WOA23 Decav Sound Velocity Datasets (Annual, Seasonal and Monthly) 1 degree resolution

This dataset contains derived climatological seawater sound-speed fields based on the World Ocean Atlas 2023 (WOA23), produced by NOAA NCEI from oceanographic observations assembled in the World Ocean Database 2023. WOA23 provides objectively analysed climatological fields at standard ocean depths. The decav reference spans 1955–2022 and averages seven period climatologies: 1955–1964, 1965–1974, 1975–1984, 1985–1994, 1995–2004, 2005–2014 and 2015–2022; it is not a pooled average of all observations. Resolution code 01 denotes a 1° latitude × 1° longitude grid, equivalent to 60 angular minutes in each direction. Temporal identifiers distinguish annual climatology (00); monthly climatologies (01 January, 02 February, 03 March, 04 April, 05 May, 06 June, 07 July, 08 August, 09 September, 10 October, 11 November and 12 December); and seasonal climatologies (13 January–March, 14 April–June, 15 July–September and 16 October–December). Seasonal names follow Northern Hemisphere winter, spring, summer and autumn. Annual and seasonal source temperature and salinity products contain 102 standard depth levels from 0 to 5500 m; monthly products contain 57 levels from 0 to 1500 m. Valid ocean coverage at individual depths depends on the source masks and local water depth. Sound-speed fields for the WOA23 decav, resolution 01 collection were derived using the Python CalculateSvp class from the objectively analysed temperature ( t_an ) and salinity ( s_an ) fields at the selected source grid cells and standard depths. Two separate estimates are produced: v_an_chen , calculated using the implemented Chen–Millero/UNESCO-type temperature–salinity–pressure polynomial, and v_an_leroy , calculated using the Leroy, Robinson and Goldsmith (2008) temperature–salinity–depth–latitude equation; both yield sound speed in metres per second. For the former, pressure is estimated from depth and latitude using Leroy and Parthiot (1998), with an optional configured regional correction, and converted from MPa to bar before evaluation. The class applies these calculations directly to the climatological inputs without additional spatial or vertical interpolation, extrapolation or missing-value filling. The results are derived climatological sound-speed estimates rather than direct acoustic measurements. The files in this dataset are used with these MB-System tools: mbsvpbest, mbsvproute, mbsvplocation, and mbsvpnearest. They are available here: https://github.com/dwcaress/MB-System References: https://www.ncei.noaa.gov/sites/default/files/2022-06/woa18documentation.pdf https://www.ncei.noaa.gov/access/world-ocean-atlas-2018/ https://www.ncei.noaa.gov/access/world-ocean-atlas-2023/