What does a float do?

Argo floats are programmed to descend to a depth of typically 1500 to 2000 metres and drift at this depth for nine days before rising to the surface.  During the ascent a temperature and salinity profile is measured. These data are then transmitted via satellite (currently Argos) before the float starts another cycle. A schematic of a simple float mission is given below.

Argo floats are expected to be capable of measuring as many as 150 profiles during their lifetime and operate for four to five years. Each float (including its antenna) is typically 2 to 2¼ m long and up to 30 kg in weight. Currently floats from three commercial manufacturers are used within Argo Germany  — Teledyne Webb Research, Optimare and NKE.