WOA23 B5C2 Sound Velocity Datasets (Annual, Seasonal and Monthly) 1 degree resolution

This dataset contains derived climatological seawater sound-speed fields based on temperature and salinity from the World Ocean Atlas 2023 (WOA23), produced by NOAA NCEI using observations assembled in the World Ocean Database 2023. WOA23 supplies objectively analysed climatological oceanographic fields on standard depth levels. Period code B5C2 identifies 2015–2022, an eight-year climatological interval rather than the full 1955–2022 decadal average. Resolution code 01 specifies 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). The seasonal names winter, spring, summer and autumn refer to the Northern Hemisphere. Annual and seasonal source temperature and salinity fields contain 102 standard depth levels from 0 to 5500 m, while monthly fields contain 57 levels from 0 to 1500 m. These are nominal grid depths; individual ocean profiles may have shallower valid coverage because of source masking and bathymetry. Sound-speed fields for the WOA23 B5C2 , 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/