Solar Activity during the Last Millennium, Estimated from Cosmogenic in-situ 14C in South Pole and GISP2 Ice Cores

这个奖项支持一个项目继续发展估算过去太阳活动的新方法。它是根据宇宙射线对极地冰中原位产生的C-14浓度的测量得出的，这仅取决于(i)宇宙射线通量和（ii）冰积累速率。这是确定极地冰年代的唯一直接方法，因为它不涉及任何不确定的气候传递函数，而在树木年轮中的宇宙成因C-14数据或冰和沉积物中的Be-10数据的应用中则遇到这种情况。一项重要的任务是提高过去32凯尔太阳活动高/低时期的时间分辨率。该计划是对过去一千年（公元1100-1825年）宇宙射线通量的变化进行研究，在此期间，从历史记录中确定了4个太阳活动低潮期和1个太阳活动高峰期。这些时期的大部分太阳黑子数据是稀疏的。从南极和格陵兰峰顶的冰芯中可以获得足够的冰样本，并将对这一时期过去的太阳活动水平进行仔细的高分辨率研究。这项工作的智力价值包括从宇宙射线通量的两个极地冰记录中对估计的太阳活动水平提供独立的验证，并大大提高了我们对日地关系的理解。更广泛的影响包括与其他科学家合作，他们是大气宇宙成因C-14应用方面的专家，以及学生培训。本科生和研究生都将参与拟议的研究。还将利用各种形式的外联来传播该项目的成果，包括公开介绍和与媒体的互动。

0538683LalThis award supports a project to continue development of a new method for estimating solar activity in the past. It is based on measurements of the concentrations of in-situ produced C-14 in polar ice by cosmic rays, which depend only on (i) the cosmic ray flux, and (ii) ice accumulation rate. This is the only direct method available to date polar ice, since it does not involve any uncertain climatic transfer functions as are encountered in the applications of cosmogenic C-14 data in tree rings, or of Be-10 in ice and sediments. An important task is to improve on the temporal resolution during identified periods of high/low solar activity in the past 32 Kyr. The plan is to undertake a study of changes in the cosmic ray flux during the last millennium (1100-1825 A.D.), during which time 4 low and 1 high solar activity epoch has been identified from historical records. Sunspot data during most of these periods are sparse. Adequate ice samples are available from ice cores from the South Pole and from Summit, Greenland and a careful high resolution study of past solar activity levels during this period will be undertaken. The intellectual merit of the work includes providing independent verification of estimated solar activity levels from the two polar ice records of cosmic ray flux and greatly improve our understanding of solar-terrestrial relationships. The broader impacts include collaboration with other scientists who are experts in the application of the atmospheric cosmogenic C-14 and student training. Both undergraduates and a graduate student will be involved in the proposed research. Various forms of outreach will also be used to disseminate the results of this project, including public presentations and interactions with the media.