[Met_help] stat_analysis VGRD question (UNCLASSIFIED)

John Halley Gotway johnhg at rap.ucar.edu
Tue Apr 21 08:12:01 MDT 2009


Well we've found the first official bug for METv2.0.  It's in Point-Stat, and it's a pretty simple one-line fix.  In the "point_stat.cc" file, where we intend to set the "obs_var" output column, we
are instead setting the "fcst_lev" output column.  The comments in the code say to do the correct thing, but for some reason the code isn't actually doing what the comments say!  I checked in
Grid-Stat in the same spot, but the bug isn't in there.

This bug doesn't affect any of the data values in your output.  It's really just a book-keeping issue in the "obs_var" header column.  In your case the "obs_var" column and the "fcst_var" column
should always contain the same values.  So I'd suggest filtering using the "fcst_var" column and ignore the contents of the "obs_var" column.

I've attached an updated version of the file "METv2.0/src/point_stat.cc" for you to use.  Please do a "make clean" before rebuilding MET.

This fix should make all this UGRD/VGRD/UGRD_VGRD business much less confusing.  Here's a description of how MET handles the U and V components of wind...

The UGRD and VGRD fields are typically treated as separate scalar fields - like any other scalar field such as temperature.  When verifying UGRD, the "fcst_var" and "obs_var" columns should both
contains "UGRD".  When verifying VGRD, the "fcst_var" and "obs_var" columns should both contains "VGRD".  In the case where you list UGRD followed by VGRD at the same vertical level in the config file
(for example, UGRD/P500, VGRD/P500), we interpret that to mean that you'd like to handle the winds as vectors.  So we compute a VL1L2 line which combines the UGRD and VGRD values into vector partial
sums.  In the VL1L2 (and VAL1L2) lines, the "fcst_var" and "obs_var" columns should be set to "UGRD_VGRD" since its a combination of those two fields.  The "UGRD_VGRD" string should ONLY appear in the
VL1L2 lines, and nowhere else in the STAT output.

Thanks for finding this issue.


Sauter, Barbara (Civ, ARL/CISD) wrote:
> Classification:  UNCLASSIFIED 
> Caveats: NONE
> Great.  Thank you.
> Barb
> Classification:  UNCLASSIFIED 
> Caveats: NONE
-------------- next part --------------
A non-text attachment was scrubbed...
Name: point_stat.cc
Type: text/x-c++src
Size: 60563 bytes
Desc: not available
Url : http://mailman.ucar.edu/pipermail/met_help/attachments/20090421/dbe36e18/attachment-0001.bin 

More information about the Met_help mailing list