Variation of sea level trends along the coast of the Gulf of Finland

Abstract

Historical time series of monthly mean values of sea level were compiled for all stations in the Gulf of Finland for time periods starting from the beginning of sea level observations at each station and until station closing, or the year 2005 for Russian, 2004 for Finnish and 1991 for Estonian stations. These data were analysed for trends for a common period from 1920 till 1991. It was found that along the northern coast of the Gulf of Finland, the sea level trends change from minus 3-4 mm/year along the western part of this coast (at Turku and Hanko) to plus 1,5 mm/year along the eastern part of the coast (at Lisiy Nos). Along the southern coast of the Gulf of Finland, the sea level trends change from west to east (from station to station) not as regularly as along the northern coast. However, trend values along the southern coast are considerably less than along the northern coast. It was therefore concluded that within the limits of errors of trend calculations, the sea level trends along the southern coast also change from small negative values in the west (at Ristna, Poosaspea) to plus 1,4 mm/year in the east (at Lomonosov). At the head of the Gulf (at Port of Nevskaya), the positive trend was the largest: 3,3 mm/year. Relative to the global sea level rise (about 2 mm/year during the last century) trend values are negative in all points except Saint Petersburg. Their spatial distribution is consistent with the map of post-glacial uplift in Fennoscandia (Ekman, 1996).