<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>Hi Ken, all, I am leaving for Florida& Cuba tomorrow. Likely, I won't be able to get back to you till I return. Cheers, D<br><br>Sent from my iPhone</div><div><br>On Jan 10, 2018, at 2:01 PM, Ken Knapp - NOAA Federal <<a href="mailto:ken.knapp@noaa.gov">ken.knapp@noaa.gov</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Hi Dennis<div><br></div><div>Thanks for the info. The form that best fits my needs is H.4.1</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><b>H.4.1. Multidimensional array representation of trajectories</b></blockquote><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">When storing multiple trajectories in the same file, and the number of elements in each trajectory is the same, one can use the multidimensional array representation. <u>This representation also allows one to have a variable number of elements in different trajectories, at the cost of some wasted space. In that case, any unused elements of the data and auxiliary coordinate variables must contain missing data values (section 9.6).</u> </blockquote></blockquote><div><br></div><div>I've underlined the part that I thought gave me this option: some tracks are long and some aren't. However, keeping the variable that holds the tracks all the same size makes file manipulation easy.</div><div><br></div><div>The underlined portion above seems to suggest that this should be possible. But it would imply that there is no track data for some parts of the variable, which would imply that the coordinate variable would have missing data. But that seems at odds with other portions of the documentation. (where it says coordinate variable data should not be missing).</div><div><br></div><div>Thoughts?</div><div>-Ken</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Jan 8, 2018 at 4:54 PM, Dennis Shea <span dir="ltr"><<a href="mailto:shea@ucar.edu" target="_blank">shea@ucar.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Carl, Ken<br><br>It was suggested to me that the following may be helpful to you:<br><br>==<br>The 'suggestor' wrote he would use either H.4.3 or H.4.4 <div><a href="http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/cf-conventions.html#trajectory-data" target="_blank">http://cfconventions.org/Data/<wbr>cf-conventions/cf-conventions-<wbr>1.7/cf-conventions.html#trajec<wbr>tory-data</a><br><br></div><div>Let ncl-talk know what 'trajectory' [ I'm so clever :-) !!! ] you decide to pursue.<br><br></div><div>Regards<span class="HOEnZb"><font color="#888888"><br></font></span></div><span class="HOEnZb"><font color="#888888"><div>D<br></div><div class="m_-4174262033547365150gmail-yj6qo m_-4174262033547365150gmail-ajU"><div id="m_-4174262033547365150gmail-:39c" class="m_-4174262033547365150gmail-ajR"><br></div></div></font></span></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Jan 5, 2018 at 10:47 AM, Dennis Shea <span dir="ltr"><<a href="mailto:shea@ucar.edu" target="_blank">shea@ucar.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div>Hi Carl, Ken<br><br><br>The following can be used to check for CF conformance:<br><br> <a href="http://puma.nerc.ac.uk/cgi-bin/cf-checker.pl" target="_blank">http://puma.nerc.ac.uk/cgi-bin<wbr>/cf-checker.pl</a><br><br>==============================<wbr>============<br><br></div>As you likely know, there are:<br> (i) "coordinate variable(s)" <br>and <br> (ii) variable(s) that contain coordinates. <br><br>:-)<br>====<br>Unidata: <br> <a href="https://www.unidata.ucar.edu/software/netcdf/docs/netcdf_data_set_components.html" target="_blank">https://www.unidata.ucar.edu/s<wbr>oftware/netcdf/docs/netcdf_dat<wbr>a_set_components.html</a><br><br></div>Coordinate Variables (CVs):<br> <a href="https://www.unidata.ucar.edu/software/netcdf/docs/netcdf_data_set_components.html#coordinate_variables" target="_blank">https://www.unidata.ucar.edu/s<wbr>oftware/netcdf/docs/netcdf_dat<wbr>a_set_components.html#coordina<wbr>te_variables</a><br><br></div>Best Practices:<br> <a href="https://www.unidata.ucar.edu/software/netcdf/docs/BestPractices.html" target="_blank">https://www.unidata.ucar.edu/s<wbr>oftware/netcdf/docs/BestPracti<wbr>ces.html</a><br><div><div><br></div><div>A 'coordinate variable' (CV) is a "<b>convention</b> that such variables should be treated in a special way by software using this library." (eg: NCL) In short, a CV is a one-dimensional array (vector) containing monotonically {in/de}creasing numeric values. Further, the variable name should match the dimension name: time(time), lat(lat), longitude(longitude), p(p), etc<br><br>Note: There is nothing in the netCDF software to preclude associating an _FillValue or missing_value attribute with a coordinate-variable. Still, the best practices recommends that a CV should contain no _FillValue values. Hence, no need for and _FillValue attribute.<br><br></div><div>The following is a 'variable that contains coordinates'. Further, the 'units' attribute is definitely not CF conforming.<br></div><div><div><br> double time(storm, time) ; ; 'time' is a 2D variable and a dimension name.<br></div><div> <wbr> ; best practices would say this is not recommended<br></div><div> time:long_name = "time" ;<br> time:standard_name = "time" ;<br> time:units = "days after " ; <=== not CF conforming<br><br></div><div>===================<br><br></div><div>'storm' is a dimension name with no 'values' associated. There is nothing wrong with this but I suggest:<br> <br></div><div>--- NCL<br></div><div> nstorm = 310<br></div><div> storm = toshort(ispan(1, nstorm,1) ) <br></div><div> storm!0 = "storm"<br></div><div> storm@long_name = "storm id: ALL storms"<br></div><div>--- nc file<br></div><div> short storm(storm)<br></div><div> storm: long_name = "storm id: ALL storms"<br><br></div><div>Also, suggested is a name change as you mentioned:<br></div><div><br> TIME(storm, time) ; <br><br></div><div>Thing is that 'time' varies with *each* storm (100 for storm 1, 3 for storm 2, ...)