• Login
     
    View Item 
    •   ORFEO Home
    • Royal Belgian Institute for Space Aeronomy
    • BIRA-IASB publications
    • View Item
    •   ORFEO Home
    • Royal Belgian Institute for Space Aeronomy
    • BIRA-IASB publications
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Sentinel-5P TROPOMI NO2 retrieval: impact of version v2.2 improvements and comparisons with OMI and ground-based data

    Thumbnail
    View/Open
    VanGeffen(2022a).pdf (12.45Mb)
    Authors
    Van Geffen, J.
    Eskes, H.
    Compernolle, S.
    Pinardi, G.
    Verhoelst, T.
    Lambert, J.-C.
    Sneep, M.
    Ter Linden, M.
    Ludewig, A.
    Boersma, K.F.
    Veefkind, J.P.
    Show allShow less
    Discipline
    Earth and related Environmental sciences
    Audience
    Scientific
    Date
    2022
    Metadata
    Show full item record
    Description
    Nitrogen dioxide (NO2) is one of the main data products measured by the Tropospheric Monitoring Instrument (TROPOMI) on the Sentinel-5 Precursor (S5P) satellite, which combines a high signal-to-noise ratio with daily global coverage and high spatial resolution. TROPOMI provides a valuable source of information to monitor emissions from local sources such as power plants, industry, cities, traffic and ships, and variability of these sources in time. Validation exercises of NO2 v1.2–v1.3 data, however, have revealed that TROPOMI's tropospheric vertical column densities (VCDs) are too low by up to 50 % over highly polluted areas. These findings are mainly attributed to biases in the cloud pressure retrieval, the surface albedo climatology and the low resolution of the a priori profiles derived from global simulations of the TM5-MP chemistry model. This study describes improvements in the TROPOMI NO2 retrieval leading to version v2.2, operational since 1 July 2021. Compared to v1.x, the main changes are the following. (1) The NO2-v2.2 data are based on version-2 level-1b (ir)radiance spectra with improved calibration, which results in a small and fairly homogeneous increase in the NO2 slant columns of 3 % to 4 %, most of which ends up as a small increase in the stratospheric columns. (2) The cloud pressures are derived with a new version of the FRESCO cloud retrieval already introduced in NO2-v1.4, which led to a lowering of the cloud pressure, resulting in larger tropospheric NO2 columns over polluted scenes with a small but non-zero cloud coverage. (3) For cloud-free scenes a surface albedo correction is introduced based on the observed reflectance, which also leads to a general increase in the tropospheric NO2 columns over polluted scenes of order 15 %. (4) An outlier removal was implemented in the spectral fit, which increases the number of good-quality retrievals over the South Atlantic Anomaly region and over bright clouds where saturation may occur. (5) Snow/ice information is now obtained from ECMWF weather data, increasing the number of valid retrievals at high latitudes. On average the NO2-v2.2 data have tropospheric VCDs that are between 10 % and 40 % larger than the v1.x data, depending on the level of pollution and season; the largest impact is found at mid and high latitudes in wintertime. This has brought these tropospheric NO2 closer to Ozone Monitoring Instrument (OMI) observations. Ground-based validation shows on average an improvement of the negative bias of the stratospheric (from −6 % to −3 %), tropospheric (from −32 % to −23 %) and total (from −12 % to −5 %) columns. For individual measurement stations, however, the picture is more complex, in particular for the tropospheric and total columns.
    Citation
    Van Geffen, J.; Eskes, H.; Compernolle, S.; Pinardi, G.; Verhoelst, T.; Lambert, J.-C.; Sneep, M.; Ter Linden, M.; Ludewig, A.; Boersma, K.F.; Veefkind, J.P. (2022). Sentinel-5P TROPOMI NO2 retrieval: impact of version v2.2 improvements and comparisons with OMI and ground-based data. , Atmospheric Measurement Technique, Vol. 15, Issue 7, 2037-2060, DOI: 10.5194/amt-15-2037-2022.
    Identifiers
    uri: https://orfeo.belnet.be/handle/internal/9899
    doi: http://dx.doi.org/10.5194/amt-15-2037-2022
    scopus:
    Type
    Article
    Peer-Review
    Yes
    Language
    eng
    Links
    NewsHelpdeskBELSPO OA Policy

    Browse

    All of ORFEOCommunities & CollectionsBy Issue DateAuthorsTitlesDisciplinesThis CollectionBy Issue DateAuthorsTitlesDisciplines
     

    DSpace software copyright © 2002-2016  DuraSpace
    Send Feedback | Cookie Information
    Theme by 
    Atmire NV