[gradsusr] MODIS AEROSOL PRODUCTS

Thu May 30 05:44:45 EDT 2013

Hi,

Just a follow up, I managed to assign my data time dimension and also merge
them. However, I have four variables which have the same variable name for
the different range.  If i try to display, It GrADS complains: Cannot
contour grid - all undefined values

How do I go about this

ga-> open model.ctl
Scanning description file:  model.ctl
Data file MIL3MAE.%d2.nc is open as file 1
LON set to 0 360
LAT set to -89.75 89.75
LEV set to 1 1
Time values set: 2000:2:1:0 2000:2:1:0
E set to 1 1
ga-> q file
File 1 : "Joshua ngaina Data for GrADS Tutorial"
  Descriptor: model.ctl
  Binary: MIL3MAE.%d2.nc
  Type = Gridded
  Xsize = 720  Ysize = 360  Zsize = 1  Tsize = 6  Esize = 1
  Number of Variables = 4
     optical_depth_a  0  y,x  Optical_depth_average_infrared
     optical_depth_a  0  y,x  Optical_depth_average_Red
     optical_depth_a  0  y,x  Optical_depth_average_Green
     optical_depth_a  0  y,x  Optical_depth_average_Blue

Joshua

On Thu, May 30, 2013 at 5:11 AM, Joshua Ngaina <jngaina at gmail.com> wrote:

> Thanks guys for your response. I took time to try all your suggestions and
> learnt something new in one way or another. Jennifer's suggestions really
> worked in my case.
>
> regards
>
> Joshua
>
>
> On Wed, May 29, 2013 at 7:15 PM, Jennifer Adams <jma at cola.iges.org> wrote:
>
>> If a netcdf file doesn't have a time dimension, GrADS will assign a
>> default time of 00z01jan0001 to the file. That message is not an error, it
>> is a warning -- the file was opened successfully. If you want the default
>> time to be something else, use a simple xdfopen-style descriptor to assign
>> a time. If you want to merge files over the time dimension, you can use
>> templating with the CHSUB option -- mapping each file to its particular
>> time -- the strings in the filenames are not readily interpreted, so the
>> usual date string substitutions won't work.
>>
>> http://iges.org/grads/gadoc/SDFdescriptorfile.html
>> http://iges.org/grads/gadoc/templates.html
>>
>> --Jennifer
>>
>> On May 29, 2013, at 8:08 AM, Joshua Ngaina wrote:
>>
>>
>> *Dear All,
>>
>> *
>> *I have daily MODIS aerosol products (Small mode fraction).
>>
>> *
>> *I wanted to merge these files using CDO but it seemed the files were
>> not merged.  *
>>
>> met at met-HP-Compaq-6000-Pro-MT-PC:/media/BERTH/MODIS_DAILY$ cdo mergetime
>> *.nc ALLMOD08.nc
>> cdo mergetime: Processed 4147200 values from 64 variables over 32
>> timesteps. ( 0.18s )
>> *
>> So to check one of the files, I used grads and I got this error: DF file
>> has no discernable time coordinate -- using default values*.
>>
>> ga-> sdfopen
>> MOD08_D3.A2001001.051.2010286151047.pscs_000500504418.Optical_Depth_Ratio_Small_Land_And_Ocean_Mean.G3.nc
>> Scanning self-describing file:
>> MOD08_D3.A2001001.051.2010286151047.pscs_000500504418.Optical_Depth_Ratio_Small_Land_And_Ocean_Mean.G3.nc
>> SDF file has no discernable time coordinate -- using default values.
>> SDF file
>> MOD08_D3.A2001001.051.2010286151047.pscs_000500504418.Optical_Depth_Ratio_Small_Land_And_Ocean_Mean.G3.ncis open as file 1
>> LON set to 0 360
>> LAT set to -89.5 89.5
>> LEV set to 0 0
>> Time values set: 1:1:1:0 1:1:1:0
>> E set to 1 1
>> ga-> q file
>> File 1 :
>>   Descriptor:
>> MOD08_D3.A2001001.051.2010286151047.pscs_000500504418.Optical_Depth_Ratio_Small_Land_And_Ocean_Mean.G3.nc
>>   Binary:
>> MOD08_D3.A2001001.051.2010286151047.pscs_000500504418.Optical_Depth_Ratio_Small_Land_And_Ocean_Mean.G3.nc
>>   Type = Gridded
>>   Xsize = 360  Ysize = 180  Zsize = 1  Tsize = 1  Esize = 1
>>   Number of Variables = 2
>>      optical_depth_l  0  y,x  Aerosol Optical Thickness at 0.55 microns
>> for both Ocean (best) and Land (corrected): Mean
>>      optical_depth_r  0  y,x  Ratio of small mode aerosol optical depth
>> at 0.55 micron for both land and ocean: Mean
>> *
>> *
>> *I also checked the merged netcdf file *
>>
>> ga-> sdfopen ALLMOD08.nc
>> Scanning self-describing file:  ALLMOD08.nc
>> SDF file has no discernable time coordinate -- using default values.
>> SDF file ALLMOD08.nc is open as file 1
>> LON set to 0 360
>> LAT set to -89.5 89.5
>> LEV set to 0 0
>> Time values set: 1:1:1:0 1:1:1:0
>> E set to 1 1
>> ga-> q file
>> File 1 :
>>   Descriptor: ALLMOD08.nc
>>   Binary: ALLMOD08.nc
>>   Type = Gridded
>>   Xsize = 360  Ysize = 180  Zsize = 1  Tsize = 1  Esize = 1
>>   Number of Variables = 2
>>      optical_depth_l  0  y,x  Aerosol Optical Thickness at 0.55 microns
>> for both Ocean (best) and Land (corrected): Mean
>>      optical_depth_r  0  y,x  Ratio of small mode aerosol optical depth
>> at 0.55 micron for both land and ocean: Mean
>>
>> *I also noted that the dimension of both files were the same.
>>
>> *
>> *My major problem is with many files of this type, How do I merge this
>> files for analysis with GrADs. Please advise
>> *
>> *
>> *
>> *
>> Regards and Thanks,*
>>
>> Joshua Ngaina
>>  _______________________________________________
>> gradsusr mailing list
>> gradsusr at gradsusr.org
>> http://gradsusr.org/mailman/listinfo/gradsusr
>>
>>
>> --
>> 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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