Quantifying the Carbon Footprint of Paris with LIDAR Remote Sensing Observations in the Boundary Layer

Understanding the complex temporally and spatially varying carbon dioxide (CO2) emissions in urbanized areas is crucial to identifying causes of climate change and how they can be addressed. While many studies have been conducted to better quantify urban CO2 (and other pollutant) fluxes, there are still many open questions about the interpretation of these measurements and how emissions scale with population, as well as how to attribute concentrations measured in urban environments to anthropogenic and natural sources and sinks. After deployment for six months (November 2015-April 2016) in Paris, France, data from the Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE^™), an observing system that combines laser-based differential absorption spectroscopy measurements with tomographic techniques to create a two dimensional map of CO2 concentrations, was interpreted and analyzed. An evolution equation for CO2 mixing ratio within the Planetary Boundary Layer (PBL) was applied to identify and separate sources and sinks of CO2. Results from this analysis directly verify the impacts that wind speed and direction have on CO2, namely dilution and enhancement. Preliminary analysis characterized the relationships between CO2 and nitrogen dioxide (NO2) and ozone (O3). GreenLITE™ proves to be an accurate measuring tool for CO₂, but further interpretation and analysis of data is necessary to estimate the emissions of Paris. Further investigation will include examining solar radiation and cloud cover, along with continued analysis regarding other pollutants mentioned and introducing methane. The entire time period will also be examined.