Global Forecast System (GFS) Model Previous called the Aviation (AVN) and Medium Range Forecast (MRF) models. Spectral global model and 64 levels Relatively primitive microphysics. Sophisticated surface physics and radiation Run four times a day to 384 hr (16 days!). Major increase in skill during past decade derived from using direct satellite radiance in the 3DVAR analysis scheme. T574 (~27 km) over the first 192 hours (8 days) of the model forecast and T190 (70 km) for 180 through 384 hours--major implications for resolution change!

GFS Vertical coordinates are hybrid sigma/pressure… sigma at low levels to pressure aloft.

Vertical coordinate comparison across North America

GFS Data Assimilation Has a later data cut-off time than the mesoscale models…and thus can get a higher percentage of data. Uses much more satellite assets..thus improve global analysis and forecasts. Major gains in southern hemisphere Data assimilation based on 3DVAR (they call it GSI)

Skill Improvements (ECMWF) Useful skill until: - day 5 2000 - day 7 2003 - day 8

GFS