Mini-DOAS measurements during HALO phase II missions WISE, CAFE, EmerGe, and CoMet, and retrieval, interpretation and dissemination of the data collected during previous HALO missions

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The present proposal aims at two objectives. The first objective addresses the participation of the mini-DOAS instrument in the HALO missions WISE, CAFE, EmerGe, and CoMet, which are planned for the period mid-2016 to mid-2019. The second objective concerns the spectral retrieval of the data not yet processed, the concentration and profile retrieval of the targeted gases, their interpretation in conjunction with complementary measurements, and the dissemination of the obtained results. For the latter study three scientific objectives have been identified: 1. Identification and quantification of the sources and sinks of NOx and the photochemistry NOy in the troposphere and lower stratosphere (UTLS) for air masses of different origins (e.g., clean and pristine air versus NOx polluted air). For this study NO2 (and when present HONO) measurements of the mini-DOAS instrument are taken together with complementary measurements (AENEAS, AIMS, .. ) of NOy species (NO, total NOy, and HNO3). 2. An investigation on the relevance of volatile organic compounds for oxidation capacity of clean and pristine air versus polluted air, whereby mini-DOAS measurements of CH2O (and potentially C2H2O2) and complementary measurements of VOCs and CO are taken to test the oxidation mechanism VOC -> CH2O -> CO. 3. An assessment of the budget and photochemistry of bromine from mini-DOAS measured of BrO (and photochemical modelling to calculate total inorganic bromine from measured BrO) together with measurements of organic brominated species (by the University of Frankfurt) within the UTLS. All these studies will be used to test the predictions of different global chemistry transport models (CTMs) (EMAC, CLAMS, TOMCAT/SLIMCAT, ...) for the investigated species.