[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

19990610: ASOS

Teresa,

The ASOS location heights are usually surveyed since most are deployed
at airports where the runway elevaltion is known.

Metar observations report mean sea level pressure (eg pressure reduced
to sea levl) and/or altimeter setting. Almost all stations report
altimeter setting since pilots need that measurement for landing.

From your previous list of stations:
Station    Location              On NOAAport
KSJT       SAN ANGELO, TX        Yes
KACV       EUREKA, CA            Yes
KRAL       RIVERSIDE, CA         Yes
KEKO       ELKO, NV              Yes
KBFI       SEATTLE, WA           Yes
KPRC       PRESCOTT, AZ          Yes
KDEN       DENVER, CO            Yes
KGTF       GREAT FALLS, MT       Yes
KGFX                             NO
KOLU       COLUMBUS, NE          Yes
KOKC       OKLAHOMA CITY, OK     Yes
KGRB       GREEN BAY, WI         Yes
KGWO       GREENWOOD, MS         Yes
XAND                             NO
KACY       ATLANTIC CITY, NJ     Yes
KDAY       DAYTON, OH            Yes
KBGR       BANGOR, ME            Yes
PABE       BETHEL, AK            Yes
PAOT       KOTZEBUE, AK          Yes
PASI       SITKA, AK             YES
PMNL                             NO


The 3 station you list that are not in our data stream are also not
in the NWS list of ASOS stations:
http://www.nws.noaa.gov/pub/modernize/asos.txt

Maybe typo in the station IDs- for example PHNL is Honolulu, KAND is
Anderson, SC.

For an example of Metar reports, here are those from Denver today from
12Z through 15Z, along with the decoded mean sea level pressure (PMSL)
Station pressure from altimeter setting (PALT), temperature (TMPC)
and dewpoint (DWPC)

KDEN 211153Z 20009KT 10SM FEW120 SCT250 14/07 A3003 RMK AO2 SLP097
T01440072 10167 20139 56008= 
  
KDEN 211253Z 20010KT 10SM FEW100 SCT200 16/08 A3003 RMK AO2 SLP096
T01610078=   
  
KDEN 211353Z 20009KT 10SM FEW100 SCT200 19/08 A3002 RMK AO2 SLP090
T01890083=   
  
KDEN 211453Z 20010KT 10SM FEW140 SCT250 22/10 A3001 RMK AO2 SLP083
T02220100 58004=


    STN  YYMMDD/HHMM      PMSL     PALT     TMPC     DWPC
    DEN    990621/1200   1009.70   832.43    14.39     7.22
    DEN    990621/1300   1009.60   832.43    16.11     7.78
    DEN    990621/1400   1009.00   832.16    18.89     8.28
    DEN    990621/1500   1008.30   831.88    22.22    10.00

As you see in the 12Z report, the altimeter setting
appears as A3003 (or 30.03 inches), while the reduced SLP 
is reported in the Remarks section as 1009.7mb.

Converting from Altimeter setting to station pressure requires use
of the station elevation.

Steve Chiswell
Unidata User Support



On Thu, 10 Jun 1999, Unidata Support wrote:

