A Strategy for Process-Oriented Validation of Coupled Chemistry–Climate Models

Eyring, Veronika; Harris, Neil; Rex, Markus; Shepherd, T. G.; Fahey, D. W.; Amanatidis, G. T.; Austin, J.; Chipperfield, Martyn P.; Dameris, Martin; Forster, Piers M.; Gettelman, Andrew; Graf, Hans F.; Nagashima, Tatsuya; Newman, Paul A.; Pawson, S.; Prather, Michael J.; Pyle, J. A.; Salawitch, R. J.; Santer, Benjamin D.; Waugh, Darryn W.

doi:10.1175/bams-86-8-1117

Cited by 153 publications

(122 citation statements)

References 87 publications

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“…The model has 66 vertical levels from the ground to 5.96 × 10 −6 hPa, and shows good performance in simulating stratospheric processes (cf. Eyring et al, 2005;. Further details regarding the model can be found in Garcia et al (2007).…”

Section: Model and Numerical Experimentsmentioning

confidence: 99%

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Tian

Xie

et al. 2014

Adv. Atmos. Sci.

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Article:Hu, D, Tian, W, Xie, F et al. (2 more authors) (2014) Effects of meridional sea surface temperature changes on stratospheric temperature and circulation. Advances in Atmospheric Sciences, 31 (4). 888 -900. ISSN 0256-1530 https://doi.org/10.1007/s00376-013-3152-6 eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. ABSTRACT Using a state-of-the-art chemistry-climate model, we analyzed the atmospheric responses to increases in sea surface temperature (SST). The results showed that increases in SST and the SST meridional gradient could intensify the subtropical westerly jets and significantly weaken the northern polar vortex. In the model runs, global uniform SST increases produced a more significant impact on the southern stratosphere than the northern stratosphere, while SST gradient increases produced a more significant impact on the northern stratosphere. The asymmetric responses of the northern and southern polar stratosphere to SST meridional gradient changes were found to be mainly due to different wave properties and transmissions in the northern and southern atmosphere. Although SST increases may give rise to stronger waves, the results showed that the effect of SST increases on the vertical propagation of tropospheric waves into the stratosphere will vary with height and latitude and be sensitive to SST meridional gradient changes. Both uniform and non-uniform SST increases accelerated the large-scale Brewer-Dobson circulation (BDC), but the gradient increases of SST between 60 • S and 60 • N resulted in younger mean age-of-air in the stratosphere and a larger increase in tropical upwelling, with a much higher tropopause than from a global uniform 1.0 K SST increase.

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Section: Model and Numerical Experimentsmentioning

confidence: 99%

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Tian

Xie

et al. 2014

Adv. Atmos. Sci.

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“…In the meantime, multi-model experiments were performed with global climate-chemistry models (CCMs) and chemistry transport models (CTMs) to better assess the past and future evolution of the atmospheric composition under anthropogenic emission evolution as well as climate change: PHOTOCOMP for tropospheric chemistry Stevenson et al 2006;Dentener et al 2006a), CCMVal for stratospheric ozone (Eyring et al 2005(Eyring et al , 2006(Eyring et al , 2007SPARC 2010) and AeroCom for aerosols Schulz et al 2006). Such climate-chemistry models solely consider atmospheric circulation and include a more or less detailed representation of atmospheric chemistry.…”

