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1.
《大气与海洋》2013,51(3):184-203
Abstract Three widely used wave models, namely, the open ocean wave model (Cycle‐4.5, hereinafter referred to as WAM4.5) and the coastal models, Simulation of WAves Nearshore (Cycle III version 40.31, hereinafter referred to as SWAN) and the K‐model, are applied to Lake Erie to simulate waves at a spatial resolution of about 4 km. The results of a three‐week hindcast study are compared with buoy observations in terms of integrated parameters, one‐dimensional (1‐D) and two‐dimensional (2‐D) energy spectra, scatter plots and statistical analyses of the wave fields. The time development of the 1‐D spectra by the models matches the buoy measurements well. All the wave models tend to overpredict the wave heights and underpredict (particularly the K‐model) the peak period. SWAN performs best for the wave heights and WAM4.5 for the peak periods and is computationally less demanding, whereas the spatial resolution applied to Lake Erie seems to be too coarse for an adequate use of the K‐model. In general, WAM4.5 has advantages over coastal wave models in operational intermediate‐scale applications. 相似文献
2.
Takvor H. Soukissian Aristides M. Prospathopoulos Chrysoula Diamanti 《Journal of Atmospheric & Ocean Science》2002,8(2):163-189
In this paper, a statistical analysis on wind and wave buoy measurements and wind and wave model forecasts obtained during a two-year period (1999-2001) is presented with reference to four characteristic near-shore sites of the Aegean Sea. The measurements are a main product of the "POSEIDON" system aiming at the monitoring and forecasting of the state of the Greek seas, operated by the National Centre for Marine Research (NCMR). Although the two-year period is rather short for a thorough analysis of the local wind and wave climate, yet the obtained results, presented herein for the first time, reveal some interesting features of the corresponding wave and wind characteristics. Comparisons between the measurements and the forecast results are also performed at the locations under consideration. It is found that (i) wind speeds obtained from the POSEIDON weather forecasting system are, in general, in agreement with the measurements, except for high wind speeds which are systematically underestimated, (ii) the WAM model can successfully follow the monthly and over year trend of the evolution of wind and wave characteristics, but face significant problems for efficient sea-state forecasting. Finally, the overall pattern of the wind/wave climate for the entire Aegean Sea as obtained from the models is presented by means of the spatial distribution of the mean annual wind and sea-state intensity. 相似文献
3.
In this paper, the wind field provided by a meso-scale atmospheric model is employed. When main physical processes, including wave-current interactions, are considered, the latest version of the third generation wave model SWAN is applied to simulate the typhoon wave generated by Typhoon Winnie. The model results are compared with the TOPEX/POSEIDON and ERS-2 satellite altimeter data and analyzed in details. Then the distribution of wave fields are analyzed, with the results showing that applying SWAN to simulate large-scale domain can also fairly reproduce the observed features of waves and realistically reflect the distribution of typhoon waves. 相似文献
4.
5.
J. C. Hargreaves D. J. T. Carter P. D. Cotton J. Wolf 《Journal of Atmospheric & Ocean Science》2002,8(1):41-66
This paper describes the development and application of a technique for using satellite altimeter measurements as boundary data to drive the nearshore spectral wave model, SWAN. The aim was to assess the impact in coastal areas of extreme events or changes in offshore climatology and to extend the usefulness of satellite altimetry further inshore.
For the purpose of verifying the technique, three test areas where both bathymetry and some in situ data were available were chosen. The technique could, potentially, be applied to any coastal location where there is bathymetric information although, as the results reported in this paper show, intelligence must be used in adapting the methodology for different sites. It is also necessary to have information on the local wind field from either models or measurements.
The experiments at the three test areas demonstrated that there is not a simple relationship between the offshore wave height climate and the inshore climate in a particular region. Important complicating factors are bathymetry, tidal range and incident wave angle. As was most clearly demonstrated in the Carmarthen Bay test area, bathymetric complexity leads to high spatial variation in the amount of wave energy dissipated close to the coast. In the study of extreme wave events described in this paper the exact value of the local wind field was not found to be critical.
