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<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial>Hello Karl,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial>I think the recommended way to 'turn off' ext_cell_measures is
to make a call to cmor.set_variable_attribute(varid, 'ext_cell_measures',
''). Is that right? We are very tempted to do this for all variables
- so basically overriding the MIP tables. How big a problem do you think
this will be for data users - our grid is pretty straight forward and users can
calculate cell_areas from the latitudes.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial>That aside, doesn't the approach of providing alternative
grid areas need more discussion?</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial> 1. how should we produce these. The most natural
approach I can think of is to modify the fx MIP tables to add in areacellb (or
whatever we choose to call it) and then output through CMOR - this will maximise
the chance of consistency between different grid area files for any one
model. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=994545009-29102010><FONT color=#0000ff
size=2 face=Arial> 2. how should we reference these additional
areas from a variable.? I could call cmor.set_variable_attribute(varid,
'ext_cell_measures', 'areacellb') - but in the tests I've done on CMOR 2.4 this
only does half the job: it puts the appropriate ext_call_measures attribute into
the file, but does nothing with associatedFiles.</FONT></SPAN></DIV>
<DIV><SPAN class=994545009-29102010><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=994545009-29102010><FONT color=#0000ff size=2
face=Arial>Clearly these may have been things you were going to cover - but ran
out of time to, in which case sorry.</FONT></SPAN></DIV>
<DIV><SPAN class=994545009-29102010><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=994545009-29102010><FONT color=#0000ff size=2 face=Arial>I
think another scenario that still needs some thought is one where a data
provider has submitted data and published it in ESG. They then realise
they made a mistake - they should have turned ext_cell_measures off, but didn't
(or visa-versa). What happens in this case? (We have kind of done this in
that we have send data with incorrect cell_measures to the BADC - but
have caught the issue before ingestion into ESG - I don't believe we will
always be this lucky). You'll probably see through why I'm
asking this question about meta-data updates again now, so I may as well be
explicit... If we choose to turn off ext_cell_measures for all our diagnostics
on this initial submission - what are our options for recovering from this
if we later found the decision to submit without ext_cell_measures was
making our data hard to use?</FONT></SPAN></DIV>
<DIV><SPAN class=994545009-29102010><FONT color=#0000ff size=2
face=Arial></FONT></SPAN> </DIV>
<DIV><SPAN class=994545009-29102010></SPAN><FONT face=Arial><FONT
color=#0000ff><FONT size=2>J<SPAN
class=994545009-29102010>amie</SPAN></FONT></FONT></FONT><BR></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #0000ff 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"
dir=ltr>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> Karl Taylor [mailto:taylor13@llnl.gov]
<BR><B>Sent:</B> 29 October 2010 02:15<BR><B>To:</B> Bentley,
Philip<BR><B>Cc:</B> V. Balaji; martin.juckes@stfc.ac.uk;
go-essp-tech@ucar.edu; cmor@lists.llnl.gov; Kyle.Olivo@noaa.gov; Doutriaux,
Charles; Kettleborough, Jamie<BR><B>Subject:</B> Re: [Go-essp-tech] CMOR and
cell_measures issues<BR></FONT><BR></DIV>
<DIV></DIV><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="">
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