Latent & sensible heat flux by eddy correlation & aerodynamic characterization of vegetation

FIFE observations of surface fluxes

Surface flux measurements by eddy correlation technique during FIFE

The Eddy Correlation Surface Flux Observations (Argonne) Data Set contains surface flux measurements made at selected sites within the FIFE study area. The surface area and aerological data described here were located at 2 sites in the northwest quadrant of the study area within the Konza Prairie Natural Research area. Both sites were located on hill tops that were burnt on a regular cycle. These data were collected daily only during the five Intensive Field Campaigns which were held during the growing season of 1987 and the projected summer dry down in 1989. Data were also collected using a portable eddy correlation system that moved to a variety of locations within the FIFE study area. These data were collected for a day or two at each location sometime between June 1, 1987 and October 13, 1987. Argonne National Laboratory did not measure radiation but concentrated on observations of turbulence quantities, primarily covariances and standard deviations of winds, temperature, water vapor, and other quantities. The surface fluxes and standard deviations of carbon dioxide and ozone were measured by Argonne so that the fluxes of mass could be related to each other, surface biophysical conditions, vegetative parameters, and the optical characteristics of the surface that could be detected by remote sensing.

Areal average evapotranspiration by measuring & modeling surface controls

Surface flux and micrometeorological measurements were collected at one site within the northwest quadrant near the center of the FIFE study area during all five of the Intensive Field Campaigns (four in 1987 and one in 1989). This site had historically been ungrazed but had recently been exposed to grazing. The station was capable of measuring the fluxes of net radiation, sensible heat and latent heat using an eddy correlation system. In addition, measurements of soil heat flux and several micrometeorological parameters were made.

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.

The Eddy Correlations Surface Flux Observations (GSFC) Data Set contains surface flux measurements made at selected sites within the FIFE study area. The surface flux and micrometeorological measurements in this data set were collected from a single location located in the southwest quadrant on a upland, grazed area. The data set contains data collected daily from June 26 - October 17, 1987 during the three Intensive Field Campaigns. No data is available between the campaigns. Micrometeorological techniques of eddy correlation and Bowen ratio were used in determining the fluxes of sensible heat, latent heat, and carbon dioxide in FIFE. Eddy correlation is a well-established technique that has the primary advantage of measuring turbulent diffusive fluxes directly across a near-horizontal plane above the surface. It requires a rigid platform unencumbered by significant aerodynamic obstacles. The fluxes of sensible and latent heat are computed as covariances of the fluctuations of vertical wind velocity with fluctuations of temperature and vapor density at the same point and time.

Surface flux measurements were made at selected sites within the FIFE area. Each surface flux station was capable of measuring the fluxes of net radiation, sensible heat, and latent heat. The data contained in the Eddy Correlation Surface Flux Observations (USGS) Data Set were collected from two sites located in the northwest and southwest quadrants on slight inclines in the FIFE study area. These data are available only during the four Intensive Field Campaigns, held during the growing season of 1987, May 25 - October 17. During this period there are 66 days of data.

This dataset includes the following measurements made over a managed lawn at Fort Logan Cemetery in Denver Colorado in 2011 and 2012. (No measurements were made in winter months: December, January, February). 1) half hourly eddy covariance measurements of evapotranspiration and fluxes of carbon dioxide and sensible heat 2) half hour averages of solar and net radiation, air temperature and humidity, soil temperature, moisture, and heat flux, and half hour sums of precipitation. 3) approximately weekly measurements of vegetation: leaf area index, height of vegetation, dry and wet weights