GAW Report No. 205 - IGAC Project

CHAPTER 6 - EUROPEC) The MEGAPOLI campaignThe campaign, performed in the framework of the EC FP7 project MEGAPOLI, aimed at abetter quantification of primary and secondary organic aerosol sources and their relation to gaseousprecursors, at the example of a big European Megacity, the Paris region. Indeed, these aerosolfractions make up an important contribution to urban fine particle matter and their sources areamong the most uncertain. The campaign design included three primary and four secondary fixedground measurement sites, an aircraft, and five mobile platforms (Figure 15). Fixed sites weredistributed over urban and peri-urban areas. Mobile platforms allowed sampling the pollution plumeand background conditions. For many sites, complete instrumentation was set-up comprisingaerosol chemistry and physical properties as well as components of gas phase chemistry. Thesummer part of the campaign took place in July 2009 while the winter part took place from January15 to February 15, 2010. More than 25 laboratories participated (funded by EC, from Frenchnational funding, or from own means).Figure 15 - MEGAPOLI campaign set-up3 primary sites => full in situ measurements (LHVP, SIRTA, Livry_Gargan / + meteo at SIRTA3 secondary sites => lidar and spectrospcopic measurements / or in some situ3 mobile labs => in situ measurements, aerosol characterisation1 mobile lab => lidar measurements1 mobile lab => MAXDOAS1 aircraft ATR-42 => full in situ measurements (SAFIRE, CNRS, MPI)Additional lidar network in winter (red stars)The campaign was clearly a success, with measurement coverage above 90%. At themoment, measurements are being analyzed and quality checked by partners. Measurementquick-looks have already been submitted to the campaign database at LISA(http://megapoli.lisa.univ-paris12.fr/). First interesting results include:• From airborne primary pollutant measurements, the pollution plume was still well defined atmore than one hundred kilometres downwind from the agglomeration.• Very preliminary attribution of organic aerosol (OA) from AMS mass spectrometer urban andperi-urban measurements during the summer campaign shows a large fraction of oxidisedorganic aerosol (OOA) of secondary origin and a smaller fraction of unoxidised organicaerosol (HOA) of primary origin. At the urban site, about half of OA is water soluble,corresponding probably to classical secondary organic aerosol, another half is waterinsoluble, corresponding probably to primary and chemically processed primary OA.• Significant new particle formation events were observed in the area during the whole monthof the summer campaign. These events were assisted by the relatively low particulatematter concentration levels and resulting low surface area during most of July 2009.207