INTERANNUAL VARIATIONS AND LONGER-TERM CHANGES IN THE SEA STATE OF THE NORTH-ATLANTIC FROM 1970 TO 1982

A 13-year (1970-1982) time series of 12-hourly wave charts of the North Atlantic has been analyzed for variations in the sea state. Two types of variation were determined: first, strong 3- to 7-year fluctuations; second, a continuous increase in the sea state during the 13 years. It appears that the former is the result of variations in cyclonic activities over the western North Atlantic, and that the latter is caused by a steady increase in the strength of the prevailing westerly winds. The existence of such fluctuations and changes in the wave activity will affect long-term predictions and are expected to have an important impact on the upper-level physical, chemical, and biological processes of the ocean.