Collaborative Research: Toward Dense Observation of Geothermal Fluxes in Antarctica Via Logistically Light Instrument Deployment

合作研究：通过后勤轻型仪器部署对南极洲地热通量进行密集观测

• 批准号: 1744787
• 负责人: Dale Winebrenner
• 金额: $ 22.83万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-15 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744787&HistoricalAwards=false
• 关键词: Collaborative; Research; Toward; Dense; Observation

Nontechnical AbstractStudies in Antarctica are, at present, severely limited by the costs of placing measurement instruments within and beneath thousands of meters of ice. Our aim is to enable dense, widespread measurement-networks by advancing development of low-cost ice melt probe technology to deploy instruments. Ice melt probes use electrical energy to descend through thick ice with little support structure on the ice surface. We are extending previous technology by using anti-freeze to maintain a partially open melt-hole above a descending probe, deploying as we go a new a new fiber-optic technology to measure ice temperature. Ice temperature measurements will reveal spatial patterns of heat welling up from the Earth beneath the ice, which in turn will contribute greatly to finding ancient ice that contains global climate records, and to understanding how ice flow may raise sea levels. Our immediate objective in this 1-year project is to test and refine our anti-freeze-based method in a 15 meter-tall ice column at the University of Wisconsin, so as to reduce technical risk in future field tests. Technical AbstractThe overarching aim of our development is to enable widespread, spatially dense deployments of instruments within and beneath the Antarctic Ice Sheet for a variety of investigations, beginning with observations of basal temperature and geothermal flux at the base of the ice sheet. Dense, widespread deployment requires logistical costs far below current costs for ice drilling and coring. Our approach is to extend ice melt probe technology (which is inherently light, logistically) to allow the progressive deployment of cable for Distributed Temperature Sensing (DTS) from the ice surface as the probe descends, without greatly increasing logistical costs. Our extension is based on arresting refreezing of the melt-hole above the probe (at a diameter a few times the cable diameter) by injecting anti-freeze - specifically, ethanol at temperature near 0C - a few meters above the probe during descent. After thermal equilibration of the liquid ethanol/water column with the ice, DTS measurements yield the depth-profile of ice sheet temperature, from which basal temperature and (over frozen beds) geothermal flux can be inferred. We have carried out initial trials of our approach in a cold-room laboratory, but field work based only on such small-scale tests may still involve unnecessary risk. We therefore propose further testing at a facility of the Ice Drilling Design and Operations (IDDO) facility in Madison, WI. The new trials will test our approaches to melt-hole control and probe recovery in the taller column, will test cable and cable-tension-management methods more nearly approximating those needed to work on ice sheets, and will demonstrate the Distributed Temperature Sensing in its field configuration.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术性摘要目前，南极洲的研究受到在数千米冰内和冰下放置测量仪器的成本的严重限制。我们的目标是通过推进低成本冰融测头技术的发展来部署仪器，从而实现密集、广泛的测量网络。融冰探头使用电能从厚冰中下降，冰面上几乎没有支撑结构。我们正在扩展以前的技术，使用防冻技术来保持下降探测器上方的部分开放的融化孔，在我们前进的同时部署一种新的光纤技术来测量冰温。冰温测量将揭示从冰下地球涌出的热量的空间模式，这反过来将极大地有助于发现包含全球气候记录的古代冰，并了解冰流可能如何提高海平面。在这个为期一年的项目中，我们的近期目标是在威斯康星大学15米高的冰柱中测试和改进我们的防冻方法，以降低未来现场测试的技术风险。技术摘要我们开发的主要目标是能够在南极冰盖内和之下广泛、空间密集地部署仪器，用于各种调查，首先是观测冰盖底部的基础温度和地热通量。密集、广泛的部署需要远低于当前冰钻和取心成本的物流成本。我们的方法是扩展冰融测头技术(本质上是轻便的，后勤上)，以允许在探头下降时从冰面逐步部署分布式温度传感(DTS)电缆，而不会大幅增加物流成本。我们的扩展是基于阻止探测器上方的熔融孔(直径是电缆直径的几倍)的重新冻结，方法是在探测器下降时在探测器上方几米处注入防冻剂--具体地说，就是在接近0摄氏度的温度下注入乙醇。在液体乙醇/水柱与冰热平衡后，DTS测量得到冰盖温度的深度剖面，由此可以推断基础温度和(冰层上)地热通量。我们已经在冷室实验室对我们的方法进行了初步试验，但仅基于这种小规模试验的现场工作可能仍然存在不必要的风险。因此，我们建议在威斯康星州麦迪逊的冰钻设计和运营(IDDO)设施中进行进一步测试。新的试验将测试我们在更高的柱中进行熔洞控制和探头回收的方法，将测试电缆和电缆张力管理方法，更接近在冰盖上工作所需的方法，并将展示现场配置的分布式温度传感。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。