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Author: Sean Christopher Crosby
Publisher:
ISBN:
Category :
Languages : en
Pages : 111
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Book Description
Accurate coastal wave predictions are needed to support nearshore process modeling (transport, erosion) and local risk assessment (flooding, inundation). Small errors in direction or frequency have relatively large impacts to transport, run-up estimates. Nearshore prediction error is often dominated by offshore uncertainties in regional models. Detailed, frequency-direction, spectra are needed offshore to accurately estimate blocking and refraction in sheltered regions, e.g. the Southern California Bight (SBC). Here, nearshore prediction skill using both global wave model predictions and offshore buoy observations in the offshore boundary condition is compared for swell-band wave energy (0.04-0.09Hz). Despite inherent directional ambiguity, offshore buoy observations yield a more accurate boundary condition. Analytical and ah hoc combinations global model predictions and offshore buoy observations are tested and yield worse and marginally improved predictions respectively (as compared to buoy-driven predictions). Coastal regions often contain sheltered nearshore wave observations. Assimilating nearshore observations in regional wave models theoretically will improve regional skill. However, nonlinear wave propagation models (e.g. SWAN, WW3) are difficult to invert. Recent developments employ variational methods, but success in complex real-world environments has yet to be observed. At swell-bands wave energy propagation across narrow shelves (e.g. U.S. West Coast) is dominated by linear processes (refraction, shoaling) and well modeled by self-adjoint ray tracing. Here, a general assimilation framework is developed to estimate physically smooth (time, direction), accurate, offshore boundary conditions from offshore and sheltered buoy observations with global model predictions included as a model prior. Case studies show error reduction at validation (non-assimilated) buoy sites suggesting that assimilation of nearshore observations improves regional skill. Initial results suggest that few (1 offshore, 1-2 nearshore) buoys are needed to sufficiently resolve offshore conditions, which has implications for cost-effective buoy array design. Additionally, buoy sites with significant misfit to assimilated observations identify regions of model error suggesting missing model physics (e.g. diffraction, reflection).
Author: Sean Christopher Crosby
Publisher:
ISBN:
Category :
Languages : en
Pages : 111
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Book Description
Accurate coastal wave predictions are needed to support nearshore process modeling (transport, erosion) and local risk assessment (flooding, inundation). Small errors in direction or frequency have relatively large impacts to transport, run-up estimates. Nearshore prediction error is often dominated by offshore uncertainties in regional models. Detailed, frequency-direction, spectra are needed offshore to accurately estimate blocking and refraction in sheltered regions, e.g. the Southern California Bight (SBC). Here, nearshore prediction skill using both global wave model predictions and offshore buoy observations in the offshore boundary condition is compared for swell-band wave energy (0.04-0.09Hz). Despite inherent directional ambiguity, offshore buoy observations yield a more accurate boundary condition. Analytical and ah hoc combinations global model predictions and offshore buoy observations are tested and yield worse and marginally improved predictions respectively (as compared to buoy-driven predictions). Coastal regions often contain sheltered nearshore wave observations. Assimilating nearshore observations in regional wave models theoretically will improve regional skill. However, nonlinear wave propagation models (e.g. SWAN, WW3) are difficult to invert. Recent developments employ variational methods, but success in complex real-world environments has yet to be observed. At swell-bands wave energy propagation across narrow shelves (e.g. U.S. West Coast) is dominated by linear processes (refraction, shoaling) and well modeled by self-adjoint ray tracing. Here, a general assimilation framework is developed to estimate physically smooth (time, direction), accurate, offshore boundary conditions from offshore and sheltered buoy observations with global model predictions included as a model prior. Case studies show error reduction at validation (non-assimilated) buoy sites suggesting that assimilation of nearshore observations improves regional skill. Initial results suggest that few (1 offshore, 1-2 nearshore) buoys are needed to sufficiently resolve offshore conditions, which has implications for cost-effective buoy array design. Additionally, buoy sites with significant misfit to assimilated observations identify regions of model error suggesting missing model physics (e.g. diffraction, reflection).
