用输入扰动构建图神经网络集合,提升海温预报不确定性刻画能力。
Ensemble Graph Neural Networks for Probabilistic Sea Surface Temperature Forecasting via Input Perturbations
- 通过扰动初始海洋状态生成模型集合,无需重复训练。
- 低分辨率佩林噪声扰动使15天预报的CRPS降低,校准效果更好。
- 适合需要可靠概率预报的区域海洋预测业务应用。
精准的区域海洋预报需兼顾计算效率与预测不确定性表征。本文研究基于图神经网络(GNN)的海表温度(SST)预报中集成学习策略,重点分析输入扰动设计对预报性能和不确定性表达的影响。将GNN架构应用于北大西洋加那利群岛区域,采用类似袋装(bagging)的同质集成方法,在推理阶段通过扰动初始海洋状态引入多样性,而非重新训练多个模型。评估了高斯噪声、佩林噪声及分形佩林噪声等多种基于噪声的集成生成策略,系统调整噪声强度与空间结构。在15天预报周期内,使用确定性指标(均方根误差RMSE与偏差)和概率指标(连续排序概率评分CRPS及展布-技能比)进行评估。结果表明,虽然确定性性能与单模型相当,但输入扰动类型与结构显著影响不确定性表达,尤其在长预报时效下。具有空间相干性的扰动(如低分辨率佩林噪声)在15天预报中表现出更优的校准性和更低的CRPS,优于纯随机高斯扰动。研究揭示噪声结构与尺度在集成GNN设计中的关键作用,证明精心构造的输入扰动可实现无额外训练成本的良校准概率预报,支持集成GNN在业务化区域海洋预报中的可行性。
原文摘要 · Abstract (English)
Accurate regional ocean forecasting requires models that are both computationally efficient and capable of representing predictive uncertainty. This work investigates ensemble learning strategies for sea surface temperature (SST) forecasting using Graph Neural Networks (GNNs), with a focus on how input perturbation design affects forecast skill and uncertainty representation. We adapt a GNN architecture to the Canary Islands region in the North Atlantic and implement a homogeneous ensemble approach inspired by bagging, where diversity is introduced during inference by perturbing initial ocean states rather than retraining multiple models. Several noise-based ensemble generation strategies are evaluated, including Gaussian noise, Perlin noise, and fractal Perlin noise, with systematic variation of noise intensity and spatial structure. Ensemble forecasts are assessed over a 15-day horizon using deterministic metrics (RMSE and bias) and probabilistic metrics, including the Continuous Ranked Probability Score (CRPS) and the Spread-skill ratio. Results show that, while deterministic skill remains comparable to the single-model forecast, the type and structure of input perturbations strongly influence uncertainty representation, particularly at longer lead times. Ensembles generated with spatially coherent perturbations, such as low-resolution Perlin noise, achieve better calibration and lower CRPS than purely random Gaussian perturbations. These findings highlight the critical role of noise structure and scale in ensemble GNN design and demonstrate that carefully constructed input perturbations can yield well-calibrated probabilistic forecasts without additional training cost, supporting the feasibility of ensemble GNNs for operational regional ocean prediction.
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