[Met_help] point_stat config question

Fri Aug 21 13:33:25 MDT 2009

John,
I looked at CTC table and thresholds are applied.  However I could not see
thresholds in CNT table. I guess thresholds should be also applied in CNT to
get user desired statistic values (for example bias, rmse), right?

Thanks,
Ruifang

On Fri, Aug 21, 2009 at 8:06 AM, John Halley Gotway <johnhg at rap.ucar.edu>wrote:

> Ruifang,
>
> The behavior you're seeing is correct.  The MPR output would be the same.
>  However, the values in the contingency tables (CTC line type, for example)
> should be different when choosing different
> thresholds.
>
> Here's what's going on...  When you run Point-Stat, you can think of it as
> setting up a bucket for each combination of forecast field/masking
> region/interpolation method.  So for example, suppose you
> configure Point-Stat to verify 2-meter temperature and 500mb temperature
> over 3 masking regions, your FULL domain and then two subdomains.  And
> you're using the nearest neighbor interpolation method.
>  In this case, we'd be verifying 2 fields over 3 regions using 1
> interpolation method.  So Point-Stat will set up 6 "buckets", 3 for 2-meter
> temp and 3 for 500mb temp.
>
> Next, Point-Stat looks at each one of the point observation values you've
> passed to it.  If the observation type (i.e. 2-m temp) matches the forecast
> type, and it's in the correct masking region,
> it'll interpolate the forecast values to the observation location to create
> a matched pair.  Then it throws that matched fcst-obs pair into the
> appropriate bucket.  Point-Stat processes through all of
> the point observations in this way, computing matched pairs, and throwing
> them in the right buckets.
>
> After that's finished, it'll compute whatever statistics you've requested
> using whatever threshold values you've set.  For example, if you set
> threshold values of ">273.0" and ">283.0" for 2-m temp,
> it'll apply those to all of the matched pairs in the "bucket" and compute
> contingency tables and stats.  However, the choice of threshold has no
> effect on which matched pairs make it into the bucket
> to begin with.
>
> The matched pair (MPR) output consists of all the matched pairs that are in
> the buckets.  So the MPR output does NOT depend on any choice of threshold
> value.
>
> Does that make sense?
>
> Thanks,
> John
>
> Ruifang Li wrote:
> > Hi John,
> > I run point_stat tool and did two test with different fcst_thresh[] in
> > config file. I expect the different MPR output, but they create same MPR.
> I
> > could not figure out why. In my understanding, if fcst_thresh eq 0, fcst
> > value in MPR should be 0. if  fcst_thresh le 100 fcst value in MPR should
> be
> > le 100, right?
> >
> > Here are two fcst_thresh:
> >
> > fcst_field[] =
> >
> ["UGRD/Z10","UGRD/P1000","UGRD/P925","UGRD/P850","UGRD/P700","UGRD/P500","UGRD/P400","UGRD/P300","UGRD/P250","UGRD/P200","UGRD/P150","UGRD/P100","UGRD/P70","UGRD/P50","UGRD/P30","UGRD/P20","UGRD/P10"
> > ];
> >
> > //fcst_thresh[] = [ "le100",
> >
> "le10","le10","le100","le100","le100","le100","le100","le100","le100","le100","le100",
> > "le100","le100", "le100","le100","le100" ];
> > fcst_thresh[] = [ "eq0",
> > "eq0","eq0","eq0","eq0","eq0","eq0","le10","eq0","eq0","eq0","eq0",
> > "eq0","eq0", "eq0","eq0","eq0" ];
> >
> > Here is MPR file:
> >
> > /ptmp/lir/test/2009_t8_15km/verify_met2.0/test% ls -l
> > /ptmp/lir/data/2009_t8_15km/verify_met/gsi/point_stat/UGRD/2007081512/
> > total 14208
> > -rw-r--r--    1 lir      ncar         786984 Aug 20 16:05
> > point_stat_000000L_20070815_120000V.stat
> > -rw-r--r--    1 lir      ncar         652568 Aug 20 16:05
> > point_stat_000000L_20070815_120000V_mpr.txt
> > -rw-r--r--    1 lir      ncar         698412 Aug 20 16:05
> > point_stat_120000L_20070816_000000V.stat
> > -rw-r--r--    1 lir      ncar         579124 Aug 20 16:05
> > point_stat_120000L_20070816_000000V_mpr.txt
> > -rw-r--r--    1 lir      ncar         761574 Aug 20 16:05
> > point_stat_240000L_20070816_120000V.stat
> > -rw-r--r--    1 lir      ncar         631498 Aug 20 16:05
> > point_stat_240000L_20070816_120000V_mpr.txt
> > -rw-r--r--    1 lir      ncar         740520 Aug 20 16:05
> > point_stat_360000L_20070817_000000V.stat
> > -rw-r--r--    1 lir      ncar         614040 Aug 20 16:05
> > point_stat_360000L_20070817_000000V_mpr.txt
> > -rw-r--r--    1 lir      ncar         791340 Aug 20 16:05
> > point_stat_480000L_20070817_120000V.stat
> > -rw-r--r--    1 lir      ncar         656180 Aug 20 16:05
> > point_stat_480000L_20070817_120000V_mpr.txt
> >
> > Script:
> > /ptmp/lir/test/2009_t8_15km/verify_met2.0/test% point_stat_gsi.ksh
> > *** Running POINT_STAT on WRF OUTPUT ***
> > ***          UGRD                ***
> > GSL_RNG_TYPE=mt19937
> > GSL_RNG_SEED=2412285258
> > Forecast File:
> >
> /ptmp/lir/data/2009_t8_15km/verify_met2.0/gsi/wpp/2007081512/postprd/wrfprs_d01.000
> > Climatology File: none
> > Configuration File: ./config/PointStatConfig_GSI.UGRD
> > Observation File:
> > /ptmp/lir/data/2009_t8_15km/verify_met2.0/ob_nc/2007081512/ob.nc.qc2
> >
> > ----------------------------------------
> >
> > Reading records for UGRD/Z10.
> > For UGRD/Z10 found 1 forecast levels and 0 climatology levels.
> >
> >
> > Thanks for your support,
> >
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > Met_help mailing list
> > Met_help at mailman.ucar.edu
> > http://mailman.ucar.edu/mailman/listinfo/met_help
>

-- 
Ruifang

Mesoscale & Microscale Meteorology Division
Phone: 303-497-8938
Office:  FL3-3085
Email:  lir at ucar.edu
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/met_help/attachments/20090821/64ea9742/attachment.html 