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<p class="MsoNormal"><span style="font-size:12.0pt">Jean-Michel,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">I think that changing some variable descriptions would be enough to overcome most of the confusion.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">It was pointed out to me that the velocities in UVELMASS/VVELMASS are “</span><span style="font-size:12.0pt;color:black">essentially are mass weighted given that we are using the boussinesq approximation</span><span style="font-size:12.0pt">”.
I can’t argue with that....<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Someone (probably Gael) used different descriptions for some of the variables in the ECCO Central Production README file(ftp://ecco.jpl.nasa.gov/Version4/Release3/nctiles_monthly/README).
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Here is a somewhat edited snippet of some very well described fields:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Vm_dPHdy V momentum tendency from Hydrostatic Pressure grad (m/s^2) along the model’s y-direction but may not be east.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">VVEL V component of velocity (m/s) along the model's y-direction but may not be north. NVEL is the north velocity.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">VVELMASS V geometry-weighted component of velocity (m/s) along the model's y-direction but may not be north. VVELMASS is VVEL times hFacS to account for
<o:p></o:p></span></p>
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<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Other fields are given a more succinct but still accurate description.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> SIuice SEAICE x-dir. ice velocity (m/s)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> SIvice SEAICE y-dir. ice velocity (m/s)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">And still others mention “west” and “south” faces, faces that we all know refer to the “left” and “bottom” faces of the Arakawa-C tracer cell but that may not be obvious to a new user:
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> ADVxHEFF U Comp. Advective Flux of eff ice thickness (m.m^2/s) at the western face. Positive to increase eff ice thickness.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"> ADVx_SLT U Comp. Advective Flux of Salinity (psu.m^3/s) at the western face. Positive to increase salt.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">If space in the description field is not an issue, then my vote is for being as descriptive as possible (i.e., following the example of the first snippet). If space is an issue then if something like
</span><span style="font-size:12.0pt;color:black">the examples below would fit then it would be enough,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">VVELMASS V geometry-weighted velocity (m/s) in y-dir. VVELMASS = VVEL x hFacS to account for varying cell height (hFacS between 0 and 1).</span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">As for the ‘west’ and ‘south’ faces mentioned in the description, perhaps references to the C-grid would suffice, such as
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">ADVxHEFF U-component advective flux of average ice thickness (m.m^2/s) through the western face of the C-grid tracer cell.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">ADVyHEFF V-component advective flux of average ice thickness (m.m^2/s) through the southern face of the C-grid tracer cell.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">But there may be even clearer methods.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">What do you think?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Ian<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">On 1/16/18, 3:42 PM, "MITgcm-devel on behalf of Jean-Michel Campin" <<a href="mailto:mitgcm-devel-bounces@mitgcm.org">mitgcm-devel-bounces@mitgcm.org</a> on behalf of
<a href="mailto:jmc@mit.edu">jmc@mit.edu</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><a name="_MailOriginalBody">Hi Ian,<o:p></o:p></a></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Any update that can improve/avoid confusion is welcome !<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Changing some diagnostic descriptions is easy, we just need to agree on what<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">to put instead (and may be some consistency across diagnostic descriptions).<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">If you want also to change diagnostic names (e.g., "UVELMASS" --> ? ), it's
<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">a little bit more tricky since many users are now used to specify these (bad)<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">8-characters diagnostic names in their data.diagnostics, so the transition<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">might be a little painful.<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">And just to bring an historical perspective, "UVELMASS", "VVELMASS" names<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">and description were added early on (Mars 11, 2004); from an atmospheric<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">point of view, using pressure coordinate, the "mass weighted" makes more
<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">sense (hFac capture the time-dependence of the grid-box mass content).<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Cheers,<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Jean-Michel<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">On Tue, Jan 16, 2018 at 07:02:30PM +0000, Fenty, Ian G (329C) wrote:<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Hi MITgcm devel,<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">In an effort to make our output more comprehensible to outsiders I think we should consider updating the names of some of our diagnostic output descriptions.<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">First, terms such as UVELMASS and UTHMASS are not ???Zonal components of velocity???, they are the component of velocity in the model grid???s ???x??? direction. In
the LLC tiles, 6 of the 13 tiles (or 2 of 5 faces) are rotated by 90 degrees so that flow in the ???+x??? direction is actually negative quasi-meridional. Moreover, with the Arctic Cap tile 7 (face 3) flow in the positive ???x??? direction is eastward along
its bottom edge (first row) and westward along its upper edge (last row). A similar story applies for flow in the +y direction. So, can we change these names to reflect the fact that ???u??? and ???v??? are defined not by the compass but by the local orientation
of the curvilinear grid?<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Second, the name ???MASS??? and the description ???Mass-Weighted??? is also somewhat misleading because these terms are not weighted by mass at all, but by hFac. Perhaps
a more descriptive term would be ???Geometry-Weighted??? or some other name that reflects the possible non-unity value of hFac?<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">This topic has come up many times since we???ve adopted the LLC grids for the ECCO Central Production and other projects. I???d like to see this sorted out to reduce
the confusion that seems to hit everybody encountering these variables for the first time.<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"> * Ian<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">45 |UVELMASS| 50 | 46 |UUr MR|m/s |Zonal Mass-Weighted Comp of Velocity (m/s)<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">46 |VVELMASS| 50 | 45 |VVr MR|m/s |Meridional Mass-Weighted Comp of Velocity (m/s)<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">50 |UTHMASS | 50 | 51 |UUr MR|degC.m/s |Zonal Mass-Weight Transp of Pot Temp<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">51 |VTHMASS | 50 | 50 |VVr MR|degC.m/s |Meridional Mass-Weight Transp of Pot Temp<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">_______________________________________________<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">MITgcm-devel mailing list<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"></span><a href="mailto:MITgcm-devel@mitgcm.org"><span style="mso-bookmark:_MailOriginalBody">MITgcm-devel@mitgcm.org</span><span style="mso-bookmark:_MailOriginalBody"></span></a><span style="mso-bookmark:_MailOriginalBody"><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">_______________________________________________<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"></span><a href="mailto:MITgcm-devel@mitgcm.org"><span style="mso-bookmark:_MailOriginalBody">MITgcm-devel@mitgcm.org</span><span style="mso-bookmark:_MailOriginalBody"></span></a><span style="mso-bookmark:_MailOriginalBody"><o:p></o:p></span></p>
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