<div dir="ltr"><div><div><div>As you know, typically for climate and forecast related files, the Climate and Forecast convention is followed.<br><br>---<br><a href="http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/cf-conventions-multi.html">http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/cf-conventions-multi.html</a><br>---<br></div><div>[0] To my knowledge, there is no "higher standard" ... except me!<br></div><div><br></div>[1] Though not CF specified, 'time' should be double". Time should always be as precise as possible.<br></div><div> Though not required, I suggest the calendar attribute be added.<br><br> double time(time) ;<br> time:long_name = "reference time" ;<br> time:units = "hours since 1800-01-01 00:00:00" ; < *any* reference time<br> time:calendar = "gregorian" ;<br> time:bounds = "time_bnds" ; <=== if averaging involved .<br><br></div> In addition, I suggest the inclusion of human readable auxiliary time variables. <br> This makes 'time' more friendly to people who do not like dealing with those<em> nonsensical </em><span class=""><em></em></span>time values.<br> The CESM netCDF uses:<br><br> int date(time) ;<br> date:long_name = "current date (YYYYMMDD)" ;<br><br> int datesec(time) ;<br> datesec:long_name = "current seconds of current date" ; ; hours,minutes ... can be derived from this<br><br></div> Note: there is no 'units' attribute associated with these auxiliary time variables because the units would not be recognized by udunits<br><div><br><div>[2] time,lev,lat,lon ..... purely arbitrary .... they are short<br><br></div><div>[3] My personal rule, do not use _FillValue=0.0<br></div><div> Always ... _FillValue should be the same type as the variable with which it is associated.<br></div><div> If the variable is type 'short', the _FillValue should be type short.<br><br></div><div> If _FillValue is present, also include the missing_value attribute. This allows assorted applications which recognize<br></div><div> different conventions.<br><br> <a href="http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/ch02s05.html#missing-data">http://cfconventions.org/Data/cf-conventions/cf-conventions-1.7/build/ch02s05.html#missing-data</a><br><br></div><div>[4] Always include the convention being followed in the file attributes.<br><br></div><div> Conventions = "CF-1.?"<br></div><div><br></div><div>[5] <a href="https://climatedataguide.ucar.edu/climate-data-tools-and-analysis/netcdf-overview">https://climatedataguide.ucar.edu/climate-data-tools-and-analysis/netcdf-overview</a><br><br></div><div> There is a link to a CF convention checker. It works well but can take time.<br></div><div> Maybe NCDC could get it and download on their machines.<br><br></div><div>HTH<br></div><div>D<br></div><div> <br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Sep 9, 2014 at 7:29 AM, Carl Schreck <span dir="ltr"><<a href="mailto:cjschrec@ncsu.edu" target="_blank">cjschrec@ncsu.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">Apologies for a slightly off-topic question, but I want to draw on the expertise on this list.<div><br></div><div>I've noticed that many of the netCDF datasets I download, esp. those from ESRL, have similar attributes that go beyond just CF-compliance. A few examples:</div><div><br></div><div>- time is always a double instead of a float</div><div>- time is usually in units of days or hours since 1800</div><div>- _FillValue isn't zero</div><div>- The coordinate arrays are named time, level, lat, lon.</div><div><br></div><div>Is there a higher standard that dictates these practices? I ask here because NCL seems to play a little nicer with these files (esp. time as a double). My goal is to provide feedback to the data producers here at NCDC so that they can produce netCDF files that are as easily accessible as possible.</div><div><br></div><div> Thanks!</div><div> Carl<br><div><div><br></div>-- <br><div dir="ltr"><br><table style="background-color:transparent;max-width:100%;border-collapse:collapse;border-spacing:0px;color:rgb(51,51,51);font-size:14px;border:3px solid rgb(170,170,170);font-family:Times;line-height:12px" border="0" cellpadding="2" cellspacing="2"><tbody><tr><td height="71" width="71" align="center"><span style="font-size:11px"><span style="font-family:arial,helvetica,sans-serif"><a href="http://www.cicsnc.org/" style="color:rgb(38,58,143);text-decoration:none;font-weight:bold" target="_blank"><img src="http://www.cicsnc.org/assets/images/cicsnc-logo.png" height="94" width="96"></a><a href="http://www.researcherid.com/rid/B-8711-2011" target="_blank"><br></a></span></span><a href="http://www.researcherid.com/rid/B-8711-2011" target="_blank"><img src="http://labs.researcherid.com/mashlets/badge/rid-idsymbol4.gif" alt="http://www.researcherid.com/rid/B-8711-2011" height="56" width="96"></a><br></td><td valign="top"><span style="font-size:11px"><span style="font-family:arial,helvetica,sans-serif"><b>Carl J. Schreck III, PhD</b><br><b>Research Associate</b><br><a href="http://cicsnc.org/" style="color:rgb(38,58,143);text-decoration:none;font-weight:bold" target="_blank">Cooperative Institute for Climate and Satellites NC</a><br><a href="http://ncsu.edu/" style="color:rgb(38,58,143);text-decoration:none;font-weight:bold" target="_blank">North Carolina State University</a><br><a href="http://ncdc.noaa.gov/" style="color:rgb(38,58,143);text-decoration:none;font-weight:bold" target="_blank">NOAA's National Climatic Data Center</a><br>151 Patton Ave, Asheville, NC 28801<br>e: </span></span><a href="mailto:cjschrec@ncsu.edu" style="color:rgb(38,58,143);font-family:arial,helvetica,sans-serif;font-size:11px;text-decoration:none;font-weight:bold" target="_blank">cjschrec@ncsu.edu</a><br style="font-family:arial,helvetica,sans-serif;font-size:11px"><span style="font-size:11px"><span style="font-family:arial,helvetica,sans-serif">o: <a value="+18282573140" style="color:rgb(17,85,204)">+1 828 257 3140</a><br></span></span><a href="http://cyclonecenter.org/" style="color:rgb(38,58,143);font-family:arial,helvetica,sans-serif;font-size:11px;text-decoration:none;font-weight:bold" target="_blank">CycloneCenter.org: Help analyze tropical cyclones</a><br><a href="http://monitor.cicsnc.org/mjo/" style="color:rgb(38,58,143);font-family:arial,helvetica,sans-serif;font-size:11px;text-decoration:none;font-weight:bold" target="_blank">monitor.cicsnc.org/mjo: See recent MJO diagnostics</a><br style="font-family:arial,helvetica,sans-serif;font-size:11px"></td></tr></tbody></table></div>
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