[Met_help] getting MET stats for wind speed

[John Halley Gotway]

Brain,

Good question... and a rather timely one.

The answer is no.  There is currently no way of verifying wind speed and direction with MET.

However, I'm working to include support for verification of some derived quantities in the next release of MET at the end of the month.

The WRF postprocessor doesn't currently dump out wind speed and direction - just U and V.  We're hoping to add capability for grid_stat and point_stat to derive wind speed and direction from U and V.
 Also, we'll add that derivation in pb2nc to derive wind speed and direction for the observations.  From a user perspective, you should just need to modify your config files to indicate that you'd
like to verify wind speed and direction.

Let me mention an issue regarding winds that's come up in the last couple of days.  Apparently, the WRF postprocessor is dumping out winds that are defined relative to the grid.  The point
observations in the prepbufr files contain winds that are earth relative.  Currently, MET is not accounting for this difference.  Within the DTC we're discussing how to address this - likely through
changes to the postprocessor or changes to MET.

Does that help?

John

Brian Gaudet wrote:
> 
> 
> Hello,
> 
> 
> I have been using the Beta version of METv0.9 to verify WRF-ARW model runs
> (after having been processed by the WRF postprocessor and put into
> GRIB format) against PrepBufr obs.  The tool I've been using
> is point_stat.
> 
> I was wondering if there was a way to verify wind speed and direction 
> using MET if U and V are provided by the model.
> 
> I have put these variables in succession in the .Config file to get
> vector statistics, as recommended by the online Users Guide.
> I do indeed get VL1L2  files, as described in the Users Guide.
> 
> However, I noticed that the parameter provided in the VL1L2
> file is 'Mean(uf ** 2 + vf**2)'.  What I want is 'Mean( (uf ** 2 + vf ** 2) **
> 0.5)',
> and I don't believe these parameters are derivable from each other
> (or any other parameters provided).  Is there another way to
> get this parameter?
> 
> 
> The only way I know of that should work is to output WIND and
> WDIR from the WRF postprocessor; then these fields can
> be verified directly using MET.  However, to do this would
> require some code changes to the WRF postprocessor.
> 
> 
> Thanks for any help you can provide.
> 
> 
> 
> Brian Gaudet
> bjg20 at psu.edu
> 
> 
> 
> 
> 
> 
> 
> 
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