Gravimetric determination of the solid-earth response to ice-mass changes in southern Patagonia

该建议旨在实现和解释南巴塔哥尼亚冰原地区（南美洲最南端）的重力观测。在申请人先前进行的调查过程中，推断在该地区有异常强烈的地壳隆起。这种变形是由固体地球对巴塔哥尼亚冰原过去和现在冰质量变化的反应引起的。目前正在进行的对过去变化的响应是由冰川均衡调整（GIA）分配的，而现在的冰块变化引起直接的弹性响应。通过提供对固体地球流变学和气候驱动的冰块演化的独特见解，对各自影响的大地测量观测对改进区域GIA模型至关重要。重复绝对重力法被证明是一种大地测量观测技术，适用于许多其他地区GIA的成功测定。然而，在巴塔哥尼亚冰原地区，还没有开始进行绝对重力测量。该项目建议在三个实地活动期间使用FG5绝对重力仪对八个站点的区域网络进行重复观测。地表重力随时间的变化将从这些观测中得出。这些将作为GIA和弹性效应的独立观测值，缩小卫星重力测量数据（GRACE和GRACE- fo任务）与GNSS大地测量观测得出的上升率之间的差距。观测到的地表重力变化将构成联合解释的基础，结合申请人和GRACE-FO卫星重力测量已经确定的变形率。这一解释将揭示伴随固体地球变形而来的质量分布。来自地球内部的质量信号和来自快速退缩的冰的质量信号的分离将导致区域粘弹性地球模型的实质性改进，从而更好地理解流变结构和当今冰质量变化模式，其空间分辨率优于卫星重力测量。了解南巴塔哥尼亚冰原地区GIA异常强度的原因，也将有助于解释在阿蒙森海海湾（南极洲西部）观察到的更快的隆起过程。该项目将受益于BKG目前在阿根廷-德国大地观测站（AGGO）的FG5-227重力仪的协同作用。

The proposal aims at the realization and interpretation of gravimetric observations in the region of the Southern Patagonian Icefield (southernmost South America). In the course of previous investigations conducted by the applicants an exceptionally intensive crustal uplift was inferred in this region. This deformation is caused by the response of the solid Earth to past and present ice-mass changes of the Patagonian icefields. Whereas the presently ongoing response to past changes is assigned by glacial-isostatic adjustment (GIA), present-day ice-mass changes cause an immediate elastic response. Geodetic observations of the respective effects are crucial to improve regional GIA models by providing unique insights into both the rheology of the solid Earth and the climatically driven ice-mass evolution. Repeated absolute gravimetry was proven to be a geodetic observation technique suitable for a successful determination of GIA in many other regions. However, in the region of the Patagonian icefields absolute gravity measurements have not been initiated yet. The project proposes to carry out a repeated observation of a regional network of eight sites using a FG5 absolute gravity meter during three field campaigns. Surface gravity changes over time will be derived from these observations. These will serve as an independent observable of GIA and elastic effects, closing a gap between satellite gravimetry data (GRACE and GRACE-FO missions) and the uplift rates derived by geodetic GNSS observations. The observed surface gravity changes will form the basis for a joint interpretation incorporating both the deformation rates already determined by the applicants and GRACE-FO satellite gravimetry. The interpretation will shed light on the mass distributions that accompany the deformation of the solid Earth. The separation between mass signals originating from the interior of the Earth and from the rapidly retreating ice will result in a substantial improvement of regional visco-elastic Earth models, in a better understanding of the rheological structure and of the present-day ice-mass change pattern with a spatial resolution superior to satellite gravimetry. Understanding the causes for the exceptional intensity of GIA in the region of the Southern Patagonian Icefield will help to also explain even faster uplift processes observed in the Amundsen Sea Embayment (West Antarctica). The project will benefit from the synergy with the current presence of BKG's FG5-227 gravity meter at the Argentine-German Geodetic Observatory (AGGO).