Develop realistic high-resolution NO2 retrievals from TROPOMI.
TROPOMI on the Sentinel-5P platform is the leading instrument to monitor NO2 from space, providing city-scale measurements of NO2 pollution. The imagery and scientific results from TROPOMI are generating wide attention from academia and the general public. They are used to study the impacts of COVID-19 and to assess the nitrogen crisis in The Netherlands and worldwide.
To reduce uncertainties and to innovate KNMI’s retrievals for the next generation NO2 capabilities with the CO2M and Sentinel-5 missions, we improve the modeling of atmospheric photon transport and implement fine-scale information on the state of the atmosphere to develop realistic high-resolution NO2 retrievals. This will enable new science and applications of the data, maintain KNMI’s scientific infrastructure at top level, and help upcoming European sensors.
The TROPOMI NO2 data product has been extensively validated, tested, and used. This research confirmed that two of the three main ingredients of the NO2 retrieval, the NO2 slant column density (SCD) and the stratospheric column estimate, are of sufficient quality to fulfil the TROPOMI Mission Requirements [ESA, 2017]. The third component of the retrieval however, the air mass factor (AMF), a measure for the vertical sensitivity of the measurement is likely biased high. AMFs are flawed because of too little physical realism in the radiative transfer model calculations, and because the input data are too coarse or suffer from structural uncertainty (Lorente et al. ).
The overall goal of NO2NEXT is to fundamentally improve KNMI’s TROPOMI NO2 retrievals through a better understanding of
and how these affect the retrieval and interpretation of the satellite data.
Our work in this project will be guided by 3 objectives:
Riess, T. C. V. W., Boersma, K. F., van Vliet, J., Peters, W., Sneep, M., Eskes, H., and van Geffen, J.: Improved monitoring of shipping NO2 with TROPOMI: decreasing NOx emissions in European seas during the COVID-19 pandemic, Atmos. Meas. Tech., 15, 1415–1438, https://doi.org/10.5194/amt-15-1415-2022, 2022.
van Geffen, J., Eskes, H., Compernolle, S., Pinardi, G., Verhoelst, T., Lambert, J.-C., Sneep, M., ter Linden, M., Ludewig, A., Boersma, K. F., and Veefkind, J. P.: Sentinel-5P TROPOMI NO2 retrieval: impact of version v2.2 improvements and comparisons with OMI and ground-based data, Atmos. Meas. Tech., 15, 2037–2060, https://doi.org/10.5194/amt-15-2037-2022, 2022.
Douros, J., Eskes, H., van Geffen, J., Boersma, K. F., Compernolle, S., Pinardi, G., Blechschmidt, A.-M., Peuch, V.-H., Colette, A., and Veefkind, J. P.: Comparing Sentinel-5P TROPOMI NO2 column observations with the CAMS-regional air quality ensemble, submitted to Geoscientific Model Development, egusphere-2022-365, 2022.