Revised Global Wave Number Spectra From Recent Altimeter Observations

Oscar Vergara (1) , Rosemary Morrow (1) , Isabelle Pujol , Gérald Dibarboure (2) , Clément Ubelmann

1 LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales
2 CNES - Centre National d'Études Spatiales [Toulouse]

Global sea surface height wave number spectra are revisited using the most recent, lower-noise satellite altimeter missions from Saral/AltiKa and Sentinel-3 and compared to Jason-2 wave number spectra. Spectral preprocessing is configured to minimize the spectral slope distortion in the mesoscale wavelength range. A geographically variable wavelength range is used to calculate the spectral slopes, taking into account the regional eddy length scales based on the local Rossby radius. This dynamical wavelength range increases the spectral slope by 0.5 in middle to high latitudes, compared to a fixed wavelength range, and by -1.0 to 1.0 in different regions of the intertropical band. Using this dynamical wavelength range, mean sea surface height wave number spectra for these lower-noise missions exhibit low slope values (k^-2) in the intertropical band, values of k^-11/3 in the midlatitudes, and reaches k^-5 in the subpolar regions and the Antarctic circumpolar current. An important seasonality is also revealed, with mesoscale spectral slope amplitudes decreasing in winter by 0.5 to 1.5 compared to summer, for the middle- to high-energy regions. A phase-locked internal tide correction is tested but has only a small impact on the spectral slope estimates when using the dynamical wavelength range.

Mots clés: satellite altimetry; mesoscale variability; energy cascade; internal waves; space oceanography

Domaines: Planète et Univers [physics]; Océanographie

Oscar Vergara, Rosemary Morrow, Isabelle Pujol, Gérald Dibarboure, Clément Ubelmann. Revised Global Wave Number Spectra From Recent Altimeter Observations. Journal of Geophysical Research. Oceans, 2019, 124, pp.3523-3537. ⟨10.1029/2018JC014844⟩. ⟨insu-03670751⟩