The situation is likely to change with the introduction of
the Argo float programme. Argo floats are drifting platforms
for the measurement of temperature and salinity as functions
of depth over periods of years (Roemmich et al., 2004). They
can be programmed individually for specific tasks; but a typical
Argo float follows one of two operational modes. In the
simple mode, the float drifts at a certain depth, often 2000 m,
rises to the surface every 10 days to take a temperature and
salinity profile from that depth, stays at the surface for up
to 12 h to transmit the data via satellite, and returns to its
deep drifting depth. In the park and profile mode, the float is
parked at a certain depth (the Argo operations centre recommends
1000 m), descends to 2000mevery 10 days to start the
temperature and salinity profile, comes to the surface, transmits
its data and returns to its parking depth. In the beginning
of 2006, 46% of floats profile to around 2000m and 66% profile
to depths greater than 1500 m.