[gradsusr] merra data

[Arlindo da Silva]

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
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