PHD DEFENSE: « Realistic internal tides modeling: surface signature, variability and energy budget »

– Simon BARBOT – Soutenance de thèse – LEGOS, Toulouse, France –

Jury:

Sarah Gille                    Reviewer
Nicolas Grisouard         Reviewer
Guillaume Charria         Reviewer
Chantal Staquet            Examinator
Brian Arbic                    Examinator
Florent Lyard                 PhD advisor
Loren Carrere                PhD advisor

Abstract:

The internal tides are generated when the barotropic tidal currents frontally intercept a significant bathymetric slope in a stratified ocean context, creating a periodic displacement of the ocean layers. The baroclinic pressure anomalies generated there propagate as internal waves over distances up to 2000 km, impacting the entire water column. The forthcoming mission SWOT especially needs the understanding of the internal tides because its 21-days orbit will not allow to discriminate the spatio-temporal scales of the internal tides from the ones of the mesoscale and sub-mesoscale.

The stationary surface signal of the internal tides is already well described, but the non-stationary surface signal, mainly due to the variability of ocean circulation and stratification, must be addressed by different methodologies. This present thesis participates to better define the mechanisms responsible for the non-stationarity and particularly due to the temporal variability of the stratification.

First, the stratification conditions are defined using an innovative classification of in situ density profiles with a clustering method, allowing to represent the stratification variability from a reduced number of typical profiles. From these profiles, the internal tides are simulated in an idealized case using the T-UGO frequency domain model, then in a semi-realistic case of the Bay of Biscay using the SYMPHONIE model. Second, the altimetry time series are analyzed according to a seasonal partition, consistent with the classification of the stratification conditions, allowing the comparison to the semi-realistic modeling. This partition challenges the robustness of the harmonic analysis methods traditionally used for the tide, so this thesis explores a numerical method and its limitations.

[ Lien online – https://cnrs.zoom.us/j/92727513991?pwd=UGU3MkdjVzRqUUtXLzR1Vi8rVVkrdz09 ]

Meeting ID: 927 2751 3991
Passcode: thesis1515