This work was a first trial combining wave climatology derived from satellite altimetry with a third generation coastal wave model so was necessarily experimental. The general trends and patterns of spatial variation obtained are encouraging but there remains significant, unquantifiable uncertainty in the results. Better observations of nearshore waves, improved understanding of the joint probability distribution of water level and waves as well as more knowledge of future climate change would all improve accuracy. 相似文献
For the purpose of verifying the technique, three test areas where both bathymetry and some in situ data were available were chosen. The technique could, potentially, be applied to any coastal location where there is bathymetric information although, as the results reported in this paper show, intelligence must be used in adapting the methodology for different sites. It is also necessary to have information on the local wind field from either models or measurements.
The experiments at the three test areas demonstrated that there is not a simple relationship between the offshore wave height climate and the inshore climate in a particular region. Important complicating factors are bathymetry, tidal range and incident wave angle. As was most clearly demonstrated in the Carmarthen Bay test area, bathymetric complexity leads to high spatial variation in the amount of wave energy dissipated close to the coast. In the study of extreme wave events described in this paper the exact value of the local wind field was not found to be critical.
This work was a first trial combining wave climatology derived from satellite altimetry with a third generation coastal wave model so was necessarily experimental. The general trends and patterns of spatial variation obtained are encouraging but there remains significant, unquantifiable uncertainty in the results. Better observations of nearshore waves, improved understanding of the joint probability distribution of water level and waves as well as more knowledge of future climate change would all improve accuracy. 相似文献
6.
O. I. Komarovskaya V. V. Efimov V. S. Barabanov 《Russian Meteorology and Hydrology》2007,32(7):465-469
A method of the NCEP/NCAR reanalysis wind data recalculation using a regional atmospheric circulation model is described. A comparison of model results and satellite measurements is performed. The results of wind wave computation using the reanalysis and model winds are presented and their comparison is made. It is shown that the NCEP/NCAR reanalysis wind recalculation using a regional atmospheric circulation model removes the underestimation in the reanalysis winds, provides a better representation of the wind regime, and, consequently, gives a possibility to create the reanalysis of wind regime in the Black Sea region to be used in climate estimates. 相似文献
7.
Abstract Measurements of ocean directional wave spectra, significant wave height, and wind speed over the Grand Banks of Newfoundland were made using the combined capabilities of the radar ocean wave spectrometer (ROWS) and scanning radar altimeter (SRA). The instruments were flown aboard the NASA P‐3A aircraft in support of the Grand Banks ERS‐1 Synthetic Aperture Radar (SAR) Wave Experiment. The NASA sensors use proven techniques, which differ greatly from SAR, for estimating the directional long‐wave spectrum; thus they provide a unique set of measurements for use in evaluating SAR performance. ROWS and SRA data are combined with spectra from the SAR aboard the Canadian Centre for Remote Sensing (CCRS) CV‐580 aircraft, the first‐generation Canadian Spectral Ocean Wave Model (CSOWM) hindcast, and other available in situ measurements to assess the ERS‐1 SAR's ability to correctly resolve wave field components along a 200‐ to 300‐km flight line for four separate satellite passes. Given the complex seas present on the Grand Banks, the complementary nature of viewing the sea spectrum from the perspectives of multiple sensors and a wave prediction model is apparent. The data intercomparisons show the ERS‐1 SAR to be meeting the expected goals for measuring swell, but the data also show evidence of this remote sensor's inability to detect the shorter waves travelling in the azimuth or along‐track direction. Example SAR spectra simulations are made using a non‐linear forward transform with ROWS measurements as input. Additionally, surface wind and wave height estimates made using the ROWS altimeter channel are presented. These data demonstrate the utility of operating the system in its new combined altimeter and spectrometer configuration. 相似文献
8.
The atmospheric surface layer over sea has a density stratification which varies with moisture content and air/sea temperature difference. This influences the growth of water waves. To study the effect quantitatively, the Reynolds equations are solved numerically. For given wind speed and surface roughness, wave growth is found to be more rapid in unstably stratified conditions than in stable conditions. This is due to an increase in turbulence, primarily caused by an increase of mixing length.Under the assumption of a Charnock relation between surface roughness and friction velocity, it is found that for large inverse wave age (u
*/c>0.07), the effect of stratification on wave growth is weell described by Monin-Obukhov scaling of the friction velocity. For smaller values ofu
*/c, Monin-Obukhov scaling overpredicts.The effect on duration-limited wave growth is studied with the third-generation WAM surface wave model driven by 10 m winds. Effects of stratification on the significant wave height are found to be of the order of 10%. The results are comparable to those of a recent reanalysis of field measurements, although the measured stratification effect is somewhat stronger. Implementation of a stratification-dependent growth in wave models is recommended, as it can lead to small but significant improvements in wave forecasts when accurate air and sea temperatures are available. 相似文献
9.
