<div dir="ltr"><div>Hi</div><div><br></div><div>This is the thread mentioned by Dave Allured:</div><div><a href="https://mailman.ucar.edu/pipermail/ncl-talk/2021-February/017831.html" target="_blank">https://mailman.ucar.edu/pipermail/ncl-talk/2021-February/017831.html</a></div><div><br></div><div>You probably have variables lat(x_t,y_t), and lon(x_t,y_t). <br></div><div>Hopefully also the inverse functions x_t(lat,lon) and y_t(lat,lon),</div><div>which would allow you to plot the parallels and meridians overlaid to the map. <br></div><div>These variables may be in this data file or</div><div>in a separate file with grid information.</div><div><br></div><div>Ideally one of these files also has information on the map projection used to generate x_t and y_t.</div><div>It looks like a Transverse Mercator projection, centered in a meridian along the middle of</div><div>the Atlantic ocean (30W or 35W), but it may be a different specialized projection.</div><div><a href="https://en.wikipedia.org/wiki/Transverse_Mercator_projection">https://en.wikipedia.org/wiki/Transverse_Mercator_projection</a></div><div><br></div><div>I would guess this projection (the one you used in your plot) <br></div><div>is probably the one in which the whole map looks nicer,</div><div>especially if you overlay the parallels and meridians as suggested above,</div><div>because this will show geographic location more clearly.<br></div><div><br></div><div>Since this data includes the North Pole, which is a singularity in the standard cylindrical Mercator projection,</div><div>you won't be able to plot the Arctic using standard Mercator projection,</div><div>everything will be more and more distorted near the North pole.<br></div><div><a href="https://en.wikipedia.org/wiki/Mercator_projection">https://en.wikipedia.org/wiki/Mercator_projection</a></div><div><br></div><div>You could use the stereographic projection centered on the North Pole (is that what you mean by "polar map"?),</div><div>with meridians appearing as radial straight lines, and parallels as concentric circles,<br></div><div>but that will also make the equatorial region and the Southern Hemisphere appear distorted,</div><div>although it may be OK if you want to plot only the Arctic region.<br></div><div><a href="https://en.wikipedia.org/wiki/Stereographic_projection_in_cartography">https://en.wikipedia.org/wiki/Stereographic_projection_in_cartography</a></div><div><br></div><div>I hope this helps,<br></div><div>Gus Correa<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Mar 13, 2021 at 10:46 AM Dave Allured - NOAA Affiliate via ncl-talk <<a href="mailto:ncl-talk@mailman.ucar.edu" target="_blank">ncl-talk@mailman.ucar.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Check your original source data file for an extra set of coordinates, lat and lon, or similar names. x_t and y_t are not lat and lon, they are projection coordinates, probably in meters. If lat and lon are not in the original file, you might also be able to request them from the data source.<div><br></div><div>See recent thread about OSGB grid for method of using the supplemental coordinates.<div><br><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Mar 13, 2021 at 1:38 AM Chathurika via ncl-talk <<a href="mailto:ncl-talk@mailman.ucar.edu" target="_blank">ncl-talk@mailman.ucar.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><p style="font-family:Arial">
<span style="font-size:16px;font-family:Georgia">Hello,</span>
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<span style="font-size:16px;font-family:Georgia">Thank you very much for reading my email. </span>
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<span style="font-size:16px;font-family:Georgia"><br>
</span>
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<span style="font-size:16px;font-family:Georgia">I have downscaling data in Atlantic and Arctic Oceans. But It has no attached coordinates. I want to plot these data on a polar map with coordinates. </span>
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<span style="font-size:16px;font-family:Georgia">This is the variable summary;</span>
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</p><p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>Copyright (C) 1995-2018 - All Rights Reserved</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>University Corporation for Atmospheric Research</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>NCAR Command Language Version 6.5.0</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>The use of this software is governed by a License Agreement.</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>See <a href="http://www.ncl.ucar.edu/" target="_blank">http://www.ncl.ucar.edu/</a> for more details.</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;min-height:13px;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"></span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Variable: zos1</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Type: float</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Total Size: 2548039680 bytes</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>637009920 values</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Number of Dimensions: 3</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Dimensions and sizes: [Time | 240] x [y_t | 1728] x [x_t | 1536]</span>
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<span style="font-variant-ligatures:no-common-ligatures">Coordinates:<span> </span></span>
