共查询到20条相似文献，搜索用时 46 毫秒
1.
By taking into consideration the effects of ocean surface wave-induced Stokes drift velocity U,w and current velocityU,c on the drag coefficient,the spatial distributions of drag coefficient and wind stress in 2004 are computed over the tropical andnorthern Pacific using an empirical drag coefficient parameterization formula based on wave steepness and wind speed.The globalocean current field is generated from the Hybrid Coordinate Ocean Model (HYCOM) and the wave data are generated from Wave-watch Ⅲ (WW3).The spatial variability of the drag coefficient and wind stress is analyzed.Preliminary results indicate that theocean surface Stokes drift velocity and current velocity exert an important influence on the wind stress.The results also show thatconsideration of the effects of the ocean surface Stokes drift velocity and current velocity on the wind stress can significantly im-prove the modeling of ocean circulation and air-sea interaction processes. 相似文献
2.
We investigated the Stokes drift-driven ocean currents and Stokes drift-induced wind energy input into the upper ocean using a two-way coupled wave-current modeling system that consists of the Princeton Ocean Model generalized coordinate system (POMgcs), Simulating WAves Nearshore (SWAN) wave model, and the Model Coupling Toolkit (MCT). The Coriolis-Stokes forcing (CSF) computed using the wave parameters from SWAN was incorporated with the momentum equation of POMgcs as the core coupling process. Experimental results in an idealized setting show that under the steady state, the scale of the speed of CSF-driven current was 0.001 m/s and the maximum reached 0.02 m/s. The Stokes drift-induced energy rate input into the model ocean was estimated to be 28.5 GW, taking 14% of the direct wind energy rate input. Considering the Stokes drift effects, the total mechanical energy rate input was increased by approximately 14%, which highlights the importance of CSF in modulating the upper ocean circulation. The actual run conducted in Taiwan Adjacent Sea (TAS) shows that: 1) CSF-based wave-current coupling has an impact on ocean surface currents, which is related to the activities of monsoon winds; 2) wave-current coupling plays a significant role in a place where strong eddies present and tends to intensify the eddy’s vorticity; 3) wave-current coupling affects the volume transport of the Taiwan Strait (TS) throughflow in a nontrivial degree, 3.75% on average. 相似文献
3.
The wave-forcing ’Coriolis-Stokes forcing’ and ’Stokes-vortex force’ induced by Stokes drift affect the upper ocean jointly.To study the effect of the wave-induced Stokes drift on the dynamics of the ocean mixed layer,a new three-dimensional(3D) numerical model is derived using the primitive basic equations and Eulerian wave averaging.The Princeton Ocean Model(POM),a 3D primitive equation ocean model is used with the upper wave-averaged basic equations.The global ocean circulation is simulated using the POM model,and the Stokes drift is evaluated based on the wave data generated by WAVEWATCH III.We compared simulations with and without the Stokes drift.The results show that the magnitude of the Stokes drift is comparable with the Eulerian mean current.Including the Stokes drift in the ocean model affects both the Eulerian current and the Lagranian drift and causes the vertical mixing coefficients to increase. 相似文献
4.
Whitecapping plays an important role in many air-sea exchange and upper ocean processes. Traditionally, whitecap coverage
is parameterized as a function of wind speed only. At present, the relative speed of ocean current to wind is considered to
be important in the air-sea exchange parameterization which is the function of wind speed only. In this paper, the effects
of ocean surface velocity (current velocity and wave induced velocity) and the wave parameters on whitecap coverage through
relative speeds are investigated, by applying a 2-parameter whitecap coverage model to the Atlantic Ocean. It is found that
the impacts of both current and wave on whitecap coverage are considerable in the most part of the Atlantic Ocean. It is interesting
that the effect of wave is more significant than that of current. 相似文献
5.