10.
This study examines the variability of the monthly average significant wave height (SWH) field in the Mediterranean Sea, in
the period 1958–2001. The analysed data are provided by simulations carried out using the WAM model (WAMDI group, 1988) forced
by the wind fields of the ERA-40 (ECMWF Re-Analysis). Comparison with buoy observations, satellite data, and simulations forced
by higher resolution wind fields shows that, though results underestimate the actual SWH, they provide a reliable representation
of its real space and time variability. Principal component analysis (PCA) shows that the annual cycle is characterised by
two main empirical orthogonal functions (EOF) patterns. Most inter-monthly variability is associated with the first EOF, whose
positive/negative phase is due to the action of Mistral/Etesian wind regimes. The second EOF is related to the action of southerly
winds (Libeccio and Sirocco). The annual cycle presents two main seasons, winter and summer characterised, the first, by the
prevalence of eastwards and southeastwards propagating waves all over the basin, and the second, by high southwards propagating
waves in the Aegean Sea and Levantin Basin. Spring and fall are transitional seasons, characterised by northwards and northeastwards
propagating waves, associated to an intense meridional atmospheric circulation, and by attenuation and amplification, respectively,
of the action of Mistral. These wave field variability patterns are associated with consistent sea level pressure (SLP) and
surface wind field structures. The intensity of the SWH field shows large inter-annual and inter-decadal variability and a
statistically significant decreasing trend of mean winter values. The winter average SWH is anti-correlated with the winter
NAO (North Atlantic Oscillation) index, which shows a correspondingly increasing trend. During summer, a minor component of
the wave field inter-annual variability (associated to the second EOF) presents a statistically significant correlation with
the Indian Monsoon reflecting its influence on the meridional Mediterranean circulation. However, the SLP patterns associated
with the SWH inter-annual variability reveal structures different from NAO and Monsoon circulation. In fact, wave field variability
is conditioned by regional storminess in combination with the effect of fetch. The latter is likely to be the most important.
Therefore, the inter-annual variability of the mean SWH is associated to SLP patterns, which present their most intense features
above or close to Mediterranean region, where they are most effective for wave generation.
相似文献
| P. LionelloEmail: |
11.
The physics of the interaction of electromagnetic waves with the ocean surface has been an active area of research for a number of years. We present here the results of satellite and aircraft experiments to investigate the ability of active microwave radars to infer surface wind speeds remotely. Data obtained from the recent National Aeronautics and Space Administration (NASA) Skylab experiment are compared with surface wind speeds measured by low-flying aircraft and ships-of-opportunity and found to give useful estimates of the oceanic wind field. We also investigate the influence of varying wave height on radar measurements of wind speed by measuring the backscattering cross-section for constant wind speed but variable wave conditions. We conclude that this effect is of little importance. 相似文献
12.
The present study is conducted to verify the short-range forecasts from mesoscale model version5 (MM5)/weather research and forecasting (WRF) model over the Indian region and to examine the impact of assimilation of quick scatterometer (QSCAT) near surface winds, spectral sensor microwave imager (SSM/I) wind speed and total precipitable water (TPW) on the forecasts by these models using their three-dimensional variational (3D-Var) data assimilation scheme for a 1-month period during July 2006. The control (without satellite data assimilation) as well as 3D-Var sensitivity experiments (with assimilating satellite data) using MM5/WRF were made for 48 h starting daily at 0000 UTC July 2006. The control run is analyzed for the intercomparison of MM5/WRF short-range forecasts and is also used as a baseline for assessing the MM5/WRF 3D-Var satellite data sensitivity experiments. As compared to the observation, the MM5 (WRF) control simulations strengthened (weakened) the cross equatorial flow over southern Arabian sea near peninsular India. The forecasts from MM5 and WRF showed a warm and moist bias at lower and upper levels with a cold bias at the middle level, which shows that the convective schemes of these models may be too active during the simulation. The forecast errors in predicted wind, temperature and humidity at different levels are lesser in WRF as compared to MM5, except the temperature prediction at lower level. The rainfall pattern and prediction skill from day 1 and day 2 forecasts by WRF is superior to MM5. The spatial distribution of forecast impact for wind, temperature, and humidity from 1-month assimilation experiments during July 2006 demonstrated that on average, for 24 and 48-h forecasts, the satellite data improved the MM5/WRF initial condition, so that model errors in predicted meteorological fields got reduced. Among the experiments, MM5/WRF wind speed prediction is most benefited from QSCAT surface wind and SSM/I TPW assimilation while temperature and humidity prediction is mostly improved due to latter. The largest improvement in MM5/WRF rainfall prediction is due to the assimilation of SSM/I TPW. The assimilation of SSM/I wind speed alone in MM5/WRF degraded the humidity and rainfall prediction. In summary the assimilation of satellite data showed similar impact on MM5/WRF prediction; largest improvement due to SSM/I TPW and degradation due to SSM/I wind speed. 相似文献
13.
