Ocean Tides

Ocean tides are the periodic rise and fall of sea level caused primarily by the gravitational attraction of the Moon and the Sun, combined with the Earth’s rotation. They result in large-scale redistribution of ocean water masses over daily and longer time scales.

In geodesy, ocean tides are a major source of temporal mass variability that affects the Earth’s gravity field, surface deformation (ocean tidal loading), and Earth rotation. Accurate tidal models are essential for correcting space-geodetic observations such as GNSS, VLBI, SLR, and satellite gravimetry, ensuring precise positioning, reference frame realization, and sea level monitoring.