Extreme wave climate changes in Central-South America

The spatial and temporal variability of extreme wave climate along the Central-South American continent is analyzed. The study evaluates changes in the intensity of extreme significant wave height (SWH) throughout the year over the 1980-2008 period, using a calibrated long-term wave reanalysis database forced with NCEP/NCAR reanalysis. A non-stationary extreme value model, based on monthly maxima with a new approach for long-term trends, has been applied. Results show a common positive trend in the Pacific basin throughout all seasons and a significant decreasing trend pattern in the area of Surinam and north of Brazil, on the Atlantic border (up to -1.5 cm/year in March-April-May). A higher increase of the extreme wave heights is found in the austral summer (December-January-February) at Tierra de Fuego and the Falkland Islands, reaching 6.5 cm/year (which means 1.82 m for the 28 years studied). Furthermore, the complete reanalysis period (1948-2008) is analyzed in order to compare results with the assimilation data period (1980-2008), resulting in some discrepancies, especially in the Atlantic basin.