Presenting SAPUSS: solving aerosol problem by using synergistic strategies at Barcelona, Spain

Abstract. This paper presents the summary of the key objectives, instrumentation and logistic details, goals, and initial scientific findings of the Marie Curie Action FP7-EU SAPUSS project carried out in the Western Mediterranean Basin (WMB) from 20 September–20 October 2010. The experiment involved concurrent measurements of aerosols with multiple techniques occurring simultaneously. The key objective is to deduce point aerosol source characteristics and to understand the atmospheric processes responsible for their generations and transformations. The unique approach is the large variety of instrumentation deployed simultaneously in six monitoring sites in Barcelona (NE Spain) and around the city, including: a main road traffic site, two urban background sites, a regional background site and two tower sites (150 m and 545 m a.s.l., 150 m and 80 m above ground, respectively). The SAPUSS experiment allows us to interpret the variability of aerosols levels and composition in an Urban Mediterranean, an environment not well characterized so far. During SAPUSS different air mass scenarios were encountered, including warm Saharan, cold Atlantic, wet European and stagnant Regional ones and presenting different local meteorology and boundary layer conditions. Analysis of part of the data collected allows us to compare the monitoring sites as well as to draw scientific conclusions about relevant air quality parameters. High levels of traffic-related gaseous pollutants were measured at the urban ground level monitoring sites, whereas layers of tropospheric ozone were recorded at tower levels. Particularly, tower level night time average ozone concentrations (80 ± 25 μg m−3) were up to double than ground level ones. Particle number concentrations (N>5: 9980 ± 6500 cm−1, average of all measurements) were generally traffic dependent, although a contribution from two different types of nucleation events was also found. Analysis of the particulate matter (PM) mass concentrations shows an enhancement of coarse particles (PM2.5-10) at the urban ground level (+64%, average 11.7 μg m−3) but of fine ones (PM1) at urban tower level (+28%, average 14.4 μg m−3). Preliminary modeling findings reveal an underestimation of the fine accumulation aerosols. In summary, this paper lays the foundation of SAPUSS, an integrated study of relevance to many other similar urban Mediterranean coastal environment sites.

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