用简单扰动让AI天气模型预测极端事件更准,适合做预警系统。
On the Predictive Skill of Artificial Intelligence-based Weather Models for Extreme Events using Uncertainty Quantification
- 用高斯、Perlin等扰动生成50成员集合,提升确定性AI模型的不确定性表达。
- 温度极端事件预测效果优于降水,但整体仍落后于传统数值预报集合。
- 模型选择比扰动方法更重要,适合硬件受限场景下的早期预警应用。
准确预测极端天气仍是基于人工智能的天气预测系统的重大挑战。尽管如FuXi、GraphCast和SFNO等确定性模型在预报精度上已媲美数值天气预报,但其对不确定性的表征和极端事件的捕捉能力仍有限。本研究探究了前沿确定性AI模型对初始条件扰动的响应,并评估由此产生的集合预报在极端事件中的表现。采用四种扰动策略(高斯、Perlin噪声、半球中心繁殖向量HCBV、巨大集合HENS),为2022年8月巴基斯坦洪灾和中国高温事件生成50成员集合,并辅以全球阈值评估。集合技能通过与ERA5对比,并与IFS ENS和AIFS ENS概率模型使用确定性和概率性指标进行评估。结果表明,高斯和Perlin噪声等简单扰动生成的集合发散度和概率技能与基于流的方法(如HCBV、HENS)相当,缩小但未消除与数值天气预报集合或原生概率模型之间的性能差距。模型选择是集合表现的主导因素,而非扰动方法。在各类变量中,模型对温度极端事件的捕捉优于降水。研究显示,简单输入扰动可在硬件受限条件下将确定性模型扩展为概率预报,支持人工智能驱动的早期预警系统。
原文摘要 · Abstract (English)
Accurate prediction of extreme weather events remains a major challenge for artificial intelligence-based weather prediction systems. While deterministic models such as FuXi, GraphCast, and SFNO have achieved competitive forecast skill relative to numerical weather prediction, their ability to represent uncertainty and capture extremes is still limited. This study investigates how state-of-the-art deterministic artificial intelligence-based models respond to initial-condition perturbations and evaluates the resulting ensembles in forecasting extremes. Using four perturbation strategies (Gaussian, Perlin noise, Hemispheric Centered Bred Vectors, and Huge Ensembles), we generate 50 member ensembles for the August 2022 Pakistan floods and China heatwave, and complement these case studies with a global threshold-based evaluation. Ensemble skill is assessed against ERA5 and compared with IFS ENS and the AIFS ENS probabilistic model using deterministic and probabilistic metrics. Results show that simpler perturbations like Gaussian and Perlin noise produce similarly realistic ensemble spread and probabilistic skill as flow-based approaches like HCBV and HENS, narrowing but not closing the performance gap with numerical weather prediction ensembles, or native probabilistic models which retain the highest probabilistic skill across variables. Model choice is the dominant factor for ensemble performance, not perturbation method. Across variables, models capture temperature extremes more effectively than precipitation. These findings demonstrate that simple input perturbations can extend deterministic models toward probabilistic forecasting in hardware-constrained settings, supporting artificial intelligence-driven early warning systems.
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