Global Geodetic Science: Surface Mass Transport and Solid Earth Mechanics

Board Of Regents, Nshe, Obo University Of Nevada, Reno, Reno NV

Investigators

Abstract

Blewitt 0125575 Global 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.