[gradsusr] merra data

Tue Oct 4 09:49:00 EDT 2011

On Tue, Oct 4, 2011 at 6:50 AM, Molin Antoine <antoine.molin at poweo.com>wrote:

> **
> Hi,
>
> Thanks for your answer.
>
> I tasted your cooking, and it is good; but we would like to get the MERRA
> data at the resolution 2/3 ° x 0.5°.
>
>
For the record, this should not make a difference. Here is the lats4d syntax
to bring about a week of data with these:

% lats4d.sh -i http://goldsmr2.sci.gsfc.nasa.gov:80/dods/MAT1NXSLV -vars slp
u50m v50m t2m -time 0:30z01jan2001 23:30z07jan2001 -o merra_slv -v

(Notice that I used lower case "slp".) Go get a cup of coffee and when you
come back this will create a netcdf file called "merra_slv.nc"; use the
-format option to choose another format.

> So i downloaded the Merra data, hdf files, with the variables SLP, U50m,
> V50m and T2m.
>
> * the variable SLP is not recognized by Grads!
>

The attached file does not have SLP. Please file a bug report with the
M-DISC.

> (the variable "SLP" is on the Merra site:
> http://disc.sci.gsfc.nasa.gov/daac-bin/FTPSubset.pl?LOOKUPID_List=MAT1NXSLV
> )
>
> * i tried first to read a hdf file with xdfopen, but the written ddf
> (enclosed file) is not good; a "SDF_dimension_name" is lacking, i think, for
> TDEF; but how do you name this dimension_name? and how do you scan a hdf
> file?
>
>
Did you create this ctl file or it came with the data? The attached ctl is
wrong as it mixes elements of DDF and CTL.  Here is a templates DDF (I did
not try it):

dset ^MERRA.%y4%m2%d2.SUB.hdf
options template
tdef time 24 linear 00:30Z01jan2001 1hr

If you need a relatively short period of time, why mess with this? Just use
lats4d as above and save yourself some work.

    Arlindo

> Thanks, and best regards.
> Antoine Molin
>
>
>
>
>
> Le 30/09/2011 22:17, Arlindo da Silva a écrit :
>
> On Fri, Sep 30, 2011 at 4:22 AM, Molin Antoine <antoine.molin at poweo.com>wrote:
>
>>
>> Dear All,
>>
>> For wind energy in France, i would like to use Merra data; it is in fact
>> rather easy to get daily files from the Nasa (enclosed file:hourly wind
>> speeds at 50m for one day, NetCDF).
>> But then?
>> Could you tell me how you would:
>> * aggregate the daily files: do you use "template"
>>
>
>  Yes.
>
>
>>  * read the aggregate files (i think we need a descriptor file and use
>> xdfopen or open under grads, isn'it?; or is it better to work with HDF
>> files?).
>>
>
>  Using a template makes it easier to work with the HDF files.
>
>
>>  * best way to eventually create the descriptor file
>>
>
>  Yes, it should be sufficient to create a DDF file with 3 records: DSET,
> OPTIONS template, and TDEF. Please read the User's Guide:
>
>             http://grads.iges.org/grads/gadoc/SDFdescriptorfile.html
>
>  Now, depending on the extent of data analysis you need to perform it may
> be practical for use to access MERRA data directly through OPeNDAP. In fact,
> we have made the whole MERRA collection on-line. There are a number of
> recipes in the Cookbook explaining how to work with MERRA data, click on
> this link: 2.6.1 NASA/GSFC MERRA<http://cookbooks.opengrads.org/index.php?title=Table_of_Contents#NASA.2FGSFC_MERRA>
>
>  The opengrads bundle also ships with a GUI interface for browsing the
> MERRA datasets, see
>
>
> http://cookbooks.opengrads.org/index.php?title=Recipe-016:_Accessing_MERRA_data_with_a_Graphical_User_Interface
>
>  Just type "merra" on the command line; under Windows you should have a
> MERRA icon on your desktop.
>
>      Arlindo
>
>
>
>
>
>  --
> Arlindo da Silva
> dasilva at alum.mit.edu
>
>
>
> --
>
> --
>
> *Antoine Molin*
>
> **
>
> ****
>
> [image: EED POWEO Logo]
>
> 16, Place Cormontaigne - 59000 Lille****
>
> ****
>
> Tel. : *+ 33 3 20 74 04 00*
>
> Fax : + 33 3 20 74 04 07****
>
> *poweo.com <http://www.poweo.com/>*
>
> **
>
> Avant d'imprimer, pensez à l'environnement****
>
> _______________________________________________
> gradsusr mailing list
> gradsusr at gradsusr.org
> http://gradsusr.org/mailman/listinfo/gradsusr
>
>

-- 
Arlindo da Silva
dasilva at alum.mit.edu
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20111004/7e02c082/attachment-0003.html 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 14564 bytes
Desc: not available
Url : http://gradsusr.org/pipermail/gradsusr/attachments/20111004/7e02c082/attachment-0003.jpe 