The feasibility of normal mode constraints on higher degree structures

Case studies of four multiplets (υ s ‐sensitive 1 S 7 and 1 S 8 and υ p ‐sensitive 5 S 5 and 5 S 6 ) are considered to test the accuracy of normal mode constraints on aspherical structure at degrees 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 indicates a relative insensitivity of data misfits to dlnυ p /dlnυ s at degrees 6 and 8 in the lower mantle (perhaps due to inaccuracies in current δυ s models), and provides weak evidence of some decorrelation between δυ s and δυ p in the middle and lower mantle.