“…By writing the Hamiltonian in terms of the mean flow momentum, m, rather than the total momentum, M, we recover the tangled version of the Lie-Poisson Hamiltonian form of the equations. Above, as in [12], we have presented wave-current interaction in its untangled form. In a previous work [11], the authors presented both the tangled and untangled forms, and an analogous calculation is also possible for this model of WMFI.…”