Uni-Bayreuth

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Lukas Pauscher: Theses supervised

Master's Theses

Sebastian Varga (2015) Einfluss der Mischungsschichthöhe auf dasWindprofil über einem bewaldeten Standort

This master thesis aims to measure the influence of the top of the mixed layer on a hilly forest site. To do this, the top of the mixed layer that was determined with a ceilometer by the software installed in the device and in turn compared with a top of the mixed layer that was made with the slab model. In order to model the windprofile, simple methods (logarithmic windprofile, Power Law) were compared to complex methods which use the top of the mixed layer (Windprofiles from Gryning et al. (2007); Peña et al. (2009b)). However, because of the heterogeneity of the area it was necessary that the roughness was determined in an alternative way that has been not used before and to determine the top of the mixed layer with the method of Peña et al. (2009b). In order to eliminate the anomalies, which occurred in the measured top of the mixed layer the so called cloud correction was developed. The top of the mixed layer that was determined by a ceilometer’s interal software can be corrected with it.To do this, the cloudiness was determined with a Pyranometer and, with the anomalies in the ceilometer’s measurement, detected and finally corrected. The top of the mixed layer that was modelled after the Slab-model shows good quality. The quality of the measured top of the mixed layer could improved by cloud correction. The evaluation shows that the best model quality at day and at night (here the quality is always bad) can be achieved by the power law with the exponents 1/7. I conclude that can there is no relevant influence of the top of the mixed layer on the wind profiles.

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Supervisor: Thomas Foken, Lukas Pauscher