Airborne measurement of peroxy radicals in polluted air masses of East Asian origin during EMeRGe.

Peroxy radicals are involved in the catalytic oxidation of the hydrocarbons and play a key rolein the O3 budget and in the oxidation capacity of the atmosphere. The accurate measurementof these radicals provides therefore essential information to the EMeRGe (Effect ofMegacities on the Transport and Transformation of Pollutants on the Regional to GlobalScales) project, which investigates the processing and transformation of polluted outflowsfrom Major Population Centres (MPCs). Airborne measurements of the total sum of peroxy radicals, RO2* = (HO2 + ∑RO2), where R is an organic group, were conducted in Europe and in East Asiawithin EMeRGe by using the PeRCEAS instrument (Peroxy Radical ChemicalEnhancement and Absorption Spectrometer), on board of the HALO research aircraft(www.halo.dlr.de). PeRCEAS successfully participated in 14 measurement flights during the EMeRGe Asiacampaign in spring 2018 with airbase in Tainan, Taiwan. Outflows from different MPCs inSouth East Asia were investigated and polluted air masses of different origin and compositionwere probed. This presentation will focus on the classification of the air masses encounteredaccording to the age and photochemical activity indicated by the RO2* measured. [ABSTRACT FROM AUTHOR]