Collaborative Research: GPS-based terrestrial water storage anomalies during hydrologic extremes: linking hydrologic process, solid-earth response, and monitoring networks

合作研究：极端水文期间基于 GPS 的陆地水储存异常：将水文过程、固体地球响应和监测网络联系起来

• 批准号: 1521127
• 负责人: Adrian Borsa
• 金额: $ 20.44万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1521127&HistoricalAwards=false
• 关键词: Collaborative; Research; GPS; based; terrestrial

Terrestrial water storage (TWS) is the total amount of water stored as soil moisture, groundwater, snow, in surface water bodies, and in the biosphere. Variations in TWS reflect the watershed-scale response to changes, such as drought and groundwater pumping. Observations of TWS are needed to study the water cycle and its role on the Earth, but existing tools for monitoring TWS variations are not satisfactory. Recently, global positioning system (GPS) observations of the height of the land surface have been used to quantify TWS variations. However, errors in TWS estimated from GPS data have not been quantified. This research has three components to study how GPS observations can be used to monitor TWS. First, the resolution and accuracy of TWS variations estimated from GPS land surface heights will be quantified by combining hydrologic data and a model of how the Earth deforms. Second, GPS data from several thousand stations will be used to estimate TWS variations across the continental United States for the past decade and forward in time. Third, a comparison will be made between existing TWS estimates and estimates based on GPS observations. The expected outcomes of this project will advance the start-of-the-art in TWS monitoring by evaluating the magnitude and sources of errors in GPS-based TWS data. This is a necessary step towards applying these data to a range of wide hydrologic applications, including estimates of soil water volumes and groundwater recharge, the effects of drought, and subsidence caused by changes in groundwater storage. Observations of TWS anomalies are critical for understanding how the hydrologic cycle responds to forcing such as drought. Existing tools for monitoring TWS anomalies are not optimal for many hydrologic applications. Recently, GPS observations of land surface vertical displacement have been used in novel ways to quantify the spatial and temporal variations of TWS anomalies associated with groundwater mining, seasonal snowpack, and drought. These results suggest that GPS-based records of displacement could greatly enhance monitoring of the terrestrial water cycle. However, none of the studies to date have quantified the errors in TWS anomalies estimated from GPS observations. The research plan has three components designed to assess how GPS observations can best be used to monitor TWS. First, the resolution and accuracy of TWS anomalies estimated from GPS vertical position data will be quantified by combining hydrologic loading data and models of the Earth's elastic response. Second, vertical position data from several thousand stations will be used to estimate TWS anomalies and associated errors across the continental United States, retrospectively for the past decade and forward in time. Third, a comparison will be made between existing TWS anomaly products and the product based on GPS positions. Differences will be related to hydrologic processes through analyses of in situ hydrologic observations of groundwater, soil moisture, and snow water equivalent. The expected outcomes of this project will advance the start-of-the-art in TWS monitoring by evaluating how errors in GPS-based TWS anomalies are related to interactions between hydrologic process, the solid earth response, and the monitoring network at the continental scale. This is a necessary step towards applying these data to a range of hydrologic applications.

陆地水储量（TWS）是指以土壤水分、地下水、雪、地表水体和生物圈中储存的水总量。 TWS 的变化反映了流域规模对干旱和地下水抽取等变化的响应。研究水循环及其在地球上的作用需要对 TWS 进行观测，但现有的 TWS 变化监测工具并不令人满意。最近，全球定位系统 (GPS) 对陆地表面高度的观测已被用来量化 TWS 变化。然而，根据 GPS 数据估计的 TWS 误差尚未量化。这项研究分为三个部分，研究如何使用 GPS 观测来监测 TWS。首先，将通过结合水文数据和地球变形模型来量化根据 GPS 陆地表面高度估算的 TWS 变化的分辨率和准确性。其次，来自数千个站点的 GPS 数据将用于估计过去十年及未来整个美国大陆的 TWS 变化。第三，将现有 TWS 估计值与基于 GPS 观测值的估计值进行比较。该项目的预期成果将通过评估基于 GPS 的 TWS 数据中的误差幅度和来源，推动 TWS 监测技术的进步。这是将这些数据应用于一系列广泛的水文应用的必要步骤，包括土壤水量和地下水补给的估计、干旱的影响以及地下水储存变化引起的沉降。 TWS 异常的观测对于了解水文循环如何响应干旱等强迫至关重要。现有的监测 TWS 异常的工具对于许多水文应用来说并不是最佳的。最近，地表垂直位移的 GPS 观测已以新颖的方式用于量化与地下水开采、季节性积雪和干旱相关的 TWS 异常的空间和时间变化。这些结果表明，基于 GPS 的位移记录可以极大地加强对陆地水循环的监测。然而，迄今为止，还没有一项研究对根据 GPS 观测估计的 TWS 异常的误差进行量化。该研究计划由三个部分组成，旨在评估如何最好地利用 GPS 观测来监测 TWS。首先，根据 GPS 垂直位置数据估计的 TWS 异常的分辨率和精度将通过结合水文负荷数据和地球弹性响应模型来量化。其次，来自数千个站点的垂直位置数据将用于估计美国大陆的 TWS 异常和相关误差，回顾过去十年并及时向前推进。第三，将现有的TWS异常产品与基于GPS位置的产品进行比较。通过对地下水、土壤湿度和雪水当量的现场水文观测进行分析，将差异与水文过程相关。该项目的预期成果将通过评估基于 GPS 的 TWS 异常误差如何与水文过程、固体地球响应和大陆尺度监测网络之间的相互作用相关，从而推动 TWS 监测的发展。 。这是将这些数据应用于一系列水文应用的必要步骤。