Satellite altimetry reveals spatial patterns of variations in the Baltic Sea wave climate

TL;DR

This study uses satellite altimetry data to analyze the spatial and temporal variations of wave climate in the Baltic Sea, revealing decadal patterns and regional differences linked to wind direction changes.

Contribution

It provides a comprehensive satellite-based analysis of Baltic Sea wave climate, highlighting spatial patterns and decadal variability not previously documented.

Findings

Overall increase in mean significant wave height of 0.005 m per year.

Spatial pattern of wave height changes shows increase in central and western regions, decrease in eastern areas.

Wave height variations are linked to wind direction rotation, not wind speed increase.

Abstract

The main properties of the climate of waves in the seasonally ice-covered Baltic Sea and its decadal changes since 1990 are estimated from satellite altimetry data. The data set of significant wave heights (SWH) from all existing nine satellites, cleaned and cross-validated against in situ measurements, shows overall a very consistent picture. A comparison with visual observations shows a good correspondence with correlation coefficients of 0.6-0.8. The annual mean SWH reveals a tentative increase of 0.005 m yr-1, but higher quantiles behave in a cyclic manner with a timescale of 10-15 yr. Changes in the basin-wide average SWH have a strong meridional pattern: an increase in the central and western parts of the sea and decrease in the east. This pattern is likely caused by a rotation of wind directions rather than by an increase in the wind speed.