Zoning Evaluation of Hourly Precipitation in High-resolution Regional Numerical Models over Hainan Island

This study assesses the performance of three high-resolution regional numerical models in predicting hourly rainfall over Hainan Island from April to October for the years from 2020 to 2022. The rainfall amount, frequency, intensity, duration, and diurnal cycle are examined through zoning evaluation. The results show that the China Meteorological Administration Guangdong Rapid Update Assimilation Numerical Forecast System (CMA-GD) tends to forecast a higher occurrence of light precipitation. It underestimates the late afternoon precipitation and the occurrence of short duration events. The China Meteorological Administration Shanghai Numerical Forecast Model System (CMA-SH9) reproduces excessive precipitation at a higher frequency and intensity throughout the island. It overestimates rainfall during the late afternoon and midnight periods. The simulated most frequent peak times of rainfall in CMA-SH9 are 0-1 hour deviations from the observed data. The China Meteorological Administration Mesoscale Weather Numerical Forecasting System (CMA-MESO) displays a similar pattern to rainfall observations but fails to replicate reasonable structure and diurnal variation of frequency-intensity. It underestimates the occurrence of long-duration events and overestimates related rainfall amounts from midnight to early morning. Notably, significant discrepancies are observed in the predictions of the three models for areas with complex terrain, such as the central, southeastern, and southwestern regions of Hainan Island.