Re: Read Nexrad level II data in netcdf format

The "fatal:..." message is not correct. It is a warning.

fatal:Dimension size of attribute and right-hand side of assignment do
not match

f = addfile("prova.nc","r")

az=f->azimuthR
t=f->timeR
ng=f->numGatesR
el=f->elevationR
d=f->distanceR

dbz=f->Reflectivity
printVarSummary(dbz)

nr=f->numRadialsR
printVarSummary(nr)

Variable: dbz
Type: byte
Total Size: 7254720 bytes
             7254720 values
Number of Dimensions: 3
Dimensions and sizes: [scanR | 11] x [radialR | 360] x [gateR | 1832]
Coordinates:
Number Of Attributes: 10
   units : dBz
   long_name : Reflectivity
   missing_value : ( 0x01, 0x00 )
   signal_below_threshold : 0x00
   scale_factor : 0.5
   add_offset : -33
   _Unsigned : true
   range_folding_threshold : 50
   _CoordinateAxes : timeR elevationR azimuthR distanceR
   _FillValue : ( 0x01, 0x00 )

Variable: nr
Type: integer
Total Size: 44 bytes
             11 values
Number of Dimensions: 1
Dimensions and sizes: [scanR | 11]
Coordinates:
Number Of Attributes: 1
   long_name : number of valid radials in this scan

==========================
However ....

NCL is aware of COARDS and CF conventions. The conventions followed on
his file are

:Conventions = "_Coordinates"

I think the Warning is a result of a 'conflict' of conventions.
Note the missing_value attribute is length 2. I believe the
COARDS convention requires missing_value to be a scalar.
Same for _FillValue under the CF convention.

Also, note the the "dbz" is type byte.
You will have to multiply this value
by the scale_factor [0.5] to get the correct value.

Good luck

On 4/28/11 8:45 AM, Andrea Chini wrote:
> Hi,
>
> I'm trying to read a .nc file created from a nexrad level II data file
> with toolsUI-4.2.
>
>
>
> When I try to read some variables such as Reflectivity or Radial
> Velocity (datatype byte) I encounter this error:
>
>
> "fatal:Dimension size of attribute and right-hand side of assignment do
> not match"
>
>
> This is the script that I've written:
>
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
>
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
>
> begin
>
> f = addfile("prova.nc","r")
>
> az=f->azimuthR
>
> t=f->timeR
>
> ng=f->numGatesR
>
> el=f->elevationR
>
> d=f->distanceR
>
> nr=f->numRadialsR
>
> dbz=f->Reflectivity
>
> end
>
>
> The error is only related with the reading of reflectivity in this case.
>
>
> Thank's for your help.
>
>
> Andrea C.
>
>
>
>
> _______________________________________________
> ncl-talk mailing list
> List instructions, subscriber options, unsubscribe:
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Fri Apr 29 06:18:49 2011