[netcdfgroup] problem in netcdf file

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: [netcdfgroup] problem in netcdf file
• From: Sujata Mandke <sujatamandke@xxxxxxxxx>
• Date: Thu, 21 Jan 2016 11:55:20 +0530

Dear Group
  I have following problem in reading
netcdf file. This data file is downloaded
from CMIP5 project. It is daily precipitation
of GFDL HIRAM180 model simulation
for the period 1979-2008. The problem is
as follows
----------------------------------------------
1. File-"pr_day_GFDL-HIRAM-C180_amip_r1i1p1_19790101-20081231.nc"
is opened in grads using "sfdopen"
2. When "pr" (which is in units
of (kg m2 s-2 )  is plotted, it is found that range is incorrect.

3. Range of "pr" after multiplying by 86400.0
  (to convert to units of mm/day)
is one oreder of magnitude higher than expected.
  as shown below.
ga-> d pr
Contouring: 0 to 0.0035 interval 0.0005
ga-> d pr*86400.0
Contouring: 0 to 330 interval 30

4. in grads >q undef gives
Output undef value is set to -999000000.000000

Whereas header of netcdf file obtained using "ncdump"-
"pr_day_GFDL-HIRAM-C180_amip_r1i1p1_19790101-20081231.nc"
shows undefine as
--------------------------------
pr:missing_value = 1.e+20f ;
pr:_FillValue = 1.e+20f ;
--------------------------------
5. Also shaded plot shows value of
variable "pr" less than zero over
some regions. (precipitation can
not be less than zero).
--------------------------------------
-- 
Dr. Sujata Mandke
Scientist, Indian Institute of Tropical Metetorology
PUNE-INDIA.

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  • Re: [netcdfgroup] problem in netcdf file
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