Greenhouse Gases (GHGs)
Analysis of GHG concentration and flux measurements
We work on the analysis of Greenhouse Gas (GHG) concentration and (Eddy Covariance) flux measurements at a Swiss tall tower site. Most flux towers provide observations at heights of several meters to tens of meters and therefore provide information about possible flux sources on a local spatial scale. Here we focus on one of the few European tall towers located close to Beromünster, Switzerland. The tower was initially set up as a CarboCount CH site — a dense GHG observation network run for four years (2012 - 2015) — and is continued since by the University of Bern. The highest measurements are taken at an altitude of 212 m above ground. This relatively high observation height results in a a flux footprint (field of view) of the tower of many kilometers, making its observations predestined to a source analysis on a much larger spatial scale than typical for flux towers. On the one hand, we use a flux footprint parameterization to estimate where the measured fluxes originate. Additionally, we analyse GHG concentration measurements by season, time of day, wind direction, and other criteria and perform various correlation analyses. In future work, the FLEXPART model will be used to further investigate the origin of the measured pollutants. This work is done in a close collaboration with the University of Bern.
This figure shows the annual mean flux footprint for the Beromünster tall tower close to Zurich, Switzerland. Isolines indicate the percentage of where observed Eddy Covariane fluxes originate, e.g., 80% of the fluxes originate within the area enclosed by the 80 % contour. © Andreas Plach
The scatter plot shows the strong correlation between oberseved CO2 and CO concentrations at the Beromünster site during the winter months (December, Janurary, February). The concentrations are expressed as deviations from the seasonal mean (mean calculated for each hour of each month). © Andreas Plach