Non-linear tides in shallow water regions from multi-mission satellite altimetry (The Northwest European shelf).
Ole Andersen(1) , R. Ray(2) , Lana Erofeeva(3) , and Gary Egbert(3)
Danish National Space Center,
Juliane Maries Vej 30,
Dk-2100 Copenhagen O,
(2) NASA GSFC, Gode 672, 20770 Greenbelt, United States
(3) OSU, Oregon State University, Corvallis, United States
Accurate sea level measurements from the TOPEX/POSEIDON satellite have vastly improved our knowledge about global ocean tide since its launch in 1992. One of the outstanding problems in global tidal modelling is accuracy in shallow water regions, where complex tidal pattern, and non-linear tides degrade the global model. This calls for high resolution tidal modelling and inclusion of non-linear shallow water constituents. These constituents cause a considerable part of the tidal variability on the shelves. On the northwest European shelf the tides are dominated by semi-diurnal constituents and their shallow water constituents (M4, MS4, MNS2, MN4, and M6). One example is the M4 constituent, which exceeds 30 cm in the English Channel.
New tidal models for the non-linear tides have been derived using coastal tide inversion, assimilating multi-mission altimetric observations into high resolution hydrodynamic models. Shallow water tides have shorter spatial wavelength, and the importance of high quality bathymetry and altimetry from both the T/P and the recent interlaced T/P Tandem Mission will be demonstrated