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.