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<font face="Times New Roman">Hello Jamie,<br>
<br>
For the surface layer of the ocean and for variables at the actual
interface between the ocean and the atmosphere, I think it is
clear that sftof, if properly reported, can be used in all cases
to determine which grid cells are ocean (or sea ice), and which
are not. For models reported on their native grids, the values
of sftof will I think either be 0. or 100. (%); for models
regridded to latxlon grids, the values will vary between 0. and
100. This will need to be communicated to users, and I'm open to
suggestions about that.<br>
<br>
For the ocean layers below the surface, there are several options,
but perhaps no general solution. For many fields </font><font
face="Times New Roman">(e.g., theto, so, masscello, etc.)</font><font
face="Times New Roman">, a value of 0. clearly will indicate that
the value is missing (because a reasonably realistic ocean would
never have a value of 0.), or perhaps it will be set to "missing",
so a user could use any of these to infer the mask. I'm not sure
how volcello is being reported when a grid cell is on land or
below the bottom of the ocean. I would think it would also be
either 0.0 or "missing", so it could also be used, but I'm not
sure whether for some ocean grids, cells can appear and disappear
(at the bottom of the ocean). If so, then this field can't be used
in general because it isn't time-dependent. I think we need to
find out from the modeling groups whether volcello would work in
all cases.<br>
<br>
regards<br>
Karl <br>
</font><br>
On 12/6/11 1:23 AM, Kettleborough, Jamie wrote:
<blockquote
cite="mid:E51EDFEBF10BE44BB4BDAF5FC2F024B90FB7F92A@EXXMAIL02.desktop.frd.metoffice.com"
type="cite">
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<div dir="ltr" align="left"><span class="281221709-06122011"><font
color="#0000ff" face="Arial" size="2">Hello Martin, Karl,</font></span></div>
<div dir="ltr" align="left"><span class="281221709-06122011"></span> </div>
<div dir="ltr" align="left"><span class="281221709-06122011"><font
color="#0000ff" face="Arial" size="2">aren't there other
things coming out of this:</font></span></div>
<div dir="ltr" align="left"><span class="281221709-06122011"></span> </div>
<div dir="ltr" align="left"><span class="281221709-06122011"><font
color="#0000ff" face="Arial" size="2">1. who is responsible
for spotting cases where land points are represented by 0.0,
and cases where they are represented by missing value. I
think the implication is at the moment its the users. (I
guess it could have been CMOR - though thats too late now -
it could be something in 'QC' [though I may have used not
quite the right term in saying 'QC']).</font></span></div>
<div dir="ltr" align="left"><span class="281221709-06122011"></span> </div>
<div dir="ltr" align="left"><span class="281221709-06122011"><font
color="#0000ff" face="Arial" size="2">2. how are users to
know the best ways of dealing with the cases? ie to use
sftof? (I guess the danger in giving advice in general on
these sort of things is the advise turns out to be wrong, or
not quite applicable in a particular context).</font></span></div>
<div dir="ltr" align="left"><span class="281221709-06122011"></span> </div>
<div dir="ltr" align="left"><span class="281221709-06122011"><font
color="#0000ff" face="Arial" size="2">Jamie</font></span></div>
<br>
<blockquote style="BORDER-LEFT: #0000ff 2px solid; PADDING-LEFT:
5px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px" dir="ltr">
<div dir="ltr" class="OutlookMessageHeader" align="left"
lang="en-us">
<hr tabindex="-1"> <font face="Tahoma" size="2"><b>From:</b>
<a class="moz-txt-link-abbreviated" href="mailto:go-essp-tech-bounces@ucar.edu">go-essp-tech-bounces@ucar.edu</a>
[<a class="moz-txt-link-freetext" href="mailto:go-essp-tech-bounces@ucar.edu">mailto:go-essp-tech-bounces@ucar.edu</a>] <b>On Behalf Of </b>Karl
Taylor<br>
<b>Sent:</b> 05 December 2011 18:59<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:martin.juckes@stfc.ac.uk">martin.juckes@stfc.ac.uk</a><br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:cmip5-users@jiscmail.ac.uk">cmip5-users@jiscmail.ac.uk</a>;
<a class="moz-txt-link-abbreviated" href="mailto:go-essp-tech@ucar.edu">go-essp-tech@ucar.edu</a>; <a class="moz-txt-link-abbreviated" href="mailto:graham.parton@stfc.ac.uk">graham.parton@stfc.ac.uk</a><br>
<b>Subject:</b> Re: [Go-essp-tech] Incorrect use of missing
value in some MRI ocean data -- correction<br>
</font><br>
</div>
<font face="Times New Roman">Hi Martin,<br>
<br>
Right again.<br>
<br>
thanks,<br>
Karl<br>
</font><br>
On 12/5/11 10:39 AM, <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:martin.juckes@stfc.ac.uk">martin.juckes@stfc.ac.uk</a>
wrote:
<blockquote
cite="mid:E21FBC3F00D7304687CB46529F9676D71C837DE3@EXCHMBX01.fed.cclrc.ac.uk"
type="cite">
<pre wrap="">Hello Karl,
Seiji (from MRI) suggested people use sea-area fraction"sftof": I think "areacello" (standard name "cell_area") refers to the actual grid cell, which may be be partially or completely land. "volcello" (standard name "ocean_volume") doesn't have a definition in the current standard name table -- but from the name I would expect to refer to the volume of ocean, so that should be OK for the height dependent fields,
cheers,
Martin
________________________________
From: Karl Taylor [<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:taylor13@llnl.gov">taylor13@llnl.gov</a>]
Sent: 05 December 2011 18:21
To: Juckes, Martin (STFC,RAL,RALSP)
Cc: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:go-essp-tech@ucar.edu">go-essp-tech@ucar.edu</a>; Parton, Graham (STFC,RAL,RALSP); <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:cmip5-users@jiscmail.ac.uk">cmip5-users@jiscmail.ac.uk</a>
Subject: Re: [Go-essp-tech] Incorrect use of missing value in some MRI ocean data -- correction
Hi Martin,
You're quite right. It states:
"2. Unless otherwise specified, the ocean and sea-ice output (including Oclim, Oyr, Omon, and OImon) represents a mean over only the sea portion of each grid cell (i.e., it is interpreted as "where ocean over ocean"), and a value of 0.0 should be reported where the sea fraction is 0."
