Simulation of tropospheric chemistry and aerosols with the climate model EC-Earth

T.P.C. van Noije, P. Le Sager, A.J. Segers, P.F.J. van Velthoven, M.C. Krol, W. Hazeleger, A.G. Williams, S.D. Chambers

Research output: Contribution to journalArticleAcademicpeer-review

30 Citations (Scopus)

Abstract

We have integrated the atmospheric chemistry and transport model TM5 into the global climate model EC-Earth version 2.4. We present an overview of the TM5 model and the two-way data exchange between TM5 and the IFS model from the European Centre for Medium-Range Weather Forecasts (ECMWF), the atmospheric general circulation model of EC-Earth. In this paper we evaluate the simulation of tropospheric chemistry and aerosols in a one-way coupled configuration. We have carried out a decadal simulation for present-day conditions and calculated chemical budgets and climatologies of tracer concentrations and aerosol optical depth. For comparison we have also performed offline simulations driven by meteorological fields from ECMWF's ERA-Interim reanalysis and output from the EC-Earth model itself. Compared to the offline simulations, the online-coupled system produces more efficient vertical mixing in the troposphere, which reflects an improvement of the treatment of cumulus convection. The chemistry in the EC-Earth simulations is affected by the fact that the current version of EC-Earth produces a cold bias with too dry air in large parts of the troposphere. Compared to the ERA-Interim driven simulation, the oxidizing capacity in EC-Earth is lower in the tropics and higher in the extratropics. The atmospheric lifetime of methane in EC-Earth is 9.4 years, which is 7% longer than the lifetime obtained with ERA-Interim but remains well within the range reported in the literature. We further evaluate the model by comparing the simulated climatologies of surface radon-222 and carbon monoxide, tropospheric and surface ozone, and aerosol optical depth against observational data. The work presented in this study is the first step in the development of EC-Earth into an Earth system model with fully interactive atmospheric chemistry and aerosols.
Original languageEnglish
Pages (from-to)2435-2475
JournalGeoscientific Model Development
Volume7
Issue number5
DOIs
Publication statusPublished - 2014

Keywords

  • intercomparison project accmip
  • general-circulation model
  • dry deposition parameterization
  • modified band approach
  • atmospheric chemistry
  • global-models
  • transport models
  • boundary-layer
  • stratospheric ozone
  • sulfur emissions

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