GCIP LSA-NW EAOP 1999 Colorado Agricultural Meteorological Network (COAGMET) Hourly Surface Data in QC format 1.0 General Description The Colorado Agricultural Meteorological Network (COAGMET) 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 Unversity Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS). 2.0 Detailed Data Description The Colorado Agricultural Meteorological Network (COAGMET) consists of 32 automated weather stations in Colorado operated by the Colorado Climate Center. For more information on COAGMET visit the following website: http://ccc.atmos.colostate.edu/~coag/ Below is the description of a typical COAGMET station. Most stations have a similar configuration but sensors, dataloggers and siting vary somewhat throughout the network. Only the temperature, relative humidity, vapor pressure, wind speed, wind direction and precipitation values are used to create the final dataset, but the description of the sensor for every parameter is included here for reference. The complete dataset is available from codiac in the original COAGMET format as the dataset "GCIP/LSA-NW 99 Surface: COAGMET Hourly Surface Data". Temperature, wind speed and wind direction values are averaged over the hour ending with the measurement time. Dewpoint temperature is calculated by UCAR/JOSS using the formula from Bolton (1980) and the temperature, relative humidity and vapor pressure values from each station. Temperature and Relative Humidity * Model: Vaisala HMP35C Probe * Sensor Height: 1.5 meters * Temperature Specs o Temperature Measurement Range: -35 to 50 DegC o Thermistor Interchangeability Error: Typically <+-0.2 DegC over 0 DegC to 60 DegC; +-0.4 DegC at -35 DegC o Polynomial Linearization Error: <+-0.5 DegC over -35 DegC to 50 DegC * Relative Humidity Specs o RH Measurement Range: 0% to 100% o RH Accuracy (at 20 DegC) +- 2%, 0% - 90%; +-3% >90% o Temperature Dependence of RH Measurement: +-0.04% RH/DegC Wind * Model: R.M. Young 05103 Wind Monitor * Sensor Height: 2 meters * Wind Speed Specs o Range: 0-60 m/s o Starting Threshold: 1.0 m/s o Distance Constant (63% recovery): 2.7 m. * Wind Direction Specs o Range: 0-360 Deg. (355-360 open) o Starting Threshold 10 deg displacement: 0.9 m/s o Starting Threshold 5 deg displacement: 1.3 m/s Precipitation * Model: TE525 tipping bucket raingage * Specs o Sensor height >1m o Collector diameter - 154mm o 0.254mm/tip o accuracy +- 1% for precip of 50mm/hr or less o Operating temperature 0 to 50C (not accurate during winter) Solar Radiation * Model: Licor 200S Pyranometer * Specs o Sensor Height ~2m o 0-10 mv output range o Sensitivity typically 80 microamp/1000 W/m2 o Linearity Maximum deviation 1% up to 3000 W/m2 o Spectral response from 0.4 to 1.1 mu o Typical error under natural daylight +-3%, maximum +-5% Soil Temperature * Model: CSI Model 107 Soil Temp Probe (thermistor) * Specs o +- 0.4C for -33 to +48C all errors inclusive o Sensor depth 50mm and 150mm where two sensors used, 100mm where only one. Leaf Wetness Sensor * Model: CSI Model 237 - Circuit board with interlocking gold plated copper fingers, coated with flat latex paint to spread water layer. Measures electrical resistivity of water film. * Specs o Sensor height ~0.5m Data Logger * Model: Campbell Scientific CR10 * A picture of a CR10 installation can be found at: http://ccc.atmos.colostate.edu/~coag/ws01.gif Site Pictures * Dove Creek (dvc01) - http://ccc.atmos.colostate.edu/~coag/ws01.gif * Burlington (brl02) - http://ccc.atmos.colostate.edu/~coag/ws02.gif * Grand Junction (gjc01) - http://ccc.atmos.colostate.edu/~coag/ws03.gif 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 Temperature, wind speed and wind direction values are averaged over the hour ending with the measurement time. All stations use unheated precipitation gages, resulting in innacurate readings during the winter. All precipitation values have been flagged as "D" because of this. Dewpoint temperature is calculated by UCAR/JOSS using the formula from Bolton (1980) and the temperature, relative humidity and vapor pressure values from each station. 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 Bolton, D., 1980: The computation of equivalent potential temperature., Mon. Wea. Rev., 108, pp 1046-1053. Colorado State University, Cited 2002: CoAgMet Homepage [Available online from http://ccc.atmos.colostate.edu/~coag/] World Meteorological Organization (WMO), 1988: Manual on Codes Volume I, Part B - Binary Codes. WMO, Geneva, Switzerland.