一种港口塔吊水平风荷载预报模型的设计和实现

利用2012-06—2013-05渤海湾北岸曹妃甸港100m风能塔风观测资料,研究了空气动力学粗糙度z0的月变化特征及其和地面10m风速之间的关系,并针对港口安全运营调度精细化气象服务保障需求,设计了一种港口塔吊定点、定量水平风荷载的预报模型。结果表明:受海陆风和周围环境的季节性变化影响,渤海湾北岸z0具有明显的月变化特征;通过拟合确立了z0和地面10m处10min平均风速在海-陆风和陆-海风两个方位上的粗糙度方程,梯度风速计算试验显示方程稳定可用;基于以上结论建立了定点、定量风荷载预报模型,预报试验和程序开发结果表明,基于上述结论所建立的港口塔吊水平风荷载计算模型正确可行,更适用于风险预报业务。     

MEOFIS平台在渤海湾北部海面气温和风速精细化预报中的适用性分析

基于＂动力-统计＂预报方法的MEOFIS（精细化气象要素客观预报）平台以相关模式预报结果为基础,结合历史实况资料建立预报模型,实现站点的精细化预报.利用2009～2011年的T639模式产品和渤海湾北部相关观测站的数据积累统计建模,并对2012～2013年海面4个季节的气温和风速进行预报统计,对比分析该平台在海面气温和风速预报中的适用性.经客观检验,1℃误差范围内,海面各季节的气温和风速预报准确率均高于陆上的预报;海面日最高、日最低和逐3 h气温预报准确率均超过68%,秋季的日最高气温、逐3 h气温和冬季的日最低气温预报最为理想,准确率分别达86.8%、75.2%和78.9%,春季的气温预报整体不理想;显著性检验结果显示：和T639直接输出的结果相比,MEOFIS在各季节的气温预报中具有明显的订正能力.2 m/s误差范围内,过渡性季节春、秋季的日最大风速预报准确率均超过75.0%,夏季的预报效果较差,但逐3 h风速预报准确率最高,达78.0%,冬季的风速预报效果整体不佳;利用总体平均经验模态分解法（EEMD）对各月逐3 h的海面气温和风速预报误差做滤波处理,结果显示MEOFIS平台对这两要素的预报误差均存在明显的双周震荡波,通过滤波可以提高二者预报的准确率,且气温预报准确率的提高更大.预报偏差和方差小的季节,预报准确率的改善更为理想.     

Circulation pattern and current variations with respect to tidal frequency in the sea near the head of Suruga Bay

Current measurements were conducted 10 m below the sea surface near the head of Suruga Bay intermittently from 1970 to 1978. The circulation pattern is usually counterclockwise; northward along the east coast (off Heda and at the mouth of Uchiura Inlet), westward along the north coast (off Fuji), and southwestward along the west coast (off Shimizu). The amplitudes of the four major tidal constituents of current variation, M₂, S₂, K₁ and O₁, are much larger than those expected from sea level variations along the coast. The amplitudes of the diurnal constituents of current variation are much larger than those of the semidiurnal constituents, while the amplitudes of the semidiurnal constituents of sea level variation are much larger than those of the diurnal constituents. The observed amplitude of the predominant diurnal constituents exhibit large seasonal changes and tend to increase with the development of the stratification of the upper part of the water in Suruga Bay. These facts strongly suggest that the observed current variations are mainly associated with internal tides in Suruga Bay.     

南极Dome A至普里兹湾沿岸下降风特征

本文利用我国极地数值天气预报系统和美国南极中尺度预报系统的存档数据,分析了Dome A至普里兹湾沿岸地区下降风风场的时空分布和大气质量通量,给出了该地区下降风的基本特点。该地区下降风受南极冰盖地形影响强烈,艾默里冰架西侧等陡峭地区风速总体较大;下降风随季节变化较大,冬季的下降风较强。强下降风在前进过程中有绝热增温现象,并给艾默里冰架西部带来近表层升温。下降风风速最大处位于地面以上约100～200 m高度,风速较大地区的下降风在垂直方向上分布较为深厚。下降风在普里兹湾沿岸的表层大气质量通量在时空分布上极不均匀,艾默里冰架西侧的下降风气流较强时,普里兹湾海域有较多的中尺度气旋活动。下降风引发普里兹湾中尺度气旋旋生的过程值得关注,需进一步研究下降风引发中尺度气旋的机理。     

