Re: Ferret: station data shows no variables

[Jonathan Callahan <Jonathan.S.Callahan@xxxxxxxx>]

Andrea,

OPeNDAP sequences are not currently supported in Ferret.  There is a 
basic division in the OPeNDAP world between Sequence data (potentially 
nested, indeterminate length arrays) and Grid data (1D-4D constant 
length arrays).  Ferret's internal data model assumes Grid structure and 
uses the NetCDF API to access data.  The OPeNDAP libraries that Ferret 
is linked with do not yet support translation between Sequences and 
Grids although recent test releases of the libraries advertise that 
functionality.  We'll be testing these libraries this summer.

In the mean time, if you want to serve OPeNDAP Sequence data in LAS you 
must use the LAS database access code and create a driver that can 
access your sequence data and create an intermediate NetCDF file:

http://ferret.pmel.noaa.gov/LASdoc/serve/cache/25.html

We haven't yet written a generic OPeNDAP sequence driver but the Dapper 
driver described on the page above is very close to what one would look 
like if you (or anyone else) wants to write one.

It is our hope that OPeNDAP Sequence translation will be a robust part 
of the OPeNDAP libraries in the very near future.  At that point, Ferret 
will be able to read OPeNDAP sequences directly, at least for those 
unstructured Sequence data sources where translation into Grids works well.

I hope that fills you in enough to make intelligent choices.  You might 
consider posting again to the LAS Users list asking if anyone else has 
written an OPeNDAP sequence driver for LAS.


-- Jon


Andrea Fey wrote:

> I having trouble utilizing a station data set in Ferret. The dataset 
> I'd like to open is large: 
> http://nomads.ncdc.noaa.gov:9091/dods/IGRA_MONTHLY_RAOBS/igramon; a 
> single-station link is here: 
> http://nomads.ncdc.noaa.gov:9091/dods/IGRA_STATION_RAOBS/425/igra.72208. 
> I can open both of these, but when I "show data" there is nothing listed.
>
> I can open both of these in GrADS. My eventual goal is to add this 
> data to a LAS server, and when I run a script (addGDS.pl) against 
> either data set I get the following error message: DODS sequence not 
> supported at dds.y line 5.
>
> Could this be a metadata issue even though the data can be pulled into 
> GrADS? Any other ideas?
>
> Thanks.
> Andrea