An introduction of the ensemble prediction scheme of CMA-CPSv3

  • 摘要: 集合预报是提升天气预报、次季节-季节预测(指15—60 d预测)和季节预测(一般指春夏秋冬的逐月预测)、年际预测及气候变化模拟能力的关键手段,在气象领域备受关注。本文介绍了中国气象局第三代气候模式预测业务系统(CMA-CPSv3)的集合预测方案。该方案融合了大气物理过程倾向随机扰动、海-气通量随机扰动和时间滞后初值扰动。基于BCC-CSM2-HR高分辨率气候模式,构建了在集合离散度、稳定性和可靠性方面表现良好的多圈层随机扰动集合预测系统。20 a历史回算数据的检验评估显示,CMA-CPSv3集合预测方案显著提升了中国降水和2 m气温的预测能力,同时也改善了厄尔尼诺-南方涛动(ENSO)、印度洋偶极子(IOD)及亚洲季风指数的预测效果。其中,增加海-气通量随机扰动对ENSO、东南亚季风和西北太平洋夏季风预测的改进尤为明显,为进一步表征气候系统模式中其他分量模式的不确定性提供了有益参考。

     

    Abstract: Ensemble prediction has been an important tool for weather forecasting, sub-seasonal to seasonal prediction, seasonal prediction, interannual prediction and even simulation of climate change, which has garnered widespread attention in the field of meteorology. This paper introduces the ensemble prediction scheme of China Meteorological Administration Climate Prediction System Version 3 (CMA-CPSv3). In this scheme, we adopt the approach of combining stochastic perturbations of physical process tendencies in the atmosphere, the air-sea flux and time-lagged initial values. Based upon the Version 2 of High-Resolution Beijing Climate Centre Climate System Model (BCC-CSM2-HR), we have developed a multi-layer random perturbation ensemble prediction system with relatively good ensemble sample dispersion, stability, and reliability. Results of evaluation for hindcasts over the past 20 years show that this ensemble prediction system significantly improves the prediction of precipitation and 2 m temperature over China, as well as the El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Asian Monsoon. In particular, the random perturbation of air-sea flux shows a positive effect on improving the prediction skills of ENSO and Southeast Asian Monsoon (SEAM) and Western North Pacific Summer Monsoon (WNPSM) indices. This study offers useful insights for further characterizing uncertainty in other component models of the climate system.

     

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