Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic Observations

Abstract The fractional or percentage whitecap coverage of the ocean surface (W) is often parameterized in terms of wind speed. Data sets of W typically show order of magnitude scatter at a given wind speed value due to sea state variability. Here we compare modeled values of W to measured W values...

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Main Authors: A. H. Callaghan, J.‐R. Bidlot, G. deLeeuw, C. D. O’Dowd
Format: Article
Language:English
Published: Wiley 2025-02-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1029/2024GL112996
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author A. H. Callaghan
J.‐R. Bidlot
G. deLeeuw
C. D. O’Dowd
author_facet A. H. Callaghan
J.‐R. Bidlot
G. deLeeuw
C. D. O’Dowd
author_sort A. H. Callaghan
collection DOAJ
description Abstract The fractional or percentage whitecap coverage of the ocean surface (W) is often parameterized in terms of wind speed. Data sets of W typically show order of magnitude scatter at a given wind speed value due to sea state variability. Here we compare modeled values of W to measured W values from the North Atlantic Ocean. The modeled W is forced by the spectrally integrated whitecap dissipation source function in the European Center for Medium‐Range Weather Forecasts spectral wave model, ecWAM. Without tuning, best agreement is found for mature sea states, with an average modeled to measured W ratio of 0.87. This ratio approaches unity with the introduction of a dissipation rate threshold value and an explicit wave‐age dependence. The study suggests that accurate estimates of W can be routinely produced by ecWAM and opens new opportunities to model bubble‐mediated fluxes of CO2 and sea spray aerosol with ecWAM.
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series Geophysical Research Letters
spelling doaj-art-2d5c93ae3dbd4d7595a73e00b1d679fa2025-08-20T02:57:05ZengWileyGeophysical Research Letters0094-82761944-80072025-02-01523n/an/a10.1029/2024GL112996Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic ObservationsA. H. Callaghan0J.‐R. Bidlot1G. deLeeuw2C. D. O’Dowd3Department of Civil and Environmental Engineering Imperial College London South Kensington UKECMWF Reading UKRoyal Netherlands Meteorological Institute (KNMI) R & D Satellite Observations De Bilt The NetherlandsSchool of Natural Sciences Ryan Institute Centre for Climate and Air Pollution Studies University of Galway Galway IrelandAbstract The fractional or percentage whitecap coverage of the ocean surface (W) is often parameterized in terms of wind speed. Data sets of W typically show order of magnitude scatter at a given wind speed value due to sea state variability. Here we compare modeled values of W to measured W values from the North Atlantic Ocean. The modeled W is forced by the spectrally integrated whitecap dissipation source function in the European Center for Medium‐Range Weather Forecasts spectral wave model, ecWAM. Without tuning, best agreement is found for mature sea states, with an average modeled to measured W ratio of 0.87. This ratio approaches unity with the introduction of a dissipation rate threshold value and an explicit wave‐age dependence. The study suggests that accurate estimates of W can be routinely produced by ecWAM and opens new opportunities to model bubble‐mediated fluxes of CO2 and sea spray aerosol with ecWAM.https://doi.org/10.1029/2024GL112996whitecap coveragespectral wave modelecWAMenergy dissipationwave breakingbubbles
spellingShingle A. H. Callaghan
J.‐R. Bidlot
G. deLeeuw
C. D. O’Dowd
Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic Observations
Geophysical Research Letters
whitecap coverage
spectral wave model
ecWAM
energy dissipation
wave breaking
bubbles
title Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic Observations
title_full Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic Observations
title_fullStr Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic Observations
title_full_unstemmed Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic Observations
title_short Comparing Estimates of Whitecap Coverage From a Spectral Wave Model With Oceanic Observations
title_sort comparing estimates of whitecap coverage from a spectral wave model with oceanic observations
topic whitecap coverage
spectral wave model
ecWAM
energy dissipation
wave breaking
bubbles
url https://doi.org/10.1029/2024GL112996
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AT jrbidlot comparingestimatesofwhitecapcoveragefromaspectralwavemodelwithoceanicobservations
AT gdeleeuw comparingestimatesofwhitecapcoveragefromaspectralwavemodelwithoceanicobservations
AT cdodowd comparingestimatesofwhitecapcoveragefromaspectralwavemodelwithoceanicobservations