HR: 1330h
AN: G22A-0305    [PDF]
TI: How important is the lateral variation of mantle density to earth rotation in tidal frequencies
AU: * Liu, L
EM: lanbo.liu@uconn.edu
AF: Department of Geology and Geophysics, University of Connecticut, 354 Mansfield Road, U-2045, Storrs, CT 06269-2045 United States
AU: Kuang, W
EM: Kuang@santafe.gsfc.nasa.gov
AF: Goddard Space Flight Center, NASA, Space Geodesy Branch, Code 926, Greenbelt, MD 20731 United States
AU: Chao, B F
EM: chao@santafe.gsfc.nasa.gov
AF: Goddard Space Flight Center, NASA, Space Geodesy Branch, Code 926, Greenbelt, MD 20731 United States
AB: Advances in space geodesy in the last couple of decades have made two types of precise geophysical data available: (i) tidal signals in the Earth's rotational speed variations and polar motion; and (2) the contribution of ocean tides to the above signals as predicted by satellite altimetry derived tide models. The difference of the two, at all tidal periods (long-periods, diurnals, and semidiurnals), contains contributions of the lateral density heterogeneity of the mantle. We developed an algorithm and conduct the computation using 3-demensional mantle heterogeneity models derived by seismological and gravity means (e.g., the SPRD6 model, Isshii and Tromp, 1999). We discuss the importance of the mantle heterogeneity by comparing with the earth rotation observations conducted by NASA using VLBI networks, and the ocean tides model derived from Topex/Poseidon. In general, the effect from ocean tides accounts for more than 90% of the observed polar motion signals in the tidal frequencies, while the effect from the solid mantle only accounts for less than 10%. Accounting for the effect from the density heterogeneity in the mantle reduced the said discrepancy in the observed tidal signals. Conversely, the latter signals therefore provide global constraints to 3D mantle density models for a better understanding of the internal dynamics of the solid Earth.
DE: 1239 Rotational variations
DE: 1249 Tides--Earth
DE: 8160 Rheology--general
SC: Geodesy [G]
MN: 2003 Fall Meeting