CTD profiles collected near 16S in the tropical South Atlantic Ocean west, east, and over the Mid-Atlantic Ridge on cruise JC275 (February-March 2025).

This dataset contains CTD profiles from cruise JC275, collected near 16S in the tropical South Atlantic Ocean west, east, and over the Mid-Atlantic Ridge. The data were collected from 25th February to 26th March 2025. Most profiles were shallow (upper 250-300 m) to sample the deep chlorophyll maximum. Other profiles were ~500-1000 m deep and were designed to observe the water masses and nutrient distributions in the pycnocline. A few profiles were full-depth and were designed to measure the sound speed profile for calibrating acoustic instruments and to observe the full-depth water mass structure for regional context. Calibrations for salinity, dissolved oxygen, and chlorophyll concentration were applied based respectively on salinometer, laboratory titration, and laboratory total chlorophyll analyses from water samples collected with Niskin bottles. The data was processed using the mexec/mstar software package, and manual editing of outliers was performed where necessary. Data is provided in the standard binned 2 dbar format, as well as binned in 0.5 dbar bins for better resolving small-scale features that were a focus of the field program, such as the deep chlorophyll maximum. The data were collected as part of the NERC Discovery Science project 'Enhanced carbon export driven by internal tides over the mid-Atlantic ridge' (CarTRidge) (grant ref NE/X013758/1).