> 
> ------- Forwarded Message
> 
> >To: Unidata Support <address@hidden>
> >From: Teresa Van Hove <address@hidden>
> >Subject: Re: 19990421: 19990412: is ASOS data part of the unidata IDD flow?
> >Organization: GST
> >Keywords: 199906102122.PAA20245
> 
> Hi Chiz,
> 
> A couple questions on the ASOS data.  Do you know how 
> the ASOS height measurements are determined?  I suppose
> they are sea-level, so I'll have to apply a geoid model
> to compare to the GPS antennas, but how accurate are 
> the ASOS heights.  Chris pointed out to me that we 
> need to know the height differential between the ASOS
> and the GPS within a couple of meters.  Second question:
> are the pressures converted to sea-level height, or does
> the metar data stream contain the station measurement as
> well.  If only the sea-level height pressure is in the
> metar data stream is there one standard conversion formula
> to revert to station pressure or is the formula site 
> dependant?  A sample of the hourly data stream would
> still be helpfull too.
> 
> Thanks,
> Teresa
> 
> Unidata Support wrote:
> > 
> > Teresa,
> > 
> > We're out of our offices right now with the FUN thing- and
> > we've had our user committee meeting- so I haven't gotten back
> > to you sooner.
> > 
> > The FAA sites etc are in the metar stream, and we have perl decoder
> > that can convert the METAR into NetCDF. Also, we have a grib decoder for
> > converting NCEP model data into NetCDF files for using to calculate
> > the retrieval coefficients you would need. The standard IDD data stream
> > has 3 hourly NCEP output in a model called RUC (rapid update cycle/FSL).
> > I also have separate model data feeds with hourly RUC output if that
> > is necessary- its a lot of data, and can really tie up a machine.
> > 
> > I'll send you an output pf which stations in your list are in the
> > hourly data stream.
> > 
> > Steve Chiswell
> > Unidata User SUpport
> 
> >From address@hidden  Thu Jun 10 15:34:24 1999
> Received: from cosmic.cosmic.ucar.EDU (address@hidden [128.117.29.214])
>       by unidata.ucar.edu (8.8.8/8.8.8) with ESMTP id PAA20482
>       for <address@hidden>; Thu, 10 Jun 1999 15:34:24 -0600 (MDT)
> Keywords: 199906102134.PAA20482
> Received: from ucar.edu by cosmic.cosmic.ucar.EDU (8.8.7/ NCAR Mail Server 
> 04/10/90)
>       id PAA26433; Thu, 10 Jun 1999 15:34:24 -0600
> Sender: address@hidden
> Message-ID: <address@hidden>
> Date: Thu, 10 Jun 1999 15:32:31 -0600
> From: Teresa Van Hove <address@hidden>
> Organization: GST
> X-Mailer: Mozilla 4.51 [en] (X11; I; Linux 2.2.5-15smp i686)
> X-Accept-Language: en
> MIME-Version: 1.0
> To: Unidata Support <address@hidden>
> Subject: [Fwd: 19990421: 19990412: is ASOS data part of the unidata IDD flow?]
> Content-Type: text/plain; charset=us-ascii
> Content-Transfer-Encoding: 7bit
> 
> Sorry if this is a repeat, my machine crashed just as I 
> sent it the first time.
> 
> Teresa
> 
> 
> 
> Teresa Van Hove wrote:
> > 
> > Hi Chiz,
> > 
> > A couple questions on the ASOS data.  Do you know how
> > the ASOS height measurements are determined?  I suppose
> > they are sea-level, so I'll have to apply a geoid model
> > to compare to the GPS antennas, but how accurate are
> > the ASOS heights.  Chris pointed out to me that we
> > need to know the height differential between the ASOS
> > and the GPS within a couple of meters.  Second question:
> > are the pressures converted to sea-level height, or does
> > the metar data stream contain the station measurement as
> > well.  If only the sea-level height pressure is in the
> > metar data stream is there one standard conversion formula
> > to revert to station pressure or is the formula site
> > dependant?  A sample of the hourly data stream would
> > still be helpfull too.
> > 
> > Thanks,
> > Teresa
> > 
> > Unidata Support wrote:
> > >
> > > Teresa,
> > >
> > > We're out of our offices right now with the FUN thing- and
> > > we've had our user committee meeting- so I haven't gotten back
> > > to you sooner.
> > >
> > > The FAA sites etc are in the metar stream, and we have perl decoder
> > > that can convert the METAR into NetCDF. Also, we have a grib decoder for
> > > converting NCEP model data into NetCDF files for using to calculate
> > > the retrieval coefficients you would need. The standard IDD data stream
> > > has 3 hourly NCEP output in a model called RUC (rapid update cycle/FSL).
> > > I also have separate model data feeds with hourly RUC output if that
> > > is necessary- its a lot of data, and can really tie up a machine.
> > >
> > > I'll send you an output pf which stations in your list are in the
> > > hourly data stream.
> > >
> > > Steve Chiswell
> > > Unidata User SUpport
> 
> 
> ------- End of Forwarded Message
> 
>