Surf beats: sea waves of 1 to 5 min. period

Abstract

Long sea waves with periods of 2 to 3 min. and a few inches in amplitude have been measured. It has been shown that they are due to the varying height of groups of waves breaking on the shore. The amplitude of the long waves is found to be approximately proportional to the amplitude of the ordinary waves and independent of their period. The mechanism by which they are produced is discussed.