arXiv:2605.29172cs.LGphysics.ao-ph2026-05

用生成模型修正北极海冰季节预测偏差,提升精度与细节清晰度。

Probabilistic bias adjustment of seasonal forecasts using generative machine learning: A case study of Arctic sea ice predictions

论文配图:Probabilistic bias adjustment of seasonal forecasts using generative machine learning: A case study of Arctic sea ice predictions
图 1 · 摘自论文原文
  • 用条件变分自编码器生成修正后的预测,学习观测分布。
  • 修正后预测更贴近真实数据,误差更小,分辨率更高。
  • 适合气候预测、极地研究及需要高精度预报的决策者。

季节性气候预测通过提供未来数月最可能的气候状况及其不确定性信息,支持规划与风险管理。集合预报通过模拟多种可能结果,将预测表达为可用概率。大规模集合和高分辨率预报能更好采样不确定性并捕捉细尺度过程,但计算成本高。此外,预报集合随提前期增长出现系统性偏差和时空误差,需精细后处理校准。加拿大气候建模与分析中心开发了一种基于条件变分自编码器(cVAE)的概率后处理框架,用于生成大样本的北极海冰偏置修正季节预测。该生成模型学习在有偏模型预测条件下观测分布。本研究进一步改进该框架,解决标准cVAE预测中细尺度能量损失和模糊问题:采用生成器替代cVAE中的高斯解码器,并以连续排名概率评分(CRPS)替代均方误差作为目标函数;同时使用比原始预报更高分辨率的目标数据集。结果显示,修正后预测具有更好的校准性、更强的观测分布一致性,且误差更小,同时提升了原始预报的分辨率,改善了锐度与谱功率,优于基准预测。

原文摘要 · Abstract (English)

Seasonal climate predictions support planning and risk management by offering early information of the most likely-to-occur climate conditions in the coming months, and associated uncertainties. Ensemble forecasts enable this by simulating many plausible outcomes, allowing predictions to be expressed as usable probabilities. Large ensembles and high-resolution forecasts strengthen this guidance by better sampling uncertainty and capturing finer-scale processes but come with significant computational cost. Moreover, forecast ensembles drift and exhibit systematic biases and spatio-temporal errors that grow with lead time, requiring careful post-processing and calibration. A probabilistic post-processing framework based on conditional Variational Autoencoders (cVAEs) was developed at the Canadian Center for Climate Modeling and Analysis to generate large ensembles of bias adjusted seasonal predictions of Arctic sea ice. The generative model was designed to learn the observational distribution conditioned on the biased model prediction. This enables generation of arbitrarily large ensembles of well-calibrated, bias corrected forecasts with improved skill. Here, we extend this framework to address the loss of fine-scale energy and the characteristic blurriness in predictions, a known limitation of standard cVAEs. Specifically, we employ a generator in place of the Gaussian parametrized decoder in the cVAE and use Continuous Ranked Probability Score in the objective function instead of the Mean Square Error. We further use a higher resolution target dataset compared to the raw forecast. We show that the adjusted forecasts are better calibrated, more consistent with the observational distribution, and exhibit smaller errors than benchmark predictions, while also enhancing the resolution of the raw forecasts and improving sharpness and spectral power relative to the standard cVAE.

气候预测生成模型北极海冰概率校准

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