Closing the Isotope Hydrology at Summit: Measurements of Source Regions, Precipitation and Post-deposition Processes

峰会同位素水文学闭幕：源区、降水和沉积后过程的测量

• 批准号: 1023574
• 负责人: Waleed Abdalati
• 金额: $ 180万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1023574&HistoricalAwards=false
• 关键词: Closing; Isotope; Hydrology; Summit; Measurements

The stable isotopic records from the Greenland Ice Sheet are the gold standard for understanding climate variations in the Arctic on decadal to millennial scales. While the basic tenets that underlie interpretation of isotopic information appear robust in a mean sense, meteorological and glaciological processes can confound simple interpretations. Processes of concern are variations in moisture sources, cloud processes, surface ablation, blowing snow and vapor diffusion in the firn. The project objectives are to resolve fundamental uncertainties in the controls on the isotopic composition of the ice sheet through a 3-year measurement campaign at Summit, Eureka and Reykjavik. The project will use measurements and modeling to evaluate 1) the degree to which oxygen isotopic composition and deuterium excess of snow capture variations in moisture sources versus cloud microphysical conditions, and 2) the degree to which blowing snow and vapor diffusion within the firn confound accurate interpretation of variability in the isotopic record. Continuous measurements of the isotopic composition of water vapor and daily measurements of the isotopic composition of freshly-fallen and blowing snow will be made at Summit, Eureka and Reykjavik. These will be combined with measurements of the amount, size distribution, and approximate habit of falling and blowing snow, turbulence measurements to evaluate snow lofting, surface latent heat flux (ablation and frost) and energy balance, and remote sensing of polar clouds and atmospheric structure. High-resolution firn cores will be drilled to reconcile the detailed isotopic measurements and modeling with glaciological records. The new isotope measurements will jump start an emerging international pan-Arctic cooperative network of isotope measurements, which complements Arctic observations under existing Arctic Observing Network activities. The advanced measurements at Summit enhance the site as a comprehensive observatory for monitoring and understanding Arctic change.

格陵兰冰盖的稳定同位素记录是了解北极十年至千年尺度气候变化的黄金标准。虽然解释同位素信息的基本原则在平均意义上看起来很强大，但气象和冰川过程可能会混淆简单的解释。令人关注的过程是水分来源的变化、云的过程、表面消融、吹雪和积雪中的蒸汽扩散。该项目的目标是通过在萨米特、尤里卡和雷克雅未克进行为期三年的测量活动，解决冰盖同位素组成控制方面的根本不确定性。该项目将使用测量和建模来评估1）雪的氧同位素组成和氘过量捕获水分来源与云微物理条件的变化的程度，以及2）积雪内的吹雪和蒸汽扩散混淆同位素记录中变化的准确解释的程度。将在萨米特、尤里卡和雷克雅未克对水蒸气的同位素组成进行连续测量，并每天对新降雪和吹雪的同位素组成进行测量。这些将与降雪和吹雪的数量、大小分布和大致习惯的测量、用于评估积雪、表面潜热通量（消融和霜冻）和能量平衡的湍流测量以及极地云和大气结构的遥感相结合。将钻取高分辨率的积雪芯，以使详细的同位素测量和建模与冰川学记录相一致。新的同位素测量将启动一个新兴的国际泛北极同位素测量合作网络，补充现有北极观测网络活动下的北极观测。Summit的先进测量增强了该站点作为监测和了解北极变化的综合观测站的作用。