General information:   https://ifg.tugraz.at/downloads/ocean-tides
Format description at: https://ftp.tugraz.at/outgoing/ITSG/oceanAndAtmosphericTides/README.pdf

Andersen, Ole Baltazar (2023). DTU23  Global Ocean Tide model (DTU23_OceanTide).
Technical University of Denmark. Dataset. https://doi.org/10.11583/DTU.23828874.v1

Converted into spherical harmonics by Torsten Mayer-Guerr