Jose Henrique G. M. Alves Diana J. M. Greenslade Michael L. Banner 《Journal of Atmospheric & Ocean Science》2002,8(4):239-267
The impact of a modified parametric form of the dissipation source function S ds on the skill of an operational spectral wind-wave model is investigated. Numerical experiments are made with a version of the WAM model presently used operationally by the Australian Bureau of Meteorology to produce sea-state forecasts within the Australian region. Performances of wave hindcasts obtained using several alternative forms of this newly proposed dissipation source function are compared to those produced with forms of S ds commonly used operationally. A new ad hoc technique to compare modelled and observed wave spectra is introduced to assess the quality of calculated one-dimensional frequency spectra.
Our results indicate that wave model performance in terms of integral spectral parameters, such as the significant wave height H s , may benefit from improved parameterisations of the dissipation source term S ds . On the other hand, we also found that model performance was relatively poor in terms of predictions of the one-dimensional frequency spectrum, regardless of the chosen form of S ds . These results suggest that further refinements of the dissipation source term are strongly dependent on improved parametrisations of the nonlinear interactions source term S nl . 相似文献
Our results indicate that wave model performance in terms of integral spectral parameters, such as the significant wave height H s , may benefit from improved parameterisations of the dissipation source term S ds . On the other hand, we also found that model performance was relatively poor in terms of predictions of the one-dimensional frequency spectrum, regardless of the chosen form of S ds . These results suggest that further refinements of the dissipation source term are strongly dependent on improved parametrisations of the nonlinear interactions source term S nl . 相似文献
14.
Yongkang Xue Fernando De Sales W. K.-M. Lau Aaron Boone Jinming Feng Paul Dirmeyer Zhichang Guo Kyu-Myong Kim Akio Kitoh Vadlamani Kumar Isabelle Poccard-Leclercq Natalie Mahowald Wilfran Moufouma-Okia Phillip Pegion David P. Rowell Jae Schemm Siegfried D. Schubert Andrea Sealy Wassila M. Thiaw Augustin Vintzileos Steven F. Williams Man-Li C. Wu 《Climate Dynamics》2010,35(1):3-27
This paper briefly presents the West African Monsoon (WAM) Modeling and Evaluation Project (WAMME) and evaluates WAMME general circulation models’ (GCM) performances in simulating variability of WAM precipitation, surface temperature, and major circulation features at seasonal and intraseasonal scales in the first WAMME experiment. The analyses indicate that models with specified sea surface temperature generally have reasonable simulations of the pattern of spatial distribution of WAM seasonal mean precipitation and surface temperature as well as the averaged zonal wind in latitude-height cross-section and low level circulation. But there are large differences among models in simulating spatial correlation, intensity, and variance of precipitation compared with observations. Furthermore, the majority of models fail to produce proper intensities of the African Easterly Jet (AEJ) and the tropical easterly jet. AMMA Land Surface Model Intercomparison Project (ALMIP) data are used to analyze the association between simulated surface processes and the WAM and to investigate the WAM mechanism. It has been identified that the spatial distributions of surface sensible heat flux, surface temperature, and moisture convergence are closely associated with the simulated spatial distribution of precipitation; while surface latent heat flux is closely associated with the AEJ and contributes to divergence in AEJ simulation. Common empirical orthogonal functions (CEOF) analysis is applied to characterize the WAM precipitation evolution and has identified a major WAM precipitation mode and two temperature modes (Sahara mode and Sahel mode). Results indicate that the WAMME models produce reasonable temporal evolutions of major CEOF modes but have deficiencies/uncertainties in producing variances explained by major modes. Furthermore, the CEOF analysis shows that WAM precipitation evolution is closely related to the enhanced Sahara mode and the weakened Sahel mode, supporting the evidence revealed in the analysis using ALMIP data. An analysis of variability of CEOF modes suggests that the Sahara mode leads the WAM evolution, and divergence in simulating this mode contributes to discrepancies in the precipitation simulation. 相似文献
15.
