Abstract. To improve high-resolution numerical environmental prediction, it is essential to represent ocean-atmosphere interactions properly, which is not the case in current operational regional forecasting systems used in Western Europe. The objective of this paper is to present a new forecast-oriented coupled ocean-atmosphere system and its evaluation. This system uses the state-of-the-art numerical models AROME (cy43t2) and NEMO (v3.6) with a horizontal resolution of 2.5 km. The OASIS coupler (OASIS3MCT-4.0), implemented in the SurfEX surface scheme and in NEMO, is used to perform the communications between models. The evaluation of this system is carried out using 7-day simulations from 12 to 19 October 2018, characterised by extreme weather events (storms and heavy precipitation event) in the area of interest. Comparisons with in-situ and L3 satellite observations show that the fully coupled simulation reproduces quantitatively well the spatial and temporal evolution of the sea surface temperature and 10 m wind speed. Sensitivity analysis to OA coupling show that the use of an interactive and high resolution SST, in contrast to actual NWP where SST is persistent and at low resolution, modifies the atmospheric circulation and the location of heavy precipitation. When compared to the operational-like ocean forecast, simulated oceanic fields show a large sensitivity to coupling. Forced ocean simulations highlight that this sensitivity is mainly controlled by the change in the atmospheric model used to drive NEMO (AROME vs. ECMWF IFS operational forecast). The oceanic boundary layer depths can vary by more than 40%. This impact is amplified by the interactive coupling and is attributed to positive feedback between sea surface cooling and evaporation.

中文翻译：

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开发面向西欧的以预报为导向的公里分辨率海洋-大气耦合系统和对恶劣天气情况的评估

摘要。为了提高高分辨率数值环境预测，必须正确表示海洋-大气相互作用，而西欧目前使用的业务区域预测系统并非如此。本文的目的是提出一种新的面向预报的海洋-大气耦合系统及其评估。该系统使用最先进的数值模型 AROME (cy43t2) 和 NEMO (v3.6)，水平分辨率为 2.5 公里。在 SurfEX 表面方案和 NEMO 中实现的 OASIS 耦合器 (OASIS3MCT-4.0) 用于执行模型之间的通信。该系统的评估是使用 2018 年 10 月 12 日至 19 日的 7 天模拟进行的，其特征是感兴趣区域内的极端天气事件（风暴和强降水事件）。与原位和 L3 卫星观测的比较表明，全耦合模拟在数量上很好地再现了海面温度和 10 m 风速的时空演变。对 OA 耦合的敏感性分析表明，与 SST 持续存在且分辨率低的实际 NWP 相比，使用交互式和高分辨率 SST 会改变大气环流和强降水的位置。与类似操作的海洋预测相比，模拟的海洋场对耦合表现出很大的敏感性。强制海洋模拟强调，这种敏感性主要受用于驱动 NEMO 的大气模型变化（AROME 与 ECMWF IFS 业务预测）的控制。海洋边界层深度的变化可能超过 40%。