The inflow angle of tropical cyclones(TC) is generally neglected in numerical studies of ocean surface waves induced by TC.In this study,the impacts of TC inflow angle on ocean surface waves were investigated using a high-resolution wave model.Six numerical experiments were conducted to examine,in detail,the effects of inflow angle on mean wave parameters and the spectrum of wave directions.A comparison of the waves simulated in these experiments shows that inflow angle significantly modifies TC-induced ocean surface waves.As the inflow angle increases,the asymmetric axis of the significant wave height(SWH) field shifts 30u clockwise,and the maximum SWH moves from the front-right to the rear-right quadrant.Inflow angle also affects other mean wave parameters,especially in the rear-left quadrant,such as the mean wave direction,the mean wavelength,and the peak direction.Inflow angle is a key factor in wave models for the reproduction of double-peak or multi-peak patterns in the spectrum of wave directions.Sensitivity experiments also show that the simulation with a 40u inflow angle is the closest to that of the NOAA statistical SLOSH inflow angle.This suggests that 40u can be used as the inflow angle in future TC-induced ocean surface wave simulations when SLOSH or observed inflow angles are not available. 相似文献
6.
The effects of the mixing of wave transport flux residual(Bvl) on the upper ocean is studied through carrying out the control run(CR) and a series of sensitive runs(SR) with ROMS model.In this study,the important role of Bvl is revealed by comparing the ocean temperature,statistical analysis of errors and evaluating the mixed layer depth.It is shown that the overestimated SST is improved effectively when the wave-induced mixing is incorporated to the vertical mixing scheme.As can be seen from the vertical structure of temperature 28℃ isotherm changes from 20 min CR to 35 m in SR3,which is more close to the observation.Statistic analysis shows that the root-mean-square errors of the temperature in 10 m are reduced and the correlation between model results and observation data are increased after considering the effect of Bvl.The numerical results of the ocean temperature show improvement in summer and in tropical zones in winter,especially in the strong current regions in summer.In August the mixed layer depth(MLD) which is defined as the depth that the temperature has changed 0.5℃ from the reference depth of 10 m is further analyzed.The simulation results have a close relationship with undetermined coefficient of Bvl,sensitivity studies show that a coefficient about 0.1 is reasonable value in the model. 相似文献
7.
Parameterized first-guess spectrum method for retrieving directional spectrum of swell-dominated waves and huge waves from SAR images 总被引：3，自引：0，他引：3
A method to retrieve ocean wave spectra from SAR images, named Parameterized First-guess Spectrum Method (PFSM), was proposed after interpretation of the theory to ocean wave imaging and analysis of the drawbacks of the retrieving model generally used. In this method, with additional information and satellite parameters, the separating wave-number is first calculated to determine the maximum wave-number beyond which the linear relation can be used. The separating wave-number can be calculated using the additional information on wind velocity and parameters of SAR satellite. And then the SAR spectrum can be divided into SAR spectrum of wind wave and of swell according to the result of separating wave-number. The portion of SAR spectrum generated by wind wave, is used to search for the most suitable parameters of ocean wind wave spectrum, including propagation direction of ocean wave, phase speed of dominating wave and the angle spreading coefficient. The swell spectrum is acquired by directly inversing the linear relation of ocean wave spectrum to SAR spectrum given the portion of SAR spectrum generated by swell. We used the proposed method to retrieve the ocean wave spectrum from ERS-SAR data from the South China Sea and compared the result with altimeter data. The agreement indicates that the PFSM is reliable. 相似文献
8.
This study investigates the contribution of mesoscale eddies to the subduction and transport of North Pacific Eastern Subtropical Mode Water(ESTMW)using the high-frequency output of an eddy-resolved ocean model spanning the period 1994–2010.Results show that the subduction induced by mesoscale eddies accounts for about 31%of the total subduction of ESTMW formation.The volume of ESTMW trapped by anticyclonic eddies is slightly larger than that trapped by cyclonic eddies.The ESTMW trapped by all eddies in May reaches up to about 2.8×1013m3,which is approximately 16%of the total ESTMW volume.The eddy-trapped ESTMW moves primarily westward,with its meridional integration at 18°–30°N reaching about 0.17Sv,which is approximately 18%of the total zonal ESTMW transport in this direction,at 140°W.This study highlights the important role of eddies in carrying ESTMW westward over the northeastern Pacific Ocean. 相似文献
9.
