It was first produced in 1994[2] (based on the earlier Climatological Atlas of the World Ocean, 1982[3]), with later editions at roughly four year intervals in 1998, 2001, 2005, 2009, 2013, 2018, and 2023.
[1] The fields that make up the WOA dataset consist of objectively-analysed global grids at 1° spatial resolution.
The fields are three-dimensional, and data are typically interpolated onto 33 standardised vertical intervals[5] from the surface (0 m) to the abyssal seafloor (5500 m).
In terms of temporal resolution, averaged fields are produced for annual, seasonal and monthly time-scales.
Early editions of the WOA additionally included fields such as mixed layer depth and sea surface height.