Reabsorption of lee-wave energy in bottom-intensified currents

Wu, Y., Kunze, E., Tandon, A., & Mahadevan, A, 2022. Reabsorption of lee-wave energy in bottom-intensified currents. Journal of Physical Oceanography. https://doi.org/10.1175/jpo-d-22-0058.1

While lee-wave generation has been argued to be a major sink for the 1-TW wind work on the ocean’s circulation, microstructure measurements in the Antarctic Circumpolar Currents find dissipation rates as much as an order of magnitude weaker than linear lee-wave generation predictions in bottom-intensified currents. Wave action conservation suggests that a substantial fraction of lee-wave generation can be reabsorbed into bottom-intensified flows. Numerical simulations are conducted here to investigate generation, reabsorption, and dissipation of internal lee waves in a bottom-intensified, laterally confined jet that resembles a localized abyssal current over bottom topography. Reynolds-decomposed energy conservation is consistent with linear wave action conservation predictions that only O(0.1) of lee-wave generation is dissipated, with the bulk of lee-wave energy-flux reabsorbed by the bottom-intensified flow. Thus, water column reabsorption needs to be taken into account as a possible mechanism for reducing the lee-wave dissipative sink for balanced circulation.