The propagation of long-waves, such as tidal waves from the coastal oceam into shallow estuarine waters,often produces asymmetries of veolcity and water level in time series resulting in long-wave breaking.Tian (1994) studied the mechanism of long-wave breaking in an infinite channel with constant depth,considering nth power bottom friction. This study is for the case of a half infinite channel with bottomslope, taking linear bottom friction into account. The wave breaking time and wave breaking location areestimated and the criteria for long-wave breaking in this particular case are obtained. The results obtainedcan also be e asily applied to the case considering wind stress. 相似文献
10.
The propagation of long-waves, such as tidal waves from the coastal ocean into shallow estuarine waters, often produces asymmetries
of velocity and water level in time series resulting in long-wave breaking. Tian (1994) studied the mechanism of long-wave
breaking in an infinite channel with constant depth, consideringnth power bottom friction. This study is for the case of a half infinite channel with bottom slope, taking linear bottom friction
into account. The wave breaking time and wave breaking location are estimated and the criteria for long-wave breaking in this
particular case are obtained. The results obtained can also be easily applied to the case considering wind stress. 相似文献
11.
《中国海洋湖沼学报》2019,(6)
The transport flux residue of surface waves plays an important role in a variety of ocean phenomena, for example, the change in sea surface temperature(SST) and upper mixed layer profile that were studied in a series of recent papers. In the previous studies, its effect was discussed rigorously and fragmented based on numerical modeling. Here we propose a relatively comprehensive and simplified exposition of the wave transport flux residue, and focus on its influence under typhoon conditions with strong background current. An analogue Reynolds Number is presented for tentative comparison with wave-generated turbulence mixing, especially in the coastal area. Numerical results indicate that both overwhelming dynamical mixing processes can remarkably change the coastal environment, and should not be ignored consciously for further marine hazards assessment. 相似文献
12.
1 Introduction TheMadden JulianOscillation (MJO)isastrongatmosphericconvection phenomenonoccurringovertheEasternIndianOceanandtheTropicalWesternPacific,usuallyinregionswithseasurfacetempera tures (SSTs)over 2 9℃ .Theeastwardmovingofalarge scalecirculat… 相似文献
13.
Because of the intrinsic difficulty in determining distributions for wave periods, previous studies on wave period distribution
models have not taken nonlinearity into account and have not performed well in terms of describing and statistically analyzing
the probability density distribution of ocean waves. In this study, a statistical model of random waves is developed using
Stokes wave theory of water wave dynamics. In addition, a new nonlinear probability distribution function for the wave period
is presented with the parameters of spectral density width and nonlinear wave steepness, which is more reasonable as a physical
mechanism. The magnitude of wave steepness determines the intensity of the nonlinear effect, while the spectral width only
changes the energy distribution. The wave steepness is found to be an important parameter in terms of not only dynamics but
also statistics. The value of wave steepness reflects the degree that the wave period distribution skews from the Cauchy distribution,
and it also describes the variation in the distribution function, which resembles that of the wave surface elevation distribution
and wave height distribution. We found that the distribution curves skew leftward and upward as the wave steepness increases.
The wave period observations for the SZFII-1 buoy, made off the coast of Weihai (37°27.6′ N, 122°15.1′ E), China, are used
to verify the new distribution. The coefficient of the correlation between the new distribution and the buoy data at different
spectral widths (ν=0.3−0.5) is within the range of 0.968 6 to 0.991 7. In addition, the Longuet-Higgins (1975) and Sun (1988)
distributions and the new distribution presented in this work are compared. The validations and comparisons indicate that
the new nonlinear probability density distribution fits the buoy measurements better than the Longuet-Higgins and Sun distributions
do. We believe that adoption of the new wave period distribution would improve traditional statistical wave theory. 相似文献
14.
