propagating signal from the western edge of the storm. The disparity in wave speeds between the sea surface height signal—traveling at the fast barotropic shelf wave speed—versus the interior density signal—traveling at the slow baroclinic wave speed—leads to the deep eastward jet. The broad-scale response to the storm over the Chukchi Sea is investigated using a regional numerical model. The strong gradient in windspeed at the ice edge results in convergence of the offshore Ekman transport, leading to the establishment of an anti-cyclonic gyre in the northern Chukchi Sea. Accordingly, the Chukchi shelfbreak jet accelerates to the east into the wind during the storm, and no upwelling occurs west of Barrow Canyon. Hence the storm response is fundamentally different on the Beaufort slope (upwelling) versus the Chukchi slope (no upwelling). The regional numerical model results are supported by additional mooring data in the Chukchi Sea.     

Effects of winds,tides and storm surges on ocean surface waves in the Sea of Japan

Ocean surface waves are strongly forced by high wind conditions associated with winter storms in the Sea of Japan. They are also modulated by tides and storm surges. The effects of the variability in surface wind forcing, tides and storm surges on the waves are investigated using a wave model, a high-resolution atmospheric mesoscale model and a hydrodynamic ocean circulation model. Five month-long wave model simulations are inducted to examine the sensitivity of ocean waves to various wind forcing fields, tides and storm surges during January 1997. Compared with observed mean wave parameters, results indicate that the high frequency variability in the surface wind filed has very great effect on wave simulation. Tides and storm surges have a significant impact on the waves in nearshores of the Tsushima-kaihyō, but not for other regions in the Sea of Japan. High spatial and temporal resolution and good quality surface wind products will be crucial for the prediction of surface waves in the JES and other marginal seas, especially near the coastal regions.     

基于SWAN模型的南中国海“莫拉菲”台风浪研究

我国的水运工程建设频繁受到台风浪的侵袭。为了对台风浪的防灾减灾提供有益帮助,本文基于第三代海浪模式SWAN建立了南中国海台风浪数值模型,并以“0906”号台风“莫拉菲”为例对模拟结果进行了分析。结果表明,台风风场与波浪场相似,即大小均由中心向外围递减,方向均为逆时针旋转;台风风场呈圆对称分布,而波浪场由于受到海底地形与岸线影响,呈现椭圆对称分布。有效波高等值线亦从中心向外围递减,且形状受地形与岸线影响较大。对台风浪组成机制的探讨结果显示风浪和涌浪均可组成台风浪,且海底地形与岸线(例如岛屿效应)亦对台风浪特性有所影响。     

A synchronously coupled tide–wave–surge model of the Yellow Sea

A coupled wave–tide–surge model has been established in this study in order to investigate the effect of tides, storm surges, and wind waves interactions during a winter monsoon on November 1983 in the Yellow Sea. The coupled model is based on the synchronous dynamic coupling of a third-generation wave model, WAM-Cycle 4, and the two-dimensional tide–surge model. The surface stress generated by interactions between wind and waves is calculated using the WAM-Cycle 4 directly based on an analytical approximation of the results obtained from the quasi-linear theory of wave generation. The changes of bottom friction factor generated by waves and current interactions are calculated by using simplified bottom boundary layer model. The model simulations showed that bottom velocity and effective bottom drag coefficient induced by combination of wave and current were increased in shallow waters of up to 50 m in the Yellow Sea during the wintertime strong storm conditions.