Reconstructing solar activity and geomagnetic field intensity during the Holocene

太阳是地球气候系统最重要的能源。过去四个世纪的直接观测表明，太阳活动随着时间的推移而变化，这些变化似乎在前工业时代的地球气候变化中发挥了重要作用，例如中世纪温暖期（公元900-1400年）。小冰河时期（1500-1800 A.D.）过去11，500年（全新世时期）太阳活动的长期变化及其与气候变化的潜在联系仍然非常不确定。宇宙成因的核素，如10 Be和14 C，在大气中的生产是由太阳活动控制的，这意味着这些核素的记录从自然档案可以扩展我们的知识太阳变化的时间。然而，重建过去的太阳活动是复杂的，因为嵌入自然档案中的10 Be和14 C信号也受到地球磁场强度和当地气候效应的影响。因此，目前重建过去太阳活动的努力受到重建过去地磁场强度的不确定性和高分辨率10 Be和14 C记录的有限性的阻碍。长期太阳变化仍然是一个非常有争议的话题，有一个替代宇宙成因核素记录来解决这个问题的巨大需求。有了这个建议，我将采取一种新的方法，以提高目前的理解，太阳的变化在全新世期间，从不同的档案产生新的高分辨率记录过去10 Be生产率结合分析过去的变化，在地球磁场的强度。该项目的主要重点将是产生一个高分辨率的10 Be记录从每年分层（纹）湖沉积物从中西部瑞典。我建议研究的沉积物岩心的年度叠层提供了极好的年代控制，以及确定过去9,500年地球表面10 Be通量的独特机会。我还将开发一个高分辨率的10 Be记录全新世海洋沉积物在遥远的北大西洋。基于相同的海洋沉积物，我还将生成过去11 500年期间地磁场行为的新的极高分辨率记录。我以前的研究表明，冰岛南部这个地方的沉积物非常适合详细研究10 Be生产率和地磁强度的变化。该项目的另一个方面将是探索过去10 Be沉积的其他档案。我希望集中讨论的小说档案包括一个来自N.爱尔兰和中国中部一个洞穴的石笋。结合新的10 Be记录从这项研究与现有的10 Be记录从极地冰芯，将有可能过滤出当地的气候影响嵌入在个人的记录，并产生一个全球记录的全新世变化的10 Be生产率。同样，将把新的高分辨率地磁场行为记录与现有的磁力数据结合起来，对全新世地磁场强度作出全球估计。通过对10 Be组合曲线进行地球磁场强度变化的校正，有可能重建全新世期间的太阳活动。通过将新的全球10 Be记录与现有的14 C记录进行比较，还可以评估全新世期间碳循环的潜在变化。

The Sun is by far the most important energy source for the Earth's climate system. Direct observations over the last four centuries have revealed that solar activity varies over time, and these variations appear to have played a significant role in forcing periods of climate change on Earth in the pre-industrial era, such as the Medieval Warm Period (900-1400 A.D.) and the Little Ice Age (1500-1800 A.D.). The longer-term variations in solar activity over the last 11,500 years (the Holocene period), and their potential links to climate change, remain very uncertain. The production of cosmogenic nuclides, such as 10Be and 14C, in the atmosphere is controlled by solar activity, implying that records of such nuclides from natural archives may extend our knowledge of solar variation back in time. Reconstruction of past solar activity is complicated, however, by the fact that the 10Be and 14C signals embedded in natural archives are also influenced by the intensity of Earth's magnetic field and by local climatic effects. Current efforts to reconstruct past solar activity are, therefore, hampered by uncertainties in reconstructing past geomagnetic field intensity and the limited availability of high-resolution 10Be and 14C records. The long-term solar variability remains a very controversial topic and there is a great need for alternative cosmogenic nuclide records to address this issue. With this proposal I will take a new approach to improve the current understanding of solar variability during the Holocene by generating new high-resolution records from different archives of past 10Be production rates combined with analyses of past variations in the intensity of the Earth's magnetic field. The main focus of this project will be to generate a high-resolution 10Be record from annually-layered (varved) lake sediments from west-central Sweden. The annual laminations of the sediment core I propose to study provide excellent chronological control, and a unique opportunity for determining the flux of 10Be to the surface of the Earth for the past 9,500 years. I will also develop a high-resolution 10Be record for the Holocene from marine sediments in the far North Atlantic. Based on the same marine sediments, I will also generate new extremely high-resolution records of the geomagnetic field behaviour during the past 11,500 years. My previous research has shown that the sediments from this location south of Iceland are well-suited for detailed studies of variations in 10Be production rates and geomagnetic intensity. Another aspect of this project will be to explore other archives of past 10Be deposition. The novel archives I wish to concentrate on include a raised peat bog from N. Ireland and a stalagmite from a cave in central China. Combining the new 10Be records from this study with existing 10Be records from polar ice cores, will make it possible to filter out local climatic effects embedded in the individual records and produce a global record of Holocene variations in 10Be production rate. Similarly, the new high-resolution records of the geomagnetic field behaviour will be integrated with existing magnetic data to produce a global estimate of Holocene geomagnetic field intensity. By correcting the combined 10Be curve for variations in the intensity of Earth's magnetic field, it is possible to reconstruct the solar activity during the Holocene. It will also be possible to assess potential changes in the carbon cycle during the Holocene by comparing the new global 10Be record with existing 14C records.