HR: 11:05h
AN: G32A-04    [Abstracts]
TI: Non-periodic near-surface mass variations and their impact on Earth's rotation
AU: * Hengst, R
EM: rico@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg A17, Section 1.3, Potsdam, 14473, Germany
AB: The variability in the Earth's rotation rate and the orientation of its axes can be observed by modern geodetic space techniques. % To identify the underlying geophysical excitation potential it is common practise to describe the dynamical mechanisms in the Earth's subsystems with independent methods (in-situ observations or numerical models). % In this investigation we analyse the contribution of near-surface mass redistributions on continents using three hydrological models in terms of variations of the effective angular momentum functions χ. % A focus is laid in this study on episodic and quasi-periodic signals in the hydrological χ-functions. % Wavelet analyses reveal similar and significant non-periodic signals in all investigated hydrological models. % These results are verified by comparisons with geodetic observations after accounting for tidal, atmospheric and oceanic effects. % Typical climate relevant variability patterns, such as the Indian monsoon, the El Niño Southern Oscillation (ENSO), the Quasibiennial Oscillation (QBO) and the Tropospheric Biennial Oscillation (TBO), are identified as possible causes of episodic and quasi-periodic variations in continental water storage and, consequently, in those of the χ-functions. % The application of wavelet analyses to individual continents points out that such non-periodic variations in the total hydrological χ-functions are mainly caused by water storage changes in South America, Australia and Asia.
DE: 1223 Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions (0762, 1218, 3319, 4550)
DE: 1239 Earth rotation variations
DE: 1836 Hydrological cycles and budgets (1218, 1655)
SC: Geodesy [G]
MN: 2007 Fall Meeting