River Plumes as Indicators for Greenland Ice Sheet Melt

河流羽流作为格陵兰冰盖融化的指标

• 批准号: 0909349
• 负责人: Irina Overeem
• 金额: $ 35.85万
• 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: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0909349&HistoricalAwards=false
• 关键词: River; Plumes; Indicators; Greenland; Ice

This project will study Greenlandic Rivers as integrated signals of a rapidly changing Arctic hydrological cycle. Observed increased rates of melt on the Greenland Ice Sheet (GrIS) are expected to have a profound impact on the runoff of numerous rivers draining the ice sheet margin. However, there are few observational records of water discharge of Greenlandic Rivers, or any other observations to constrain runoff to systematically assess the freshwater drained to the ocean. The researchers will use an innovative methodology to infer river discharges around Greenland from the characteristics of river plumes draining into the fjords. River plumes are prominently visible on remote-sensing imagery, and their dimensions and reflectance characteristics can be mapped on a daily-weekly basis over the length of the MODIS satellite record, which will amount to a detailed reconstruction of 10+ years. Plume characteristics are related to sediment concentration patterns and sediment removal rates by empirical transfer functions, which will be validated against 4 years of field data. River plumes are typically controlled by incoming river discharge and sediment load. Inverted process-based numerical model of river plumes in fjords use the mapped plume parameters to then quantify the associated river runoff.This work will provide a rarely obtainable high spatial resolution record especially in Southern and Western Greenland, where numerous rivers drain into fjords. Runoff data will be related to observed melting rates at automated weather stations of the Greenland Climate Network as well as to longer-term temperature and precipitation trends of existing meteorological stations in the fjords to enhance process understanding of runoff dynamics. Lag time between onset and duration of melt on the ice sheet and downstream river discharge patterns contributes to understanding of the presently hotly debated pathways of GrIS melt water to the global ocean. A comprehensive dataset of Greenland river discharge will be useful in better estimating the portioning of observed ice mass lost on the GrIS, between melt water runoff and calving glacier ice discharges. The dataset will be used to evaluate and improve melt and runoff routines for the Community Land Model/Greenland ice sheet model component of the Community Climate System Model by comparing MODIS reconstructions with CCSM output. The reconstructed runoff data has the potential to expose deficiencies in modeled Greenland runoff and will therefore serve as a validation dataset to direct future ice sheet/land model improvements.

该项目将研究格陵兰河作为快速变化的北极水文循环的综合信号。观测到的格陵兰冰原（GrIS）融化速度的增加预计将对排干冰原边缘的众多河流的径流产生深远影响。然而，很少有格陵兰河排水的观测记录，也没有任何其他观测来限制径流，以系统地评估流入海洋的淡水。研究人员将使用一种创新的方法，根据流入峡湾的河流羽流的特征来推断格陵兰岛周围的河流排放量。河流羽流在遥感影像上非常明显，它们的尺寸和反射率特征可以在MODIS卫星记录的长度上每天每周绘制，这将相当于10多年的详细重建。羽流特征通过经验传递函数与沉积物浓度模式和沉积物去除速率相关，并将根据4年的现场数据进行验证。河流羽流通常由来水流量和泥沙负荷控制。基于倒过程的峡湾河流羽流数值模型使用映射的羽流参数来量化相关的河流径流。这项工作将提供难得的高空间分辨率记录，特别是在格陵兰岛的南部和西部，那里有许多河流流入峡湾。径流数据将与格陵兰气候网自动气象站观测到的融化速度以及峡湾现有气象站的长期温度和降水趋势有关，以加强对径流动力学过程的了解。冰盖融化开始和持续时间之间的滞后时间以及下游河流的排放模式有助于理解目前热议的GrIS融水流向全球海洋的途径。格陵兰河流量的综合数据集将有助于更好地估计GrIS上观测到的冰质量损失的比例，即融水径流和冰川崩解冰流量之间的比例。该数据集将通过比较MODIS重建和CCSM输出，用于评估和改进社区气候系统模式中社区土地模式/格陵兰冰盖模式组件的融化和径流过程。重建的径流数据有可能暴露出模拟格陵兰径流的不足，因此将作为一个验证数据集，指导未来冰盖/陆地模型的改进。