EAPSI: The Effect of Seasonal Hydrological Loading on Vertical GPS Time Series

连续的GPS时间序列最近使研究各种地面变形源成为可能。一个非构造变形源，特别是重要的垂直GPS时间序列，是弹性载荷的季节性变化。例如，当蓄水池每年在空和满之间循环时，可能会发生这种情况。如果水负荷的GPS时间序列的贡献可以建模和理解，它是可能的，使及时，准确，当地有用的估计地表水存储简单地从GPS测量。为此，本研究旨在确定缅甸连续GPS测量的地表水负荷的组成部分。已知该数据集中的垂直GPS信号包含世界上最大的一些年度振荡，可能是由于亚洲季风。然而，地表水储存量的变化在多大程度上可以解释GPS振荡仍然是未知的。这项工作将由新加坡地球观测站全球定位系统大地测量学的主要研究人员Emma Hill教授完成。这项研究还将受益于与希尔博士研究小组中许多研究人员的合作，这些研究人员正在对缅甸的大地测量数据进行大规模研究。该项目将通过一个载荷模型将GPS时间序列分解为弹性载荷和其他来源的分量。GRACE卫星使命的重力测量将用于限制地表水负荷。然后将使用参考地球结构对每个GPS站的弹性变形进行建模。据推测，在垂直GPS时间序列的季节性变化，可以达到5厘米/年的振幅，是由于水文负荷。该项目将产生一个特定的模型的季节性负荷对变形场的影响。全球定位系统和GRACE时间序列之间的相互关系还应提供缅甸每个连续的全球定位系统站当地具体的水储存水平估计数。该奖项是在东亚和太平洋夏季研究所计划下设立的，旨在支持美国研究生的夏季研究，由NSF和新加坡国家研究基金会共同资助。

Continuous GPS time series have recently enabled the study of a variety of ground deformation sources. One non-tectonic deformation source, particularly important for vertical GPS time series, is seasonal changes in elastic loading. For example, this can occur when water reservoirs annually cycle between empty and full. If the contributions of water loading to the GPS time series can be modeled and understood, it is possible to make timely, accurate, and locally useful estimates of surface water storage simply from GPS measurements. To that end, this study aims to identify the components of surface water loads in the continuous GPS measurements from Myanmar. The vertical GPS signals in this dataset are known to contain some of the largest annual oscillations in the world, likely due to the Asian Monsoon. However, the degree to which changes in surface water storage can explain the GPS oscillations remains unknown. This work will be completed with Professor Emma Hill, a leading researcher in GPS geodesy at the Earth Observatory of Singapore. This research will also benefit from collaboration with the many researchers in Dr. Hill's research group who are working on a large-scale study of geodetic data from Myanmar. This project will decompose the GPS time series into components from elastic loading and other sources through a loading model. Gravity measurements from the GRACE satellite mission will be used to constrain surface water loads. The elastic deformation will then be modeled for each GPS station using a reference earth structure. It is hypothesized that much of the seasonal variation in the vertical GPS time series, which can reach 5 cm/year in amplitude, is due to hydrologic loading. This project will produce a specific model of the seasonal loading effects on the deformation field. The correlations between the GPS and GRACE time series should also provide locally specific estimates of water storage levels at each continuous GPS station in Myanmar. This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the National Research Foundation of Singapore.