用可微方法模拟不可微科学指标,提升气候模型输出细节清晰度。
Emulating Non-Differentiable Metrics via Knowledge-Guided Learning: Introducing the Minkowski Image Loss

- 通过温度调节的连续逻辑运算,将非可微拓扑操作转为可微形式。
- 构建基于谱归一化的神经代理模型,在真实数据集上实现高精度几何还原。
- 适用于需要精确形态结构的气候建模任务,尤其适合生成式模型融合使用。
地球系统深度学习中存在‘可微性鸿沟’:由于无法直接对不可微的科学指标进行训练,模型只能依赖平滑代理(如MSE),常导致输出模糊、丢失高频细节。本文提出一种框架,通过两种方式弥合该鸿沟:一是解析近似,将离散拓扑操作用温度控制的sigmoid函数与连续逻辑运算替代;二是学习科学泛函的可微代理。我们采用具有谱归一化和硬结构约束的Lipschitz卷积神经网络稳定梯度训练。在EUMETNET OPERA数据集上验证,所提出的神经代理完全消除了基线模型中的几何违规问题。但在确定性超分辨率任务中发现:严格的Lipschitz正则化虽保证优化稳定性,却会过度平滑梯度信号,限制对强局部对流纹理的恢复。该研究强调需将此类拓扑约束与随机生成架构结合,才能实现完整形态真实性。
原文摘要 · Abstract (English)
The ``differentiability gap'' presents a primary bottleneck in Earth system deep learning: since models cannot be trained directly on non-differentiable scientific metrics and must rely on smooth proxies (e.g., MSE), they often fail to capture high-frequency details, yielding ``blurry'' outputs. We develop a framework that bridges this gap using two different methods to deal with non-differentiable functions: the first is to analytically approximate the original non-differentiable function into a differentiable equivalent one; the second is to learn differentiable surrogates for scientific functionals. We formulate the analytical approximation by relaxing discrete topological operations using temperature-controlled sigmoids and continuous logical operators. Conversely, our neural emulator uses Lipschitz-convolutional neural networks to stabilize gradient learning via: (1) spectral normalization to bound the Lipschitz constant; and (2) hard architectural constraints enforcing geometric principles. We demonstrate this framework's utility by developing the Minkowski image loss, a differentiable equivalent for the integral-geometric measures of surface precipitation fields (area, perimeter, connected components). Validated on the EUMETNET OPERA dataset, our constrained neural surrogate achieves high emulation accuracy, completely eliminating the geometric violations observed in unconstrained baselines. However, applying these differentiable surrogates to a deterministic super-resolution task reveals a fundamental trade-off: while strict Lipschitz regularization ensures optimization stability, it inherently over-smooths gradient signals, restricting the recovery of highly localized convective textures. This work highlights the necessity of coupling such topological constraints with stochastic generative architectures to achieve full morphological realism.
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