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<span style="font-variant-ligatures:no-common-ligatures"><span> </span>Time: [7.260877e+09..7.8894e+09]</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>y_t: [0.5..1727.5]</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>x_t: [0.5..1535.5]</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Number Of Attributes: 5</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>grid : TS</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>missing_value : -1e+34</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>units : m</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>long_name : Sea Surface Height</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>_FillValue : -1e+34</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;min-height:13px;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"></span>
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</p><p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Variable: xt</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Type: float</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Total Size: 6144 bytes</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>1536 values</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Number of Dimensions: 1</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Dimensions and sizes: [x_t | 1536]</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Coordinates:<span> </span></span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>x_t: [0.5..1535.5]</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures">Number Of Attributes: 2</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>long_name : X on T grid</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-variant-ligatures:no-common-ligatures"><span> </span>units :</span>
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<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<br>
</p>
<span style="font-size:16px;font-family:Georgia">If I plot the data as a contour plot using "</span><span style="font-family:Georgia;font-size:16px">gsn_csm_contour" the figure looks like the attached png. Please help me to solve this. </span>
<p></p>
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<span style="font-family:Arial"><br>
</span>
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<span style="font-family:Georgia;font-size:16px">Thank you very much and best regards,</span>
</p>
<p style="margin-bottom:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;white-space:normal">
<span style="font-family:Georgia;font-size:16px">Chathu</span></p>
<p></p>
[image]<span style="font-family:Arial"><blockquote style="margin:0px 0px 0px 40px;padding:0px;font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:small;font-variant-ligatures:normal;border:medium none">
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<blockquote style="margin:0px 0px 0px 40px;padding:0px;font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-variant-ligatures:normal;border:medium none">
<span style="font-style:italic"><span style="font-size:x-small">Wickramage Chathurika Hemamali</span></span>
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<span style="font-style:italic"><span style="font-size:x-small">Msc in Physical Oceanography</span></span>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2251">
<span style="font-style:italic"><span style="font-size:x-small">State Key Laboratory of Tropical Oceanography</span></span>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2252">
<span style="font-style:italic"><span style="font-size:x-small">South China Sea Institute of Oceanology</span></span>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2252">
<span style="font-style:italic"><span style="font-size:x-small">University of Chinese Academy of Science</span></span>
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</div>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264">
<span style="font-style:italic"><span style="font-size:x-small">China</span></span>
</div>
</div>
<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<span style="font-style:italic;font-size:medium"><br>
</span>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<i><span style="font-size:xx-small">Specialized in Oceanography and Marine Geology (Bachelor)</span></i>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<i><span style="font-size:xx-small">University of Ruhuna</span></i>
</div>
<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<i><span style="font-size:xx-small">Matara</span></i>
</div>
<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<i><span style="font-size:xx-small">Sri Lanka</span></i>
</div>
<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<span style="font-style:italic;font-size:medium"><br>
</span>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<span style="font-style:italic;font-size:medium">Email : <a>wickramagechathurika@rocketmail.com</a></span>
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<div id="gmail-m_5932723212260111670gmail-m_3239497033442535611gmail-m_3850454551382989427m_-3860502895539816637ydpc6aa4ef1yui_3_16_0_ym19_1_1496286059659_2264" style="font-size:small">
<span style="font-style:italic;font-size:medium"><a>chatu@scsio.ac.cn</a></span></div></blockquote></span></blockquote></div></div></div></div>
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