Three ~50m vertical profiles of the dissolved O2/Ar ion current ratio in seawater with depth, measured at high vertical resolution using Membrane Inlet Mass Spectrometry. 2017.

Seawater was sampled via tubing with depth between the surface and ~50m, then measured for the ion current ratio of dissolved O2/Ar using Membrane Inlet Mass Spectrometry (Tortell, 2005; Kaiser et al., 2005). Measurements were conducted during the P1706 CCE-CalCOFI Process Cruise (1 Jun - 2 Jul 2017). Profiles were taken on 11 June, 15 June, and 25 June during Cycle 1, Cycle 2, and Cycle 4, respectively. Oxygen saturation and solubility were separately and concurrently measured from sampled seawater using an Aanderaa optode oxygen sensor. The ratio of seawater O2/Ar to the O2/Ar ratio at equlibration with the atmosphere is also reported. Vertical profiles of O2/Ar are used to correct surface measurements of productivity using O2/Ar for vertical influences, and can also be used to qualitatively assess profiles of community metabolic activity with depth.