25-years wind wave hindcast for the North Atlantic
Long term high resolution wind wave hindcast over the North Atlantic from 20˚N to 70˚N for the period from 1989 to 2013 has been developed with the third generation spectral wave model WaveWatch III in conjunction with the non-hydrostatic mesoscale NWP system WRF (Weather Research and Forecasting). The results were verified against buoys and satellite altimetry data.
Analysis of interannual variability of significant wave height based on the hindcast reveals negative significant trend in the Northeast Atlantic (both for mean and extreme characteristics) and in the eastern subtropics.
In the present study, we focused on understanding of variability in the significant wave height in the terms of probability density distributions of this characteristic using 2-parametric Weibull distribution. It effectively describes statistical properties of waves and fits well with observed and modelled probability of occurrence of wind and waves in most areas.
Probability distributions of waves and surface wind are strongly dominated by the shape parameter of Weibull distribution in the tropics with the scale parameter playing the major role in the mid and subpolar latitudes. In the period from 1989 to 2013 trends in the shape parameter of Weibull distribution are positive in the Labrador Sea and the Central midlatitude North Atlantic, which implies decreasing occurrence of high waves in these regions and negative in the subtropics and in the subpolar latitudes, implying growing occurrence of high waves. This result is consistent with the pattern of changes in statistical characteristics of surface winds.