Collaborative Research: A High-sensitivity Beryllium-10 Record from an Ice Core at South Pole

该项目将从南极的冰芯中获取铍-10 （10Be）的浓度测量值。铍元素的一种同位素10Be是由从太空进入地球大气层的高能质子（宇宙射线）在大气中产生的。它通过沉降或被雨或雪清除而从大气中移除。因此，南极雪中10Be的浓度反映了大气中10Be的生成速率。由于在南极上空产生10Be的速率主要取决于太阳磁场的强度，对南极冰芯中10Be的测量将提供太阳活动变化的记录。南极冰芯底部的年龄将达到4万年。该项目将以年分辨率测量过去100年的10Be，以及更遥远的过去的选定时期，如蒙德极小期（17世纪末没有观测到太阳黑子的时期），或大约2万年前的最后一次冰期。一个气候模型可以模拟10Be在大气中的产生，它在大气中的运输，以及它在南极洲雪表面的沉积，这将有助于利用10Be的数据来确定过去从十年到千年尺度的太阳活动的变化，进而评估太阳在地球上的作用。从一个新的角度看待美国的气候。地球大气中铍的产生是由于宇宙射线使大气中的氧和氮碎裂而产生的。宇宙射线在高纬度地区的变化主要是由太阳变率调制的。因此，冰芯10Be的时间序列记录对于推导太阳活动随时间的变化非常重要，这是理解气候变化的基础。10Be在冰表面的沉积也受到大气环流和沉积过程变率的影响，南极是大气环流变化对10Be沉积影响最小的最佳位置。迄今为止，南极只有一个10Be的记录；该记录被广泛用于气候模型中使用的太阳强迫估算，但只涵盖了上一个千年，直到公元1982年。我们将在南极一个1500米长、4万年长的冰芯中获得10个be浓度测量值。这将使现有的记录在时间上进一步向前和向前延伸，与太阳和气候变化的现代仪器记录重叠。高分辨率（一年到两年一次）的测量将在目标感兴趣的区域进行，包括过去100年，蒙德极小期（CE 1650-1715）和末次冰期极大期。这些新数据将与气候模型实验结合使用，其中包括10Be的生产、运输和沉积物理。数据和模型结合起来，将创建一个最新的大气10Be生成和太阳活动的记录。

This project will acquire measurements of the concentration of beryllium-10 (10Be) from an ice core from the South Pole, Antarctica. An isotope of the element beryllium, 10Be, is produced in the atmosphere by high-energy protons (cosmic rays) that enter Earth's atmosphere from space. It is removed from the atmosphere by settling or by scavenging by rain or snowfall. Hence, concentrations of 10Be in snow at the South Pole reflect the production rate of 10Be in the atmosphere. Because the rate of production of 10Be over Antarctica depends primarily on the strength of the Sun's magnetic field, measurements of 10Be in the South Pole ice core will provide a record of changes in solar activity. The South Pole ice core will reach an age of 40,000 years at the bottom. The project will result in measurements of 10Be at annual resolution for the last 100 years and selected periods in the more distant past, such as the Maunder Minimum, a period during the late 17th century during which no sunspots were observed, or the last glacial cold period, about 20,000 years ago. A climate model that can simulate the production of 10Be in the atmosphere, it's transport through the atmosphere, and its deposition at the snow surface in Antarctica will be used to aid in using the 10Be data to determine past changes in solar activity from decadal to millennial scale, and in turn to evaluate the role of the Sun in Earth?s climate from a new perspective.The production of 10Be in Earth's atmosphere results from the spallation of oxygen and nitrogen in the atmosphere by cosmic rays. Cosmic ray variations in the high latitudes are primarily modulated by solar variability. Time-series records of 10Be from ice cores are therefore important for deriving variations in solar activity through time, which is fundamental to understanding climate variability. Deposition of 10Be to the ice surface is also influenced by variability in atmospheric circulation and deposition processes, and South Pole is the best available location for minimizing the influence of variable atmospheric circulation on 10Be deposition. To date, only one record of 10Be exists from South Pole; that record is widely used in solar forcing estimates used in climate models, but covers only the last millennium and ends in CE 1982. We will obtain 10Be concentration measurements in a 1500-m, 40000-year long ice core from the South Pole. This will extend the existing record both further back in time and forward to the present, providing overlap with the modern instrumental record of solar and climate variability. High resolution (annual to biannual) measurements will be made in targeted areas of interest, including the last 100 years, the Maunder Minimum (CE 1650-1715), and the last glacial maximum. The novel data will be used in conjunction with climate model experiments that incorporate 10Be production, transport, and deposition physics. Together, data and modeling will create an updated record of atmospheric 10Be production and hence of solar activity.