Seawater biogeochemical measurements (nutrients, chlorophyll-a and pCO2) from high-resolution underway sampling across the Agulhas Bank in 2014 and 2015

Underway water supply systems on modern research vessels allow for easy access to a continuous supply of near-surface seawater samples, that can be sampled inline and continuously, or discretely. Such sampling strategies are under-utilized and can provide data valuable for comparison with satellite observations of surface ocean properties, and investigation of sub-mesoscale variability and processes. This dataset represents two transects across the Agulhas Bank, a critical ocean area positioned at the southern tip of Africa, between the southern extremities of the Benguela and Agulhas Currents. On both transects discrete water sampling was carried out at 15 to 20-minute time intervals, while the ship was underway, for analysis of dissolved nutrients and chlorophyll-a; inline measurements for temperature, salinity and pCO2 were noted at each discrete water sampling point. The first transect was carried out on board the R/V SA Agulhas II in April 2014, and the second on board the R/V Algoa, in April 2015. The underway pCO2 data should be treated this caution, as the accuracy of the onboard calibration cannot be guaranteed; the data for pCO2 is included regardless, since the trends are potentially useful and interesting qualitatively.