共查询到20条相似文献，搜索用时 31 毫秒
1.
On recording sea surface elevation with accelerometer buoys: lessons from ITOP (2010) 总被引：2，自引：2，他引：0
Measurements of significant wave height are made routinely throughout the world’s oceans, but a record of the sea surface elevation (η) is rarely kept. This is mostly due to memory limitations on data, but also, it is thought that buoy measurements of sea surface elevation are not as accurate as wave gauges mounted on stationary platforms. Accurate records of η which contain rogue waves (defined here as an individual wave at least twice the significant wave height) are of great interest to scientists and engineers. Using field data, procedures for tilt correcting and double integrating accelerometer data to produce a consistent record of η are given in this study. The data in this study are from experimental buoys deployed in the recent Impact of Typhoons on the Ocean in the Pacific (ITOP) field experiment which occurred in 2010. The statistics from the ITOP buoys is under that predicted by Rayleigh theory, but matches the distributions of Boccotti and others (Tayfun and Fedele) (Ocean Eng 34:1631-1649, 2007). Rogue waves were recorded throughout the experiment under various sea state conditions. Recommendations, as a result of lessons learned during ITOP, are made for the routine recording of η which may not add significantly to the existing data burden. The hope is that we might one day collect a worldwide database of rogue waves from the existing buoy network, which would progress our understanding of the rogue wave phenomenon and make work at sea safer. 相似文献
2.
A new methodology for the extension of the impact of data assimilation on ocean wave prediction 总被引：1，自引：1，他引：0
It is a common fact that the majority of today's wave assimilation platforms have a limited, in time, ability of affecting
the final wave prediction, especially that of long-period forecasting systems. This is mainly due to the fact that after “closing”
the assimilation window, i.e., the time that the available observations are assimilated into the wave model, the latter continues
to run without any external information. Therefore, if a systematic divergence from the observations occurs, only a limited
portion of the forecasting period will be improved. A way of dealing with this drawback is proposed in this study: A combination
of two different statistical tools—Kolmogorov–Zurbenko and Kalman filters—is employed so as to eliminate any systematic error
of (a first run of) the wave model results. Then, the obtained forecasts are used as artificial observations that can be assimilated
to a follow-up model simulation inside the forecasting period. The method was successfully applied to an open sea area (Pacific
Ocean) for significant wave height forecasts using the wave model WAM and six different buoys as observational stations. The
results were encouraging and led to the extension of the assimilation impact to the entire forecasting period as well as to
a significant reduction of the forecast bias. 相似文献
3.
Takehiko Nose Adrean Webb Takuji Waseda Jun Inoue Kazutoshi Sato 《Ocean Dynamics》2018,68(10):1383-1402
A predictability study on wave forecast of the Arctic Ocean is necessary to help identify hazardous areas and ensure sustainable shipping along the trans-Arctic routes. To assist with validation of the Arctic Ocean wave model, two drifting wave buoys were deployed off Point Barrow, Alaska for two months in September 2016. Both buoys measured significant wave heights exceeding 4 m during two different storm events on 19 September and 22 October. The NOAA-WAVEWATCH III? model with 16-km resolution was forced using wind and sea ice reanalysis data and obtained general agreement with the observation. The September storm was reproduced well; however, model accuracy deteriorated in October with a negative wave height bias of around 1 m during the October storm. Utilising reanalysis data, including the most up-to-date ERA5, this study investigated the cause: grid resolution, wind and ice forcing, and in situ sea level pressure observations assimilated for reanalysis. The analysis has found that there is a 20% reduction of in situ SLP observations in the area of interest, presumably due to fewer ships and deployment options during the sea ice advance period. The 63-member atmospheric ensemble reanalysis, ALERA2, has shown that this led to a larger ensemble spread in the October monthly mean wind field compared to September. Since atmospheric physics is complex during sea ice advance, it is speculated that the elevated uncertainty of synoptic-scale wind caused the negative wave model bias. This has implications for wave hindcasts and forecasts in the Arctic Ocean. 相似文献
4.
OSMAR2003岸基高频地波雷达系统由武汉大学电波传播实验室研制并于2005年应用于福建沿海,能够全天候、大面积探测台湾海峡内海洋表面动力学要素. 本文首先将0519号台风期间高频地波雷达的测量数据与局部点的浮标数据对比，然后又对大面积海域内雷达测量风场与uikSCAT卫星遥感数据进行了对比分析. 结果表明高频地波雷达较好地反映了台风期间台湾海峡内风场的空间分布及其发展变化情况，具有一定的灾害性海洋天气监测能力. 相似文献
5.
