scholarly journals Assessing the Performance of the Dissipation Parameterizations in WAVEWATCH III Using Collocated Altimetry Data

2009 ◽  
Vol 39 (11) ◽  
pp. 2800-2819 ◽  
Author(s):  
Georgia D. Kalantzi ◽  
Christine Gommenginger ◽  
Meric Srokosz
Keyword(s):  
Wave Height ◽  
Wave Breaking ◽  
Source Term ◽  
Wave Spectrum ◽  
Wave Model ◽  
North Indian Ocean ◽  
Altimeter Data ◽  
Wave Direction ◽  
Wavewatch Iii ◽  
The North

Abstract Wave-breaking dissipation is one of the least understood processes implemented in contemporary wave models. Significant effort has been put in its parameterization, but it has not proven to be totally satisfactory, either theoretically or practically. In this work, the WAVEWATCH III (version 2.22; Tolman) wave model is used to evaluate the two wind input/dissipation source term packages that it includes: (i) Wave Model (WAM) cycle 3 (WAMDIG) and (ii) Tolman and Chalikov. Global model outputs were obtained under the same wind forcing for the two dissipation formulations and were collocated in space and time in the north Indian Ocean with Ocean Topography Experiment (TOPEX) altimeter data. The performance of the model was assessed by evaluating the statistical behavior of the collocated datasets. The parameters examined were significant wave height, wind speed, wind direction, wave direction, wave height for fully developed seas, and energy loss due to wave breaking. From the results, the behavior of the input/dissipation formulations in specific wind and wave conditions was identified; that is, the results give insight to the way the two source term packages “work” and how they respond to local wind sea or swell. Specifically, both of the packages were unable to perform adequately during a season when the area can be mostly affected by swell. However, the results confirmed that the examination of only integral spectral wave parameters does not give information on the inherent physical characteristics of the formulations. Further study, on the basis of point spectra, is necessary to examine the formulations’ performance across the wave spectrum.

scholarly journals Marine Wind and Wave Height Trends at Different ERA-Interim Forecast Ranges

2015 ◽  
Vol 28 (2) ◽  
pp. 819-837 ◽  
Author(s):  
Ole Johan Aarnes ◽  
Saleh Abdalla ◽  
Jean-Raymond Bidlot ◽  
Øyvind Breivik
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
North Atlantic ◽  
Wave Model ◽  
Altimeter Data ◽  
The North ◽  
The Impact ◽  
Global Reanalysis ◽  
Made In

Abstract Trends in marine wind speed and significant wave height are investigated using the global reanalysis ERA-Interim over the period 1979–2012, based on monthly-mean and monthly-maximum data. Besides the traditional reanalysis, the authors include trends obtained at different forecast range, available up to 10 days ahead. Any model biases that are corrected differently over time are likely to introduce spurious trends of variable magnitude. However, at increased forecast range the model tends to relax, being less affected by assimilation. Still, there is a trade-off between removing the impact of data assimilation at longer forecast range and getting a lower level of uncertainty in the predictions at shorter forecast range. Because of the sheer amount of assimilations made in ERA-Interim, directly and indirectly affecting the data, it is difficult, if not impossible, to distinguish effects imposed by all updates. Here, special emphasis is put on the introduction of wave altimeter data in August 1991, the only type of data directly affecting the wave field. From this, it is shown that areas of higher model bias introduce quite different trends depending on forecast range, most apparent in the North Atlantic and eastern tropical Pacific. Results are compared with 23 in situ measurements, Envisat altimeter winds, and two stand-alone ECMWF operational wave model (EC-WAM) runs with and without wave altimeter assimilation. Here, the 48-h forecast is suggested to be a better candidate for trend estimates of wave height, mainly due to the step change imposed by altimeter observations. Even though wind speed seems less affected by undesirable step changes, the authors believe that the 24–48-h forecast more effectively filters out any unwanted effects.

