[Met_help] question about point station verification

John Halley Gotway johnhg at rap.ucar.edu
Fri Jun 20 09:23:32 MDT 2008


MET can read the GRIB output file from the WRF PostProcessor directly.  It reads the data in and extracts the grid information from the GRIB file.

In the Point-Stat configuration file, you need to specify how you would like to accumulate statistics.  You can specify the regions for accumulation using the predefined grids, by defining polylines, 
or listing individual stations.  So if, for example, you list 1 grid, 2 polylines, and 3 station ids, Point-Stat will accumulate stats over all 6 masking regions you chose.

If you would like to just sum statistics up over your whole domain, I'd suggest defining a lat/lon polyline that fully contains your domain.  For example, just define a polyline (similar to the 
example polylines in the METv1.0/data/poly directory) but with only 4 points in it.  And make sure your domain is fully contained inside those 4 lat/lon points.

When you specify "mask_stations", Point-Stat looks for them in the OBSERVATIONS.  You don't need to do anything for your domain.  You just need to set your "mask_stations" to one or more of the 
station id's that exist in the observation file you're using.

Hope that helps.


RUAN Tao wrote:
> John,
>    Thank you for your reply.
>    Yeah, I am waiting the new version, but I am skimming the user guide.
> In fact, can the point_stat read the WRF Post-Processor output
> directly, or I have to do some work for that?
>    For the mask, there are 3 options in point_stat tools. As you said,
> they are optional for mask defining?  And whether MET will read the all
> lat lon of WRF output from the GRIB file generated by WRF Post
> Processor?
>    If I define the ID in mask_stations, will the MET to find them out in
> observation file? If so, I don't need to do anything for my domain ?
>> LJ,
>> The METv1.0 tarball available on the website has NOT been updated with the
>> fixes listed on the "known problems" page.  Sorry for the inconvenience,
>> but you'll need to grab those manually.
>> We're getting ready for the release of METv1.1 in the next month or so
>> which will include some upgrades and many bug fixes.  I suggest you grab
>> the new version when I becomes available.  We'll send
>> out an email to all the registered users at that point.
>> Regarding your question, we require users to specify a masking region to
>> define the areas over which they would like to accumulate their
>> statistics.  In Point-Stat, those masking regions may either be
>> a grid, a polyline, or the name of individual stations.  If you'd like to
>> accumulate statistics over your entire domain, I'd suggest defining a
>> lat/lon polyline that fully encompasses your domain.
>> Then list that polyline in the configuration file.  The polyline does not
>> need to be exactly along the boundary of your domain.  Instead, just
>> choose 4 lat/lon corner points that fully encompass your
>> domain.
>> Does that make sense?
>> Thanks,
>> John Halley-Gotway
>> johnhg at ucar.edu
>> RUAN Tao wrote:
>>> MET help,
>>>     I would like to use the MET to verify the WRF output with my
>>> observation data. But as mentioned in the USER guide, for point-stat
>>> tools, a mask_grids is needed, and any new grid would require code
>>> changes.  Does that means I have to change the code for my case? Are
>>> some options like those in model for defining the grid available? If
>>> not, perhaps it is quite difficult for others employing MET to verify
>>> their own case.
>>>     How can I do for using MET in my case?  Meanwhile, I find some bug
>>> fixes are available. And If I download the MET now , do I need to
>>> replace those fixes?
>>>      Thank you for any information.
>>> LJ(RUAN Tao)
>>> _______________________________________________
>>> Met_help mailing list
>>> Met_help at mailman.ucar.edu
>>> http://mailman.ucar.edu/mailman/listinfo/met_help
> LJ(RUAN Tao)

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