Effect of ice cover on wave statistics and wave-driven processes in the northern Baltic Sea

We explore the effect of sea ice on wind wave statistics and wave-driven hydrodynamic loads in a seasonally ice-covered sea. We compare the results of hypothetical ice-free wave simulations for 1979-2007 in the northern Baltic Sea with in-situ wave time series and with truncated simulations in which waves during the ice season are ignored. The ice cover impacts the mean wave properties usually less than 5% and up to 10-20% at a few locations. The cumulative annual wave energy and energy flux are greatly (up to 82%) influenced. The mean wave properties and the ice season duration are almost uncorrelated in the Sea of Bothnia and Bay of Bothnia but have a statistically significant (at a > 99% level) negative correlation at the latitudes of the Gulf of Finland. This feature implies that climate-driven changes, first of all, the later appearance of ice in the relatively windy late autumn and winter season, may considerably add energy to coastal processes at these latitudes.