Implementing New Nonlinear Term in Third Generation Wave Models

2014 ◽  
Author(s):  
Odin Gramstad ◽  
Alexander Babanin
Keyword(s):  
Kinetic Equation ◽  
Spread Spectrum ◽  
Time Scale ◽  
Source Term ◽  
Wave Spectrum ◽  
Wave Model ◽  
Third Generation ◽  
Spectral Evolution ◽  
Linear Interaction ◽  
Wavewatch Iii

The non-linear interaction term is one of the three key source functions in every third-generation spectral wave model. An update of physics of this term is discussed. The standard statistical/phase-averaged description of the nonlinear transfer of energy in the wave spectrum (wave-turbulence) is based on Hasselmann’s kinetic equation [1]. In the derivation of the kinetic equation (KE) it is assumed that the evolution takes place on the slow O(ε−4) time scale, where ε is the wave steepness. This excludes the effects of near-resonant quartet interactions that may lead to spectral evolution on the ‘fast’ O(ε−2) time scale. Generalizations of the KE (GKE) that enable description of spectral evolution on the O(ε−2) time scale [2–4] are discussed. The GKE, first solved numerically in [4], is implemented as a source term in the third generation wave model WAVEWATCH-III. The new source term (GKE) is tested and compared to the other nonlinear-interaction source terms in WAVEWATCH-III; the full KE (WRT method) and the approximate DIA method. It is shown that the GKE gives similar results to the KE in the case of a relatively broad banded and directional spread spectrum, while it shows somewhat larger difference in the case of a more narrow banded spectrum with narrower directional distribution. We suggest that the GKE may be a suitable replacement to the KE in situations where ‘fast’ spectral evolution takes place.

scholarly journals Accuracy Evaluation of CFOSAT SWIM L2 Products Based on NDBC Buoy and Jason-3 Altimeter Data

2021 ◽  
Vol 13 (5) ◽  
pp. 887
Author(s):  
Guozhou Liang ◽  
Jungang Yang ◽  
Jichao Wang
Keyword(s):  
Wave Height ◽  
Wave Spectrum ◽  
Data Accuracy ◽  
Ocean Wave ◽  
Global Ocean ◽  
Altimeter Data ◽  
Accuracy Evaluation ◽  
Wave Direction ◽  
Dominant Wave ◽  
Better Than

Chinese-French Oceanography Satellite (CFOSAT), the first satellite which can observe global ocean wave and wind synchronously, was successfully launched On 29 October 2018. The CFOSAT carries SWIM that can observe ocean wave on a global scale. Based on National Data Buoy Center (NDBC) buoys and Jason-3 altimeter data, this study evaluated the accuracy of L2 level products of CFOSAT SWIM from August 2019 to September 2020. The results show that the accuracy of the nadir Significant Wave Height (SWH) data of the SWIM wave spectrometer is good. Compared with the data of the NDBC buoys and Jason-3 altimeter, the RMSE of the nadir box SWH were 0.39 and 0.21 m, respectively. The variation trend of SWH were first increasing and then decreasing with the increasing of the wave height. The precision of off-nadir wave spectrum SWH is not better than nadir box SWH data. Accuracy was evaluated for off-nadir data from August 2019 to June 2020 and after June 2020, respectively. After linear regression correction, the accuracy of off-nadir wave spectrum SWH was improved. The data accuracy evaluation and comparison of different time period showed that the off-nadir wave spectrum SWH accuracy was improved after the data version was updated in June 2020, especially for 6° and 8° wave spectrum. The precision of off-nadir wave spectrum SWH decreases with the increasing of wave height. The accuracy of the dominant wave direction of each wave spectrum is also not very good, and the accuracy of the dominant wave direction of 10° wave spectrum is slightly better than the others. In general, the accuracy of SWIM nadir beam SWH data reaches the high data accuracy of traditional altimeter, while the accuracy of off-nadir wave spectrum SWH is less than that of nadir beam SWH data. The off-nadir SWH data accuracy after June 2020 has been greatly improved.

scholarly journals WAM and WAVEWATCH-III intercomparison studies in the North Indian Ocean using Oceansat-2 Scatterometer winds

2019 ◽  
Vol 9 ◽  
pp. 251601921986656 ◽  
Author(s):  
J Swain ◽  
PA Umesh ◽  
AN Balchand
Keyword(s):  
Indian Ocean ◽  
Wave Height ◽  
Statistical Error ◽  
North Indian Ocean ◽  
Wavewatch Iii ◽  
The North ◽  
Wave Measurements ◽  
Mean Wave Period ◽  
The Individual

This paper presents the intercomparison of wave hindcasts using the third-generation models WAM and WAVEWATCH-III for the North Indian Ocean over 1° × 1° (latitude × longitude) grid resolutions, which reveals the first assessment of their relative performance through intercomparison of the model results. Hindcast wave parameters such as significant wave height, mean wave period, and swell wave height obtained from the simulations using Oceansat-2 scatterometer winds are analyzed to understand the quality and variability associated with the individual model outputs in the Indian Ocean. WAM and WAVEWATCH-III intercomparison studies are carried out for four different cases (January and June 2010, and January and June 2011). A comparative study of the relative performances of these two models is evaluated through extensive and robust statistical error analysis. Based on both qualitative and quantitative assessment of the model results, this study clearly indicates that both WAM and WAVEWATCH-III performed well in the common model domain using Oceansat-2 scatterometer winds, and they can be confidently used for long-term hindcasting in the North Indian Ocean, which will be very useful for most of the user community dealing with various coastal/offshore activities. The study also suggests that it would be preferable to consider available long-term wave measurements both in deep and coastal waters of the North Indian Ocean to validate and intercompare WAM and WAVEWATCH-III further.

Performance of WAVEWATCH-III and SWAN Models in the North Sea

2018 ◽  
Author(s):  
Sonia Ponce de León ◽  
J. Bettencourt ◽  
G. Ph. Van Vledder ◽  
P. Doohan ◽  
C. Higgins ◽  
...  
Keyword(s):  
North Sea ◽  
Wave Spectrum ◽  
Point Of View ◽  
Wave Direction ◽  
Ocean Engineering ◽  
Wind Fields ◽  
Peak Period ◽  
Wavewatch Iii ◽  
The North ◽  
The North Sea

This paper presents the hindcast of the winter of 2013 in the North Sea using two wave models: WAVEWATCH-III (WW3) and SWAN. The performance of the WW3 and SWAN models was assessed for this winter, when successive storms hit the hindcast area in a short time period, and examined in terms of the averaged wave parameters (Hs, peak period and wave direction) and the power wave spectrum. The assessment was made from an operational point of view. Possible effects of the accuracy of the wind fields, the physics chosen in each model and numerical settings are discussed. We elaborate on efficiency, accuracy and grid issues for both models, aiming to provide guidelines for ocean engineering wave forecasts.

Sensitivity analysis of dissipation parameterizations in the WAVEWATCH III spectral wave model using the ST6 source term packages for Ireland Coast.

2020 ◽  
Author(s):  
Leandro Fernández ◽  
Clement Calvino ◽  
Frederic Dias
Keyword(s):  
Sensitivity Analysis ◽  
North Atlantic ◽  
Source Term ◽  
Wave Model ◽  
Long Distance ◽  
Wavewatch Iii ◽  
North East ◽  
The North ◽  
Spectral Wave Model ◽  
The North Atlantic

<p>The research we perform has important engineering applications since a lot of marine activities and offshore engineering activities are in shallow water areas where phenomena like bottom and white-capping dissipation and wind growth take place. The physical parametrization of such forcing/dissipation has become an important issue in the improvement of the performance of models in order to provide accurate sea-state information. In this regard, we perform a sensitivity analysis of dissipation parameterizations in the third-generation spectral wave model WAVEWATCH III using the ST6 source term packages, proposed by Zieger-Babanin 2015, to describe wind generation and dissipation due to white-capping and bottom friction.</p><p>A system of nested grids is used to model long distance swells generated in the North Atlantic Ocean and propagating all the way to the west coast of Ireland. We used a 30-minute coarse resolution for the North Atlantic grid, a 6-minute intermediate resolution for the North-East Atlantic, and a 3-minute fine resolution in coastal areas closer to Ireland.</p><p>The sensitivity analysis in the parameterization is based on the effect of the model performance by varying the adjustable parameters in the wind input source, swell dissipation in terms of the interaction of waves with oceanic turbulence and the drag coefficient to potentially eliminate a bias in the wind field. The results of the model for the coast of Ireland are discussed in terms of various parametrization schemes.</p>

scholarly journals Operability Guidelines For Product Tanker In Heavy Weather In The Adriatic Sea

