<div dir="ltr"><div><div><div>DaveA, you should have been a lawyer!!! :-)<br><br></div>That is a bug. I have filed a JIRA ticket (NCL-2690) for 6.5.0. <br><br>I agree with Denise. Forcing the value associated with the calendar attribute to lower case is a solution.<br><br></div></div>D<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Nov 16, 2017 at 5:30 AM, Denise Worthen - NOAA Affiliate <span dir="ltr"><<a href="mailto:denise.worthen@noaa.gov" target="_blank">denise.worthen@noaa.gov</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 class="gmail_default"><font face="verdana, sans-serif">Thanks everyone for your help. I agree Julian is an odd choice, but it wasn't mine (the file originates from MOM6 output). It did dawn on me about 30 minutes after hitting send that the problem was the case (JULIAN vs julian). Duh. </font></div><div class="gmail_default"><font face="verdana, sans-serif"><br></font></div><div class="gmail_default"><font face="verdana, sans-serif">I've been able to correct the issue by using timeCalendar = f->time@calendar followed by timeval@calendar=str_lower(<wbr>timeCalendar).</font></div><div class="gmail_default"><font face="verdana, sans-serif"><br></font></div><div class="gmail_default"><font face="verdana, sans-serif">This seems like a good thing to do by default since cd_calendar and cd_string expect lower case.</font></div><span class="HOEnZb"><font color="#888888"><div class="gmail_default"><font face="verdana, sans-serif"><br></font></div><div class="gmail_default"><font face="verdana, sans-serif">Denise.</font></div>
<div class="gmail_default"><font face="verdana, sans-serif"><br></font></div><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div></font></span></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Nov 15, 2017 at 8:57 PM, Dave Allured - NOAA Affiliate <span dir="ltr"><<a href="mailto:dave.allured@noaa.gov" target="_blank">dave.allured@noaa.gov</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 class="gmail_extra">Dennis,<br><br>Ah, thanks for finding the actual problem. However, in CF section 2.6, "Attributes", VALUES of character attributes have a different rule than attribute NAMES:<br><br> "... When this standard defines string attributes that may take</div><div class="gmail_extra"> various prescribed values, the possible values are generally</div><div class="gmail_extra"> given in lower case. However, applications programs should</div><div class="gmail_extra"> not be sensitive to case in these attributes ..."</div><div class="gmail_extra"><br></div><div class="gmail_extra">So "JULIAN" and "julian" should both be correct, and the file is CF compliant. Regardless, the best interim fix for Denise is to convert the calendar attribute to lowercase, before using date functions like cd_calendar.</div><div class="gmail_extra"><br></div><div class="gmail_extra">I agree that attribute NAMES such as "units" and "calendar" must be lower case according to CF.</div><span class="m_-7161974617239101371HOEnZb"><font color="#888888"><div class="gmail_extra"><br></div><div class="gmail_extra">--Dave</div></font></span><div><div class="m_-7161974617239101371h5"><div class="gmail_extra"><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Nov 15, 2017 at 5:59 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"><div><div><div><div><div><div>Ummm, I don't this is a bug. <br><br>I think the file does not adhere to the Climate and Forecast netCDF convention<br><br></div>[1] CF Convention: calendar attribute<br> <br> <a href="http://cfconventions.org/Data/cf-conventions/cf-conventions-1.6/build/cf-conventions.html#calendar" target="_blank">http://cfconventions.org/Data/<wbr>cf-conventions/cf-conventions-<wbr>1.6/build/cf-conventions.html#<wbr>calendar</a><br><br></div>[2] The recognized <b>calendar </b>attributes are all lower case. No mention is made of 'case insensitivity.'<br></div> As an example: the <b>units </b>attribute is lower case; UNITS, Units etc are <b>*not* </b>recognized.