Total OH reactivity measurements in Paris during the 2010 MEGAPOLI winter campaign C. Dolgorouky1, V. Gros1, R. Sarda-Esteve1, V. Sinha2, J. Williams3, N. Marchand4, S. Sauvage5,6, L. Poulain7, J. Sciare1, and B. Bonsang1 1Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Unité Mixte CEA-CNRS-UVSQ (Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université de Versailles Saint-Quentin-en-Yvelines), UMR8212, 91198 Gif-sur-Yve 2Indian Institute of Science Education and Research (IISER) Mohali, Sector 81 SAS Nagar, Manauli PO Punjab 140306, India 3Max Planck Institute for Chemistry, Air Chemistry Department, 55128 Mainz, Germany 4Aix-Marseille Université, CNRS, LCE FRE 3416, 13331, Marseille, France 5Université de Lille Nord de France, 59000 Lille, France 6Ecole de Mines Douai, Departement Chimie environnement, 59508 Douai, France 7Leibniz – Institut für Troposphärenforschung (IFT), Leipzig, Germany
Abstract. Hydroxyl radicals play a central role in the troposphere as they control the
lifetime of many trace gases. Measurement of OH reactivity (OH loss rate) is
important to better constrain the OH budget and also to evaluate the
completeness of measured VOC budget. Total atmospheric OH reactivity was
measured for the first time in an European Megacity: Paris and its
surrounding areas with 12 million inhabitants, during the MEGAPOLI winter
campaign 2010. The method deployed was the Comparative Reactivity Method
(CRM). The measured dataset contains both measured and calculated OH
reactivity from CO, NOx and VOCs measured via PTR-MS, GC-FID and GC-MS
instruments. The reactivities observed in Paris covered a range from
10 s−1 to 130 s−1, indicating a large loading of chemical reactants.
The present study showed that, when clean marine air masses influenced
Paris, the purely local OH reactivity (20 s−1) is well explained by the
measured species. Nevertheless, when there is a continental import of air
masses, high levels of OH reactivity were obtained (120–130 s−1) and
the missing OH reactivity measured in this case jumped to 75%. Using
covariations of the missing OH reactivity to secondary inorganic species in
fine aerosols, we suggest that the missing OH reactants were most likely
highly oxidized compounds issued from photochemically processed air masses
of anthropogenic origin.
Citation: Dolgorouky, C., Gros, V., Sarda-Esteve, R., Sinha, V., Williams, J., Marchand, N., Sauvage, S., Poulain, L., Sciare, J., and Bonsang, B.: Total OH reactivity measurements in Paris during the 2010 MEGAPOLI winter campaign, Atmos. Chem. Phys., 12, 9593-9612, doi:10.5194/acp-12-9593-2012, 2012.