共查询到20条相似文献，搜索用时 29 毫秒
1.
The long-term variations of wave characteristics in the Black Sea are evaluated by using a third-generation wave model (Simulating WAves Nearshore, SWAN), forced by the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim and National Centers for Environmental Prediction/Climate Forecast System Reanalysis (NCEP/CFSR) wind data, covering the period of 1979−2018. The model results were calibrated and validated with buoy measurements at seven stations along the Black Sea. The comparative study shows that the CFSR dataset predicted slightly greater significant wave heights than the ERA-Interim dataset. The greatest difference between two datasets in terms of wave characteristics was found in the northeastern part of the Black Sea. The long-term averages and the variations of long-term trends for wave characteristics show that southwestern part of the Black Sea was characterized by greater significant wave heights, longer mean wave periods and storm durations, and lower variability, while the northeastern part of the basin was characterized by lower significant wave heights, shorter mean wave periods and storm durations, and higher variability. The long-term trends indicate that the wave characteristics over the 40-year period are more likely to be exposed to higher variation on the eastern part of the Black Sea than the western part of the basin. 相似文献
2.
The results of computation of wind wave fields for two versions of the WAM model (the original version of the European wind wave model WAM4 and its modified version WAM4-M) are compared with satellite measurements. The mapped data on the daily averaged wave height obtained from the data of combined measurements of several satellite altimeters are used. Significant correlation between wind wave series for both models and satellite data is demonstrated as well as the advantage of the WAM4-M model over its original version in accuracy and some statistical parameters of comparison with the altimeter. Advantages and shortcomings of numerical and remote sensing methods of wind wave investigation at the ocean scales are noted. 相似文献
3.
Walter C. Dragani Paula B. Martin Guadalupe Alonso Jorge O. Codignotto Bárbara E. Prario Guido Bacino 《Climatic change》2013,121(4):649-660
Several works reported wind-wave climate changes at Buenos Aires Province continental shelf. The aim of this work is to investigate the impact of these changes in the coastal processes of the region. This study is carried out by means of visual wave parameters gathered at the surf zone of Pinamar and by a conveniently implemented and validated numerical wave model (SWAN). Numerical results corresponding to a grid point located 30 km off Pinamar show a significant increase of wave heights from the S and SSE directions and in the frequency of occurrence of waves coming from the S, SSE and E. It is shown that these slight offshore appreciated trends would not have significant effects on the breaker heights observed at the surf zone at Pinamar. On the contrary, the slight positive trend observed offshore in the frequency of occurrence could be affecting the incidence of waves onshore, producing an increase in the number of cases of normal incidence at the surf zone and, consequently, a significant decrease in the alongshore wave energy flux assessed at Pinamar. This reduction in the alongshore wave energy flux could be responsible for some coastal changes detected in the region as, for instance, the remarkable shortening of Punta Rasa spit located 70 km northward Pinamar. 相似文献
4.
Abstract In this study, a 24‐h high‐resolution numerical prediction of a prefrontal squall line associated with the 14 July 1987 Montreal flood is employed to investigate the origin and role of mesoscale gravity waves in the development of the squall system. The 24‐h integration using an improved mesoscale version of the Canadian regional finite‐element model is first validated against available observations; then non‐observable features are diagnosed to reveal the relationship between deep convection and gravity wave events. It is shown that the model reproduces well many aspects of the squall line, such as the propagation and organization of the convective system, as well as its associated precipitation. It is found that gravity waves are first excited near Lake Erie, following the initiation of early convective activity. Then, these waves propagate eastward and northeastward at speeds of 20 and 35 m s‐1, respectively. As the waves propagate downstream, deep convection radiates rapidly behind the wave trough axis, forming a long line of squall convection. Because the squall line moves with the gravity waves in a “phase‐locked” manner, deep convection has a significant influence on the structure and amplitude of the gravity waves. The sensitivity of the wave‐squall prediction to various parameters in convective parameterization is also examined. 相似文献
5.
T.J. Simons 《大气与海洋》2013,51(4):169-179
Numerical models were used to compute water circulations throughout the 1970 shipping season for Lake Erie and for the 1972 International Field Year on Lake Ontario. Simultaneous computations of surface elevations were compared with observed water levels to adjust the model results after the fact. As a by‐product of these simultations, effective stress coefficients over water can be estimated. The results support earlier evidence that the effective wind stress over water is larger than indicated by atmospheric boundary layer measurements. 相似文献
6.
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
7.
Knowledge of the likely future wind, wave and surge climate in Liverpool Bay is of importance for coastal flood defence management.
