EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Impact of in-cloud OVOC chemistry on tropospheric ozone

Simon Rosanka and Domenico Taraborrelli
Simon Rosanka and Domenico Taraborrelli
  • Institute of Energy and Climate Research, IEK-8: Troposphere, Forschungszentrum Jülich GmbH, Jülich, Germany

In-cloud aqueous-phase chemistry is known to decrease tropospheric ozone (O3) via O3+O2- with the major source of O2- being hydroperoxyl radicals (HO2). Therefore, tropospheric O3 is sensitive to aqueous-phase HOx (HOx=HO2+OH) chemistry. However, most global atmospheric models do not represent this sink reasonably well since they lack explicit representation of in-cloud aqueous-phase chemistry. In this study, a new detailed aqueous-phase mechanism for the oxidation of water soluble oxygenated volatile organic compounds (OVOCs) is developed, suitable for global scale modelling. This improves the representation of aqueous-phase HO2 and thus the removal of tropospheric O3. The mechanism focuses on OVOCs containing up to three-carbon atoms. A detailed box-model analysis under low and high NOx conditions is performed. Afterwards, the developed mechanism is implemented into the global atmospheric model ECHAM/MESSy (EMAC), which is capable to represent the described processes explicitly and integrates the corresponding ODE system with a Rosenbrock solver. EMAC is then used to estimate the global impact of the proposed mechanism with a focus on monsoon systems and biomass burning events. The implemented changes are evaluated using airborne campaign data like OMO for the Asian monsoon. The OVOC oxidation leads to an increase in ozone scavenging and a substantial reduction in tropospheric gas-phase chemical production of ozone. These changes in the free troposphere significantly reduce the modelled tropospheric ozone column, which is known to be overestimated by EMAC and global atmospheric models in general.

How to cite: Rosanka, S. and Taraborrelli, D.: Impact of in-cloud OVOC chemistry on tropospheric ozone, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10483,, 2020

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