Collaborative Research: A field validated model for melt water infiltration and runoff from the Greenland Icesheet

卫星观测表明，格陵兰冰盖（GIS）的表面融化范围逐年增加。在渗透相（一个环绕冰盖的中间高度的宽带），雪融化的面积和持续时间都在增加。 然而，由于对格陵兰渗滤相的现场观测极为有限，因此融水的命运尚不清楚。这些变化的最终水文结果是一个显着的变化，从GIS的融水生产和径流，然而，雪过程和径流之间的耦合记录不足。特别是，径流限制，海拔以上的季节性熔体渗透，refreezes，并没有逃脱，位于较高的部分的渗滤相，但其精确的位置一般是未知的，和响应的径流限制变暖知之甚少。目前的GIS对海平面上升的贡献的模型使用的模型，建立了粗略的边界上的“径流限制”的长期增加融化的反应。这项研究将量化融水径流过程和近地表积雪致密化的GIS的渗滤相的变化，并将产生一个新的和高度改进的径流模型，是锚定在实验观察。实验将在Crawford Point地区的一条横断面（从海拔约2025 m延伸至1500 m）的沿着地点进行。具体目标有两个方面：1）主要研究人员将确定千米尺度的融水流速和路径，作为径流模型的校准; 2）。他们将调查近地表致密化速率的变化和跨越25年的记录过程。这项工作将增加我们的理解和预测能力的一部分融水的冰盖上运行，记录发生在冰盖上的重要物理过程的变化，并提供罕见的地面观测比较基于卫星的测量表面融化。这些都有重要的影响，解释冰盖的表面海拔，质量平衡和流动动力学，并最终，全球海平面。更广泛的影响：主要研究人员是积极的教师从事本科和研究生教学，研究生指导。他们将共同教授超过90个学分的本科和研究生课程。这项研究和相关的科学问题将为许多课程增加教学效益。该项目将导致至少四个研究生学位。他们定期与k-12，公众和石油和天然气行业进行外展活动。

ABSTRACTHarperOPP-0612506PffefferOPP-0612351HumphreyOPP-0612374Satellite observations suggest substantial year-to-year increases in surface melt extent of the Greenland Ice Sheet (GIS). Both the area and duration of snow melting in the percolation facies, a wide band of intermediate elevation that circumscribes the ice sheet, are increasing. The fate of the melt water, however, is unclear as in-situ observations in Greenland's percolation facies have been extremely limited. The ultimate hydrologic result of these changes is a significant change in meltwater production and runoff from GIS, however, the coupling between snow processes and runoff are poorly documented. In particular, the runoff limit, the altitude above which seasonal melt infiltrates, refreezes, and does not escape, lies within the higher part of the percolation facies, but its precise location is generally unknown, and the response of the runoff limit to warming is poorly understood. Current models for present and future contributions of GIS to sea level rise use a model which established rough bounds on the response of the "runoff limit" to secular increases in melt. This research will quantify melt water runoff processes and changes in near-surface firn densification in the percolation facies of GIS and will produce a new and highly improved model for runoff that is anchored in experimental observations. Experiments will be conducted at sites along a transect in the region of Crawford Point, extending from about 2025 m to 1500 m elevation. Specific objectives are twofold: 1) the Principal Investigators will determine km-scale melt water flow velocities and pathways which will serve as calibration for their runoff model; and 2). they will investigate change in near-surface densification rates and processes in records that span over 25 years. This work will increase our understanding and prediction capabilities of the fraction of meltwater which runs off the ice sheet, document change in important physical processes occurring on the ice sheet, and provide rare ground observations for comparison to satellite based measurements of surface melt. Each of these has important implications for interpretation of the ice sheet's surface elevation, mass balance, and flow dynamics and ultimately, global eustatic sea level.Broader Impacts: The Principal Investigators are active teaching faculty engaged in undergraduate and graduate teaching, and graduate student mentoring. They will collectively teach over 90 credit hours of undergraduate and graduate courses. This research and related scientific issues will add pedagogical benefit to numerous courses. This project will lead to at least four graduate degrees. They regularly conduct outreach activities with k-12, the general public, and the oil and gas industry.