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CMA-REPS登陆台风路径预报误差特征及订正技术

Error Characteristics and Correction Techniques of CMA-REPS Landing Typhoon Path Forecast

  • 摘要: 以2016年登陆中国大陆的“尼伯特”、“妮妲”、“莫兰蒂”和“鲇鱼”台风为例,利用中国气象局区域集合预报系统(China Meteorological Administration-Regional Ensemble Prediction System, CMA-REPS)集合预报产品,对台风路径、登陆时间和登陆地点进行集合预报检验。在此基础上,结合台风实时业务定位资料,提出了一种新的0~12 h最小累积路径误差(0~12 h Minimum Cumulative Track Error Scheme, MCTES)集合预报台风路径实时优选方案,并与12 h最小路径误差(12 h Minimum Track Error Scheme, MTES)集合预报台风路径实时优选方案进行对比分析,以期为更有效地业务应用CMA-REPS台风路径集合预报产品提供依据。结果表明:(1)在登陆台风路径预报方面,总体而言,CMA-REPS的集合平均预报效果不及控制预报;(2)MCTES集合预报台风路径实时优选方案明显改进了CMA-REPS的集合平均和控制预报的台风路径结果,其效果依次优于MTES方案、CMA-REPS的控制预报和集合平均。与控制预报相比,MCTES方案预报的台风登陆时间、登陆点和24~72 h时效内每隔12 h台风移动路径的平均绝对误差分别减少了0.4 h、34.3 km和21.1 km;与集合平均相比,上述误差则分别减少了1.1 h、36.4 km和29.6 km;(3)将MCTES方案选出的最优成员与控制预报成员进行集成,台风路径预报误差进一步降低。与集合平均相比,控制预报台风路径平均距离误差减少了﹣5.21 %~11.51 %;MCTES方案将平均距离误差的减少幅度提升至13.42 %~19.83 %;而MCTES与控制预报的集成方案则进一步将平均距离误差的减少幅度提升为16.28 %~20.83 %。

     

    Abstract: Taking the landfall typhoons "Nepartak", "Nida", "Meranti", and "Megi" in mainland China in 2016 as examples, this study evaluates the ensemble forecasts of typhoon track, landfall time, and landfall location using products from the China Meteorological Administration-Regional Ensemble Prediction System (CMA-REPS). On this basis, a new real-time optimal selection scheme for typhoon track ensemble forecasts, the 0~12 h Minimum Cumulative Track Error Scheme (MCTES), is proposed by combining operational real-time typhoon positioning data. This scheme is compared with the 12 h Minimum Track Error Scheme (MTES) to provide a reference for more effective operational applications of CMA-REPS typhoon track ensemble forecasts. The results show as follows. (1) Overall, in terms of typhoon track forecasting for landfalling typhoons, the ensemble mean forecast of CMA-REPS is inferior to the control forecast. (2) The MCTES real-time optimal typhoon track ensemble forecast selection scheme significantly improves the typhoon track results of both the CMA-REPS ensemble mean and control forecasts, outperforming the MTES scheme, CMA-REPS control forecast, and ensemble mean in sequence. Compared with the control forecast, the MCTES scheme reduced the average absolute errors in typhoon landing time, landing point, and the typhoon’s track movement every 12 h within the 24~72 h forecast validity time by 0.4 h, 34.3 km, and 21.1 km, respectively; compared with the ensemble mean, these errors are reduced by 1.1 h, 36.4 km, and 29.6 km, respectively. (3) Integrating the optimal members selected by the MCTES scheme with the control forecast members further reduces the typhoon track forecast errors. Compared with the ensemble mean, the average distance error in typhoon track for the control forecast was reduced by ﹣5.21 %~11.51 %; the MCTES scheme increased the reduction in average distance error to 13.42 %~19.83 %; and the integrated scheme of MCTES and control forecast further increased the reduction in average distance error to 16.28 %~20.83 %.

     

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