Variations in wave conditions in Estonian coastal waters from weekly to decadal scales

Historical visual observations and numerical hindcasts with the use of the WAM wave model and adjusted geostrophic winds are merged to reveal the basic features of the wave properties and to identify the variations in wave height in different scales in the coastal waters of Estonia. The visually observed wave properties from Vilsandi (1954-2008), Pakri (1954-1985) and Narva-Joesuu (1954-2008) are compared against wave data hind-cast for the entire Baltic Sea for 1970-2007. It is shown that the wave height follows the seasonal variation in wind speed with a maximum in October January and with a substantial variability on weekly scales. The annual mean wave heights reveal nearly synchronous interannual variations along the entire coast of Estonia until the mid-1980s after which this coherence is lost. The length of the ice season is almost uncorrelated with the annual mean wave heights.