Dansgaard-Oeschger事件概念模型的正则化。

IF 3.2 2区 数学 Q1 MATHEMATICS, APPLIED
Chaos Pub Date : 2025-08-01 DOI:10.1063/5.0244302
Bryony Hobden, Peter Ashwin, Paul D L Ritchie
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引用次数: 0

摘要

Dansgaard-Oeschger事件是北大西洋地区在末次冰期发生的突然和不规则变暖。这些事件的一个关键特征是迅速转变为较暖的条件(间日),随后缓慢冷却到较冷的气候(间日),导致区域代用温度记录呈锯齿状。这些事件在过去10万年中多次发生,据推测是由各种机制造成的,包括海洋环流的千年变率和/或海洋环流与其他过程之间的非线性相互作用。我们的出发点是一个非自治的、概念性的、但基于过程的Boers等人的模型。[j] .自然科学进展,2016,(1):1 - 2。该模型可以在一定程度上再现Dansgaard-Oeschger事件的形状、幅度和频率。然而,Boers等人的模型在跨越阈值时具有不同海冰演化机制之间的瞬时切换,因此无法显示这些变暖事件发生或抵消的早期预警信号。在本文中,我们通过加入一个快速动态变量来正则化该模型,使切换在有限时间内平稳进行。这意味着该模型有可能显示出突然变化的早期预警信号。然而,额外的快速时间尺度意味着这些早期预警信号的时间范围可能很短。尽管如此,我们还是发现了模型在缓慢冷却和快速冷却之间转变的一些早期预警证据。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Regularization of a conceptual model for Dansgaard-Oeschger events.

The Dansgaard-Oeschger events are sudden and irregular warmings of the North Atlantic region that occurred during the last glacial period. A key characteristic of these events is a rapid shift to warmer conditions (interstadial), followed by a slower cooling toward a colder climate (stadial), resulting in a saw-tooth pattern in regional proxy temperature records. These events occurred many times during the last 100 000 years and have been hypothesized to result from various mechanisms, including millennial variability of the ocean circulation and/or nonlinear interactions between ocean circulation and other processes. Our starting point is a non-autonomous, conceptual, but process-based, model of Boers et al. [Proc. Natl. Acad. Sci. 115, E11005-E11014 (2018)] that includes a slowly varying non-autonomous forcing represented by reconstructed global mean temperatures. This model can reproduce Dansgaard-Oeschger events in terms of shape, amplitude, and frequency to a reasonable degree. However, the model of Boers et al. has instantaneous switches between different sea-ice evolution mechanisms on crossing thresholds and, therefore, cannot show early warning signals of the onset or offset of these warming events. In this paper, we regularize this model by adding a fast dynamic variable so that the switching occurs smoothly and in finite time. This means the model has the potential to show early warning signals for sudden changes. However, the additional fast timescale means these early warning signals may have short time horizons. Nonetheless, we find some evidence of early warning for the transition between slow and rapid cooling for the model.

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来源期刊
Chaos
Chaos 物理-物理:数学物理
CiteScore
5.20
自引率
13.80%
发文量
448
审稿时长
2.3 months
期刊介绍: Chaos: An Interdisciplinary Journal of Nonlinear Science is a peer-reviewed journal devoted to increasing the understanding of nonlinear phenomena and describing the manifestations in a manner comprehensible to researchers from a broad spectrum of disciplines.
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