Aircraft-based 2- and 3D Trace Gas Measurements with HAIDI (Heidelberg Airborne Imaging DOAS Instrument) - Results of the EMeRGe Missions

Today, the majority of humanity lives in urban areas. Accordingly, major population centers are a significant source of a multitude of atmospheric emissions from human activity such as traffic, heating, industry or power generation. Pollutants directly impact the local inhabitant's health, but are also transported to neighbouring areas, undergo chemical evolution and can have an impact on climate. To understand and assess effective measures for reducing the effects, it is important to determine the source locations and strengths as well as relevant chemical processes.

Aircraft-based measurements can cover the gap between long-term ground-based and globe-covering satellite instruments with its high temporal and spatial coverage during flight time. Remote sensing methods in particular allow a fast and wide-spread probing of atmospheric trace gas distributions. Within this context, the HAIDI (Heidelberg Airborne Imaging DOAS Instrument) instrument was designed to provide data of extremely high temporal and spatial resolution (40m x 40m at 1.5 km flight altitude, 266m x 266m at 10 km flight altitude, at 10 ms temporal resolution) in 2D and 3D during overflight.

During the EMeRGe (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales) missions HAIDI was part of the comprehensive set of measurement equipment installed on the research airplane HALO (High Altitude and LOng range re-search aircraft) of the DLR (German Aerospace Center). The EMeRGe missions targeted the emission outflows of megacities to investigate their compositions and the atmospheric impact of urban pollution. One mission part was conducted in Europe (July 2017) and aimed at areas around Paris, London, the Po area, Madrid and the Benelux area. For contrast, the second mission part was based in Taiwan (March 2018) and investigated Taiwan cities, Bangkok, Manila, Japanese cities and China outflow.

HAIDI derived a number of trace gases such as NO2, SO2, BrO and HCHO. Due to large concentrations present, for NO2 and SO2 in particular it was possible to obtain high-resolution 2D data of megacity areas and plumes of megacities, powerplants and ships and estimate their emissions. We will present results of the HAIDI measurements during the EMeRGe mission.