[gradsusr] GFS plotting data from different files (different points of time) in one 2D (height – time) plot

[Jeff Duda]

Andre,
It looks like you have the right idea, but I don't see a reason for the
commands

'set t 1 2'

That will cause grads to plot two different time steps worth of data.
Based on my knowledge of those GFS files, there is only one time slice of
data in each file, so depending on what the TDEF line of your control file
says, you should get an error on the second time slice.  Also, Grads does
not overlay plots that vary in time, only plots that are fixed in any two
dimensions (X-Y for instance).

Basically, remove the "set t 1 2' commands and see if the result is what
you are looking for.

Jeff Duda

On Sat, Oct 18, 2014 at 2:50 PM, André Petersen <mail at andrepetersen.de>
wrote:

>  Dear subscriber,
>
> 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).
>
> 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?
>
> Best regards,
> André Petersen
>
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>


-- 
Jeff Duda
Graduate research assistant
University of Oklahoma School of Meteorology
Center for Analysis and Prediction of Storms
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