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<span style="font-size: 12pt;">Hi,</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">We run a THREDDS server,<a href="http://thredds.atmos.albany.edu:8080/thredds/catalog.html" target="_blank" rel="noopener noreferrer" data-auth="NotApplicable" id="LPlnk19948" class="OWAAutoLink" previewremoved="true">http://thredds.atmos.albany.edu:8080/thredds/catalog.html</a> (running
TDS version 4.6.10) that serves out a variety of datasets. One of the datasets consists of 4x/day yearly gridded data in NetCDF format.</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">NCL 6.5.0 (and earlier versions), when reading in data via OpenDAP, while not throwing an error, will typically produce output where a requested variable has values of 0 for all points. This looks to be related to the size of
the dataset. The attached script attempts to read from files containing SLP data from Jan. 1 2018 to either present, 125 days in, or 25 days in. Only the shortest time window produces expected output.</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">If I use the direct filepath (i.e. no OpenDAP) to where the data file actually sits on our filesystem, the expected values appear for all three time-extents.</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">This behavior occurs both on my THREDDS instance and another OpenDAP service (both point to the same physical files) when using NCL. However, reading the data using Python’s opendap-capable libraries (e.g. xarray) works fine.</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">The attached script should work from any NCL client with OpenDAP built in. I’ve also attached the output from running the script locally; one sees correct values of SLP min/max on the first URL, but zeroes for the next two.</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">Thanks for any insight!</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">Cheers,</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<span style="font-size: 12pt;">Kevin</span></p>
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<span style="font-size: 12pt;"> </span></p>
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<div class="PlainText">_____________________________________________<br>
Kevin Tyle, M.S.; Manager of Departmental Computing<br>
Dept. of Atmospheric & Environmental Sciences <br>
University at Albany<br>
Earth Science 235, 1400 Washington Avenue <br>
Albany, NY 12222<br>
Email: ktyle@albany.edu<br>
Phone: 518-442-4578 <br>
_____________________________________________<br>
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