“If the disturbance motion is the dominant motion, the meaning of ‘displacement’ is fairly obviousab initioand is such that if [the Eulerian mean] is the time mean at a fixed point, then [the Lagrangian mean] is the time mean following a single fluid parcel, at least approximately.” (p. 131)

“The classical Lagrangian-mean motion is evidently divergent; and it can be shown directly from (12) [Taylor expansion of the Stokes correction] that the effect is O(a*^2) and therefore comparable with all other mean effects of the waves even when their amplitude *ais arbitrarily small”

**Question**: So why Moore (1970) proves that the Lagrangian-mean flow is nondivergent?