The TOMCAT global chemical transport model v1.6: description of chemical mechanism and model evaluation

Monks, S. A.; Arnold, S. R.; Hollaway, Michael; Pope, Richard J.; Wilson, Chris; Feng, Wuhu; Emmerson, Kathryn M.; Kerridge, B. J.; Latter, Barry G.; Miles, Georgina; Siddans, Richard; Chipperfield, Martyn

doi:10.5194/gmd-10-3025-2017

Cited by 56 publications

(78 citation statements)

References 115 publications

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“…We performed a series of experiments with the TOMCAT/SLIMCAT 3-D CTM (Chipperfield, 2006;Monks et al, 2017), widely used in VSLS-related studies (e.g., Hossaini, Patra, et al, 2016, Hossaini, Chipperfield, et al, 2016. The CTM is forced by wind and temperature fields from the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis (Dee et al, 2011).…”

Section: Tomcat/slimcat 3-d Ctmmentioning

confidence: 99%

On the Regional and Seasonal Ozone Depletion Potential of Chlorinated Very Short‐Lived Substances

Hossaini

Wild

Chipperfield

et al. 2019

Geophysical Research Letters

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Chloroform (CHCl3), dichloromethane (CH2Cl2), perchloroethylene (C2Cl4), and 1,2‐dichloroethane (C2H4Cl2) are chlorinated Very Short‐Lived Substances (Cl‐VSLS) with a range of commercial/industrial applications. Recent studies highlight the increasing influence of Cl‐VSLS on the stratospheric chlorine budget and therefore their possible role in ozone depletion. Here we evaluate the ozone depletion potential (ODP) of these Cl‐VSLS using a three‐dimensional chemical transport model and investigate sensitivity to emission location/season. The seasonal dependence of the ODPs is small, but ODPs vary by a factor of 2–3 depending on the continent of emission: 0.0143–0.0264 (CHCl3), 0.0097–0.0208 (CH2Cl2), 0.0057–0.0198 (C2Cl4), and 0.0029–0.0119 (C2H4Cl2). Asian emissions produce the largest ODPs owing to proximity to the tropics and efficient troposphere‐to‐stratosphere transport of air originating from industrialized East Asia. The Cl‐VSLS ODPs are generally small, but the upper ends of the CHCl3 and CH2Cl2 ranges are comparable to the mean ODP of methyl chloride (0.02), a longer‐lived ozone‐depleting substance.

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Section: Tomcat/slimcat 3-d Ctmmentioning

confidence: 99%

On the Regional and Seasonal Ozone Depletion Potential of Chlorinated Very Short‐Lived Substances

Hossaini

Wild

Chipperfield

et al. 2019

Geophysical Research Letters

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“…It is used to study a range of chemistry-aerosol-transport issues in the troposphere (e.g. Monks et al, 2017) and stratosphere (e.g. Chipperfield et al, 2015).…”

Section: Tomcatmentioning

confidence: 99%

Age of air as a diagnostic for transport timescales in global models

et al. 2018

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Abstract. This paper presents the first results of an age-ofair (AoA) inter-comparison of six global transport models. Following a protocol, three global circulation models and three chemistry transport models simulated five tracers with boundary conditions that grow linearly in time. This allows for an evaluation of the AoA and transport times associated with inter-hemispheric transport, vertical mixing in the troposphere, transport to and in the stratosphere, and transport of air masses between land and ocean. Since AoA is not a directly measurable quantity in the atmosphere, simulations of 222 Rn and SF 6 were also performed. We focus this first analysis on averages over the period 2000-2010, taken from longer simulations covering the period 1988-2014. We find that two models, NIES and TOMCAT, show substantially slower vertical mixing in the troposphere compared to other models (LMDZ, TM5, EMAC, and ACTM). However, while the TOMCAT model, as used here, has slow transport between the hemispheres and between the atmosphere over land and ocean, the NIES model shows efficient horizontal mixing and a smaller latitudinal gradient in SF 6 compared to the other models and observations. We find consistent differences between models concerning vertical mixing of the troposphere, expressed as AoA differences and modelled 222 Rn gradients between 950 and 500 hPa. All models agree, however, on an interesting asymmetry in inter-hemispheric mixing, with faster transport from the Northern Hemisphere surface to the Southern Hemisphere than vice versa. This is attributed to a rectifier effect caused by a stronger seasonal cycle in boundary layer venting over Northern Hemispheric land masses, and possibly to a related asymmetric position of the intertropical convergence zone. The calculated AoA in the mid-upper stratosphere varies considerably among the models (4-7 years). Finally, we find that the inter-model differences are generally larger than differences in AoA that result from using the same model with a different resolution or convective parameterisation. Taken together, the AoA model inter-comparison provides a useful addition to traditional approaches to evaluate transport timescales. Results highlight that inter-model differences associated with resolved transport (advection, reanalysis data, nudging) and parameterised transport (convection, boundary layer mixing) are still large and require further analysis. For this purpose, all model output and analysis software are available.

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“…The TOMCAT global off-line CTM (Chipperfield, 2006) is forced by ECMWF ERA-Interim reanalysis meteorology (Dee et al, 2011) and has a horizontal spatial resolution of 2.8°× 2.8°with 31 vertical levels up to 10 hPa. The model includes detailed tropospheric chemistry, including 229 gas-phase reactions and 82 advected tracers (Monks et al, 2017), and heterogeneous chemistry driven by size-resolved aerosol from the GLOMAP module (Mann et al, 2010). Simulations used here include anthropogenic emissions from the Coupled Model Intercomparison Project Phase 6 (Hosely et al, 2018) and fire emissions from GFED vn4.0 (van der Werf et al, 2017).…”

Section: Tomcat Model Setup and Evaluationmentioning

confidence: 99%

Substantial Increases in Eastern Amazon and Cerrado Biomass Burning‐Sourced Tropospheric Ozone

Pope

Arnold

Chipperfield

et al. 2020

Geophysical Research Letters

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The decline in Amazonian deforestation rates and biomass burning activity (2001–2012) has been shown to reduce air pollutant emissions (e.g., aerosols) and improve regional air quality. However, in the Cerrado region (savannah grasslands in northeastern Brazil), satellite observations reveal increases in fire activity and tropospheric column nitrogen dioxide (an ozone precursor) during the burning season (August‐October, 2005–2016), which have partially offset these air quality benefits. Simulations from a 3‐D global chemistry transport model (CTM) capture this increase in NO2 with a surface increase of ~1 ppbv per decade. As there are limited long‐term observational tropospheric ozone records, we utilize the well‐evaluated CTM to investigate changes in ozone. Here, the CTM suggests that Cerrado region surface ozone is increasing by ~10 ppbv per decade. If left unmitigated, these positive fire‐sourced ozone trends will substantially increase the regional health risks and impacts from expected future enhancements in South American biomass burning activity under climate change.

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The TOMCAT global chemical transport model v1.6: description of chemical mechanism and model evaluation

Cited by 56 publications

References 115 publications

On the Regional and Seasonal Ozone Depletion Potential of Chlorinated Very Short‐Lived Substances

On the Regional and Seasonal Ozone Depletion Potential of Chlorinated Very Short‐Lived Substances

Age of air as a diagnostic for transport timescales in global models

Substantial Increases in Eastern Amazon and Cerrado Biomass Burning‐Sourced Tropospheric Ozone

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