Improved constraints on global-scale hydrological change by determining secular geocenter motion and low degrees of the surface mass load.

气候变化引起的冰融化和海平面上升又引起了地表水质量的大规模再分布。这种大规模的水团运动改变了地球的重力场，使地球表面变形，这样地球基本上就承受了水的重量。因此，对地球重力场和地表变形的测量可以对大规模的水团运动施加限制。传统的水文实验没有全球覆盖范围来限制这种大规模的水运动，而卫星测量在这方面要好得多。尽管如此，在最大的空间尺度上进行测量被证明是有问题的，例如；这种质量运动的半球间组成部分的长期变化尚未得到测量，并且在知识方面存在相当大的差距。没有这些知识，要对海平面上升进行精确的测量将是困难的。在这里，我们建议通过开发一个综合观测模型，利用GRACE和SLR的重力测量以及GPS的地球形状测量来推断过去20年的大尺度水团运动。此外，我们的结果将改善整个地球科学中使用的陆地参考框架的实现，特别是用于海平面上升的高度计和潮汐计估计。

Ice melting and sea level rise caused by climatic change in turn cause large-scale redistribution of surface water mass. Such large-scale water mass movements alter the Earth's gravity field and deform the Earth's surface, such that the Earth essentially weighs the water load. Measurements of the Earth's gravity field and surface deformation can therefore place constraints on large scale movements of water mass. Conventional hydrological experiments do not have the global coverage to constrain such large-scale water movements, whereas satellite measurements are far better placed in this regard. Despite this, measurement at the largest spatial scales has proved problematic, for example; long term changes in the inter-hemispheric component of this mass motion are as yet unmeasured and present a considerable gap in knowledge. Without this knowledge making accurate measurements of sea level rise will prove difficult. Here we propose to infer large scale water mass movements over the past two decades by developing an integrated observation model using gravity measurements from GRACE and SLR, and measurements of the Earth's shape from GPS. In addition, our results will improve the realisation of the Terrestrial Reference Frame used throughout the Earth Sciences and in particular for altimetric and tide gauge estimates of sea level rise.