集成最大稳定过程与贝叶斯模型平均以预测多模式集合中的极端气候事件
Integration of max-stable processes and Bayesian model averaging to predict extreme climatic events in multi-model ensembles
AI总结:
针对传统嵌入GEV的BMA方法忽略空间依赖性的问题,提出集成最大稳定过程的MSP-BMA方法,在韩国极端降雨预测中实现方差降低,且无需重网格化操作。
摘要:
极端气候的变化预测有时会采用多模式集合方法,例如嵌入广义极值分布(GEV)的贝叶斯模型平均(BMA)。BMA是一种常用的单个模拟模型预测结果组合方法,通过加权平均整合结果,并表征模型结构模拟带来的不确定性,该方法被称为嵌入GEV的BMA。但它基于极端事件的逐点分析,忽略了相邻网格单元之间的空间依赖性。为提升预测精度,研究者常采用最大稳定过程(MSP)这类空间极值模型替代逐点模型,以纳入空间依赖关系。\n本文提出一种将MSP集成到BMA中的方法,下文称为MSP-BMA。研究利用朝鲜半岛的极端降雨强度数据,验证了该方法相较于嵌入GEV的BMA的优越性,数据来自耦合模式比较计划第5阶段(CMIP5)多模式集合。研究采用名为APHRODITE(亚洲高分辨率观测降水数据集成评估数据集,版本v1101)的再分析数据以及17个CMIP5模式,针对韩国的10个网格单元开展验证。结果表明,MSP-BMA相比嵌入GEV的BMA实现了方差降低,同时也讨论了MSP-BMA相较于后者的偏差膨胀问题。MSP-BMA的一项附带技术优势是分析前后无需进行繁琐的“重网格化”操作,而嵌入GEV的BMA则必须执行该步骤。
英文摘要:
Projections of changes in extreme climate are sometimes predicted by using multi-model ensemble methods such as Bayesian model averaging (BMA) embedded with the generalized extreme value (GEV) distribution. BMA is a popular method for combining the forecasts of individual simulation models by weighted averaging and characterizing the uncertainty induced by simulating the model structure. This method is referred to as the GEV-embedded BMA. It is, however, based on a point-wise analysis of extreme events, which means it overlooks the spatial dependency between nearby grid cells. Instead of a point-wise model, a spatial extreme model such as the max-stable process (MSP) is often employed to improve precision by considering spatial dependency. We propose an approach that integrates the MSP into BMA, which is referred to as the MSP-BMA herein. The superiority of the proposed method over the GEV-embedded BMA is demonstrated by using extreme rainfall intensity data on the Korean peninsula from Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-models. The reanalysis data called APHRODITE (Asian Precipitation Highly-Resolved Observational Data Integration Towards Evaluation, v1101) and 17 CMIP5 models are examined for 10 grid boxes in Korea. In this example, the MSP-BMA achieves a variance reduction over the GEV-embedded BMA. The bias inflation by MSP-BMA over the GEV-embedded BMA is also discussed. A by-product technical advantage of the MSP-BMA is that tedious `regridding' is not required before and after the analysis while it should be done for the GEV-embedded BMA.
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