• Tidal levels are influenced by a combination of astronomical tides and other meteorological and hydrodynamic forcings, such as wind-driven storms. Among these, the most prominent and easiest to predict are the astronomical tides, as it refer to the periodic rise and fall of sea levels caused primarily by the gravitational forces exerted by the Moon and the Sun, in combination with the Earth's rotation. For the other influences, hydrodynamic simulations with numerical weather predictions are required (e.g. glossis). 
  • Astronomical tides can be described using a series of tidal constituents. For example, NOAA publish these constituents online: Station Selection - NOAA Tides & Currents
  • These constituents are obtained by performing frequency decomposition, aka Harmonic analysis on a long observation record of tidal data (e.g. a few years).
  • There are open source toolbox available for conducting harmonic analaysis. A really good one is the T_Tide: R. Pawlowicz, B. Beardsley, and S. Lentz, "Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE", Computers and Geosciences 28 (2002), 929-937. https://www-old.eoas.ubc.ca/~rich/#T_Tide. Tips: The mean depth is included in the tidal continents as A0. 
  • When a long observation record is not available/quality does not suffice, one can make use of reanalysis data, such as https://cds.climate.copernicus.eu/datasets/sis-water-level-change-timeseries-cmip6?tab=overview). 
  • Once the tidal constituents have been identified, they can be used to generate astronomical tides for any given time through a straightforward transformation in Delft-FEWS (https://publicwiki.deltares.nl/display/FEWSDOC/GenerationTidalConstituents+Transformation).
  • (Deltares only) Astronomical tides from an extensive global dataset are available via contact person Bob van Rongen.

  • No labels

Disclaimer