Mineral dust, the most abundant atmospheric aerosol by mass, interacts with radiation directly and alters cloud properties indirectly. Many operational numerical weather prediction models account for aerosol direct effects by using climatological mean concentrations and neglect indirect effects. This simplification may lead to shortcomings in model forecasts during outbreaks of Saharan dust towards Europe, when climatological mean dust concentrations deviate strongly from actual concentrations. This study investigates errors in model analyses and short‐range forecasts during such events. We investigate a pronounced dust event in March 2021 using the pre‐operational ICOsahedral Nonhydrostatic weather and climate model with Aerosols and Reactive Trace gases (ICON‐ART) with prognostic calculation of dust and the operational European Centre for Medium‐Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS) model, which deploys a dust climatology. We compare model analysis and forecast with measurements from satellite and in situ instruments. We find that inclusion of prognostic aerosol and direct radiative effects from dust improves forecasts of surface radiation during clear‐sky conditions. However, dust‐induced cirrus clouds are strongly underestimated, highlighting the importance of representing indirect effects adequately. These findings are corroborated by systematic quantification of forecast errors against satellite measurements. For this we construct an event catalogue with 49 dust days over Central Europe between January 2018 and March 2022. We classify model cells by simulated and observed cloudiness and simulated dustiness in the total atmospheric column. We find significant overestimations of brightness temperature for cases with dust compared with cases without dust. For surface shortwave radiation, we find median overestimations of 6.2% during cloudy conditions with dust optical depth greater than 0.1, however these are not significant compared with cloudy conditions without dust. Our findings show that the pre‐operational ICON‐ART and the operational IFS model still do not reproduce cloudiness adequately during events with Saharan dust over Central Europe. Missing implementations of prognostic dust, particularly of indirect effects on cloud formation, lead to significant underestimations of cloudiness and potentially overestimations of surface radiation.

中文翻译：

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撒哈拉沙尘爆发对欧洲短期天气预报误差的影响

矿物尘埃是质量最丰富的大气气溶胶，直接与辐射相互作用并间接改变云的特性。许多业务数值天气预报模型通过使用气候平均浓度来解释气溶胶的直接影响，而忽略间接影响。这种简化可能会导致模型预测在撒哈拉沙尘向欧洲爆发期间出现缺陷，因为气候平均沙尘浓度与实际浓度有很大偏差。本研究调查了此类事件期间模型分析和短期预测中的错误。我们使用预运行的含气溶胶和活性微量气体的 ICOsahedral 非静水天气和气候模型 (ICON-ART) 以及运行中的欧洲中期天气预报中心 (ECMWF) 来调查 2021 年 3 月的一次明显沙尘事件，并进行沙尘预测计算综合预报系统（IFS）模型，部署了沙尘气候学。我们将模型分析和预测与卫星和现场仪器的测量结果进行比较。我们发现，将预测性气溶胶和灰尘的直接辐射效应纳入其中可以改善晴空条件下表面辐射的预测。然而，尘埃引起的卷云被严重低估，凸显了充分表示间接影响的重要性。这些发现通过卫星测量预测误差的系统量化得到了证实。为此，我们构建了一个包含 2018 年 1 月至 2022 年 3 月期间中欧 49 个沙尘日的事件目录。我们根据模拟和观测到的总大气柱中的云量和模拟沙尘量对模型单元进行分类。我们发现，与没有灰尘的情况相比，有灰尘的情况下的亮温明显高估。对于表面短波辐射，我们发现在尘埃光学深度大于 0.1 的多云条件下，中值高估了 6.2%，但与没有尘埃的多云条件相比，这些并不显着。我们的研究结果表明，运行前的 ICON-ART 和运行中的 IFS 模型仍然不能充分再现中欧上空撒哈拉沙尘事件期间的云量。缺少预测尘埃的实施，特别是对云形成的间接影响，导致对云量的严重低估和对表面辐射的潜在高估。