Saharan Dust Events over the Valencian Community (Eastern Iberian Peninsula): Synoptic Circulation Patterns and Contribution to PM10 Levels

Abstract

ABSTRACT A characterization of Saharan Dust Events (SDE) passing over the Valencian Community (Eastern Spain) during the 2014-2017 period has been carried out. The assessment has focused on the following points: a) the study of their occurrence and impact on PM10 mass concentrations, b) the identification of the favorable synoptic patterns at 850 hPa associated with SDE by means of a cluster analysis and c) the application of the Gamma Probability Density Function (PDF) to fit the mass contributions of SDE to PM10 levels. The study has determined that the Valencian Community (VC) is under the influence of this kind of transport on ~26% of the days of the year, contributing 3.3 mg m-3 (~23%) to the PM10 average value. Five circulation scenarios (1-5) were identified. In scenario 1 (17.4%), the transport was produced due to a trough placed over the southwest of the Iberian Peninsula coupled with a high pressure system centred on Western Algeria, Tunisia and Eastern Libya. According to the PDF analysis, SDE characterized by this type of pattern were most likely to have elevated contributions to PM10 mass concentrations. In scenarios 3 (39.2%) and 5 (19.4%), a high pressure system located over North Africa was present. Both types of patterns also contributed to high concentrations of mineral dust in the VC. Scenarios 1, 3 and 5 were more frequent during summer months, specially type 3 (69%). On the other hand, types 2 (16.2%) and 4 (7.2%), both characterized by a deep low located over the West or Northwest of the Iberian Peninsula, were frequent in spring and, to a lesser extent, during the winter season. Scenarios 2 and 4 had a lower probability to contribute to high concentrations of mineral dust over the study area.