[gradsusr] merra data

Tue Oct 4 12:25:49 EDT 2011

Hi,

Thank you a lot; it is working with Template and xdfopen; for wind 
energy, we are working on ~ 10 years of data.

just a small problem: for 3 months (june to august;, 2010), Merra data 
have another name; that must be another run, i think.
Best regards.
Antoine

Le 04/10/2011 15:49, Arlindo da Silva a écrit :
> On Tue, Oct 4, 2011 at 6:50 AM, Molin Antoine <antoine.molin at poweo.com 
> <mailto: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 
> <http://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 <mailto: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 <mailto:dasilva at alum.mit.edu>
>
>
>     -- 
>
>     -- 
>
>     *Antoine Molin*
>
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>
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>
>
> -- 
> Arlindo da Silva
> dasilva at alum.mit.edu <mailto:dasilva at alum.mit.edu>

-- 

-- 

*Antoine Molin*

**

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