Semi‐diurnal and diurnal tidal dissipation from TOPEX/Poseidon altimetry

TLDR

Tidal energy dissipation for eight semi‑diurnal and diurnal constituents is estimated via a global inverse solution constrained by TOPEX/Poseidon altimetry, and the absence of free internal waves poleward of 30° at diurnal frequencies likely limits baroclinic conversion as an energy sink for barotropic diurnal tides. The semi‑diurnal constituents exhibit similar spatial patterns with roughly one‑third of total dissipation occurring in the deep ocean over rough topography, while diurnal constituents differ markedly, with only about 10% of dissipation in the deep ocean, a contrast largely attributable to their distinct spatial patterns of tidal currents.

Abstract

Tidal energy dissipation is estimated for eight semi‐diurnal and diurnal constituents using a global inverse solution constrained by TOPEX/Poseidon altimeter data. Very similar spatial patterns are obtained for all semi‐diurnal constituents, with about one third of the total dissipation occurring in the deep ocean over rough topography. Maps for diurnal constituents are also similar amongst themselves, but quite different from the semi‐diurnal results. For diurnals a smaller fraction of dissipation, roughly 10%, occurs in the deep ocean. Much of the difference can be explained by the very different spatial pattern of diurnal and semi‐diurnal tidal currents. The lack of free internal waves at frequencies poleward of 30° at diurnal frequencies also probably plays a role, limiting the effectiveness of baroclinic conversion as an energy sink for barotropic diurnal tides.