Representation of West African mesoscale convective systems in NextGEMS km-scale simulations

Mesoscale convective systems are a crucial feature in Sahel, a water vulnerable semi-arid region in West Africa. Observational studies have shown that they are responsible for bringing approximately 90% of the rainfall during the summer monsoon season, and play an especially important role in extreme rainfall events. Despite of their important impacts on society and climate, traditional general circulation models, with their coarse horizontal resolution and parameterized convection schemes, struggle to properly simulate these organized convective systems. However, the newer generation of km-scale convection-permitting climate models have been shown to much more accurately capture the characteristics of mesoscale convective systems, showing great potential for studies of future climate change in vulnerable regions such as the Sahel.

In this study we analyze the latest simulations run with IFS and ICON within the NextGEMS project, with a horizontal resolution up to 9 km. Using a lagrangian tracking algorithm to identify the mesoscale convective systems, we investigate how they and their related weather are represented in the models, how well they scale in strength with known amplifying factors and if any trends can be identified in the simulation.