用物理规律检验气候降尺度模型,发现其泛化能力差且不守物理定律。
Assessing the Geographic Generalization and Physical Consistency of Generative Models for Climate Downscaling
- 引入物理启发的诊断方法评估生成模型性能
- 模型在非训练区域表现显著下降,小尺度结构重建差
- 添加功率谱密度损失可提升跨区域泛化能力
公里级天气数据对实际应用至关重要,但传统气象模拟计算成本高。深度学习模型提供了更快的气候降尺度方案,但其可靠性存疑,因常仅依赖标准机器学习指标评估,缺乏大气与天气物理视角。本文基准测试了最新SOTA深度学习模型,并引入物理启发的诊断工具,重点评估地理泛化性和物理一致性。实验表明,尽管如CorrDiff等模型在有限欧洲地理区域(如中欧)表现良好,但在伊比利亚、北非摩洛哥或北欧斯堪的纳维亚等地泛化失败;且无法准确捕捉由速度场推导出的二阶变量,如散度和涡度。这些缺陷甚至出现在同分布地理区域中,表明预测缺乏物理一致性。我们提出简单解决方案:引入功率谱密度损失函数,实证显示该方法能有效促进小尺度物理结构重建,改善地理泛化能力。实验代码见https://github.com/CarloSaccardi/PSD-Downscaling。
原文摘要 · Abstract (English)
Kilometer-scale weather data is crucial for real-world applications but remains computationally intensive to produce using traditional weather simulations. An emerging solution is to use deep learning models, which offer a faster alternative for climate downscaling. However, their reliability is still in question, as they are often evaluated using standard machine learning metrics rather than insights from atmospheric and weather physics. This paper benchmarks recent state-of-the-art deep learning models and introduces physics-inspired diagnostics to evaluate their performance and reliability, with a particular focus on geographic generalization and physical consistency. Our experiments show that, despite the seemingly strong performance of models such as CorrDiff, when trained on a limited set of European geographies (e.g., central Europe), they struggle to generalize to other regions such as Iberia, Morocco in the south, or Scandinavia in the north. They also fail to accurately capture second-order variables such as divergence and vorticity derived from predicted velocity fields. These deficiencies appear even in in-distribution geographies, indicating challenges in producing physically consistent predictions. We propose a simple initial solution: introducing a power spectral density loss function that empirically improves geographic generalization by encouraging the reconstruction of small-scale physical structures. The code for reproducing the experimental results can be found at https://github.com/CarloSaccardi/PSD-Downscaling
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