We present a spectral imager capable of measuring the 2-D distribution of atmospheric NO2
above well-delimited emission sources (power plant, city, etc.) with an unprecedent spatio-temporal resolution. Tests at a coal-fired power plant demonstrated its capability to observe dynamic processes such as the conversion from NO to NO2
in the early plume. Potential applications are: pollution sources monitoring, reactive plume chemistry models validation, ships and volcanic emissions tracking, etc.