EMC: Info on the Ensemble forecasts using the Global Spectral Model
At NCEP the current operational ensemble configuration consists
of running:
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At 00Z each day (available through anonymous ftp from public servers):
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T254L64 high resolution control (file name for, e.g., a 24 hr fcst is: drfmr.T00Z.PGrbF24)
out to 7 days, after which this run gets truncated and is run out to 16
days at a T170L42 resolution
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T62 control that is started with a truncated T170 analysis ens.95021700.cnt.pgrb.f24
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10 perturbed forecasts each run at T62 horizontal resolution. The perturbations
are from five independent breeding cycles (See Toth and Kalnay, 1993, BAMS
and 1994, Preprints of 10th AMS Conference on Numerical Weather Prediction.)
Each perturbation is both added to: ens.95021700.p1.pgrb.f24, ens.95021700.p2.pgrb.f24,
etc, and subtracted from: ens.95021700.n1.pgrb.f24, ens.95021700.n2.pgrb.f24,
etc the control analysis.
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At 12Z:
-
T254L64 control out to 3 days (GFS forecast, formerly the Aviation), that gets truncated and
run at T170L42 resolution out to 16 days
-
Two pairs of perturbed forecasts based on two independent breeding cycles
(four perturbed integrations out to 16 days.)
The examples of files given above are pressure grib files, containing also
flux and surface related fields. For information and software on how to
read grib format files, using different platforms, click
here . If you would like to access the 12Z ensemble products (which
are currently not available on the nic), or if you have questions regarding
the ensemble forecasts you can contact:
Zoltan Toth Zoltan.Toth@noaa.gov
Lacey Holland Lacey.Holland@noaa.gov
