Comparative Analysis of the ALARO Regional Atmospheric Model for Extreme Precipitation Across Multiple Tropical Domains.

This study conducts a detailed analysis of the ALARO regional weather and climate model, focusing on its ability to simulate extreme tropical precipitation across three distinct tropical regions. Utilizing data from three contrasting domains—the Amazon Basin in South America, the Lake Victoria region in East Africa, and Darwin in northern Australia—we evaluate the model's performance in diverse tropical settings: continental rainforest, continental highland lakes, and maritime tropical environments. The analysis draws upon US Department of Energy Atmospheric Radiation Measurement (ARM) facility datasets from Darwin and the Amazon, extensive sub-daily rain gauge networks across the Lake Victoria basin, and complementary satellite observations to evaluate precipitation characteristics across multiple scales. Beyond surface rainfall patterns, we compare atmospheric microphysical properties including droplet size distributions, hydrometeor content, and convective structures through vertical velocity analysis. By leveraging these comprehensive observational datasets, our study conducts for the first time a detailed evaluation of ALARO's convection-permitting capabilities in these challenging tropical environments. We simulate each domain over two-year periods at 4-km resolution to establish robust precipitation statistics, with additional high-resolution 1-km runs targeting intensive observation periods from ARM field campaigns to assess fine-scale convective dynamics. Multiple physics configurations are evaluated across both resolutions to assess model sensitivity. The results provide valuable insights into ALARO's strengths and limitations for tropical precipitation simulation, highlighting critical needs for model development in regions where extreme rainfall significantly impacts local communities.