<br><br></div><div>To me this is analogous to station data (time series) where each station may have a different time series length.<br><br></div><div>Maybe, the following would be useful in guiding the development of your netCDF file<br></div><div><br> <a href="https://www.unidata.ucar.edu/software/thredds/current/netcdf-java/reference/FeatureDatasets/CFpointImplement.html" target="_blank">https://www.unidata.ucar.edu/s<wbr>oftware/thredds/current/netcdf<wbr>-java/reference/FeatureDataset<wbr>s/CFpointImplement.html</a><br><br></div><div>I think that the "<b>Trajectory data</b>" category would be appropriate.<br><br>====<br></div><div>I have not dealt with this issue so I can't suggest a specific approach.<br><br></div><div>Hopefully, someone else will chime in.<br><br></div><div>Happy New Year<br></div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="m_-4174262033547365150h5">On Fri, Jan 5, 2018 at 9:39 AM, Carl Schreck via ncl-talk <span dir="ltr"><<a href="mailto:ncl-talk@ucar.edu" target="_blank">ncl-talk@ucar.edu</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="m_-4174262033547365150h5"><div dir="auto">Sorry, I misframed the question.... We know the files aren't cf compliant yet, we're just curious if there's a particular version ncl uses. More importantly, if anyone has experience or examples making trajectory files with trajectories of different lengths, that'd be helpful. Thanks! <br><br><div data-smartmail="gmail_signature">--<br>Sent from my phone. Sorry for the brevity. </div></div><div class="m_-4174262033547365150m_7842598831510802482HOEnZb"><div class="m_-4174262033547365150m_7842598831510802482h5"><div class="gmail_extra"><br><div class="gmail_quote">On Jan 5, 2018 10:56 AM, "Carl Schreck" <<a href="mailto:cjschrec@ncsu.edu" target="_blank">cjschrec@ncsu.edu</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Which CF convention version does NCL primarily use? <div><br></div><div>Ken Knapp (CC'd) is developing a new version of IBTrACS (beta version attached) and says it's CF 1.6/1.7 compliant. But he uses "time" as one of the named dimensions of many of the variables, but also uses "time" as a 2-d variable, not related to that dimension.<div><br></div><div>When I try to read any of the variables that have time as a dimension, I get this error:</div><div><br></div><div><font face="monospace, monospace">fatal:_NclOneDValCoordDataCrea<wbr>te: Number of dimensions is greater than one, could not create coordinate data object</font></div><div><br></div><div>I also cannot write a _FillValue to the time variable since NCL believes time to be a coordinate variable. (no error provided, it just doesn't do it).</div><div><br></div><div>It'd probably be cleaner to just rename one of the "times", but we were just curious if the current format runs afoul of the CF convention or whether NCL is adding the extra limitations.</div><div><br></div><div>Thanks!</div><div>Carl<br clear="all"><div><br></div>-- <br><div class="m_-4174262033547365150m_7842598831510802482m_2839665025626874521m_3437537358270886559gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><br><table style="background-color:transparent;max-width:100%;border-collapse:collapse;color:rgb(51,51,51);font-size:14px;border:3px solid rgb(170,170,170);font-family:Times;line-height:12px" cellspacing="2" cellpadding="2" border="0"><tbody><tr><td align="center" width="71" height="71"><span style="font-size:11px"><span style="font-family:arial,helvetica,sans-serif"><a href="https://ncics.org/" style="color:rgb(17,85,204)" target="_blank"><img src="https://ncics.org/ncics/img/NCICS_logo-131x131.png"></a></span></span></td><td valign="top"><span style="font-size:11px"><span style="font-family:arial,helvetica,sans-serif"><b>Carl J. 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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><span style="font-family:comic sans ms,sans-serif"><b>Ken Knapp, Ph.D.</b></span><br style="font-family:comic sans ms,sans-serif"><span><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:13px;font-family:Arial;vertical-align:baseline;white-space:pre-wrap">Meteorologist, Center for Weather and Climate</span></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-family:Arial;font-size:13px;white-space:pre-wrap;line-height:1.38">NOAA National Centers for Environmental Information</span><br></p><p dir="ltr" style="line-height:1.38;margin-top:0pt;margin-bottom:0pt"><span style="font-size:13px;font-family:Arial;font-style:italic;vertical-align:baseline;white-space:pre-wrap">formerly NOAA’s National Climatic Data Center </span></p><div><span style="vertical-align:baseline"><font face="Arial"><span style="font-size:13px;white-space:pre-wrap"><br></span></font></span></div><div><span style="vertical-align:baseline"><font face="Arial"><span style="font-size:13px;white-space:pre-wrap">E/NE31</span></font><br></span></div></span></div><div dir="ltr">151 Patton Ave<br>Asheville, NC 28801<br>828-271-4339 (voice) 828-271-4328 (fax)<br><span><font color="#888888"><a href="http://www.cyclonecenter.org/" target="_blank">http://www.cyclonecenter.org/</a> <b>where your clicks count!</b></font></span><br><br><font face="comic sans ms, sans-serif">"Leave this world a little better than you found it."<br> ---Baden-Powell's Last Message (1945)</font><br><br><font size="1">Disclaimer:<br>The opinions expressed in this email are those of the author.
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