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[GEMPAK #ULU-782715]: how to get wind component
- Subject: [GEMPAK #ULU-782715]: how to get wind component
- Date: Tue, 18 Aug 2009 11:35:37 -0600
To answer your first question, you can simply use SFPARM = UWND;VWND (for wind
in meters/second) or SFPARM = UKNT;VKNT (for knots) in the SF programs to find
the U and V components of the wind, provided your surface file has the wind
speed and direction parameters.
See the SFPARM man page for more information:
http://www.unidata.ucar.edu/cgi-bin/gempak/manual/variables_index?sfparm
As for your second question, you can check if UWND and VWND are in your grid
files with the program GDINFO
http://www.unidata.ucar.edu/cgi-bin/gempak/manual/programs_index?gdinfo
Finally, UREL and VREL are in meters per second, as defined in the grib product
they are decoded from, using table $GEMTBL/grid/wmogrib2.tbl. This table
defines the parameter names, units and scaling for the grib parameter id from
the model output.
To output in knots, you can use KNTV(UREL) and KNTV(VREL)
-Michael
> dear sir:
>
> I'm very thanks for your advice to help me solve the problem creating
> correct surface file . however there 3 questions to want you help.
>
> First question, I want to get the wind components u and v by wind
> dircetory and speed.could you told me what should I do ?
>
> sceond question ,are both uwnd and vwnd in the grd files if I want to
> draw a streamline by gdstream program?
>
> finally, could you told me the difference between uwnd and urel?
>
> thanks
>
> 2009-08-17
>
>
>
> gcs
>
>
Ticket Details
===================
Ticket ID: ULU-782715
Department: Support GEMPAK
Priority: Normal
Status: Open