Emmanouil Flaounas Serge Janicot Sophie Bastin Rémy Roca Elsa Mohino 《Climate Dynamics》2012,38(5-6):965-983
In spring the inland penetration of the West African Monsoon (WAM) is weak and the associated rainband is located over the Guinean coast. Then within a few days deep convection weakens considerably and the rainband reappears about 20?days after over the Sahel, where it remains until late September signalling the summer rainy season. Over the period 1989–2008 a teleconnection induced by the Indian monsoon onset is shown to have a significant impact on the WAM onset, by performing composite analyses on both observational data sets and atmospheric general circulation model simulations ensembles where the model is nudged to observations over the Indian monsoon sector. The initiation of convective activity over the Indian subcontinent north of 15°N at the time of the Indian monsoon onset results in a westward propagating Rossby wave establishing over North Africa 7–15?days after. A back-trajectory analysis shows that during this period, dry air originating from the westerly subtropical jet entrance is driven to subside and move southward over West Africa inhibiting convection there. At the same time the low-level pressure field over West Africa reinforces the moisture transport inland. After the passage of the wave, the dry air intrusions weaken drastically. Hence 20?days after the Indian monsoon onset, convection is released over the Sahel where thermodynamic conditions are more favourable. This scenario is very similar in the observations and in the nudged simulations, meaning that the Indian monsoon onset is instrumental in the WAM onset and its predictability at intraseasonal scale. 相似文献
16.
利用美国国家海洋大气总局/美国国家环境预报中心（NOAA/NCEP）发布的最新版WAV-EWATCHⅢ（version3.14）海浪模式对0801号台风＂浣熊＂进行数值模拟,并在此基础上对台风浪的发展过程和台风影响下的海面有效波高、风浪场及涌浪场的分布特征进行分析。结果表明：海面有效波高的分布和演变受台风系统强度和移动的影响;台风过程中所产生的大浪主要为风浪;涌浪场的分布与风浪场的分布几乎相反,涌浪场基本分布在远离台风中心的外围海域;涌浪场波高比风浪场波高要小。 相似文献
17.
Xiaoli Guo Lars n Vladimir K. Makin Ann-Sofi Smedman 《Journal of Atmospheric & Ocean Science》2003,9(3):97-120
Measurements from the Baltic Sea and a wind-over-wave coupled model are used to study the wave impact on the sea drag. The study has been carried out for different wave conditions, namely a pure wind-sea, following-swell/ mixed sea and cross-swell/ mixed sea. Measurements reveal the fact that the sea drag is dependent on the sea-state. In stationary conditions and in the absence of severe cross-swell, swell reduces drag compared to wind-sea at the same wind speed. The cross-swell enhances the drag as compared to the following-swell case and the magnitude of the drag coefficient is increased with increasing the angle of swell propagation to the wind. It is shown that the agreement between the model results and measurements is good for pure wind-sea and stationary mixed-sea cases. Discrepancies occur at light winds, where most of the data represent pure swell conditions. During these pure swell conditions the data are characterized by a large variation of the drag coefficient. The variation is caused by mesoscale variability in the stress co-spectra, wind-cross-swell effects and nonstationarity in the wave and wind fields not represented in the model. 相似文献
18.
