Accurate modelling of air–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–sea exchanges at the kilometre scale using coupled and uncoupled configurations of the Met Office’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 m 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 K. Inclusion of coupling to waves reduce the 98th percentile 10-m wind speed by up to 2 m 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 m s\(^{-1}\), due to enhanced boundary-layer turbulence which partially offsets air–sea momentum transfer. Using a new drag parametrization based on the Coupled Ocean–Atmosphere Response Experiment 4.0 parametrization, with a cap on the neutral drag coefficient and reduction for wind speeds exceeding 27 m 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.

准确的海-海表面交换模型对可靠的极端地表风速预报至关重要。纯大气层天气预报模型通过独立于海状态的参数表示海洋和波浪效应，而耦合的多模型系统则通过整合大气，海洋和波浪模型组件之间的反馈来捕获海态动态。在这里，我们使用气象局英国区域耦合环境预测系统的耦合和非耦合配置，研究了极地地面风速对公里尺度海空交换的敏感性。病例期包括温带气旋Helen，Ali和Bronagh的通过，它们带来的最大阵风为36 m s \（^ {-1} \）在英国。与仅大气的结果相比，与海洋的耦合将使区域平均海面温度降低多达0.5K。包括与波的耦合会使98％的10-m风速降低高达2 m s \（^ { -1} \）时，不断增长的风波会通过增加海面空气动力学粗糙度来降低风速。由于增强的边界层湍流部分抵消了海-海动量传递，因此对阵风的影响较为温和，局部减少高达1 m s \（^ {-1} \）。使用基于“海-气耦合反应实验4.0”参数化的新阻力参数化，对中性阻力系数设置上限，并在风速超过27 m s时减小\（^ {-1} \），纯大气层模型对10毫米风速和阵风的影响与从耦合到波浪的影响相同。总体而言，新的阻力参数化技术在预测10米风速时的技巧与与波浪耦合时相同，提高了20％，其优点是节省了海洋和波浪模型的计算成本。