Biomass burning pollution in the South Atlantic upper troposphere: GLORIA trace gas observations and evaluation of the CAMS model

Abstract

Abstract. In this study, we present simultaneous airborne measurements of peroxyacetyl nitrate (PAN), ethane (C2H6), formic acid (HCOOH), methanol (CH3OH), and ethylene (C2H4) above the South Atlantic in September and October 2019. Observations were obtained from the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA), as two-dimensional altitude cross-sections along the flight path. The flights were part of the SouthTRAC (Transport and Composition in the Southern Hemisphere Upper Troposphere/Lower Stratosphere) campaign with the German High Altitude and Long range research Aircraft (HALO). On two flights (8 September 2019 and 7 October 2019), large enhancements of all these substances were found between 7 and 14 km altitude with maximum volume mixing ratios (VMRs) of 1000 pptv of PAN, 1400 pptv for C2H6, 800 pptv for HCOOH, 4500 pptv for CH3OH, and 200 pptv for C2H4. One flight shows a common filamentary structure in the trace gas distributions, while the second flight is characterized by one large plume. Using backward trajectories, we show that measured pollutants are likely originating from South America and central Africa, where elevated PAN VMRs are visible at the surface layer of the Copernicus Atmosphere Monitoring Service (CAMS) model during the weeks before both measurements. In comparison to simulation results of the CAMS reanalysis interpolated onto the GLORIA measurement geolocations, we show that the model is able to reproduce the overall structure of the measured pollution trace gas distributions. For PAN, the absolute VMRs are in agreement with the GLORIA measurements, too. However, C2H6 and HCOOH are generally underestimated by the model, while CH3OH and C2H4, the species with the shortest atmospheric lifetimes of the discussed pollution trace gases, are overestimated by CAMS. The good agreement between model and observations for PAN suggests that the general transport pathways and emissions locations are well captured by the model. The poorer agreement for other species is therefore most likely linked to model deficiencies in the representation of loss processes and emission strength.

Airborne glyoxal measurements in the marine and continental atmosphere: comparison with TROPOMI observations and EMAC simulations

“…For the EMeRGe-EU and EMeRGe-Asia missions, benzene (C 6 H 6 ), isoprene (C 5 H 8 ), and acetonitrile (CH 3 CN) are used to detect and differentiate between anthropogenic pollution and biomass burning plumes Krüger et al, 2022). Biomass burning plumes are further identified based on simultaneous measurements of CO (Tadic et al, 2017) and black carbon (Holanda et al, 2020) during CAFE-Africa and of CO (Müller et al, 2015;Kunkel et al, 2019), peroxyacetyl nitrate (PAN), ethane (C 2 H 6 ), formic acid (HCOOH), methanol (CH 3 OH), ethylene (C 2 H 4 ) (Johansson et al, 2022), and acetylene (C 2 H 2 ) (Sören Johansson, personal communication, February 2022) during the SouthTRAC mission and by visual inspection and air mass back-trajectory calculations for the ACRIDICON-CHUVA mission (Kluge et al, 2020).…”

The Mission Support System (MSS v7.0.4) and its use in planning for the SouthTRAC aircraft campaign

“…The Southern Hemisphere Transport, Dynamics, and Chemistry-Gravity Waves campaign (SouthTRAC-GW; Rapp et al, 2021) took place from September to November 2019, operating from bases located at Oberpfaffenhofen, Germany, and Rio Grande, Argentina. The scientific objectives were very diverse, ranging from examining air polluted by biomass burning in the tropics (Johansson et al, 2022) (and, as a target of opportunity, Australia; Ohneiser et al, 2022), the breakdown of the Antarctic polar vortex and the associated chemical and physical structure, the general chemical composition of the Southern Hemisphere's upper troposphere-lower stratosphere (Johansson et al, 2022), to studying gravity waves. Some exemplary outcomes from the gravity wave part of the SouthTRAC campaign include clear-air turbulence studies (Rodriguez Imazio et al, 2022;Dörnbrack et al, 2022), gravity wave propagation from the Southern Andes and the Antarctic peninsula into the mesosphere (Reichert et al, 2021;Conte et al, 2022), gravity wave observation and model intercomparison (Gisinger et al, 2022;Dörnbrack et al, 2022;Liu et al, 2022;Alexander et al, 2022), mountain waves drifting upwind of the Andes (Krasauskas et al, 2022), gravity wave refraction due to wind shear (Geldenhuys et al, 2022), and gravity waves from orographic and non-orographic sources (Alexander et al, 2022;de la Torre et al, 2022).…”

Airborne glyoxal measurements in the marine and continental atmosphere: Comparison with TROPOMI observations and EMAC simulations

“…ethylene (C 2 H 4 )(Johansson et al, 2022), and acetylene (C 2 H 2 ) (S.Johansson, private communication, Feb. 2022) during the SouthTRAC mission, and by visual inspection as well as air mass back trajectory calculations for the ACRIDICON-CHUVA mission(Kluge et al, 2020).https://doi.org/10.5194/acp-2022-416 Preprint. Discussion started: 14 July 2022 c Author(s) 2022.…”