Extreme Precipitation in High-Resolution and Convection-Permitting Earth System Models

As the climate system warms, precipitation is expected to become more intensity due to an increase in specific humidity and enhanced convective uplift of low-level moisture. However, extreme precipitation events can span a range of scales from 10s to 10,000s of kilometers (i.e., from mesoscale convective systems to atmospheric rivers) and representing the small- and large-scale processes that govern these events has been a limitation in future projections from conventional Earth system models. Two promising methods have shown improvements in some aspects of precipitation intensity by better resolving the convective-scale processes or the large-scale dynamics of these events with superparameterization (i.e., embedded cloud-resolving models in place of convective parameterizations) and high-resolution (i.e., ~25 km horizontal grid-spacing), respectively. Both methods are often compared to conventional low-resolution simulations at a common ~100 km scale, but are not compared to each other directly. In this study, changes in the statistics of precipitation are compared across all three versions (i.e., low-resolution, high-resolution, and super-parameterization) at a common scale and at scales that are sub-grid to the low-resolution version (i.e., spatial variability across internal cloud-resolving model columns and the high-resolution grid), which can be particularly important for flood impacts.