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，并填补在了解整个南极洲气候变化模式方面的一个重要空白。准确的时间刻度是解释冰芯记录的关键，它为冰芯中每个深度的冰分配了一个年龄。这项工作将使用电学方法来识别过去约40,000年来核心的火山喷发，方法是检测由于冰层中的火山杂质而导致这些层中的电导增强。这些喷发将与南极洲其他冰芯的模式相匹配，使各冰芯之间气候变化的时间同步，并使为其他南极冰芯开发的精确时间尺度转移到南极冰芯。准确的火山强迫记录将与大气气体、稳定水同位素和气溶胶的记录相结合，以更好地了解过去40,000年来巨大的自然气候变化。国家冰芯实验室将沿着南极冰芯每一段的长度进行电导法和介电剖面测量。这些测量将有助于建立核心的时间刻度。电学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(550-1250米代表~10,000-20,000年前的冰)，那里的岩心质量和较薄的年层可能会阻止连续的融化分析，并导致离散测量错过火山事件。电学测量还在每个核心的纵向切割表面上产生电学分层的2-D图像。这些数据将被用来识别任何不规则或缺失的分层，这将表明核心存在地层扰动。一个可靠的年表对于解释南极冰芯的古气候记录是必不可少的。调查人员将通过与国家科学教师协会的讲座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进行传播，数据将存档并向公众开放。

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.