Advancing Toward Gray Zone: Evaluation of Tropical Cyclones in Key Basins With the 12.5 km High Resolution CAS FGOALS‐f3 Model

Abstract

State‐of‐the‐art climate models are approaching gray‐zone resolutions that can improve the representation of tropical cyclones (TCs), but the extent of these gains remains uncertain. This study evaluates the effect of spatial resolution, particularly near the gray‐zone, using three resolution configurations of the Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System Finite‐Volume version 3 (CAS FGOALS‐f3) climate model: f3‐L (standard, ∼100 km), f3‐H (high, ∼25 km), and f3‐HH (ultra‐high, ∼12.5 km), focusing on TC genesis, track, intensity, and structure. All three configurations employ the scale‐aware Resolving Convective Precipitation (RCP) parameterization with common key parameters, enabling a controlled assessment of resolution‐dependent behavior within a consistent physics framework. Simulations are assessed against the International Best Track Archive for Climate Stewardship Version 4 (IBTrACS‐v4) data set from 1998 to 2007, using two observational baselines to address inter‐agency discrepancies. Results indicate that increasing resolution enhances maximum wind speed, minimum central pressure, and storm structure, enabling more realistic representation of high‐category storms up to Category 3, particularly in the Western North Pacific and North Atlantic. Higher‐resolution versions also show improved spatial distribution of TC genesis and track frequency when evaluated globally. While all model versions capture the seasonal cycle of TC counts globally and across basins, they exhibit limitations in accurately simulating Category 4–5 storms and capturing interannual variability. These results highlight both the benefits and remaining limitations of high‐resolution, scale‐aware global climate simulations for representing TC behavior at gray‐zone resolutions.