African dust outbreaks over the western Mediterranean Basin: 11-year characterization of atmospheric circulation patterns and dust source areas”, paper published in Atmospheric Chemistry and Physics

In this paper the occurrence of African dust outbreaks over different areas of the western Mediterranean Basin were identified for the period 2001-2011, and the main atmospheric circulation patterns causing these episodes were objectively characterized. For this purpose, two different but complementary methods for the classification of atmospheric variable fields (K-means and Principal Components) were used. Also, the potential source areas of mineral dust associated to each circulation pattern were identified by a trajectory statistical method (Redistributed Concentration Field method).

Four circulation types were found.  Pattern I accounted for 24% of the total number of African dust episodes in the studied area, and was found to be responsible of the transport of dust mainly in summer from Western Sahara, southern Morocco and Tunisia. Pattern IV accounted for 33% of the episodes and brings dust mainly from areas of northern and southern Algeria in summer and autumn, respectively. Pattern II accounted for 31% of the episodes and favored the transport of dust mainly from northern Algeria, both in spring and summer. Finally, pattern III was the less frequently observed (accounted for the 12% of the episodes), and mainly occurred in spring and with less intensity in winter, carrying dust from Western Sahara and southern Morocco.

Finally, an impact index to estimate the incidence of the African dust outbreaks produced during each of the four circulation patterns cited above, in the areas of study, was calculated.

This study points out that the most intense African dust episodes over the western Mediterranean Basin during the 2001-2011 period were produced in the summer season by the circulation pattern I over the western side of the Iberian Peninsula, and the circulation pattern IV over the central and eastern sides of the Iberian Peninsula and the Balearic Islands.

For more details about this work please refer to: P. Salvador , S. Alonso-Pérez , J. Pey , B. Artíñano , J. J. de Bustos , A. Alastuey , and X. Querol. African dust outbreaks over the western Mediterranean Basin: 11-year characterization of atmospheric circulation patterns and dust source areas, Atmos. Chem. Phys., 14, 6759–6775, 2014, doi:10.5194/acp-14-6759-2014.