Re: [ferret_users] Preserving var attributes from opendap server

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Paulo,
Thank you for the report. It turns out that Ferret wasn't writing the 
add_offset attribute to the dataset, because of some issues with the 
particular combination of data types for the variable and the types of 
its attributes.  I have fixed this for the next release of Ferret.

A second problem comes up, though. The most-recent OPeNDAP library (used 
in Ferret v6.4), and also the Netcdf-4 libraries (to be used in future 
versions of Ferret beginning with v6.6) are not able to write the 
variable confidence_flag as a variable of type byte.  They are telling 
me that the variable "confidence_flag", which in the dataset is listed 
as having type "byte", cannot be written out in the "byte" data type. 
I'm getting an error on attempting to write it, "NetCDF: Numeric 
conversion not representable".  Apparently the byte data type is being 
treated as signed 1-byte value, which has a range of only -128 to 127. 
An un-signed byte type does exist in NetCDF-4 but currently it's not 
clear if the Fortran API for NetCDF allows for that.

I can ask about that for the Netcdf-4 libraries, but with the next 
Ferret release we will need to use the command

  SET VAR/OUTTYPE=short  confidence_flag

Ansley

Paulo B. Oliveira wrote:
> I'm willing to locally save a subset of sea surface temperature data
> from an opendap server, preserving the original 2 byte representation,
> but apparently the scaling of the local dataset is not correct. 
>
> Any hints would be appreciated.
>
> Regards,
>
> Paulo  
>   
>  ! NOAA/PMEL TMAP
>  ! FERRET v6.07  
>  ! Linux(g77) 2.4.21-32 - 08/29/07
>  ! 19-Jun-08 12:09     
>
> def sym bdir $1"http://www.ifremer.fr/cgi-bin/nph-dods/data/satellite/medspiration/l2p/eurdac/seviri_sst/2010/095";
> def sym dset $2"20100405-SEVIRI_SST-EUR-L2P-sst3mlml_20100405_1000-v01"
>
> use "($bdir)/($dset).nc.bz2"
>
> set reg/x=-14.0:-5.0/y=34:44
>
> set win/asp=1.5
> set viewp upper
>  shade sea_surface_temperature; go land_detail
>
> SET ATT/OUTPUT=all sea_surface_temperature
> SET VAR/OUTTYPE=input  sea_surface_temperature
> save/clob/file=($dset).cdf sea_surface_temperature
>
> SET ATT/OUTPUT=all confidence_flag
> SET VAR/OUTTYPE=input  confidence_flag
> save/app/file=($dset).cdf confidence_flag
>
> canc reg/all; canc data/all; canc mem/all
>
> use ($dset)
>
> set viewp lower
>  shade sea_surface_temperature; go land_detail
>
> quit