title:  New and refined constraints on three-dimensional
	 Earth structure from normal modes below 3 mHz

authors:  Joseph S. Resovsky and Michael H. Ritzwoller

We present the results of generalized spectral fitting
(GSF) regressions which estimate normal mode structure
coefficients for the observable spheroidal and toroidal
free oscillation multiplets below 3 mHz.  The size,
accuracy, and precision of our new catalogue of modal
constraints make it a powerful new tool for assessing
and refining three-dimensional Earth models.  The
estimates include more than 3100 coefficients for 90
multiplets and 25 pairs of coupled multiplets, including
several deep mantle overtones previously obscured by
fundamental modes.  The coefficients constrain mantle
structures of both even and odd spherical harmonic degrees,
through degree 12 in some cases.  Improvements in accuracy
and precision have been achieved with three innovations:
the development of GSF, an enhancement of the established
spectral fitting technique which incorporates both Coriolis
and structural coupling between multiplets; the application
of GSF to an edited, high signal-to-noise and geographically
diverse data set of more than 4500 seismograms from 33 high
moment earthquakes; and the assignment of coefficient
uncertainties using a Monte Carlo method to simulate the
effects of seismic noise, theoretical errors, and coefficient
covariances.  The results of GSF are assessed by examining
the internal consistency of estimated coefficients and
through comparisons with recent mantle models.  The new
catalogue of structure coefficients and uncertainties is
available as an electronic supplement to this paper and
through the University of Colorado internet site.   

JGR, v. 103, n. B1, p. 783-810, January 10, 1998