Assessing the current Evolution of the Greenland Ice Sheet

该项目的目标是结合观测数据和冰川学模型，帮助更准确地评估格陵兰冰盖及其主要流域的当前演变情况。该项目的模拟部分包括一个全面的三维热机械冰盖模型、一个地表融化和径流模型以及一个计算平衡速度的模型，此外还有一个区域大气气候模型和一个粘弹性自引力固体地球模型。模拟将主要产生长期的冰盖和基岩演化以及过去几十年的地表物质平衡。观测数据来自GRACE的随时间变化的大地水准面，ICESat和ERS-1/ERS-2/ENVISAT的测高数据，ASTER的光学数据，ERS-1/2，ENVISAT和TerraSAR的SAR数据，以及地基GPS数据。这些数据将提供测量平台期间表面高程变化、重力变化、表面速度和表面累积速率的快照。该项目依赖于观测分析和建模之间的强烈交互作用，以将冰块贡献与冰川后均衡反弹的贡献分开，将冰盖动态变化与年际表面质量平衡变化分开，并将长期冰动态变化与短期流量波动分开。其结果将是改进对格陵兰冰盖目前对全球海平面变化的贡献的估计，并更好地了解对当前冰块变化及其相关不确定性的各种贡献。

The objective of the project is to contribute to a more accurate assessment of the current evolution of the Greenland ice sheet and its major drainage basins from a combination of observational data and glaciological modeling. The modeling component of the project consists of a comprehensive three-dimensional thermomechanical ice-sheet model, a surface melt and runoff model, and a model to calculate balance velocities, with further input from a regional atmospheric climate model and a visco-elastic self-gravitating solid Earth model. The modeling will primarily yield the long-term ice sheet and bedrock evolution as well as the surface mass balance over the last few decades.The observational data come from the time-dependent geoid from GRACE, altimetry from ICESat and ERS-1/ERS-2/ENVISAT, optical data from ASTER, SAR data from ERS-1/2, ENVISAT and TerraSAR, and ground-based GPS data. These data will provide snapshots of surface elevation changes, gravity changes, surface velocity, and surface accumulation rate over the duration of the measurement platforms.The project relies on a strong interaction between observational analyses and modeling to separate the ice mass contribution from the contribution of postglacial isostatic rebound, to separate ice-sheet dynamic changes from interannual surface mass balance changes, and to separate long-term ice-dynamic changes from short-term flow fluctuations. The result will be an improved estimate of the present-day contribution of the Greenland ice sheet to global sea-level change and a better understanding of the various contributions to current ice mass changes and their associated uncertainties.