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Abstract:
The evolution of paleo tides has important implications for several branches of geoscientific research. For example, the presumably boosted generation of internal tides under glacial conditions is linked to increased tidal mixing, the intensity of the overturning circulation (e.g., Wilmes et al., 2019), and thus paleoclimate. Another application is the interpretation of Sea Level Index Points, influenced by the dynamic tidal levels, for reconstructing paleo sea level. A curious aspect, first predicted by Griffiths et al. (2008), is the emergence of a megatidal regime in the Arctic, with possible links to Heinrich Events (e.g., Velay-Vitow et al. 2020). While several studies reproduced the phenomenon, its extent, and sensitivity could be better constrained. Many ocean tide models operate with open boundary conditions in the Arctic, for which reason they suppress the free formation of the described tidal regime. Thus, it must be determined if this localized Arctic phenomenon induces significant feedback on tidal dynamics in the North Atlantic.
This contribution focuses on the emergence and robustness of the ‘Arctic Megatide’. We present sensitivity experiments performed with a truly-global, data-unconstrained ocean tide model. The simulations establish the reproducibility of the phenomenon but predict high sensitivity to the representation of Self-Attraction and Loading (SAL), along with paleo bathymetric features. The ensemble is augmented with hybrid simulations, where the Arctic bathymetry is kept at a non-resonant state. The model differences indicate that the Arctic mega tide increases tidal mixing in the North Atlantic by 20%, with possible implications for ocean circulation.
