气候变化领域集成服务门户(CCPortal): A new mathematical framework for atmospheric blocking events

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DOI	10.1007/s00382-019-05018-2
	A new mathematical framework for atmospheric blocking events
	Lucarini V.; Gritsun A.
发表日期	2020
ISSN	0930-7575
起始页码	575
结束页码	598
卷号	54 期号:2020-01-02
英文摘要	We use a simple yet Earth-like hemispheric atmospheric model to propose a new framework for the mathematical properties of blocking events. Using finite-time Lyapunov exponents, we show that the occurrence of blockings is associated with conditions featuring anomalously high instability. Longer-lived blockings are very rare and have typically higher instability. In the case of Atlantic blockings, predictability is especially reduced at the onset and decay of the blocking event, while a relative increase of predictability is found in the mature phase. The opposite holds for Pacific blockings, for which predictability is lowest in the mature phase. Blockings are realised when the trajectory of the system is in the neighbourhood of a specific class of unstable periodic orbits (UPOs), natural modes of variability that cover the attractor the system. UPOs corresponding to blockings have, indeed, a higher degree of instability compared to UPOs associated with zonal flow. Our results provide a rigorous justification for the classical Markov chains-based analysis of transitions between weather regimes. The analysis of UPOs elucidates that the model features a very severe violation of hyperbolicity, due to the presence of a substantial variability in the number of unstable dimensions, which explains why atmospheric states can differ a lot in term of their predictability. Additionally, such a variability explains the need for performing data assimilation in a state space that includes not only the unstable and neutral subspaces, but also some stable modes. The lack of robustness associated with the violation of hyperbolicity might be a basic cause contributing to the difficulty in representing blockings in numerical models and in predicting how their statistics will change as a result of climate change. This corresponds to fundamental issues limiting our ability to construct very accurate numerical models of the atmosphere, in term of predictability of the both the first and of the second kind in the sense of Lorenz. © 2019, The Author(s).
英文关键词	Atmospheric blockings; Covariant Lyapunov vectors; Lyapunov exponents; Numerical modelling; Predictability; Unstable periodic orbits
语种	英语
scopus关键词	atmospheric blocking; atmospheric modeling; climate prediction; instability; Markov chain; numerical model; vector; Atlantic Ocean; Pacific Ocean
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/145756
作者单位	Department of Mathematics and Statistics, University of Reading, Reading, United Kingdom; Centre for the Mathematics of Planet Earth, University of Reading, Reading, United Kingdom; CEN, University of Hamburg, Hamburg, Germany; Institute of Numerical Mathematics, Russian Academy of Sciences, Moscow, Russian Federation
推荐引用方式 GB/T 7714	Lucarini V.,Gritsun A.. A new mathematical framework for atmospheric blocking events[J],2020,54(2020-01-02).
APA	Lucarini V.,&Gritsun A..(2020).A new mathematical framework for atmospheric blocking events.Climate Dynamics,54(2020-01-02).
MLA	Lucarini V.,et al."A new mathematical framework for atmospheric blocking events".Climate Dynamics 54.2020-01-02(2020).