The EGER 2007 Micrometeorological Experiment in the Fichtelgebirge Mountains, Germany

The EGER (ExchanGE processes in mountainous Regions) project aims at the detailed quantification of relevant processes within the soil-vegetation-atmosphere system by observing diurnal and annual cycles of energy, water and trace gases. The main focus lies on the understanding of process interactions among different scales and their role for corresponding budgets. Field experiments were carried out at the Waldstein site in the Fichtelgebirge mountains (a low mountain range typical for central Europe), which are challenging for their heterogeneity and orographically structured terrain. Field observations are complemeted by model simulations. Even though the EGER joint effort combines biogeochemical, chemical and micrometeorological subprojects, this work addresses the mircrometeorological part only.

Micrometeorological measurements were conducted within the first intensive observation period at the Waldstein site in September and October 2007. The turbulence structure within and above the forest was observed with eddy covariance systems mounted at several levels on a 35 m high tower, covering the trunk and the crown space as well as the roughness sublayer above the canopy. To monitor horizontal advection as well as catabatic flows several small masts were set up in the trunk space of the forest and equipped with sonic anemometers, humidity and temperature sensors as well as CO2 analyzers. A SODAR-RASS system setup at a nearby clearing provided local boundary layer information. The long term observing programme at the Waldstein site supplied meteorological data for in- and above canopy profiles of wind, temperature and humidity as well as for radiation and soil temperature and moisture.

The obtained data set allows the detailed investigation of advection, turbulence structure (coherent structures) and flux gradients of meteorological quantities within and above the forest. In addition, it is a good opportunity (a) to apply a higher order closure model (ACASA, third order), and (b) to test its ability to reproduce the turbulence structure and to reflect the exchange regimes within and above the forest. Our contribution will present an overview of the setup of the experiment as well as first experimental and model results.