THE FEASIBILITY OF NORMAL-MODE CONSTRAINTS ON HIGHER DEGREE STRUCTURES

Case studies of four multiplets (upsilon(s)-sensitive S-1(7) and S-1(8 ) and upsilon(p)-sensitive S-5(5) and S-5(6)) are considered to test t he accuracy of normal mode constraints on aspherical structure at degr ees above 2 (4,6,8). Analyses of misfit, along-branch consistency, and consistency with existing mantle models argue for the feasibility of constraints on higher structural degrees. Preliminary interpretation i ndicates a relative insensitivity of data misfits to dln upsilon(p)/dl n upsilon(s) at degrees 6 and 8 in the lower mantle (perhaps due to in accuracies in current delta upsilon(s) models), and provides weak evid ence of some decorrelation between delta upsilon(s) and delta upsilon( p) in the middle and lower mantle.