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Beyond significant wave height: A new approach for validating spectral wave models

Beyond significant wave height: A new approach for validating spectral wave models
Beyond significant wave height: A new approach for validating spectral wave models
Wave data are required in many engineering applications. At locations where measured records are not available or are too short for design purposes, estimates of wave properties from numerical wave models are often used to characterise the expected wave climate. Typically, model predictions are validated against observations of the sea-state parameters, such as significant wave height, peak wave period, mean wave period and mean wave direction. However, while agreement between observed and predicted sea-state parameters can be good, in some cases the measured and predicted wave spectra can diverge significantly. In these circumstances, simple sea state parameters alone are not sufficient to describe the range of wave conditions that could arise at a given site. In this paper we present a new, alternative approach for assessing wave model performance by applying new parameterisation to the frequency wave spectrum. Seven parameters (significant wave height, peak frequency, peak energy density, squared Euclidean distance, skewness, kurtosis and mean width deviation) are used to better define the characteristics of unimodal wave spectra. Sensitivity tests are undertaken to analyse the performance and sensitivity of these parameters in identifying differences between observed and predicted wave spectra, using a range of idealised JONSWAP wave spectra. We demonstrate that comparing multiple parameters is a better method to distinguish differences between spectra than the results obtained using individual parameters in isolation. As such, application of two-dimensional validation matrices are proposed to provide a better, qualitative overview of the goodness of fit between observed and predicted wave spectra. The advantages of the new approach are demonstrated through validation of a hindcast spectral wave model at Hastings, southeast England. We believe that we have achieved our purpose here to start a discussion on alternative validation techniques that could be enhanced in the future.
Wave spectrum, Validation, Wave model, UK
0378-3839
11-25
Dabbi, Edgar Peter
fcc6210a-f3f4-4470-93ed-8a04626b3a5d
Haigh, Ivan D.
945ff20a-589c-47b7-b06f-61804367eb2d
Lambkin, David
bdc538a1-76f1-46ee-8be5-b1fc7de61367
Hernon, Jamie
87f67639-0118-4b3e-b835-ffa81ca60dbf
Williams, Jon J.
8d4fa85f-eb90-47ca-8115-c34793fad602
Nicholls, Robert J.
4ce1e355-cc5d-4702-8124-820932c57076
Dabbi, Edgar Peter
fcc6210a-f3f4-4470-93ed-8a04626b3a5d
Haigh, Ivan D.
945ff20a-589c-47b7-b06f-61804367eb2d
Lambkin, David
bdc538a1-76f1-46ee-8be5-b1fc7de61367
Hernon, Jamie
87f67639-0118-4b3e-b835-ffa81ca60dbf
Williams, Jon J.
8d4fa85f-eb90-47ca-8115-c34793fad602
Nicholls, Robert J.
4ce1e355-cc5d-4702-8124-820932c57076

Dabbi, Edgar Peter, Haigh, Ivan D., Lambkin, David, Hernon, Jamie, Williams, Jon J. and Nicholls, Robert J. (2015) Beyond significant wave height: A new approach for validating spectral wave models. Coastal Engineering, 100, 11-25. (doi:10.1016/j.coastaleng.2015.03.007).

Record type: Article

Abstract

Wave data are required in many engineering applications. At locations where measured records are not available or are too short for design purposes, estimates of wave properties from numerical wave models are often used to characterise the expected wave climate. Typically, model predictions are validated against observations of the sea-state parameters, such as significant wave height, peak wave period, mean wave period and mean wave direction. However, while agreement between observed and predicted sea-state parameters can be good, in some cases the measured and predicted wave spectra can diverge significantly. In these circumstances, simple sea state parameters alone are not sufficient to describe the range of wave conditions that could arise at a given site. In this paper we present a new, alternative approach for assessing wave model performance by applying new parameterisation to the frequency wave spectrum. Seven parameters (significant wave height, peak frequency, peak energy density, squared Euclidean distance, skewness, kurtosis and mean width deviation) are used to better define the characteristics of unimodal wave spectra. Sensitivity tests are undertaken to analyse the performance and sensitivity of these parameters in identifying differences between observed and predicted wave spectra, using a range of idealised JONSWAP wave spectra. We demonstrate that comparing multiple parameters is a better method to distinguish differences between spectra than the results obtained using individual parameters in isolation. As such, application of two-dimensional validation matrices are proposed to provide a better, qualitative overview of the goodness of fit between observed and predicted wave spectra. The advantages of the new approach are demonstrated through validation of a hindcast spectral wave model at Hastings, southeast England. We believe that we have achieved our purpose here to start a discussion on alternative validation techniques that could be enhanced in the future.

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More information

Published date: June 2015
Keywords: Wave spectrum, Validation, Wave model, UK
Organisations: Physical Oceanography, Civil Maritime & Env. Eng & Sci Unit

Identifiers

Local EPrints ID: 380105
URI: http://eprints.soton.ac.uk/id/eprint/380105
ISSN: 0378-3839
PURE UUID: db1c30a6-d245-43bc-87ff-03d6a7343399
ORCID for Ivan D. Haigh: ORCID iD orcid.org/0000-0002-9722-3061
ORCID for Robert J. Nicholls: ORCID iD orcid.org/0000-0002-9715-1109

Catalogue record

Date deposited: 05 Aug 2015 13:13
Last modified: 15 Mar 2024 03:26

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Contributors

Author: Edgar Peter Dabbi
Author: Ivan D. Haigh ORCID iD
Author: David Lambkin
Author: Jamie Hernon
Author: Jon J. Williams

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