用简单方法实现顶尖天气预报,训练快10倍、推理快10倍。
U-Cast: A Surprisingly Simple and Efficient Frontier Probabilistic AI Weather Forecaster

- 基于标准U-Net,先用MAE预训练再用CRPS微调,仅需简单流程。
- 在1.5°分辨率下性能超GenCast和IFS ENS,训练计算量减少10倍以上。
- 适合想低成本部署前沿概率天气模型的研究者与团队。
基于AI的天气预报已媲美传统物理集合预报,但当前最先进模型依赖专用架构与巨大算力,门槛高。我们证明此类复杂性对顶尖性能并非必需。提出 extit{U-Cast},一个基于标准U-Net的概率预报器,采用简单训练流程:先在平均绝对误差(MAE)上进行确定性预训练,再用蒙特卡洛丢弃实现随机性的连续排名概率评分(CRPS)短时微调。结果表明,该模型在1.5°分辨率下性能达到或超越GenCast和IFS ENS,训练算力低于领先CRPS模型10倍以上,推理延迟低于扩散模型10倍以上。U-Cast训练耗时不足12个H200 GPU天,可在3秒内生成15天集合预报。这些结果表明,通用可扩展架构结合高效训练方案,可在极低成本下实现复杂领域专用设计的顶尖表现,为更广泛社区提供前沿概率天气建模的新可能。
原文摘要 · Abstract (English)
AI-based weather forecasting now rivals traditional physics-based ensembles, but state-of-the-art (SOTA) models rely on specialized architectures and massive computational budgets, creating a high barrier to entry. We demonstrate that such complexity is unnecessary for frontier performance. We introduce \ours, a probabilistic forecaster built on a standard U-Net backbone trained with a simple recipe: deterministic pre-training on Mean Absolute Error followed by short probabilistic fine-tuning on the Continuous Ranked Probability Score (CRPS) using Monte Carlo Dropout for stochasticity. As a result, our model matches or exceeds the probabilistic skill of GenCast and IFS ENS at $1.5^\circ$ resolution while reducing training compute by over $10\times$ compared to leading CRPS-based models and inference latency by over $10\times$ compared to diffusion-based models. U-Cast trains in under 12 H200 GPU-days and generates a 15-day ensemble forecast in 3 seconds. These results suggest that scalable, general-purpose architectures paired with efficient training curricula can match complex domain-specific designs at a fraction of the cost, opening the training of frontier probabilistic weather models to the broader community.
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