Nitrogen Dioxide is both a primary pollutant with direct health effects and a key precursor of the secondary pollutant ozone. This paper reports on the development, characterisation and test flight of the Atmospheric Nitrogen Dioxide Imager (ANDI) remote sensing system. The ANDI system includes an imaging (UV)-vis grating spectrometer able to capture scattered sunlight spectra for the determination of tropospheric nitrogen dioxide (NO₂) concentrations by way of DOAS slant column

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... ty and vertical column density measurements. <br><br> Results are shown for an ANDI test flight over Leicester City in the UK. Retrieved NO₂ columns at a surface resolution of 80 m x 20 m revealed hot spots in a series of locations around Leicester City, including road junctions, the train station, major car parks, areas of heavy industry, a nearby airport (East Midlands) and a power station (Ratcliffe-on-Soar). In the city centre the dominant source of NO₂ emissions was identified as road traffic, contributing to a background concentration as well as producing localised hot spots. Quantitative analysis revealed a significant urban increment over the city centre which increased throughout the flight.