2026 GO-SHIP P04E
Reoccupying the P04E Tropical North Pacific Hydrographic Line
A Pacific Ocean hydrographic transect along ~9.5°N from Costa Rica to the Marshall Islands, deploying GO-BGC and Argo floats while collecting chemical, physical, and biological data to advance global Ocean climate research.
The U.S. Global Ocean Ship-based Hydrographic Investigations Program (U.S. GO-SHIP) is part of the international GO-SHIP program, which carries out a systematic and global re-occupation of select hydrographic sections.
The specific goals of this cruise are as follows:
- Re-occupation of the historic stations in this line. Roughly 156 stations, sampling water from a CTD rosette from near the surface to just off the seafloor
- A second cast dedicated to biological measurements at select stations throughout the line
- Deployment of 10 GO-BGC biogeochemical floats that measure properties like chlorophyll, nitrate, and oxygen in addition to temperature and salinity
- Deployment of 14 additional floats, including 6 core Argo and 8 deep Argo
Stations are spaced at 30 nautical miles (closer at boundaries and over bathymetric features), with one deployment per station of a CTDO/rosette system with 36 10-liter bottles and LADCP. The ship’s standard underway systems (including meteorology, surface seawater T/S/O2/pCO2/etc., centerline depth to bottom, navigation, hull-mounted ADCP, etc.) are also used. Program water column measurements include CTDO, salinity, oxygen, nutrients, CFCs, ocean carbon parameters, and various tracers.
Please join along on the journey by following the expedition blog!
Dates: May 9 – July 2, 2026
Ports: Majuro, Marshall Islands to Panama City, Panama
Chief Scientist: Andrew Babbin (MIT)
Co-Chief Scientist: Rolf Sonnerup (UW)
Ship: R/V Marcus G. Langeth (LDEO)
Track with station positions for the 1989 occupation of P04 occupied in three legs (P04W, P04C, and P04E) from west to east. The 2026 occupation of P04E will run from east to west and plans include positions extending to the easternmost station of P04W occupied by our Japanese colleagues in the spring of 2025.
2026 GO-SHIP P04E Tropical Pacific Expedition Logs
Floats Loaded
Ten BGC floats — eight adopted by classrooms — are checked out, decorated, and secured aboard R/V Langseth ahead of the P04E expedition.The R/V Marcus G. Langseth is in San Diego and the preparation for P04E is underway. Many groups are in town to load their gear onto...