CAREER: Inversion of Localized High-Resolution Polar Gravity Fields to Estimate Mass Change

自2002年以来，GRACE系列卫星任务一直在测量地球重力场的变化。这些观测发现了目前冰盖和冰川的冰损失。冰的损失在决定21世纪海平面上升方面起着关键作用，海平面上升威胁着生活在沿海地区的数亿人。改进对今天冰消失的地点和时间的观测是改进对未来冰和海平面变化的估计的关键。这些估计对于评估相应的风险和实施缓解政策至关重要。在这里，研究人员开发并测试了新的工具，以改进卫星重力测量，特别是在极地地区。这些最新的发展提高了卫星观测的空间和时间分辨率。它们让我们更好地了解冰原和冰川是如何对不断变化的气候条件做出物理反应的，尤其是在区域尺度上，这是一个突出的科学问题。该项目还为亚利桑那大学的研究生和本科生提供地球物理和遥感方面的支持和培训。它的教育方面，与研究相结合，在课堂环境和研究实验室环境中进行。具体的努力旨在包括来自STEM中代表性不足群体的学生。目前的全球卫星重力数据产品的空间分辨率基本上受到极地地区构造方式的限制。在这里，研究小组使用空间光谱定位技术，直接从卫星高度的原位测量中构建仅限极地的时变重力场。这些极地重力场显著提高了全球产品的时空分辨率。本文利用这些数据分析了与21世纪海平面上升有关的两个问题：1)利用贝叶斯反演方法约束劳伦泰德冰盖在最后一次冰盛期的厚度和形状；2)结合格陵兰岛的GPS地表位移，研究冰质量变化如何在固体地球表面运动中表达。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The GRACE series of satellite missions have been making measurements of Earth’s changing gravity field since 2002. These observations detect present day ice loss in ice sheets and glaciers. The ice loss plays a key role in determining 21st century sea level rise, which threatens hundreds of millions of people living in coastal regions. Improving observations of where and when ice is being lost today is key for improving estimates of future ice and sea level change. These estimates are critical to assess the corresponding risks and implement mitigation policies. Here the researchers develop and test new tools to improve satellite measurements of gravity, specifically in the polar regions. These state-of-the-art developments improve the spatial and temporal resolution of satellite observations. They allow a better understanding of how ice sheets and glaciers physically respond to changing climatic conditions, notably at the regional scale, an outstanding scientific question. The project also provides support and training in geophysics and remote sensing to graduate and undergraduate students at the University of Arizona. Its educational aspects, integrated with the research, are carried out both in a classroom setting and research-lab setting. Specific efforts are geared toward including students from underrepresented groups in STEM.Current global satellite gravity data products have spatial resolution that is fundamentally limited in polar regions by how they are constructed. Here the team uses spatio-spectral localization techniques to construct polar-only time-variable gravity fields directly from the in-situ measurements at satellite altitude. These polar gravity fields significantly improve spatial and temporal resolution over global products. They are here used to analyze two problems relevant to 21st century sea level rise: 1) to constrain the thickness and shape of the Laurentide Ice Sheet at last glacial maximum using a Bayesian inversion procedure; 2) combined with GPS surface displacements in Greenland, to investigate how ice mass change is expressed in solid Earth surface motion.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.