Author: Rohini Chandrala
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Accurate wave predictions safeguard maritime operations, coastal communities, and marine ecosystems. Significant wave height, an average height of the highest one-third of the waves recorded during the sampling period, plays a crucial role in analyzing wave conditions and assessing coastal hazards among various wave fields. Forecasting significant wave height for various future timeframes, starting from 0.5 hours ahead, is vital for estimating coastal storm surges, issuing weather warnings, and preventing coastal disasters, especially during imminent large waves. Numerical methods are commonly used for wave forecasting; however, due to their computational intensity, they often require more time. In emergency situations, data-driven models offer faster wave predictions while maintaining accuracy, for shorter timeframes into the future. Data-driven forecasting models often treat data reported by buoys individually and forecast significant wave height based on the historical data of the respective buoy. Models trained on data from multiple buoys might leverage combined insights. However, training a single model on all different buoys may reduce forecasting accuracy when the data is from buoys in different environments. This study proposes a two-step approach to improve significant wave height predictions on a set of Environment and Climate Change Canada (ECCC) buoy data. First, we cluster buoys with similar data, enabling the formation of clusters with similar environmental conditions. Second, we train a global forecasting model on each cluster and predict significant wave height for individual buoys. We evaluate our proposed approach for significant wave height forecasting using data collected by 28 ECCC buoys distributed across the Atlantic, Pacific, and Great Lakes regions of Canada. Our results demonstrate that the clustering-based forecasting models, which leverage the shared patterns and relationships among multiple related buoy data, show competitive performance compared to the data-driven models trained on individual buoy data or universal model trained on all buoy data, in extreme events where wave height exceeds 6 meters.
Author: G. J. Komen
Publisher: Cambridge University Press
ISBN: 0521470471
Category : Science
Languages : en
Pages : 558
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Book Description
A comprehensive introduction and reference prepared by the world's leading ocean wave modellers.
Author: Willard J Pierson
Publisher:
ISBN:
Category : Hydrology
Languages : en
Pages : 312
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Book Description
Author: Madhav L. Khandekar
Publisher: Springer Science & Business Media
ISBN: 1461389526
Category : Science
Languages : en
Pages : 223
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Book Description
This monograph is an attempt to compile the present state of knowledge on ocean wave analysis and prediction. The emphasis of the monograph is on the development of ocean wave analysis and predic tion procedures and their utility for real-time operations and appli cations. Most of the material in the monograph is derived from journal articles, research reports and recent conference proceedings; some of the basic material is extracted from standard text books on physical oceanography and wind waves. Ocean wave analysis and prediction is becoming an important activity in the meteorological and oceanographic services of many countries. The present status of ocean wave prediction may be compar able to the status of numerical weather prediction of the mid-sixties and early seventies when a number of weather prediction models were developed for research purposes, many of which were later put into operational use by meteorological services of several countries. The increased emphasis on sea-state analysis and prediction has created a need for a ready reference material on various ocean wave analysis and modelling techniques and their utility. The present monograph is aimed at fulfilling this need. The monograph should prove useful to the ocean wave modelling community as well as to marine forecasters, coastal engineers and offshore technologists. The monograph could also be used for a senior undergraduate (or a first year graduate) level course in ocean wave modelling and marine meteorology.
Author: Stanislaw Ryszard Massel
Publisher: World Scientific
ISBN: 9814460133
Category : Technology & Engineering
Languages : en
Pages : 690
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Book Description
New Edition: Ocean Surface Waves: Their Physics and Prediction (3rd Edition)The book is an extended and updated edition of the book published in 1996 under the same title (World Scientific, ISBN 9810216866). It contains a very comprehensive and extensive study on surface ocean waves induced by wind, earthquakes and possible landslides and asteroids impacts. The basic mathematical principles, physical description of the observed phenomena, practical forecasting techniques of the various wave parameters and extended application in ocean and coastal engineering, are discussed from the stochastic point of view.All chapters were completely rewritten and supplemented with many new discoveries which were published since the first edition in 1996. In particular, new chapters are added on very interesting and contemporary topics such as: wave breaking mechanisms in deep- and shallow water, freak waves, tsunami, water circulation in porous sea bottom induced by surface waves, and waves propagation through mangrove forests.In terms of numerical modeling, the state of the art of the modern methodology of wave prediction models WAM and SWAN, as well as of the high sophisticated satellite methods of waves measurement and modern methods of signal processing, including wavelets approach and Hilbert Transform approach are presented. The book is supplemented with an extended list of relevant and extended, contemporary bibliography, subject index and author index.
