Preprints
https://doi.org/10.5194/egusphere-2024-247
https://doi.org/10.5194/egusphere-2024-247
30 Jan 2024
 | 30 Jan 2024

Internal tides vertical structure and steric sea surface height signature south of New Caledonia revealed by glider observations

Arne Bendinger, Sophie Cravatte, Lionel Gourdeau, Luc Rainville, Clément Vic, Guillaume Sérazin, Fabien Durand, Frédéric Marin, and Jean-Luc Fuda

Abstract. In this study, we exploit autonomous underwater glider data to infer internal tide dynamics south of New Caledonia, an internal-tide generation hot spot in the southwestern tropical Pacific. By fitting a sinusoidal function to vertical displacements at each depth using a least-squares method, we simultaneously estimate diurnal and semidiurnal tides. Our analysis reveals regions of enhanced tidal activity, strongly dominated by the semidiurnal tide. To validate our findings, we compare the glider observations to a regional numerical simulation that includes tidal forcing. This comparison assesses the simulation’s realism in representing tidal dynamics and evaluates the glider’s ability to infer internal tide signals and their signature in sea surface height (SSH). The glider observations and a pseudo glider, simulated using hourly numerical model output with identical sampling, exhibit similar amplitude and phase characteristics along the glider track. Existing discrepancies are primarily explained by tidal incoherence induced by eddy-internal tide interactions. We infer the semidiurnal internal tide signature in steric SSH by the integration of vertical displacements. Within the upper 1000 m, the pseudo glider captures roughly 78 % of the steric SSH total variance explained by the full water column signal. This value increases to over 90 % when projecting the pseudo glider’s vertical displacements onto climatological baroclinic modes and extrapolating to full depth. Notably, the steric SSH from glider observations aligns closely with empirical estimates derived from satellite altimetry, highlighting the glider observations’ predominating coherent nature.

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Arne Bendinger, Sophie Cravatte, Lionel Gourdeau, Luc Rainville, Clément Vic, Guillaume Sérazin, Fabien Durand, Frédéric Marin, and Jean-Luc Fuda

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-247', Anonymous Referee #1, 26 Feb 2024
    • AC1: 'Reply on RC1', Arne Bendinger, 27 May 2024
  • RC2: 'Comment on egusphere-2024-247', Anonymous Referee #2, 16 Apr 2024
    • AC2: 'Reply on RC2', Arne Bendinger, 27 May 2024

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-247', Anonymous Referee #1, 26 Feb 2024
    • AC1: 'Reply on RC1', Arne Bendinger, 27 May 2024
  • RC2: 'Comment on egusphere-2024-247', Anonymous Referee #2, 16 Apr 2024
    • AC2: 'Reply on RC2', Arne Bendinger, 27 May 2024
Arne Bendinger, Sophie Cravatte, Lionel Gourdeau, Luc Rainville, Clément Vic, Guillaume Sérazin, Fabien Durand, Frédéric Marin, and Jean-Luc Fuda

Data sets

Internal tides vertical structure and steric sea surface height signature south of New Caledonia revealed by glider observations Arne Bendinger https://doi.org/10.5281/zenodo.10174169

Model code and software

Internal tides vertical structure and steric sea surface height signature south of New Caledonia revealed by glider observations Arne Bendinger https://doi.org/10.5281/zenodo.10174311

Arne Bendinger, Sophie Cravatte, Lionel Gourdeau, Luc Rainville, Clément Vic, Guillaume Sérazin, Fabien Durand, Frédéric Marin, and Jean-Luc Fuda

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Short summary
A unique data set of glider observations reveal tidal beams south of New Caledonia – an internal tide generation hot spot in the southwestern tropical Pacific. Observations are in good agreement with numerical modeling output highlighting the glider's capability to infer internal tides while assessing the model's realism of internal tide dynamics. Discrepancies are primarily linked to eddy-internal tide interactions. A methodology is proposed to deduce the internal tides surface signature.