人工智能模型与传统数值预报对极端温度事件的集合预报对比分析

Comparison of extreme temperature ensemble forecasts between artificial intelligence models and physics-based numerical weather prediction

  • 摘要: 极端温度事件对人类社会和经济活动有着重要影响,但其预报仍存在较大的不确定性,因此,利用集合预报方法来合理表征这种不确定性尤为重要。基于盘古气象模型(Pangu-Weather,PGW),利用中国气象局全球中期集合预报系统(China Meteorological Administration Global Ensemble Prediction System,CMA-GEPS)的扰动初值构建了盘古气象中期集合预报系统(PGW-GEPS),并以2022年浙江极端高温事件和2024年内蒙古寒潮事件为例,对比分析了PGW-GEPS与CMA-GEPS集合预报对这两次极端温度事件的中期预报能力。结果显示,在浙江高温事件和内蒙古寒潮事件中,PGW-GEPS对极端温度预报不确定性的描述能力和准确性与CMA-GEPS相当,均能较好表征2 m温度预报不确定性随预报时长增长而增大的特征。但在浙江高温事件中,PGW-GEPS对切变线预报存在不足,中期预报表现出较大的误差。进一步对比分析了这两次极端温度事件的动能谱特征,发现PGW-GEPS次天气尺度以下的动能谱存在衰减现象。总体而言,基于人工智能模型的PGW-GEPS对极端温度事件具有预报能力,特别是3—10 d的极端温度预报准确性与CMA-GEPS具有可比性,且计算速度方面具有一定优势。然而,PGW-GEPS在表征快速变化的中小尺度天气系统方面仍有不足,需要进一步提升对次天气尺度系统预报能力。为人工智能模型在集合预报领域的应用提供了重要参考。

     

    Abstract: Extreme temperature events have significant impacts on human society and economic activities, yet the prediction still involves considerable uncertainties, making the use of ensemble forecasting methods crucial. The Pangu-Weather Global Ensemble Prediction System (PGW-GEPS) was developed by integrating the Pangu-Weather (PGW) with perturbed initial conditions of the China Meteorological Administration Global Ensemble Prediction System (CMA-GEPS). Using the 2022 extreme heat wave event in Zhejiang and the 2024 cold wave event in Inner Mongolia as two cases, the forecasting performances of PGW-GEPS and CMA-GEPS on these two extreme temperature events are evaluated and compared based on multiple assessment metrics. The results indicate that, for both the Zhejiang heat wave and Inner Mongolia cold wave event, PGW-GEPS exhibits forecast accuracy and uncertainty representation capabilities comparable to CMA-GEPS. Both systems effectively capture the increase in 2 m temperature forecast uncertainty with longer lead times and its subsequent decrease as the forecast initialization approaches the observation period. However, for the Zhejiang heat wave, PGW-GEPS shows deficiencies in forecasting the shear line and exhibits larger forecast errors in the medium range. A comparative analysis of the kinetic energy spectra of these two events further reveals that PGW-GEPS exhibits an attenuation phenomenon below the sub-synoptic scale. In summary, the AI-based PGW-GEPS demonstrates its forecasting capability for extreme temperature events. Its forecast accuracy for 3—10-day extreme temperature prediction is comparable to that of CMA-GEPS, while its computational speed is advantageous. However, PGW-GEPS still faces challenges in capturing rapidly evolving meso-micro scale weather systems, and further improvement in forecasting sub-synoptic systems is required. This study provides valuable insights into the application of artificial intelligence models in ensemble forecasting.

     

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