Interhemispheric high-frequency geomagnetic field dynamics

半球间高频地磁场动力学

• 批准号: RGPIN-2017-05294
• 负责人: StOnge, Guillaume
• 金额: $ 3.42万
• 依托单位: Université du Québec à Rimouski
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765292
• 关键词: Interhemispheric; frequency; geomagnetic; field; dynamics

Recent direct observations have demonstrated that the geomagnetic field has undergone dramatic changes over the last century. This is best illustrated by changes in the position of the North Magnetic Pole (NMP) and the rapid decline of the dipole field (i.e, the main component of Earth's magnetic field). The NMP, restricted to the Canadian Arctic during historical times (last 400 yrs), has recently moved into the Arctic Ocean. Direct observations reveal that the migration of the NMP has increased dramatically since the early 1970's from 9 km/yr to 41 km/yr and to almost 60 km/yr in 2003, whereas the annual rate of change in intensity measured at the Resolute Bay geomagnetic observatory has increased from about 10 nT/yr to almost 70 nT/yr over the last 50 years. In addition, the recent migration of the NMP occurs between two important areas of observed geomagnetic fluxes in North America and Siberia. The role of these geomagnetic flux lobes in driving Holocene geomagnetic variability is currently unknown, but maybe key. Similarly, recent satellite observations in the Southern Hemisphere and geomagnetic models reveal an important magnetic anomaly developed over the last centuries in the Southern Hemisphere. The origin and cause of this anomaly, named the South Atlantic Magnetic Anomaly are still unknown. These recent spectacular changes lead to the formulation of the following questions: “Are we in the initial stages of a large-scale geomagnetic change, or even a reversal?” and “are these changes associated with the dynamics of flux lobes?”. To answer these fundamental questions, the historical record must first be placed into a longer geological context. The long-term goal of my Discovery Grant program is to determine the high frequency dynamics of the geomagnetic field during the Late Quaternary with a special emphasis on abrupt changes in the high latitudes of both hemispheres. This research program will provide the first large-scale Holocene interhemispheric study of high latitude geomagnetic field dynamics. In addition, by selecting coring sites with very high sediment accumulation rates, the proposed research will investigate geomagnetic field variability at a temporal resolution that is just beginning to be explored, the centennial to millennial timescales. These observations will: 1) enable testing of hypotheses developed from the historical geomagnetic record, 2) yield invaluable data for geodynamo modelling, and 3) place the current dramatic collapse and migration of the NMP into a detailed geological context. The proposed research will also provide novel data to enhance our understanding of Sun/Earth interactions, as the combination of paleomagnetic and 10Be analysis from the same cores will help decipher the influence of the geomagnetic field on the production rate of cosmogenic isotopes, with practical implications for dating, space weather, telecommunications and climate.

最近的直接观察表明，地磁领域在上个世纪发生了巨大的变化。最好通过北磁极（NMP）位置的变化和偶极场快速下降（即地球磁场的主要成分）的快速下降来说明这一点。 NMP在历史时期（最后400年）仅限于加拿大北极，最近进入了北极海洋。直接观察结果表明，自1970年代初以来，NMP的迁移已从9 km/yr开始急剧增加到41 km/yr，到2003年的近60 km/yr，而在Resolute Bay GeoMagnetic观测值中测得的年度强度变化率从大约10 nt/yr增加到了几乎10 nt/yr，而终于50 nt/yr升高到几乎70 nt/yr。此外，NMP最近的迁移发生在北美和西伯利亚观察到的地磁通量的两个重要领域。这些地磁通量在驱动全新世的地磁变异性中的作用目前尚不清楚，但也许是关键。同样，南半球和地磁模型的最新卫星观测表明，在南半球过去几个世纪中发生了重要的磁异常。这种异常的起源和原因，称为南大西洋磁异常，仍然未知。这些最近的壮观变化导致了以下问题的公式：“我们是否处于大规模地磁变化的初始阶段，甚至是反向？”和“这些变化与通量爱的动态有关吗？”。为了回答这些基本问题，必须首先将历史记录置于更长的地质环境中。我的发现赠款计划的长期目标是确定晚期晚期时地磁场的高频动力学，特别强调了两个半球高纬度的突然变化。该研究计划将提供第一个大尺度全新世间跨层间研究，对高纬度地磁场动力学。此外，通过选择具有很高沉积物累积速率的芯场，拟议的研究将研究刚刚开始探索的临时分辨率的地磁场变异性，这是对千年时间表的百年纪念。这些观察结果将：1）能够测试从历史地磁记录中开发的假设，2）对地磁建模产生宝贵的数据，以及3）将当前的NMP剧烈崩溃和迁移到详细的地质环境中。拟议的研究还将提供新的数据，以增强我们对太阳相互作用的理解，因为从同一核心的古磁和10BE分析的组合将有助于解读地磁领域对宇宙同位素生产速率的影响，以及对约会，太空，太空，远程通讯和气候的实际意义。