Submitted as: development and technical paper 10 Nov 2021

Submitted as: development and technical paper | 10 Nov 2021

Review status: this preprint is currently under review for the journal GMD.

Multiphase processes in the EC-Earth Earth System model and their relevance to the atmospheric oxalate, sulfate, and iron cycles

Stelios Myriokefalitakis1, Elisa Bergas-Massó2,3, María Gonçalves-Ageitos2,3, Carlos Pérez García-Pando2,4, Twan van Noije5, Philippe Le Sager5, Akinori Ito6, Eleni Athanasopoulou1, Athanasios Nenes7,8, Maria Kanakidou9,10,7, Maarten C. Krol11,12, and Evangelos Gerasopoulos1 Stelios Myriokefalitakis et al.
  • 1Institute for Environmental Research and Sustainable Development (IERSD), National Observatory of Athens, Penteli, Greece
  • 2Barcelona Supercomputing Center (BSC), Barcelona, Spain
  • 3Universitat Politècnica de Catalunya (UPC), Barcelona, Spain
  • 4ICREA, Catalan Institution for Research and Advanced Studies, Barcelona, Spain
  • 5Royal Netherlands Meteorological Institute (KNMI), De Bilt, the Netherlands
  • 6Yokohama Institute for Earth Sciences, JAMSTEC, Yokohama, Japan
  • 7Institute for Chemical Engineering Sciences, Foundation for Research and Technology, Patras, Greece
  • 8School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
  • 9Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, Heraklion, Greece
  • 10Institute of Environmental Physics, University of Bremen, Bremen, Germany
  • 11Institute for Marine and Atmospheric Research (IMAU), Utrecht University, Utrecht, the Netherlands
  • 12Wageningen University, Wageningen, the Netherlands

Abstract. Understanding how multiphase processes affect the iron-containing aerosol cycle is key to predict ocean biogeochemistry changes and hence the feedback effects on climate. For this work, the EC-Earth Earth system model in its climate-chemistry configuration is used to simulate the global atmospheric oxalate (OXL), sulfate (SO42−), and iron (Fe) cycles, after incorporating a comprehensive representation of the multiphase chemistry in cloud droplets and aerosol water. The model considers a detailed gas-phase chemistry scheme, all major aerosol components, and the partitioning of gases in aerosol and atmospheric water phases. The dissolution of Fe-containing aerosols accounts kinetically for the solution’s acidity, oxalic acid, and irradiation. Aerosol acidity is explicitly calculated in the model, both for accumulation and coarse modes, accounting for thermodynamic processes involving inorganic and crustal species from sea salt and dust.

Simulations for present-day conditions (2000–2014) have been carried out with both EC-Earth and the atmospheric composition component of the model in standalone mode driven by meteorological fields from ECMWF’s ERA-Interim reanalysis. The calculated global budgets are presented and the links between the 1) aqueous-phase processes, 2) aerosol dissolution, and 3) atmospheric composition, are demonstrated and quantified. The model results are supported by comparison to available observations. We obtain an average global OXL net chemical production of 12.61 ± 0.06 Tg yr−1 in EC-Earth, with glyoxal being by far the most important precursor of oxalic acid. In comparison to the ERA-Interim simulation, differences in atmospheric dynamics as well as the simulated weaker oxidizing capacity in EC-Earth result overall in a ~30 % lower OXL source. On the other hand, the more explicit representation of the aqueous-phase chemistry in EC-Earth compared to the previous versions of the model leads to an overall ~20 % higher sulfate production, but still well correlated with atmospheric observations.

The total Fe dissolution rate in EC-Earth is calculated at 0.806 ± 0.014 Tg Fe yr−1 and is added to the primary dissolved Fe (DFe) sources from dust and combustion aerosols in the model (0.072 ± 0.001 Tg Fe yr−1). The simulated DFe concentrations show a satisfactory comparison with available observations, indicating an atmospheric burden of ∼0.007 Tg Fe, and overall resulting in an atmospheric deposition flux into the global ocean of 0.376 ± 0.005 Tg Fe yr−1, well within the range reported in the literature. All in all, this work is a first step towards the development of EC-Earth into an Earth System Model with fully interactive bioavailable atmospheric Fe inputs to the marine biogeochemistry component of the model.

Stelios Myriokefalitakis et al.

Status: open (until 05 Jan 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CEC1: 'Comment on gmd-2021-357', Juan Antonio Añel, 26 Nov 2021 reply

Stelios Myriokefalitakis et al.

Stelios Myriokefalitakis et al.


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Short summary
We here describe the implementation of atmospheric multiphase processes in the EC-Earth Earth system model. We provide global budgets of oxalate, sulfate, and iron-containing aerosols along with an analysis of the links among atmospheric composition, aqueous-phase processes, and aerosol dissolution, supported by comparison to observations. This work is a first step towards an interactive calculation of the deposition of bioavailable atmospheric iron coupled to the model’s ocean component.