Spatial characteristics of ocean surface waves 总被引：2，自引：2，他引：0
Johannes Gemmrich Jim Thomson W. Erick Rogers Andrey Pleskachevsky Susanne Lehner 《Ocean Dynamics》2016,66(8):1025-1035
The spatial variability of open ocean wave fields on scales of O (10km) is assessed from four different data sources: TerraSAR-X SAR imagery, four drifting SWIFT buoys, a moored waverider buoy, and WAVEWATCH III? model runs. Two examples from the open north-east Pacific, comprising of a pure wind sea and a mixed sea with swell, are given. Wave parameters attained from observations have a natural variability, which decreases with increasing record length or acquisition area. The retrieval of dominant wave scales from point observations and model output are inherently different to dominant scales retrieved from spatial observations. This can lead to significant differences in the dominant steepness associated with a given wave field. These uncertainties have to be taken into account when models are assessed against observations or when new wave retrieval algorithms from spatial or temporal data are tested. However, there is evidence of abrupt changes in wave field characteristics that are larger than the expected methodological uncertainties. 相似文献
6.
One of the main challenges of the Copernicus Marine Service is the implementation of coupled ocean/waves systems that accurately estimate the momentum and energy fluxes provided by the atmosphere to the ocean. This study aims to investigate the impact of forcing the Nucleus for European Modelling of the Ocean (NEMO) ocean model with forecasts from the wave model of Météo-France (MFWAM) to improve classical air-sea flux parametrizations, these latter being mostly driven by the 10-m wind. Three wave-related processes, namely, wave-state-dependent stress, Stokes drift-related effects (Stokes-Coriolis force, Stokes drift advection on tracers and on mass), and wave-state-dependent surface turbulence, are examined at a global scale with a horizontal resolution of 0.25°. Three years of sensitivity simulations (2014–2016) show positive feedback on sea surface temperature (SST) and currents when the wave model is used. A significant reduction in SST bias is observed in the tropical Atlantic Ocean. This is mainly due to the more realistic momentum flux provided by the wave model. In mid-latitudes, the most interesting impact occurs during the summer stratification, when the wind is low and the wave model produces a reduction in the turbulence linked with wave breaking. Magnitudes of the large-scale currents in the equatorial region are also improved by 10% compared to observations. In general, it is shown that using the wave model reduces on average the momentum and energy fluxes to the ocean in tropical regions, but increases them in mid-latitudes. These differences are in the order of 10 to 20% compared with the classical parametrizations found in stand-alone ocean models. 相似文献
7.
Current methodology of environmental impact assessment in connection with the environmental consequences of hydrocarbons production in the shelf area is analyzed. Basing on the ecosystem approach, a scheme of environmental impact estimates is suggested, envisaging the use of a set of gradations (scales) to characterize spatial and temporal scope of impacts and their consequences, as well as criteria (thresholds) of impact permissibility, taking into account the natural variability in the population and ecosystem parameters. Estimates of the environmental and fishery-related consequences of hydrocarbon production in the sea shelf area at different stages of the process are compared to the available measured and calculated data. The suggested scheme of environmental impact assessment and criteria of permissible impacts are recommended for expert analysis, forecasting, and monitoring of the environmental situation in the sea shelf areas of Russia under the conditions of anthropogenic impact. 相似文献
8.
9.
The signal measured by heave–pitch–roll directional wave buoys yields the first four coefficients of a Fourier series. Data adaptive methods must be employed to estimate a directional wave spectrum. Marine X-band radars (MRs) have the advantage over buoys that they can measure “model-free” two-dimensional (2D) wave spectra. This study presents the first comprehensive validation of MR-derived multi-directional wave characteristics. It is based on wave data from the 2010 Impact of Typhoons on the Ocean in the Pacific (ITOP) experiment in the Philippine Sea, namely MR measurements from R/V Roger Revelle, Extreme Air–Sea Interaction (EASI) buoy measurements, as well as WAVEWATCH-III (WW3) modeling results. Buoy measurements of mean direction and spreading as function of frequency, which do not require data adaptive methods, are used to validate the WW3 wave spectra. An advanced MR wave retrieval technique is introduced that addresses various shortcomings of existing methods. Spectral partitioning techniques, applied to MR and WW3 results, reveal that multimodal seas are frequently present. Both data sets are in excellent agreement, tracking the evolution of up to 4 simultaneous wave systems over extended time periods. This study demonstrates MR’s and WW3’s strength at measuring and predicting 2D wave spectra in swell-dominated seas. 相似文献
10.
