用机器学习修正生态模型偏差,让碳吸收估算更准更可信。
UFLUX v2.0: A Process-Informed Machine Learning Framework for Efficient and Explainable Modelling of Terrestrial Carbon Uptake
- 融合生态知识与机器学习,自动学习模型与实测数据的偏差
- 误差降低近半,相关系数达0.79,优于原模型的0.51
- 适合关注碳循环、气候变化响应的研究者和政策制定者
光合固碳量(GPP)是理解全球碳循环和生态系统功能的关键。基于生态过程的模型因假设与近似存在偏差,导致全球GPP估算不确定性高,影响净零目标实现。本研究提出UFLUX v2.0,结合先进生态知识与机器学习技术,通过学习过程模型与涡度相关(EC)观测之间的偏差,降低估算误差。结果显示,UFLUX v2.0的决定系数(R²)达0.79,均方根误差(RMSE)降至1.60 g C m⁻² d⁻¹,显著优于原模型的R²=0.51、RMSE=3.09 g C m⁻² d⁻¹。尽管两者全球总GPP相近(分别为137.47和132.23 Pg C),但在空间分布上差异显著,尤其在纬度梯度上,反映出过程模型存在系统性偏差及对气候环境敏感性不同。该模型提升了跨生态系统适应性,深化了对全球碳循环及其响应机制的理解。
原文摘要 · Abstract (English)
Gross Primary Productivity (GPP), the amount of carbon plants fixed by photosynthesis, is pivotal for understanding the global carbon cycle and ecosystem functioning. Process-based models built on the knowledge of ecological processes are susceptible to biases stemming from their assumptions and approximations. These limitations potentially result in considerable uncertainties in global GPP estimation, which may pose significant challenges to our Net Zero goals. This study presents UFLUX v2.0, a process-informed model that integrates state-of-art ecological knowledge and advanced machine learning techniques to reduce uncertainties in GPP estimation by learning the biases between process-based models and eddy covariance (EC) measurements. In our findings, UFLUX v2.0 demonstrated a substantial improvement in model accuracy, achieving an R^2 of 0.79 with a reduced RMSE of 1.60 g C m^-2 d^-1, compared to the process-based model's R^2 of 0.51 and RMSE of 3.09 g C m^-2 d^-1. Our global GPP distribution analysis indicates that while UFLUX v2.0 and the process-based model achieved similar global total GPP (137.47 Pg C and 132.23 Pg C, respectively), they exhibited large differences in spatial distribution, particularly in latitudinal gradients. These differences are very likely due to systematic biases in the process-based model and differing sensitivities to climate and environmental conditions. This study offers improved adaptability for GPP modelling across diverse ecosystems, and further enhances our understanding of global carbon cycles and its responses to environmental changes.
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