@article{26,
  keywords = {Air{\textendash}sea fluxes, Atmosphere{\textendash}ocean{\textendash}wave coupled model, Drag parametrization, Extreme surface wind speeds, Midlatitude cyclones},
  author = {Emanuele Gentile and Suzanne Gray and Janet Barlow and Huw Lewis and John Edwards},
  title = {The Impact of Atmosphere{\textendash}Ocean{\textendash}Wave Coupling on the Near-Surface Wind Speed in Forecasts of Extratropical Cyclones},
  abstract = {<p>Accurate modelling of air{\textendash}sea surface exchanges is crucial for reliable extreme surface wind-speed forecasts. While atmosphere-only weather forecast models represent ocean and wave effects through sea-state independent parametrizations, coupled multi-model systems capture sea-state dynamics by integrating feedbacks between the atmosphere, ocean and wave model components. Here, we investigate the sensitivity of extreme surface wind speeds to air{\textendash}sea exchanges at the kilometre scale using coupled and uncoupled configurations of the Met Office{\textquoteright}s UK Regional Coupled Environmental Prediction system. The case period includes the passage of extra-tropical cyclones Helen, Ali, and Bronagh, which brought maximum gusts of 36\&nbsp;m\&nbsp;s-1 over the UK. Compared with the atmosphere-only results, coupling to the ocean decreases the domain-average sea-surface temperature by up to 0.5\&nbsp;K. Inclusion of coupling to waves reduce the 98th percentile 10-m wind speed by up to 2\&nbsp;m\&nbsp;s-1 as young, growing wind waves reduce the wind speed by increasing the sea-surface aerodynamic roughness. Impacts on gusts are more modest, with local reductions of up to 1\&nbsp;m\&nbsp;s-1, due to enhanced boundary-layer turbulence which partially offsets air{\textendash}sea momentum transfer. Using a new drag parametrization based on the Coupled Ocean{\textendash}Atmosphere Response Experiment\&nbsp;4.0 parametrization, with a cap on the neutral drag coefficient and reduction for wind speeds exceeding 27\&nbsp;m\&nbsp;s-1, the atmosphere-only model achieves equivalent impacts on 10-m wind speeds and gusts as from coupling to waves. Overall, the new drag parametrization achieves the same 20\% improvement in forecast 10-m wind-speed skill as coupling to waves, with the advantage of saving the computational cost of the ocean and wave models.</p>
},
  year = {2021},
  journal = {Boundary-Layer Meteorology},
  volume = {180},
  pages = {105-129},
  month = {07/2021},
  url = {https://link.springer.com/article/10.1007/s10546-021-00614-4},
  doi = {10.1007/s10546-021-00614-4},
}