We examine a 140-year time series (1960–2100) of wind and wave model projections at the WaveNet buoy location in Liverpool
Bay and also of surge model projection at two ports in Liverpool Bay, namely Liverpool and Heysham. To this end we use model
projections from the UK Climate Projections 09 (UKCP09) programme. We use a medium emissions scenario ensemble from the HadCM3
climate model sensitivity tests. A continental shelf model (CS3) with ~12 km resolution was used to separately simulate the
waves and the surge. The models are forced by hourly wind and pressure data from the Met Office (Hadley Centre) regional climate
model (RCM). Swell wave boundary conditions are generated over the full Atlantic using global climate model (GCM) winds. Analysis
of significant changes in the statistics over time shows that there is little change in extreme wave and surge conditions
in Liverpool Bay. Although there is a slight increase in the severity of the most extreme events, the frequency of extreme
wind and wave events is slightly reduced, while the frequency of extreme surge events slightly increases over the 140-year
period. From the model projections, we find that the trends in the local wind are directly reflected in the wave field within
Liverpool Bay. The trends in the skew surge projections deviate slightly from those in the wind patterns. 相似文献
8.
Abstract During the Labrador Ice Margin Experiments, LIMEX ‘87 in March 1987 and LIMEX ‘89 in March and April 1989, the Canada Centre for Remote Sensing (CCRS) CV‐580 aircraft collected synthetic aperture radar (SAR) image data over the marginal ice zone off the east coast of Newfoundland, Canada. One aspect of these experimental programs was the observation of ocean waves penetrating into the marginal ice zone (MIZ). Based upon directional wavenumber spectra derived from SAR image data, the wave attenuation rate is estimated using SAR image spectra and compared with predictions from a model developed by Liu and Mollo‐Christensen (1988). The wave and ice conditions were considerably different in LIMEX ‘87 and LIMEX ‘89. However, the model‐data comparisons are very good for all ice conditions observed. Both the model and the SAR‐derived wave attenuation rates show a characteristic roll‐over at high wavenumbers. A model for the eddy viscosity is proposed, using dimensional analysis, as a simple function of ice roughness and wave‐induced velocity. Eddy viscosities derived from SAR and wave buoy data for the wave attenuation rate show a trend that is consistent with the proposed model. 相似文献
9.
Observations and numerical modelling of Lake Ontario breezes 总被引：1，自引：0，他引：1
Abstract Analysis of two years of land‐based data shows that the Lake Ontario breeze develops on 30% of the days during summer. It typically develops in mid‐morning and persists until the late evening when it is replaced by a well developed land‐breeze regime. Simulations of 4 cases with the Colorado State University mesoscale model show good agreement with observations and suggest that local lake breezes are strongly influenced by adjacent water bodies (e.g. Lake Erie), the elongated shape of the lake, and the large‐scale wind direction. With gradient flows across the long axis of the lake, a broad band of along‐lake flow develops during the afternoon (easterly winds during southerly gradient flows and westerly winds during northerly gradient flows). Furthermore, during west‐to‐northwesterly gradient flow a nocturnal cyclonic eddy is predicted at the western end of the lake. These results imply that wind‐field models applied in the vicinity of Lake Ontario should incorporate the entire lake in their modelling domain. 相似文献
10.
In this study, projections of seasonal means and extremes of ocean wave heights were made using projections of sea level pressure
fields conducted with three global climate models for three forcing-scenarios. For each forcing-scenario, the three climate
models’ projections were combined to estimate the multi-model mean projection of climate change. The relative importance of
the variability in the projected wave heights that is due to the forcing prescribed in a forcing-scenario was assessed on
the basis of ensemble simulations conducted with the Canadian coupled climate model CGCM2. The uncertainties in the projections
of wave heights that are due to differences among the climate models and/or among the forcing-scenarios were characterized.
The results show that the multi-model mean projection of climate change has patterns similar to those derived from using the
CGCM2 projections alone, but the magnitudes of changes are generally smaller in the boreal oceans but larger in the region
nearby the Antarctic coastal zone. The forcing-induced variance (as simulated by CGCM2) was identified to be of substantial
magnitude in some areas in all seasons. The uncertainty due to differences among the forcing-scenarios is much smaller than
that due to differences among the climate models, although it was identified to be statistically significant in most areas
of the oceans (this indicates that different forcing conditions do make notable differences in the wave height climate change
projection). The sum of the model and forcing-scenario uncertainties is smaller in the JFM and AMJ seasons than in other seasons,
and it is generally small in the mid-high latitudes and large in the tropics. In particular, some areas in the northern oceans
were projected to have large changes by all the three climate models. 相似文献
11.
