Towards area-wide operational tide predictions for the German Bight

Abstract

The German Federal Maritime and Hydrographic Agency (BSH) operates the Tidal Information Service that is responsible for producing and publishing tidal predictions for German waters. Traditionally, the predictions are produced for tide gauge locations, which are situated almost exclusively at or close to the coastline. Water level observations from the tide gauges are used as input data for the respective tidal analyses. BSH strives to extend these point-wise predictions to an area-wide data set for the German Bight based on simulated water levels. This shall serve the increasing demands in the context of research, shipping and offshore activities. High quality area-wide tidal data might also be usable for the reduction of measurements from satellite altimetry in this region.We present tidal analyses based on simulated water levels using the hydrodynamic-numerical model HBM. This model runs operationally at BSH. Many grid points that cover the Wadden Sea run dry around low water and require special attention in the analyses. Tidal parameters, such has the mean lunitidal intervals and tidal ranges, are compared with data from tide gauges. One challenge is the harmonisation of tidal predictions based on model data with those based on tide gauge observations, in order to produce consistent products. The results from this work could also help to improve the implementation of tides in HBM in the future.