[gradsusr] MODIS AEROSOL PRODUCTS

Sagar P Parajuli psagar at utexas.edu
Wed May 29 08:21:11 EDT 2013


Hi Joshua,
It seems that you merged the files correctly using cdo mergetime. There are
other options as well for merging such as cdo copy and cdo cat. To merge
multiple files just use a wild character for file names eg. cdo mergetime
MOD*. It will work. If the merged file doesn't open using sdfopen, then use
xdfopen.


-Sagar


On Wed, May 29, 2013 at 7:08 AM, Joshua Ngaina <jngaina at gmail.com> 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
>
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>
>


-- 

**
Sincerely,

* *

*Sagar P. Parajuli*

**Graduate Research Assistant

The University of Texas at Austin
Jackson School of Geosciences
e-mail: psagar at utexas.edu
Contact: +1 512 965 4093
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