- 1UK Centre for Ecology and Hydrology, Hydro-climate Risks, Wallingford, United Kingdom of Great Britain – England, Scotland, Wales (emmbar@ceh.ac.uk)
- 2National Centre for Earth Observation, Wallingford, UK
- 3School of Earth and Environment, University of Leeds, Leeds, UK
- 4National Centre for Atmospheric Science, Leeds, UK
- 5NORCE Norwegian Research Centre AS, Bergen, Norway
- 6Atmospheric, Climate, and Earth Sciences, Pacific Northwest National Laboratory, Richland, WA, USA
- 7Max Planck Institute for Meteorology, Hamburg, Germany
Mesoscale convective systems (MCSs) are large, organised storms that threaten communities in multiple regions around the world with extreme rainfall, lightning and strong winds that can lead to flooding, mudslides, destruction of property and loss of life. Improving predictability of these storms is vital for reducing their impact on the population and requires understanding of processes that favour their growth.
Our recent observation-based analysis of thousands of MCSs across seven storm “hot-spots” (West Africa, South Africa, India, China, South America, Great Plains and Australia) revealed a new mechanism of storm enhancement by mesoscale (~500 km) soil moisture gradients via vertical wind shear, a key ingredient for MCS growth. Specifically, a 10-30% increase in extreme (90th percentile) precipitation feature size and rainfall was observed on days with favourable surface conditions, compared to days with unfavourable conditions.
In the current work we exploit multidecadal global convection permitting high-resolution (10 km) ICON simulation to analyse surface driven MCS enhancement under climate change. For the seven regions considered in the observational analysis, in ICON we find precipitating mature storms to be favoured in the vicinity of mesoscale soil moisture gradients and a strong relationship between vertical wind shear and storm size and rainfall, consistent with the observations. For an SSP370 type scenario (7 W/m² forcing by the year 2100) we show the impact of changing surface conditions on MCS enhancement linked to our identified mechanism.
How to cite: Barton, E., Klein, C., Taylor, C., Marsham, J., Parker, D., Maybee, B., Feng, Z., Leung, L. R., and Hohenegger, C.: Strengthening of Mesoscale Convective Systems by Soil Moisture Gradients in ICON , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5932, https://doi.org/10.5194/egusphere-egu25-5932, 2025.
