Global Forecast System (GFS) Model

• Previous called the Aviation (AVN) and Medium Range Forecast (MRF) models.

• Global model and 64 levels• Relatively primitive microphysics.• Sophisticated surface physics and radiation• Run four times a day to 384 hr.• Major increase in skill during past five years 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!

GFS

• Just changed vertical coordinates from sigma to 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

• Based on 3DVAR

CDAS/Reanl vs GFSNH/SH 500Hpa day 5

Anomaly Correlation (20-80 N/S)

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1960 1970 1980 1990 2000

YEAR

Anomaly Correlation

NH GFS

SH GFS

NH CDAS/Reanl

SH CDAS/Reanl

Skill Improvements (ECMWF)

Useful skill until:

1980 - day 5

2000 - day 7

2003 - day 8

Rapid Update Cycle-RUC

RUC• A major issue is how to assimilate and use the

rapidly increasing array of offtime or continuous observations (not a 00 and 12 UTC world anymore!

• Want very good analyses and very good short-term forecasts (1-3-6 hr)

• The RUC ingests and assimilates data hourly, and then makes short-term forecasts

• Uses the MAPS mesoscale model…which uses a hybrid sigma/isentropic vertical coordinate

• Resolution: 13 km and 50 levels

13km RUC

Improvements expected from 13km RUC- Improved near-surface forecasts- Improved precipitation forecasts- Better cloud/icing depiction- Improved frontal/turbulence forecasts

Terrain elevation - 100 m interval

NCEP computer upgrade allows RUC13 to run in same time as current RUC20

Observations used in RUCData Type ~Number Freq.--------------------------------------------------Rawinsonde 80 /12hNOAA profilers 30 / 1hVAD winds 110-130 / 1h Aircraft (V,temp) 1400-4500 / 1hSurface/METAR 1500-1700 / 1hSurface/METAR 1500-1700 / 1hBuoy/ship 100-150 / 1hGOES precip water 1500-3000 / 1hGOES cloud winds 1000-2500 / 1hGOES cloud-top pres 10 km res / 1hSSM/I precip water 1000-4000 / 6h--------------------------------------------------GPS precip water ~300 / 1hMesonet ~5000 / 1hMETAR-cloud-vis-wx ~1500 / 1h--------------------------------------------------

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RUC13

(at NCEP June 2005)

Cloudanalysisvariables

RUC History – NCEP (NMC) implementations

1994 - First operational implementation of RUC- 60km resolution, 3-h cycle

1998 – 40km resolution, 1-h cycle, - cloud physics, land-sfc model

2002 – 20km resolution- addition of GOES cloud data in assimilation

2003 – Change to 3dVAR analysis from previous OI(April)

2004 – Vertical advection, land use (April)PBL-depth for surface assimilation

(September)

2005 – 13km resolution, new obs, new model physics(June)

2007 – WRF-based Rapid Refresh w/ GSI to replace RUC

More detailed coastline with 13km resolution

13km RUC 20km RUC

Soil moisture – 22z - 21 Feb 2005Dark blue = water

WRF RUC

• A new version of RUC has been developed, but not yet operational that uses the WRF model instead of the MAPS model.