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<p class="MsoNormal">Dear Paola, <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Land points in ECCO v4 are defined on a curvilinear grid whose parameters are laid out in the different files of the nctiles_grid/ directory. The grid parameters for your domain are found in nctiles_grid/GRID.0012.nc. Each model grid
cell has a land mask defined at their center XC (longitude), YC (latitude). Each cell has four corners, defined at the points XG, YG.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I plotted the land mask (hFacC) below. Land points are empty white boxes and water points have red dots. The grid cell boundaries are plotting using XG and YG. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">There is a water grid cell that spans approximately 72W to 71W at 30S. The grid cell to the east of that cell spans approximately 71W to 70W and is land. At first glance it would appear that the transport should not change when you move
the eastern endpoint to 70W from 71W. However, you are picking points very close to the grid cell edge. The curvilinear grid is not defined with exactly integer meridians so this might be the source of the problem.
<o:p></o:p></p>
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<p class="MsoNormal">Can you please try to redo the calculation using 69W as the endpoint to see if you get the same value as when 70W is the endpoint? If so, then it would suggest that the first calculation was not counting the grid cell between 72W and 71W
in the transport calculation. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Perhaps Gael might have more to say about this as he wrote the calc_transports routine.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Do let us know what you find. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Ian<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><img width="901" height="611" style="width:9.3854in;height:6.3645in" id="Picture_x0020_1" src="cid:image001.png@01D3ACD9.AFB7B7D0"><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">On 2/22/18, 4:16 PM, "<a href="mailto:ecco-support-bounces@mit.edu">ecco-support-bounces@mit.edu</a> on behalf of Paola Cessi" <<a href="mailto:ecco-support-bounces@mit.edu">ecco-support-bounces@mit.edu</a> on behalf
of <a href="mailto:pcessi@ucsd.edu">pcessi@ucsd.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">I am confused as why the values of transports across a section, as given by calc_transports, change when the endpoints of the section, as given by calc_transports, are changed by one
or two degree on land points. For example, if I change gcmfaces_lines_transp([152 -71],[-30 -30],{'30S Pacific'}); to gcmfaces_lines_transp([152 -70],[-30 -30],{'30S Pacific'}); the transports are different even though
<o:p></o:p></a></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">both 70W 30S and 71W 30S are on land (at least on google maps). Why does this happen? Is there documentation on the actual land point in ECCO, given in lat-lon? <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">Thanks,<o:p></o:p></span></p>
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<span style="mso-bookmark:_MailOriginalBody"><span style="font-size:15.0pt;font-family:Helvetica;color:black"><br>
Paola<o:p></o:p></span></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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