Wet and dry African dust episodes over eastern Spain

Abstract

[1] The impact of the African dust on levels of atmospheric suspended particulate matter (SPM) and on wet deposition was evaluated in eastern Iberia for the period 1996-2002. An effort was made to compile both the SPM and wet episodes. To this end, the time series of levels of TSP and PM10 in Levantine air quality monitoring stations were evaluated and complemented with the computation of back trajectories, satellite images, and meteorological analysis. Wet deposition frequency was obtained from weekly collected precipitation data at a rural background station in which the African chemical signature was identified (mainly pH and Ca 2+ concentrations). A number of African dust episodes (112) were identified (16 episodes per year). In 93 out of the 112 (13 episodes per year) the African dust influence caused high SPM levels. In 49 out of 112 (7 episodes per year), wet deposition was detected, and the chemistry was influenced by dust. There is a clear seasonal trend with higher frequency of dust outbreaks in May-August, with second modes in March and October. Wet events followed a different pattern, with a marked maximum in May. Except for one event, December was devoid of African air mass intrusions. On the basis of seasonal meteorological patterns affecting the Iberian Peninsula, an interpretation of the meteorological scenarios causing African dust transport over Iberia was carried out. Four scenarios were identified with a clear seasonal trend. The impact of the different dust outbreak scenarios on the levels of PM10 recorded at a rural site (Monagrega, Teruel, Spain) in the period 1996-2002 was also evaluated.

Origin and pathways of the mineral dust transport to two Spanish EARLINET sites: Effect on the observed columnar and range-resolved dust optical properties

“…Backward trajectories analyses suggest three clusters over Saharan desert, which are the main contributors to dust intrusions over Barcelona and Granada, similarly to the scenarios described by Escudero et al (2005) and Valenzuela et al (2012). Our clustering analysis reveals a pathway from south to north, mainly in emission areas in Morocco and west of Algeria (cluster A), a pathway from west via an Atlantic arch with emission areas over West Sahara, Mauritania, south of Algeria and north of Mali (cluster B) and a pathway from east across the Mediterranean sea with emission areas over the remaining part of Algeria and Tunisia (cluster C).…”

Ambient Particulate Matter Concentration Levels and their Origin During Dust Event Episodes in the Eastern Mediterranean

“…These studies showed that over the eastern Mediterranean, most of the African dust affecting ground-based measurements was transported at surface levels. However, the transport of Sahara dust towards the western Mediterranean mostly occurs at relatively high atmospheric levels (Escudero et al 2005).…”

Identification of the Influence of African Dust on PM10 Concentrations at the Athens Air Quality Monitoring Network during the Period 2001-2010

“…This methodology, which was further developed and used by e.g. Escudero et al (2005) and Querol et al (2009), has been recently included in the guidelines for demonstration and subtraction of exceedances attributable to natural sources under the Directive 2008/50/EC on ambient air quality and cleaner air for Europe (EC, 2011). In particular, the PM 10 time series of concentrations at the AMA network stations were examined, high PM 10 levels (peaks) at each station were highlighted and a list of coincident peaks was created.…”