Ocean Dynamics - Wave energy assessment at a regional scale is required for planning installation of wave energy converters. Based on continuously measured wave data at 14-m water depth in the... 相似文献
11.
A high-resolution real-time forecasting system for predicting the fate of oil spills in the Strait of Bonifacio (western Mediterranean Sea) 总被引：1，自引：0，他引：1
Cucco A Sinerchia M Ribotti A Olita A Fazioli L Perilli A Sorgente B Borghini M Schroeder K Sorgente R 《Marine pollution bulletin》2012,64(6):1186-1200
The Strait of Bonifacio is a long and narrow area between Corsica and Sardinia. To manage environmental emergencies related to the spill of oil from vessels, an innovative forecasting system was developed. This tool is capable of operationally predicting the dispersion of hydrocarbon spills in the coastal area of the Bonifacio Strait, either from an instantaneous or continuous spill and either in forward or backward mode. Experimental datasets, including ADCP water current measurements and the trajectories of drifter buoys released in the area, were used to evaluate the accuracy of this system. A comparison between the simulation results and experimental data revealed that both the water circulation and the surface transport processes are accurately reproduced by the model. The overall accuracy of the system in reproducing the transport of an oil spill at sea was estimated for both forward and backward prediction mode and in relation to different forecasting time lags. 相似文献
12.
This paper investigates the feasibility of an ocean data assimilation system to analyze the salinity variability associated with the barrier layer in the equatorial Pacific. In order to validate reproducibility of the temperature and salinity fields, we perform an assimilation run where some temperature and salinity observations by TRITON buoys and Argo floats are withheld. The assimilation run reproduces interannual variability of salinity in the equatorial Pacific exhibited in the data that are withheld. Statistics shows that salinity values and variations in the assimilation run are closer to the data than the climatology and in the model free run. We also confirm that zonal currents in the equatorial Pacific in the reanalysis, where all available temperature and salinity data are assimilated, are consistent with an observation-based mapping and the data of the Acoustic Doppler Current Profiler mounted on TAO buoys. Variability of the barrier layer and relevant salinity field in the reanalysis is consistent with former studies. A thick barrier layer area generally exists west of the equatorial salinity front and is displaced zonally with the migration of the front in the response to El Niño-Southern Oscillation, although the area moved to the east over the front in the 1997 El Niño. It is confirmed that the barrier layer thickness is closely correlated with the near-surface temperature in the equatorial Pacific. 相似文献
13.
Comparison of numerical hindcasted severe waves with Doppler radar measurements in the North Sea 总被引：1，自引：1，他引：0
Severe sea states in the North Sea present a challenge to wave forecasting systems and a threat to offshore installations such as oil and gas platforms and offshore wind farms. Here, we study the ability of a third-generation spectral wave model to reproduce winter sea states in the North Sea. Measured and modeled time series of integral wave parameters and directional wave spectra are compared for a 12-day period in the winter of 2013–2014 when successive severe storms moved across the North Atlantic and the North Sea. Records were obtained from a Doppler radar and wave buoys. The hindcast was performed with the WAVEWATCH III model (Tolman 2014) with high spectral resolution both in frequency and direction. A good general agreement was obtained for integrated parameters, but discrepancies were found to occur in spectral shapes. 相似文献
14.
