近日，瑞典隆德大学教授Nilsson Andreas小组根据全球和半球形的宇宙-射线代理记录推断出了全新世的太阳活动。相关论文于2024年6月21日发表在《自然—地球科学》杂志上。
据研究人员介绍，太阳活动的变化被认为在最近和过去的气候变化中起着重要作用。为了在更长的时间尺度上研究这种联系，有必要知道太阳在过去几千年里是如何变化的。基于太阳黑子数量的太阳变化的直接观测仅限于过去400年，除此之外，以往的研究依赖于宇宙成因放射性核素的记录，如树木年轮和冰芯中的14C和10Be。它们的大气产生率取决于进入银河系的宇宙射线的通量，这是由地球和太阳的磁场调制的，后者与太阳的变化有关。
研究人员表示，考虑到与地磁场不对称有关的半球产量的差异，该研究有助于解决迄今为止在全新世太阳活动重建中无法解释的差异。研究过程中没有发现太阳活动长期变化的令人信服的证据，并表明在千年或更长的时间尺度上，包括2400年的Hallstatt周期，宇宙放射性核素产生率的变化可以用地磁场的变化来解释。研究结果还表明，在全新世期间，偶极矩的平均强度更强，这与南半球更高的磁场强度有关。
附：英文原文
Title: Holocene solar activity inferred from global and hemispherical cosmic-ray proxy records
Author: Nilsson, Andreas, Nguyen, Long, Panovska, Sanja, Herbst, Konstantin, Zheng, Minjie, Suttie, Neil, Muscheler, Raimund
Issue&Volume: 2024-06-21
Abstract: Variations in solar activity have been proposed to play an important role in recent and past climate change. To study this link on longer timescales, it is essential to know how the Sun has varied over the past millennia. Direct observations of solar variability based on sunspot numbers are limited to the past 400 years, and beyond this we rely on records of cosmogenic radionuclides, such as 14C and 10Be in tree rings and ice cores. Their atmospheric production rates depend on the flux of incoming galactic cosmic rays, which is modulated by Earth’s and the Sun’s magnetic fields, the latter being linked to solar variability. Here we show that accounting for differences in hemispherical production rates, related to geomagnetic field asymmetries, helps resolve so far unexplained differences in Holocene solar activity reconstructions. We find no compelling evidence for long-term variations in solar activity and show that variations in cosmogenic radionuclide production rates on millennial timescales and longer, including the 2,400-year Hallstatt cycle, are explained by variations in the geomagnetic field. Our results also suggest an on-average stronger dipole moment during the Holocene, associated with higher field intensities in the Southern Hemisphere.
DOI: 10.1038/s41561-024-01467-5
Source: https://www.nature.com/articles/s41561-024-01467-5