On Fri, Sep 30, 2011 at 4:22 AM, Molin Antoine <span dir="ltr"><<a href="mailto:antoine.molin@poweo.com">antoine.molin@poweo.com</a>></span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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<div>Dear All,<br>
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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
<a>file:hourly</a> wind speeds at 50m for one day, NetCDF).<br>
But then?<br>
Could you tell me how you would:<br>
* aggregate the daily files: do you use "template"<br></div></div></blockquote><div><br></div><div>Yes.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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* 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?).<br></div></div></blockquote><div><br></div><div>Using a template makes it easier to work with the HDF files.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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* best way to eventually create the descriptor file<br></div></div></blockquote><div><br></div><div>Yes, it should be sufficient to create a DDF file with 3 records: DSET, OPTIONS template, and TDEF. Please read the User's Guide:</div>
<div><br></div><div> <a href="http://grads.iges.org/grads/gadoc/SDFdescriptorfile.html">http://grads.iges.org/grads/gadoc/SDFdescriptorfile.html</a></div><div><br></div><div>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: <a href="http://cookbooks.opengrads.org/index.php?title=Table_of_Contents#NASA.2FGSFC_MERRA">2.6.1 NASA/GSFC MERRA</a></div>
<div><br></div><div>The opengrads bundle also ships with a GUI interface for browsing the MERRA datasets, see</div><div><br></div><div> <a href="http://cookbooks.opengrads.org/index.php?title=Recipe-016:_Accessing_MERRA_data_with_a_Graphical_User_Interface">http://cookbooks.opengrads.org/index.php?title=Recipe-016:_Accessing_MERRA_data_with_a_Graphical_User_Interface</a></div>
<div><br></div><div>Just type "merra" on the command line; under Windows you should have a MERRA icon on your desktop.</div><div><br></div><div> Arlindo</div><div><br></div><div><br></div><div><br></div><div>
<br></div><div><br></div></div>-- <br>Arlindo da Silva<br><a href="mailto:dasilva@alum.mit.edu">dasilva@alum.mit.edu</a><br>