[Met_help] Wind Speed Verification

[John Halley Gotway]

Brent,

Great.  If you're able to generate observation values of U, V, wind speed, and wind direction, that'd be good.  Whether you add wind speed and direction to the GRIB files is up to you.  Like I said,
if they're there, Point-Stat will use them.  If they're not, Point-Stat will do the following:
- Look for U and V at the same vertical level you requested.
- Check if U and V are grid-relative or earth-relative.  If they're grid-relative, it'll rotate them to be earth-relative.
- Derive wind speed from the earth-relative U and V.
- We assume that the observations are earth-relative.

You should be able to run Point-Stat to verify U, V, and wind speed.

I won't pursue modifying ASCII2NC to add the derivation of wind speed.

Just let me know if any more questions come up.

Thanks,
John

Brent L Shaw wrote:
> John,
> 
> OK.  Originally, my program that creates the ASCII files we process through ASCII2NC had wind direction and speed, but then U and V were not getting verified.  I think it may be easy for me to add those back in.  I should probably go ahead and add wind speed and direction to the GRIB files as well.  I am sure we will need those for somebody sometime anyway!
> 
> Brent
> 
> -----Original Message-----
> From: John Halley Gotway [mailto:johnhg at rap.ucar.edu] 
> Sent: Thursday, July 09, 2009 11:14 AM
> To: Brent L Shaw
> Cc: Phillip Spencer; met_help
> Subject: Re: Wind Speed Verification
> 
> Brent,
> 
> I took a look at the data you sent and this time the news isn't as good.
> 
> Point-Stat is deriving a wind speed forecast field from the U and V components.  However, it's not doing so for the point observations.  It's in the PB2NC tool that we have the ability to derive wind
> speed observations from U and V.  But since you're using ASCII2NC, the derivation of wind speed isn't currently available.
> 
> It occurs to me that I may be able to add a few lines of code to add the derivation of wind speed to ASCII2NC.  Let me give it a shot, and I'll get back to you.  The other option would be for you to
> do it when formatting the ASCII obs as input for ASCII2NC.
> 
> Thanks,
> John
> 
> 
> Brent L Shaw wrote:
>> Hi John,
>>
>> I work with Phillip Spencer, and we were trying your suggestion this morning on adding WIND to the configuration file.  When I ran point_stat, it still did not verify the wind speed.  Even though it showed 1800+ pairs for UGRD and VGRD, it showed verifying with 0 pairs when it tried to do WIND.  In our case, we are doing WIND/Z010.  Our GRIB file has grid-relative U and V components, and our observation file has true U and V components.  Note that we do not use WRFPost.  If all else fails, I can create wind direction and speed in our post-processing, but I would prefer not to have to do that if I don't need to.
>>
>> I have attached the GRIB file, the observation file, and the configuration file used for trying to run point_stat.   Your help is appreciated!
>>
>> On a different note, I mentioned these two suggestions to Barb at the WRF Users' Conference a couple of weeks ago, and she said I should pass them along to you:
>>
>>
>>  1.  It would be helpful if the matched pair lines could also include the station ID instead of just the lat/lon.
>>  2.  We would like to use MySQL to store various stats so we can more easily dynamically query for the necessary metrics.  Barb mentioned that such a capability is being worked on, so I would like to pass along our advocacy for that.
>>
>> Best regards,
>>
>> Brent
>>
>> _____________________________
>> Brent L. Shaw
>> V.P., Director of NWP Laboratory
>> Weather Decision Technologies, Inc.
>> Office:    (405) 579-7675 x246
>> Mobile:   (405) 397-9950
>> e-mail:    bshaw at wdtinc.com
>>
>>