NetCDF issue?

[Matt Alonso]

Hi Jennifer,


Did you build GrADS from source on this machine?
>

Yes

>
> Looks like you have converted grib2 into netcdf -- one file per forecast
> time. Is that right?
>

Yes, I created one netcdf file per grib2 forecast run (ie 01.nc would
contain all 61 time periods from the 12z WW3 run); see more thorough
description below.


>
> There are some bugs in the gancgrid() routine in 2.0.a1 that I believe
> have been fixed for the next release. The gancgrid() routine is designed for
> speeding up the I/O from OPeNDAP servers, but it can work for non-pdef
> non-templated local netcdf files too. The non-templated condition for
> calling gancgrid() is what's missing in 2.0.a1 plus some other bug fixes
> in the subroutine itself.
>
> You can bypass the gancgrid() routine by changing one line of code in
> gaio.c (lines 212-216) and re-compiling:
>
>   /*   if (!strncmp(pgrid->pfile->name,"http://",7)) { */
>   if ((!strncmp(pgrid->pfile->name,"http://",7)) || ((pfi->ncflg==1) &&
> (pfi->ppflag==0))) {
>     rc = gancgrid(gr,gru,id,jd,d,dx);
>     return (rc);
>   }
>
> If you un-comment out the first line and comment out the second -- i.e.,
> call gancgrid only for opendap data sets -- then the I/O should work.
>
> However, it sounds like you are also making a mistake in the way you are
> templating your netcdf files. If you have one file per forecast time, you
> can aggregate them into one data set (with XDFOPEN and OPTIONS TEMPLATE) so
> there's no need to have each time step be in a separate data set. Also, when
> you call the smth9() function, which dimensions are varying?
>

I will modify the src accordingly and see if that helps.

I think I may have misspoke initially when describing the setup of the
various files or perhaps I am just misunderstanding.  As I attempted to
clarify above each netcdf file has the exact same contents as the original
grib2 file on NCEP's FTP site (
ftp://ftpprd.ncep.noaa.gov/pub/data/nccf/com/wave/prod/wave.20080317).

I want to show how the model is trending by using an "ensemble" of the
previous 7 runs.  When my script is executed it inserts the newest runs data
into 00.nc and "bumps" the previous runs down.  If the newest run is the 12Z
run for today (20080317) the netcdf files would contain the data for the
various runs as follows:

00.nc -> 12Z 20080317
01.nc -> 06Z 20080317
02.nc -> 00Z 20080317
03.nc -> 18Z 20080316
...

And so on until there are 8 netcdf files.  Would your templating example
still apply and help me display data in the manner I describe above?  I
attached a sample image which is being generated by this same script but is
running in GrADS 1.8S11.

Thanks as always.

Cheers,
Matt
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