Improved ice-mass balance and GIA-induced sea-level change by assimilation of GRACE and SLI data to 3D viscoelastic earth model and joint gravity field inversion

南极冰盖(AIS)和格陵兰冰盖(GIS)是地球气候系统的重要组成部分，对当今海平面变化有重大贡献。对它们过去和现在状态的了解将增强我们对气候系统变化的理解，并改进对全球气温和海平面变化近期演变的模拟。AIS和地理信息系统的质量随时间的变化是反映冰盖当前动态的重要指标。重力恢复和气候实验(GRACE)卫星任务监测重力场的时间变化，为地球系统中的质量变化提供了新的约束。然而，特别是在南极洲，由于冰川均衡调整(GIA)污染了GRACE估计的冰块平衡，冰块质量的变化叠加了地幔中的质量重新分配。反过来，GRACE数据代表了GIA引起的质量变化和表面变形的一个重要的新约束，这代表了当今相对海平面变化的重要信号。该项目旨在通过使用三维粘弹性地球模型对南极洲和北美的GRACE数据进行联合反演，同时约束现今冰块变化和GIA。为了减少反演中的模糊性，ICESat数据和过去10,000年的海平面指标将被伴随技术同化。AGIA的结果将改进对冰盖引起的海平面变化和海平面升降对现今相对海平面变化的贡献的估计。

The Antarctic ice sheet (AIS) and the Greenland ice sheet (GIS) are important components of the Earth’s climate system, contributing significantly to present-day sea-level change. The knowledge of their past and present state will enhance our understanding of changes in the climate system, and improve the modelling of the near-future evolution of global temperature and sea-level change. The temporal variation of mass of the AIS and GIS are important indicators of the ice sheets’ current dynamical state. The Gravity Recovery and Climate Experiment (GRACE) satellite mission monitoring temporal variations of the gravity field provides new constraints on mass changes in the Earth’s system. However, particularly in Antarctica, ice-mass changes are superimposed by the mass redistribution in the Earth’s mantle due to glacial-isostatic adjustment (GIA) contaminating ice-mass balance estimates from GRACE. In turn, GRACE data represents an important new constraint GIA-induced mass changes and surface deformation, which represents an important signal of present-day relative sea-level change. This project aims at simultaneously constraining present-day ice-mass changes and GIA by a joint inversion of the GRACE data for Antarctica and the North America using a three-dimensional viscoelastic earth model. To reduce ambiguities in the inversion, ICESat data and sea-level indicators for the past 10,000 years will be assimilated by the adjoint technique. The results of AGIA will provide an improved estimate of the GIA-induced and eustatic contribution caused by the ice sheets to present-day relative sea-level change.