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地球表面的运动，精度为几毫米。利用GPS，最近的研究表明，由于水，雪和气压表面分布的季节性变化，固体地球会改变形状。这就有可能利用全球定位系统，把地球作为“称重机”，随着时间和地点的变化来测量表面质量，该项目计划采用一种新的反演方法，利用国际全球定位系统服务处提供的全球全球定位系统数据（1996年至2004年）制作一部8年期间地球仪周围表面质量重新分布的影片，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到十年变化。确定全球水循环是否正在加强是有关全球气候变化的核心科学问题。水循环加速的一个可能后果是地球水库之间水储存的季节性循环幅度的变化，该项目应有助于量化。该项目的第二个目标是测试地球的力学模型。目前的模型主要是基于地震学在更短的时间尺度，他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，本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.