Section: Introductionmentioning

confidence: 99%

Aerosol and ozone changes as forcing for climate evolution between 1850 and 2100

et al. 2012

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Global aerosol and ozone distributions and their associated radiative forcings were simulated between 1850 and 2100 following a recent historical emission dataset and under the representative concentration pathways (RCP) for the future. These simulations were used in an Earth System Model to account for the changes in both radiatively and chemically active compounds, when simulating the climate evolution. The past negative stratospheric ozone trends result in a negative climate forcing culminating at -0.15 W m -2 in the 1990s. In the meantime, the tropospheric ozone burden increase generates a positive climate forcing peaking at 0.41 W m -2 . The future evolution of ozone strongly depends on the RCP scenario considered. In RCP4.5 and RCP6.0, the evolution of both stratospheric and tropospheric ozone generate relatively weak radiative forcing changes until 2060-2070 followed by a relative 30 % decrease in radiative forcing by 2100. In contrast, RCP8.5 and RCP2.6 model projections exhibit strongly different ozone radiative forcing trajectories. In the RCP2.6 scenario, both effects (stratospheric ozone, a negative forcing, and tropospheric ozone, a positive forcing) decline towards 1950s values while they both get stronger in the RCP8.5 scenario. Over the twentieth century, the evolution of the total aerosol burden is characterized by a strong increase after World War II until the middle of the 1980s followed by a stabilization during the last decade due to the strong decrease in sulfates in OECD countries since the 1970s. The cooling effects reach their maximal values in 1980, with -0.34 and -0.28 W m -2 respectively for direct and indirect total radiative forcings. According to the RCP scenarios, the aerosol content, after peaking around 2010, is projected to decline strongly and monotonically during the twenty-first century for the RCP8.5, 4.5 and 2.6 scenarios. While for RCP6.0 the decline occurs later, after peaking around 2050. As a consequence the relative importance of the total cooling effect of aerosols becomes weaker throughout the twenty-first century compared with the positive forcing of greenhouse gases. Nevertheless, both surface ozone and aerosol content show very different regional features depending on the future scenario considered. Hence, in 2050, surface ozone changes vary between -12 and ?12 ppbv over Asia depending on the RCP projection, whereas the regional direct aerosol radiative forcing can locally exceed -3 W m -2 . This paper is a contribution to the special issue on the IPSL and CNRM global climate and Earth System Models, both developed in France and contributing to the 5th coupled model intercomparison project.Electronic supplementary material The online version of this article

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“…Within the GRIPS (GCM Intercomparison for SPARC, Stratospheric Processes and their Role in Climate) project, the first intercomparison of middle atmosphere GCMs showed a general cold bias in the global averaged temperature (Pawson et al, 2000), indicative of systematic uncertainties in the radiative transfer parameterizations used in the models. More recently, the evaluation of radiative parameterizations employed in GCMs that include the stratosphere is part of the Chemistry Climate Model Validation (CCMVAL, Eyring et al, 2005) project. The main purposes of this work are to improve the representation of the ozone absorption in the stratosphere of the MAECHAM5 middle atmosphere GCM (Manzini et al, 2006), and to evaluate its impact on the simulated mean temperature.…”

Section: Introductionmentioning

confidence: 99%

Impact of an improved shortwave radiation scheme in the MAECHAM5 General Circulation Model

et al. 2007

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Abstract. In order to improve the representation of ozone absorption in the stratosphere of the MAECHAM5 general circulation model, the spectral resolution of the shortwave radiation parameterization used in the model has been increased from 4 to 6 bands. Two 20-years simulations with the general circulation model have been performed, one with the standard and the other with the newly introduced parameterization respectively, to evaluate the temperature and dynamical changes arising from the two different representations of the shortwave radiative transfer. In the simulation with the increased spectral resolution in the radiation parameterization, a significant warming of almost the entire model domain is reported. At the summer stratopause the temperature increase is about 6 K and alleviates the cold bias present in the model when the standard radiation scheme is used. These general circulation model results are consistent both with previous validation of the radiation scheme and with the offline clear-sky comparison performed in the current work with a discrete ordinate 4 stream scattering line by line radiative transfer model. The offline validation shows a substantial reduction of the daily averaged shortwave heating rate bias (1-2 K/day cooling) that occurs for the standard radiation parameterization in the upper stratosphere, present under a range of atmospheric conditions. Therefore, the 6 band shortwave radiation parameterization is considered to be better suited for the representation of the ozone absorption in the stratosphere than the 4 band parameterization. Concerning the dynamical response in the general circulation model, it is found that the reported warming at the summer stratopause induces stronger zonal mean zonal winds in the middle atmosphere. These stronger zonal mean zonal winds thereafter appear to produce a dynamical feedback that results inCorrespondence to: C. Cagnazzo (cagnazzo@bo.ingv.it) a dynamical warming (cooling) of the polar winter (summer) mesosphere, caused by an increased downward (upward) circulation in the winter (summer) hemisphere. In addition, the comparison of the two simulations performed with the general circulation model shows that the increase in the spectral resolution of the shortwave radiation and the associated changes in the cloud optical properties result in a warming (0.5-1 K) and moistening (3%-12%) of the upper tropical troposphere. By comparing these modeled differences with previous works, it appears that the reported changes in the solar radiation scheme contribute to improve the model mean temperature also in the troposphere.

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A Strategy for Process-Oriented Validation of Coupled Chemistry–Climate Models

Cited by 153 publications

References 87 publications

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Effects of meridional sea surface temperature changes on stratospheric temperature and circulation

Aerosol and ozone changes as forcing for climate evolution between 1850 and 2100

Impact of an improved shortwave radiation scheme in the MAECHAM5 General Circulation Model

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