A sensitivity analysis of the parameterizations of vertical mixing and radiative fluxes on the seasonal evolution of Lake Erie's thermal structure is performed using the Massachusetts Institute of Technology general circulation model (MITgcm) and the General Estuarine Transport Model (GETM). The models have the same horizontal resolution and are forced with observed meteorological data from April to October of 2002 and 2008. For turbid waters like Lake Erie, the three-band model for the parameterization of downward shortwave radiation produces more accurate temperatures in the thermocline and less error in simulating the mixed-layer depths than the widely used two-band model. Although the two models differ in vertical and horizontal mixing, numerical methods, and vertical discretization, they produced qualitatively comparable results. Comparison with observations shows that the models can reproduce the time evolution of the lake temperature reasonably well. The MITgcm and the GETM with the Mellor-Yamada level 2.5 (MY2.5) closure produce a deeper mixed layer than observed at a station located in the eastern basin, causing large errors in simulating the temperature in the thermocline while the GETM, using a turbulence scheme called “gen,” reproduces a mixed layer in better agreement with observations. The mixed-layer obtained with the k-ε closure is between those obtained with gen and MY2.5. The error in simulating the mixed-layer depths and the thermocline temperature at a station located in the central basin using the gen closure and the GETM was about 2°C lower than that obtained by the K-Profile Parameterization mixing scheme of the MITgcm. The models simulated a lake-wide anticyclonic circulation occupying the southwest part of the central basin but showed distinct differences in simulating gyres in the northwestern part of the central basin and in the eastern basin of the lake. The signature of a basin-scale Poincaré wave observed in the current data is also well represented by the two models. 相似文献
12.
《大气与海洋》2013,51(4):415-427
Abstract An Mw = 7.2 earthquake occurred on 15 June 2005 (utc) seaward of northern California off the west coast of North America. Based on the earthquake location and source parameters, the West Coast and Alaska Tsunami Warning Center issued a tsunami warning for the region extending from the California‐Mexico border to northern Vancouver Island, British Columbia (the first tsunami warning for this region since the 1994 Mw = 8.2 Shikotan earthquake). Six tide gauges on the west coast recorded tsunami waves from this event, with a maximum trough‐to‐crest wave height of 27.7 cm observed at Crescent City, California. Waves of 2.5 to 6.5 cm were measured at the five other sites: Port Orford (Oregon), North Spit and Arena Cove (California), and Tofino and Bamfield (British Columbia). The open‐ocean Deep‐ocean Assessment and Reporting of Tsunami (DART) buoys, 46404 and 46405, recorded tsunami waves of 0.5 and 1.5 cm, respectively, closely matching wave heights derived from numerical models. Incoming tsunami wave energy was mainly at periods of 10 to 40 min. The observed tsunami wave field is interpreted in terms of edge (trapped) and leaky (non‐trapped) waves and a “trapping coefficient” is introduced to estimate the relative contribution of these two wave types. Due to the high (3000 m) water depth in the source area, approximately two‐thirds of the total tsunami energy went to leaky wave modes and only one‐third to edge wave modes. The improved response to and preparedness for the 2005 California tsunami compared to the 1994 Shikotan tsunami is attributable, in part, to the operational capability provided by the open‐ocean bottom‐pressure recorder (DART) system, higher quality coastal tide gauges, and the effective use of numerical models to simulate real‐time tsunamis. 相似文献
13.
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
14.
Denamiel Cléa Pranić Petra Quentin Florent Mihanović Hrvoje Vilibić Ivica 《Climate Dynamics》2020,55(9-10):2483-2509
This numerical work aims to better understand the behavior of extreme Adriatic Sea wave storms under projected climate change. In this spirit, 36 characteristic events—22 bora and 14 sirocco storms occurring between 1979 and 2019, were selected and ran in evaluation mode in order to estimate the skill of the kilometer-scale Adriatic Sea and Coast (AdriSC) modelling suite used in this study and to provide baseline conditions for the climate change impact. The pseudo-global warming (PGW) methodology—which imposes an additional climatological change to the forcing used in the evaluation simulations, was implemented, for the very first time, for a coupled ocean–wave–atmosphere model and used to assess the behavior of the selected storms under Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 greenhouse gas projections. The findings of this experiment are that, on the one hand, the AdriSC model is found capable of reproducing both the Adriatic waves associated with the 36 storms and the northern Adriatic surges occurring during the sirocco events and, on the other hand, the significant wave heights and peak periods are likely to decrease during all future extreme events but most particularly during bora storms. The northern Adriatic storm surges are in consequence also likely to decrease during sirocco events. As it was previously demonstrated that the Adriatic extreme wind-wave events are likely to be less intense in a future warmer climate, this study also proved the validity of applying the PGW methodology to coupled ocean–wave–atmosphere models at the coastal and nearshore scales.
