Abstract The study focused on an exceptional desert dust outbreak episode, in particular on the role of atmospheric circulation transporting high amounts of dust toward Portugal in February 2017. In order to assess the atmospheric conditions behind the mineral dust layer observed in Evora from lidar observations, two simulations were performed with the Meso-NH model including dust emission but with different initialization times. The simulations were performed over a single domain that covers 3000 × 3600 km and with a 10 km resolution. The episode was governed by a variety of complex interactions between surface and atmospheric dynamics during nine days. The study highlights the role played by the regional orography of the North Africa producing mesoscale circulations, namely the airflow convergence and the development of a cyclonic vortex in the lower troposphere. The intense winds near the surface was the main factor controlling the mobilization of mineral dust particles. In addition, a low pressure system approaching from mid-latitudes was fundamental for the long-lasting event, as well as for the transport of desert dust toward Portugal.

中文翻译：

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撒哈拉上空的中尺度气旋涡旋如何导致伊比利亚西南部发生沙尘暴

摘要 该研究侧重于一次特殊的沙漠沙尘暴发事件，特别是 2017 年 2 月大气环流向葡萄牙输送大量灰尘的作用。为了评估埃武拉从激光雷达观测到的矿物灰尘层背后的大气条件，使用 Meso-NH 模型进行了两次模拟，包括粉尘排放，但初始化时间不同。模拟是在覆盖 3000 × 3600 公里和 10 公里分辨率的单个域上进行的。这一事件是由 9 天内地表和大气动力学之间的各种复杂相互作用所控制的。该研究强调了产生中尺度环流的北非区域地形所发挥的作用，即气流会聚和对流层低层气旋涡旋的发展。地表附近的强风是控制矿物粉尘颗粒流动的主要因素。此外，来自中纬度地区的低压系统对于这一长期持续的事件以及沙漠尘埃向葡萄牙的输送至关重要。