Using Electrical Conductance Measurements to Develop the South Pole Ice Core Chronology

冰芯记录了过去气候变化的详细历史。南极冰芯将允许对大气微量气体进行调查，并填补了解南极洲气候变化模式的重要空白。对冰芯记录的解释来说，一个准确的时间标度是至关重要的，它可以给冰芯中每个深度的冰指定一个年龄。这项工作将使用电学方法，通过检测冰层中火山杂质导致的这些层的电导率增强，来识别过去~4万年来核心地区的火山爆发。这些喷发将与南极洲其他冰芯的模式相匹配，使冰芯之间气候变化的时间同步，并允许将为其他南极冰芯开发的精确时间尺度转移到南极冰芯。火山作用的准确年代记录将与大气气体、稳定的水同位素和气溶胶的记录相结合，以更好地了解过去4万年中巨大的自然气候变化。电导法和介电剖面测量将在国家冰芯实验室沿着南极冰芯的每个部分的长度进行。这些测量将有助于为地核建立一个时间表。电测量将为整个岩心提供火山事件的连续记录，包括通过脆性冰（550-1250m代表~10,000-20,000年的冰），岩心质量和薄的年层可能会阻止连续融化分析，导致离散测量错过火山事件。电测量还在每个芯的纵向切割表面上产生电层的二维图像。这些数据将用于识别任何不规则或缺失的分层，这将表明岩心中存在地层扰动。一个可靠的年代学对于解释南极冰芯的古气候记录至关重要。研究人员将通过与国家科学教师协会的会谈和网络研讨会吸引教师，并将在太平洋科学中心的极地科学周末等活动中与公众分享信息。结果将通过出版物和会议发言传播，数据将存档并公开提供。

Ice cores record detailed histories of past climate variations. The South Pole ice core will allow investigation of atmospheric trace gases and fill an important gap in understanding the pattern of climate variability across Antarctica. An accurate timescale that assigns an age to the ice at each depth in the core is essential to interpretation of the ice-core records. This work will use electrical methods to identify volcanic eruptions throughout the past ~40,000 years in the core by detecting the enhanced electrical conductance in those layers due to volcanic impurities in the ice. These eruptions will be pattern-matched to other cores across Antarctica, synchronizing the timing of climate variations among cores and allowing the precise timescales developed for other Antarctic ice cores to be transferred to the South Pole ice core. The well-dated records of volcanic forcing will be combined with records of atmospheric gases, stable water-isotopes, and aerosols to better understand the large natural climate variations of the past 40,000 years. The electrical conductance method and dielectric profiling measurements will be made along the length of each section of the South Pole ice core at the National Ice Core Lab. These measurements will help to establish a timescale for the core. Electrical measurements will provide a continuous record of volcanic events for the entire core including through the brittle ice (550-1250m representing ~10,000-20,000 year-old ice) where the core quality and thin annual layers may prevent continuous melt analysis and cause discrete measurements to miss volcanic events. The electrical measurements also produce a 2-D image of the electrical layering on a longitudinal cut surface of each core. These data will be used to identify any irregular or absent layering that would indicate a stratigraphic disturbance in the core. A robust chronology is essential to interpretation of the paleoclimate records from the South Pole ice core. The investigators will engage teachers through talks and webinars with the National Science Teachers Association and will share information with the public at events such as Polar Science Weekend at the Pacific Science Center. Results will be disseminated through publications and conference presentations and the data will be archived and publicly available.