decadal regional climate simulations with enhanced variable and uniform-resolution GCMs

Springer-Verlag 2008SummaryVariable-resolution GCMs using a global stretched-grid(SG) with enhanced resolution over the region(s) of interestis an established approach to regional climate modelingproviding an efficient means for regional down-scaling tomesoscales. This approach has been used since the early-mid 90s by the French, U.S., Canadian, Australian andother climate modeling groups along with, or as an alter-native to, the current widely-used nested-grid approach.Stretched-grid GCMs are used for continuous climate simu-lations as usual GCMs, with the only difference that vari-able-resolution grids are used instead of more traditionaluniform grids. The important advantages of variable-reso-lution stretched-grid GCMs are that they do not require anylateral boundary conditions=forcing and are free of the as-sociated undesirable computational problems. As a result,stretched-grid GCMs provide self-consistent interactionsbetween global and regional scales while a high qualityof global circulation is preserved, as in uniform-grid GCMs.The international SGMIP-2 (Stretched-Grid Model Inter-comparison Project, phase-2) includes 25-year (1979–2003)climate simulations using enhanced variable and uniform-resolution GCMs developed at major centers=groups inAustralia, Canada, France, and the U.S. The SGMIP-2 re-gional (North American) and global products are availableas a link of the WMO=WCRP=WGNE web site: http:==collaboration.cmc.ec.gc.ca=science=wgne. The SGMIP-2multi-model regional ensembles compare well with reanaly-sis and observations, in terms of spatial and temporaldiagnostics. Regional biases are mostly limited to about half(or less) of typical observational or reanalysis errors while ahigh quality of global circulation is preserved. SGMIP-2 wasendorsed by the WMO=WCRP=WGNE at its annual meet-ings in 2004–2007.