快速准确的海啸源模型是近场海啸精确预警的关键.尽管目前还没有办法直接对其进行正演定量计算,但是可以通过多源地震、海啸观测数据进行反演或联合反演推算.不同的海啸源可能导致不同的预警结论,了解不同类型海啸源适用性、评估海啸源特征差异对近场海啸的影响,无论对于海啸预警还是海啸模拟研究尤为重要.本文评估分析了6种不同同震断层模型对2011年3月11日日本东北地震海啸近场数值预报的影响,重点对比分析了有限断层模型与均一滑动场模型对近场海啸产生、传播、淹没特征的影响及各自的误差.研究表明:近场海啸波能量分布主要取决于海啸源分布特征,特别是走向角的差异对海啸能量分布影响较大;有限断层模型对海啸灾害最为严重的39°N以南沿岸地区的最大海啸爬坡高度明显优于均一滑动场模型结果;综合对比DART浮标、GPS浮标及近岸潮位站共32个站次的海啸波幅序列结果发现有限断层模型整体平均绝对/相对误差比均一滑动场模型平均误差要低,其中Fujii海啸源的平均绝对/相对误差最小,分别是0.56m和26.71%.UCSB海啸源的平均绝对/相对误差次之.3个均一滑动场模型中USGSCMT海啸源模拟精度最高.相对于深海、浅海观测站,有限断层模型比均一滑动场模型对近岸观测站计算精度更高.海啸源误差具有显著的方向性,可能与反演所采用的波形数据的代表性有关;谱分析结果表明Fujii海啸源对在12至60min主频波谱的模拟要优于UCSB海啸源.海啸源中很难真实反映海底地震破裂过程,然而通过联合反演海啸波形数据推算海啸源的方法可以快速确定海啸源,并且最大限度的降低地震破裂过程与海啸产生的不确定性带来的误差. 相似文献
15.
Observations of turbulent dissipation rates measured by two independent instruments are compared with numerical model runs to investigate the injection of turbulence generated by sea surface gravity waves. The near-surface observations are made by a moored autonomous instrument, fixed at approximately 8 m below the sea surface. The instrument is equipped with shear probes, a high-resolution pressure sensor, and an inertial motion package to measure time series of dissipation rate and nondirectional surface wave energy spectrum. A free-falling profiler is used additionally to collect vertical microstructure profiles in the upper ocean. For the model simulations, we use a one-dimensional mixed layer model based on a k–ε type second moment turbulence closure, which is modified to include the effects of wave breaking and Langmuir cells. The dissipation rates obtained using the modified k–ε model are elevated near the sea surface and in the upper water column, consistent with the measurements, mainly as a result of wave breaking at the surface, and energy drawn from wave field to the mean flow by Stokes drift. The agreement between observed and simulated turbulent quantities is fairly good, especially when the Stokes production is taken into account. 相似文献
16.
Elodie Charles Déborah Idier Pascale Delecluse Michel Déqué Gonéri Le Cozannet 《Ocean Dynamics》2012,62(6):831-848
The knowledge of offshore and coastal wave climate evolution towards the end of the twenty-first century is particularly important for human activities in a region such as the Bay of Biscay and the French Atlantic coast. Using dynamical downscaling, a high spatial resolution dataset of wave conditions in the Bay of Biscay is built for three future greenhouse gases emission scenarios. Projected wave heights, periods and directions are analysed at regional scale and more thoroughly at two buoys positions, offshore and along the coast. A general decrease of wave heights is identified (up to ?20?cm during summer within the Bay off Biscay), as well as a clockwise shift of summer waves and winter swell coming from direction. The relation between those changes and wind changes is investigated and highlights a complex association of processes at several spatial scales. For instance, the intensification and the northeastward shift of strong wind core in the North Atlantic Ocean explain the clockwise shift of winter swell directions. During summer, the decrease of the westerly winds in the Bay of Biscay explains the clockwise shift and the wave height decrease of wind sea and intermediate waves. Finally, the analysis reveals that the offshore changes in the wave height and the wave period as well as the clockwise shift in the wave direction continue toward the coast. This wave height decrease result is consistent with other regional projections and would impact the coastal dynamics by reducing the longshore sediment flux. 相似文献
17.
海平面对大气压变化的响应在理想情况下接近均衡态海洋响应.在这个假设下,任何海域的大气压变化都会瞬时传播到整个海洋上.通过比较大气压和海平面变化的标准差,可以发现,在空间尺度上,大气压变化主要是长波信号,而海平面变化除了长波信号外,还存在明显的短波长信号.由大气压变化驱动的海平面变化应与大气压变化在空间尺度上具有一致性.因此,可以对海平面数据进行空间高斯低通滤波,来得到与大气压变化更相近的空间标准差分布.通过阶振幅谱分析,表明海平面对大气压变化响应的空间尺度为800 km. 相似文献
18.
