Climatology, variability and extrema of ocean waves: The web-based KNMI/ERA-40 wave atlas

The European Centre for Medium-Range Weather Forecasts (ECMWF) has recently finished ERA-40, a reanalysis covering the period September 1957 to August 2002. One of the products of ERA-40 consists of six-hourly global fields of wave parameters, like significant wave height and wave period. These data have been generated with the centre's WAM wave model. From these results we have derived climatologies of important wave parameters, including significant wave height, mean wave period, and extreme significant wave heights. Particular emphasis is on the variability of these parameters, both in space and time. Besides being important for scientists studying climate change, these results are also important for engineers who have to design maritime constructions. This paper describes the ERA-40 data and gives an overview of the results derived. The results are available on a global 1.5 degrees x 1.5 degrees grid. They are accessible from the Web-based KNMI/ERA-40 wave atlas at http://www.knmi.nl/waveatias. Copyright (c) 2005 Royal Meteorological Society.