APEX, like its predecessor ALACE, is an autonomous drifting profiler used to measure subsurface currents and make profile measurements. It surfaces at programmed intervals for data telemetry and geo-location via ARGOS satellite. Standard sensors include TP and Salinity; other sensor options are available.
APEX has a nominal 4-year life (though at least one has lasted more than seven years) and is designed to surface approximately 150 times from a maximum depth of 2000 meters. APEX is field proven. As of March, 2010, 6000 APEX floats have been delivered to users in 19 nations. Recent field data are available from the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean, Japan, Red, and South China Seas
APEX automatically adjusts buoyancy to follow an isobaric surface while drifting, or can be programmed to follow an isopycnal surface.
The optional "park and profile" feature, in use since March 2000, allows drift depth to be de-coupled from maximum profile depth. For example, a float might be programmed to drift at 1000 db, then descend to 2000 db before profiling upward to the surface.
Floats are provided deployment-ready, and are routinely deployed from merchant ships (VOS) while moving at 20+ knots. Proven VOS deployment packages are available options. APEX can be easily tested and re-programmed by connecting a terminal.