Formation of the Baltic Sea level spectrum

In order to understand the water dynamics of the Baltic Sea, one has to have an idea about the formation of the entire spectrum of the sea level fluctuations with periods from hours to tens of years. According to [3], one can distinguish the following five variability ranges in the classification of the sea level fluctuations with periods smaller than 10 years: mesoscale (from 2 hours to 2 days), synoptic (from 2 days to one month), intra annual (from 1 month to 1 year), seasonal (annual period and divisible harmonics), and interannual (from 1 year to 10 years).