arXiv:2608.21998cs.LGcs.NA2026-08

提出DySCo方法,实现气候模型极端事件高分辨率降尺度的动态一致性。

DySCo: Dynamically consistent data-driven downscaling of extremes in climate projections

论文配图:DySCo: Dynamically consistent data-driven downscaling of extremes in climate projections
图 1 · 摘自论文原文
  • 基于数据驱动的变分同化思想,构建动态配对训练轨迹以保持动力学一致性。
  • 在LENS2模型上验证,与粗分辨率模拟轨迹保持高度一致,同时保留统计性能优势。
  • 适合需要因果分析的极端气候事件风险评估,如防灾规划与保险决策。

区域气候风险评估对基础设施设计、灾害预测和保险资源配置至关重要。然而,使用全球气候模型(GCM)估算高空间分辨率的区域风险计算成本过高,推动了对粗分辨率GCM输出进行降尺度的方法发展。降尺度对罕见事件尤为重要,因为量化其极端特性需高分辨率及极长的GCM模拟时间。此类方法非侵入式提升GCM分辨率,并校正因未解析小尺度过程导致的统计偏差,从而改善长重现期极端事件的统计精度。关键挑战在于保持动力学一致性:自由演化的GCM轨迹不应偏离用于训练校正算子的观测数据集。这对因果极端事件分析至关重要,例如基于故事情节的风险评估(即极端事件目录)对有效规划不可或缺。本文提出动态与统计一致的降尺度方法(DySCo),一种非侵入式框架,生成与粗分辨率GCM动力学一致的高分辨率气候投影。DySCo通过数据驱动重构的约束方法,创建无需修改GCM的动态配对训练轨迹。利用这些轨迹,训练出两阶段、兼具动态与统计一致性的算子。在时间与空间维度上对社区地球系统模型2大集合(LENS2)进行降尺度,目标为历史再分析数据。结果表明,DySCo在与粗分辨率轨迹的动态一致性方面表现优异,仅施加最小且因果的修正,同时保持与现有最先进无监督模型相当的统计性能。

原文摘要 · Abstract (English)

Regional climate risk assessment is critical for applications such as infrastructure design, disaster forecasting, and insurance resource allocation. However, estimating regional (i.e., high-spatial-resolution) risk with global climate models (GCMs) remains computationally prohibitive, which has driven the development of downscaling methods for coarse GCM outputs. Downscaling is vital for rare events, since quantifying their extreme properties requires high spatial resolution and very long GCM simulations. These methods non-intrusively increase GCM resolution while correcting statistical biases from unresolved fine-scale processes, thereby improving the accuracy of extreme event statistics with long return periods. A key challenge is preserving dynamical consistency, as freely evolving GCM trajectories are not expected to track the observational dataset used for training the correction operator. This is critical for causal extreme event analyses, where storyline-based risk assessment, i.e., extreme event catalogs, is necessary for effective planning. We address this challenge by introducing Dynamically and Statistically Consistent downscaling (DySCo), a non-intrusive framework yielding high-resolution climate projections consistent with coarse GCM dynamics. DySCo relies on a data-driven reformulation of nudging to create dynamically paired training trajectories without intrusive GCM modifications. Using these paired trajectories, we train a dynamically and statistically consistent, two-stage operator. We evaluate the method by downscaling the Community Earth System Model v2 Large Ensemble (LENS2) in time and space towards historical reanalysis. Results show DySCo achieves superior dynamical consistency with the coarse GCM trajectories, essentially applying a minimal, causal correction to the GCM, preserving top statistical performance comparable to state-of-the-art unsupervised models.

气候建模降尺度极端事件

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