WHAT IT MEASURES

• Temperature, salinity, and pressure from the standard Argo array.

• Biogeochemistry data including pH, nitrate, chlorophyll, suspended particles, and dissolved oxygen.

• Two of the eight floats onboard The World were fitted with dissolved oxygen sensors.

• These measurements help reveal both physical ocean conditions and the chemistry of marine ecosystems.

HOW IT WORKS

• Each float is buoyancy-driven and changes depth by shifting about 240 cc of mineral oil between an internal pressure housing and an external rubber bladder.

• Floats are typically parked at 1,000 m depth between profiles, where low light reduces biological growth and helps preserve accurate ballasting.

• Every 10 days, the float descends to 2,000 m and then profiles upward to the surface, collecting data through the water column.

• At the surface, it raises its antenna, transmits data via the Iridium satellite network, and then returns to 1,000 m for the next cycle.

• Floats are battery-powered and usually operate for 8–10 years.

INTERESTING FACTS

• Even in strong equatorial currents, floats usually drift only one to two degrees over their lifetime.

• Ice-covered deployments can use an ice-avoidance algorithm to prevent surfacing under sea ice.

• If conditions suggest ice is present, the float stores data internally and waits for ice-free conditions before transmitting.

• Some floats can retain multiple years of data before surfacing again.

• Argo is one of the most important long-term ocean observing systems in the world, because it provides repeated measurements from remote parts of the ocean.