基于MTSAT卫星遥感的中国海及西北太平洋海域海表温度日增温研究

Hourly sea surface temperature(SST) observations from the geostationary satellite are increasingly used in studies of the diurnal warming of the surface oceans. The aim of this study is to derive the spatial and temporal distribution of diurnal warming in the China seas and northwestern Pacific Ocean from Multi-functional Transport Satellite(MTSAT) SST. The MTSAT SST is validated against drifting buoy measurements firstly. It shows mean biases is about –0.2°C and standard deviation is about 0.6°C comparable to other satellite SST accuracy. The results show that the tropics, mid-latitudes controlled by subtropical high and marginal seas are frequently affected by large diurnal warming. The Kuroshio and its extension regions are smaller compared with the surrounding regions. A clear seasonal signal, peaking at spring and summer can be seen from the long time series of diurnal warming in the domain in average. It may due to large insolation and low wind speed in spring and summer, while the winter being the opposite. Surface wind speed modulates the amplitude of the diurnal cycle by influencing the surface heat flux and by determining the momentum flux. For the shallow marginal seas, such as the East China Sea, turbidity would be another important factor promoting diurnal warming. It suggests the need for the diurnal variation to be considered in SST measurement, air-sea flux estimation and multiple sensors SST blending.     

Numerical Simulation of Extreme Sea Levels Using Location Specific High Resolution Model for Gujarat Coast of India

Although the frequency of tropical cyclones is less in the Arabian sea compared to that of the Bay of Bengal, there are several severe tropical cyclones which caused extensive damage along the Gujarat coast. In view of the high tidal range in the funnel-shaped gulfs of the Khambhat and the Kachch, it is very useful to study the surge response in these regions. There is always a possibility of abnormal rise of sea level when the occurrence of surge coincides with high tide, which may eventually cause inundation of vast stretches of shallow coastal areas. In view of this, a location specific fine resolution model is developed for the Gujarat coast. The east-west and north-south grid distances for the model are 5.1 km and 5.2 km, respectively. Several numerical experiments are carried out to compute the extreme sea levels using the wind stress forcings representative of 1982, 1996, and 1998 cyclones, which crossed this region. The model-computed extreme sea levels are in good agreement with the available observations.     

Numerical Simulation of Extreme Sea Levels Using Location Specific High Resolution Model for Gujarat Coast of India

Although the frequency of tropical cyclones is less in the Arabian sea compared to that of the Bay of Bengal, there are several severe tropical cyclones which caused extensive damage along the Gujarat coast. In view of the high tidal range in the funnel-shaped gulfs of the Khambhat and the Kachch, it is very useful to study the surge response in these regions. There is always a possibility of abnormal rise of sea level when the occurrence of surge coincides with high tide, which may eventually cause inundation of vast stretches of shallow coastal areas. In view of this, a location specific fine resolution model is developed for the Gujarat coast. The east-west and north-south grid distances for the model are 5.1 km and 5.2 km, respectively. Several numerical experiments are carried out to compute the extreme sea levels using the wind stress forcings representative of 1982, 1996, and 1998 cyclones, which crossed this region. The model-computed extreme sea levels are in good agreement with the available observations.     

渤、黄、东海8个主要分潮的数值模拟研究

应用MIKE数值模拟软件,采用无结构三角形网格,建立一套计算区域包括整个渤海、黄海、东海以及东海大陆架和琉球群岛的高分辨率数值模型,考虑了实际水深和岸线,外海开边界采用西北太平洋大模型结果的潮位提供,模拟了东中国海潮波的波动过程,对潮波垂直运动过程进行调和分析,得到了渤海、黄海、东海的M2,S2,K1,O1以及N2,K2,P1,Q1八个主要分潮的传播和分布特征。利用中国沿海14个潮位站的调和常数对模型结果进行了验证,验证结果显示模型较为准确可靠。研究结果表明:4个主要半日潮(全日潮)在渤、黄、东海的传播情形基本相似,即潮波在渤海、黄海、东海沿岸的传播性质上类似沿岸开尔文波的传播形态,并且成功再现了计算海域的4个半日分潮无潮点和2个全日分潮无潮点。全日潮振幅各无潮点附近振幅最小,而海湾的波腹区振幅最大,东海潮差呈现近岸方向振幅大、离岸方向振幅小,浙闽沿海振幅也较大,黄海振幅相对较小,渤海振幅在辽东湾和渤海湾顶最大,两个无潮点周边振幅较小。     

