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Ensemble forecasts attempt to address the uncertain nature of NWP. Both initial condition errors and errors in the formulation of the physics forcing are compounded in NWP non-linear models degrading the accuracy of forecasts. The NCEP operational global ensemble model suite utilized a process called breeding (Toth et al. 1997) and later improved by use of the Ensemble Transform Bred Vector (http://www.emc.ncep.noaa.gov/gmb/ens/GEFS_Science_post.ppt) as a way to account for increase uncertainty from growing instabilities. The current system, effective 2007MAR, increased NAEFS (NCEP/GEFS) membership to 80 perturbations in cycling (see schematic plot http://www.emc.ncep.noaa.gov/gmb/ens/IMP_PLAN_final_post.ppt), replaced operational 56 perturbations in cycling 20 perturbed forecasts.