Author: Yongyao Zhao
Publisher:
ISBN:
Category : Marine meteorology
Languages : en
Pages : 58
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Book Description
This report describes the OPC spectral wave forecasting model for the Columbia River Bar, as well as the results of some numerical experiments, on both micro and main frame computers. The model, essentially, calculates the transformation of offshore wave spectra forecasted by the OPC global wave model due to the combined effects of bottom topography and tidal currents in the vicinity of the Columbia River entrance.
Author: Stanislaw R. Massel
Publisher: World Scientific
ISBN: 9789810221096
Category : Science
Languages : en
Pages : 514
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Book Description
This book is intended as a handbook for professionals and researchers in the areas of Physical Oceanography, Ocean and Coastal Engineering and as a text for graduate students in these fields. It presents a comprehensive study on surface ocean waves induced by wind, including basic mathematical principles, physical description of the observed phenomena, practical forecasting techniques of various wave parameters and applications in ocean and coastal engineering, all from the probabilistic and spectral points of view. The book commences with a description of mechanisms of surface wave generation by wind and its modern modeling techniques. The stochastic and probabilistic terminology is introduced and the basic statistical and spectral properties of ocean waves are developed and discussed in detail. The bulk of material deals with the prediction techniques for waves in deep and coastal waters for simple and complex ocean basins and complex bathymetry. The various prediction methods, currently used in oceanography and ocean engineering, are described and the examples of practical calculations illustrate the basic text. An appendix provides a description of the modern methods of wave measurement, including the remote sensing techniques. Also the wave simulation methods and random data analysis techniques are discussed. In the book a lot of discoveries of the Russian and East European scientists, largely unknown in the Western literature due to the language barrier, are referred to.
Author: Karen M. Wingeart
Publisher:
ISBN:
Category : Buoys
Languages : en
Pages : 57
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Book Description
Global wave predictions produced at two U.S. forecasting centers, Fleet Numerical Meteorology and Oceanography Center (FNMOC) and the National Centers for Environmental Prediction (NCEP) are evaluated with spectral buoy measurements. In this study, the fidelity of frequency-directional spectra predicted by WAM and WAVEWATCH III at the operational centers is examined with data from 3-meter discus and 6-meter nomad buoys operated by the National Data Buoy Center in the Atlantic and Pacific Oceans and Datawell Directional Waverider buoys deployed along the California coast by the Scripps Institution of Oceanography Coastal Data information Program. Only buoys located in deep water are used in the comparisons. Model nowcasts of frequency spectra and mean wave directions are compared to buoy measurements over a six-month period from 1 October 2000 to 31 March 2001. At the Pacific buoy locations, individual swell events were identified in the spectra from the three models and the buoy data, Predicted and observed swell frequencies and arrival directions are compared at the Pacific buoy locations, as well as the total energy transported past the buoy over the duration of each individual event. At all buoy locations, predicted and observed wave energy fluxes integrated over fixed frequency ranges are compared. All three models yield reliable nowcasts of swell arrivals at the buoy locations. In most cases, the models under-predict the energy measured by the buoys. WAVEWATCH III better resolves low-frequency swells than WAM, possibly owing to a superior numerical scheme. Swell predictions at NCEP forced with AVN winds are more accurate that those at FNMOC forced with NOGAPS winds.
Author: Eric P. Chassignet
Publisher: Springer Science & Business Media
ISBN: 1402040288
Category : Science
Languages : en
Pages : 573
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Book Description
This volume covers a wide range of topics and summarizes our present knowledge in ocean modeling, ocean observing systems, and data assimilation. The Global Ocean Data Assimilation Experiment (GODAE) provides a framework for these efforts: a global system of observations, communications, modeling, and assimilation that will deliver regular, comprehensive information on the state of the oceans, engendering wide utility and availability for maximum benefit to the community.
