Late Quaternary geomagnetic field dynamics and abrupt changes

晚第四纪地磁场动力学和突变

• 批准号: 312343-2012
• 负责人: StOnge, Guillaume
• 金额: $ 3.93万
• 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: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=526473
• 关键词: Late; Quaternary; geomagnetic; field; dynamics

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, 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. These 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 if so, "What are the causes (in Earth's core) and consequences (to Earth's environment) of a large scale geomagnetic change?" To answer these fundamental questions,the historical record must first be placed into a longer geological context. The long-term goal of this research program is thus to determine the high frequency dynamics of the geomagnetic field during the Late Quaternary with a special emphasis on abrupt changes and their possible influence on climate. This research program will provide the first large-scale study of geomagnetic field dynamics in the Arctic. 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. Finally, exploring the potential linkages between climate change and geomagnetic field morphology deserves special attention at this time of rapid climatic change as no current numerical climate model accounts for the possible influence of cosmic rays or the geomagnetic field on climate.

地磁场在上个世纪经历了巨大的变化。北磁极（NMP）位置的变化和偶极子场（即地球磁场的主要组成部分）的迅速减弱最能说明这一点。NMP在历史上仅限于加拿大北极地区，最近已经进入北冰洋。直接观测表明，自20世纪70年代初以来，NMP的迁移急剧增加，从9 km/年增加到41 km/年，2003年增加到近60 km/年，而在过去50年中，Resolute湾地磁观测站测量的强度年变化率从约10 nT/年增加到近70 nT/年。这些惊人的变化导致了以下问题的形成：“我们是否处于大规模地磁变化的初始阶段，甚至是逆转？”如果是这样，“大规模地磁变化的原因（在地核中）和后果（对地球环境）是什么？”要回答这些基本问题，必须首先把历史记录放在一个更长的地质背景中。因此，本研究项目的长期目标是确定晚第四纪地磁场的高频动态，特别强调突变及其对气候的可能影响。该研究项目将首次对北极地磁场动力学进行大规模研究。此外，通过选择沉积物堆积率非常高的取心地点，拟议的研究将以刚刚开始探索的时间分辨率（百年至千年时间尺度）调查地磁场的变化。这些观察结果将：1)能够检验从历史地磁记录中发展出来的假设，2)为地球动力学建模提供宝贵的数据，3)将当前NMP的剧烈崩塌和迁移置于详细的地质背景中。最后，在这个气候快速变化的时代，探索气候变化与地磁场形态之间的潜在联系值得特别关注，因为目前没有数值气候模式考虑宇宙射线或地磁场对气候的可能影响。