[Met_help] [rt.rap.ucar.edu #50812] History for Question on ME statistic (UNCLASSIFIED)

Tressa Fowler via RT met_help at ucar.edu
Wed Oct 19 13:19:42 MDT 2011

  Initial Request

Classification: UNCLASSIFIED
Caveats: NONE

I used Point-Stat to compute the ME for 10 meter wind speed (WIND) and 10
meter U and V component wind speeds (UGRD, VGRD) from ADPSFC observations
and WRF forecasts. 

The values (aggregated over 9 forecast valid times per day for 31 days) for
ME for WIND was -0.22  and the ME for U was 0.33 and for V was 0.41. 

Is it consistent for the WIND to be underforecast while the components winds
are overforecast from a statistical sense?



Mr John W. Raby, Meteorologist
U.S. Army Research Laboratory
White Sands Missile Range, NM 88002
(575) 678-2004 DSN 258-2004
FAX (575) 678-1230 DSN 258-1230
Email: john.w.raby2.civ at mail.mil

Classification: UNCLASSIFIED
Caveats: NONE

  Complete Ticket History

Subject: Question on ME statistic (UNCLASSIFIED)
From: Tressa Fowler
Time: Wed Oct 19 10:55:00 2011

Hi John,

This is entirely possible. I think the bias of the wind speed is more
informative than the bias in the u and v components. The u and v
components can be negative and they contain information about the
direction of the wind. The wind speed has no information about the
direction and is just the length of the vector. It may be that your u
and v biases are telling you about systematic wind direction errors,
which can be positive and may have nothing to do with whether the wind
speed is correct.

Make sense?



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