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<font face="Times New Roman">Dear all,<br>
<br>
I meant to try to address all the stuff in this discussion, but
won't have time today. This email is just to say that I think we
should insist that the cell_area files (areacella and areacello)
be placed in the archive, even if there are also gridspec files.
The ext_cell_measures attribute should also be included for fields
that are on the "standard" grid (i.e., the one with the cell areas
stored in areacella or areacello). If there are other fields for
which the standard areas are inappropriate and where your
scientists think it is important to provide cell areas, then I
recommend that you create specially named variables and place them
in the "fx" subdirectories. For variables not on the "standard"
grid (i.e., the grid of areacella or areacello), you should "turn
off" the ext_cell_measures attribute.<br>
<br>
I don't expect most groups to produce gridspec files, so most
analysts will be looking for areas in the areacella and areacello
variables, not the gridspec files. This is why you should write
the areacella and areacello files even if you also write the
gridspec files.<br>
<br>
Also, could you please explain why you prefer not to duplicate the
"fx" fields in each experiment's directory tree. <br>
<br>
Best regards,<br>
Karl<br>
</font><br>
On 10/25/10 7:12 AM, Bentley, Philip wrote:
<blockquote
cite="mid:E51EDFEBF10BE44BB4BDAF5FC2F024B9036364A5@EXXMAIL02.desktop.frd.metoffice.com"
type="cite">
<pre wrap="">Hi Balaji,
</pre>
<blockquote type="cite">
<pre wrap="">Phil, I'm very impressed that Had will have gridspec files,
is this a done deal? I've been so pessimistic about this that
I was wondering if even we should do one ourselves.
</pre>
</blockquote>
<pre wrap="">
Nope, not a done deal yet :-(
In line with the CMIP5 expt design doc, we don't really need to provide
gridspec files since all our model output is on either regular or
uniform grids (i.e. simple cartesian product of lat & long).
However, this whole cell_measures business prompted me to revisit the
gridspec tools and output, which reminded me that the gridspec netcdf
files include a cell area variable. Which in turn means we wouldn't need
to provide a separate file (or files) for cell areas. Hence we could
drop the ext_cell_measures attribute from our CMIP5 output files.
Using the gridspec tools may be a quick and easy way for us to provide
cell area info if we need to.
Caveat: from a quick glance it looks like the netcdf files produced by
the gridspec tools are not CF compliant. Is this is an issue? Presumably
it is if we want all the data in the CMIP5 archive to be CF compliant.
(NB: it could be I'm not running with the very latest version of the
tools - but I couldn't see a more recent version on the gfdl web site).
</pre>
<blockquote type="cite">
<pre wrap="">You know of course that gridspec says you can supply
</pre>
<blockquote type="cite">
<pre wrap="">gridspec_fx_HadGEM2-ES_atm_pgrid.nc
gridspec_fx_HadGEM2-ES_atm_ugrid.nc
gridspec_fx_HadGEM2-ES_atm_vgrid.nc
gridspec_fx_HadGEM2-ES_atm_uvgrid.nc
</pre>
</blockquote>
<pre wrap="">
as one single supergrid...
</pre>
</blockquote>
<pre wrap="">
If I could figure out how to output all 7 or 8 atm/ocn (sub-)grids to a
single netcdf file I would, but the available documentation (e.g. for
make_hgrid) isn't clear on this point. Sorry, that's probably just me
being dumb! But if there is updated documentation then please point me
to it. If necessary I could concatenate variables afterwards using NCO
tools.
Right now I'm trying to figure out how to create a gridspec file for our
HadGEM2 ocean model, which uses a stretched (i.e. tartan/plaid) grid:
longitudes are evenly spaced, latitudes vary from 1 deg to 1/3 deg.
(Looks like I need to use the --my_grid_file option to supply the
lat/long coords).
</pre>
<blockquote type="cite">
<pre wrap="">
But if you're doing gridspec at all, I will concede this
point:-). Let's both do these separate gridspecs for now.
</pre>
</blockquote>
<pre wrap="">
Works for me.
I think we're suffering from 'early-adopter syndrome' :-/
Cheers,
Phil
</pre>
<blockquote type="cite">
<pre wrap="">
Bentley, Philip writes:
</pre>
<blockquote type="cite">
<pre wrap="">Hi Karl,
A somewhat belated follow-up question in connection with
</pre>
</blockquote>
<pre wrap="">this proposal
</pre>
<blockquote type="cite">
<pre wrap="">(and with some slight overlap with Jamie's email which
</pre>
</blockquote>
<pre wrap="">crossed on the
</pre>
<blockquote type="cite">
<pre wrap="">ether)...
As things stand the files named in the 'associated_files' attribute
appear thus (using our RCP 4.5 simulation as an example):
"... gridspecFile: gridspec_fx_HadGEM2-ES_rcp45_r0i0p0.nc areacella:
areacella_fx_HadGEM2-ES_rcp45_r0i0p0.nc"
Are the <expt_id>_<rip> parts (i.e. 'rcp45_r0i0p0.nc' ) actually
required? AFAIK, our gridspec/cellarea files will not
</pre>
</blockquote>
<pre wrap="">change from one
</pre>
<blockquote type="cite">
<pre wrap="">simulation to the next using the same model (HadGEM2-ES in
</pre>
</blockquote>
<pre wrap="">this case).
</pre>
<blockquote type="cite">
<pre wrap="">
Since, like most centers, we will be running large numbers of
simulations using the same model, it looks like we would need to
create numerous duplicates of the gridspec/cellarea files -
</pre>
</blockquote>
<pre wrap="">or lots of
</pre>
<blockquote type="cite">
<pre wrap="">symlinks
- in order to for these references to make sense. Unless you are
planning to manage that on our behalf somehow...?
I think our 4 gridspec files for the HadGEM2 atm grids are
</pre>
</blockquote>
<pre wrap="">likely to
</pre>
<blockquote type="cite">
<pre wrap="">be called something like...
gridspec_fx_HadGEM2-ES_atm_pgrid.nc
gridspec_fx_HadGEM2-ES_atm_ugrid.nc
gridspec_fx_HadGEM2-ES_atm_vgrid.nc
gridspec_fx_HadGEM2-ES_atm_uvgrid.nc
So without any simulation-specific info. (There would also be files
for the ocean grids)
As it happens the gridspec files contain grid cell areas,
</pre>
</blockquote>
<pre wrap="">so I'm now
</pre>
<blockquote type="cite">
<pre wrap="">wondering if we'd even supply both?
I'd be interested to hear your thoughts on this. I may be
mis-understanding something/everything :-)
Regards
Phil
</pre>
</blockquote>
</blockquote>
<pre wrap="">
</pre>
</blockquote>
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