Data of Core Angular Momentum Changes

The zonal toroidal t_1^0 and t_3^0 components of a fully time dependent geostrophic  flow constructed under the frozen flux hypothesis are used to estimate the core angular momentum (CAM) using the hypothesis of Jault Gire and Le Mouel  (1988). The CAM is then transformed into an equivalent change in the length of the day as  seen on the solid earth by conservation of angular momentum. The predictions only give relative changes in the lod, therefore an arbitrary offset  should be chosen in order that the predictions agree reasonably well  with the lod series from astronomical observations. A value of 3.25 milliseconds has been added to the predictions to give the values presented here.

Description of the data used for model computation :
The magnetic field and its rate of change at the core-mantle interface was computed at 2.5 year intervals from field model ufm1 of Bloxham & Jackson (1992)

References to be mentioned when data are used :
R. Hide, D. H. Boggs and J. O. Dickey, "Angular Momentum fluctuations within the Earth's liquid core and torsional oscillations of the core-mantle system", Geophys. J. Int. 143, 777-786, 2000.

Related references :

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