Tidal fluctuations in water heigh and currents induce retrograde
diurnal variation of equatorial oceanic angular momentum (OAM), hence small
perturbation on nutation at the level of 1 mas. Most important contribution
comes from water height variations.
Model MHB 2000 (Mathews,
Herring, Buffett, "Modeling of nutation and precession : new nutation series
for non-rigid Earth and insights into the Earth's interior", J.G.R.,
vol. 107, NO B4 (2002), Table 5).
This model is based upon the Oceanic Tidal Angular Momentum model of Chao et
al. (1996) [Diurnal/semidiurnal polar motion excited by oceanic tidal angular
momentum variations, JGR
, 20151-20163]. Effects on nutation
in longitude Δψ and nutation in obliquity Δε refered to ecliptic of date are modelled as a sum a circular terms,
prograde and retrograde :
Δψ sin ε0
+ i Δε = Σj
+ i aopj
) ei (θj
is integer linear combination of Delaunay arguments:
= a1 l + a2 l' + a3 D + a4 F + a5 Ω.
Total effect and separate contributions of matter term and current term are presented in the table here-below: