EDDY CORR. SURFACE FLUX: UK (FIFE)

Surface flux measurements were made at selected sites within the FIFE study area. Each surface flux station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat. The Eddy Correlation Surface Flux Observations (UK) Data Set contains surface flux and micrometeorological measurements collected from one location in the southwest quadrant of the FIFE study area. This location was grazed and had a gentle downhill slope to the southwest. Data were collected daily from May 14 - October 18, 1987, and from July 21 - August 16, 1989. The output from the Hydra sensors is sampled at 10 Hz and processed in real time to give hourly averages of sensible and latent heat flux and the friction velocity. The hourly mean values of net radiation, temperature, and of vapor pressure, provided in this data are a synthesis of the best measurements available for this site. The temperature measurement provided here is the preferred value for this site. This temperature was used to calculate the fluxes and some standard deviations. This is necessary because the sonic anemometer has a slightly temperature dependent calibration. The average soil heat flux measured at 5 mm depth is a weighted average value over three sample positions with dense, medium and sparse vegetation. A vegetation survey was made to assign weights to these three classes at this site. The spatial variability in this measurement at this (over) grazed site is particularly high and the three individual sensors commonly measure soil heat fluxes differing by factors of two or three. Some evidence suggests these data are providing a measurement of this component of the energy budget for this site which is biased low. Presumably this is because the limited number of sensors inadequately samples the points with low canopy density for this sparse crop cover.