Characterization of a mobile atmospheric simulation chamber for laboratory and field studies: DouAir

Atmospheric transformation processes have been extensively studied in the laboratory using simulation chambers with various designs and materials. These tools allow  kinetic experiments to be performed under well-controlled conditions whereby a selected volatile organic compound (VOC) is usually oxidized in synthetic air. While atmospheric chambers are invaluable to provide kinetic parameters that are needed in atmospheric chemical mechanisms, their limitation is that they do not test these chemical mechanisms under conditions that are representative of the complex atmosphere, i.e. containing multiple VOCs and inorganic species.

In the present work, a mobile rectangular atmospheric simulation chamber of ~ 9 m³, made of Teflon FEP foils, was built at IMT Lille Douai for laboratory and field studies. The whole setup – called DouAir – can be easily disassembled, transported and deployed in the field. This new tool allows trapping of real air masses on-site, providing observations on the fate of reactive trace gases, which when compared to box model simulations can provide a critical test of our understanding of atmospheric chemistry. The chamber allows both solar and artificial irradiation, the irradiance being monitored by spectroradiometry. The chamber is equipped with a large array of analytical instruments, including PTR-ToFMS and GC-MS for VOC measurements, CRM for total OH reactivity, PERCA for peroxy radicals, O₃ and NO_x analyzers, and SMPS for aerosols. Here we describe the DouAir setup and will discuss characterization experiments carried out to validate the chamber. DouAir was tested for the first time during an intensive field campaign in the Landes forest (France) during summer 2018: CERVOLAND (Characterization of Emissions and Reactivity of Volatile Organic Compounds in the Landes Forest). Examples of experiments performed during CERVOLAND will be presented.