SHI Hongyuan CAO Xuefeng LI Qingjie LI Delei SUN Jiacheng YOU Zaijin SUN Qingying 《中国海洋大学学报(英文版)》2021,(1)
Wave parameters, such as wave height and wave period, are important for human activities, such as navigation, ocean engineering and sediment transport, etc. In this study, wave data from six buoys around Chinese waters, are used to assess the quality of wave height and wave period in the ERA5 reanalysis of the European Centre for Medium-Range Weather Forecasts. Annual hourly data with temporal resolution are used. The difference between the significant wave height(SWH) of ERA 5 and that of the buoy varies from-0.35 m to 0.30 m for the three shallow locations;for the three deep locations, the variation ranges from-0.09 m to 0.09 m. The ERA5 SWH data show positive biases, indicating an overall overestimation for all locations, except for E2 and S1 where underestimation is observed. During the tropical cyclone period, a large(about 32%) underestimation of the maximum SWH in the ERA5 data is observed. Hence, the ERA5 SWH data cannot be used for design applications without site-specific validation. The difference between the annual wave period from ERA5 and the mean wave period from the buoys varies from-1.31 s to 0.4 s. Inter-comparisons suggest that the ERA5 dataset is consistent with the annual mean SWH. However, for the average period, the performance is not good, and half of the correlation coefficients in the four points are less 50%. Overall, the deep water area simulation effect is better than that in the shallow water. 相似文献
15.
Lunyu Wu Changsheng Chen Peifang Guo Maochong Shi Jianhua Qi Jianzhong Ge 《中国海洋大学学报(英文版)》2011,10(1):1-8
An effort was made to couple FVCOM (a three-dimensional (3D),unstructured grid,Finite Volume Coastal Ocean Model) and FVCOM-SWAVE (an unstructured grid,finite-volume surface wave model) for the study of nearshore ocean processes such as tides,circulation,storm surge,waves,sediment transport,and morphological evolution.The coupling between FVCOM and FVCOM-SWAVE was achieved through incorporating 3D radiation stress,wave-current-sediment-related bottom boundary layer,sea surface stress parameterizations,and morphology process.FVCOM also includes a 3D sediment transport module.With accurate fitting of irregular coastlines,the model provides a unique tool to study sediment dynamics in coastal ocean,estuaries,and wetlands where local geometries are characterized by inlets,islands,and intertidal marsh zones.The model was validated by two standard benchmark tests: 1) spectral waves approaching a mild sloping beach and 2) morphological changes of seabed in an idealized tidal inlet.In Test 1,model results were compared with both analytical solutions and laboratory experiments.A further comparison was also made with the structured grid Regional Ocean Model System (ROMS),which provides an insight into the performance of the two models with the same open boundary forcing. 相似文献
16.
四川"9.3"大暴雨中的水汽输送分析 总被引：4，自引：0，他引：4
利用NCEP／NCAR再分析资料对四川“9．3”大暴雨中水汽来源进行了讨论。结果表明,这次暴雨的水汽主要来源于南海、西太平洋地区;异常水汽输送在这次暴雨中占了较大的比例。暴雨日及前3天的异常水汽输送表明,造成此次川东暴雨的异常水汽来源于西太平洋经南海、东海、黄海的向北水汽输送和暴雨区北方的向南水汽输送,以及青藏高原的异常偏西风输送,孟加拉湾的水汽输送对异常强降水并没有明显的作用。大暴雨发生的前期,副高突然异常加强西伸。 相似文献
17.
The validation and assessment of Envisat advanced synthetic aperture radar (ASAR) ocean wave spectra products are important to their application in ocean wave numerical predictions. Six-year ASAR wave spectra data are compared with one-dimensional (1D) wave spectra of 55 co-located moored buoy observations in the northern Pacific Ocean. The ASAR wave spectra data are firstly quality control filtered and spatio-temporal matched with buoy data. The comparisons are then performed in terms of 1D wave spectra, significant wave height (SWH) and mean wave period (MWP) in different spatio-temporal offsets respectively. SWH comparison results show the evident dependence of SWH biases on wind speed and the ASAR SWH saturation effect. The ASAR wave spectra tend to underestimate SWH at high wind speeds and overestimate SWH at low wind speeds. MWP comparison results show that MWP has a systematic bias and therefore it should be bias-modified before used. The comparisons of 1D wave spectra show that both wave spectra agree better at low frequencies than at high frequencies, which indicates the ASAR data cannot resolve the high frequency waves. 相似文献
18.
