[gradsusr] opening modis hdf files

[Sergey Varlamov]

Dear Sagar P Parajuli,

It is normal grads behavior: GrADS cuts names of variables to 15 symbols.
To overcome it, you have to add also the variables description section to
your description file and assign short "GrADS names" that you like
to original long names in the HDF file, like:

dset ^./MYD08_D3.A2003121.005.2007081003101.hdf
xdef XDim:mod08 360 linear -180.0 1.0
ydef YDim:mod08 180 linear -90.0 1.0
vars 3
Deep_Blue_Aerosol_Optical_Depth_550_Land_Mean=>od_550 0 y,x Optical
depth at 0.55 microns for land (corrected): Mean
Deep_Blue_Aerosol_Optical_Depth_550_Land_Standard_Deviation=>od_550_sd 0
y,x Optical depth at 0.55 microns for land (corrected): Standard Deviation
Deep_Blue_Aerosol_Optical_Depth_550_Land_Minimum=>od_550_min 0 y,x
Optical depth at 0.55 microns for land (corrected): Minimum
endvars

Inside must be just "vars" lines, 3 in the example above.
If you have other - please add description lines and modify
vars number.
See the Grads documentation for details and modify example above,
especially if you receive again some strange images.
Description of variables has to consistent with the hdf structure:
number of vertical levels if any (0 above),  grid layout etc.

Hope it could help you.

Sergey Varlamov


Sagar P Parajuli wrote:
> Hi,
> I was able to open modis hdf file (MYD08_D3) using xdfopen with following
> script:
> dset ^./MYD08_D3.A2003121.005.2007081003101.hdf
> xdef XDim:mod08 360 linear -180.0 1.0
> ydef YDim:mod08 180 linear -90.0 1.0
> However, when I see the variables using ctlinfo, it shows more than one
> variables with the same variable name. For example, in the below lines, all
> three variables have same variable name deep_blue_aeros.
>
> Deep_Blue_Aerosol_Optical_Depth_550_Land_Mean=>deep_blue_aeros  0  y,x
> Deep blue aerosol optical depth at 0.55 microns for land (corrected): Mean
> Deep_Blue_Aerosol_Optical_Depth_550_Land_Standard_Deviation=>deep_blue_aeros
> 0  y,x  Deep blue aerosol optical depth at 0.55 microns for land
> (corrected): Standard Deviation
> Deep_Blue_Aerosol_Optical_Depth_550_Land_Minimum=>deep_blue_aeros  0  y,x
> Deep blue aerosol optical depth at 0.55 microns for land (corrected):
> Minimum
>
> When I display the variable using d deep_blue_aeros, it doesn't show
> realistic image. I don't know which variable out of three is being
> displayed. Could anyone help on this?
>
>   
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-- 

Sergey Varlamov

Research Institute for Global Change
JAMSTEC, JAPAN