Life cycle
The characteristics of ocean surface (or gravity) waves are determined by the combination of wind speed, wind area (fetch) and their duration. The synoptic conditions over the North Atlantic in mid-April 2012, with high speed winds acting on the ocean’s surface in a large area and over a long period of time (days), favor the generation of a swell with high waves.
ECMWF wave model (WAM) analysis support the occurrence of high waves (Fig. 8) between Newfoundland and the British Isles on 17 and 18 April, with SWH values above 8 m. This region matches perfectly with the location of the fetch (the area from which waves are generated by strong winds with near-constant direction). In the subsequent days, the swell propagated in southeasterly direction, and on 19 and 20 April these waves approached the shores of the Bay of Biscay and the west Iberian coast, with amplitudes around 7 and 5 m, respectively.
Fig.8. ECMWF wave model analysis for 00:00 UTC on 17 April (a), 18 April (b), 19 April (c) and 20 April (d).