Simulation of Greenhouse Gases in the Atmosphere (Vardag - Group) Research

Greenhouse gas concentrations in the atmosphere are shaped by the interplay of emissions, uptake processes, and meteorological transport. To understand where greenhouse gases come from, how they move, and how strongly different sources and sinks contribute, we combine atmospheric measurements with atmospheric transport models and inverse estimation methods. 

Our modelling approaches cover a wide range of spatial scales. In cities, high-resolution models resolve airflow around buildings and within street canyons, allowing us to simulate concentration enhancements from urban emissions. At regional scales, meteorological models are used to study transport over complex landscapes and to identify the source regions influencing individual measurement sites. At continental to global scales, coarser atmospheric models help quantify large-scale biogenic fluxes and compare observation-based estimates with process-based ecosystem models.

Depending on the scientific question, we use both Eulerian models, which simulate concentration fields on a fixed grid, and Lagrangian models, which follow air masses backward or forward in time. These models provide the link between observed greenhouse gas concentrations and the surface fluxes that caused them.

To quantify emissions and fluxes, we apply inverse modelling techniques. These methods combine observations, transport simulations, prior emission estimates, and uncertainty information to infer the most likely distribution of greenhouse gas sources and sinks.

The resulting emission estimates provide independent constraints on natural and anthropogenic greenhouse gas fluxes. They can support the independent evaluation of emission inventories, contribute to transparent monitoring of climate-relevant emissions and, improve our understanding of biospheric carbon-cycle processes.