Stretched-grid Model Intercomparison Project: decadal regional climate simulations with enhanced variable and uniform-resolution GCMs

Variable-resolution GCMs using a global stretched-grid (SG) with enhanced resolution over the region(s) of interest is an established approach to regional climate modeling providing an efficient means for regional down-scaling to mesoscales. This approach has been used since the early-mid 90s by the French, U.S., Canadian, Australian and other climate modeling groups along with, or as an alternative to, the current widely-used nested-grid approach. Stretched-grid GCMs are used for continuous climate simulations as usual GCMs, with the only difference that variable-resolution grids are used instead of more traditional uniform grids. The important advantages of variable-resolution stretched-grid GCMs are that they do not require any lateral boundary conditions/forcing and are free of the associated undesirable computational problems. As a result, stretched-grid GCMs provide self-consistent interactions between global and regional scales while a high quality of global circulation is preserved, as in uniform-grid GCMs.