[python #VFQ-902488]: Questions about Siphon API

Greetings!

I think part of the problem is a server misconfiguration. If I click through 
the HTML catalog 
(https://tds.ucar.edu/thredds/catalog/esgcet/382/cordex.mbcn-Daymet.NAM-22i.ann.CanRCM4.CanESM2.rcp45.tmax.v20220107.html)
 on the first dataset, I don't see netCDF subset listed. Only HTTP and GridFTP. 
With that said, the second dataset does show NCSS on the list and it doesn't 
work with Siphon either. My best guess is that you're seeing one of:

  https://github.com/Unidata/siphon/issues/715
  https://github.com/Unidata/siphon/issues/734

There is no way to get netCDF header information with NCSS--in fact, NCSS will 
work on datasets that aren't originally netCDF (like GRIB), so there's not a 
direct mapping to netCDF on disk. The NCSS() instance returned by subset() does 
have a .metadata attribute which represents the metadata available through the 
NCSS service; this includes things like the lat/lon domain, time bounds, 
available variables, etc.

Hope this helps,

Ryan

> Hi Ryan,
> 
> 
> I've been tasked with creating some python examples for programmatically
> accessing data from CISL/ISD Thredds Data Servers.    I have a couple of
> questions at the bottom of the email, but first some background.
> 
> 
> I'm working from this example I found in the Siphon documentation, trying
> to create a NetCDF subset with just the data for Boulder, Colorado:
> 
> https://unidata.github.io/siphon/latest/examples/ncss/NCSS_Example.html
> 
> ...and I'm trying to use this particular Thredds Catalog URL:
> 
> https://tds.ucar.edu/thredds/catalog/esgcet/382/cordex.mbcn-Daymet.NAM-22i.ann.CanRCM4.CanESM2.rcp45.tmax.v20220107.xml
> 
> 
> But when I try to create a NetCDF Subset, Siphon complains that the Subset
> Service is not available:
> 
> 
> 
> 
> So a couple of questions:
> 
> 1. Is this a server configuration error, or am I missing a step
> somewhere?
> 2. If a user is unaware of the time or space coordinate ranges for a
> NetCDF file, does Siphon provide a way for querying the NetCDF header
> information without first downloading the file?
> 

Ticket Details
===================
Ticket ID: VFQ-902488
Department: Support Python
Priority: Low
Status: Closed
===================
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