2014 ◽  
Vol 21 (1) ◽  
pp. 95-106
Author(s):  
Luka Mudronja ◽  
Marko Katalinić ◽  
Rino Bošnjak ◽  
Pero Vidan ◽  
Joško Parunov
Keyword(s):  
Wave Height ◽  
Adriatic Sea ◽  
Wave Spectrum ◽  
Extreme Weather ◽  
The South ◽  
Sea State ◽  
M Wave ◽  
The North ◽  
Limiting Values ◽  
Deck Wetness

AbstractThis paper presents operability guidelines for seafarers on a product tanker which navigates in the Adriatic Sea during heavy weather. Tanker route starts from the Otranto strait in the south to the island Krk in the north of Adriatic Sea. Heavy weather is caused by south wind called jugo (blowing from E-SE to SS-E, sirocco family). Operability guidelines are given based on an operability criteria platform for presenting ship seakeeping characteristics. Operability criteria considered in this paper are propeller emergence, deck wetness and bow acceleration of a product tanker. Limiting values of mentioned criteria determine sustainable speed. Heavy weather is described by extreme sea state of 7.5 m wave height. Wave spectrum used in this paper is Tabain spectrum which is developed specifically for Adriatic Sea. Seafarer's approach of decisions making in extreme weather is also shown and servers as a guideline for further research of the authors.

scholarly journals Numerical Investigation of Hydrodynamics and Cohesive Sediment Transport in Cua Lo and Cua Hoi Estuaries, Vietnam

2021 ◽  
Vol 9 (11) ◽  
pp. 1258
Author(s):  
Viet Thanh Nguyen ◽  
Minh Tuan Vu ◽  
Chi Zhang
Keyword(s):  
Sediment Transport ◽  
Great Influence ◽  
Wave Model ◽  
Sediment Concentration ◽  
Wave Climate ◽  
Cohesive Sediment ◽  
Wave Direction ◽  
The South ◽  
The North ◽  
Cohesive Sediment Transport

Two-dimensional models of large spatial domain including Cua Lo and Cua Hoi estuaries in Nghe An province, Vietnam, were established, calibrated, and verified with the observed data of tidal level, wave height, wave period, wave direction, and suspended sediment concentration. The model was then applied to investigate the hydrodynamics, cohesive sediment transport, and the morphodynamics feedbacks between two estuaries. Results reveal opposite patterns of nearshore currents affected by monsoons, which flow from the north to the south during the northeast (NE) monsoon and from the south to the north during the southeast (SE) monsoon. The spectral wave model results indicate that wave climate is the main control of the sediment transport in the study area. In the NE monsoon, sediment from Cua Lo port transported to the south generates the sand bar in the northern bank of the Cua Hoi estuary, while sediment from Cua Hoi cannot be carried to the Cua Lo estuary due to the presence of Hon Ngu Island and Lan Chau headland. As a result, the longshore sediment transport from the Cua Hoi estuary to the Cua Lo estuary is reduced and interrupted. The growth and degradation of the sand bars at the Cua Hoi estuary have a great influence on the stability of the navigation channel to Ben Thuy port as well as flood drainage of Lam River.

Assessing Climate Change in the North Atlantic Wave Regimes

2020 ◽  
Author(s):  
M. Bernardino ◽  
M. Gonçalves ◽  
C. Guedes Soares
Keyword(s):  
System Integration ◽  
Wave Model ◽  
Offshore Structures ◽  
Future Climate ◽  
Wave Direction ◽  
Peak Period ◽  
Significant Wave ◽  
The North ◽  
Wave Heights ◽  
Mean Wave Period

Abstract An improved understanding of the present and future marine climatology is necessary for numerous activities, such as operation of offshore structures, optimization of ship routes and the evaluation of wave energy resources. To produce global wave information, the WW3 wave model was forced with wind and ice-cover data from an RCP8.5 EC-Earth system integration for two 30-year time slices. The first covering the periods from 1980 to 2009 represents the present climate and the second, covering the periods from 2070–2099, represents the climate in the end of the 21st century. Descriptive statistics of wind and wave parameters are obtained for different 30-year time slices. Regarding wind, magnitude and direction will be used. For wave, significant wave height (of total sea and swell), mean wave period, peak period, mean wave direction and energy will be investigated. Changes from present to future climate are evaluated, regarding both mean and extreme events. Maps of the theses statistics are presented. The long-term monthly joint distribution of significant wave heights and peak periods is generated. Changes from present to future climate are assessed, comparing the statistics between time slices.

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