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Off-Line Algorithm for Calculation of Vertical Tracer Transport in The EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Natural Hazards Natural Hazards and Earth System and Earth System Sciences Sciences Discussions Open Access Open Access Atmos. Chem. Phys., 13, 1093–1114, 2013 Atmospheric Atmospheric www.atmos-chem-phys.net/13/1093/2013/ doi:10.5194/acp-13-1093-2013 Chemistry Chemistry © Author(s) 2013. CC Attribution 3.0 License. and Physics and Physics Discussions Open Access Open Access Atmospheric Atmospheric Measurement Measurement Techniques Techniques Off-line algorithm for calculation of vertical tracer transport in the Discussions Open Access troposphere due to deep convection Open Access Biogeosciences 1,2 1 3,4,5 6 7 8 Biogeosciences9 10 D. A. Belikov , S. Maksyutov , M. Krol , A. Fraser , M. Rigby , H. Bian , A. Agusti-Panareda , D. Bergmann , Discussions P. Bousquet11, P. Cameron-Smith10, M. P. Chipperfield12, A. Fortems-Cheiney11, E. Gloor12, K. Haynes13,14, P. Hess15, S. Houweling3,4, S. R. Kawa8, R. M. Law14, Z. Loh14, L. Meng16, P. I. Palmer6, P. K. Patra17, R. G. Prinn18, R. Saito17, 12 Open Access and C. Wilson Open Access 1Center for Global Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa,Climate Tsukuba, Ibaraki, Climate 305-8506, Japan of the Past 2 of the Past Division for Polar Research, National Institute of Polar Research, 10-3, Midoricho, Tachikawa, Tokyo 190-8518, Japan Discussions 3SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands 4Institute for Marine and Atmospheric Research Utrecht (IMAU), Princetonplein 5, 3584 CC Utrecht, The Netherlands Open Access 5 Open Access Wageningen University and Research Centre, Droevendaalsesteeg 4, 6708 PB Wageningen, The Netherlands Earth System 6School of GeoSciences, University of Edinburgh, King’s Buildings, West Mains Road, Edinburgh,Earth EH9System 3JN, UK 7School of Chemistry University of Bristol Bristol, UK Dynamics 8 Dynamics Goddard Earth Sciences and Technology Center, NASA Goddard Space Flight Center, Code 613.3, Greenbelt, MD 20771, Discussions USA 9ECMWF, Shinfield Park, Reading, Berks, RG2 9AX, UK Open Access 10Atmospheric, Earth, and Energy Division, Lawrence Livermore National Laboratory, 7000 EastGeoscientific Avenue, Livermore, Geoscientific Open Access CA94550, USA Instrumentation Instrumentation 11 Universite de Versailles Saint Quentin en Yvelines (UVSQ), GIF sur YVETTE, France Methods and Methods and 12Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK 13Department of Atmospheric Science, Colorado State University, Fort Collins, CO, 80523,Data USA Systems Data Systems 14Centre for Australian Weather and Climate Research, CSIRO Marine and Atmospheric Research, 107-121 Station St., Discussions Open Access Open Access Aspendale, VIC 3195, Australia Geoscientific 15Cornell University, 2140 Snee Hall, Ithaca, NY 14850, USA Geoscientific 16Department of Geography and Environmental Studies Program, Western Michigan University, Kalamazoo, MI 49008, USA Model Development 17 Model Development Research Institute for Global Change/JAMSTEC, 3173-25 Showa-machi, Yokohama, 236-0001, Japan Discussions 18Center for Global Change Science, Building 54, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA Open Access Open Access Correspondence to: D. A. Belikov ([email protected]) Hydrology and Hydrology and Received: 25 May 2012 – Published in Atmos. Chem. Phys. Discuss.: 14 August 2012 Earth System Earth System Revised: 11 January 2013 – Accepted: 14 January 2013 – Published: 1 February 2013 Sciences Sciences Discussions Open Access Abstract. A modified cumulus convection parametrisation 25/JCDAS reanalysis. The simulated convectiveOpen Access precipita- scheme is presented. This scheme computes the mass of air tion rate and mass fluxes are compared with observations Ocean Science transported upward in a cumulus cell using conservation of and reanalysis data. AOcean simulation Science of the short-lived tracer moisture and a detailed distribution of convective precipi- 222Rn is used to further evaluate the performance of the cu- Discussions tation provided by a reanalysis dataset. The representation mulus convection scheme. Simulated distributions of 222Rn of vertical transport within the scheme includes entrainment are evaluated against observations at the surface and in the Open Access and detrainment processes in convective updrafts and down- free troposphere, and compared with output fromOpen Access models that drafts. Output from the proposed parametrisation scheme is participated in the TransCom-CH4 Transport Model Inter- Solid Earth employed in the National Institute for Environmental Stud- comparison. From this comparison,Solid