Document Details

Document Type : Article In Journal 
Document Title :
Simplifying aerosol size distributions modes simultaneously detected at four monitoring sites during SAPUSS
نمط مبسط لتوزيع حجم الهبو المقدر فى أربع محطات رصد فى نفس الوقت خلال سابوس
 
Subject : Enviromental sciences 
Document Language : English 
Abstract : The analysis of aerosol size distributions is a useful tool for understanding the sources and the processes influencing particle number concentrations (N) in urban areas. Hence, during the one month SAPUSS campaign (Solving Aerosol Problems by Using 5 Synergistic Strategies, EU Marie Curie Action) in autumn 2010 in Barcelona (Spain), four SMPS (Scanning Mobility Particle Sizers) were simultaneously deployed at four monitoring sites: a road side (RSsite), an urban background site located in the city (UBsite), an urban background located in the nearby hills of the city (Torre Collserola, TCsite) and a regional background site located about fifty km from the Barcelona urban 10 areas (RBsite). The spatial distribution of sites allows study of the aerosol temporal vari-ability as well as the spatial distribution, progressively moving away from urban aerosol sources. In order to interpret the datasets collected, a k-means cluster analysis was performed on the combined SMPS datasets. This resulted in nine clusters describing all aerosol size distributions from the four sites. In summary there were three main cat- 15 egories (with three clusters in each category): “Traÿc” (Traÿc 1 “Tclus_1” – 8 %, Traÿc 2 “Tclus_2” – 13 %, Traÿc 3, “Tclus_3” – 9 %), “Background Pollution” (Urban Background 1 “UBclus_1” – 21 %, Regional Background 1, “RBclus_1” – 15 %, Regional Background 2, “RBclus_2” – 18 %) and “Special cases” (Nucleation “NUclus” – 5 %, Regional Nitrate, “NITclus” – 6 %, and Mix “MIXclus” – 5 %). As expected, the frequency of traÿc clusters 20 (Tclus_1–3) followed the order RSsite, UBsite, TCsite, and RBsite. These showed typical traÿc modes mainly distributed at 20–40 nm. The urban background sites (UBsite and TCsite) reflected also as expected urban background number concentrations (average values, N = 2.4 × 104 cm−3 relative to 1.2 × 105 cm−3 seen at RSsite). The cluster de-scribing the urban background pollution (UBclus_1) could be used to monitor the sea 25 breeze circulation towards the regional background study area. Overall, the RBsite was mainly characterised by two di erent regional background aerosol size distributions: whilst both exhibited low N (2.6 × 103 for RBclus_1 and 2.3 × 103 cm−3 for RBclus_2), RBclus_1 had average PM10 concentrations higher than RBclus_1 (30 vs. 23 µgm−3). As 27389 regards the minor aerosol size distribution clusters, the “Nucleation” cluster was ob-served during daytime whilst the “Regional Nitrate” was mainly seen at night. The ninth cluster (“Mix”) was the least well defined and likely composed of a number of aerosol sources. When correlating averaged values of N, NO2 and PM (particulate mass) for each k-means cluster, a linear correlation between N and NO2 with values progressively increasing from the regional site RBsite to the road site RSsite was found. This points to vehicular traÿc as the main source of both N and NO2. By contrast, such an association does not exist for the case of the nucleation cluster, where the highest N is found with 10 low NO2 and PM. Finally, the clustering technique allowed study of the impact of meteorological pa-rameters on the traÿc N emissions. This study confirms the shrinking of freshly emit-ted particles (by about 20 % within 1 km in less than 10 min; Dall’Osto et al., 2011a) as particles are transported from the traÿc hot spots towards urban background environ- 15 ments. Additionally, for a given well defined aerosol size distribution (Tclus_2) associated to primary aerosol emissions from road traÿc we found that N5–15 nm concentrations can vary up to a factor of eight. Within our measurement range (5–228 nm), we found that ultrafine particles within the range 5–15 nm are the most dynamic, being a complex ensemble of primary evapo- rating traÿc particles, traÿc tailpipe new particle formation and non-traÿc new particle formation. 
ISSN : 1680-7316 
Journal Name : Atmospheric Chemistry And Physics 
Volume : 14 
Issue Number : 14 
Publishing Year : 1435 AH
2014 AD 
Article Type : Article 
Added Date : Monday, May 26, 2014 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
M. BrinesBrines, M. Researcher  
M. Dall’OstoDall’Osto, M. Researcher  
D. C. S. BeddowsBeddows, D. C. S.Researcher  
R. M HarrisonHarrison, R. M Researcher  
X. QuerolQuerol, X. Researcher  

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