Numerical Forecast Systems
Info on the Ensemble forecasts using the Global Spectral Model
Global EPS Report to WMO on NCEP Global Ensemble Forecast System (GEFS) pdf
At NCEP the current NCEP Global Ensemble configuration consists of runs at 00Z, 06Z, 12Z 18Z each day (available through anonymous ftp from public servers)
Three different types of forecast files are generated from each run:
A T382L64 high resolution control (file name for, e.g., a 24 hr fcst at 00Z is gfs.t00z.pgrbf24) out to 7 days, after which this run gets truncated and is run out to 16 days at a T126L64 resolution
A T190L28 control that is started with a truncated T382L64 analysis and run out to 16 days, labeled as (gec00.t00z.pgrb(a/b)f24)
20 perturbed forecasts each run out to 16 days at T190L28 horizontal and vertical resolution. The initial perturbations are generated using Ensemble Transform with Rescaling (ETR) method**. Each perturbed forecast will be labled as gep(01/02/03...).t00z.pgrb(a/b)f24
The examples of files given above are pressure grib files that also contain flux and surface related fields. For information and software on how to read grib format files, using different platforms, click here . If you have questions regarding the ensemble forecasts you can contact Yuejian Zhu at Yuejian.Zhu@noaa.gov
**(See Wei et al., 2007; Initial perturbations based on the ensemble transform (ET) technique in the NCEP global operational forecast system; Tellus)