Global Geodetic Science: Surface Mass Transport and Solid Earth Mechanics

Blewitt0125575全球定位系统(GPS)数据现在可以用来测量几毫米精度的地球表面运动。利用全球定位系统，最近的研究表明，固体地球的形状变化是由于地表水、雪和大气压力分布的季节性变化。这增加了利用GPS和地球作为“称重机”来测量地表质量随时间和地点变化的可能性。通过应用一种新的反演方法，该项目计划使用来自国际GPS服务的全球GPS数据(从1996年到2004年)，制作一部关于全球地表质量在8年内重新分配的电影，分辨率为1周。这将有助于研究人员模拟全球水循环，因为它将提供近地表水(所有形式)季节性变化的强度和地理模式的季节性变化到年代际的变化。确定全球水循环是否正在加剧是关于全球气候变化的核心科学问题。水循环加速的一个可能结果是地球水库之间的水储存的季节性循环的幅度发生变化，这个项目应该有助于量化。这个项目的第二个目标是测试地球的力学模型。目前的模型在很大程度上是基于时间尺度短得多的地震学，它们忽略了弹性的横向变化。为了检验这些模型，需要关于地表负荷的独立信息，该项目将从全球大气和水文模型、海平面数据以及遥感卫星飞行任务的数据中获得这些信息。

Blewitt0125575Global Position System (GPS) data can now be used to measure movements of Earth's surface with few-millimeter precision. Using GPS, research has recently revealed that the solid Earth changes shape due to seasonal change in the surface distribution of water, snow, and air pressure. This raises the possibility of using GPS with the Earth as a "weighing machine" to measure surface mass as it changes in time and place.By applying a new inversion method, this project plans to use worldwide GPS data from the International GPS Service (from 1996 to 2004) to produce a movie of surface mass redistribution around the globe over an 8-year period, with 1-week resolution. This will be useful to investigators modeling the global water cycle, as it will provide seasonal to decadal change in the intensity and geographic pattern of seasonal variation in near-surface water (of all forms). Determining whether the global water cycle is intensifying is a central science question concerning global climate change. One likely consequence of an accelerating water cycle is change in the amplitude of seasonal cycling of water storage between Earth's reservoirs, which this project should help to quantify.A secondary goal of this project is to test mechanical models of the Earth. Current models are largely based on seismology at much shorter time scales, and they ignore lateral variation in elasticity. To test these models requires independent information on surface loads, which this project will obtain from global atmospheric and hydrologic models, and sea level data, as well as data from remote sensing satellite missions.