The Gravity Field in Antarctica: Geodetic Modelling and Geophysical Inversion (AntGrav)

重力场反映了地球的质量分布。因此，它可以研究其内部结构和构造演化。在这方面，重要的是准确了解具体边界表面的几何形状，例如地形和壳幔边界(莫霍洛维克不连续)。在南极洲，被厚达4000米的冰盖覆盖的冰下地形特别令人感兴趣。此外，大地水准面作为一个独特的等位面，在海洋学(用于动态海洋地形)和大地测量学(用于高度系统和全球统一的高度基准面)中充当参考面。现在，将第一次有可能以均匀和一致的方式在大陆尺度上研究南极的重力场。最近，一个国际财团出版了一份新的南极陆基重力数据汇编，其中一位申请者是主要作者(Scheinert等人，2016年)，这为这一点提供了便利。因此，我们的目标是联合两个申请者的专业知识，一方面是基于GRACE和GOCE等现代卫星重力任务的全球重力场建模，另一方面是基于地面和近地表重力测量的南极洲区域重力场改善。因此，我们提议的主要目标是确定一个组合的、一致的、高分辨率的南极洲重力场模型。这将基于对南极陆地重力数据及其与卫星数据的结合进行彻底的验证和同质化。我们将开发所有重力数据的最佳组合的创新方法，调查区域和针对区域量身定做的全球方法，同时考虑精度和光谱分辨率等不同属性。利用这个改进的全大陆重力场模型，进一步的目标是研究包括密度和几何(冰下地形、莫霍面深度)在内的岩石圈反演。为此，我们将利用额外的数据，如来自无线电回波探测(RES)和接地线位置的冰厚度测量。重力数据的反演将使用复杂的方法，并以不同的方式约束这些附加数据。因此，我们的目标是帮助克服我们对南极洲冰下地形和岩石圈结构知识的不足。结合重力场模型和约束重力反演的方法还需要进一步发展和适应南极的具体情况。重力场模型和岩石圈模型将得到现实的不确定性估计的补充。最后，将评估这些模型对几个地球科学学科的影响，并将在科学路线图中概述它们的可用性。

The gravity field reflects the mass distribution of the Earth. Thus, it allows studying its inner structure and tectonic evolution. In this respect, it is important to gain precise knowledge of the geometry of specific boundary surfaces respectively surfaces of distinct density contrast such as the topography and the crust-mantle boundary (Mohorovicic discontinuity). In Antarctica, the subglacial topography that is covered by an ice sheet of up to 4,000 m thickness is of special interest. Additionally, the geoid as a distinct equipotential surface serves as a reference surface, for instance, in oceanography (for dynamic ocean topography) and in geodesy (for height systems and a globally unified height datum).For the very first time it will now be possible to study the gravity field in Antarctica on a continental scale and in a homogeneous and consistent way. This is facilitated by the recent availability of a new Antarctic-wide compilation of ground-based gravity data published by an international consortium with one of the applicants being lead author (Scheinert et al., 2016). Thus, we aim to unite the expertise of both applicants in global gravity field modelling based on modern satellite gravity missions such as GRACE and GOCE on the one hand, and in regional gravity field improvement in Antarctica based on terrestrial and near-surface gravity measurements on the other hand. Hence, the main objective of our proposal is to determine a combined, consistent, high-resolution gravity field model of Antarctica. This will be based on a thorough validation and homogenization of the Antarctic terrestrial gravity data and their combination with satellite data. We will develop innovative methods for an optimal combination of all gravity data investigating regional and regionally tailored global approaches taking different properties like accuracy and spectral resolution into account. Using this improved continental-wide gravity field model a further objective is to investigate the lithospheric inversion including density and geometry (subglacial topography, Moho depths). For this, we will make use of additional data like ice thickness measurements from radio echo sounding (RES) and grounding line locations. The inversion of the gravity data will utilize sophisticated methods with different ways of constraining by those additional data. Thus, we aim to contribute to overcoming the deficiencies of our knowledge of subglacial topography and lithospheric structure in Antarctica. Both the methods for combined gravity field modelling and gravity inversion with constraints have to be further developed and adapted to the specific situation in Antarctica.The gravity field model as well as the lithospheric model will be complemented by realistic uncertainty estimates. Finally, the impact of these models on several geoscientific disciplines will be assessed, and their usability will be outlined in a scientific roadmap.