• 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 .
• T382 (~35 km) over the first 180 hours (7.5 days) of the model forecast and T190 (70 km) for 180 through
384 hours--major implications for resolution change!

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

Vertical coordinate comparison across North America

• 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)

90
85
80
75
70
65
60
55
50
45
40
1960 1970
CDAS/Reanl vs GFS
NH/SH 500Hpa day 5
Anomaly Correlation (20-80 N/S)
NH GFS
SH GFS
NH CDAS/Reanl
SH CDAS/Reanl
1980
YEAR
1990 2000

Useful skill until:
1980 - day 5
2000 - day 7
2003 - day 8