PhD Thesis

Improving our understanding of the atmospheric weak wind boundary layer using spatially explicit observations near the ground surface

Lena Pfister (03/2016-09/2019)

Support: Christoph Thomas

I am using the Distributed Tempersture Sensing (DTS) technique to investigate nocturnal weak wind situations in gentle terrain. For my master thesis 'Novel insights into the dynamics of cold-air drainage and pooling on a gentle slope from fiber-optic distributed temperature sensing', supervised by Prof. Dr. Christoph Thomas, I worked the first time with the DTS-technique. The results showing that temperature behavior, but not flow dynamics can be predicted by microtopographic analysis will soon be published in Boundary-Layer Meteorology. I worked together with Armin Sigmund on this project, who already published a paper about the used supporting structure for the glass-fiber and associated radiation errors in Atmospheric Measurement Techniques Discussions.

Right now I am analyzing the Shallow Cold Pool (SCP) experiment near Wellington in Colorado (USA) from 2012. The aim of this study was to investigate the formation and maintenance of common shallow cold pools during September, October and November. This field project consisted of an extensive network of sonic anemometer, pressure, temperature, moisture and CO2 sensors. Ancilliary a SODAR was empolyed and a fiber-optic DTS-network. The DTS-network was a cross transect of the local gentle slope and measured downslope wind speeds as well as temperatures with a spatial and temporal resolution of 0.125 m and 5 s. I want to stratify my data into four different nocturnal scenarios and investigate the horizontal and vertical temperature behaviour as well as flow dynamics and interactions/relations between both.

First analysis showed distinct temperature patterns (red arrows), which will also be investigated.

After this study I will work together with Prof. Dr. Christoph Thomas and the team on the ERC DarkMix project .