River Plumes as Indicators for Greenland Ice Sheet Melt

该项目将研究格陵兰河流作为北极水文循环迅速变化的综合信号。格陵兰冰盖（GrIS）融化速度的增加预计将对冰盖边缘众多河流的径流产生深远影响。然而，很少有观测记录的水排放的格陵兰河流，或任何其他观测约束径流系统地评估淡水排入海洋。研究人员将使用一种创新的方法，从流入峡湾的河流羽流的特征中推断格陵兰岛周围的河流流量。河流羽流在遥感图像上清晰可见，其尺寸和反射特性可以在中分辨率成像分光仪卫星记录的整个期间内按日/周绘制，这相当于10多年的详细重建。烟羽特征与泥沙浓度模式和泥沙去除率的经验传递函数，这将对4年的现场数据进行验证。河流羽流通常由流入的河流流量和泥沙负荷控制。峡湾河流羽流的反演过程为基础的数值模型使用映射羽流参数，然后量化相关的河流径流。这项工作将提供一个难得的高空间分辨率记录，特别是在格陵兰岛南部和西部，那里有许多河流流入峡湾。径流数据将与格陵兰气候网络自动气象站观测到的融化率以及峡湾现有气象站的较长期温度和降水趋势相联系，以加强对径流动态过程的了解。冰盖融化和下游河流流量模式的开始和持续时间之间的滞后时间有助于理解目前激烈争论的GrIS融水到全球海洋的途径。格陵兰河流量的综合数据集将有助于更好地估计观测到的冰量损失的GrIS之间的融水径流和崩解冰川冰排放的分配。该数据集将被用来评估和改善社区土地模型/格陵兰冰盖模型的社区气候系统模型的组成部分，通过比较中分辨率成像光谱仪重建CCSM输出的融化和径流例程。重建的径流数据有可能暴露模拟格陵兰径流的不足之处，因此将作为验证数据集，以指导未来的冰盖/陆地模型的改进。

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.