Strong winds in a coupled wave–atmosphere model during a North Atlantic storm event: evaluation against observations

Strong winds may be biased in atmospheric models. Here the European Centre for Medium‐range Weather Forecasts (ECMWF) coupled wave–atmosphere model is used (i) to evaluate strong winds against observations, and (ii) to test how alternative wind stress parametrizations could lead to a more accurate model. For the period of storms Kaat and Lilli (23–27 January 2014), we compared simulated winds with in situ – moored buoys and platforms – and satellite observations available from the North Atlantic. Five wind stress parametrizations were evaluated. The first result is that moderate simulated winds (5–20 m s−1) match with all observations. However, for strong winds (above 20 m s−1), mean differences appear, as much as −7 m s−1 at 30 m s−1. Significant differences also exist between observations, with buoys and Advanced Scatterometer ASCAT‐KNMI generally showing lower wind speeds than the platforms and other remote‐sensing data used in this study (AMSR2, ASCAT‐RSS, WindSat, SMOS and JASON‐2). Buoy and ASCAT‐KNMI winds are likely to underestimate the real wind speed. It is difficult to conclude which dataset should be used as a reference. The second result is that common wave‐age dependent parametrizations produce unrealistic drags and are not appropriate for coupling, whereas a newly empirically adjusted Charnock parametrization leads to higher winds compared to the default ECMWF parametrization. This proposed new parametrization may lead to more accurate results in an operational context. Strong winds may be biased in atmospheric models. Here the ECMWF coupled wave–atmosphere model is used to (i) evaluate strong winds against observations, and (ii) test how alternative wind stress parametrizations could lead to a more accurate model. The proposed new parametrization could yield more accurate results in an operational context.