用卷积神经过程将气象数据从11km提升到1km,精度超插值方法一半以上。
Exploring Convolutional Neural Processes for Weather Downscaling

- 基于卷积条件神经过程,融合高程特征进行气温降尺度建模。
- 平均误差1.31℃,比双线性插值误差降低52.4%。
- 地形特征是关键,但对非格点观测仍不适用,不确定性需校准。
全球再分析产品如ERA5-Land提供空间完整的气象场,但分辨率太粗,难以用于局部应用,尤其在山区温度短距离可变化数度。本研究探索卷积条件神经过程(ConvCNPs)对瑞士地区日最高气温从约11km分辨率降至约1km分辨率的统计降尺度,基于Vaughan等(2022)架构,并结合swisstopo DHM25提供的高分辨率高程数据以适应复杂地形。最佳模型在2014–2023年十年数据上经五折时间交叉验证,均方根误差为1.31℃,基于CRPS的技巧得分达0.524,相较双线性插值预期预测误差降低超过一半。消融实验显示,高程MLP是不可或缺组件——无此模块模型完全发散;季节特征与地形位置指数具次要增益。在输入稀疏时模型表现渐进下降,正技巧维持至约10%输入网格密度;然而,零样本部署于非格点站点观测未在任何密度下获得正技巧。所有配置均呈现严重过度自信的不确定性估计,系高斯似然训练目标的结构性缺陷。结果表明,ConvCNPs是复杂地形气候降尺度的有效方法,但不确定性校准及对非格点输入的原生支持仍是实际部署的关键挑战。
原文摘要 · Abstract (English)
Global reanalysis products such as ERA5-Land provide spatially complete weather fields but at resolutions too coarse for local applications, particularly in mountainous regions where temperature can vary by several degrees over short distances. This project investigates Convolutional Conditional Neural Processes (ConvCNPs) for statistical downscaling of daily maximum temperature from the ~11km resolution ERA5-Land grid to ~1km resolution over Switzerland, building upon the architecture of Vaughan et al. (2022) and adapting it to the topographically complex Swiss domain with high-resolution elevation features from the swisstopo DHM25. The best model, trained on ten years of data (2014-2023) with five-fold temporal cross-validation, achieves a mean absolute error of 1.31 Celsius and a CRPS-based skill score of 0.524 relative to bilinear interpolation, reducing the expected prediction error by more than half. An ablation study reveals that the elevation MLP is the indispensable component - without it, the model diverges entirely - while explicit seasonal features and Topographic Position Index provide secondary benefits. Under sparse on-grid input the model degrades gracefully, maintaining positive skill down to approximately 10% of the input grid; however, zero-shot deployment on off-grid station observations does not achieve positive skill at any density tested. All configurations exhibit severely overconfident uncertainty estimates, a structural limitation of the Gaussian likelihood training objective. These results demonstrate that ConvCNPs are a viable and effective approach to climate downscaling in complex terrain, and identify uncertainty calibration and native support for non-gridded input as the key challenges for operational deployment.
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