Egbert, G. D., Oregon State University, Corvallis, USA, egbert@coas.oregonstate.edu
Ray, R. D., GSFC/NASA, Greenbelt, USA, richard.ray@nasa.gov

PROSPECTS FOR TIDAL STUDIES WITH HIGH-RESOLUTION ALTIMETRY

Altimetry data from the TOPEX/Poseidon and Jason-1 missions have allowed tidal elevations in the open ocean to be mapped to high accuracy--even minor constituents such as M4 (with open ocean amplitudes measured in mm) can now be reliably determined with the long timeseries available. However, many tidal phenomena remain poorly constrained by the coarse spatial sampling of a traditional nadir altimeter. For example, internal tides are clearly seen in the altimetry data radiating away from generation sites over rough topography in the deep ocean. However, wavelengths are ~100 km or less, and are thus poorly sampled by a nadir altimeter. Model simulations show that maps of internal tide energy flux constructed from T/P data significantly underestimate actual fluxes. Increasing the sampling density (e.g., by using tandem mission data) increases the mapped fluxes. However, accurate mapping, which may shed light on tidal mixing and energy dissipation in the deep ocean, would require almost complete spatial coverage. Challenges also arise with the surface tides in shallow coastal seas, where spatial wavelengths are much shorter than typical altimeter track spacings, and frequency spectra are often more complex due to the presence of non-linear constituents. Future technologies that provide nearly continuous coverage and extend close to the actual coast would greatly improve our ability to map tidal elevations and currents, in these areas of great societal importance.

Oral presentation

Presentation is given by student: No
Session #:006
Date: 03-05-2008
Time: 14:30