Instituto Dom Luíz, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Edifício C8, Piso 3, 1749-016 Lisboa, Portugal.
Instituto Dom Luíz, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Edifício C8, Piso 3, 1749-016 Lisboa, Portugal.
Sci Total Environ. 2020 May 15;717:137041. doi: 10.1016/j.scitotenv.2020.137041. Epub 2020 Jan 31.
The Iberian Peninsula (IP) is recurrently affected by dust transport from the Sahara Desert and from the semi-arid Sahel regions. African dust is one of the most important sources of particulate matter in the southern Mediterranean. Therefore, it is vital to understand the underlying processes that lead to episodes of air pollution associated to the occurrence of dust intrusions. This work proposes to make an extended characterization of the preferential circulation weather patterns associated to the onset of dust events affecting the IP between 2006 and 2016. Saharan dust intrusions were analysed and an automatic objective classification procedure was used to classify circulation weather patterns associated to dust events. The spatial distribution of intrusion episodes is not homogeneous throughout the IP, occurring less frequently at northern and northwestern locations than at central and southern sites. Moreover, days with Saharan dust intrusions were more frequent in summer months, and more probable to occur under regimes with a southerly component. Finally, two extreme events with high concentration of particulate matter were analysed relatively to their life-cycle and particle trajectories. The distinct extreme episodes can be associated to different synoptic situations. However, and despite different large-scale configurations, a south or south-easterly component over the region is responsible for the establishment of a dust transport from the Saharan region towards Iberia, and thus leading to the intrusion onset. These results were supported by the calculation of back-trajectories which allowed to source apportioning the particles' origin, through a clear trajectory of air parcels originating from northern Africa in both events. The proposed framework can be useful to the prediction of dust and air pollution events based on the forecast of circulation weather patterns, as the results show that these events across the IP are mainly induced by specific patterns.
伊比利亚半岛（IP）经常受到来自撒哈拉沙漠和半干旱萨赫勒地区的尘埃传输的影响。非洲尘埃是地中海南部颗粒物质的最重要来源之一。因此，了解导致与尘埃入侵相关的空气污染事件的潜在过程至关重要。这项工作旨在对 2006 年至 2016 年期间影响 IP 的尘埃事件相关的优先环流天气模式进行扩展特征描述。分析了撒哈拉尘埃入侵，并使用自动客观分类程序对与尘埃事件相关的环流天气模式进行了分类。入侵事件的空间分布在整个 IP 上并不均匀，在北部和西北部位置比在中部和南部位置发生的频率较低。此外，夏季月份发生撒哈拉尘埃入侵的天数较多，在南风成分较多的情况下发生的可能性更大。最后，对两个颗粒物浓度较高的极端事件进行了分析，比较了它们的生命周期和颗粒轨迹。明显的极端事件可以与不同的天气形势相关联。然而，尽管存在不同的大尺度配置，但该地区的南风或东南风成分负责建立从撒哈拉地区向伊比利亚半岛的尘埃输送，从而导致入侵的开始。这些结果得到了后向轨迹计算的支持，该计算允许通过两个事件中源自北非的空气团的清晰轨迹来对颗粒的来源进行源分配。所提出的框架可用于基于环流天气模式的预测来预测尘埃和空气污染事件，因为结果表明，这些事件在整个 IP 上主要是由特定的模式引起的。
