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Data from: A method of separating linear internal wave and vortical mode energies using shipboard ADCP velocity measurements

Vladoiu, Anda1; Lien, Ren-Chieh1

Published Dec 17, 2025 on Dryad. https://doi.org/10.5061/dryad.70rxwdcc9

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Dec 17, 2025 version files 7.67 MB

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Abstract

We present a method to quantify total, horizontal kinetic and available potential energies of linear internal waves (IW) and vortical mode (VM) using only two-dimensional (2D) (depth, along-track distance) measurements of horizontal velocity, such as those commonly taken by oceanic shipboard ADCP (SADCP). Previous IW and VM energy decomposition methods (Bühler et al. 2014, 2017, and their extensions) require both velocity and buoyancy measurements. Applying Helmholtz decomposition, 2D horizontal kinetic energy wavenumber (kx , kz) spectra are projected onto divergent Kdiv and rotational Krot components. IW total energy spectrum is EIW = 2Kdiv . VM total energy is EVM=1/Bu[(1+Bu)Krot-Kdiv], where Bu is Burger number with N and f buoyancy and inertial frequencies, kh horizontal wavenumber magnitude and kz vertical wavenumber. IW and VM horizontal kinetic energy (K) and available potential energy (P) can be inferred from EVM and EIW as functions of Bu. The proposed method, derived directly from IW and VM theoretical polarization relations, is demonstrated using two sets of velocity and density data. EVM derived by this new method agrees with results computed using the Bühler et al. (2014, 2017) method at Bu~O(1) and within a factor of ~ 2–3 elsewhere, confirming that IW and VM energy can be separated using only velocity data. At Bu ≪ O (0.1), EVM is dominated by PVM, with KVM/PVM=Bu, and using K alone to extract EVM through the proposed method is challenging due to inherent uncertainty in spectral measurements. This method could be applied to global SADCP datasets to separate upper ocean IW and VM energy contributions in different dynamical regions at horizontal scales O (100m) – O (100km) and vertical scales O (10m) – O (100m).