Changes in the North Pacific wave climate since the mid‐1990s

Abstract

AbstractSince the mid‐1990s, ocean wave reanalysis and in situ wave observations have revealed marked downward trends in wave height, exceeding −0.1 m per decade in the midlatitude North Pacific. The wave period in the tropical Pacific is also on a downward trend, exceeding −0.4 s per decade during this period. These changes in wave climate in the Pacific are attributable to recently strengthened trade winds and La Niña‐like conditions in the tropical Pacific. The downward trend in significant wave height in the midlatitude North Pacific is due to strengthening of the negative phase of the Pacific‐North American teleconnection. Numerical experimentations with a wave model also showed that the downward trend in the wave period in the eastern equatorial Pacific was induced not only by increased wind waves due to strengthened trade winds but also by weakened propagating swells from the midlatitude North Pacific.