EBEX: Energy Balance Experiment, 2000

Summary

The Energy Balance Experiment (EBEX-2000) studied the ability of state-of-the-art measurements to close the surface energy balance over a surface (a vegetative canopy with large evapotranspiration) where closure has been difficult to obtain. A flood-irrigated cotton field over uniform terrain was used, though aerial imagery and direct flux measurements showed that the surface still was inhomogeneous. All major terms of the surface energy balance were measured at nine sites to characterize the spatial variability across the field. 

EBEX addressed why measurements often cannot achieve closure by:

1. Studying a surface for which energy balance closure has been difficult to obtain, but still relatively easy to instrument - a closed canopy with high evapotranspiration.

2. Measuring all terms of the energy budget directly at comparable scales. In particular, deploying enough sensors to create an average of each term over an area large enough to encompass several flux “footprints”.

3. Performing side-by-side intercomparisons of instruments from different manufacturers.

4. Comparing processing methods of different research groups, including filtering and flow distortion corrections in the eddy-covariance measurements, using a reference dataset.

In addition, temperature and wind profiles were measured at three locations to provide information on site homogeneity - in particular the presence or lack of internal boundary layers over the site. 

More information can be found in following article:

Oncley, S.P., Foken, T., Vogt, R. et al. The Energy Balance Experiment EBEX-2000. Part I: overview and energy balance. Boundary-Layer Meteorol (2007) 123: 1. doi:10.1007/s10546-007-9161-1