Ground-based Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations of NO₂ and H₂CO at Kinshasa and comparisons with TROPOMI observations

Abstract NO 2 H 2 CO tropospheric vertical column densities (VCDtropo) performed for the first time in the city of Kinshasa. These measurements were conducted between November 2019 and July 2021 and processed using the standardized inversion tools developed in the ESA FRM4DOAS (Fiducial Reference Measurements for Ground-Based DOAS Air-Quality Observations) project. The retrieved geophysical quantities are used to validate column observations from the TROPOspheric Monitoring Instrument (TROPOMI) over Kinshasa. In the validation, we experiment with three different comparison cases of increasing complexity. In the first case, a direct comparison between MAX-DOAS observations (hourly average of MAX-DOAS VCDtropo at overpass) and TROPOMI shows an underestimation of TROPOMI with a median bias of - 38  % for NO 2 - 39  % for H 2 CO based on monthly comparison. The second case takes into account the different vertical sensitivities of the two instruments and the a priori profile. We note significant changes in the median bias for both compounds: - 12  % for NO 2 + 11  % for H 2 CO. The third case builds on the second case by considering also the direction of sight of the MAX-DOAS. For this third case, we find a median bias of + 44  % for NO 2 + 4  % for H 2 CO. However this case is impacted by low sampling and is considered less reliable. The findings from this study underscore the significance of employing a realistic a priori profile in TROPOMI column extraction, particularly within heavily polluted urban zones like Kinshasa. The investigation also highlights the necessity for prudence when integrating the MAX-DOAS line of sight due to the noise generated during subsampling and the limited horizontal sensitivity of MAX-DOAS observations. Importantly, the study further reveals the pronounced pollution levels of NO 2 H 2 CO and aerosols in both the city of Kinshasa and its adjacent regions, underscoring the imperative for consistent monitoring and effective regulatory measures by local authorities.

Angaben zum Objekt

• Standort: Deutsche Nationalbibliothek Frankfurt am Main
• Umfang: Online-Ressource
• Sprache: Englisch

Verweise und Beziehungen

• Erschienen in: Ground-based Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations of NO₂ and H₂CO at Kinshasa and comparisons with TROPOMI observations ; volume:16 ; number:21 ; year:2023 ; pages:5029-5050 ; extent:22 ; Atmospheric measurement techniques ; 16, Heft 21 (2023), 5029-5050 (gesamt 22)

Beteiligte, Orts- und Zeitangaben

• Urheber: Yombo Phaka, Rodriguez ; Merlaud, Alexis ; Pinardi, Gaia ; Friedrich, Martina M. ; Van Roozendael, Michel ; Müller, Jean-François ; Stavrakou, Trissevgeni ; De Smedt, Isabelle ; Hendrick, François ; Dimitropoulou, Ermioni ; Bopili Mbotia Lepiba, Richard ; Phuku Phuati, Edmond ; Djibi, Buenimio Lomami ; Jacobs, Lars ; Fayt, Caroline ; Mbungu Tsumbu, Jean-Pierre ; Mahieu, Emmanuel

Weitere Informationen

• DOI: 10.5194/amt-16-5029-2023
• URN: urn:nbn:de:101:1-2023110203161326697844
• Rechteinformation: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Letzte Aktualisierung: 14.08.2025, 11:03 MESZ