Singular Spectrum Analysis of Baltic Sea ice conditions and large-scale atmospheric patterns since 1708

We examine the relationship between ice conditions in the Baltic Sea and th e large-scale atmospheric circulation patterns that create them. Singular S pectrum Analysis (SSA) is used to extract long-term trends and quasi-regula r oscillations from time series of winter air temperature, date of ice brea k-up, maximum annual ice extent in the Baltic Sea (BMI) since 1708 and seas onal North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) indices. The AO exhibits power at periods of 2.3 and 13.9 years as well as at 7.8 ye ars, and in general the NAO can be viewed as a subset of the AO as regards the Baltic region. Time series of ice break-up date also reflects variation s in winter AO power in the 13.9-year power band, but not in the NAO 7.8-ye ar band. The BMI seems to act as a non-linear filter on the fairly weak cli mate oscillations, increasing the signal-to-noise ratio of the oscillations significantly.