Scale-aware representation of aerosol activation and cloud droplet condensation processes to improve microphysical consistency across model resolutions

Regarding the uncertainty in the simulation performance of microphysical schemes across horizontal resolutions, this study employs idealized supercell thunderstorm experiments using the WRF model. We analyze the sensitivity of key microphysical processes in the Morrison microphysics scheme at different horizontal resolutions (3, 1, 0.5 km), and investigate horizontal scale-aware methods for aerosol activation and cloud droplet condensation. The results show that several microphysical processes exhibit strong sensitivity to horizontal resolution, particularly aerosol activation and cloud droplet condensation, which are crucial for liquid-phase cloud formation. To enhance the consistency of the microphysical scheme’s representation across different horizontal resolutions, a normal distribution function for variables such as vertical velocity is applied to coarser-resolution grids based on high-resolution simulation results, thereby explicitly describe the non-uniform distribution of variables within the grid. Compared to high-resolution (0.5 km) simulation results, incorporating the binned normal distribution function of vertical velocity into the aerosol activation process reduced the discrepancy in the average cloud droplet number concentration by 72.73% (0.16 × 10 6 kg −1 ) at 1 km resolution and by 90.63% (0.58 × 10 6 kg −1 ) at 3 km resolution. Similarly, incorporating the binned normal distribution function of supersaturation into the cloud droplet condensation process reduced the difference in the average conversion rate of cloud droplet condensation by 18.18% (0.04 × 10 −6 kg kg −1 min −1 ) at 1 km resolution, and by 29.31% (0.34 × 10 −6 kg kg −1 min −1 ) at 3 km resolution. The results indicate that considering the sub-grid distribution of vertical velocity and supersaturation in the microphysical scheme can effectively reduce cross-resolution simulation differences and enhance the dynamic adaptation capability of the microphysical scheme to different horizontal resolutions.