| Domain | Oceanic | Description | Oceanic measurements of sub-surface ocean velocity provide the data needed for estimates of ocean transports of mass, heat, freshwater and other properties on basin to global scales. While the vertical shear of the component of horizontal velocity perpendicular to each station pair of a hydrographic section is straightforward to calculate from geostrophy, determining the absolute velocity field to sufficient accuracy for transport estimates is more problematic. Full-depth direct sub-surface ocean velocity observations can resolve complex velocity structure in the major boundary currents and at the ocean sea floor, and near the equator where synoptic geostrophic calculations are useless. Direct velocity observations are essential for resolving the Ekman-layer contribution to property transports, determining large-scale gyre circulations, estimating ocean mass, heat, freshwater and carbon transports, and providing direct estimates of boundary current transports. Velocity estimates can be used in data assimilation. [GCOS-195 5.4.3] |