Earth’s rotation: observations and theory - Earth Dynamics: Deformations and Oscillations of the Rotating Earth - page 322

Tabl e 4 . 5 Free decay parameters of the PFCN and RFCN ring downs.
c 10 − 4 d A N 0 (μas) Q N Q W t 1/2 (days)

PFCN
− 1.14877 2.3881 244.40 30.596 11879 2620.45

RFCN
− 1.35076 2.6179 414.86 24.198 10152 2228.60

allowing solution for Q N and τ, and the half-life t 1/2 = τln 2. The intercepts of the

fitted straight lines yield

=

d log A N 0 . (4.134)

The wobble Q W , reflecting the viscosity at the top of the fluid outer core, can then
be recovered via relation (4.129). The free decay parameters recovered from the
ring downs of the PFCN and the RFCN are listed in Table 4.5.