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Constraints on Q at long periods from Earth's rotation
Author(s) -
Dickman S. R.,
Nam Young S.
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/97gl03559
Subject(s) - geology , geodesy , mantle (geology) , earth's rotation , amplitude , speed wobble , earth model , earth structure , geophysics , seismology , physics , classical mechanics , quantum mechanics
In this work we assess constant Q and frequency‐dependent Q models of mantle anelasticity. Our assessment uses the degree 2 Love numbers we had inferred previously from a comparison of observed and predicted changes in the length of day at monthly, fortnightly, and nine‐day lunar tidal periods. The comparison accounted for variable contributions to the tidal signals by dynamic oceans, and allowed for axial core‐mantle coupling that was either complete or absent. The Love number derived from an earlier analysis of the period of the Chandler wobble is also employed. We find that the similarity of the degree 2 Love number inferred at a nine‐day period to that at seismic frequencies, combined with the significant amount of relaxation at the Chandler period, together imply that Q models operating within the seismic band cannot extend all the way to long tidal periods. Our analysis of Q also allows us to refine estimates of the Love number at fortnightly and monthly periods.