Treatment of ocean tide aliasing in the context of a next generation gravity field mission

Abstract : Ocean tides are noise to those who wish to construct the ocean geoid using satellite altimeter data. Precise modeling of the ocean tides will help improve the geoid modeling accuracy. This report stuidies whether altimeter data itself can be used to assess various tide models. The Schwiderski Global Tide Model and the Kuo Pacific Ocean tide model were examined using SEASAT altimeter data in the Gulf of Alaska and South Pacific region. The NSWC Ocean Tide Model contains nine harmonic partial tides of the semi-diurnal, diurnal, and long-period species. The model includes effects of tide-generated terrestrial and oceanic mass perturbations. The Kuo model is a Pacific Ocean total tide model with earth tide corrections. The method employed here cannot as yet be used to study the long wavelength component of tides removed by the quadratic fits, and only height differences along near-repeat sub-satellite tracks can be studied; if the altimeter repeat ground tracks do not overlap exactly, geoidal variations can not be completely removed by simple subtraction. The precision of satellite altimetry also places a limit on the accuracy with which one can safely assess the error of a tide model. Within these limitations, the feasibility of using altimeter data to assess tide models has been successfully demonstrated. Keywords: Satellite altimetry.

Tide gauge

Ocean tide

Ocean surface topography

Internal tide

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DAROTA - Dynamical and Residual Ocean Tide Analysis for improved GRACE de-aliasing

Christoph Dahle Torsten Mayer‐Gürr R Savcenko Eifu Taguchi W Bosch

Aliasing

Tide gauge

Ocean tide

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EOT10a -a new global ocean tide model from multi-mission altimetry

R Savcenko W Bosch

Satellite Altimetry

Tide gauge

Ocean tide

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Accuracy assessment of global internal-tide models using satellite altimetry

Ocean science (2021)

Loren Carrère Brian K. Arbic Brian D. Dushaw G. D. Egbert Svetlana Y. Erofeeva

Abstract. Altimeter measurements are corrected for several geophysical parameters in order to access ocean signals of interest, like mesoscale or sub-mesoscale variability. The ocean tide is one of the most critical corrections due to the amplitude of the tidal elevations and to the aliasing phenomena of high-frequency signals into the lower-frequency band, but the internal-tide signatures at the ocean surface are not yet corrected globally. Internal tides can have a signature of several centimeters at the surface with wavelengths of about 50–250 km for the first mode and even smaller scales for higher-order modes. The goals of the upcoming Surface Water Ocean Topography (SWOT) mission and other high-resolution ocean measurements make the correction of these small-scale signals a challenge, as the correction of all tidal variability becomes mandatory to access accurate measurements of other oceanic signals. In this context, several scientific teams are working on the development of new internal-tide models, taking advantage of the very long altimeter time series now available, which represent an unprecedented and valuable global ocean database. The internal-tide models presented here focus on the coherent internal-tide signal and they are of three types: empirical models based upon analysis of existing altimeter missions, an assimilative model and a three-dimensional hydrodynamic model. A detailed comparison and validation of these internal-tide models is proposed using existing satellite altimeter databases. The analysis focuses on the four main tidal constituents: M2, K1, O1 and S2. The validation process is based on a statistical analysis of multi-mission altimetry including Jason-2 and Cryosphere Satellite-2 data. The results show a significant altimeter variance reduction when using internal-tide corrections in all ocean regions where internal tides are generating or propagating. A complementary spectral analysis also gives some estimation of the performance of each model as a function of wavelength and some insight into the residual non-stationary part of internal tides in the different regions of interest. This work led to the implementation of a new internal-tide correction (ZARON'one) in the next geophysical data records version-F (GDR-F) standards.

Internal tide

Ocean surface topography

Sea-surface height

Tide gauge

Ocean dynamics

10.5194/os-17-147-2021

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Citations (58)

The treatment of ocean tides in the context of the GOCE satellite mission

E. Hoeck Roland Pail

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