[THREDDS #OGW-706975]: Names in dimensions variables

Greetings Fernando,

The data you are getting from the TDS is originally stored in GRIB format, 
which is
simply a collection of individual GRIB messages. If you are not super familiar 
with GRIB,
each message is basically a 2D horizontal slice of data. netCDF-Java, which the 
TDS is
built upon, looks at all of these individual slices of data and tries to look 
at them as a
collection of (generally) four dimensional data (time, x, y, z). The dimensions 
are 
constructed on the fly by netCDF-Java in the order they are encountered while 
reading
through the messages. Because we do not receive the grids in a set order, the 
order in 
which the coordinates are created can and, and you've seen, does change.

Currently there isn't a way to ensure the time dimension or coordinate variable 
associated
with a data variable is always called, say, "time" and not "time1". However, 
the metadata
of the data variable will always give you the correct name to use if you 
examine the 
variable attribute "coordinates".

If you absolutely need the time dimension and coordinate variable to be called 
time, then
you will (unfortunately) need to post-process the netCDF file you get back from 
the TDS.
A combination of netCDF-Java and NcML can make this process easy to do in an 
automated
way, and it can be quite fast. I'd be happy to help you find a solution, but 
I'd need to know a
bit more about what you are looking to do with the netCDF file once you have it 
downloaded.

Cheers,

Sean

> Hi my name is Fernando Mata from the University of Costa Rica and we are
> currently using your data in order to createa forecast service for people
> living in the coast. Lately we have been having some issues regarding the
> name of the dimensions variables in the data downloaded from your thredds
> servers, the issue is with the name of the time variable that sometimes is
> "time1" or "time", is this the normal behavior? If that is the case, is
> there a method to get the var with a consistent name?
> Attached are two example files from different days downloaded from the
> thredds server, both are outputs from the WW3 model.
> 
> thanks in advance and have a good day.
> --
> Fernando Mata Mora

Ticket Details
===================
Ticket ID: OGW-706975
Department: Support THREDDS
Priority: Normal
Status: Open
===================
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