Re: [gembud] Recent model run vs. previous one

Pedro,

I have something similar to what you're asking for set up using gdcntr
to graphically display the difference between a model's initial (i.e.
f000) run and a previous run's forecast verifying at the same time (i.e.
the f012 forecast of the model run 12 hours prior).  For mine, I
basically put the call to gdcntr and set all the variables within a
shell script, and in the gdfile I used the "+" operator to specify that
the data was coming from two separate model runs, for example:

GDFILE   = $direc/na_${newdir}.gem+$GEMDATA/model/gfs_save/${newdir}f000_gfs.gem

This line is taken directly from my script, the $newdir variable is
actually the name of a directory in YYYYMMDDHH format which contains the
data for that specific model run, so as you can see just changing that
variable allows you to compare any model runs you want.

Then for the gdpfun line, I have something like this:

GFUNC    = 
sub[mag[vecr(urel^F${fcast},vrel^F$fcast)],mag[vecr(urel^F000@10+2,vrel^F000@10+2)]]

Which in this case is just subtracting the wind speed from the F0000 run
of the current model from the $fcast run of the older model, so just
change $fcast to whatever forecast time you want that matches the time
of the F000 run.

So I guess in a nutshell what I'm suggesting is to use the "+" operator
in the GDFILE variable to specify two different model runs, and then use
variables within a shell script to denote the various model runs and
forecast times if you want to automatically produce output comparing
several runs or forecast times.

If you'd like a copy of my entire script let me know, I'll be happy to
send it along to you.

Best regards,
Jon Oxtoby


-----Original Message-----
From: gembud-bounces@xxxxxxxxxxxxxxxx
[mailto:gembud-bounces@xxxxxxxxxxxxxxxx] On Behalf Of WAMM
Sent: Monday, September 10, 2007 4:17 PM
To: chiz@xxxxxxxx; gembud@xxxxxxxxxxxxxxxx
Subject: [gembud] Recent model run vs. previous one

All:

I'm trying to write a script that makes a comparison of the most current
model run, say 24h forecast, versus the previous cycle's (say it is 6h
earlier) 30h forecast, effectively valid at the same time.  I'd like to
just be able to see changes in the model solution from previous runs.  I
have something like:

gdpfun=3D sub(hght^1200f012, hght^0600f018)

which actually works, but I'd like to be able to do something like this
with specifying the times, but a more general script in which it
compares the last run versus the previous one, something in the form of:

gdpfun=3D sub(hght^last, hght^'(last-1)')

I'd appreciate any suggestions as soon as possible.

Thanks,
Pedro