Infragravity wave

The most common process is the subharmonic interaction of trains of wind waves which was first observed by Munk and Tucker and explained by Longuet-Higgins and Stewart.

The waves also push the water around in a way that can be interpreted as a force: the divergence of the radiation stresses.

Combining mass and momentum conservation, Longuet-Higgins and Stewart give, with three different methods, the now well-known result.

The details of this process are modified when the bottom is sloping, which is generally the case near the shore, but the theory captures the important effect, observed in most conditions, that the high water of this 'surf beat' arrives with the waves of lowest amplitude.

[9] Infragravity waves generated along the Pacific coast of North America have been observed to propagate transoceanically to Antarctica and there to impinge on the Ross Ice Shelf.

Classification of the spectrum of ocean waves according to wave period . [ 3 ]
Surf can be seen breaking as it crosses the sand bar offshore. Sandbars aid in generating infragravity waves and in turn are shaped by them.
Ice shelf processes.