Presenting SAPUSS: Solving Aerosol Problem by Using Synergistic Strategies in Barcelona, Spain

This paper presents the summary of the key ob- jectives, instrumentation and logistic details, goals, and ini- tial scientific findings of the European Marie Curie Action SAPUSS project carried out in the western Mediterranean Basin (WMB) during September–October in autumn 2010. The key SAPUSS objective is to deduce aerosol source char- acteristics and to understand the atmospheric processes re- sponsible for their generations and transformations – both horizontally and vertically in the Mediterranean urban en- vironment. In order to achieve so, the unique approach of SAPUSS is the concurrent measurements of aerosols with multiple techniques occurring simultaneously in six moni- toring sites around the city of Barcelona (NE Spain): a main road traffic site, two urban background sites, a regional back- ground site and two urban tower sites (150 m and 545 m above sea level, 150 m and 80 m above ground, respectively).SAPUSS allows us to advance our knowledge sensibly of the atmospheric chemistry and physics of the urban Mediter- ranean environment. This is well achieved only because of both the three dimensional spatial scale and the high sam- pling time resolution used. During SAPUSS different me- teorological regimes were encountered, including warm Sa- haran, cold Atlantic, wet European and stagnant regional ones. The different meteorology of such regimes is herein described. Additionally, we report the trends of the param- eters regulated by air quality purposes (both gaseous and aerosol mass concentrations); and we also compare the six monitoring sites. High levels of traffic-related gaseous pollu- tants 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 compared to ground level ones. The examination of the verti- cal profiles clearly shows the predominant influence of NO x on ozone concentrations, and a source of ozone aloft. Analy- sis of the particulate matter (PM) mass concentrations shows an enhancement of coarse particles (PM 2 . 5 − 10 ) at the urban ground level ( + 64 %, average 11.7 μg m − 3 ) but of fine ones (PM 1 ) at urban tower level ( + 28 %, average 14.4 μg m − 3 ) . These results show complex dynamics of the size-resolved PM mass at both horizontal and vertical levels of the study area. Preliminary modelling findings reveal an underestima- tion of the fine accumulation aerosols. In summary, this pa- per lays the foundation of SAPUSS, an integrated study of relevance to many other similar urban Mediterranean coastal environment sites