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。南极冰芯将允许调查大气中的微量气体，并填补了解南极洲气候变化模式的重要空白。准确的时间尺度可以为冰芯每个深度的冰指定年龄，这对于解释冰芯记录至关重要。这项工作将使用电学方法，通过检测由于冰中火山杂质而增强的这些层的电导率，来识别过去约 40,000 年的火山喷发。这些喷发将与南极洲的其他冰芯进行模式匹配，同步各冰芯之间气候变化的时间，并允许为其他南极冰芯开发的精确时间尺度转移到南极冰芯。火山强迫的过时记录将与大气气体、稳定水同位素和气溶胶的记录相结合，以更好地了解过去 4 万年的巨大自然气候变化。 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每个部分的长度进行。 这些测量将有助于确定核心的时间表。电测量将为整个核心提供火山事件的连续记录，包括通过脆性冰（550-1250m代表约10,000-20,000年的冰），其中核心质量和薄年层可能会妨碍连续的融化分析并导致离散测量错过火山事件。电气测量还产生每个芯的纵向切割表面上的电气分层的二维图像。这些数据将用于识别任何不规则或不存在的分层，这表明岩心存在地层扰动。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与教师互动，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演示传播，数据将存档并公开。

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.