High resolution nitrogen dioxide observations: retrieval, evaluation, and interpretation

Abstract:

The Airborne Compact Atmospheric Mapper (ACAM) deployed during the DISCOVER-AQ Maryland field campaign made hyperspectral remote sensing measurements in the 304-910 nm range allowing observations of several tropospheric pollutants including nitrogen dioxide (NO₂) at an unprecedented spatial resolution of 1.5x0.75 km². We apply the DOAS method, include high resolution information for surface reflectivity and vertical distributions of NO₂ and aerosols, and account for temporal variation in atmospheric NO₂ to retrieve lower tropospheric NO₂ column. We compare NO₂ from ACAM with observations from in-situ aircraft, ground-based PANDORA, and space-based OMI, and NO₂ simulation from air quality models. The high resolution ACAM measurements offer not only new insights into our understanding of atmospheric composition and chemistry through observation of sub-sampling variability in typical satellite and model resolutions, but also opportunities for algorithm improvements for upcoming geostationary air quality missions.