Solar influences on climate during the last and penultimate glacial

太阳是地球气候系统的主要能源。在11年的太阳“施瓦贝”周期中，太阳总辐照度变化约为1w - m-2。尽管存在这种微小的能量变化，但大量的气象观测、古气候重建和气候模式结果表明，太阳对气候的影响很大，时间尺度从数年到数千年不等，受到气候强迫和边界条件复杂相互作用的影响。尽管信息的多样性，对太阳-气候关系的全面认识仍然有限。主要原因是现有的太阳气候研究几乎完全局限于气候相对稳定的全新世。像10Be和14C这样的宇宙放射性核素是由银河系宇宙射线入射到地球上层大气中产生的。这些同位素的产生速率，反过来，被改变太阳和地磁屏蔽星系宇宙射线。因此，沉积在自然环境档案中的10Be和14C提供了太阳变率和地球磁场强度的代用记录。在最近的几十年里，从树木和冰芯中定期测量宇宙形成的放射性核素记录。然而，这些档案不携带古磁信号，增加了现有太阳变率重建的不确定性。此外，来自树木的准确的14C记录仅限于过去14000年，而冰芯10Be时间序列由于侧向冰流而失去了时间分辨率。沉积物记录可以提供远至过去的10Be产量和地磁场强度的独立记录，而不会失去时间分辨率。在这个提议中，我们的目标是建立新的太阳变率的代理记录，应用配对的10Be和古强度测量从黑海沉积物在40年的分辨率，为最后一个和第二个冰期的部分。我们将以足够的分辨率提供来自海洋沉积物的第一个10Be记录，用于多年代际太阳变率的重建。采用多层方法，包括：(1)代记录回归分析，(2)古强度数据模拟10Be， (3) 9Be归一化，所有这些都来自同一黑海沉积物岩心，以及(4)多放射性核素记录比较，将使我们能够区分太阳、地磁和环境对10Be沉积的影响。本研究的最终目标是通过将我们的新太阳变率记录与直接来自黑海沉积物和全球各地的古气候时间序列进行系统比较，研究末次冰期（22-28 ka BP）的太阳对气候的影响，这是一个明显的Dansgaard-Oeschger变率（40-55 ka BP）和终止期（128-134 ka BP）。这项工作将提高我们对太阳-气候联系的时空模式的认识，并使我们能够更好地预测太阳在21世纪人为气候变化中的作用。

The Sun is the main energy source of Earth’s climate system. Total solar irradiance varies by ~1 W m-2 throughout the 11-year solar ‘Schwabe’ cycle. Regardless of this small energetic change, numerous meteorological observations, paleoclimate reconstructions and climate model results point to substantial solar influences on climate, on time-scales from years to millennia, modified by a complex interplay of climate forcings and boundary conditions. Despite the diversity of information, a comprehensive understanding of Sun-climate linkages is still limited. Main cause is the nearly exclusive limitation of existing Sun-climate studies to the climatologically comparably stable Holocene.Cosmogenic radionuclides like 10Be and 14C are produced in Earth’s upper atmosphere by incident galactic cosmic rays. The production rate of these isotopes is, in turn, modified by varying solar and geomagnetic shielding of galactic cosmic rays. Therefore, deposited in natural environmental archives, 10Be and 14C provide proxy records of both solar variability and Earth’s magnetic field strength. During the recent decades cosmogenic radionuclide records were routinely measured from trees and ice cores. However, these archives do not carry a paleomagnetic signal, adding uncertainty to existing solar variability reconstructions. Moreover, well-dated 14C records from trees are limited to the last 14000 years and ice core 10Be time-series lose temporal resolution back in time due to lateral ice flow. Sediment records can provide independent records of both, 10Be production and geomagnetic field strength far into the past, without losing temporal resolution. Within this proposal, we aim at establishing novel proxy records of solar variability applying paired 10Be and paleointensity measurements from Black Sea sediments at 40-year resolution for parts of the last and penultimate glacial. We will provide the first 10Be records from marine sediments at a sufficient resolution for multi-decadal solar variability reconstruction. A multi-layer approach including (1) regression analysis with proxy records, (2) modelled 10Be from paleointensity data and (3) 9Be normalization, all from the same Black Sea sediment cores, as well as (4) multi-radionuclide record comparisons will allow us to distinguish solar from geomagnetic and environmental effects on 10Be deposition. Ultimate goal of the research is the investigation of solar influences on climate during full Last Glacial Maximum conditions (22-28 ka BP), a period of distinct Dansgaard-Oeschger variability (40-55 ka BP) and Termination II (128-134 ka BP), based on systematic comparisons of our novel solar variability records with paleoclimate time-series directly from Black Sea sediments and from around the globe. The work will improve our knowledge about spatial and temporal patterns of Sun-climate linkages and allow us to better anticipate Sun’s role within the anthropogenic 21st century climate change.