This event log was recorded during R/V Roger Revelle cruise RR2311 in the Eastern Tropical South Pacific, off the coast of Chile and Peru, during November and December 2023. The cruise track included five process stations, three of which were designated oxygen-deficient zone (ODZ) stations (contained a relatively thick interval of oxygen-depleted water, PS1, PS2, PS3) and two of which were outside the strong oxygen minimum zone (PS4, PS5). Experimental manipulations to measure nitrogen (N) cycle processes were carried out at these stations. The sampling strategy was tailored to the process under investigation, e.g., photosynthesis in surface waters, denitrification in oxygen depleted layers. Complete depth profiles were measured for a few processes (nitrification) but most experiments targeted a few critical features (e.g., oxycline, core of the ODZ).

Nine transect stations were included at approximately evenly spaced intervals between the process stations and the end point of the cruise in Arica, Chile. Depth profiles of dissolved inorganic nitrogen nutrients and nitrous oxide were measured at the transect stations.