Open AccessThe Earth's C 21 and S 21 gravity coefficients and the rotation of the core
Author(s) -
Wahr John M.
Publication year - 1987
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1987.tb01379.x
Subject(s) - earth's rotation , geophysics , mantle (geology) , rotation (mathematics) , geodesy , physics , inner core , polar motion , geology , polar , core–mantle boundary , geometry , astronomy , mathematics
Summary Observational results for the Earth's C 21 and S 21 gravity coefficients can be used to constrain the mean equatorial rotation of the core with respect to the mantle. Current satellite gravity solutions suggest the equatorial rotation rate is no larger than 1 X 10 ‐7 times the Earth's diurnal spin rate, a limit more than one order of magnitude smaller than the polar rotation rate inferred from the westward drift of the Earth's magnetic field. The next generation gravity solutions should improve this constraint by more than one order of magnitude. Implications for the fluid pressure at the core–mantle boundary and for the shape of that boundary are discussed.