Contribution of Atmospheric Teleconnections in Regional Wave Climate Variability Based on EOF Application: Baltic Sea Case
Abstract
Climate change has a noticeable impact on increasing wave heights and storm surges which lead to more hazards and menaces in coastal areas. Moreover, in fetch-limited basins like the Baltic Sea and the Great Lakes, even small changes in the wind properties cause large spatiotemporal variations of the wave conditions. Therefore, it is crucial to identify what the main drivers behind the wave climate changes are to diminish the future threats to coastal areas. To understand the variability of wave heights, the technique of Empirical Orthogonal Functions (EOF) was applied to the multi-mission satellite altimetry data in 1992-2015, which were extensively validated against the in-situ data. An increase in wave heights was detected predominantly in the western part of the Baltic Sea, revealing a prominent meridional pattern: an increase in the central and western parts of the sea and a decrease in the east. This pattern is likely caused by a rotation of wind directions rather than by an increase in the wind speed. The validity of the pattern was confirmed by performing simulations of the satellite altimetry data for different scenarios of wave height variability. The winter trends show a statistically significant negative correlation of -0.47±0.19 with the Scandinavian mode (SCAND) and a positive correlation with the North Atlantic Oscillation (NAO) (0.31±0.22) and the Arctic Oscillation (AO) (0.42±0.20). North-westerly and westerly winds are driven by the SCAND and NAO, respectively, and cause the observed meridional pattern. We demonstrate that the winter trends in the Baltic Sea wave heights are driven by the SCAND together with the NAO and the AO. We have also detected a statistically significant time variability of this correlation. When the influence of the SCAND pattern is strong, the effects of NAO and AO are low and vice versa. We demonstrate that the increase in the wave heights in the Baltic Sea is caused by the interplay of these three teleconnections.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMOS0470002N
- Keywords:
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- 4504 Air/sea interactions;
- OCEANOGRAPHY: PHYSICAL;
- 4512 Currents;
- OCEANOGRAPHY: PHYSICAL;
- 4520 Eddies and mesoscale processes;
- OCEANOGRAPHY: PHYSICAL;
- 4560 Surface waves and tides;
- OCEANOGRAPHY: PHYSICAL