Seawater sound velocity model dataset for full-ocean-depth EM124 mapping of the Challenger Deep by R/V Hakuho-maru

This dataset contains five seawater sound-velocity profiles prepared for full-ocean-depth multibeam processing in the Challenger Deep. They comprise an upper-ocean XCTD profile acquired by R/V Hakuho-maru during cruise KH-23-9 on 30 November 2023 and extended to 12,000 m using climatological values; a full-depth profile derived from KH-92-1 CTD observations; a composite profile combining the KH-23-9 XCTD data from 0 to 1,915 m with the KH-92-1 CTD data below 1,915 m; and two independent full-depth profiles based on 2020 DSV Limiting Factor and 2016 R/V Sonne CTD observations. Sound velocity was calculated using the Del Grosso equation for four profiles and TEOS-10 for the DSV Limiting Factor profile. The files are provided as one Kongsberg ASVP file and four SVP_VERSION_2 ASCII files, each containing depth (m), sound speed (m/s), and format-specific header and provenance information. The dataset supports reproduction and comparison of sound-velocity corrections applied to full-ocean-depth Kongsberg EM124 soundings.