we Earth demonstrate that the Discussions ies (NIES) global chemical transport model driven by JRA- Open Access Open Access Published by Copernicus Publications on behalf of the European Geosciences Union. The Cryosphere The Cryosphere Discussions 1094 D. A. Belikov et al.: Off-line algorithm for calculation of vertical tracer transport proposed convective scheme in general is consistent with ob- The options available for on-line CTMs are generally not served and modeled results. available for off-line models, which are operated using a limited set of time-averaged, predefined meteorological pa- rameters taken from a gridded reanalysis dataset. Reanaly- 1 Introduction sis datasets often do not contain all fields that are necessary for tracer transport modelling, such as parameters associated Deep cumulus convection (DCC) plays an important role in with subgrid-scale mixing; consequently, the implementation the hydrological cycle of the climate system, the dynamics of of parametrisation schemes in off-line CTMs presents a sig- the atmospheric circulation and the transport of trace gases nificant challenge (Mahowald et al., 1995, 1997). within the troposphere. Indeed, the major sources of uncer- Previous studies have demonstrated that transport model tainty in climate models are associated with the representa- simulations of the distribution of 222Rn fields are strongly tion of cumulus convection. DCC also affects atmospheric sensitive to the parametrisation used to represent cumulus chemistry indirectly through latent heating and contributions convection (Brost and Chatfield, 1989; Jacob et al., 1997). to the budgets of solar and infrared radiation (Lawrence and 222Rn is almost completely insoluble in water, so that it is re- Salzmann, 2008). moved from the atmosphere solely by radioactive decay. The Deep convective updrafts extend from the surface to the sensitivity to the parametrisation schemes and the relatively upper troposphere, with typical vertical velocities of several simple life cycle make 222Rn an excellent tracer for evalu- meters per second. These rapid updrafts are accompanied by ating the performance of transport models in simulations of rapid downdrafts, which together result in considerable verti- short-range transport over continental and remote oceanic re- cal mixing and deliver polluted boundary layer air to the mid- gions (Allen et al., 1996; Dentener et al., 1999). dle and upper troposphere (Feichter and Crutzen, 1990). Air Although 222Rn has long been recognized as a useful masses associated with DCC can reach altitudes above the tracer for evaluating the performance of transport models, zero radiative heating level in the tropical tropopause layer, it has several disadvantages related to source uncertainties. allowing detrained air to slowly ascend into the lower strato- The most frequently used fluxes (Jacob et al., 1997) are ac- sphere (Folkins et al., 1999; Fueglistaler et al., 2004). The curate to within 25 % globally and to within a factor of two rapid updrafts associated with DCC occasionally even cause regionally. The main factors controlling spatial variations in direct penetration of tropospheric air into the lower strato- 222Rn flux are depth of aerated soil, soil 226Ra concentrations sphere, which can last up to several hours. After rapid ascent (222Rn precursor) and emanation rate. The main factors de- from the surface layer in DCC, tracers can be advected over termining temporal variations are precipitation and soil mois- long distances by the strong zonal winds that prevail in the ture. Shallow water tables and frost cover can be a cause of upper troposphere (Allen et al., 1996; Zaucker et al., 1996). temporal but also of spatial variation (Conen, 2004). This relationship illustrates the important role that convec- Previous studies have performed detailed examinations of tion plays in long-range tracer transport. Along with large- the influence of convective mixing on 222Rn and other short- scale advection and vertical diffusion, cumulus convection is lived tracers’ distributions in the troposphere (Mahowald et one of the most important transport processes affecting at- al., 1995, 1997; Allen et al., 1996; Li and Chang, 1996; Ja- mospheric tracers. cob et al., 1997; Rasch et al., 1997; Stockwell et al., 1998; General circulation models (GCMs) and chemical trans- Olivie´ et al., 2004; Zhang at el., 2008). Although measure- port models (CTMs) are unable to explicitly resolve convec- ments of atmospheric radon concentration by distributed ob- tion due to its small spatial scale relative to synoptic-scale servatories provide good reference points for model evalua- processes and the resolution
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