TITLE:  Automated Surface Observing System (ASOS) 1-min Data
        [NCAR/EOL]


CONTACTS:

Steve Williams
NCAR/EOL
P.O. Box 3000
Boulder, CO 80307-3000

phone: 303-497-8164
email: sfw@ucar.edu


1.0  DATA SET OVERVIEW


This data set contains 1-minute resolution surface meteorological data
from the Automated Surface Observing System (ASOS) stations located
across the United States.  These data were retrieved from the National Climatic
Data Center (NCDC) for the T-REX period (March and April 2006).  The data set
is comprised of two types of files om1 and om2 described below.  Each file
is a compressed tar file containing one month of data with individual files
for each station in the United States.  The data are in ASCII.


2.0  INSTRUMENT DESCRIPTION


2.1  Instrumentation information

Information on the ASOS instrumentation can be found at the National
Weather Service (NWS) ASOS web page at:
http://www.nws.noaa.gov/asos/
or at the Federal Aviation Administration (FAA) automated weather
sensors web site at:
http://www.faa.gov/asos/asos.htm

Also the following documents are included with your order:
ASOS_Ready_Ref_Guide.pdf
asos_users_guide.pdf
asos_users_guide_app.pdf

2.2  Station Locations

See the document ASOS-STATIONS.TXT included with your order.  Station locations are from
the NOAA Multi-Network Metadata System.


3.0  DATA COLLECTION AND PROCESSING


NCAR/EOL conducted no processing or quality control on these data.

For information on ASOS data collection and processing please see:
The ASOS User's Guide and Appendices and the ASOS Ready Reference
Guide which have all been included with your data order.
Here are the file names:
ASOS_Ready_Ref_Guide.pdf
asos_users_guide.pdf
asos_users_guide_app.pdf

Further information is also available at:
The NWS ASOS Home Page: http://www.nws.noaa.gov/asos/
or at the FAA Automated Weather Sensor Home Page:
http://www.faa.gov/asos/asos.htm
or at the National Climatic Data Center Data Documentation for Data Set 3285
(DSI-3285) ASOS Surface 1 Minute Data included with your order as td3285.pdf.


4.0  DATA FORMAT AND FILE NAMING

4.1  File Naming conventions

Files downloaded from NCDC have names like:

om1_200603.tar.Z
where:
	om1 indicates the page the file contains data from (see below)
        2006 is the four digit year
        03 is the two digit month


4.2  Data Format
 
What follows is a very short description of the ASOS formats.  Further
information can be found in the ASOS documents included with your order.
Datafiles downloaded from NCDC contain an entire month of a single 
section (or "LISTING") for a single station.

4.2.1 LISTING LEDWI

No information yet.

4.2.2 LISTING 12HR PAGE #1

NCDC files with names beginning 64050 contain data for LISTING 12HR PAGE #1 
only.  In place of the column UTC shown below, they contain the following two 
columns:

STN - The Weather Bureau, Army, Navy (WBAN) numeric station ID followed by the
      NCDC alphanumeric station id (no spaces)
TIME - The NCDC alphanumeric station id followed by the 4-digit year, 2-digit 
       month, and 2-digit day in local standard time, 2-digit hour and minute 
       in local standard time, and 2-digit hour and minute in UTC.

All other columns are the same as the UCAR/JOSS dialed datafiles.

The columns in the UCAR/JOSS dialed datafiles are as follows:
UTC - UTC time (hhmm)
VIS1 - Visibility extinction coefficient sensor #1
D/N1 - Day/Night indicator sensor #1
VIS2 - Visibility extinction coefficient sensor #2
D/N2 - Day/Night indicator sensor #2
VIS3 - Visibility extinction coefficient sensor #3
D/N3 - Day/Night indicator sensor #3
WIND DIR/SPD - 2-minute average wind direction (degrees) and wind speed
               (knots)
5SEC WIND - Greatest 5-sec average wind speed (and corresponding direction)
            during past minute.
RVR - Runway Visual Range

4.2.3 LISTING 12HR PAGE #2

NCDC files with names beginning 64060 contain data for LISTING 12HR PAGE#2
only. In place of the column UTC shown below, they contain the following two
columns:

STN - The Weather Bureau, Army, Navy (WBAN) numeric station ID followed by the
      NCDC alphanumeric station id (no spaces)
TIME - The NCDC alphanumeric station id followed by the 4-digit year, 2-digit 
       month, and 2-digit day in local standard time, 2-digit hour and minute 
       in local standard time, and 2-digit hour and minute in UTC.

All other columns are the same as the UCAR/JOSS dialed datafiles.

The columns in the UCAR/JOSS dialed datafiles are as follows:
UTC - UTC time (hhmm)
WX - Present Weather Type
TS - 
PRECIP - 1-minute precipitation (inches)
SUN
SNOW
ZR
PRESS1 - Barometric pressure sensor #1 (inches of mercury)
PRESS2 - Barometric pressure sensor #2 (inches of mercury)
PRESS3 - Barometric pressure sensor #3 (inches of mercury)
TEMP - Air temperature (degrees F)
DEWPT - Dew point (degrees F)

4.2.4 LISTING 12HR PAGE #3

The columns in the UCAR/JOSS dialed datafiles are as follows:
UTC - UTC time (hhmm)
15-MINUTE PRECIPITATION AMOUNT - (inches)

4.2.5 LISTING 12HR PAGE #4

Ceilometer #1

No information yet.

5.0  DATA REMARKS


6.0  REFERENCES


None.