The heidelberg airborne imaging DOAS instrument (HAIDI) - A novel imaging DOAS device for 2-D and 3-D imaging of trace gases and aerosols

Many relevant processes in tropospheric chemistry take place on rather small scales (e.g., tens to hundreds of meters) but often influence areas of several square kilometer. Thus, measurements of the involved trace gases with high spatial resolution are of great scientific interest. In order to identify individual sources and sinks and ultimately to improve chemical transport models, we developed a new airborne instrument, which is based on the well established Differential Optical Absorption Spectroscopy (DOAS) method. The Heidelberg Airborne Imaging DOAS Instrument (HAIDI) is a passive imaging DOAS spectrometer, which is capable of recording horizontal and vertical trace gas distributions with a resolution of better than 100 m. Observable species include NO₂, HCHO, C₂H₂O₂, H₂O, O₃, O₄, SO₂, IO, OClO and BrO. Here we give a technical description of the instrument including its custom-built spectrographs and CCD detectors. Also first results from measurements with the new instrument are presented. These comprise spatial resolved SO₂ and BrO in volcanic plumes, mapped at Mt. Etna (Sicily, Italy), NO₂ emissions in the metropolitan area of Indianapolis (Indiana, USA) as well as BrO and NO₂ distributions measured during arctic springtime in context of the BRomine, Ozone, and Mercury EXperiment (BROMEX) campaign, which was performed 2012 in Barrow (Alaska, USA).