用深度集成学习替代昂贵的碳再分析,高效预测欧洲大陆架碳储量。
Estimating carbon pools in the European Shelf sea environment: replacing reanalysis by model-informed machine learning?
- 基于物理-生物地球化学模型训练深度集成神经网络,学习环境变量与海洋碳库关系。
- 预测结果比原始模拟更接近再分析数据,且提供不确定性估计。
- 适合缺乏观测或观测不确时的碳储量估算,可支持气候情景模拟。
大陆架在经济和碳循环中至关重要,但碳库观测常稀疏或不确定。传统碳再分析(如融合叶绿素-a等代理变量或直接碳数据)虽可行,但计算成本高。本文提出一种计算高效的深度集成神经网络,从北西欧大陆架(NWES)物理-生物地球化学模型自由运行模拟中学习大气、河流及海洋可观测变量与海洋碳库之间的关系。训练完成后,使用再分析输入驱动该模型,预测多个碳库(如碎屑、浮游动物、异养细菌)表现优于原始模拟,且提供不确定性信息。进一步验证发现,当直接使用再分析中同化的观测数据驱动时,模型性能相当,但仅限于观测时空点。研究强调可解释性,并展示其在气候“假如”情景中的应用潜力。结果表明,模型引导的机器学习可作为昂贵再分析的可行替代方案,在观测缺失或不确定区域具有重要补充价值。
原文摘要 · Abstract (English)
Shelf seas are important for the economy and the carbon cycle, but shelf sea observations for carbon pools are often sparse, or highly uncertain. An alternative can be provided by carbon reanalyses (whether assimilating proxy variables, such as chlorophyll-$a$, or directly carbon), but these are often expensive to run. We propose to use a computationally cheap ensemble of neural networks (i.e. deep ensemble) to learn the relationship between the directly observable (atmospheric, riverine and ocean) variables and marine carbon pools from a coupled physics-biogeochemistry model. The deep ensemble was trained on a North-West European Shelf (NWES) physical-biogeochemistry model free run simulation. After training, the deep ensemble was run using inputs from the NWES reanalysis instead of the free run, demonstrating that it can efficiently predict several NWES carbon pools (e.g., detritus, zooplankton, heterotrophic bacteria) in much better agreement with the reanalysis than the free run, while also providing uncertainty information. We further show that the deep ensemble performs similarly well when it is driven directly by the observations assimilated into the reanalysis, with the limitation that carbon pools can then be predicted only at the observed locations and times. We focus on explainability of the results and demonstrate potential use of the deep ensembles for future climate what-if scenarios. We suggest that model-informed machine learning presents a viable alternative to expensive reanalyses and could complement observations, wherever they are missing and/or highly uncertain.
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