Title
Simulation of tropospheric chemistry and aerosols with the climate model EC-Earth
Author
van Noije, T.P.C.
le Sager, P.
Segers, A.J.
van Velthoven, P.F.J.
Krol, M.C.
Hazeleger, W.
Williams, A.G.
Chambers, S.D.
Publication year
2014
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 oneway 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. © Author(s) 2014.
Subject
Earth / Environmental
CAS - Climate, Air and Sustainability
ELSS - Earth, Life and Social Sciences
Environment & Sustainability
Environment
Urbanisation
aerosol property
atmospheric chemistry
climate modeling
climatology
decadal variation
global climate
methane
optical depth
troposphere
vertical mixing
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DOI
https://doi.org/10.5194/gmd-7-2435-2014
TNO identifier
530269
Publisher
Copernicus GmbH
ISSN
1991-959X
Source
Geoscientific Model Development, 7 (5), 2435-2475
Document type
article