Continental shelf waves off the Fukushima coast

Numerical experiments are performed on shelf waves forced by wind stress with a spectral peak around a period of 100 hr. Water depth in the numerical model is a function of offshore distance only and resembles a bathymetric profile off the Fukushima coast. A pair of vortices alined in the offshore direction and a large vortex are reproduced and they propagate southward outside the forced region. Judging from the propagation speed, the former corresponds to the second-mode and the latter to the first-mode shelf waves. In the forced region, the propagation speed of a trough and a ridge is slow, 3–5km hr^–1. These propagation characteristics reproduce those observed along the Fukushima coast and this propagation speed corresponds to that of second-and third-mode shelf waves. Thus, it is concluded that the periodical current fluctuations observed in the inshore region along the Fukushima coast are due to motions associated with the second-and third-mode shelf waves.     

Fine structure of a Greenland reverse tip jet: a numerical simulation

Reverse tip jets are strong low-level winds with easterly component that form near the southern tip of Greenland. In the present study, a reverse tip jet case which occurred from 21 to 22 December 2000 was examined to clarify its fine structure using a numerical model with a horizontal resolution of 3 km. The reverse tip jet, showing the supergeostrophic wind speed with a maximum wind speed in excess of 45 m s⁻¹, extended from the east coast of Greenland to the west of Cape Farewell with anticyclonic curvature. A cloud free region coincided with the jet indicated that there was a mesoscale downdraft. Along the eastern edge of the jet, a banded cloud formed between the upstream easterly wind and the colder northerly wind that is a part of the jet and is located along the east coast. This cloud was associated with large gradients in surface wind speed, temperature, moisture, and heat flux. A maximum surface total heat flux of 300 W m⁻² coincided with the location of the jet. It is suggested that the orographic deflection by Greenland's large-scale topography as well as small-scale downslope winds behind mountains with fiords causes the reverse tip jet.     

Simulation of storm surge,wave, and coastal inundation in the Northeastern Gulf of Mexico region during Hurricane Ivan in 2004

Hurricane-induced storm surge, waves, and coastal inundation in the northeastern Gulf of Mexico region during Hurricane Ivan in 2004 are simulated using a fine grid coastal surge model CH3D (Curvilinear-grid Hydrodynamics in 3D) coupled to a coastal wave model SWAN, with open boundary conditions provided by a basin-scale surge model ADCIRC (Advanced CIRCulation) and a basin-scale wave model WW3 (WaveWatch-III). The H1wind, a reanalysis 10-m wind produced by the NOAA/AOML Hurricane Research Division (HRD), and a relatively simple analytical wind model are used, incorporating the effect of land dissipation on hurricane wind. Detailed comparison shows good agreement between the simulated and measured wind, waves, surge, and high water marks. Coastal storm surge along the coast is around 2–3 m, while peak surge on the order of 3.5 m is found near Pensacola, which is slightly to the east of the landfall location on Dauphin Island. Wind waves reach 20 m at the Mobile South station (National Data Buoy Center buoy 42040) on the shelf and 2 m inside the Pensacola/Escambia Bay. Model results show that wave-induced surge (total surge subtracted by the meteorologically-induced surge due to wind and pressure) accounts for 20–30% of the peak surge, while errors of the simulated surge and waves are generally within 10% of measured data. The extent of the simulated inundation region is increased when the effects of waves are included. Surge elevations simulated by the 3D model are generally up to 15% higher than that by the 2D model, and the effects of waves are more pronounced in the 3D results. The 3D model results inside the Pensacola/Escambia Bay show significant vertical variation in the horizontal currents. While the estuary has little impact on the surge elevation along the open coastal water, surge at the head of Escambia Bay is more than 50% higher than that at the open coast with 1.5 h delay.     