L. Eymard S. Planton P. Durand C. Le Visage P. Y. Le Traon L. Prieur A. Weill D. Hauser J. Rolland J. Pelon F. Baudin B. Bénech J. L. Brenguier G. Caniaux P. De Mey E. Dombrowski A. Druilhet H. Dupuis B. Ferret C. Flamant P. Flamant F. Hernandez D. Jourdan K. Katsaros D. Lambert J. M. Lefèvre P. Le Borgne B. Le Squere A. Marsoin H. Roquet J. Tournadre V. Trouillet A. Tychensky B. Zakardjian 《Annales Geophysicae》1996,14(9):986-1015
The SEMAPHORE (Structure des Echanges Mer-Atmosphère, Propriétés des Hétérogénéités Océaniques: Recherche Expérimentale) experiment has been conducted from June to November 1993 in the Northeast Atlantic between the Azores and Madeira. It was centered on the study of the mesoscale ocean circulation and air-sea interactions. The experimental investigation was achieved at the mesoscale using moorings, floats, and ship hydrological survey, and at a smaller scale by one dedicated ship, two instrumented aircraft, and surface drifting buoys, for one and a half month in October-November (IOP: intense observing period). Observations from meteorological operational satellites as well as spaceborne microwave sensors were used in complement. The main studies undertaken concern the mesoscale ocean, the upper ocean, the atmospheric boundary layer, and the sea surface, and first results are presented for the various topics. From data analysis and model simulations, the main characteristics of the ocean circulation were deduced, showing the close relationship between the Azores front meander and the occurrence of Mediterranean water lenses (meddies), and the shift between the Azores current frontal signature at the surface and within the thermocline. Using drifting buoys and ship data in the upper ocean, the gap between the scales of the atmospheric forcing and the oceanic variability was made evident. A 2 °C decrease and a 40-m deepening of the mixed layer were measured within the IOP, associated with a heating loss of about 100 W m−2. This evolution was shown to be strongly connected to the occurrence of storms at the beginning and the end of October. Above the surface, turbulent measurements from ship and aircraft were analyzed across the surface thermal front, showing a 30% difference in heat fluxes between both sides during a 4-day period, and the respective contributions of the wind and the surface temperature were evaluated. The classical momentum flux bulk parameterization was found to fail in low wind and unstable conditions. Finally, the sea surface was investigated using airborne and satellite radars and wave buoys. A wave model, operationally used, was found to get better results compared with radar and wave-buoy measurements, when initialized using an improved wind field, obtained by assimilating satellite and buoy wind data in a meteorological model. A detailed analysis of a 2-day period showed that the swell component, propagating from a far source area, is underestimated in the wave model. A data base has been created, containing all experimental measurements. It will allow us to pursue the interpretation of observations and to test model simulations in the ocean, at the surface and in the atmospheric boundary layer, and to investigate the ocean-atmosphere coupling at the local and mesoscales. 相似文献
19.
A comprehensive study is performed on the dynamic behavior of offshore wind turbine (OWT) structure supported on monopile foundation in clay. The system is modeled using a beam on nonlinear Winkler foundation model. Soil resistance is modeled using American Petroleum Institute based cyclic p–y and t–z curves. Dynamic analysis is carried out in time domain using finite element method considering wind and wave loads. Several parameters, such as soil–monopile–tower interaction, rotor and wave frequencies, wind and wave loading parameters, and length, diameter and thickness of monopile affecting the dynamic characteristics of OWT system and the responses are investigated. The study shows soil–monopile–tower interaction increases response of tower and monopile. Soil nonlinearity increases the system response at higher wind speed. Rotor frequency is found to have dominant role than blade passing frequency and wave frequency. Magnitude of wave load is important for design rather than resonance from wave frequency. 相似文献
20.
《Marine pollution bulletin》2014,78(1-2):102-109
Measuring loads of bioavailable metals is important for environmental assessment near mines and other industrial sources. In this study, a setup of monitoring buoys was tested to assess loads of bioavailable metals near a former Pb–Zn mine in West Greenland using transplanted seaweed, mussels and sea snails. In addition, passive DGT samplers were installed. After a 9-day deployment period, concentrations of especially Pb, Zn and Fe in the species were all markedly elevated at the monitoring sites closest to the mine. Lead concentrations in all three species and the DGT-Pb results showed a significant linear correlation. Zinc and Fe concentrations were less correlated indicating that the mechanisms for Zn and Fe accumulation in the three species are more complex. The results show that there is still a significant load of metals from the mine and that such buoys can be an adequate method to assess present loads of bioavailable metals. 相似文献