Secular Changes of Ocean Tides – Processes and Projections

• Applicants: Professor Dr. Michael Schindelegger; Professor Dr. Athanasios Vafeidis, since 11/2023
• Subject Area: Oceanography
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 451039647

Secular changes of tides are among the most puzzling signals in the world ocean. To elucidate the causative mechanisms of these changes and reliably constrain future tidal evolution, we lay out a comprehensive modeling framework that incorporates trends of relative sea level, ocean stratification, and Antarctic ice-shelf geometries in multi-constituent tidal simulations on both global and regional scales. The response to the proposed forcing mechanisms is first worked out from ~1970 to 2015, using prior global barotropic (2D) integrations and regionally nested baroclinic (3D) runs in the rapidly warming Northeast Atlantic and the seas of Australia. We assess the skill of this machinery through comparisons of modeled trends in constituents and tidal levels with observations, the latter being cleaned from anomalies of local origin and reduced to the large-scale patterns of interest. The modeling scheme – augmented by large baroclinic sensitivity tests for global stratification effects on ocean tides – is subsequently used to carry out tidal projections to the year 2100 along high-end emission paths. We implement future climate conditions across the triplet of forcing factors through physical modeling and downscaling techniques, and complement end-of-century estimates in the two target regions by explicitly modeled uncertainties. As such, the project paves the way toward proper quantification of sustained tidal variability, aiding branches of science and application in which tides are considered critical elements.

• DFG Programme: Research Grants
• Ehemaliger Antragsteller: Professor Dr.-Ing. Arne Arns, until 11/2023