New high-resolution climate simulation ensembles highlight the importance of mesoscale dynamics in shaping future extreme precipitation

A new study by Chang et al. (2025) using unprecedented high-resolution global climate simulation ensembles highlights major advances in representing mesoscale convective systems (MCSs) over global land and provides fresh insight into their role in driving future extreme precipitation changes. These simulation ensembles – produced at 10-25 kilometer resolution – are part of a collaborative modeling effort that enables robust assessment of mesoscale processes previously inaccessible to standard 100-kilometer low-resolution global models. This work was primarily supported by the MESACLIP (Understanding the Role of MESoscale Atmosphere-Ocean Interactions in Seasonal-to-Decadal CLImate Prediction) project, funded by the US National Science Foundation (NSF).

The global high-resolution climate simulations demonstrate a major leap forward in capturing the spatial and temporal structure, as well as rainfall characteristics of present-day MCSs. Compared to traditional ~100-kilometer models, finer-resolution simulations produce more realistic MCSs with significantly stronger associated extreme precipitation. This enhanced realism provides a strong physical basis for evaluating how MCS behavior may evolve in a warmer climate.

A central result is that future intensification of MCSs plays a dominant role in amplifying extreme precipitation over global land. In the high-resolution ensembles, MCSs strengthen under warmer conditions, and these dynamical changes account for a substantial fraction of the projected increase in extreme daily rainfall – far beyond what would be expected from thermodynamic arguments alone. In contrast, coarse-resolution models substantially underestimate these MCS-driven changes. Their inability to represent multiscale interactions of atmospheric phenomena leads to muted moisture convergence, and an underestimation of both present-day extremes and their projected future intensification.

This study highlights one example of the multifaceted scientific value of the new high-resolution ensembles. By improving the representation of key mesoscale processes that govern extreme rainfall, the new ensembles open a pathway to more physically grounded understanding of precipitation extremes, seasonal-to-decadal predictability, and atmosphere-ocean interactions. To support broad community use, all the high-resolution simulation datasets have been publicly released and are available through the NSF NCAR Geoscience Data Exchange (GDEX) on the MESACLIP project page: https://project.cgd.ucar.edu/projects/MESACLIP.

As global modeling centers advance toward finer resolutions, coordinated high-resolution ensembles such as this will play a critical role in improving confidence in future hydrological projections and uncovering the dynamical processes that shape Earth’s most intense storms.