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

合作研究：来自南极冰芯的高灵敏度铍 10 记录

• 批准号: 1443144
• 负责人: Eric Steig
• 金额: $ 20.97万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1443144&HistoricalAwards=false
• 关键词: Collaborative; Research; sensitivity; Beryllium; 10

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.

该项目将从南极洲南极冰芯获取铍 10 (10Be) 浓度测量值。 铍元素的同位素 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降雪清除而从大气中去除。 因此，南极雪中 10Be 的浓度反映了大气中 10Be 的生成速率。 由于南极洲上空 10Be 的产生率主要取决于太阳磁场的强度，因此对南极冰芯中 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。 该项目将在过去 100 年和更遥远的过去的选定时期以年分辨率测量 10Be，例如蒙德极小期（17 世纪末没有观测到太阳黑子的时期）或最后一次冰川期时期，大约2万年前。 一个气候模型可以模拟大气中 10Be 的产生、它在大气中的传输以及它在南极洲雪面的沉积，将有助于利用 10Be 数据来确定过去从十年到千年的太阳活动变化地球大气中10Be的产生是由于宇宙射线使大气中的氧和氮散裂而产生的。 高纬度地区的宇宙射线变化主要受太阳变率的调节。因此，冰芯中 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，这对于了解气候变化至关重要。 10Be 在冰表面的沉积也受到大气环流和沉积过程变化的影响，而南极是最小化大气环流变化对 10Be 沉积影响的最佳位置。迄今为止，仅存在一份来自南极的 10Be 记录；该记录广泛用于气候模型中使用的太阳强迫估计，但仅涵盖上个千年并于 CE 1982 年结束。我们将在来自南极的 1500 米长、40000 年长的冰芯中获得 10Be 浓度测量值。 这将把现有记录的时间进一步向前延伸到现在，从而与太阳和气候变化的现代仪器记录重叠。将在感兴趣的目标区域进行高分辨率（每年至半年）测量，包括过去 100 年、蒙德极小期 (CE 1650-1715) 和末次盛冰期。这些新数据将与包含 10Be 生产、传输和沉积物理的气候模型实验结合使用。数据和建模将共同创建大气 10Be 生产的更新记录，从而创建太阳活动的更新记录。