University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Mirjam Kreisel
(2019):
Measuring the Albedo of Lichens
TOWARDS AN OPTIMIZED EXPERIMENTAL SETUP WITH THE KIPP AND ZONEN NET RADIOMETER CNR4.
Master / Diploma Thesis - Institut für Meteorologie und Klimatologie,
BOKU-Universität für Bodenkultur,
pp 70.
UB BOKU
obvsg
- Abstract:
- In this thesis, the reader gets introduced to the importance of lichens in alpine areas and their influence on the microclimate is discussed. Climate change affects this sensitive vegetation and decreases the abundance of lichens, which has an impact on the microclimate. One focus of this thesis was to figure out the ideal setup for the net radiometer CNR4 in mountainous terrain, in order to perform measurements of the albedo of lichens mats. Therefore, the impact of the height of the net radiometer, the length of the rod, different mounting systems and the solar zenith angle, as well as first measurements of prepared lichen pads were systematically tested. Various measurements of the albedo of lichen vegetation, a black surface, a snow surface, or a combination of the black and snow surface have been carried out. Results gave an indication that the empirically ascertained radius of the radiometer corresponds with the theoretically calculated radius. This led to the conclusion that the optimal height of the sensor can be estimated based on the relationship between the selected surface area and radius. Furthermore, a rod length of 0.3 m is seen as ideal since no influence of the rod was noted in the results. It is expected that the stability of a relatively shorter rod is higher than with a longer rod length. Another finding was that the albedo of the lichen species Cladonia stellaris, Cladonia rangiferina, Flavocetraria nivalis averages between 0.32±0.01– 0.33±0.02. Moreover, it got displayed, that the solar zenith angle is influencing the measurements, especially on snow properties. It was shown, that the net radiometer CNR4 is a convenient device. However, it is important to mount it on a stable system, which in this thesis appeared to be a steel pole dug into the soil, combined with an aluminum rod.
- Beurteilende(r): Weihs Philipp