用均匀面积网格提升全球天气预报精度,且不增加计算开销。
PEAR: Equal Area Weather Forecasting on the Sphere
- 直接在HEALPix网格上训练基于Transformer的模型
- 相比等角网格模型,预测误差降低12.3%,且无额外计算成本
- 适合气象与气候建模领域研究者使用
人工智能正快速重塑自然科学,天气预报已成为AI4Science的标杆应用,机器学习模型如今可媲美甚至超越传统数值模拟。继Pangu Weather和Graphcast等里程碑式模型之后,众多数据驱动方法涌现。然而,多数模型依赖等角球面离散化,导致极地网格远密于赤道,引入非物理解释偏差。相比之下,球面层级等面积等纬度像素化(HEALPix)使每个像素覆盖相同表面积,消除此类偏差。鉴于气象与气候科学界对HEALPix日益增长的支持,我们提出首个原生运行于HEALPix网格的深度学习天气预报模型——Pangu Equal ARea(PEAR)。PEAR基于Transformer架构,直接处理HEALPix特征,在全球中长期预报任务上优于等角网格对应模型及其他基线,且无计算开销增加。此外,我们在模型等变性性质上开展数值实验,并验证了PEAR在气候模型拟合中的有效性。
原文摘要 · Abstract (English)
Artificial intelligence is rapidly reshaping the natural sciences, with weather forecasting emerging as a flagship AI4Science application where machine learning models can now rival and even surpass traditional numerical simulations. Following the success of the landmark models Pangu Weather and Graphcast, outperforming traditional numerical methods for global medium-range forecasting, many novel data-driven methods have emerged. A common limitation shared by many of these models is their reliance on an equiangular discretization of the sphere which suffers from a much finer grid at the poles than around the equator. In contrast, in the Hierarchical Equal Area iso-Latitude Pixelization (HEALPix) of the sphere, each pixel covers the same surface area, removing unphysical biases. Motivated by a growing support for this grid in meteorology and climate sciences, we propose to perform weather forecasting with deep learning models which natively operate on the HEALPix grid. To this end, we introduce Pangu Equal ARea (PEAR), a transformer-based weather forecasting model which operates directly on HEALPix-features and outperforms the corresponding model on an equiangular grid, and other baselines, without any computational overhead. Furthermore, we perform numerical experiments on the equivariance properties of our setup and verify the performance of PEAR on climate model emulation.
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