<br><br></div>[3] See attached script. <br><br></div>%> ncl test_time_julian.ncl<br><br>------<br><br>Variable: C<br>Type: float<br>Total Size: 24 bytes<br> 6 values<br>Number of Dimensions: 2<br>Dimensions and sizes: [1] x [6]<br>Coordinates: <br>Number Of Attributes: 1<br> <b>calendar : JULIAN<br>(0,0) 2015<br>(0,1) 5<br>(0,2) 13<br>(0,3) 12</b><br>(0,4) 0<br>(0,5) 0<br>(0) =========<br><br><br>Variable: c<br>Type: float<br>Total Size: 24 bytes<br> 6 values<br>Number of Dimensions: 2<br>Dimensions and sizes: [1] x [6]<br>Coordinates: <br>Number Of Attributes: 1<br> <b>calendar : julian<br>(0,0) 2015<br>(0,1) 4<br>(0,2) 30<br>(0,3) 12</b><br>(0,4) 0<br>(0,5) 0<br><br></div>The latter matches ferret and (more important) DaveA's hand calculation.<br><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Nov 15, 2017 at 3:21 PM, Dave Allured - NOAA Affiliate <span dir="ltr"><<a href="mailto:dave.allured@noaa.gov" target="_blank">dave.allured@noaa.gov</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">Denise,<div><br></div><div>Your sample file uses the Julian calendar. In my experience the Julian calendar is rarely used in climate sciences, and software implementations are not well vetted. The best long term solution might be to switch to the Gregorian calendar, if that is not contrary to your current application.</div><div><br></div><div>Also your time base is "hours since 0001-01-01 00:00:00". Using a base date before the Julian to Gregorian change in year 1582 exposes you to a particular kind of software problem. You might get better results if you can switch to a base date in the near past, such as 1900-1-1 or 2000-1-1, regardless of which calendar system is selected.</div><div><br></div><div>For what it's worth, my hand calculation for Julian 17657580 hours since 1-1-1 0:0:0 gets 2015 April 30 12:00. This agrees with your ferret result.</div><span class="m_-7161974617239101371m_1059000621246521930m_-4500736619975034908m_-8827451634815786714HOEnZb"><font color="#888888"><div><br></div><div>--Dave</div></font></span><div><div class="m_-7161974617239101371m_1059000621246521930m_-4500736619975034908m_-8827451634815786714h5"><div><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Nov 15, 2017 at 1:00 PM, Denise Worthen - NOAA Affiliate <span dir="ltr"><<a href="mailto:denise.worthen@noaa.gov" target="_blank">denise.worthen@noaa.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div style="font-family:verdana,sans-serif">Hi,</div><div style="font-family:verdana,sans-serif"><br></div><div style="font-family:verdana,sans-serif">I've used ncra to 'record average' a set of netcdf files. When I look at the file using ferret, the date in each file is correctly interpreted. </div><div style="font-family:verdana,sans-serif"><br></div><div style="font-family:verdana,sans-serif">When I use ncl, the dates in the file are interpreted incorrectly, either as a label (using cd_string) or just printing the value using cd_calendar.</div><div style="font-family:verdana,sans-serif"><br></div><div style="font-family:verdana,sans-serif">I've extracted out the time axis for a single timestep and attached it here. The correct value in this case should be april 30 2015.</div><div style="font-family:verdana,sans-serif"><br></div><div style="font-family:verdana,sans-serif">Using the following commands, it shows the date as 5-13-2015. This is also the label I get when using cd_string to label a plot in the original file. </div><div style="font-family:verdana,sans-serif"><br></div><div style="font-family:verdana,sans-serif">What have I got wrong?</div><div style="font-family:verdana,sans-serif">Denise.</div><div style="font-family:verdana,sans-serif"><br></div><div style="font-family:verdana,sans-serif"><br></div>load "$NCARG_ROOT/lib/ncarg/nclscri<wbr>pts/contrib/cd_string.ncl"<br><br>begin<br><br>f=addfile("<a href="http://timetest.nc" target="_blank">timetest.nc</a>","r")<br>timeval=f->time<br>timeUnits = f->time@units<br>timeCalendar = f->time@calendar<br>print(cd_calendar(timeval,0))<br>end</div></blockquote></div></div></div></div></div></blockquote></div></div></blockquote></div></div></div></div></div>
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