Solar influences on climate during the last and penultimate glacial

太阳是地球气候系统的主要能源。在整个11年的太阳“施瓦贝”周期中，太阳总辐照度变化约为1 W m-2。尽管有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型结果都表明，太阳对气候的影响是巨大的，其时间尺度从几年到几千年不等，并受到气候强迫和边界条件的复杂相互作用的影响。尽管信息多种多样，但对太阳与气候之间联系的全面了解仍然有限。主要原因是现有的太阳-气候研究几乎只局限于气候稳定的全新世，宇宙成因的放射性核素如10 Be和14 C是由入射的银河宇宙射线在地球高层大气中产生的。这些同位素的产生率反过来又受到太阳和地磁对银河宇宙射线的不同屏蔽的影响。因此，10 Be和14 C储存在自然环境档案中，提供了太阳变化和地球磁场强度的替代记录。近几十年来，从树木和冰芯中定期测量宇宙成因放射性核素记录。 然而，这些档案并不携带古地磁信号，增加了现有的太阳变化重建的不确定性。此外，来自树木的14 C记录仅限于过去14000年，冰芯10 Be时间序列由于横向冰流而失去时间分辨率。沉积物记录可以提供两个独立的记录，10 Be生产和地磁场强度远到过去，而不会失去时间分辨率。在这个建议中，我们的目标是建立新的代理记录的太阳能变化应用配对10 Be和paleointensity测量黑海沉积物在40年的分辨率的最后一次和倒数第二次冰期的部分。我们将提供第一个10 Be记录从海洋沉积物中的一个足够的分辨率，为几十年的太阳变率重建。一个多层次的方法，包括（1）回归分析与代理记录，（2）模拟10 Be的古强度数据和（3）9 Be归一化，所有来自相同的黑海沉积物岩心，以及（4）多放射性核素记录比较，将使我们能够区分太阳从地磁和环境对10 Be沉积的影响。研究的最终目标是调查太阳对气候的影响，在完整的末次冰期最大条件（22-28 ka BP），一个时期的明显Dansgaard-Oeschger变化（40-55 ka BP）和终端II（128-134 ka BP），基于我们的新的太阳变化记录与直接从黑海沉积物和从周围的地球仪的古气候时间序列的系统比较。这项工作将提高我们对太阳-气候联系的空间和时间模式的认识，并使我们能够更好地预测太阳在人类世纪气候变化中的作用。

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.