Matt,
When reading in original NCEP Reanalysis data, you need to use the add_offset
and the scale factor accompanying the data array to obtain the correct form of
the data. From your print statement I see that this particular data array has
both.
Here is a section of code that will convert the data to the correct form, and
change the array from short to float (easier to use NCL functions that way):
begin
fdir="/data/matt/reanalysis/"
fnam="air.2m.gauss.1987.nc"
f = addfile(fdir+fnam,"r")
air=f->air
printVarSummary(air)
airnew = new ((/dimsizes(air)/),float,1.e+20)
airnew = (/ (air*air@scale_factor)+air@add_offset /)
copyVarCoords(air,airnew) ;in contributed.ncl
delete(air)
printVarSummary(airnew)
end
That should do it. Hope that helps.
Adam
> Date: Wed, 06 Feb 2002 17:49:42 -0500
> From: Matt Fearon <matthew.fearon AT unh.edu>
> X-Accept-Language: en
> MIME-Version: 1.0
> To: ncl-talk AT UCAR.EDU
> Subject: reading NCEP reanalysis 4x times daily data
> Content-Transfer-Encoding: 7bit
>
> Dear NCL users:
>
> I am trying to read NCEP reanalysis 4x times daily data using
> NCL. I am working on sgi machine running irix 6.5. Here is
> my script for reading surface temperature;
>
> begin
>
> fdir="/data/matt/reanalysis/"
> fnam="air.2m.gauss.1987.nc"
> f = addfile(fdir+fnam,"r")
>
> air=f->air
> print(air(0,1:10,2))
>
> end
>
> here is the output from the print;
>
> Variable: air (subsection)
> Type: short
> Total Size: 20 bytes
> 10 values
> Number of Dimensions: 1
> Dimensions and sizes: [lat | 10]
> Coordinates:
> lat: [86.6531..69.5217]
> Number Of Attributes: 18
> lon : 3.75
> time : 17408952
> parent_stat : Individual Obs
> I
> statistic : Mean
> M
> level_desc : 2 m
> O
> dataset : NMC Reanalysis
> L
> var_desc : Air temperature
> A
> GRIB_name : TMP
> GRIB_id : 11
> least_significant_digit : 1
> precision : 2
> missing_value : 32766
> scale_factor : 0.01
> add_offset : 477.65
> units : degK
> actual_range : <ARRAY>
> valid_range : <ARRAY>
> long_name : 4xDaily Air temperature at 2 m
> (0) -23925
> (1) -22905
> (2) -22345
> (3) -21395
> (4) -21125
> (5) -20865
> (6) -20735
> (7) -20765
> (8) -20735
> (9) -20535
>
>
> The data is incorrect, but I am not sure why. Do I need to declare the
> array using new a certain way. Any suggestions would be greatly
> appreciated.
>
> thank you,
> Matt
>
>
-------------------------------------------------------------
Adam Phillips email: asphilli AT ucar.edu
Climate and Global Dynamics Division tel: (303) 497-1726
National Center for Atmospheric Research fax: (303) 497-1333
P.O. Box 3000
Boulder, CO 80307-3000 http://www.cgd.ucar.edu/~asphilli
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