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Quantitative evaluation of ozone and selected climate parameters in a set of EMAC simulations

Righi, Mattia and Eyring, Veronika and Gottschaldt, Klaus-Dirk and Klinger, Carolin and Frank, Franziska and Jöckel, Patrick and Cionni, Irene (2015) Quantitative evaluation of ozone and selected climate parameters in a set of EMAC simulations. Geoscientific Model Development, 8 (3), pp. 733-768. Copernicus Publications. doi: 10.5194/gmd-8-733-2015. ISSN 1991-959X.

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Official URL: http://www.geosci-model-dev.net/8/733/2015/gmd-8-733-2015.html


Four simulations with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model have been evaluated with the Earth System Model Validation Tool (ESMValTool) to identify differences in simulated ozone and selected climate parameters that resulted from (i) different setups of the EMAC model (nudged vs. free-running) and (ii) different boundary conditions (emissions, sea surface temperatures (SSTs) and sea-ice concentrations (SICs)). To assess the relative performance of the simulations, quantitative performance metrics are calculated consistently for the climate parameters and ozone. This is important for the interpretation of the evaluation results since biases in climate can impact on biases in chemistry and vice versa. The observational datasets used for the evaluation include ozonesonde and aircraft data, meteorological reanalyses and satellite measurements. The results from a previous EMAC evaluation of a model simulation with weak nudging towards realistic meteorology in the troposphere have been compared to new simulations with different model setups and updated emission datasets in free-running timeslice and nudged Quasi Chemistry-Transport Model (QCTM) mode. The latter two configurations are particularly important for chemistry-climate projections and for the quantification of individual sources (e.g. transport sector) that lead to small chemical perturbations of the climate system, respectively. With the exception of some specific features which are detailed in this study, no large differences that could be related to the different setups of the EMAC simulations (nudged vs. free-running) were found, which offers the possibility to evaluate and improve the overall model with the help of shorter nudged simulations. The main differences between the two setups is a better representation of the tropospheric and stratospheric temperature in the nudged simulations, which also better reproduce stratospheric water vapour concentrations, due to the improved simulation of the temperature in the tropical tropopause layer. Ozone and ozone precursor concentrations on the other hand are very similar in the different model setups, if similar boundary conditions are used. Different boundary conditions however lead to relevant differences in the four simulations. SSTs and SICs, which are prescribed in all simulations, play a key role in the representation of the ozone hole, which is significantly underestimated in some experiments. A bias that is present in all simulations is an overestimation of tropospheric column ozone, which is significantly reduced when lower lightning emissions of nitrogen oxides are used. To further investigate possible other reasons for such bias, two sensitivity simulations with an updated scavenging routine and the addition of a newly proposed HNO3-forming channel of the HO2+ NO reaction were performed. The update in the scavenging routine resulted in a slightly better representation of ozone compared to the reference simulation. The introduction of the new HNO3-forming channel significantly reduces this bias. Therefore, including the new reaction rate could potentially be important for a realistic simulation of tropospheric ozone, although laboratory experiments and other models studies need to confirm this hypothesis and some modifications to the rate, which has a strong dependence on water vapour, might also still be needed.

Item URL in elib:https://elib.dlr.de/95715/
Document Type:Article
Title:Quantitative evaluation of ozone and selected climate parameters in a set of EMAC simulations
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Righi, MattiaDLR, IPAhttps://orcid.org/0000-0003-3827-5950UNSPECIFIED
Date:3 March 2015
Journal or Publication Title:Geoscientific Model Development
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 733-768
Publisher:Copernicus Publications
Keywords:Ozone, essential climate variables, climate-chemistry modelling, model evaluation
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Projekt ESMVal (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Earth System Modelling
Deposited By: Righi, Dr. Mattia
Deposited On:31 Mar 2015 14:32
Last Modified:28 Nov 2023 09:05

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