NCAR/CU surface, soil, and vegetation observations during the International H₂O Project 2002 field campaign

The May-June 2002 International H₂O Project was held in the U.S. Southern Great Plains to determine ways that moisture data could be collected and utilized in numerical forecast models most effectively. We describe the surface and boundary layer components, and indicate how the data can be acquired. These data document the eddy transport of heat and water vapor from the surface to the atmosphere (in terms of sensible heat flux H and latent heat flux LE), as well as radiative, atmospheric, soil, and vegetative factors that affect it, so that the moisture and heat supply to the atmosphere can be related to surface properties both for observational studies and tests of land surface models. The surface dataset was collected at 10 surface flux towers at locations representing the major types of land cover and extending from southeast Kansas to the Oklahoma Panhandle. At each location, the components of the surface energy budget (H, LE, net radiation, and soil heat flux) are documented each half-hour, along with the weather (wind, temperature, mixing ratio, air pressure, and precipitation), soil temperature, moisture, and matric potential down to 70-90 cm beneath the surface at 9 of the 10 sites. Observations of soil and vegetation properties and their horizontal changes were taken near all 10 towers during periodic visits. Aircraft measurements of H and LE from repeated low-level flight tracks along three tracks collocated with the surface sites extend the flux tower measurements horizontally. We illustrate the effects of vegetation and soil moisture on the H and LE and their horizontal variability.