Abstract. This paper concerns an in-depth analysis of an exceptional incursion of mineral dust over Southern Europe in late March 2020. This event was associated with an anomalous circulation pattern leading to several days of PM₁₀ exceedances in connection with a dust source located in Central Asia a rare source of dust for Europe, more frequently affected by dust outbreaks from the Sahara desert. The synoptic meteorological configuration was analyzed in detail, while aerosol evolution during the transit of the dust cloud over Northern Italy was assessed at high time resolution by means of optical particle counting at three stations, namely Bologna, Trieste, and Mt. Cimone allowing to reveal transport timing among the three locations. Back-trajectory analyses supported by AOD (Aerosol Optical Depth) maps allowed to locate the mineral dust source area in the Aralkum region. The event was therefore analyzed through the observation of particle number size distribution with the support of chemical composition analysis. It is shown that PM₁₀ exceedance recorded is associated with a large fraction of coarse particles in agreement with mineral dust properties. Both in-situ number size distribution and vertical distribution of the dust plume were cross-checked by Lidar Ceilometer and AOD data from two nearby stations, showing that the dust plume, differently from those originated in the Sahara desert, traveled close to the ground up to a height of about 2 km. The limited mixing layer height caused by high concentrations of absorbing and scattering aerosols caused the mixing of mineral dust with other locally-produced ambient aerosols, thereby potentially increasing its morbidity effects.

中文翻译：

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2020 年 3 月在欧洲发生的亚洲异常沙尘事件的发展和演变

摘要。本文涉及对 2020 年 3 月下旬矿物粉尘异常入侵南欧的深入分析。该事件与导致数天 PM ₁₀的异常环流模式有关与位于中亚的粉尘源有关的超标，这是欧洲罕见的粉尘源，更常受到撒哈拉沙漠粉尘爆发的影响。详细分析了天气气象配置，同时通过三个站点（即博洛尼亚、的里雅斯特和 Cimone）的光学粒子计数以高时间分辨率评估了意大利北部尘埃云过境期间的气溶胶演化，从而揭示三个地点之间的运输时间。由 AOD（气溶胶光学深度）图支持的反向轨迹分析允许定位 Aralkum 地区的矿物尘源区域。因此，在化学成分分析的支持下，通过观察粒子数大小分布来分析该事件。结果表明 PM ₁₀记录的超标与大部分符合矿物粉尘特性的粗颗粒有关。通过激光雷达云高仪和附近两个站点的 AOD 数据交叉检查了尘羽的原位数量大小分布和垂直分布，表明与起源于撒哈拉沙漠的尘羽不同的是，尘羽接近地面向上移动到大约 2 公里的高度。由高浓度吸收和散射气溶胶引起的混合层高度有限，导致矿物粉尘与其他本地产生的环境气溶胶混合，从而可能增加其发病率。