This info should be filed with ds464.0 since it contains info
about the problems with 1997 data.
        

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From Dennis.Keyser@noaa.gov Wed Oct  1 10:52:50 1997
Subject: Corrections to NCEP Office Note 124/29 SURFACE files


In February 1997, NCEP converted it's observational data processing
format from Office Note 29/124 to WMO BUFR.  This effort was part of
the larger transition of data processing from the HDS machine to the
UNIX platform on the workstations and the Cray machines.

Since that time, NCEP has continued to provide Office Note 29/124
observational data sets to the outside world.  Of course, we also
provide the BUFR data sets.  The Office Note data sets are generated
from the BUFR data sets.  In the hectic pace of the initial conversion
effort, the emphasis was placed on reformatting the basic state
variables and time-space information correctly.  Since that time,
users both inside and outside of NCEP have pointed out that several
parameters in the surface land (ADPSFC) and marine (SFCSHP) ON124
files are incorrect.  I have now had the opportunity to address these
remaining problems.  My results follow:


--> The 5 missing/incorrect parameters noted by NCDC have all been
corrected as of 0000 UTC 01 October:

 1.   Visibility (VV) is now present in Cat. 51 (was 00).
 2.   The pressure tendency/characteristic (app) group is now coded
       correctly in Cat. 51.
 3.   The height of cloud base above ground (h) is now present in Cat.
       51 (was missing).
 4.   The 8 group for clouds is now present in Cat. 51 (was missing).
 5.   The I sub x indicator is now present in the header (was
       missing).


--> The following parameters have also been corrected as of 0000 UTC
01 October:

 1.  Synoptic format flag in header.
 2.  Automatic station type in header.
 3.  Converted hourly flag in header.
 4.  I sub p in header (precipitation inclusion).
 5.  Past (W sub 1, W sub 2) and present (WW) weather in Cat. 51.
 6.  Maximum and minimum temperature in Cat. 51.
 7.  06-hr precip. amount in Cat. 52.
 8.  Snow depth in Cat. 52.
 9.  24-hr precip. amount in Cat. 52.
10.  Duration of precip. observation in Cat. 52.
11.  Period of waves in Cat. 52.
12.  Height of waves in Cat. 52.
13.  Direction of swell waves in Cat. 52.
14.  Period of swell waves in Cat. 52.
15.  Height of swell waves in Cat. 52.
16.  Ship's course in Cat. 52.
17.  Ship's speed in Cat. 52.
18.  Code figures 81-85, 98 in Cat. 8.


--> The following parameters remain missing because they are not
present in the BUFR file:

 1.  I sub w in header (indicator for wind speed).
 2.  Special phenomena, general in Cat. 52.
 3.  Special phenomena, detailed in Cat. 52.
 4.  Water equivalent of snow and/or ice in Cat. 52.
 5.  Plain language data in Cat. 9.


This represents my final major correction to the Office Note 29/124
format data sets.  NCEP encourages all users of our data to convert
their programs to point to the BUFR files which are much more complete
and correspond to the WMO standard.
     
    
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Dennis A. Keyser            Environmental Modeling Center  
dennis.keyser@noaa.gov      National Centers for Environmental Prediction
Voice: 301-763-8056,x-7223  Fax: 301-763-8545
      
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