Ice conditions of the Arctic present the most significant hazard that offshore structures located there will encounter. In severe ice environments, ice loads influence size, stability, reliability and durability of engineering structures. In order to calculate ice load and effects from interacting ice features, it is necessary to determine statistical variability of the ice features, and develop probabilistic models of ice conditions. The purpose of this study is to develop the probabilistic model of the ice cover on the Raahe lighthouse in the Gulf of Bothnia, taking into account correlation and statistical dependence of essential factors of ice environment. For the probabilistic analysis and modeling the full-scale observation data of ice regime of an Oulu and Raahe lighthouses zone in the Gulf of Bothnia have been processed for winter seasons of 2005÷2009 years. The result of investigations is the probabilistic model of ice conditions at concrete foundation of Raahe lighthouse for various ice scenarios with a view on correlation and stochastic relationship between observed values of ice parameters.
Ice investigations around lighthouses in the Gulf of Bothnia have been carried out for over 30 years by this time, and they have become more intensive in the last 5÷10 years with application of the up-to-date observation technologies and ice model tests. On this problem, dozens of the ice research programs have been realized and the significant amount of scientific studies and engineering reports from the key ice laboratories and centers has been published. On the basis of analysis of the available publications all the investigations can be divided conventionally as follows. 1. Regular full scale observations of hydrological, meteorological and ice regime of the sea area in the Gulf of Bothnia since 1979 till the present time with subsequent statistical data processing (http://en.ilmatieteenlaitos.fi).