Tidal dissipation in the early Eocene and implications for ocean mixing

The tidally driven vertical diffusivity in the abyssal ocean during the early Eocene (55Ma) is investigated using an established tidal model. A weak tide is predicted in the Eocene ocean, except in the Pacific. Consequently, the integrated global tidal dissipation rate is a mere 1.44TW, of which 40% dissipate in the Pacific. However, due to a stronger abyssal vertical stratification the predicted Eocene vertical diffusivities are consistently larger than at present. The results support the hypothesis that altered tidal dissipation may play a role in explaining the maintenance of past climate regimes, especially the anomalously warm temperatures in the southwest Pacific in the Eocene, and the low dissipation rates may be important for lunar evolution history.