New Extended Facilities Expand Flux Measurement Capabilities

 
Published: 29 November 2011
EBBR systems like the one shown here produce 30-minute estimates of the vertical fluxes of sensible and latent heat at the local surface.

Introducing: Anthony and Marshall—not new faces on the ARM Facility team, but places—locations near new “extended facilities” coming online at the ARM Southern Great Plains site in Oklahoma and Kansas. In all, eight new extended facilities have been established throughout the reduced SGP domain, now an area of approximately 22,500 square kilometers, or the approximate area of a modern climate model grid cell.

Centered around the SGP Central Facility, these extended facilities are equipped with a dense network of instruments—purchased through the Recovery Act—that measure the exchange of heat, moisture, and carbon dioxide near the ground. These sites and instruments are referred to as a surface flux network.

Surface Flux Network

Energy balance Bowen ratio systems (EBBR) are the cornerstone of this network and provide 30-minute estimates of vertical sensible and latent heat fluxes. For locations where EBBRs are difficult to employ, usually at the north edge of a field of crops, eddy correlation flux measurement systems (ECOR) are installed. The ECOR measures surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide. Surface energy balance systems (SEBS) are paired with the ECORs for comparing heat fluxes and provide sensor wetness information for data quality purposes.

This updated map of the SGP domain shows the location of the Central, intermediate, and extended facilities. Click to enlarge.

Collocated with the surface flux instrumentation, multifilter rotating shadowband radiometers (MFRSR) and solar infrared radiation stations (SIRS) gather information about downwelling, upwelling, direct, and diffuse irradiances at these sites. Measurements of soil temperature and water status will be gathered by the soil water and temperature system (SWATS), while an infrared thermometer (IRT) provides measurements of the equivalent blackbody brightness temperature of the scene in its field of view.

To ‘ground truth’ other remote-sensing equipment, the Surface Meteorological Observation System (SMOS) is a collection of sensors that obtain 1-minute, 30-minute, and 1440-minute (daily) averages of surface wind speed, wind direction, air temperature, relative humidity, barometric pressure, and precipitation. As part of an international network of global positioning systems (GPS) called SuomiNet, GPS receivers generate near real-time estimates of precipitable water vapor in the atmosphere, total electron content in the ionosphere, and other meteorological and geographical information. These measurements round out the data obtained at the SGP extended facilities.

In addition to Anthony (Kans.) and Marshall (Okla.), new SGP extended facility sites are located near Medford, Newkirk, Tryon, Waukomis, and Omega in Oklahoma; and Maple City in Kansas. They join seven other sites, some of which have been operating since 1993, for a total of 15 extended facilities.