Measurement report: Hydrogen peroxide in the upper tropical troposphere over the Atlantic Ocean and western Africa during the CAFE-Africa aircraft campaign

Abstract 2 O2) in the upper tropical troposphere at altitudes between 8 and 15 km based on in situ observations during the Chemistry of the Atmosphere: Field Experiment in Africa (CAFE-Africa) campaign conducted in August–September 2018 over the tropical Atlantic Ocean and western Africa. The measured hydrogen peroxide mixing ratios in the upper troposphere show no clear trend in the latitudinal distribution with locally increased levels (up to 1 ppbv​​​​​​​) within the Intertropical Convergence Zone (ITCZ), over the African coastal area, as well as during measurements performed in proximity to the tropical storm Florence (later developing into a hurricane). The observed H2 O2 distribution suggests that mixing ratios in the upper troposphere seem to be far less dependent on latitude than assumed previously and the corresponding factors influencing the photochemical production and loss of H2 O2. The observed levels of H2 O2 in the upper troposphere indicate the influence of convective transport processes on the distribution of the species not only in the tropical but also in the subtropical regions. The measurements are compared to observation-based photostationary steady-state (PSS) calculations and numerical simulations by the global ECHAM/MESSy Atmospheric Chemistry (EMAC) model. North of the ITCZ, PSS calculations produce mostly lower H2 O2 mixing ratios relative to the observations. The observed mixing ratios tend to exceed the PSS calculations by up to a factor of 2. With the exception of local events, the comparison between the calculated PSS values and the observations indicates enhanced H2 O2 mixing ratios relative to the expectations based on PSS calculations in the north of the ITCZ. On the other hand, PSS calculations tend to overestimate the H2 O2 mixing ratios in most of the sampled area in the south of the ITCZ by a factor of up to 3. The significant influence of convection in the ITCZ and the enhanced presence of clouds towards the Southern Hemisphere indicate contributions of atmospheric transport and cloud scavenging in the sampled region. 2 O2 in the upper troposphere with a slight decrease from the ITCZ towards the subtropics, indicating a relatively low dependency on the solar radiation intensity and the corresponding photolytic activity. The largest model deviations relative to the observations correspond with the underestimated hydrogen peroxide loss due to enhanced cloud presence, scavenging, and rainout in the ITCZ and towards the south.

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch

References and Relationships

• Bibliographic citation: Measurement report: Hydrogen peroxide in the upper tropical troposphere over the Atlantic Ocean and western Africa during the CAFE-Africa aircraft campaign ; volume:23 ; number:10 ; year:2023 ; pages:5929-5943 ; extent:15 ; Atmospheric chemistry and physics ; 23, Heft 10 (2023), 5929-5943 (gesamt 15)

Contributors, Places and Time

• Creator: Hamryszczak, Zaneta ; Dienhart, Dirk ; Brendel, Bettina ; Rohloff, Roland ; Marno, Daniel ; Martinez, Monica ; Harder, Hartwig ; Pozzer, Andrea ; Bohn, Birger ; Zöger, Martin ; Lelieveld, Jos ; Fischer, Horst

Further information

• DOI: 10.5194/acp-23-5929-2023
• URN: urn:nbn:de:101:1-2023060104151723768283
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 14.08.2025, 10:49 AM CEST