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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=595081
• 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.

在过去的一个世纪里，地磁场发生了巨大的变化。北极磁极(NMP)位置的变化和偶极磁场(即地球磁场的主要组成部分)的迅速下降最能说明这一点。NMP在历史时期仅限于加拿大北极地区，最近已转移到北冰洋。直接观测表明，自20世纪70年代初的S以来，北冰洋的迁移速度急剧增加，从9公里/年增加到41公里/年，2003年又增加到近60公里/年，而在解决湾地磁观测站测得的强度的年变化率在过去50年里从大约10 nT/年增加到近70 nT/年。这些壮观的变化导致了下列问题的提出：我们是否处于大规模地磁变化的初始阶段，甚至是逆转？如果是这样的话，“大规模地磁变化的原因(在地球核心)和后果(对地球环境)是什么？”要回答这些基本问题，历史记录必须首先放在更长的地质背景下。因此，这一研究计划的长期目标是确定第四纪晚期地磁场的高频动力学，特别强调突变及其对气候的可能影响。这项研究计划将在北极地区提供第一个大规模的地磁场动力学研究。此外，通过选择沉积物积累率非常高的取心地点，拟议的研究将调查刚刚开始探索的时间分辨率的地磁场变异性，即百年至千年的时间尺度。这些观测将：1)能够检验从历史地磁记录中发展出来的假说；2)为地球发电机模型提供宝贵的数据；3)将当前NMP的戏剧性崩塌和迁移置于详细的地质背景中。最后，在气候快速变化之际，由于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，探索气候变化和地磁场形态之间的潜在联系值得特别关注。