arXiv:2505.02979physics.ao-phcs.LG2025-05

用神经物理框架直接优化地表模型参数,无需反向传播推导。

Parameter estimation for land-surface models using Neural Physics

  • 基于可微分物理模型,通过梯度下降直接估计参数。
  • 单层土壤温度假设下参数不可靠,双层数据可准确估计关键热参数。
  • 适用于城市通量塔数据,适合气候建模与环境监测研究者。

我们提出一种新型反演方法,通过将数据同化到基于卷积运算的可微分物理前向模型中,估计简单地表模型(LSM)的参数。控制方程在神经物理框架内表达,实现时间依赖参数的直接梯度优化,无需推导和维护伴随模型。参数通过最小化模型预测与合成或观测数据之间的偏差来估计。尽管可微性由机器学习库实现,但前向模型仍完全基于物理,且不涉及训练过程。评估中,先以已知参数运行前向模型生成合成土壤温度观测,再将其作为未知参数求解逆问题。结果表明,单层土壤温度假设下无法可靠约束参数;而使用双层观测数据时可获得可靠参数估计,但无法区分潜热与感热通量的贡献。此外,该方法应用于美国凤凰城城市通量塔数据,成功估计了热传导率、体积热容及感潜热综合传输系数,同时使用观测表面反照率。模型准确预测了长波辐射、土壤导热通量及综合感潜热通量,证明神经物理框架可用于准确确定所用特定地表模型的参数。

原文摘要 · Abstract (English)

We propose a novel inverse-modelling approach that estimates the parameters of a simple land-surface model (LSM) by assimilating data into a differentiable, physics-based forward model formulated using convolutional operations. The governing equations are expressed within the Neural Physics framework, allowing direct gradient-based optimisation of time-dependent parameters without the need to derive and maintain adjoint formulations. The model parameters are estimated by minimising the mismatch between model predictions and synthetic or observational data. Although differentiability is enabled through machine-learning libraries, the forward model itself remains entirely physics-based and neither the forward model nor the parameter estimation procedure involve training. To evaluate the approach, we first generate synthetic observations of soil temperature by running the forward model with known parameter values and subsequently treat these parameters as unknown in an inverse problem. We show that observations of soil temperature at a single depth are insufficient to reliably constrain the model parameters. Using observations at two depths, however, does yield reliable parameter estimates, although the individual contributions of latent and sensible heat fluxes cannot be distinguished. We also apply the approach to urban flux tower data from Phoenix, United States, and show that the thermal conductivity, volumetric heat capacity and the combined sensible-latent heat transfer coefficient can be reliably estimated whilst using an observed value for the effective surface albedo. The resulting model accurately predicts the outgoing longwave radiation, conductive soil fluxes and the combined sensible-latent heat fluxes, demonstrating that the Neural Physics framework can be used to accurately determine the parameters of the particular LSM used here...

地表模型参数估计神经物理可微分物理

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