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[IDV #HAV-211832]: Fwd: un petit bonjour et petits problÃmes d'usage de donnÃes ECMWF en format NETCDF dans IDV.. .

Salut Gilles,

C'est un peu compliquÃ, malheureusement.

If I understand your problem correctly, this is what you need to do

#1 Define a Jython formula (this formula should hopefully be self-explanatory):

def gilles(geop):
   geoph = geop/9.8
   gh = newUnit(geoph, "z", "m")
   return mag(geo(gh))

To do this go to Field Selector --> Formulas --> Edit Jython library. Define 
this formula in Local Jython --> User's library

#2 Go to Field Selector --> Formulas --> Edit Formulas --> Derived Quantities 
--> Geostrophic Wind

In the Formula editor enter

Formula: gilles(D1)
Description: Gilles Geostrophic Wind (from %N1%)

Press "Change Formula"

Now your new derived formula should be available for display. (You may have to 
restart the IDV here. For some reason, the derived formula did not show up 
immediately for me.)

Try that and let us know if that works.

-Unidata IDV Support

> Putting this into the support queue, so it does not get lost. -Julien
> -------- Original Message --------
> Subject:      un petit bonjour et petits problÃmes d'usage de donnÃes ECMWF
> en format NETCDF dans IDV...
> Date:         Fri, 18 Nov 2011 13:01:44 -0600 (CST)
> From:         Arfeuille <address@hidden>
> To:   Julien Chastang <address@hidden>
> Bonjour Julien,
> J'espÃÂre que tout va bien pour toi,
> Un truc un peu fou que je viens de remarquer et je ne sais comment 
> solutionner le problÃÂme...je suis en train de travailler avec des 
> donnÃÂes de ERA Interim de ECMWF que j'ai pris en format NETCDF pour les 
> comparer dans IDV avec des donnÃÂes rÃÂelles que je mesure sur le terrain 
> ici et avec des donnÃÂes de NCEP reanalysis...
> Je regarde le vent gÃÂostrophique calculÃÂ Ã  partir de ...mince alors 
> là je dois passer à l'anglais...
> So I plot with IDV the geostrophic wind derived from the geopotential of the 
> ECMWF data file I got in NETCDF format and I get crazy values...I dig in the 
> ECMWF website to understand in which units is the geopotential and it is not 
> in meters but in meters square per second square, so to get the geopotential 
> height field I need to divide the geopotential by 9.80665 at each point and 
> that's it...yep, but I get the geopotential height field for a certain 
> pressure level as a value plot on the map, at least I can check the values 
> are realistic but I am stuck because I don't know what to do to get the 
> derived geostrophic wind from that result since it is a plot not a variable 
> known by the software as gopotential height tha I can use to get to view the 
> geostrophic wind field at the specific pressure level, which is really what I 
> need...
> Si tu as une idÃÂe ou plusieurs merci pour ton aide, et si non et bien 
> merci quand mÃÂme pour ÃÂcouter mes lamentations...
> a+
> gilles
> --
> Este mensaje ha sido analizado por MailScanner de
> la Universidad de Colima en busca de virus y otros
> contenidos peligrosos, y se considera que està limpio.

Ticket Details
Ticket ID: HAV-211832
Department: Support IDV
Priority: High
Status: Closed

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