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Downscaling from Large to Small Spatial Scales

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    René Laprise Université du Québec à Montréal

Downscaling the results of large-scale, coupled, global models to relatively small spatial scales.

Owing to their huge computational load, global climate models must use coarse grids that prevent adequate resolution of several key regional processes. A common requirement of several MEOPAR projects is the need to downscale from global models to a regional/local scale. Dr. Laprise’s research centres on downscaling the results of large-scale, coupled, global models to relatively small spatial scales.

The interactive coupling of the current 5th-generation Canadian Regional Climate Model (CRCM5) with a regional ocean model constitutes a major leap forward in allowing interactions between the atmosphere and ocean over the Arctic and North Atlantic, thus improving the realism of climate simulations and projections over northern and eastern Canada. The resulting software will benefit a large Canadian community interested in climate-change impacts.

The Canadian Meteorological Centre (CMC) uses a version of NEMO, an ocean model developed through an international collaboration, coupled with their numerical weather prediction (NWP) system, using a smart and efficient coupler optimised for the CMC computing environment. The goal of this project was to port this software and adapt it for its use with CRCM5 for climate simulations and projections.

Porting the computer code of the coupler from the CMC computing environment to the Compute Canada supercomputer has proven a greater challenge than anticipated when the MEOPAR proposal was drafted. This is due to the highly specific design of the coupler that is optimised for NWP on the CMC computer. A new coupler, using some of the tools developed at CMC as well as new ones had to be developed. Mr. Michel Valin and Dr. Bernard Dugas, two numerical modelling specialists recently retired from ECCC, provided extremely valuable help and advice in adapting and implementing the software to the Compute Canada platform on which the CRCM5 and NEMO models have been tested in an off-line mode. The network approach of MEOPAR has secured the collaboration of BIO, UQAR and RPN in this endeavour.

In the meantime, much as been accomplished to document the added value of highresolution regional climate simulations. There has been collaboration with several international research groups by participating in the coordinated climate modelling project CORDEX, by performing CRCM5 simulations over several regions, including North America, Africa and Arctic. The analysis of CRCM5 hindcast simulations performed using grids of 0.44°, 0.22° and 0.11° over North America has established the considerable improvement afforded by the finest resolution for several regional climate phenomena. This has prompted OURANOS, the Consortium that performs high-resolution climate-change projections over North America using CRCM5, to switch their operations from 0.44° to 0.15°. All upgrades made to CRCM5 benefit to OURANOS and its community of users dealing with climate-change vulnerability, impact and adaptation (VIA); this is the main achievement, impact and socioeconomic outcome of this project.


  • Environment Canada
  • Fisheries and Oceans Canada - BIO - Maritimes


  • Pierre Dutrieux Université du Québec à Montréal
  • Philippe Lucas-Picher Université du Québec à Montréal
  • Maryam Takhsha Université du Québec à Rimouski


  • Lucas-Picher,Philippe ,F Boberg, J Christensens, P Berg . 2013, Dynamical Downscaling with Reinitializations: A method to generate fine- scale climate data sets suitable for impact studies, Journal of Hydrometeorology,
  • Laprise,René,Sushama,Laxshmi,. 2013, Reanalysis-driven Climate Simulations over CORDEX North America Domain using the Canadian Regional Climate Model, version 5, Clim. Dyn.,
  • Laprise,René,Matte, D., J. M. Thériault. 2016, Comparison between high-resolution climate simulations using single and double nesting within the Big-Brother experimental protocol., Clim. Dyn, pp 14,10.1007/s00382-016-3031-9.
  • Lucas-Picher,Philippe ,S Somot, M Deque, B Decharme, A Alias. 2013, Evaluation of the Regional Climate Model ALADIN to Simulate the Climate over North America in the CORDEX Framework, Climate Dynamics,
  • Laprise,René,Lucas-Picher,Philippe ,K. Winger. 2016, Evidence of added value in North American regional climate model simulations using ever-increasing horizontal resolutions, Climate Dynamics,
  • Laprise,René,Lucas-Picher,Philippe ,J. Cattiaux, A. Bougie. 2016, How does large-scale nudging in a regional climate model contribute to improving the simulation of weather regimes and seasonal extremes over North America?, Climate Dynamics, 46, 929-948,
  • Laprise,René,. 2013, Present Climate and Climate Change over North America as Simulated by the Fifth-Generation Canadian Regional Climate Model (CRCM5), Climate Dynamic,
  • Laprise,René,Di Luca, A., D. Argüeso, J.P. Evans, R. de Elía.. 2016, Quantifying the overall added value of dynamical downscaling and the contribution from different spatial scales., J. Geophys. Res. Atmos, 121(4), 1575-1590,10.1002/2015JD024009/full.
  • Laprise,René,Lucas-Picher,Philippe , P. Riboust, S. Somot,. 2015, Reconstruction of the spring 2011 Richelieu River flood by two regional climate models and a hydrological model, Journal of Hydrometeorology, 16, 36–54,
  • Laprise,René,Matte, D., and J. M. Thériault. 2016, Spatial spin-up of fine scales in a regional climate model simulation driven by low-resolution bound, Clim. Dyn., 12 pp.,
  • Laprise,René,Poan, D.E., P. Gachon, G. Dueymes, E.P. Diaconescu and I. Sanda Seidou. 2016, The West African monsoon intraseasonal activity and its daily precipitation indices in regional climate models: Diagnostics and challenges, Clim. Dyn, 10.1007/s00382-016-3016-8.