canceled
Investigation of turbulent structures at a forest edge
2 Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Garmisch-Partenkirchen, Germany
3 Inorganic and Isotope Geochemistry, German Research Centre for Geosciences (GFZ), Potsdam, Germany
O 2.2 in Research in its Prime: First Results of Ongoing Research
10.10.2013, 09:30-09:45, H6, GEO
To investigate the impact of a forest edge on exchange processes in the soil-vegetation-atmosphere-boundary-layer-system within a heterogeneous forest ecosystem was the main objective of the EGER IOP3 project (ExchanGE processes in mountainous Regions, Intensive Observation Period 3). This included turbulent flux measurements by the eddy covariance technique, as well as gradients by a Horizontal Mobile Measuring System (HMMS) along a forest-to-clearing transition, conducted in summer 2011 at the BayCEER research site in the Fichtelgebirge.
The HMMS reveals strong gradients at the forest edge, which indicates a horizontally non-homogeneous distribution of turbulent structures. This can also be found in classified exchange regimes (coupling), determined by the distribution of well-organised turbulent motions (coherent structures, CS). Because this distribution is not caused by differences in wind direction, it can be assumed that thermal and roughness differences between clearing and forest trigger large circulations located above the clearing. These large circulations above the clearing induce additional vertical motions directly at the forest edge, where propagation of CS in the vertical direction is enhanced and causing better ventilation at the forest edge. At daytime we found a systematic outflow (ejections) and at nighttime an inflow of fresh air (sweeps).
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