Representation of tropical deep convection in atmospheric models – Part 2: Tracer transport

Year: 2011

Authors: Hoyle C.R., Marécal V., Russo M.R., Allen G., Arteta J., Chemel C., Chipperfield M.P., D’Amato F., Dessens O., Feng W., Hamilton J.F., Harris N.R.P., Hosking J.S., Lewis A.C., Morgenstern O., Peter T., Pyle J.A., Reddmann T., Richards N.A.D., Telford P.J., Tian W., Viciani S., Volz-Thomas A., Wild O., Yang X., Zeng G.

Autors Affiliation: ETH, Inst Atmospher & Climate Sci, Zurich, Switzerland; Univ Oslo, Dept Geosci, N-0316 Oslo, Norway; Univ Leeds, Inst Climate & Atmospher Sci, Sch Earth & Environm, Leeds LS2 9JT, W Yorkshire, England; Univ Hertfordshire, NCAS Weather, Ctr Atmospher & Instrumentat Res, Hatfield AL10 9AB, Herts, England; Meteo France, Grp Etude Atmosphere Meteorol, Ctr Natl Rech Meteorol, Toulouse, France; Univ Lancaster, Lancaster Environm Ctr, Lancaster LA1 4YW, England; Univ Cambridge, Dept Chem, Ctr Atmospher Sci, NCAS Climate, Cambridge CB2 1TN, England; Karlsruhe Inst Technol, Inst Meteorol & Climate Res, Karlsruhe, Germany; Univ Cambridge, Dept Chem, European Ozone Res Coordinating Unit, Cambridge CB2 1EW, England; Univ Cambridge, Ctr Atmospher Sci, Cambridge, England; CNR INO Ist Nazl Ottica, I-650125 Florence, Italy; Univ York, York YO10 5DD, N Yorkshire, England; Forschungszentrum Julich, Inst Energy & Climate Res, D-52425 Julich, Germany; Univ Manchester, Ctr Atmospher Sci, Manchester, Lancs, England; CNRS, Toulouse, France

Abstract: The tropical transport processes of 14 different models or model versions were compared, within the framework of the SCOUT-O3 (Stratospheric-Climate Links with Emphasis on the Upper Troposphere and Lower Stratosphere) project. The tested models range from the regional to the global scale, and include numerical weather prediction (NWP), chemical transport, and chemistry-climate models. Idealised tracers were used in order to prevent the model’s chemistry schemes from influencing the results substantially, so that the effects of modelled transport could be isolated. We find large differences in the vertical transport of very short-lived tracers (with a lifetime of 6 h) within the tropical troposphere. Peak convective outflow altitudes range from around 300 hPa to almost 100 hPa among the different models, and the upper tropospheric tracer mixing ratios differ by up to an order of magnitude. The timing of convective events is found to be different between the models, even among those which source their forcing data from the same NWP model (ECMWF). The differences are less pronounced for longer lived tracers, however they could have implications for modelling the halogen burden of the lowermost stratosphere through transport of species such as bromoform, or short-lived hydrocarbons into the lowermost stratosphere. The modelled tracer profiles are strongly influenced by the convective transport parameterisations, and different boundary layer mixing parameterisations also have a large impact on the modelled tracer profiles. Preferential locations for rapid transport from the surface into the upper troposphere are similar in all models, and are mostly concentrated over the western Pacific, the Maritime Continent and the Indian Ocean. In contrast, models do not indicate that upward transport is highest over western Africa.

Journal/Review:

Volume: 11 (15)      Pages from: 8103  to: 8131

More Information: This work was supported with funding from the EU project SCOUT-O3. CRH was partly funded by SNSF grant number 200021_120175/1. NRPH thanks NERC for their Advanced Research Fellowship. NADR is funded via NERC NCEO. The CATT-BRAMS work was supported by the program LEFE/INSU in France (projects UTLS-tropicale and Tropopause 2009) and was performed using HPC resources of CINES under the allocation 2008-c2008012536 and 2009-c2009015036 made by GENCI (Grand Equipement National de Calcul Intensif). PJT was supported by NCEO (UK). We also thank NERC for funding the ACTIVE project and the NERC Airborne Research and Survey Facility (ARSF) for operational support of the Dornier-228 aircraft. Furthermore, the ACTIVE and SCOUT-O3 Tropical campaigns would not have been possible without the extensive support of the Australian Bureau of Meteorology, in particular Peter May at the Bureau of Meteorology Research Centre, Melbourne and Lori Chappel at the Regional Forecasting Centre in Darwin. We also thank the RAAF base, Darwin, for hosting the aircraft and campaign base, and for their logistical support.
KeyWords: atmospheric chemistry; atmospheric convection; atmospheric transport; climate modeling; halogen; outflow; parameterization; stratosphere; tracer; troposphere; weather forecasting, Africa; Indian Ocean
DOI: 10.5194/acp-11-8103-2011

Citations: 31
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