Analyses of Year-to-Year Variation and Trend for Wave Climatic Parameters along the Coasts of Japan Using Long-Term Measurement Data

Abstract

Wave measurement data acquired over more than two decades along the coasts of Japan and the Pacific coast of USA are analyzed from three points of view (1) year-to-year variation, (2) jumps and (3) trends for wintertime- and summertime-meanvalues of significant wave height and period. Main findings are as follows:(1) the winter of 1998, containing the severest El-Nino period, gives the highest mean wave height along the western Pacific coast of Japan and the Pacific coast of USA.(2) a seesaw-like variation with a two-year period of season-separated meanwave heights along the Pacific coast of Japan may be observed and (3) one jump and an increasing trend in summer-time mean wave period data may be observed along the coasts of Japan.