[Met_help] question

[John Halley Gotway]

Holly,

Right now you are using the Point-Stat tool to compare a gridded forecast to point observations.  Point-Stat is the only statistics tool in MET that handles point observations.  The MODE tools
(Grid-Stat and Wavelet-Stat too) can only be run to compare two gridded fields - typically a gridded forecast vs gridded observation or analysis field.

MET won't be able to help you generate a plot of the FCST - OBS values.  If I were in your position, I'd probably do something like the following:

(1) Run my data through Point-Stat and turn on the MPR (matched pair) output line in the Point-Stat configuration file.  This dumps out 1 line of ASCII output for each FCST - OBS matched pair value
that MET computed.

(2) Choose a plotting tool.  I'd probably use NCL (NCAR Command Language) or R (www.r-project.org).  But others, like IDL, may work too.

(3) Use that plotting tool to read the MPR output of Point-Stat.  Each MPR line contains lat/lon info.  So I'd process each line, use the lat/lon value to place it on a plot, and then plot the
difference value.

Hope that helps.

John

Holly Hassenzahl wrote:
> Hi John-
> 
> Happy Tuesday!  Couple quick questions for you:  We would like to create
> a graphical representation of the difference between the forecast and
> actual max and min temps.  Is there a way to do this using the MODE
> tool?  I assume we would have to run both files through PCP Combine
> first?  And if so, how exactly would we do that since we're dealing with
> temps and not precip?
> 
> Thanks,
> Holly
>   
> 
> ___________________________
> Holly C. Hassenzahl
> Meteorologist, Science Analyst
> Weather Central, LLC
> 401 Charmany Drive, Ste 200
> Madison, WI 53719
> (608) 274-5789
> (608) 276-4613 Fax
> www.wxc.com
>  
> -----Original Message-----
> From: John Halley Gotway [mailto:johnhg at ucar.edu] 
> Sent: Wednesday, October 28, 2009 2:50 PM
> To: Holly Hassenzahl
> Cc: met_help
> Subject: Re: question
> 
> Holly,
> 
> OK, I see the problem.  The projection information is not correct in the
> forecast NetCDF file: fcst18z_06L_TMAX.nc
> 
>                 :Projection = "Lambert Conformal" ;
>                 :p1_deg = "39.000000 degrees_north" ;
>                 :p2_deg = "39.000000 degrees_north" ;
>                 :p0_deg = "19.753263 degrees_north" ;
>                 :l0_deg = "168.092865 degrees_east" ;
>                 :lcen_deg = "-98.000000 degrees_east" ;
>                 :d_km = "12.000000 km" ;
>                 :r_km = "6371.200195 km" ;
>                 :ny = "299 grid_points" ;
>                 :nx = "447 grid_points" ;
> 
> I ran this file through the MODE tool, and I just compared it to itself:
> mode fcst18z_06L_TMAX.nc fcst18z_06L_TMAX.nc WrfModeConfig
> 
> And then I looked at the PostScript file that was generated.  The data
> sure looks like it's supposed to be over the CONUS, but the MODE
> PostScript file shows it plotted somewhere else.  That's why
> you're not getting any matched pairs - Point-Stat thinks that your
> domain isn't over CONUS.  Take a look at the attached PNG file to see
> where MODE plots it.
> 
> I thought maybe that l0_deg = "168.092865 degrees_east" was supposed to
> be "-168.092865 degrees_east" but that didn't do the trick.
> 
> Do you have some numbers that define what the projection is supposed to
> be?
> 
> John
> 
> Holly Hassenzahl wrote:
>> Hello John-
>>
>>  
>>
>> I hope this email finds you well!  
>>
>>  
>>
>> I am having another problem with point stat not finding matched pairs.
>> I have uploaded my files to the ftp site and would love some feed back
>> whenever you get a chance.  The files are:
>>
>>  
>>
>> PointStatConfig_max12km
>>
>> obs_17z.nc
>>
>> fcst18z_06L_TMAX.nc
>>
>>  
>>
>> This was working a couple weeks ago, and is working correctly with a
>> forecast file from a different model and valid for the same time.  I
>> viewed both netcdf files and from what I can see, the valid times for
>> TMAX match up correctly.  If there's something you see, please let me
>> know.
>>
>>  
>>
>> Thank you!
>>
>> Holly
>>
>>  
>>
>> ___________________________
>>
>> Holly C. Hassenzahl
>>
>> Meteorologist, Science Analyst
>>
>> Weather Central, LLC
>>
>> 401 Charmany Drive, Ste 200
>>
>> Madison, WI 53719
>>
>> (608) 274-5789
>>
>> (608) 276-4613 Fax
>>
>> www.wxc.com
>>
>>  
>>
>>  
>>
>>