Studies of Ocean Surface Tides and Internal Tides with Satellite Altimetry
- (NASA Goddard Space Flight Center)
This proposal builds on our current OSTST investigation, studying ocean surface tides and internal tides with satellite altimeter data, other types of data, and numerical modeling and assimilation. We propose to continue to produce highly-accurate global tidal atlases by multi-satellite empirical mapping as well as data assimilation. These will include some experimental solutions that specifically address problems related to
TOPEX/Poseidon and Jason altimetry, including the 59-day error in global mean sea level, as well as minor constituents which have been traditionally neglected.
Two major additional thrusts of this investigation are
In the sixteen years since we (Egbert and Ray) deduced barotropic dissipation from T/P altimetry, our tidal elevation fields have improved markedly. It is thus timely to revisit the subject, with a goal toward reducing noise levels and increasing spatial resolution. Combined with an assessment of baroclinic energy-flux divergence, determined from our multi-satellite mapping of the baroclinic tide, and our growing understanding of baroclinic tidal coherence, the dissipation estimates place constraints on the amount of energy available for ocean mixing. We propose to concentrate especially on locations of about two dozen major ocean mixing experiments, recently reviewed by Waterhouse and colleagues; our tidal-energy estimates should place tighter constraints on their interpretations. An ultimate goal of such work is to help the community improve mixing parameterizations needed in ocean-circulation and climate models.
Our efforts toward improved tidal models help nearly all other altimeter users, and indeed the much wider geodetic, geophysical, and oceanographic communities. Further extension to some very small constituents (e.g., terdiurnal tides) will clarify how the ocean responds to different, but exactly known, forcing. Incorporation of small waves like M3 could also help other geodetic missions such as GRACE.
Finally, we propose to support the OSTST in its calibration and validation efforts with the new Jason-3 data and to help lay the foundations for high-resolution altimetry expected from both Jason-CS/Sentinel-6 and SWOT.