Articles | Volume 8, issue 4
Research article
20 Dec 2017
Research article |  | 20 Dec 2017

Interannual variability of mean sea level and its sensitivity to wind climate in an inter-tidal basin

Theo Gerkema and Matias Duran-Matute

Abstract. The relationship between the annual wind records from a weather station and annual mean sea level in an inter-tidal basin, the Dutch Wadden Sea, is examined. Recent, homogeneous wind records are used, covering the past 2 decades. It is demonstrated that even such a relatively short record is sufficient for finding a convincing relationship. The interannual variability of mean sea level is largely explained by the west–east component of the net wind energy, with some further improvement if one also includes the south–north component and the annual mean atmospheric pressure. Using measured data from a weather station is found to give a slight improvement over reanalysis data, but for both the correlation between annual mean sea level and wind energy in the west–east direction is high. For different tide gauge stations in the Dutch Wadden Sea and along the coast, we find the same qualitative characteristics, but even within this small region, different locations show a different sensitivity of annual mean sea level to wind direction. Correcting observed values of annual mean level for meteorological factors reduces the margin of error (expressed as 95 % confidence interval) by more than a factor of 4 in the trends of the 20-year sea level record. Supplementary data from a numerical hydrodynamical model are used to illustrate the regional variability in annual mean sea level and its interannual variability at a high spatial resolution. This study implies that climatic changes in the strength of winds from a specific direction may affect local annual mean sea level quite significantly.

Short summary
Local mean sea level often varies strongly from year to year (on the order of a few decimeters). This is mainly due to interannual variability in wind climate and atmospheric pressure. In this paper, regional differences in the sensitivity of mean sea level to atmospheric forcing are studied in an inter-tidal basin. Correcting for the atmospheric effects removes most of the interannual variability in mean sea level.
Final-revised paper