HR: 11:20h
AN: G51C-05 INVITED     [PDF]
TI: Mass Loads, Surface Deformation, and the Earth's Rotation
AU: * Gross, R S
EM: Richard.Gross@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099 United States
AU: Blewitt, G
EM: gblewitt@unr.edu
AF: Nevada Bureau of Mines and Geology and Seismological Laboratory, University of Nevada, Reno, NV 89557-0088 United States
AU: Blewitt, G
EM: gblewitt@unr.edu
AF: School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle, NE1 7RU United Kingdom
AU: Clarke, P J
EM: Peter.Clarke@newcastle.ac.uk
AF: School of Civil Engineering and Geosciences, University of Newcastle upon Tyne, Newcastle, NE1 7RU United Kingdom
AU: Clarke, P J
EM: Peter.Clarke@newcastle.ac.uk
AF: Colorado Center for Astrodynamics Research, University of Colorado, Boulder, CO 80309-0431 United States
AU: Lavallee, D A
EM: lavallee@unr.edu
AF: Nevada Bureau of Mines and Geology and Seismological Laboratory, University of Nevada, Reno, NV 89557-0088 United States
AB: A fluid, mobile atmosphere and oceans surrounds the solid Earth and upon its land surface lies a continually changing global distribution of ice, snow, and ground water. The changing distribution of mass associated with the motion of these surficial fluids changes the load on the solid Earth, thereby causing its shape to change. It has recently been demonstrated that large-scale changes in the shape of the Earth's surface can be measured using the global network of GPS receivers. Any dynamic Earth process that rearranges the Earth's mass will, in general, change the Earth's inertia tensor, and hence change the Earth's rotation. Thus, many (if not all) of the dynamic Earth processes causing the Earth's shape to change will also cause variations in the Earth's rotation. Observations of changes of both the Earth's shape and rotation arising from the same underlying dynamic process should, of course, be consistent with each other. Here, observations of changes in the Earth's shape are used to infer changes in the mass load that are causing the Earth's shape to change. The second-degree harmonics of this inferred mass load are then used to compute the change in the Earth's inertia tensor and hence the change in the Earth's rotation. This predicted change in the Earth's rotation is then compared to observations of the Earth's rotation. Prior to this comparison, motion effects due to winds and currents on the Earth's rotation are first removed from the observations using the NCEP/NCAR reanalysis atmospheric model and a data-assimilating version of the ECCO ocean model, respectively. It is shown that there is a good agreement between the observed changes in the Earth's rotation and those predicted by the inferred mass load, particularly at seasonal frequencies.
DE: 1223 Ocean/Earth/atmosphere interactions (3339)
DE: 1239 Rotational variations
SC: Geodesy [G]
MN: 2003 Fall Meeting