Improved estimates of mean sea level changes in the German Bight over the last 166 years

In this paper, mean sea level changes in the German Bight, the south-eastern part of the North Sea, are analysed. Records from 13 tide gauges covering the entire German North Sea coastline and the period from 1843 to 2008 have been used to derive high quality relative mean sea level time series. Changes in mean sea level are assessed using non-linear smoothing techniques and linear trend estimations for different time spans. Time series from individual tide gauges are analysed and then 'virtual station' time series are constructed (by combining the individual records) which are representative of the German Bight and the southern and eastern regions of the Bight. An accelerated sea level rise is detected for a period at the end of the nineteenth century and for another one covering the last decades. The results show that there are regional differences in sea level changes along the coastline. Higher rates of relative sea level rise are detected for the eastern part of the German Bight in comparison to the southern part. This is most likely due to different rates of vertical land movement. In addition, different temporal behaviour of sea level change is found in the German Bight compared to wider regional and global changes, highlighting the urgent need to derive reliable regional sea level projections for coastal planning strategies.