On the estimation of return values of significant wave height data from the reanalysis of the European centre for medium-range weather forecasts

The Peaks-Over-Threshold method is used to obtain return value estimates from buoy and reanalysis (ERA-40) significant wave height data. The large amount of data used in this study provides evidence for the significant wave height data having an exponential tail, which simplifies the estimation process. Comparisons between buoy and ERA-40 return value estimates show that the ERA-40 data can be reliably,used to obtain return value estimates once a simple linear correction is applied. Further, we assess the effect of the significant wave height's space and time variability on the prediction of the extreme values. This is done by performing detailed global extreme value analyses using different subperiods of the 45-year long ERA-40 dataset.