Re: [ncl-talk] FillValue problem?

Interesting...I get slightly different but as inexplicable results.

I get _FillValue=-999. using ncdump, as you found. However, running
your scriptlet, I get _FillValue=0, not -999. nor -4.4755859375.

This is an Intel Mac 10.5.8.
On Nov 12, 2009, at 1:49 PM, David B. Reusch wrote:

> I have run into a situation with NCL and _FillValue that completely
> baffles me. The short version is that the _FillValue should be -999.
> but NCL is assigning -4.4755859375 instead. I've included an ncdump,
> the NCL script, and the script output below. I've put the netCDF file
> (sie_1973-2001.nc) in the incoming dir of ftp.cgd.ucar.edu (it's about
> 500kb). Is this a bug or am I just missing something obvious? This
> is
> running on a PPC Mac at OS 10.5.8 with NCL 5.1.1.
>
> Thanks,
> Dave
>
> An ncdump -h of the file I am reading:
>
> netcdf sie_1973-2001 {
> dimensions:
> time = 348 ;
> lon = 360 ;
> mon = 12 ;
> variables:
> float time(time) ;
> time:desc = "time" ;
> time:long_name = "Decimal Year" ;
> time:units = "year" ;
> time:_FillValue = -999. ;
> float year(time) ;
> year:desc = "Year" ;
> year:long_name = "Year" ;
> year:units = "year" ;
> year:_FillValue = -999. ;
> float month(time) ;
> month:desc = "month" ;
> month:long_name = "Month" ;
> month:units = "month" ;
> month:_FillValue = -999. ;
> float lon(lon) ;
> lon:desc = "Longitude" ;
> lon:long_name = "Longitude" ;
> lon:units = "degrees" ;
> lon:_FillValue = -999. ;
> float mon(mon) ;
> mon:desc = "Month" ;
> mon:long_name = "Month Number for Means" ;
> mon:units = "month" ;
> mon:_FillValue = -999. ;
> float sie(time, lon) ;
> sie:desc = "Sea Ice Edge" ;
> sie:long_name = "Latitude of Sea Ice Edge" ;
> sie:units = "degrees" ;
> sie:_FillValue = -999. ;
> float sie_mon(mon, lon) ;
> sie_mon:desc = "Mean Sea Ice Edge" ;
> sie_mon:long_name = "Mean Latitude of Sea Ice Edge" ;
> sie_mon:units = "degrees" ;
> sie_mon:_FillValue = -999. ;
>
> // global attributes:
> :origin = "HadISST1" ;
> }
>
> My stripped-down NCL script is as simple as can be:
> begin
> nc = addfile( "sie_1973-2001.nc", "r" )
> SIE = nc->sie
> printVarSummary(SIE)
> SIE@_FillValue = -999.
> printVarSummary(SIE)
> end
>
> And yet my results are completely puzzling:
> Copyright (C) 1995-2009 - All Rights Reserved
> University Corporation for Atmospheric Research
> NCAR Command Language Version 5.1.1
> The use of this software is governed by a License Agreement.
> See http://www.ncl.ucar.edu/ for more details.
>
>
> Variable: SIE
> Type: float
> Total Size: 501120 bytes
> 125280 values
> Number of Dimensions: 2
> Dimensions and sizes: [time | 348] x [lon | 360]
> Coordinates:
> time: [1973.042..2001.958]
> lon: [-179.5..179.5]
> Number Of Attributes: 4
> desc : Sea Ice Edge
> long_name : Latitude of Sea Ice Edge
> units : degrees
> _FillValue : -4.4755859375
>
>
> Variable: SIE
> Type: float
> Total Size: 501120 bytes
> 125280 values
> Number of Dimensions: 2
> Dimensions and sizes: [time | 348] x [lon | 360]
> Coordinates:
> time: [1973.042..2001.958]
> lon: [-179.5..179.5]
> Number Of Attributes: 4
> desc : Sea Ice Edge
> long_name : Latitude of Sea Ice Edge
> units : degrees
> _FillValue : -999
>
> --
> 517 Deike Building
> Earth & Environmental Systems Institute
> Penn State University
> University Park, PA 16802
>
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Received on Thu Nov 12 14:00:50 2009