24 Oct 2022
 | 24 Oct 2022

Validating the spatial variability of the semidiurnal internal tide in a realistic global ocean simulation with Argo and mooring data

Gaspard Geoffroy, Jonas Nycander, Maarten C. Buijsman, Jay F. Shriver, and Brian K. Arbic

Abstract. The total variance and decorrelation of the semidiurnal internal tide (IT) are examined in a 32-day segment of a global run of the HYbrid Coordinate Ocean Model (HYCOM). This numerical simulation, with 41 vertical layers and 1/25 degree horizontal resolution, includes tidal and atmospheric forcing allowing for the generation and propagation of IT to take place within a realistic eddying general circulation. The HYCOM data are in turn compared with global observations of the IT around 1,000 dbar, from Argo float park phase data and mooring records. HYCOM is found to be globally biased low in terms of total variance and decorrelation of the semidiurnal IT over timescales shorter than 32 days. Except in the Southern Ocean, where limitations in the model causes the discrepancy with in situ measurements to grow poleward, the spatial correlation between the Argo and HYCOM inferred total variance suggests that the generation of low-mode semidiurnal IT is globally well captured by the model.

Gaspard Geoffroy et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1085', Anonymous Referee #1, 21 Nov 2022
    • AC1: 'Reply on RC1', Gaspard Geoffroy, 24 Jan 2023
  • RC2: 'Comment on egusphere-2022-1085', Anonymous Referee #2, 07 Dec 2022
    • AC2: 'Reply on RC2', Gaspard Geoffroy, 24 Jan 2023

Gaspard Geoffroy et al.

Gaspard Geoffroy et al.


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Short summary
The ocean state is sensitive to the mixing originating from internal tides (IT). To date, our knowledge of the magnitude and spatial distribution of this mixing mostly relies on uncertain modeling. Here, we use novel observations from autonomous floats to validate the spatial variability of the semidiurnal IT in a realistic ocean simulation. The numerical simulation is found to correctly reproduce the main spatial patterns of the observed tidal energy, but to be biased low at the global scale.