Studies of Ocean Tides with Satellite Altimetry

Edward Zaron - (Oregon State University)

Co-Investigator(s):

Gary Egbert (Oregon State University)

Collaborator(s):

Richard Ray (NASA Goddard Space Flight Center)

Abstract:

This project will study of ocean surface tides and internal tides with satellite altimeter data, other types of data, and numerical models. We will continue producing highly-accurate tidal atlases useful for computing altimeter tide corrections, for both the barotropic and baroclinic tides, and we will disseminate these atlases to facilitate our own and others’ scientific investigations.

Our plan of research involves two parallel lines of work on barotropic and baroclinic tides. For the barotropic tides we will use a global data set of currents derived from Lagrangian surface drifters to assess the model performance and guide its improvement, with largest gains expected on continental shelves and in shallow water. We will also make other improvements to the barotropic model solutions by incorporating altimeter-derived estimates for a number of smaller tides, which were previously ignored or computed by inference from the major tides. Consideration of these tides are expected to lead to significant improvements in tidal predictions in coastal regions where the minor tides are amplified by near-resonant geometries or generated by nonlinear interactions.

Our work on baroclinic tides is aimed at better quantifying the partition between phase-locked and nonphase-locked components of the baroclinic tide, a topic of relevance to both tidal prediction and ocean energetics. Substantially more data and better processing techniques are now available to revisit some previous estimates of the non-phase-locked variability, which we will pursue. We will also apply a new analysis technique to identify the baroclinic waves from altimetry which should provide more precise estimates of their wavelength from shorter records, and enable the inference of subsurface stratification from altimetry. We will also conduct diagnostic studies of baroclinic tidal energetics, which provide useful constraints on recent parameterizations of tidally-driven ocean mixing used in ocean general circulation models.

In addition to the above, we propose to support the OSTST with calibration and validation efforts for the Sentinel-6 mission through intercomparison with other mission data in coastal regions with prominent tidal signals. We will also analyze the high-frequency sea surface height and significant wave height data from Sentinel-6 to verify aspects of the performance of the waveform retracker from the SAR-mode altimeter.

Supported by NOAA