Master Thesis Defense by Gustav Stolberg-Larsen

Title: Prospects of Atmospheric Sounding and Inverse Modelling of CO2M Satellite Data

The monitoring of greenhouse gasses from space is a crucial tool for mitigating the impact of anthropogenic greenhouse gas emissions on the climate. In coming years, satellite monitoring is going to assist in validating and quantifying hot-spot point source emissions of industry, mega-cities, and power plants. In 2026 ESA, The European Commission, European Copernicus program, and EUMETSAT will launch the CO2M mission satellite into sun-synchronous orbit.
The new satellite, with a unprecedented precision of >0.7ppm on CO2 sounding measurements and swath-width of 200 km, advances the older OCO2 satellite from 2014, with precision of >2ppm and a swath-width of maximum 10 km. Together with high-resolution detection of clouds and aerosols, the CO2M satellite measures NO2 in the visible spectrum. The short-lived auxiliary reactive gas can be used as a tracer of anthropogenic greenhouse gas emission rates.
A literature review is conducted on the ongoing research of using inverse modelling methods to quantify CO2 emission rates using concurrent co-located NO2 data. The following methods are presented: 1) Naive NO2 to CO2 ratio approach, 2) Cross Sectional Flux method, 3) Gaussian Plume Inversion, 4) Maximum Likelihood Estimation, 5) Convolutional Neural Network. Additionally, the Cross Sectional Flux method is deduced and applied for calculating the mass flow rate of co-located NO2 and CO2 measurements. Data is obtained from the OCO2 satellite measuring CO2, sentinel-5 precursor satellite TROPOMI instrument measuring NO2, and ERA5 data of cloud cover and wind conditions. Results from 5 cases of pre-selected locations are replicated independently. The cases are chosen from an article by Reuter et. al. in 2019. No disagreement with the findings, within the uncertainties of each case was found.

Supervisor: Jens Hesselbjerg Christensen