The effects of long-term changes in the Earth's magnetic field on the atmosphere: understanding the past; predicting the future

地球磁场长期变化对大气的影响：了解过去；

• 批准号: NE/J018058/1
• 负责人: Ingrid Cnossen
• 金额: $ 31.64万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ018058%2F1
• 关键词: effects; long; term; changes; Earth

"The effects of long-term changes in the Earth's magnetic field on the atmosphere: understanding the past; predicting the future"This project investigates the effects of changes in the Earth's internal magnetic field on the atmosphere and climate. The Earth's magnetic field has been changing relatively rapidly in recent times. During the last decade, the position of the north magnetic pole has been moving at its fastest rate recorded so far, at 40-60 km/year. In addition, the magnetic field strength has been steadily decreasing at a rate of 5-7% per century since 1840, which has led to speculations that we may be heading for a magnetic field reversal. Some studies have found correlations between changes in the Earth's magnetic field and climate parameters. However, the responsible mechanism for this link has remained elusive. This project will investigate one possible pathway by which the Earth's magnetic field could affect climate, namely the downward propagation of changes initiated in the upper atmosphere (~100-500 km). This is a novel idea that has not been investigated before.Changes in the Earth's magnetic field directly influence the ionosphere, the charged portion of the upper atmosphere, and the magnetosphere, the bubble around the Earth that shields us from the solar wind. We will examine and quantify the effects of historical changes in the Earth's magnetic field that have occurred since 1600 on the coupled upper atmosphere and magnetosphere system, using simulations with the Coupled Magnetosphere-Ionosphere-Thermosphere (CMIT) model. The responses found will be compared to observed long-term trends in the upper atmosphere and indices of geomagnetic activity, which measure perturbations to the Earth's main magnetic field as a result of ionospheric and magnetospheric current systems. We will also explore some potential future scenarios by extrapolating current magnetic field changes into the next 50-200 years.We then investigate to what extent the effects found in the upper atmosphere influence the middle and lower atmosphere. We will do this using the Whole Atmosphere Community Climate Model (WACCM), a numerical model that extends from the surface to the upper atmosphere, partly overlapping with the CMIT model. At its top, WACCM will be forced with the upper atmospheric responses found in the first part of the project. We will determine whether downward propagation of these forcings causes a significant change in the atmosphere below. Any significant response in the troposphere will be compared to the correlations between magnetic field changes and climate parameters that have been observed.By studying the effects of magnetic field changes on the climate over the past four centuries, this project contributes to a better quantification of natural sources of atmospheric variability. This is needed to attribute observed climate trends correctly and assess man-made effects on climate more precisely. Both are essential for developing mitigation strategies and for making accurate predictions of future climate. The project also offers a first insight into the effects of magnetic field changes that we can expect in the future. Especially a magnetic field reversal would almost certainly have dramatic consequences for the upper atmosphere and geospace environment, and the technological systems this environment hosts. However, the effects on climate are very hard to predict, as we currently do not know in what ways and to what extent the Earth's magnetic field can affect climate. The proposed project will be a first step in improving our understanding of the link between the Earth's magnetic field and climate.

《地球磁场长期变化对大气的影响：了解过去；预测未来》这个项目调查了地球内部磁场变化对大气和气候的影响。近几年来，地球的磁场变化比较快。在过去十年中，北极磁极的位置一直以迄今有记录以来最快的速度移动，达到40-60公里/年。此外，自1840年以来，磁场强度一直以每世纪5%-7%的速度稳步下降，这导致了人们对我们可能正在走向磁场逆转的猜测。一些研究发现，地球磁场的变化与气候参数之间存在相关性。然而，这种联系的负责机制仍然难以捉摸。该项目将研究地球磁场可能影响气候的一种可能途径，即高空大气(约100-500公里)开始的变化向下传播。这是一个以前从未研究过的新概念。地球磁场的变化直接影响电离层，高层大气的带电部分，以及磁层，磁层是地球周围的气泡，保护我们免受太阳风的影响。我们将利用耦合磁层-电离层-热层(CMIT)模型的模拟，研究和量化自1600年以来发生的地球磁场历史变化对高层大气和磁层系统的影响。发现的反应将与观测到的高层大气和地磁活动指数的长期趋势进行比较，地磁活动指数衡量电离层和磁层电流系统对地球主磁场的扰动。我们还将通过外推未来50-200年的电流磁场变化来探索一些潜在的未来情景。然后我们调查在高层大气中发现的效应对中低层大气的影响程度。我们将使用整个大气社区气候模式(WACCM)来实现这一点，这是一个从地表延伸到高层大气的数值模式，与CMIT模式部分重叠。在其顶部，WACCM将被迫使用该项目第一部分中发现的高层大气响应。我们将确定这些强迫的向下传播是否会导致下面的大气发生重大变化。对流层的任何重大响应都将与已观察到的磁场变化和气候参数之间的相关性进行比较。通过研究过去四个世纪磁场变化对气候的影响，该项目有助于更好地量化大气可变性的自然来源。这对于正确归类观测到的气候趋势和更准确地评估人为影响气候是必要的。两者对于制定缓解战略和准确预测未来气候都是必不可少的。该项目还提供了对磁场变化的影响的第一次洞察，这是我们未来可以预期的。特别是磁场反转几乎肯定会对高层大气和地球空间环境以及该环境所拥有的技术系统产生戏剧性的后果。然而，对气候的影响很难预测，因为我们目前不知道地球磁场可以以什么方式和在多大程度上影响气候。拟议中的项目将是提高我们对地球磁场和气候之间联系的理解的第一步。

项目成果

The Impact of Century-Scale Changes in the Core Magnetic Field on External Magnetic Field Contributions

核心磁场百年尺度变化对外部磁场贡献的影响

• DOI: 10.1007/s11214-016-0276-x
• 发表时间: 2016
• 期刊: Space Science Reviews
• 影响因子: 10.3
• 作者: Cnossen I

Upper atmosphere differences between northern and southern high latitudes: The role of magnetic field asymmetry

• DOI: 10.1002/jgra.50554
• 发表时间: 2013-09-01
• 期刊: JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS
• 影响因子: 2.8
• 作者: Foerster, Matthias;Cnossen, Ingrid
• 通讯作者: Cnossen, Ingrid

North-South Asymmetries in Earth's Magnetic Field: Effects on High-Latitude Geospace

地球磁场南北不对称：对高纬度地球空间的影响

• DOI: 10.48550/arxiv.1611.06776
• 发表时间: 2016
• 作者: Laundal K

The role of the Sun in long-term change in the F 2 peak ionosphere: New insights from EEMD and numerical modeling

太阳在 F 2 峰值电离层长期变化中的作用：来自 EEMD 和数值模拟的新见解

• DOI: 10.1002/2014ja020048
• 发表时间: 2014
• 期刊: Space Physics
• 作者: Cnossen I

Investigating Climate Change from the Stratosphere to Space

调查从平流层到太空的气候变化

• DOI: 10.1029/2015eo023767
• 发表时间: 2015
• 期刊: Eos
• 作者: Emmert J