K. Goubanova V. Echevin B. Dewitte F. Codron K. Takahashi P. Terray M. Vrac 《Climate Dynamics》2011,36(7-8):1365-1378
The key aspect of the ocean circulation off Peru?CChile is the wind-driven upwelling of deep, cold, nutrient-rich waters that promote a rich marine ecosystem. It has been suggested that global warming may be associated with an intensification of upwelling-favorable winds. However, the lack of high-resolution long-term observations has been a limitation for a quantitative analysis of this process. In this study, we use a statistical downscaling method to assess the regional impact of climate change on the sea-surface wind over the Peru?CChile upwelling region as simulated by the global coupled general circulation model IPSL-CM4. Taking advantage of the high-resolution QuikSCAT wind product and of the NCEP reanalysis data, a statistical model based on multiple linear regressions is built for the daily mean meridional and zonal wind at 10?m for the period 2000?C2008. The large-scale 10?m wind components and sea level pressure are used as regional circulation predictors. The skill of the downscaling method is assessed by comparing with the surface wind derived from the ERS satellite measurements, with in situ wind observations collected by ICOADS and through cross-validation. It is then applied to the outputs of the IPSL-CM4 model over stabilized periods of the pre-industrial, 2?×?CO2 and 4?×?CO2 IPCC climate scenarios. The results indicate that surface along-shore winds off central Chile (off central Peru) experience a significant intensification (weakening) during Austral winter (summer) in warmer climates. This is associated with a general decrease in intra-seasonal variability. 相似文献
19.
基于TRMM卫星降雨资料、MERRA-2卫星位势高度、风速、垂直速度等资料，对1909号台风"利奇马"的移动特征及其引发浙江、江苏、山东等地暴雨进行诊断分析.分析结果发现，台风"利奇马"是北上型台风，移动路径主要受副高与1910号台风"罗莎"等系统影响.在北上的过程中，由于台风倒槽与西风槽携带的冷空气配合，且存在大量不稳定能量，引发了此次强降水过程.此外，低空急流及西风槽为降水提供了良好的动力上升条件，南海西南季风与台风"罗莎"是台风"利奇马"充沛的水汽与能量来源，为暴雨提供了良好的水汽条件. 相似文献
20.
Abstract The wind climate of the mountainous terrain in the southern Yukon is simulated using the Wind Energy Simulation Toolkit (WEST) developed by the Recherche en Prévision Numérique (RPN) group of Environment Canada and is compared to measurements in the field. WEST combines two models that operate at different spatial scales. The Mesoscale Compressible Community (MC2) model is a mesoscale numerical weather prediction model that produces simulations over large domains of the order of a thousand kilometres. The MC2 model uses long‐term synoptic scale wind climate data from the analysis of radiosonde and other observations to simulate mean wind fields at tens of metres above the ground using a horizontal resolution of a few kilometres. The mesoscale results are used as input to MS‐Micro/3 (Mason and Sykes (1979) version of the Jackson and Hunt (1975) model version for microcomputers/3‐dimensional; MS‐Micro hereafter), a more computer‐efficient, microscale model with simpler linearized momentum equations and a domain restricted to a few tens of kilometres with horizontal grid sizes of tens or hundreds of metres. MS‐Micro provides wind field results at specific wind generator hub heights (typically 30 to 50 m above ground level (AGL)) which are of interest to researchers and developers of wind farms. WEST shows relatively strong correlations between its simulated long‐term mean wind speed and the measurements from ten wind energy monitoring stations. However, in the mountainous terrain of the Yukon, WEST tends to predict wind speeds which are about 40% too high. The model also produces erroneous wind directions and some were perpendicular to valley orientations. The most likely cause of the wind speed and direction errors is the substantially modified 5‐km grid‐spaced mesoscale terrain used in MC2. The WEST simulation was also found to double the wind speeds observed at airport stations and there was poor correlation between the simulated and observed wind speeds. The bias in the model could be attributed to a number of factors, including the use of smoothed topography by the model, the discrepancy between the neutral atmosphere assumed in MS‐Micro and the normally observed stable atmosphere, the application of MS‐Micro to every third grid point of the MC2 output, abnormally high sea level wind speeds in the input climate data for MC2, and a certain degree of disagreement between the land surface characteristics used in the model and those found in the field. At comparatively low computer cost, WEST predicts a wind climate map that compares favourably to the wind measurements made in several locations in the Yukon. However, the problem of the modified terrain in the mountainous regions is the most pressing problem and needs to be addressed before WEST is used in the mountainous regions of Canada. 相似文献