[gradsusr] Problem Displaying Templated Multiple File Data

Wed Aug 31 09:14:06 EDT 2011

Jennifer,
Interesting.  I tried UNPACK without third argument and got the following
error, for example:

ga-> d tmp-273.15
Warning: Could not retrieve add offset -- setting to 0.0
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Warning: Could not retrieve add offset -- setting to 0.0
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10
Contouring: -560 to -480 interval 10

However, with offset value of 512.81 included, it works correctly:

ga-> d tmp-273.15
Contouring: -50 to 30 interval 10
Contouring: -40 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10
Contouring: -50 to 30 interval 10

Stephen Mc

On Tue, Aug 30, 2011 at 6:31 PM, Jennifer Adams <jma at cola.iges.org> wrote:

> Glad to hear it is working. Just for the record, the third argument to the
> UNPACK entry is not necessary, the two attribute names are all you
> need. --Jennifer
>
> On Aug 30, 2011, at 5:52 PM, Stephen McMillan wrote:
>
> Hi Jennifer,
>
> I did a "q attr" check on the 1948 file and found this:
> air Float32 add_offset 512.81
> air Float32 scale_factor 0.01
>
> Trying to follow example in the GrADS documentation and a few
> trial-and-error runs, here's my revised descriptor:
>
> DSET h:\cdf\dailymeans\air.sig995.%y4.nc
> TITLE Daily Air Temperature Sig995 01Jan1948-current
> DTYPE netcdf
> OPTIONS template yrev
> UNDEF -9.99e+33
> UNPACK scale_factor add_offset 512.81
> XDEF 144 linear 0 2.5
> YDEF 73 linear -90 2.5
> ZDEF 1 linear 0 1
> TDEF 3653 linear 01jan1948 1dy
> VARS 1
> air=>tmp 0 t,y,x  Mean Daily Air Temperature at sigma level 995 (degK)
> ENDVARS
>
> Initially, after re-running, the numbers looked "okay" (a reasonable range)
> but I noticed they were upside-down mirror images of what I got using yearly
> files separately.  So I added the "yrev" OPTIONS keyword and that appears to
> have fixed it.
>
> I believe everything works correctly now, so thanks for pointing me in the
> right direction!
>
> Stephen McMillan
>
>
> On Tue, Aug 30, 2011 at 4:40 PM, Jennifer Adams <jma at cola.iges.org> wrote:
>
>> Looks like you need the UNPACK entry in your descriptor file. Check your
>> netcdf files for scale_factor and add_offset attributes.
>> --Jennifer
>>
>> On Aug 30, 2011, at 4:31 PM, Stephen McMillan wrote:
>>
>> I am having a problem correctly displaying multiple file data using a
>> template control file.  My objective is to open, for example, the set of
>> daily air temperature data files (in yearly files) from 1948 to current as a
>> single file, then display/analyze the data as needed without having to open
>> each file separately.  Contents of control file
>> (air.sig995.daily.1948-.ctl):
>>
>> DSET h:\cdf\dailymeans\air.sig995.%y4.nc
>> TITLE Daily Air Temperature Sig995 01Jan1948-current
>> DTYPE netcdf
>> OPTIONS template
>> UNDEF -9.99e+33
>> XDEF 144 linear 0 2.5
>> YDEF 73 linear -90 2.5
>> ZDEF 1 linear 0 1
>> TDEF 3653 linear 01jan1948 1dy
>> VARS 1
>> air=>tmp 0 t,y,x  Mean Daily Air Temperature at sigma level 995 (degK)
>> ENDVARS
>>
>> For test purposes, I set TDEF to cover only the first 10 years.  When I
>> launch it in GrADS, it opens "normally" but the data displays with values
>> much lower than expected.  Following is the GrADS session transcript:
>>
>> Grid Analysis and Display System (GrADS) Version 2.0.a7.oga.3
>> Copyright (c) 1988-2008 by Brian Doty and the
>> Institute for Global Environment and Society (IGES)
>> GrADS comes with ABSOLUTELY NO WARRANTY
>> See file COPYRIGHT for more information
>>
>> Config: v2.0.a7.oga.3 little-endian readline printim grib2 netcdf hdf4-sds
>> hdf5
>> opendap-grids,stn athena geotiff
>> Issue 'q config' command for more information.
>> Loading User Defined Extensions table </bin/gex/udxt> ... ok.
>> GX Package Initialization: Size = 11 8.5
>> ga-> open c:\cdf\dailymeans\air.sig995.daily.1948-.ctl
>> Scanning description file:  c:\cdf\dailymeans\air.sig995.daily.1948-.ctl
>> Data file h:\cdf\dailymeans\air.sig995.%y4.nc is open as file 1
>> LON set to 0 360
>> LAT set to -90 90
>> LEV set to 0 0
>> Time values set: 1948:1:1:0 1948:1:1:0
>> E set to 1 1
>> ga-> q ctlinfo
>> dset h:\cdf\dailymeans\air.sig995.%y4.nc
>> title Daily Air Temperature Sig995 01Jan1948-current
>> undef -9.99e+33
>>  dtype netcdf
>> xdef 144 linear 0 2.5
>> ydef 73 linear -90 2.5
>> zdef 1 linear 0 1
>> tdef 3653 linear 00Z01JAN1948 1440mn
>> vars 1
>> air=>tmp  0  t,y,x  Mean Daily Air Temperature at sigma level 995 (degK)
>> endvars
>> ga-> set time 25dec1953 5jan1954
>> Time values set: 1953:12:25:0 1954:1:5:0
>> ga-> d tmp-273.15
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> Contouring: -29000 to -21000 interval 1000
>> ga->
>> ______________________________________
>>
>> I was expecting data to display in deg C, i.e., in the range of roughly
>> -50 to 30, which is what I would get if I open a yearly file separately.  I
>> also noticed that the display pattern itself is not consistent with the
>> original files' data.  The data folder contains valid yearly files from 1948
>> through 2011.
>>
>> I did search the gradsusr.org archives for help, but could not find a
>> solution.  I would appreciate someone suggesting a fix.  I am using
>> Opengrads Version 2.0.a7.oga.3 on a Windows XP.
>>
>> Stephen McMillan
>>
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>>
>>  --
>> Jennifer M. Adams
>> IGES/COLA
>> 4041 Powder Mill Road, Suite 302
>> Calverton, MD 20705
>> jma at cola.iges.org
>>
>>
>>
>>
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>>
>>
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>
> --
> Jennifer M. Adams
> IGES/COLA
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705
> jma at cola.iges.org
>
>
>
>
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>

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