[Met_help] Wind analysis

[John Halley Gotway]

Joe,

No, L10 is fine.  The Z10 vs L10 is a pretty subtle difference.  Each GRIB records has a level value and level type associated with it.  If you put "WIND/Z10", MET will search through the GRIB records
and only select those that have a level "type" of being a "vertical level", i.e. meters above ground.  If you put "WIND/L10", it'll grab the first GRIB record that has a level value of 10, regardless
of the level type.  So it really should have no impact unless you're using a GRIB record with a "weird" level type.

John

Joe Eastman wrote:
> Hi John,
> 
> We followed this line of thinking and Todd has this working. For 10m winds, he used the L10. It seemed to work. Should we have used Z10 though?
> 
> Take care,
> Joe
> 
> Dr. Joseph L. Eastman
> Senior Atmospheric Scientist 
> WindLogics Inc.
> 201 4th St NW
> Grand Rapids, MN
> 55744
> 
> c - 410.279.9702
> w - 651.556.4297
> jeastman at windlogics.com
> 
> 
> 
> -----Original Message-----
> From: John Halley Gotway [mailto:johnhg at ucar.edu] 
> Sent: Thursday, May 13, 2010 10:07 AM
> To: Joe Eastman
> Cc: Todd Harris; met_help at ucar.edu
> Subject: Re: [Met_help] Wind analysis
> 
> Joe,
> 
> I wanted to follow up with you on this.  I spoke with Tressa Fowler, the scientist leading the MET development effort, and she informed me that it would not be advisable to add the functionality I
> suggested to the STAT-Analysis tool - to extract errors in the wind speed from the VL1L2 lines.  While it's certainly possible to do mathematically, it would be much better to just evaluate the wind
> speed field as we evaluate other scalar fields.  If we were to use the VL1L2 lines instead, all we have is a single measure of wind speed aggregated over the entire verification region.  And there's a
> lot of canceling that would occur.
> 
> My suggestion would be to add WIND (for wind speed) to your Point-Stat configuration file.  Additionally, you could turn on the output of the matched pairs (MPR) line type.  Since you're looking at
> individual stations, those MPR lines shouldn't be too much data.  Then you can run any number of jobs in the STAT-Analysis tool that read those MPR lines for the wind speed from multiple output times
> and compute a variety of different statistics.
> 
> If you have any further scientific questions, I'll refer you to Tressa, tressa at ucar.edu.
> 
> Hope that helps.
> 
> John
> 
> John Halley Gotway wrote:
>> Joe,
>>
>> MET treats wind speed as a scalar field just like any other continuous field.  When you request that wind speed be verified (e.g. fcst_field = "WIND/Z2"; for 2-meter wind speed), MET looks in the
>> input forecast file for wind speed.  If wind speed does not exist in the file, it instead retrieves the corresponding U and V components at that same level and derives wind speed for you.
>>
>> I'm not entirely clear on exactly how you're using MET, so I can't say for sure how best to add wind speed into your analysis.  One option would be to add wind speed to the list of "fcst_fields" being
>> verified in Point-Stat.  However, you'll need to make sure that you have wind speed observations available for verifying the forecasts.
>>
>> But if you're wondering if Stat-Analysis can process VL1L2 lines and dump out stats about errors in wind speed, the answer is no.  It's not currently set up to do that.  However, that certainly does
>> seem a very logical and straight-forward extension of the functionality.  Would you like to see that type of functionality added to the Stat-Analysis tool, read in VL1L2 lines and dump out statistics
>> about errors in wind speed similar to how we handle wind direction?
>>
>> Thanks,
>> John
>>
>>
>> Joe Eastman wrote:
>>> Hello,
>>>
>>> I am in the process of analyzing winds for integrations at several thousand surface stations. I had been using point stat to create the matched pairs and then used statanalysis to do the V1L1 analysis on the wind direction. This is fine for direction but we have no information for wind speed, which in our line of work is the most crucial. Operating on just UGRD or VGRID by themselves is pretty useless. I did not see in the WPP wrf_parm.ctl and option to spit out wind speed. Is there some simple solution to this? Thanks.
>>>
>>> Take care,
>>> Joe
>>>
>>> Dr. Joseph L. Eastman
>>> Senior Atmospheric Scientist
>>> WindLogics Inc.
>>> 201 4th St NW
>>> Grand Rapids, MN
>>> 55744
>>>
>>> c - 410.279.9702
>>> w - 651.556.4297
>>> jeastman at windlogics.com<mailto:jeastman at windlogics.com>
>>>
>>>
>>>
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