I'm can't recall whether this specification was the result of some requirement, or if it was simply a mistake. Thinking about it now, I think the recommendation should have been to set it to the "missing" value, not 0.0, since over land the values are undefined.
Given that some groups will follow the specified rule, and others will put in the missing value for land points, users would be advised to obtain the areacello variable (or volcello) which should be set to 0.0 where there is no ocean.
Any other ideas?
Best regards,
Karl
On 12/5/11 9:45 AM, <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:martin.juckes@stfc.ac.uk">martin.juckes@stfc.ac.uk</a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:martin.juckes@stfc.ac.uk"><mailto:martin.juckes@stfc.ac.uk></a> wrote:
Hello Karl,
In the following:
<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://cmip-pcmdi.llnl.gov/cmip5/docs/standard_output.xls">http://cmip-pcmdi.llnl.gov/cmip5/docs/standard_output.xls</a>, sheet "general", column A, row 15 and 17.
It says "the value 0.0 should be reported where the sea fraction is 0",
regards,
Martin
________________________________
From: Karl Taylor [<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:taylor13@llnl.gov">taylor13@llnl.gov</a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:taylor13@llnl.gov"><mailto:taylor13@llnl.gov></a>]
Sent: 05 December 2011 16:42
To: Juckes, Martin (STFC,RAL,RALSP)
Cc: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:go-essp-tech@ucar.edu">go-essp-tech@ucar.edu</a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:go-essp-tech@ucar.edu"><mailto:go-essp-tech@ucar.edu></a>; Parton, Graham (STFC,RAL,RALSP); <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:cmip5-users@jiscmail.ac.uk">cmip5-users@jiscmail.ac.uk</a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:cmip5-users@jiscmail.ac.uk"><mailto:cmip5-users@jiscmail.ac.uk></a>
Subject: Re: [Go-essp-tech] Incorrect use of missing value in some MRI ocean data -- correction
Dear Martin and all,
For 3-d ocean fields like thetao, I think the missing value (not 0.0) should invariably be assigned to all land grid cells and for grid cells below the bottom of the ocean. I can't find where in the document pointed to below it says otherwise. I would like to correct the document, so please tell me where it needs revision.
thanks,
Karl
On 12/4/11 8:07 PM, <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:martin.juckes@stfc.ac.uk">martin.juckes@stfc.ac.uk</a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:martin.juckes@stfc.ac.uk"><mailto:martin.juckes@stfc.ac.uk></a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:martin.juckes@stfc.ac.uk"><mailto:martin.juckes@stfc.ac.uk></a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:martin.juckes@stfc.ac.uk"><mailto:martin.juckes@stfc.ac.uk></a> wrote:
I owe MRI an apology -- the use of zero instead of a missing value is in fact recommended in (<a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://cmip-pcmdi.llnl.gov/cmip5/docs/standard_output.xls">http://cmip-pcmdi.llnl.gov/cmip5/docs/standard_output.xls</a>),
regards,
Martin
________________________________________
From: Juckes, Martin (STFC,RAL,RALSP)
Sent: 04 December 2011 08:45
To: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:go-essp-tech@ucar.edu">go-essp-tech@ucar.edu</a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:go-essp-tech@ucar.edu"><mailto:go-essp-tech@ucar.edu></a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:go-essp-tech@ucar.edu"><mailto:go-essp-tech@ucar.edu></a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:go-essp-tech@ucar.edu"><mailto:go-essp-tech@ucar.edu></a>; Parton, Graham (STFC,RAL,SSTD); <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:cmip5-users@jiscmail.ac.uk">cmip5-users@jiscmail.ac.uk</a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:cmip5-users@jiscmail.ac.uk"><mailto:cmip5-users@jiscmail.ac.uk></a><a moz-do-not-send="true" class="moz-txt-link-rfc2396E" href="mailto:cmip5-users@jiscmail.ac.uk"><mailto:cmip5-users@jiscmail.ac.uk></a><a moz-do-not-send="tr
ue" class="moz-txt-link-rfc2396E" href="mailto:cmip5-users@jiscmail.ac.uk"><mailto:cmip5-users@jiscmail.ac.uk></a>
Cc: Pascoe, Stephen (STFC,RAL,RALSP)
Subject: Incorrect use of missing value in some MRI ocean data.
Hello,
It has come to light that some MRI ocean data has land grid points set to zero rather than to the declared missing value. This is likely to confuse some applications reading and plotting the data -- I've notified Seiji Yukimoto at MRI,
sincerely,
Martin
</pre>
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