Absolute geostrophic currents in the North Pacific Ocean are calculated using the P-vector method and gridded Argo profiling data from January 2004 to December 2012. Three-dimensional structures and seasonal variability of meridional heat transport (MHT) and meridional salt transport (MST) are analyzed. The results show that geostrophic and Ekman components are generally opposite in sign, with the southward geostrophic component dominating in the subtropics and the northward Ekman component dominating in the tropics. In combination with the net surface heat flux and the MST through the Bering Strait, the MHT and MST of the western boundary currents (WBCs) are estimated for the first time. The results suggest that the WBCs are of great importance in maintaining the heat and salt balance of the North Pacific. The total interior MHT and MST in the tropics show nearly the same seasonal variability as that of the Ekman components, consistent with the variability of zonal wind stress. The geostrophic MHT in the tropics is mainly concentrated in the upper layers, while MST with large amplitude and annual variation can extend much deeper. This suggests that shallow processes dominate MHT in the North Pacific, while MST can be affected by deep ocean circulation. In the extratropical ocean, both MHT and MST are weak. However, there is relatively large and irregular seasonal variability of geostrophic MST, suggesting the importance of the geostrophic circulation in the MST of that area. 相似文献
19.
《中国海洋大学学报(英文版)》2015,(5)
The beach studied in this paper spans a length of 51 km and is one of several long sandy beaches in the southern Bohai Strait. Due to the obstruction of islands in the northeast and the influence of the underwater topography, the wave environment in the offshore area is complex; beach types and sediment transport characteristics vary along different coasts. The coastlines extracted from six aerial photographs in different years were compared to demonstrate the evolving features. Seven typical beach profiles were selected to study the lateral beach variation characteristics. Continuous wind and wave observation data from Beihuangcheng ocean station during 2009 were employed for the hindcast of the local wave environment using a regional spectral wave model. Then the results of the wave hindcast were incorporated into the LITDRIFT model to compute the sediment transport rates and directions along the coasts and analyze the longshore sand movement. The results show that the coastline evolution of sand beaches in the southern Bohai Strait has spatial and temporal variations and the coast can be divided into four typical regions. Region(I), the north coast of Qimudao, is a slightly eroded and dissipative beach with a large sediment transport rate; Region(II), the southwest coast of Gangluan Port, is a slightly deposited and dissipative beach with moderate sediment transport rate; Region(III), in the central area, is a beach that is gradually transformed from a slightly eroded dissipative beach to a moderately or slightly strong eroded bar-trough beach from west to east with a relatively moderate sediment transport rate. Region(IV), on the east coast, is a strongly eroded and reflective beach with a weak sediment transport rate. The wave conditions exhibit an increasing trend from west to east in the offshore area. The distribution of the wave-induced current inside the wave breaking region and the littoral sediment transport in the nearshore region exhibit a gradual weakening tendency from west to east, which is opposite to the trend of the wave conditions outside the breaking region. The presence of submerged shoal(Dengzhou Shoal), deep trough(Dengzhou Channel), islands and irregular topography influnces the wave climate, beach types, wave-induced current features, littoral sediment transport trends and coastline evolution patterns in the southern Bohai Strait. Human activities, such as the sand exploitation of Dengzhou Shoal and other coastal engineering projects, also influence the beach morphology and coastline evolution. 相似文献
20.
The influence of high-frequency atmospheric forcing on the formation of a well-mixed summer warm water column in the central Bohai Sea is investigated comparing model simulations driven by daily surface forcing and those using monthly forcing data. In the absence of high-frequency atmospheric forcing, numerical simulations have repeatedly failed to reproduce this vertically uniform column of warm water measured over the past 35 years. However, high-frequency surface forcing is found to strongly influence the structure and distribution of the well-mixed warm water column, and simulations are in good agreement with observations. Results show that high frequency forcing enhances vertical mixing over the central bank, intensifies downward heat transport, and homogenizes the water column to form the Bohai central warm column. Evidence presented shows that high frequency forcing plays a dominant role in the formation of the well-mixed warm water column in summer, even without the effects of tidal and surface wave mixing. The present study thus provides a practical and rational way of further improving the performance of oceanic simulations in the Bohai Sea and can be used to adjust parameterization schemes of ocean models. 相似文献