Flux-Gradient Technique with Ammer Valley Surface Layer Measurement Network

Three sites in the Ammer Valley, in Baden-Württemberg (southwest Germany), have newly installed ground stations. The Ammer Valley is in the complex terrain between the Black Forest and Swabian Alb, and it is characterized by high land-use heterogeneity. Within the 240 sq.km valley, station sites were selected for geographic, soil, and plant diversity. These stations were designed for a flux-gradient approach to measuring surface layer momentum, heat, and moisture fluxes. Using the flux-gradient method, estimated surface layer fluxes will be compared to an eddy covariance system, which is collocated with one of the flux-gradient stations. One motivation for investigating a flux-gradient measurements is the high cost of an eddy covariance system. With two heights and using 2-dimensional sonic anemometers, a flux-gradient station is approximately an order of magnitude less expensive than an eddy covariance system. Besides instruments for flux-gradient measurements, each site has a net radiometer, soil heat flux plates, and sub-surface temperature and moisture sensors up to 1.5 m deep, all of which provide additional measurements for surface fluxes. Three stations were setup during the winter of 2013-2014, and two additional stations will be setup in 2014. This project also provides the basis for collaborative research in atmospheric, soil, and plant interactions.