[Met_help] Question about MET (UNCLASSIFIED)

[John Halley Gotway]

John,

That's correct.  PB2NC enables you to filter the observations in various ways: message type, station id, time range, geographical area, elevation, report type, observation type, and quality mark
value.  However, ASCII2NC doesn't do any of that filtering.  We assume that when a user constructs an observation file themselves in ASCII format, they've only retained the observations they'd
actually like to use in their verification.

However, let me point out that when you use the output of ASCII2NC in Point-Stat, you are able to specify which variables/levels you'd like to verify, which observation message types to use, over what
geographic areas to compute statistics, and what matching time window around the forecast's valid time to use.

We added these filtering options to PB2NC mainly for those people using PrepBufr files containing global or CONUS observations, but verifying over a much smaller domain.  By filtering many
observations out in PB2NC, we enable Point-Stat to run much faster rather than it would if it had to read the entire global observation data set.

If you need to do additional filtering of your ASCII observations before using them in the verification, you may be able to do so by writing some simple scripts to filter out the subset of
observations you'd actually like to use.

Hope that helps.

Thanks,
John

Raby, John (Civ, ARL/CISD) wrote:
> Classification: UNCLASSIFIED
> Caveats: NONE
> 
> John - 
> 
> Thanks for the quick response. So, the config file really just allows you to
> filter the output of the PB2NC tool to your desired specs while ASCII2NC
> allows no filtering. It just passes through everything it sees in the input
> ascii file.
> 
> R/
> John
> 
> 
> -----Original Message-----
> From: John Halley Gotway [mailto:johnhg at ucar.edu] 
> Sent: Friday, April 09, 2010 12:22 PM
> To: Raby, John (Civ, ARL/CISD)
> Cc: Tressa Fowler; Brown, Bob (Civ, ARL/CISD); Flanigan, Robert (Civ,
> ARL/CISD); Passner, Jeff (Civ, ARL/CISD)
> Subject: Re: Question about MET (UNCLASSIFIED)
> 
> John,
> 
> ASCII2NC is really not a complex tool at all.  All it does is reformat an
> ASCII representation of point observations into a NetCDF version of the
> file.  It does little to no error checking - so whatever you have in the
> "Message_Type" column of the ASCII data will simply be passed through to the
> output NetCDF file.
> 
> So you should be fine.  Just let us know if more questions come up.
> 
> Thanks,
> John
> 
> Raby, John (Civ, ARL/CISD) wrote:
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>> John or Tressa -
>>
>> We are preparing to acquire and use MADIS observational data for the 
>> large and smaller nested domains Barb Sauter was using over UT in MET. 
>> We would like to use MADIS exclusively over each domain since it 
>> contains significantly more surface observations from the MESOWEST 
>> mesonet and other mesonet sources in addition to the standard METAR 
>> data available using the PreBUFR data source.
>>
>> We were thinking about using both sources together (PrepBUFR for upper 
>> air and MADIS for surface mesonet) but do not want to deal with 
>> duplicate observations if we can avoid it.
>>
>> Right now we are processing the mesonet (surface obs) data using the 
>> ASCII2NC tool to make it ready for ingest into MET. We would like to 
>> acquire upper air data from MADIS which contains radiosonde and aircraft
> acars data.
>>
>> I noticed that the configuration file for the PB2NC specifies the 
>> message_type explicitly for all message types including ADPUPA, 
>> ADPSFC, VADWND, etc, confirming that these message types are handled. 
>> Barb Sauter specified all message types using [] so she could process 
>> ADPUPA, ADPSFC, AIRCFT and VADWND data from the PRepBUFR source.
>>
>> However, using the ASCII2NC tool does not require a config file, so I 
>> wasn't sure which message types were handled. Will the ASCII2NC tool 
>> process upper air data from MADIS?
>>
>> Thanks.
>>
>> R/
>> John
>>
>> Mr John W. Raby, Meteorologist
>> U.S. Army Research Laboratory
>> White Sands Missile Range, NM 88011
>> (575) 678-2004 DSN 258-2004
>> FAX (575) 678-1230 DSN 258-1230
>> Email: john.raby at us.army.mil
>>
>> Please begin using the email address within this signature block for 
>> all future correspondence.  The current @arl.army.mil address will be 
>> decommissioned in upcoming months.
>>
>> "When you can measure what you are speaking about and express it in 
>> numbers, you know something about it, but when you cannot measure it, 
>> when you cannot express it in number, your knowledge is of a meagre 
>> and unsatisfactory kind". - Lord Kelvin
>>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>>
> Classification: UNCLASSIFIED
> Caveats: NONE
> 
>