Dissolved methane (CH4) and nitrous oxide (N2O) from ships underway seawater supply and CTD Niskin samples during AMT27 (DY084) between the 7th October and 3rd November 2017.

This dataset contains dissolved concentrations of nitrous oxide and methane along a transect between the UK and the Falkland Islands during the boreal autumn of 2017 during the RRS Discovery research cruise DY084 (AMT27). Data were collected between the 7th of October 2017 and the 3rd of November 2017 (A methodological problem meant that data is not available for the first 13 days of the cruise). Seawater was collected from the ship's underway seawater supply into 0.5L borosilicate flasks, as well as from Niskin bottles deployed on a stainless CTD frame. CTD samples were collected using acid cleaned Tygon tubing directly from CTD Niskin into 0.5L borosilicate flasks. Samples were overfilled in order to expel air bubbles, poisoned with 200µL of saturated HgCl2 solution and temperature equilibrated at 25.0 ± 0.5°C. In all cases samples were analysed within 8 hours of collection. N2O and CH4 were determined by single‐phase equilibration gas chromatography with electron capture detection and flame ionisation detector respectively.