Lowest Astronomical Tide in the North Sea Derived from a Vertically Referenced Shallow Water Model, and an Assessment of its Suggested Sense of Safety
- 8 January 2013
- journal article
- research article
- Published by Taylor & Francis Ltd in Marine Geodesy
- Vol. 36 (1), 31-71
- https://doi.org/10.1080/01490419.2012.743493
Abstract
Water level reduction with global navigation satellite systems in bathymetric surveying requires knowledge of the ellipsoidal heights of lowest astronomical tide (LAT). The traditional approach uses tidal water levels of an ocean tide model, which are subtracted from mean sea level (MSL). This approach has two major drawbacks: the modeled water levels refer to an equipotential surface, which differs from MSL, and MSL may not be known close to the coast. Here, we propose to model LAT directly relative to an equipotential surface (geoid). This is conceptually consistent with the flow equations and allows the inclusion of temporal MSL variations into the LAT definition. Numerical experiments for the North Sea show that significant differences between the traditional and the pursued approach exist if average monthly variations in MSL are included. A validation of the modeled LAT using tide gauge records reveals systematic errors, which we attribute to both the model and the tidal analysis procedure. We also show that the probability that water levels drop below LAT is high, with maximum frequency of once per week in the eastern North Sea. Therefore, we propose to reconsider the deterministic concept of LAT by a probabilistic chart datum concept, and we quantified the differences between them.Keywords
This publication has 41 references indexed in Scilit:
- Versatile Harmonic Tidal Analysis: Improvements and ApplicationsJournal of Atmospheric and Oceanic Technology, 2009
- An Oceanographer's Guide to GOCE and the GeoidOcean Science, 2008
- Comparison of Ocean Dynamics with a Regional Circulation Model and Improved Altimetry in the North-Western MediterraneanTerrestrial, Atmospheric and Oceanic Sciences, 2008
- Modelling the global ocean tides: modern insights from FES2004Ocean Dynamics, 2006
- Operational storm surge forecasting in the Netherlands: developments in the last decadePhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2005
- An s coordinate density evolving model of the northwest European continental shelf: 1. Model description and density structureJournal of Geophysical Research: Oceans, 2001
- An s coordinate density evolving model of the northwest European continental shelf: 2. Seasonal currents and tidesPublished by American Geophysical Union (AGU) ,2001
- Geodetic Reference System 1980Journal of Geodesy, 2000
- Atmospheric loading and the oceanic “inverted barometer” effectReviews of Geophysics, 1997
- Impacts of geodynamic phenomena on systems for height and gravityJournal of Geodesy, 1989