The World Ocean Atlas 2018: Improvements and Uses of Climatological Mean Fields

The release of the World Ocean Atlas 2018 continues the periodic release and improvement of climatological mean fields of ocean variables at standard depths in the ocean from the surface to 5,500 m depth started in 1982. The consistency of the basic method of calculation of the mean fields of temperature, salinity, dissolved oxygen, and nutrients, allows for continuity in general uses of the climatological mean fields. Improvements in the calculation methods, such as refinements in the temperature and salinity fields based on a stable water column, enhance the utility of the fields. Of course, the addition of more data, both recent and historical, allows for the addition of time period (decadal) specific climatological means, including a climate norm 1981-2010 period for temperature and salinity. The uses of the climatological mean fields range from baselines for tracking changes to ocean variables, initialization and boundary conditions for models, quality control for new and existing measurements, and general education on the large-scale features of the oceans. Comparisons with previous iterations of the World Ocean Atlas and other global climatological mean fields show improvements and a convergence of knowledge about the general features of oceanographic variables.