Simulated millennial-scale climate variability driven by a convection-advection oscillator.

IF 3.8 2区 地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES
Climate Dynamics Pub Date : 2025-01-01 Epub Date: 2025-03-07 DOI:10.1007/s00382-025-07630-x
Yvan M Romé, Ruza F Ivanovic, Lauren J Gregoire, Didier Swingedouw, Sam Sherriff-Tadano, Reyk Börner
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引用次数: 0

Abstract

The last glacial period, between around 115 and 12 thousand years before present, exhibited strong millennial-scale climate variability. This includes abrupt transitions between cold and warm climates, known as Dansgaard-Oeschger (D-O) cycles. D-O cycles have been linked to switches in dynamical regimes of the Atlantic Overturning Meridional Circulation (AMOC), but the exact mechanisms behind abrupt climate changes and AMOC regime shifts remain poorly understood. This paper introduces the convection-advection oscillator mechanism to explain the millennial-scale oscillations observed in a set of HadCM3 general circulation model simulations forced with snapshots of deglacial meltwater history. The oscillator can be separated into two components acting on different time scales. The fast convection component responds to changes in vertical stratification in the North Atlantic by activating or deactivating deep water formation sites. The slow advection component regulates the accumulation and depletion of salinity in the North Atlantic. This oscillator mechanism is triggered under specific background conditions and freshwater release patterns. The freshwater perturbation causes an instability that triggers a global salt reorganisation, modifying the North Atlantic stratification. For a given forcing pattern, the system oscillates if the salt transport can lead to an alternating reactivation and deactivation of the AMOC. Otherwise, the climate settles in a warm or cold steady state. This mechanism expands existing theories of millennial-scale variability and provides a general framework for understanding abrupt climate change in general circulation models.

Supplementary information: The online version contains supplementary material available at 10.1007/s00382-025-07630-x.

模拟由对流-平流振荡器驱动的千年尺度气候变率。
在距今约11.5万年至1.2万年之间的末次冰期,表现出强烈的千年尺度气候变率。这包括冷暖气候之间的突变,称为Dansgaard-Oeschger (D-O)循环。D-O循环与大西洋翻转经向环流(AMOC)动力机制的切换有关,但气候突变和AMOC机制转变背后的确切机制仍然知之甚少。本文引入对流-平流振荡机制来解释一组HadCM3环流模式模拟中观测到的千年尺度振荡,这些模拟是由冰川融水历史快照强迫的。振荡器可以分成作用于不同时标的两个分量。快速对流分量通过激活或不激活深水形成点来响应北大西洋垂直分层的变化。缓慢的平流分量调节了北大西洋盐度的积累和消耗。该振荡机制在特定的背景条件和淡水释放模式下触发。淡水扰动导致不稳定,引发全球盐重组,改变北大西洋分层。对于给定的强迫模式,如果盐的输送能够导致AMOC的交替再激活和失活,则系统振荡。否则,气候就会稳定在温暖或寒冷的稳定状态。这一机制扩展了现有的千年尺度变率理论,并为在大气环流模式中理解气候突变提供了一个总体框架。补充信息:在线版本包含补充资料,可在10.1007/s00382-025-07630-x获得。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Climate Dynamics
Climate Dynamics 地学-气象与大气科学
CiteScore
8.80
自引率
15.20%
发文量
483
审稿时长
2-4 weeks
期刊介绍: The international journal Climate Dynamics provides for the publication of high-quality research on all aspects of the dynamics of the global climate system. Coverage includes original paleoclimatic, diagnostic, analytical and numerical modeling research on the structure and behavior of the atmosphere, oceans, cryosphere, biomass and land surface as interacting components of the dynamics of global climate. Contributions are focused on selected aspects of climate dynamics on particular scales of space or time. The journal also publishes reviews and papers emphasizing an integrated view of the physical and biogeochemical processes governing climate and climate change.
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