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Home > GFS Ensemble low resolution documentation

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.



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