2007 Fall Meeting          
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Cite abstracts as Author(s) (2007), Title, Eos Trans. AGU,
(52), Fall Meet. Suppl., Abstract xxxxx-xx
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HR: 11:35h
AN: G32A-06
TI: Towards a Future Predictive Non-Linear Terrestrial Reference Frame for Improved Geodetic Monitoring of the Global Hydrological Cycle
AU: * Plag, H
EM: hpplag@unr.edu
AF: Nevada Bureau of Mines and Geology and Seismological Laboratory, University of Nevada, Reno, Mail Stop 178, Reno, NV 89557, United States
AB: Geodetic techniques have a great potential to monitor mass transport in the Earth system. In particular, the combination of space-geodetic techniques present in the Global Geodetic Observing System (GGOS) constitutes a unique system for monitoring the mass transport in the hydrological cycle on regional to global scale. However, in order to separate the signals induced by water transport from other geophysical signals and instrumental effects, consistency of the models used in the space-geodetic analyses is crucial. Moreover, the conceptual approach to the reference frame has to ensure preservation of the water-related signals (i.e., no aliasing into other quantities, no biasing, and no reduction due to implicit filtering). The current concept for the International Terrestrial Reference Frame (ITRF) is that of a secular (linear) polyhedron augmented by a small set of conventional models for high-frequency surface deformation largely decoupled from variations in gravity and rotation. This concept is not appropriate at the accuracy level of 10-9 or better that is required to fully develop GGOS into a water-cycle monitoring system. Moreover, the traditional interpretation of geodetic observations aims at the separation of effects. However, in the hydrological cycle all mass movements are interrelated. Consequently, the geodetic observations capture signals from the atmosphere, terrestrial hydrosphere, cryosphere and ocean, which interact with each other through gravity forces and surface displacements at a level detectable by present-day geodetic techniques. Therefore, an integrated approach to reference frame modeling is required in geodesy, similar to, for example, the modeling of ocean circulation, climate, and weather. In these cases, assimilation of data into integrated predictive models has proved to be a successful strategy. In order to resolve the current inconsistencies of the models and the conceptual inadequacy of the ITRF for high- accuracy monitoring of the global and regional hydrological cycle, a Dynamic Earth Reference Model (DREM) is proposed which consistently models the changes in Earth's shape, gravity field and rotation induced, in particular, through mass transport in the hydrological cycle. This DREM will have to account for geophysical processes with a predefined target accuracy derived from the monitoring goals, and the conservation of water mass in the Earth system. It will require ongoing and consistent assimilation of geodetic observations of surface displacements, gravity field changes and Earth's rotation perturbations. The DREM will provide a basis for an extended reference frame concept with high temporal and spatial resolution, which accounts for intraseasonal to interannual variations in the geodetic parameters caused by mass transport. We will present the principle components of the DREM, discuss the main challenges in implementation, indicate the necessary extensions of the theory describing deformations of the solid Earth due to surface and body forces, and summarize the current status.
DE: 1218 Mass balance (0762, 1223, 1631, 1836, 1843, 3010, 3322, 4532)
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
DE: 1229 Reference systems
SC: Geodesy [G]
MN: 2007 Fall Meeting

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