传统检验联合MODE检验在CPEFS模式春季降水预报中的应用
Application of combined traditional and MODE verification methods in spring precipitation forecast evaluation of CPEFS Model
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摘要: 研究采用传统检验与MODE 检验相结合的方法,对中国气象局人影中心研发的云降水显式预报系统(Cloud Precipitation Explicit Forecast System,CPEFS)2021—2023 年春季降水预报产品开展系统性评估。从预报时效、降水时段、量级阈值三个方面,评估了西风槽—冷涡型(WT-CV)和西风槽—切变线型(WT-SL)两类典型天气过程的预报产品。结果表明:CPEFS对两类天气过程的预报性能具有高度一致性。具体表现为14:00—20:00时段预报效果最优;≥1.0 mm降水预报评分显著优于≥10.0 mm降水,且系统预报能力随预报时效延长呈明显衰减趋势。但两类过程的预报误差成因存在本质差异,WT-CV型天气过程的核心误差为“强度高估”,源自模式系统性湿偏差,WT-SL型天气过程的关键问题为“位置偏差”,表现为显著的空间位移特征。传统检验可实现预报的客观量化评估,MODE 检验则能精准诊断空间结构误差来源。因此,建议在业务检验中采用“传统检验+MODE检验”的组合方案,实现对系统性能的多维度的综合评估,为降水预报业务提供更全面的技术支撑。Abstract: This study employs a combined approach of traditional verification and MODE (Method for Object-based Diagnostic Evaluation) to systematically evaluate the spring precipitation forecast products of the Cloud Precipitation Explicit Forecast System (CPEFS) model developed by the China Meteorological Administration Weather Modification Centre from 2021 to 2023.The evaluation focuses on two typical weather processes: the westerly trough-cold vortex type (WT-CV) and the westerly trough-shear line type (WT-SL),conducting in-depth analysis from three core aspects: forecast lead time,precipitation period,and magnitude threshold.The results indicate that the temporal evolution patterns of forecast performance for both weather processes exhibit high consistency.Specifically,the forecast performance is optimal during the 14:00-20:00;the forecast scores for precipitation ≥1.0 mm are significantly better than those for ≥10.0 mm;and the model forecast capability shows a pronounced decreasing trend with increasing forecast lead time.However,the causes of forecast errors for the two types differ fundamentally.For WT-CV type processes,the core error is "intensity overestimation" which originates from the systematic wet bias of the model.For WT-SL type processes,the key issue for is "position deviation," characterized by significant spatial displacement.Traditional verification enables objective quantitative evaluation of forecasts,while MODE verification can accurately diagnose the sources of spatial structure errors.Therefore,it is recommended to adopt a combined approach of "traditional verification+MODE verification" in operational verification to achieve multidimensional comprehensive evaluation of model performance,and to provide more comprehensive technical support for precipitation forecast operations.
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