.ctl for MODIS HDF file

[Jennifer Adams]

What is the output from 'q config' ?

On Oct 19, 2009, at 3:49 PM, Hao He wrote:

> I put this in my .ctl file as an example:
>
> set ^MOD06_L2.A2008094.0225.005.2008096042152.hdf
> title MODIS Level 2 cloud product
> undef -32768
> xdef 270 linear 112.856 0.1201260
> ydef 406 linear 29.1195 0.0525835
> tdef 1 linear 02:25Z03APR2008 5MN
> zdef 1 linear 1 1
> dtype hdfsds
> vars 3
> Latitude=>scanlat 0 y,x Geodetic Latitude
> Longitude=>scanlon 0 y,x Geodetic Longitude
> Surface_Pressure=>sfcpres 0 y,x Surface Pressure
> endvars
>
> But I got this warning:
>
> Scanning description file:
> MOD06_L2.A2008094.0225.005.2008096042152.ctl
> Open Error:  Data file type invalid
>  --> The invalid description file record is:
>  --> dtype hdfsds
>
> I am confused about the data type. Not HDF-SDS?
>
> Hao
>
> |  Hao He                                       |
> |  Graduate Assistant                           |
> |  CSS bldg 4365                                |
> |  Jull Hall lab (301)405-7625                  |
> |  Cellphone     (240)672-7912                  |
> |  Department of Atmospheric & Oceanic Science  |
> |  University of Maryland                       |
> |  College Park, MD 20742                       |
>
> On Mon, 19 Oct 2009, Jennifer Adams wrote:
>
>> I can't allow misinformation to go out to the list uncorrected: GrADS
>> can read any HDF file containing gridded fields.
>> This particular HDF file contains swath data. It's gridded -- there
>> are 406 cells in the along-swath direction, and 270 cells in the
>> across-swath direction. GrADS will read this data, but only onto an
>> abstract x,y grid. The lat/lon values of each grid point are read in
>> as data variables. A full 'dtype hdfsds' descriptor file would
>> include
>> the following lines:
>>
>> xdef 270 linear 1 1
>> ydef 406 linear 1 1
>> tdef 1 linear ...
>> ...
>> vars 4
>> Latitude=>scanlat 0  y,x  Geodetic Latitude
>> Longitude=>scanlon 0 y,x Geodetic Longitude
>> Scan_Start_Time=>scantime 0 y,x International Atomic Time at Start of
>> Scan replicated across the Swath
>> Surface_Temperature=>tsfc 0 y,x Surface_Temperature
>> endvars
>>
>> You can add more variables, including some that have a Z axis,
>> depending on what you'd like to look at in the file. The rest of the
>> required descriptor file entries are discussed in the documentation
>> page http://iges.org/grads/gadoc/SDFdescriptorfile.html
>>
>> --Jennifer
>>
>>
>> On Oct 19, 2009, at 10:49 AM, Yan Libin wrote:
>>> a ctl is not enough
>>
>> On Oct 19, 2009, at 10:49 AM, Jayakrishnan PR wrote:
>>> ... we cannot open them through grads by writing a ctl file.
>>
>>
>> On Oct 19, 2009, at 10:26 AM, Hao He wrote:
>>
>>> Hi,
>>> I want to read MODIS HDF file by GrADS. Unfortunately both sdfopen
>>> and
>>> xdfopen do not work for me, so I need to write a complete .ctl file.
>>> But
>>
>>> I am confused after reading the MODIS data set
>>> (http://modis-atmos.gsfc.nasa.gov/MOD07_L2/format.html)
>>
>>> I am wondering if anyone has experience on it.
>>> Thanks a lot!
>>>
>>> Hao

--
Jennifer M. Adams
IGES/COLA
4041 Powder Mill Road, Suite 302
Calverton, MD 20705
jma at cola.iges.org



-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20091019/fed4be01/attachment.html