Greetings Larry! I've taken a look at your file, and you are correct that the issue is that it is not CF compliant. I've attached an NcML file to this email, and if you place this in the same directory as your netCDF file and load it (the NcML file) into the IDV, things will work as you expect. This fix will allow you to use the IDV with your model out. Please keep in mind that this will not make it CF compliant, but rather "good enough" for the IDV. The main issue: The time variable, t, has a unit attribute set to hours and a attribute ReferenceTime set to the reference time - in order to be CF compliant, the reference time must be part of the unit: attribute unit : "hours since 1991-03-19 18:00:00" (see http://cf-pcmdi.llnl.gov/documents/cf-conventions/1.6/cf-conventions.html#time-coordinate) All this NcML file does is change the attribute unit on the time variable t. Note that if you want to use this on a different file, you will need to edit the second line of the NcML file to correctly reference the new netCDF file. To make life easier, you may want to contact the modeling group and see if they would fix the unit for t in their code. Also, I would strongly recommend that when working with this data, you use the "Predefined -> South America" projection and turn off the option "Auto-set Projection" - both are found under the Projections menu just above the main view window. If you don't do this, you will get some pretty funky artifacts due to the prime meridian. Cheers! Sean > Dear support-idv: > > I am unable to import a time-varying 2-d gridded netcdf variable into idv > and was wondering if you might have some advice as to what I'm doing wrong. > > For example, I am using the following netcdf file: > ftp://ftpext.usgs.gov/pub/wr/wa/vancouver/Mastin/Ash3d/3d_tephra_fall.nc > > I am attempting to read the 2-D, time-dependent variable cloud_load, whose > properties are given as follows when I type "ncdump -h" > > double cloud_load(t, lat, lon) ; > cloud_load:long_name = "Cloud Load" ; > cloud_load:units = "T/km2" ; > cloud_load:missing_value = "-9999.f" ; > cloud_load:_FillValue = -9999. ; > > When I open this file using the IDV data chooser, only three variables are > visible, as you can see in the attached screenshot: > > Deposit arrival time > Airborne ash arrival time > Cell area > > These variables are 2-D gridded, non-time dependent variables, having the > dimensions: > > double depotime(lat, lon) ; > double ash_arrival_time(lat, lon) ; > double area(lat, lon) ; > > The netcdf file contains several other variables with dimensions (t, lat, > lon), like cloud_load, but none of these show up. > > Our modeling group wrote the code that creates the netcdf file and we think > the file is nf-compliant. > > Do you think this is an issue involving compliance with netcdf conventions, > or is there a trick to viewing time-dependent gridded netcdf data that I > haven't yet found? > > Your help would be appreciated. > > Thanks, > > Larry Mastin > > > -- > U.S. Geological Survey > David A. Johnston Cascades Volcano Observatory > 1300 SE Cardinal Court, Bldg. 10, Suite 100 > Vancouver, WA 98683 USA > tel. (360) 993-8925 > fax (360) 993-8980 > > Ticket Details =================== Ticket ID: ALX-750694 Department: Support IDV Priority: Normal Status: Open
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