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[IDV #CGA-206836]: Multiple trajectories in a single file

> Thanks, Yuan.  I was hoping to avoid the "multidimensional array" approach 
> since, with staggered (in time) trajectories, there are a lot of missing 
> data.  I can give it a try, though.  One follow- up question: your time 
> dimension example has "days since 1970-01-01 00:00:00".  Can I use epoch time 
> instead (seconds since 1970-01-01 00:00:00)?
> 
> - Adam
> 
> 
Yes, I don't see any problem with it.

Yuan
> -----Original Message-----
> From: Unidata IDV Support <address@hidden>
> Sent: Monday, August 29, 2022 4:41 PM
> To: Adam Houston <address@hidden>
> Cc: address@hidden; Adam Houston <address@hidden>
> Subject: [IDV #CGA-206836]: Multiple trajectories in a single file
> 
> Non-NU Email
> 
> > Finally got back to this and created an example netcdf file (attached) that 
> > adheres to the CF "Contiguous ragged array representation of trajectories" 
> > convention 
> > (https://urldefense.com/v3/__https://cfconventions.org/Data/cf-conventions/cf-conventions-1.9/cf-conventions.html*_contiguous_ragged_array_representation_of_trajectories__;Iw!!PvXuogZ4sRB2p-tU!FQkxrNIl_WKyfKN5sF5xntqoy0u-5-uBZCE1LLA_FWLl29bDz5t1yHTePbLfF7psbaythVz43Y-0-WKHIZynupg6rhU6vg$
> >   ).  I tried opening this in version 6.1 using "netcdf/GEMPAK Point data 
> > files" and "point cloud data (netcdf)" but neither appears to work (no 
> > errors but nothing happens).
> >
> > - Adam
> >
> >
> 
> Hi Adam,
> 
> The coordinates of your netCDF file need to be like the following:
> 
> double time(trajectory, obs) ;
> time:standard_name = "time";
> time:long_name = "time" ;
> time:units = "days since 1970-01-01 00:00:00" ;
> float lon(trajectory, obs) ;
> lon:standard_name = "longitude";
> lon:long_name = "longitude" ;
> lon:units = "degrees_east" ;
> float lat(trajectory, obs) ;
> lat:standard_name = "latitude";
> lat:long_name = "latitude" ;
> lat:units = "degrees_north" ;
> 
> For a file with multiple trajectories, we use two dimensions: trajectory and 
> obs, to define all trajectories. Here is the document:
> 
> https://urldefense.com/v3/__https://cfconventions.org/cf-conventions/cf-conventions.html*_multidimensional_array_representation_of_trajectories__;Iw!!PvXuogZ4sRB2p-tU!FQkxrNIl_WKyfKN5sF5xntqoy0u-5-uBZCE1LLA_FWLl29bDz5t1yHTePbLfF7psbaythVz43Y-0-WKHIZynupgwSt-yAQ$
> 
> Yuan
> 
> Ticket Details
> ===================
> Ticket ID: CGA-206836
> Department: Support IDV
> Priority: Normal
> Status: Open
> ===================
> NOTE: All email exchanges with Unidata User Support are recorded in the 
> Unidata inquiry tracking system and then made publicly available through the 
> web.  If you do not want to have your interactions made available in this 
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> 
> 
> 


Ticket Details
===================
Ticket ID: CGA-206836
Department: Support IDV
Priority: Normal
Status: Open
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.