The CoAgMet Network: Overview, History and How It Works Wendy Ryan Colorado Climate Center Colorado State University

History ► In the early 1990’s, CSU extension plant pathologists and ARS scientists decided to collaborate efforts to collect detail agricultural weather data. ► Standard instruments and data collection platform were selected and a small network of stations was deployed in fully irrigated agriculture. ► As the network grew, the Colorado Climate Center became increasingly interested in using the data, began daily data collection, quality control and built a web interface to distribute data and products to users across the state.

CoAgMet 1992

CoAgMet 1997

CoAgMet 2002

CoAgMet Today

Overview ► Currently there are 64 stations ► Data are collected on hourly and daily time steps and include: temperature, humidity, solar radiation, wind speed and direction, and soil temperatures. ► Data and graphics are available online: ccc.atmos.colostate.edu/~coagmet

What do the stations measure?

Cup anemometer and wind vane: Wind speed, direction and gusts Pyranometer: Solar radiation Tipping bucket rain gage Soil temperatures Temperature/Humidity sensor in radiation shield Solar panel powers the station Data collection platform (DCP) 2 m -5/-15 cm 1-3 m Above all else facing South

Data Collection Platform Datalogger Power supply Communications device (cellular modem) Incoming sensor cables

Why these measurements? ► The main goal of CoAgMet is to calculate evapotranspiration (ET) from meteorological measurements. ► Several models exist that vary by input data and complexity:  Penman-Monteith – physically based  Kimberly-Penman – physically based  Hargreaves – empirical temperature based  Standardized ASCE Equation – attempts to standardize calculations to make them more comparable ► The standard CoAgMet station collects the elements needed to calculate evapotranspiration.

Temperature/Humidity Temperature: During the growing season, higher temperatures cause the plant stoma to open resulting in greater transpiration. Humidity: The higher the humidity the less transpiration will occur (more transpiration occurs in dryer air)

Wind Movement ► As air moves across plants it will cause more transpiration as saturated air (from transpiration) around the plant is mixed and dryer air can move in.

Solar Radiation ► Alfalfa only reflects about 25% of incoming solar energy which leaves ample solar energy to drive ET rates. ► ET trends follow a similar pattern as seasonal solar radiation and air temperature.

Precipitation ► While precipitation data is not explicitly used in the ET equations, it does affect crop coefficients used at different locations. ► Monitoring precipitation also provides an idea of soil moisture availability at the station.

Soil Temperatures ► Having the temperature of the soil aids in knowing when the soil has warmed enough to plant. ► Soil temperature also gives an indication of the amount of ground cover at the station.

Problems with CoAgMet ► Missing data ► Site exposure ► Routine maintenance

Missing/Questionable Data ► Due to various problems that occur to remote weather stations, missing data causes problems for users. ► Battery failure and communications problems are the most common. ► Even if the whole station doesn’t fail, sensors go bad and can leave some elements missing until the station is serviced.

Unfortunately, data are not complete at all stations Unfortunately, data are not complete at all stations Missing Data

Some Data are Questionable

Site Exposure ► One of the assumptions of the evapotranspiration equations is that water is not limited (i.e. in full irrigation). ► Some stations are not located in ideal “reference” conditions. ► Some stations have obstructions (buildings/crops) that affect the amount of wind in certain directions. ► The exposure of the site can have an impact on the data and over/under estimate reference ET.

Siting and Exposure FTC01 Fort Collins AERC has appropriate citing for reference ET calculations HOT01 Hotchkiss is not ideally cited for reference ET calculations The Good…and the Not so Good

Routine Maintenance ► Due to the fact that CoAgMet is run by collaborations and operates on a limited budget, routine maintenance is difficult with such a large network.  There is no full time CoAgMet technician. ► Our goal is to service a station once every 2 years. ► Data users should be cautious and thoroughly quality control the data they are using.

Possible Solutions? ► Efforts are being made to fill in missing data using relationships with nearby stations.  This data would be flagged when presented on the website. ► Our website now color codes stations according to their irrigation are classified as: full irrigation, partial irrigation and dryland.  Making this information available to the public allows them to know more about their data source.

Possible Solutions? ► We due our best with limited funds to keep a maintenance schedule but it is very difficult. ► If we are not able to keep high standards for our weather stations, some current stations may need to be discontinued in the near future. ► If you value the CoAgMet network, consider donating funds to help sponsor a station in your area!

CoAgMet Website Demonstration

The Colorado Climate Center Home Page ccc.atmos.colostate.edu /

Hourly Climate Data Plots Click Here

Hourly Climate Data Plots GLY03 Greely June 9, 2007 through June 15, 2007 Relative Humidity Temperature

Daily Climatic Summary Click Here

Daily Climatic Summary

Monthly Station Summaries Click Here

Monthly Station Summaries KSY01 – Kersey Aug. 2007

Daily Regional Climatic and ET Comparison Click Here

Daily Regional Climatic and ET Comparison North Central Region, May 30, 2007

Crop Specific ET Reports Click Here

Crop Specific ET Reports Calculates multi-day ET for: alfalfa, corn, dry beans, small grain, sugar beets, potatoes, onion, winter wheat, turf grass, and reference ET, via Penman-Monteith or Kimberly-Penman

CoAgMet web access: