Updating existing emission data
The researchers began with an emission map from the Dutch research institute TNO. It provides a spatial representation of greenhouse gas emissions in Hamburg, based on national reported emissions that have been spatially distributed using proxy data (population density map, etc.). To check and update the values shown on the map, the team selected two approaches:
“First, we conducted mobile measurements using a car equipped with sensors. We drove it through areas, where we expected to detect methane emissions, to gain a better understanding of the spatial distribution. Second, we used our sensor network to measure the overall emissions in the city. The network is made up of four measurement devices, which we used in previous studies to measure emissions in Munich,” says Jia Chen, Professor of Environmental Sensing and Modeling at TUM. “Our sensor network uses the sun as a light source. Because every molecule in the atmosphere absorbs only specific frequencies of the sunlight, we can determine the concentrations of the various greenhouse gases in the column of air between our measurement device and the sun.”
