The Pacific Ocean S04P repeat hydrographic line was reoccupied for the US Global Ocean Carbon and Repeat Hydrography Program. Reoccupation of the S04P transect occurred on the RVIB Nathaniel B Palmer from March 9, 2018 to May 14, 2018. The survey of S04P 2018 consisted of CTDO, rosette, LADCP, UVP, water samples and underway measurements. The ship departed from the port of Hobart on the island of Tasmania, Australia and completed the cruise in the port of Punta Arenas, Chile.

A total of 122 stations were occupied with one CTDO/rosette/LADCP/UVP package. 122 stations and 125 CTDO/rosette/LADCP/UVP casts including 2 test casts were performed. The stations were, for the most part, a reoccupation of S04P cruise from 2011. 18 floats were deployed: 6 SOCCOM, 5 FSU, 5 CSIRO, and 2 EM-APEX. 20 drifters were deployed. CTDO data and water samples were collected on each CTDO, rosette, LADCP, and UVP cast, usually within 10 meters of the bottom. Water samples were measured on board for salinity, dissolved oxygen, nutrients, DIC, pH, total alkalinity and CFCs/SF6. Additional water samples were collected and stored for shore analyses of 𝛿15N and 𝛿18N, 𝛿18O, DOC/TDN, 13C/14C, POC, HPLC, rare earth elements, Neodymium, and noble gases.

A sea-going science team assembled from 20 different institutions participated in the collection and analysis of this data set.

Carbon Data
CTD and other hydrographic data
Section designation: S04P
Chief Scientists: Alison Macdonald and Ellen Briggs
Dates: 9 Mar 2018 to 14 May 2018
Ship: RVIB Nathaniel B. Palmer
Ports of call: Hobart, Australia to Punta Arenas Chile
Stations: 122
Geographic boundaries 75.2905°S to 59.6176° S by 159.1537° E to 73.499° W