Periodicity in Sea Roughness and Origin of Microseisms

Abstract

VARIOUS workers have tried measuring the roughness of the sea by observing wave heights at a particular position as well as by compiling wave profiles along large distances by air observations. Glitter photographs of the sea surface have also been statistically analysed for finding the relation between development of wavelets and wind velocity. It has been recognized that description of sea roughness is very difficult by any of the above means. On the other hand, it is well known that radar clutter increases in amplitude with sea roughness, and estimation of sea roughness should be possible by observations of radar clutter. Recently, one aspect of analysis of sea roughness became imperative in view of the hypothesis that microseisms may be caused by means of interaction of wind and sea roughness. According to such ideas, the periods observed in microseisms should correspond to any autocorrelativ periods in sea roughness.