reading CERES HDF

Katia Fernandes kfernbern at YAHOO.COM
Sun Jul 3 11:22:54 EDT 2005


Thank you very much, Jennifer.

I suspected I was dealing with something evil, but decided to give it a try
anyway.

I will try your suggestion and if it doesn't work, I will contact the data
providers. My next best option is reading it with some other software, what
I really didn't want to do.

thanks a lot again,

Kátia


>On Fri, 1 Jul 2005 21:39:48 -0400, Jennifer Adams <jma at COLA.IGES.ORG> wrote:
>Katia,
>Thanks for providing a clear and complete picture of your problem.
>Your descriptors look good, except you need "t,y,x" in the units
>field of your variable declaration, since the variable
>LW_Surface_Emissivity does vary in three dimensions, even if one of
>them is size 1. (For xdfopen, the units field of the variable
>declaration isn't used.) However, my hunch is that even with this
>change, all your hard work will not pay off because an HDF file with
>two variables of identical name but different size is ... diabolical.
>I don't even know how you could create a file like that, and I'm
>pretty sure the GrADS I/O on such a file would be questionable at
>best, since everything begins with the variable name. I suggest you
>ask the data providers for an explanation and forward the answer to
>us. Anyone on the CERES team subscribed to gradsusr?
>Jennifer
>--
>Jennifer Miletta Adams
>IGES/COLA
>4041 Powder Mill Rd., Suite 302
>Calverton, MD 20705
>jma at cola.iges.org
>
>On Jul 1, 2005, at 6:29 PM, Katia Fernandes wrote:
>
>> Hello,
>>
>> I have been trying to read a HDF file into GrADS for about a month
>> with no
>> complete success, so I wonder if one of you would have an idea of
>> what it is
>> I am doing wrong.
>>
>> One noticeable particularity of the data I am dealing with is that it
>> contains more than one variable with the same name, differing in
>> dimensions
>> only, as seen in the example below:
>> (the ncdump (-h) file is 50 pages long, so in case it is needed I
>> can send
>> it in a subsequent email) .
>>
>> ----------------------------------------------------------------------
>> ------
>> netcdf CER_SRBAVG1_TRMM-PFM-VIRS_Edition2B_010018 {dimensions:
>>         1_0_deg__regional_colat__zones = 180 ;
>>         1_0_deg__regional_long__zones = 360 ;
>>         Surface_type = 20 ;
>>         Stats = 3 ;
>>         Monthly_Hourly_Avgs = 24 ;
>>         Monthly_Avg = 1 ;
>>         1_0_deg__zonal_colat__zones = 180 ;
>>         1_0_deg__zonal_long__zones = 1 ;
>>         1_0_deg__global_colat__zones = 1 ;
>>         1_0_deg__global_long__zones = 1 ;
>>
>>
>> variables:
>> float LW_Surface_Emissivity(Monthly_Hourly_Avgs,
>> 1_0_deg__regional_colat__zones, 1_0_deg__regional_long__zones) ;
>>                 LW_Surface_Emissivity:_FillValue = 3.4028235e+038f ;
>>                 LW_Surface_Emissivity:long_name = "1.0 Degree Regional
>> Monthly Hourly Surface Data" ;
>>                 LW_Surface_Emissivity:units = "unitless" ;
>>                 LW_Surface_Emissivity:valid_range = 0.f, 0.f ;
>> .
>> .
>> .
>> float LW_Surface_Emissivity(Monthly_Avg,
>> 1_0_deg__regional_colat__zones,
>> 1_0_deg__regional_long__zones) ;
>>                 LW_Surface_Emissivity:_FillValue = 3.4028235e+038f ;
>>                 LW_Surface_Emissivity:long_name = "1.0 Degree Regional
>> Monthly Surface Data" ;
>>                 LW_Surface_Emissivity:units = "unitless" ;
>>                 LW_Surface_Emissivity:valid_range = 0.f, 0.f ;
>> ----------------------------------------------------------------------
>> -
>> SDFOPEN
>> I am using GrADS 1.9b4. I tried sdfopen and got the message.
>> Scanning self-describing file:  CER_SRBAVG1_TRMM-PFM-
>> VIRS_Edition2B_010018
>> SDF file has no discernable X coordinate.
>>
>> ----------------------------------------------------------------------
>> -------------------------------------------------------------------
>>
>> OPEN
>> So I tried using open with the following .ctl:
>>
>> DSET ^CER_SRBAVG1_TRMM-PFM-VIRS_Edition2B_010018
>> DTYPE hdfsds
>> TITLE CERES-TRMM monthly data
>> UNDEF 3.4028235E38 _FillValue
>> XDEF 360 LINEAR -180 1.0
>> YDEF 180 LINEAR  -90 1.0
>> ZDEF 1  LEVELS 1000
>> TDEF  1 LINEAR 01FEB1998 1mo
>> VARS 1
>> LW_Surface_Emissivity=>lwe 0 y,x Emissivity
>> ENDVARS
>>
>> ga-> open ceres.ctl
>> Scanning description file:  ceres.ctl
>> Data file CER_SRBAVG1_TRMM-PFM-VIRS_Edition2B_010018 is open as file 1
>> LON set to 0 360
>> LAT set to 90 89
>> LEV set to 1000 1000
>> Time values set: 1998:2:1:0 1998:2:1:0
>> ga-> d lwe
>> Error: Variable LW_Surface_Emissivity not in HDF-SDS file
>> Data Request Error:  Error for variable 'lwe'
>>   Error ocurred at column 1
>> DISPLAY error:  Invalid expression
>>   Expression = lwe
>>
>> ----------------------------------------------------------------------
>> -------------------------------------------------------------------
>>
>> XDFOPEN
>>
>> Then I tried xdfopen, so it would give me more flexibility on
>> pointing the
>> variable to its specific time dimension in TDEF, making it “clear”
>> which
>> variable I want. Below is the ddf.
>>
>> DSET ^CER_SRBAVG1_TRMM-PFM-VIRS_Edition2B_010018
>> TITLE CERES-TRMM monthly data
>> UNDEF 3.4028235E38 _FillValue
>> XDEF 1_0_deg__regional_long__zones 360 LINEAR -180.0 1.0
>> YDEF 1_0_deg__regional_colat__zones 180 LINEAR  -90.0 1.0
>> ZDEF Stats 3 LINEAR 1 1
>> TDEF Monthly_Avg 1 LINEAR 01FEB1998 1mo
>> VARS 1
>> LW_Surface_Emissivity=>lwe 0 y,x Emissivity
>> ENDVARS
>>
>> ga-> xdfopen ceres.ddf
>> Scanning Descriptor File:  ceres.ddf
>> XDFOpen Error:  Invalid variable record
>>   --> The invalid description file record is:
>>   --> lw_surface_emissivity=>lwe 0 y,x emissivity
>>   The data file was not opened.
>>
>>
>> I wonder if a specific path for each variable is necessary, since
>> they are
>> named the same. I don’t know how to do that, though.
>>
>> I appreciate any help, suggestions, thoughts on this
.
>>
>> Thanks a lot,
>> Kátia
>>
>>
>
>
>
>



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