[Met_help] How to specify the surface variable in the point_stat?

[John Halley Gotway]

Kefeng,

Sorry for the delay in getting back with you.

Yes, specifying "TMP/Z0" should tell Point-Stat to retrieve the surface
temperature variable.  If for some reason that doesn't work, try using
"TMP/L0" instead.  The difference is that when you say Z0, Point-Stat
tries to find a GRIB record that's defined as a VERTICAL level with a
level value of 0.  When you say L0, Point-Stat tries to find a GRIB record
with a level value of 0 regardless of what "type" of level it is: vertical
level, pressure level, or any other type of level.  But "TMP/Z0" should do
the trick.

Here's the scoop on matching to vertical levels in Point-Stat...
Point-Stat doesn't even look at the height value for the observation
points.  Instead, the matching for surface variables is done entirely by
message type.  Any observations with a message type of ADPSFC or SFCSHP
are considered to be at the surface and are matched to surface variables. 
So if you're verifying TMP/Z0, you should verify using observations with a
message type of ADPSFC or SFCSHP.

For this reason, in METv2.0 you won't be able to match MSONET observations
to surface variables because the code doesn't consider the MSONET message
type to be at the surface.

I realize that this logic for matching in the veritical is rather
simplistic.  We inherited it from some exisitng NCEP verification code,
and decided not to alter it until it becomes necessary to do so.

If this doesn't meet your needs, let me know.  And we can look for more
sophsticated ways of matching in the vertical.  If that is needed, it'd be
helpful for you to send us a sample forecast file, sample point
observation file, and a description of how exactly you'd like them to be
matched up in the vertical.

I'll be out of town all next week at a conference, so I won't have much
time to respond until the following week.

Thanks,
John Halley Gotway
johnhg at ucar.edu

>
> Hi:
>
>     I'm wondering how to specify the surface variable like surface
> temperature? Does 'TMP/Z0' work? How does MET deal with the
> observation when i specify 'TMP/Z0' while actually the observed
> temperature are at 1.5m height?
>      Another question is do MET have any detail instruction about what
> kind of variable can be verified by specified type of observation
> like MSONET?  Beacuse when i set the
> fcst_field[] = [ "TMP/Z0", "UGRD/Z10", "VGRD/Z10" ];
> message_type[] = [ "MSONET" ];
>     I got nothing after the point_stat analysis.
>     Thanks!
>
> Kefeng
>
> 2009-05-27
>
>
>
> Zhu,Kefeng
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