Abstract
We analysed the variability of the linear decadal sea-level trends in the Baltic Sea over the past 100
years and their connections to trends in the sea-level-pressure (SLP) field. The analysis is limited to
the December-to-February season. We use means of tide gauges from the Permanent Service for
Mean sea level and monthly gridded Sea Level Pressure (SLP) covering the North Atlantic/European
sector from the University of Colorado. To select the tide gauges, we took into account the
geographical distribution and record length retaining Helsinki, Ratan, Stockholm, Kungsholmsfort,
Smogen, Travemunde, Wismar, Warnemunde and Klaipeda. The linear decadal trends were
calculated over gliding 11-year windows of the tide gauges and the SLP grid records. After computing
the decadal gliding trends, we focused on the correlation patterns between each individual tide
gauge and the SLP for every grid separately.
The results show that the tide gauges can be classified into two groups according to their correlation
with the SLP trends. Helsinki, Ratan, Stockholm, Kungsholmsfort, Smogen and Klaipeda display
resembling correlation patterns that have high positive correlation at the south and negative
correlation at the north, with the zero line approximately located at 50 N, and is thus similar to the
typical pattern of the North Atlantic Oscillation. However, Travemunde, Wismar and Warnemunde,
which are located at the southern Baltic Sea coast, display a rather different pattern that shows
negative correlations over the Baltic Sea region, and negligible correlations elsewhere.
The main implication of this study is that the estimation of the possible acceleration of sea-level and
of its statistical significance has to take into account that the variability of decadal sea-level trends
seems to be controlled by very different atmospheric circulation factors, even in this small region.
