GCIP/LSA-NW EAOP 1999 Great Plains Region AgriMet Network Hourly Surface Data in QC Format 1.0 General Description The Great Plains Region AgriMet Data System Hourly Surface Data in QC format is one of several surface datasets provided in the GEWEX Continental-Scale International Project (GCIP) Large Scale Area-North West (LSA-NW) Enhanced Annual Observing Period (EAOP) 1999. This dataset contains data for the GCIP LSA-NW EAOP-99 domain and time period (01 April 1999 through 31 March 2000). The GCIP LSA-NW EAOP-99 domain is approximately 90W to 115W longitude and 36N to 51N latitude. These data were not quality controlled by the University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS). 2.0 Detailed Data Description AgriMet is a satellite-linked, weather and evapotranspiration (ET) reporting network operated by the USDI Bureau of Reclamation. The Great Plains Region AgriMet Data System consists of 14 AgriMet stations operating in Montana. More information on these AgriMet sites can be found at: http://www.gp.usbr.gov/agrimet/agrimet.htm. Each AgriMet station measures temperature, accumulated solar radiation, dewpoint temperature, relative humidity, wind direction and wind gust speed every 15 minutes, as well as accumulated precipitation, average wind speed and the wind run every hour. All stations except four use a Belfort rainfall gage that utilizes a weighing mechanism to measure both liquid and frozen precipitation. The gage initially contains an anti-freeze mix to ensure the precipitation does not freeze and damage the gage, as well as mineral oil to prevent evaporation losses. The anti-freeze and mineral oil mixtures are refreshed once or twice yearly during visits to the site. Stations BFTM, BOMT, GFMT and HVMT use a tipping bucket precipitation gage that does not accurately measure frozen precipitation. The only frozen precipitation measured by the gage is precipitation that collects on top of it and melts in warmer weather. The precipitation values for these four stations have been flagged "D" for questionable data. The 15 minute AgriMet data is located in the Great Plains Region AgriMet Network Specials Surface Data in QC format dataset. Below is the description of a typical AgriMet station: Telecommunications Equipment (Manufacturer) * Data Collection Platform, Model 8004 (Sutron Corporation) * YAGI antenna & cable, Model 8200 A * 100 amp-hr battery & cable, #8200 PSB * Solar panel & cable, Model SX-10 * Integrator,solar * 190 amp-hr battery (Exide Corporation) * Integrator,solar (USDA-ARS (Burgess) * Integrator,wind run (USDA-ARS (Burgess) Sensors * Thermistor, YSI #44212 (Yellow Springs Instruments) * Wind Monitor #05103 (R.M.Young) * Pyranometer, Model LI-200SB (Li-Cor) * Relative Humidity Probe, Model 2013A (Texas Electronics) * Relative Humidity Probe, Model HMP-35A (Vaisala) * Tipping Bucket Rain Gage, 6010 & 6011-A (Qualimetrics) * Precipitation Collector, 12 inch (Belfort) 2.1 Detailed Format Description The GCIP LSA-NW EAOP-99 Hourly Surface Data contains ten metadata parameters and 38 data parameters and flags. The metadata parameters describe the station location and time at which the data were collected. The time of observation is reported both in Universal Time Coordinated (UTC) Nominal and UTC actual time. Days begin at UTC hour 0100 and end at UTC hour 0000 the following day. The data parameters are valid for the reported times. Missing values are reported as 9's in the data field. The table below details the data parameters in each record. Several data parameters have an associated Quality Control (QC) Flag Code. For a list of possible QC Flag values see the Quality Control Section 3.0. Parameters Units ---------- ----- Date of Observation UTC Nominal Time of Observation UTC Nominal Date of Observation UTC actual Time of Observation UTC actual Network Identifier Abbreviation of platform name Station Identifier Network Dependent Latitude Decimal degrees, South is negative Longitude Decimal degrees, West is negative Station Occurrence Unitless Station Elevation Meters Station Pressure, QC flag Hectopascals (mb) Reported Sea Level Pressure, QC flag Hectopascals (mb) Computed Sea Level Pressure, QC flag Hectopascals (mb) Dry Bulb Temperature, QC flag Celsius Dew Point, QC flag Celsius Wind Speed, QC flag m/s Wind Direction, QC flag Degrees Total Precipitation, QC flag mm Squall/Gust Indicator Code Value Squall/Gust Value, QC flag m/s Present Weather, QC flag Code Value Visibility, QC flag Meters Ceiling Height (first layer) Hundreds of feet Ceiling Flag (first layer), QC flag Code Value Cloud Amount (first layer), QC flag Code Value Ceiling Height (second layer) Hundreds of feet Ceiling Flag (second layer), QC flag Code Value Cloud Amount (second layer), QC flag Code Value Ceiling Height (third layer) Hundreds of feet Ceiling Flag (third layer), QC flag Code Value Cloud Amount (third layer), QC flag Code Value The list of code values for the Present Weather is too large to reproduce in this document. Refer to WMO, 1988 for a complete list of Present Weather codes. The code values for the Squall/Gust Indicator are: Code Definition ---- ---------- blank No Squall or Gust S Squall G Gust The code values for the Ceiling Flag Indicator are: Code Definition ---- ---------- 0 None 1 Thin 2 Clear below 12,000 feet 3 Estimated 4 Measured 5 Indefinite 6 Balloon 7 Aircraft 8 Measured/Variable 9 Clear below 6,000 feet (AUTOB) 10 Estimated / Variable 11 Indefinite / Variable 12 12-14 reserved 15 Missing The code values for the Cloud Amount Indicator are: Code Definition ---- ---------- 0 0 ( or clear) 1 1 okta or less, but not zero or 1/10 or less, but not zero 2 2 oktas or 2/10-3/10 3 3 oktas or 4/10 4 4 oktas or 5/10 5 5 oktas or 6/10 6 6 oktas or 7/10-8/10 7 7 oktas or more, but no 8 oktas or 9/10 or more, but not 10/10 8 8 oktas or 10/10 (or overcast) 9 Sky obscured by fog and/or other meteorological phenomena 10 Sky partially obscured by fog and/or other meteorological phenomena 11 Scattered 12 Broken 13 13-14 Reserved 15 Cloud cover is indiscernible for reasons other than fog or other meteorological phenomena, or observation is not made. 2.2 Data Remarks Wind speed values are averaged over the hour ending with the measurement time. Stations BFTM, BOMT, GFMT and HVMT do not accurately measure frozen precipitation. The precipitation values for these stations have been flagged "D". 3.0 Quality Control Processing This data was not quality controlled by UCAR/JOSS. See Table 3-1 for a list of the possible quality control flags and their meanings. Table 3-1 - Quality Control Flags QC Code Description ------- ----------- U Unchecked G Good M Normally recorded but missing. D Questionable B Unlikely N Not available or Not observed X Glitch E Estimated C Reported value exceeds output format field size or was negative precipitation. T Trace precipitation amount recorded I Derived parameter can not be computed due to insufficient data. 4.0 References The Great Plains Cooperative Agricultural Weather Network (AgriMet) http://www.gp.usbr.gov/agrimet/agrimet.htm; May 30, 2002 Grove, Tim, 2002, AgriMet, USDI Bureau of Reclamation Precip Gages, information supplied with data