热带气象学报2026，Vol.42Issue(4)：540-554,15.DOI:10.16032/j.issn.1004-4965.2026.051
CMA-GD对春季偏东气流影响下海南岛局地暴雨预报的偏差分析
Bias Analysis of the CMA-GD Model Prediction for Localized Heavy Rainfall over Hainan Island During Spring Easterly Flow
摘要
Abstract
During spring,Hainan Island is prone to localized heavy rainfall over its eastern hilly and plain regions driven by low-level easterly airflow.However,significant forecast biases persist in operational convective-scale numerical models.This study evaluates the performance of the CMA-GD mesoscale model(3 km resolution)in simulating these localized heavy rainfall events during 2021-2023 utilizing high-density automatic weather station observations,1-km resolution CLDAS(CMA Land Data Assimilation System)land surface datasets,and ERA5 reanalysis data.The results indicate that while the model adequately simulate afternoon heavy rainfall over the central-western mountains,it consistently underestimates daytime and early morning heavy rainfall occurring during the in the east.Consequently,the model fails to capture the observed bimodal d diurnal cycle of mean precipitation.Synoptically,these errors are linked to the misrepresentation of the offshore cold high-pressure system.The model exhibits a systematic clockwise bias(approximately 30 °)in the low-level(below 850 hPa)wind direction and overestimates wind speeds below 925 hPa by 2-3 m·s-1 compared to observations.Concurrently,it underestimates specific humidity(approximately 2 g·kg-1)and relative humidity(～12%,)respectively,at 1 000 hPa and Diagnostic analysis of typical cases reveals five primary mechanisms for underestimation of heavy rainfall:(1)The clockwise wind direction bias weakens frontogenesis within convergent flows;(2)The low-level dry bias elevates the Lifting Condensation Level(LCL)and Level of Free Convection(LFC);(3)Insufficient surface friction reduces forecast convergence,inhibiting convective initiation;(4)Inadequate representation of the horizontal and vertical wind shear perpendicular to the terrain;and(5)Forecast biases in land surface temperature disrupt local sea-land breeze circulations,altering precipitation patterns.关键词
春季低层偏东风/海南岛/暴雨/CMA-GD/预报偏差Key words
spring low-level easterly winds/Hainan Island/heavy rainfall/CMA-GD/forecast bias分类
天文与地球科学引用本文复制引用
吴俞,冯箫,朱科锋,李勋,杨薇,石娟..CMA-GD对春季偏东气流影响下海南岛局地暴雨预报的偏差分析[J].热带气象学报,2026,42(4):540-554,15.基金项目
国家自然科学基金(42530611) （42530611）
全国暴雨研究开放基金(BYKJ2025M24) （BYKJ2025M24）
海南省自然科学基金项目(425QN500)共同资助 （425QN500）
