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HOME > Monitoring_and_Data > Oceanic and Atmospheric Data > Reanalysis: Atmospheric Data > wgrib2-set_ens_num

wgrib2: -set_ens_num


The -set_ens_num option changes PDT 0,1 -> 1 and 8,11 -> 11. PDT 1 and 11 are for "forecasts from a specified member of an ensemble. Effectively this option add an "ensemble member ID" to the forecast.

With wgrib2 v3.1.1, more PDTs can be promoted to ensemble-member PDTs.

Merging ensembles, Adding New Members

When ensembles are made, each member has a unique perturbation/member number. When you want to merge ensembles, the member numbers may no longer be unique. You would want to renumber the forecasts sp that they would be unique. Sometimes you would want to add a forecast with no ensemble information; you need a way to add a ensemble member number.


-set_ens_num X Y Z
X = 0..255 type of ensemble member (Code Table 4.6)
Y = 0..255 perturbation number
Z = 0..255  number of forecasts in the ensemble


$ wgrib2 -set_ens_num 3 1 10 -grib ds_ens.grb
1:80:d=2009062918:DPT:surface:60 hour fcst:ENS=+1
2:218826:d=2009062918:DPT:surface:66 hour fcst:ENS=+1
3:434430:d=2009062918:DPT:surface:72 hour fcst:ENS=+1
4:652869:d=2009062918:DPT:surface:78 hour fcst:ENS=+1
5:871866:d=2009062918:DPT:surface:84 hour fcst:ENS=+1
6:1088694:d=2009062918:DPT:surface:90 hour fcst:ENS=+1
7:1304003:d=2009062918:DPT:surface:96 hour fcst:ENS=+1
8:1549304:d=2009062918:DPT:surface:102 hour fcst:ENS=+1

-set_ens_num 3 1 10
    3 = positive perturbed forecast
    1 = perturbation number
   10 = number of ensemble members

-grib ds_ens.grb
   save the new grib file in ds_ens.grb
See also: -set_ensm_derived_fcst, -ens, -N_ens

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Page last modified: May 15, 2005
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