Eddies along front of warm winter current off the north coast of Spain and at Jovellanos Seamount

I~IOXSatellite infrared measurements are now accepted as an effeCtive way of mapping sea surfacetemperature (SST) distributions on global and regional scales. While regional SST maps are widely uest as background data for oceanographic experiments, they tend to be considered by oceanographers as at best qualitative tools. There is SCOPe for developing the use of satellite SST imagesac extensively for the study of mesoscale d~ical processes, as this paper seeks to demonstrate. As Part O…     

大亚湾冬季水位的亚潮变化及其与南海的耦合

本文应用常规时间序列谱分析方法和频域的多输入线性模型研究了冬季广东省大亚湾内水位的亚潮变化及其与大亚湾本地和外海远处各种强迫作用因素间的关系。结果表明：冬季在亚湾亚潮水位的能量主要集中在６．４ｄ和３．６ｄ频带,而在１０．７ｄ频带还有一较弱谱峰,同期广东沿海风的低频能量也主要集中于２－７ｄ频段。造成冬季亚潮水位变化的原因包含了大亚湾本地气象条件的影响,但主要是远地因素作用于大亚湾的结果。外海影响一方     

Long-range sonar views of submarine canyons

Submarine canyons on the northern margin of the Bay of Biscay have been viewed with side-scan sonar at slant ranges carying from 1 km to 22 km. First results indicate the importance of secondary gullying, and that while published charts may show the correct number of canyons the trends are sometimes more oblique to the regional slope than shown (probably fault-controlled). In general the similarity to subaerial fluvial drainage patterns is striking.     

Case study of wind jet transition and localized responses of wind wave along the pacific coast of Northern Japan by synergetic use of satellite and in situ observations

We present a case study of low-level wind jets induced in sequence by orographic effects off the Pacific coast of northern Japan during 7–11 June 2003, and demonstrate that the transition of the wind jets causes areal differences of wave height variations along the coast. First, we describe evolution and structure of the wind jet by analyzing SeaWinds scatterometer wind measurements. Under the easterly wind, a strong wind jet formed after passing by Cape Erimo. As the wind shifted to the southeast, the wind jet started to decay. In turn, the southerly wind along the coast led to another wind jet in the lee of the easternmost tip of the Sanriku coast. We then identify onsets and decays of the wind jets from time series of wind speed at meteorological stations. Finally, we demonstrate that the transition of the wind jets has local impacts on wave height variations. Significant wave heights measured by altimeters were correlated positively with local wind energy, i.e., squares of wind speeds. Accompanying the wind jet formation/decline, significant differences of wave height variations became marked among wave observation stations located along the coast at intervals of up to 50 km.     

Effect of Salinity and Currents on Sea Level Variation Along the Indian Coast: A Numerical Study

The process of upwelling/sinking and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. Further,precipitation and monsoonal floods, apart from the marine meteorological parameters, are expected to influence the sea level fluctuations along the coast. This study comprises determining the sea level from the various parameters together with the pure wind stress forcing, which is compared with the observed cycle. However, it is found that there is considerable difference between the computations and observations. This suggests that the sea level is dependent not just on the local forcing alone, but also on the induced background circulation as well. For example, the sea level changes along the east coast of India, particularly the northern region, are more sensitive to freshwater discharge from various rivers joining the Bay of Bengal. This is due to more frequently occurring pre- and postmonsoon cyclonic storms and the associated surges in the Bay of Bengal as compared to the Arabian Sea. Hence the salinity effects are particularly important in the coastal waters off the east coast of India during monsoon months (June-September). For the west coast of India, however, it is expected that the large-scale coastal circulation may play a role in determining sea level changes in addition to other forcings. The salinity effects are negligible along the west coast in the absence of any major river systems that join the Arabian Sea. The local advection currents caused by the offshore directed freshwater discharge from various estuaries joining the coastal bay also seemed to influence the sea level. In order to elucidate the essential dynamics involved and to study the effect of the remote forcing, a three-dimensional baroclinic, nonlinear numerical model is used with appropriate open boundary conditions. The local effect of the current has been incorporated in the west coast model by means of opening a channel at Cochin through which the rainwater is carried away to the model ocean. The low saline plume, cascading from north along the east cost of India, has been incorporated in the east coast model through a proper forcing applied at the northern boundary of the model. With the inclusion of these remote forcings in the models, the disagreement between the simulations and the observations is minimized.     

