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I downloaded data from the american gfs weather modell (from ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.2014101812/master, edit date if you read more than 1 month later). Those are grib-files.

I am using grads to plot data and it works fine if I plot data from 1 timestep (=1 file) on a map. So my first try was to open the first 2 files and to make a shaded plot showing areas with the same wind speed in the same color. What I get is an empty plot with correct axes.

'open gfs.t12z.mastergrb2f00.ctl'

'open gfs.t12z.mastergrb2f03.ctl'

'set dfile 1'

'set time 12Z17OCT2014'
'set gxout shaded'
'set lat 50'
'set lon 0'
'set lev 1000 200'
'set t 1 2'
'd sqrt(ugrdprs*ugrdprs+vgrdprs*vgrdprs)*1.9438'

'set dfile 2'
'set time 15Z17OCT2014'
'set t 1 2'
'd sqrt(ugrdprs*ugrdprs+vgrdprs*vgrdprs)*1.9438'

I am using opengrads – Grid Analysis and Display System (GrADS) Version 2.0.2.oga.2.

Anyone who can help me plotting data from different timesteps (= different files) into one plot?

Dremet
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1 Answers1

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You can use one .ctl file to plot multiple data files. I have done this with .gdat files, so I guess you will be able to do it with GRIB. You should make new .ctl file using grads templates.

http://www.iges.org/grads/gadoc/templates.html

Basically, in dset line you will put a file name similar to 

dset gfs.t12z.mastergrb2f%h2.grb

where %h2 represents 2 digit hour.

luka
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