TITLE: SMEX02 Iowa Mesonet Data CONTACTS: Dr Dennis Todey 1571 Agronomy Hall Iowa State University Ames, IA 50010 Ph. 515.294.8734 Daryl Herzmann 3010 Agronomy Hall Iowa State University Ames, IA 50010 Ph. 515.294.5978 1.0 DATA SET OVERVIEW This data set contains hourly resolution surface meteorological data from the Iowa Environmental Mesonet. These data are made available through Iowa State University and include data for locations throughout the state of Iowa from a variety of networks including the Automated Weather Observing System (AWOS), the Automated Surface Observing System (ASOS), the Iowa Department of Transporation Roadway Weather Information System (RWIS), the Iowa State University AgClimate Network, the United States Department of Agriculture Natural Resources Conservation Service (USDA/NRCS) Soil Climate Analysis Network (SCAN), the National Weather Service Cooperative Network, Data Collection Platforms (DCPs), and the KCCI-TV8 SchoolNet. This data set covers the period from 1 June to 31 July 2002. The data are in GEMPAK format. NOTE: The AWOS precipitation values in this data set have problems Please see the data remarks section below (section 5.0) for further information. The 1-minute AWOS data set also available from JOSS (http://www.joss.ucar.edu/cgi-bin/codiac/dss?80.003) has correct precipitation. 2.0 INSTRUMENT DESCRIPTION 2.1 ASOS The Automated Surface Observing System (ASOS) is considered to be the flagship automated observing network. Located at airports, the ASOS stations provide essential observations for the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD). The primary function of the ASOS stations are to take minute-by-minute observations and generate basic weather reports. Observations from the ASOS network are nationally monitored for quality 24 hours per day. Depending on the trouble, maintenance can be performed on the same day. Information on the ASOS instrumentation can be found at the National Weather Service (NWS) ASOS web page at: http://205.156.54.206/asos/ or at the Federal Aviation Administration (FAA) automated weather sensors web site at: http://www.faa.gov/asos/asos.htm 2.2 AWOS Automated Weather Observing System (AWOS) stations are often grouped together with the ASOS stations, but they are not the same. Like the ASOS, the AWOS sensors primarily provide the aviation community with current weather observations. The data is also transmitted by phone lines or satellite uplinks for use by other agencies. The AWOS sites are either federally operated by the FAA or some of them are locally maintained by state agencies. Some information on AWOS can be found at the Federal Aviation Administration Automated Weather Sensors page at: http://www2.faa.gov/asos/ 2.3 NWS Cooperative Network The National Weather Service [NWS] Cooperative Observer Program [COOP] is a nation-wide network of people making weather and climate observations. According to their website, there are 11,700 volunteer observers. [1] These volunteers are invaluable in times of severe weather and heavy snowfall. Their observations also provide a 'ground truth' to compare against remote sensing techniques. Information on the NWS Cooperative Observer Program is available at: http://www.nws.noaa.gov/om/coop/ 2.4 DCPs The Geostationary Operational Environmental Satellites (GOES) Data Collection Platforms (DCPs) are a set of hydrologic and meteorologic data collection points. The DCPs are a collection of networks owned and operated by a host of entities. The IEM receives this dataset from our UNIDATA feed, which contains the products produced by the Office of Hydrological Development of the National Weather Service. Further information on these data is available at: http://www.nws.noaa.gov/oh/hads/ 2.5 ISU AgClimate Information on this network is available at: http://mesonet.agron.iastate.edu/agclimate/index.php 2.6 RWIS The Iowa Department of Transportation maintains a set of observing stations located along major roads in the state. These stations measure pavement temperatures as well as atmospherics. The DOT has a good website called WeatherView, which contains recent obs and a wealth of other information. For further information see: http://www.weatherview.dot.state.ia.us/ 2.7 USDA/NRCS SCAN Information on this network is available at: http://www.wcc.nrcs.usda.gov/scan/ 2.8 SchoolNet As the name implies, these automated weather stations are located at schools throughout the state. Currently, KCCI-TV (Des Moines, IA) and KELO-TV (Sioux Falls, SD) have graciously provided the IEM with the ability to process data from their observing networks. We are pursuing other TV stations, for their networks as well. Many of the school net stations are not located in good Meteorological locations. While the stations may be accurate, their data may not be representative of the area in general. Often, they are placed on top of buildings and may have obstructions which could skew wind and temperature readings. The stations are placed at schools for educational purposes and to get students interested in the weather. 2.9 Station Locations Station location information is included within the data set. 3.0 DATA COLLECTION AND PROCESSING Information on the collection and processing of these data can be found at the Iowa Environmental Mesonet page: http://mesonet.agron.iastate.edu/ UCAR/JOSS conducted no processing or quality control on these data. 4.0 DATA FORMAT AND FILE NAMING 4.1 Data Format These data are in General Meteorology Package (GEMPAK) format. For information on GEMPAK see: http://www.unidata.ucar.edu/packages/gempak/ 4.2 File Naming conventions 020724_meso.gem where: 02 is the year (2002) 07 is the month (July) 24 is the date gem is the format (GEMPAK) 5.0 DATA REMARKS The 1-minute observations from the Iowa AWOS are available from JOSS at the following location: http://www.joss.ucar.edu/cgi-bin/codiac/dss?80.003 These 1-minute data files have the correct precipitation see below: Message from Daryl Herzmann (akrherz@iastate.edu) * Program Assistant -- Iowa Environmental Mesonet * http://mesonet.agron.iastate.edu Sent 10 April 2003: Anyway, most (not all) of these stations are outfitted with tipping buckets. All of you have been receiving the AWOS precipitation amounts from the raw METARs, but up until today, there has been a fundamental flaw with the observations. The site resets the hourly precipitation counter at :55 after the hour, but METARs were only relayed at :05, :25 and :45 after the hour. This would result in 10 minutes of missing potential rainfall data every hour. The Iowa Department of Transportation sends us their 1 minute interval data archive from the network at the end of every month. While looking at this dataset, I noticed this timing problem last summer. The Des Moines WFO and the Iowa Mesonet have been working closely with the DOT to get this problem resolved. And today it has been. The Iowa AWOS sites are now reporting at :15, :35 and :55 after the hour, which eliminates the timing issue. 6.0 REFERNCES Iowa Environmental Mesonet page: http://mesonet.agron.iastate.edu/