Dynamics of temperature and wind profile in the boundary layer of a valley in the Fichtelgebirge Mountains
Elena Loos (01/2016-12/2016)
Support: Christoph Thomas
The atmospheric boundary layer is an important part of the atmosphere. In this 100 to 3000 m thick layer the atmosphere is affected by the surface of the earth. Processes in this part of the atmosphere such as the spreading of pollutants, the transfer of heat from the surface upwards or the transport of water vapor produced by transpiration and evaporation influence our lives importantly. This is why the understanding of these processes is crucial . In complex terrain there are additional processes such as up - valley and down - valley winds that occur due to slopes. The experiment “WOBLS” (Wind Observation in the Boundary Layer at the Schneeberg) aims at the better und erstanding of the wind flow and temperature distribution in the atmospheric boundary layer. During a period of 40 days, wind direction and wind speed were measured by a SODAR (SOund Detection and Ranging instrument) at the top of the Schneeberg in the Fichtelgebirge Mountains and wind direction, wind speed, potential temperature and the reflectivity of the antennas were measured by a SODAR RASS ( SOund Detection and Ranging instrument with Radio Acoustic Sounding System extension) at the bottom of the Schneeberg near the village Voitsumra . The measurements of the station at the bottom of every night and every day were used to identify different flow regimes in the area of the Schneeberg. It was expected that the formation of a nightly inversion can be detected. Furthermore, the existence of low - level jets and cold air flow in combination with the development of cold air pools was expected. In addition it was planned to compare wind direction and wind speed of the station at the bottom and the summit - station. It was found out that the main wind direction in this region is West. With low wind speeds there can be a change of wind direction with height from East at the bottom to South in a height of about 200 m agl . The stratification during most nights was stable, an inversion was detected in some of them. A low - level jet was observed in some nights, too. For cold air flows, the measuring range started too high, therefore a cold air flow could not be detected soundly. The maximum observational height was surprisingly low and the measuring ranges of the two stations did not overlap so a comparison was not made.