2025 GO-SHIP I09N

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 I09N line crosses the Indian Ocean and was previously sampled in 1995, 2007, and 2016. After first filling a gap left by the 2024 I08S occupation, I09N will extend northward along the 95°E meridian into the Bay of Bengal to 18°N.

The specific goals of this cruise are as follows:

1. Re-occupation of the historic stations in this line. Roughly 122 stations, sampling water from a CTD rosette from near the surface to just off the seafloor
2. A second cast dedicated to biological measurements at select stations throughout the line
3. Deployment of 10 GO-BGC biogeochemical floats that measure properties like chlorophyll, nitrate, and oxygen in addition to temperature and salinity
4. Deployment of 10 core Argo floats
5. Deployment of 10 drifters in support of NOAA’s Global Drifter Program

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!

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