High-Resolution NO2 Observations from Space

Abstract:

The Tropospheric Monitoring Instrument (TROPOMI), which has a spatial resolution of approximately 3.5x5.5 km² in the visible band, provides a unique dataset for NO₂. Pollution plumes from emission sources like power plants, biomass burning, and cities are observed in single overpass data of TROPOMI. From the TROPOMI NO₂ data, the plume location and emissions can be quantified on a daily basis.

Building on the success of TROPOMI, new satellite missions are planned with even higher spatial resolution for NO₂. For example, the European CO₂ mission (CO2M) will provide NO₂ data with a spatial resolution of 2x2 km² and the proposed TANGO mission (Twin ANthropogenic Greenhouse Gas Observers) is planning a resolution of 300x300m². For both CO2M and TANGO, the NO₂ data are supporting the CO₂ observations by locating the pollution plume. However, these data will also be very useful for air quality applications, in particular for the quantification of emission sources.

In this contribution we will discuss the benefits and challenges of high-spatial resolution NO₂ data. We will show analyses of TROPOMI data at 2.4x1.8 km² sampling, using a measurement mode that was used only in the commissioning phase. Also, model data from a large eddy simulation (LES) model is used to simulate data at higher spatial resolutions. Aspects that are discussed include the signal-to-noise ratio versus spatial resolution and coverage, as well as the effects of atmospheric turbulence on flux estimates.