-set_metadata¶
Introduction¶
Whenever -set_metadata option is "executed", one line of the data file is read, the metadata is then applied to the current (sub-)message. For example, your grib file has 3 messages and you want to alter the metadata. Here is a metadata file that could be used to alter the grib file.
0:0:d=2009010100:HGT:500 mb:anl:scale=0,0:
0:0:d=2009010100:TMP:2 m above ground:anl
0:0:d=2009010106:HGT:500 mb:12 hour forecast:scale=0,0
The format of the metadata file resembles the wgrib2 inventory by design. The first and second fields are ignored by by -set_metadata. In practice, the first first is the record number and the second field is the byte location of the template to be used. (A template file could be a collection of templates.) The third through sixth fields are the date code, variable name, level and ftime. Finally the remaining fields are optional and order independent.
The date field has been extended from the default d=YYYYMMDDHH. The date field can be d=format-N or D=format-N
Format 1
YYYY, YYYYMM, YYYYMMDD, YYYYMMDDHH, YYYYMMDDHHmm or YYYYMMDDHHmmss
where YYYY = 4 digit year
MM = 2 digit month
DD = 2 digit day of month
mm = 2 digit minute
ss = 2 digit second
If MM, DD, mm, ss are missing, the values are unchanged.
Format 2
+N(units) N is an integer, units = hr, dy, mo or yr
this adds N units to the reference time
ex. +6hr, +1dy
Format 3
-N(units) N is an integer, units = hr, dy, mo or yr
this subtracts N units to the reference time
ex. -6hr, -1dy
Optional fields
scale=I,J set decimal scaling (I) and binary scaling (J) for encoding
encode i*2^J*10^I set decimal scaling (I) and binary scaling (J) for encoding
same as scale=I,J v2.0.6+
encode I bits store grid values using I bits, no decimal scaling (ECMWF style) v2.0.6+
grib_max_bits=I set maximum number of bits used to store grid point data (max 25) v2.0.6+
packing=S set compression/packing to S
S=simple,complex1,complex2,complex3,jpeg,aec (long form)
S=s,c1,c2,c3,j (short form)
N%d level set percentile
prob ... set probability
XYZ XYZ=ens mean, wt ens mean, ens std dev, cluster std dev, normalized ens std dev,
normalizedd cluster std dev, ens spread, ens large anom index, wt ens mean,
unwt custer mean, 25%-75% range, min all members, max all members
ENS=... set ensemble member info
ENS=hi-res, low-res, +N, or -N
N ens members set number of ensemble members
ex. 22 ens members
code table X.Y=Z set code table, equivalent -set table_X.Y Z requires wgrib2 v2.0.5+
flag table X.Y=Z set flag table, equivalent -set table_X.Y Z requires wgrib2 v2.0.5+
note: not all X.Y have been implemented
Following options follows -set VAR VAL and do not follow the wgrib2 inventory format
disciple=
local_table=
master_table=
center= set center
subcenter= set sub-center
background_process_id=
analysis_or_forecast_process_id=
table_M.N= only for selected M.N
To change the metadata, you can do
wgrib2 in.grb -s >meta
(change meta)
wgrib2 in.grb -set_metadata meta -grib out.grb
Note: that -grib does not change the grid point data/packing.
The -set_metadata option is used for creating grib2 files. Note that both -set_metadata and the various -import options will change the output precision. Consequently the -import option should preceed the -set_metadatda option.
Note: only a subset of levels and ftime parameters is currently implemented. The -set_metadatda option does not support all metadata.
To format of the levels and ftime are the same was used by wgrib2 inventories.
See also: -set_ave, -set_date, -set_ftime, -set_lev, -set_metadata_str, -set_scale, set_var,
Description: misc X read meta-data for grib writing from file X
Docs derived from https://www.cpc.ncep.noaa.gov/products/wesley/wgrib2/set_metadata.html