A simple conceptual model of abrupt glacial climate events
A simple conceptual model of abrupt glacial climate events
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DOI：
10.5194/npg-14-709-2007
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发表时间：
2007-01-01
影响因子：
2.2
通讯作者：
Chialvo, D. R.
中科院分区：
文献类型：
--
作者：
Braun, H.;Ganopolski, A.;Chialvo, D. R.
在这里，我们使用一个非常简单的概念模型，试图减少冰川气候突变的复杂非线性的重要部分（所谓的Dansgaard-Oeschger事件）的几个简单的原则，即（i）存在两种不同的气候状态，（ii）阈值过程和（iii）在事件开始和结束时系统稳定性的过冲，然后是千年一遇的放松通过比较与所谓的地球系统模型的中间复杂性（CLIMBER-2），其中的事件代表两个气候状态之间的振荡对应于两个根本不同的模式，在北大西洋深水形成，我们表明，概念模型捕捉的基本方面的非线性事件在该模型中。我们使用的概念模型，以再现和重新分析非线性共振机制，已经建议，以解释的特征时间尺度的Dansgaard-Oeschger事件。在这样做，我们确定了一种新形式的随机共振（即过冲随机共振），并提供了第一个明确报告的表现，鬼共振在一个地理系统，即一个机制，这可能是相关的其他系统的阈值和多个状态的操作。我们的工作使我们能够明确地模拟现实的概率措施的Dansgaard-Oeschger事件（例如等待时间分布，这是一个先决条件，通过蒙特-卡罗模拟的事件的规律性进行统计分析）。因此，我们认为，我们的研究是一个重要的进步，以开发更充分的方法来测试统计意义和拟议的冰川1470年气候周期的起源。
Here we use a very simple conceptual model in an attempt to reduce essential parts of the complex nonlinearity of abrupt glacial climate changes (the so-called Dansgaard-Oeschger events) to a few simple principles, namely (i) the existence of two different climate states, (ii) a threshold process and (iii) an overshooting in the stability of the system at the start and the end of the events, which is followed by a millennial-scale relaxation. By comparison with a so-called Earth system model of intermediate complexity (CLIMBER-2), in which the events represent oscillations between two climate states corresponding to two fundamentally different modes of deep-water formation in the North Atlantic, we demonstrate that the conceptual model captures fundamental aspects of the nonlinearity of the events in that model. We use the conceptual model in order to reproduce and reanalyse nonlinear resonance mechanisms that were already suggested in order to explain the characteristic time scale of Dansgaard-Oeschger events. In doing so we identify a new form of stochastic resonance (i.e. an overshooting stochastic resonance) and provide the first explicitly reported manifestation of ghost resonance in a geosystem, i.e. of a mechanism which could be relevant for other systems with thresholds and with multiple states of operation. Our work enables us to explicitly simulate realistic probability measures of Dansgaard-Oeschger events (e.g. waiting time distributions, which are a prerequisite for statistical analyses on the regularity of the events by means of Monte-Carlo simulations). We thus think that our study is an important advance in order to develop more adequate methods to test the statistical significance and the origin of the proposed glacial 1470-year climate cycle.