Effect of Salinity and Currents on Sea Level Variation Along the Indian Coast: A Numerical Study

The process of upwelling/sinking and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. Further,precipitation and monsoonal floods, apart from the marine meteorological parameters, are expected to influence the sea level fluctuations along the coast. This study comprises determining the sea level from the various parameters together with the pure wind stress forcing, which is compared with the observed cycle. However, it is found that there is considerable difference between the computations and observations. This suggests that the sea level is dependent not just on the local forcing alone, but also on the induced background circulation as well. For example, the sea level changes along the east coast of India, particularly the northern region, are more sensitive to freshwater discharge from various rivers joining the Bay of Bengal. This is due to more frequently occurring pre- and postmonsoon cyclonic storms and the associated surges in the Bay of Bengal as compared to the Arabian Sea. Hence the salinity effects are particularly important in the coastal waters off the east coast of India during monsoon months (June-September). For the west coast of India, however, it is expected that the large-scale coastal circulation may play a role in determining sea level changes in addition to other forcings. The salinity effects are negligible along the west coast in the absence of any major river systems that join the Arabian Sea. The local advection currents caused by the offshore directed freshwater discharge from various estuaries joining the coastal bay also seemed to influence the sea level. In order to elucidate the essential dynamics involved and to study the effect of the remote forcing, a three-dimensional baroclinic, nonlinear numerical model is used with appropriate open boundary conditions. The local effect of the current has been incorporated in the west coast model by means of opening a channel at Cochin through which the rainwater is carried away to the model ocean. The low saline plume, cascading from north along the east cost of India, has been incorporated in the east coast model through a proper forcing applied at the northern boundary of the model. With the inclusion of these remote forcings in the models, the disagreement between the simulations and the observations is minimized.     

Pb,Zn, Cs,Sc and rare earth elements as tracers of the Loire and Gironde particles on the Biscay shelf (SW France)

The western Atlantic continental margin of the Bay of Biscay is characterised by a combined macro-tidal and a high energy environment. These conditions are responsible for the essentially sandy sedimentary cover along with well-defined fine deposit zones observed on the shelf. The main continental sources are the Loire, Gironde and Adour Rivers. It is estimated that 2.4 to 2.5 million tons of fine sediments are supplied annually to the ocean from these rivers of the French Atlantic coast. The Gironde and the Loire contribute with 84 % and the Gironde with 60 % of this amount. Previous studies of the distribution of the clay mineral assemblages and of oligo-elements have distinguished two provinces (north and south Biscay areas) according to these riverine sources. The use of an inductively coupled plasma-mass spectrometry (ICP-MS) technique allowed us to analyse both heavy metals and rare earth elements (REE), thus permitting an effective characterisation of continental sources. On the basis of these results, it has been possible to better identify the respective contributions of the Loire and the Gironde Rivers to the fine-grained sedimentation on the inner shelf.     

Regional scenarios of sea level rise and impacts on Basque (Bay of Biscay) coastal habitats,throughout the 21st century

Global climate models have predicted a rise on mean sea level of between 0.18 m and 0.59 m by the end of the 21st Century, with high regional variability. The objectives of this study are to estimate sea level changes in the Bay of Biscay during this century, and to assess the impacts of any change on Basque coastal habitats and infrastructures. Hence, ocean temperature projections for three climate scenarios, provided by several atmosphere–ocean coupled general climate models, have been extracted for the Bay of Biscay; these are used to estimate thermosteric sea level variations. The results show that, from 2001 to 2099, sea level within the Bay of Biscay will increase by between 28.5 and 48.7 cm, as a result of regional thermal expansion and global ice-melting, under scenarios A1B and A2 of the Intergovernmental Panel on Climate Change. A high-resolution digital terrain model, extracted from LiDAR, data was used to evaluate the potential impact of the estimated sea level rise to 9 coastal and estuarine habitats: sandy beaches and muds, vegetated dunes, shingle beaches, sea cliffs and supralittoral rock, wetlands and saltmarshes, terrestrial habitats, artificial land, piers, and water surfaces. The projected sea level rise of 48.7 cm was added to the high tide level of the coast studied, to generate a flood risk map of the coastal and estuarine areas. The results indicate that 110.8 ha of the supralittoral area will be affected by the end of the 21st Century; these are concentrated within the estuaries, with terrestrial and artificial habitats being the most affected. Sandy beaches are expected to undergo mean shoreline retreats of between 25% and 40%, of their width. The risk assessment of the areas and habitats that will be affected, as a consequence of the sea level rise, is potentially useful for local management to adopt adaptation measures to global climate change.