相似文献15.
为了提高对黄渤海海雾天气海面大气水平能见度（以下简称“能见度”）的数值预报能力,利用黄渤海23个沿岸和岛屿测站2013—2017年雾天的地面观测数据,构建了基于湿度信息的能见度算法（A-F算法）,并将之应用于黄渤海海雾的能见度数值预报。结果表明,与常用的根据模式预报的云水含量诊断能见度的SW算法（Stoelinga and Warner,1999）相比,A-F算法表现更优,尤其可以诊断出被SW算法漏报的能见度为1～3 km的轻雾,说明A-F算法对黄渤海海雾天气能见度的数值预报具有一定应用价值。若将来加入浮标与船舶观测数据,可以进一步改进A-F算法能见度公式的具体形式;依据本文构建A-F算法的思路,可以发展适合其他海域的海雾天气能见度诊断公式。 相似文献
16.
基于西北地区东部81站1961—2010年夏季(6—8月)逐月降水资料和NCEP/NCAR再分析资料,利用距平合成分析,探讨其多雨年和少雨年逐月500 hPa高度场和700 hPa湿度场特征。结果表明:西北地区东部多雨年,影响降水的天气特征表现为乌拉尔山脊逐月偏强,7月鄂霍次克海脊偏强,贝加尔湖高压脊转为低槽,7月巴尔喀什湖低槽较6月偏强。8月贝加尔湖长波槽较7月偏强;少雨年天气系统表现为6—8月西北地区东部受高压脊前西北气流控制。西太平洋副热带高压(以下简称:副高)多雨年较少雨年偏西偏强。6—8月多(少)雨年比湿的变化表明,西北地区东部降水多雨年,大气的含水量较高,西北地区东部降水少雨年,大气的含水量较低。 相似文献
17.
Wave-dependence of friction velocity,roughness length,and drag coefficient over coastal and open water surfaces by using three databases 总被引：3，自引：0，他引：3
The parameterization of friction velocity, roughness length, and the drag coefficient over coastal
zones and open water surfaces enables us to better understand the physical processes of air-water interaction.
In context of measurements from the Humidity Exchange over the Sea Main Experiment (HEXMAX), we recently proposed
wave-parameter dependent approaches to sea surface friction velocity and the aerodynamic roughness by using the
dimensional analysis method. To extend the application of these approaches to a range of natural surface conditions,
the present study is to assess this approach by using both coastal shallow (RASEX) and open water surface measurements
(Lake Ontario and Grand Banks ERS-1 SAR) where wind speeds were greater than 6.44 m s-1. Friction velocities,
the surface aerodynamic roughness, and the neutral drag coefficient estimated by these approaches under moderate wind
conditions were compared with the measurements mentioned above. Results showed that the coefficients in these approaches
for coastal shallow water surface differ from those for open water surfaces, and that the aerodynamic roughness length
in terms of wave age or significant wave height should be treated differently for coastal shallow and open water surfaces. 相似文献
18.
Abstract The design of a spar buoy, employed as one component of a current monitoring system deployed during 1980 in Davis Strait, and some of its response characteristics to ocean waves are presented. The buoy was 36.5 ft (11.13 m) in length with upper and lower masts 0.5ft (15.2 cm) in diameter and buoyancy hulls, centrally located, 2 ft (61.0 cm) in diameter. Power for the system was supplied from lead‐acid batteries in a ballast tank on the lower end. Telemetry electronics were located in a 1‐ft (30.5‐cm) diameter case on the upper end, below the antenna. The buoy weighed about 1,635 lb (746kg) and could be man‐handled at sea with relatively light lifting equipment. It had a damped period of 16s and a significant heave response of about 62% of the significant wave height of the forcing spectrum. Scale model tests indicated that the buoy would be operational in heavy sea swell up to about 20ft in height with pitching angles of less than 10° off vertical. Observations at sea have shown that the buoy followed swell waves better than the 62% heave response figure would imply and had negligible pitching motions except during severe storms. The design was judged to be successful in providing a stable base for VHF transmission and is recommended for use in other applications. 相似文献
19.
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
20.