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    Validation of GEMS operational v2.0 total column NO2 and HCHO during the GMAP/SIJAQ campaign

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    Bae(2025a).pdf (13.31Mb)
    Authors
    Bae, K.
    Song, C.K.
    Van Roozendael, M.
    Richter, A.
    Wagner, T.
    Merlaud, A.
    Pinardi, G.
    Friedrich, M.M.
    Fayt, C.
    Dimitropoulou, E.
    Lange, K.
    and Bösch, T.
    Zilker, B.
    Latsch, M.
    Behrens, L.K.
    Ziegler, S.
    Ripperger-Lukosiunaite, S.
    Kuhn, L.
    Lauster, B.
    Reischmann, L.
    Uhlmannsiek, K.
    Cede, A.
    Tiefengraber, M.
    Gebetsberger, M.
    Park, R.J.
    Lee, H.
    Hong, H.
    Chang, L.S.
    Jeon, K.
    Show allShow less
    Discipline
    Earth and related Environmental sciences
    Subject
    China
    Seoul [South Korea]
    South Korea
    Acid rain
    Damage detection
    Emission control
    Fiber optic sensors
    Fog
    High speed cameras
    Image resolution
    Ionosphere
    Liquid level indicators
    Motion picture cameras
    Network performance
    Outages
    Ozone layer
    Spectrometers
    Statistical process control
    Temperature indicating cameras
    Tropics
    Troposphere
    formaldehyde
    nitrogen dioxide
    Differential optical absorption spectroscopy
    Diurnal variation
    Environmental Monitoring
    Geostationary environmental monitoring spectrometer
    GMAP/SIJAQ
    Multi-Axis
    Multi-axis differential optical absorption spectroscopy
    Multi-Axis-
    Pandora
    Validation
    air quality
    atmospheric pollution
    atomic absorption spectroscopy
    correlation
    diurnal variation
    geostationary satellite
    nitrogen dioxide
    seasonal variation
    slope
    spatial resolution
    troposphere
    absorption spectroscopy
    air monitoring
    algorithm
    Article
    circadian rhythm
    climate change
    comparative study
    conceptual framework
    correlation coefficient
    multi axis differential optical absorption spectroscopy
    pollution
    radiation
    satellite integrated joint monitoring of air quality
    seasonal variation
    validation process
    Air quality
    Audience
    Scientific
    Date
    2025
    Metadata
    Show full item record
    Description
    The Geostationary Environmental Monitoring Spectrometer (GEMS), the first geostationary air quality instrument, onboard the GEO-KOMPSAT-2B (GK2B) satellite, produces hourly observations over Asia with 3.5 km × 8 km spatial resolution. To evaluate the GEMS L2 products, the National Institute of Environmental Research (NIER) organized the GEMS Map of Air Pollutants 2021 (GMAP2021) and the Satellite Integrated Joint monitoring of Air Quality 2022 (SIJAQ2022) campaigns during October 2021 to November 2021 and from June 2022 to July 2022, respectively. While GMAP2021 mainly targeted the SMA (Seoul Metropolitan Area), the SIJAQ2022 campaign extended to the southeastern area of South Korea. In this study, a comparison between Pandora and Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) products and an evaluation of the GEMS operational v2.0 total column NO2 and HCHO products are conducted. A comparative analysis between the Pandora (P189) and the IUP Bremen MAX-DOAS instrument at the Incheon NIER-ESC site was performed to analyze discrepancies between the retrieval processors (Pandora: PGN official processor, MAX-DOAS: MMF in FRM4DOAS framework). Aligning the viewing directions of both Pandora and MAX-DOAS leads to a significant increase in the slope and correlation coefficient from 0.87 to 0.96 and from 0.86 to 0.96, respectively, in the case of NO2 tropospheric columns. Similarly, for HCHO tropospheric columns, slope and correlation coefficient change from 0.94 to 1.09 and from 0.81 to 0.90 when matching the viewing geometries of both instruments. In contrast to tropospheric columns, total HCHO columns derived from Pandora (P189) direct-sun measurements show significantly larger values than the MAX-DOAS ones, with a mean relative difference (MRD) of 126 %. This bias can however be reduced to 33 % after suitable adjustment of the direct-sun retrieval settings. The GEMS v2.0 NO2 total column product, evaluated over 6 official PGN sites in South Korea, shows good agreement with a correlation coefficient of 0.87 and similar seasonal and diurnal NO2 variation. However, GEMS tends to report higher values than Pandora with a mean relative difference of +41 %. The magnitude of the GEMS overestimation is amplified in highly polluted conditions (i.e. during winter and at noontime). Compared to 6 MAX-DOAS stations and 6 Pandora stations, the GEMS HCHO product captures well the seasonal and diurnal variation of HCHO and shows good agreement both with MAX-DOAS and Pandora with slopes of 0.84 and 0.79, respectively, and correlation coefficients of 0.86 for both. Large columns, however, tend to be systematically underestimated.
    Citation
    Bae, K.; Song, C.K.; Van Roozendael, M.; Richter, A.; Wagner, T.; Merlaud, A.; Pinardi, G.; Friedrich, M.M.; Fayt, C.; Dimitropoulou, E.; Lange, K.; and Bösch, T.; Zilker, B.; Latsch, M.; Behrens, L.K.; Ziegler, S.; Ripperger-Lukosiunaite, S.; Kuhn, L.; Lauster, B.; Reischmann, L.; Uhlmannsiek, K.; Cede, A.; Tiefengraber, M.; Gebetsberger, M.; Park, R.J.; Lee, H.; Hong, H.; Chang, L.S.; Jeon, K. (2025). Validation of GEMS operational v2.0 total column NO2 and HCHO during the GMAP/SIJAQ campaign. , Science of the Total Environment, Vol. 974, A179190, DOI: 10.1016/j.scitotenv.2025.179190.
    Identifiers
    uri: https://orfeo.belnet.be/handle/internal/14019
    doi: http://dx.doi.org/10.1016/j.scitotenv.2025.179190
    url:
    Type
    Article
    Peer-Review
    Yes
    Language
    eng
    Links
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