A moored profiling instrument

The specifications and performance of a moored vertical profiling instrumen t, designed to acquire near-full-ocean-depth profile time series data at hi gh vertical resolution, are described. The 0.8-m-diameter by 0.4-m-wide dev ice utilizes a traction drive to propel itself along a standard mooring wir e at a speed of similar to 0.3 m s(-1). The average power required to profi le at this speed is 1-2 W; the present sensor suite and controller draw abo ut 1.5 W. Based on these figures, the instrument's battery capacity will su pport approximately 1 million meters of profiling. Instrument actions are r egulated by an onboard microcontroller, allowing complex dive programs to b e carried out. Oceanographic and engineering data are recorded internally o n a hard disk interfaced to the controller. The measurement suite thus far deployed includes a CTD for deriving ocean temperature and salinity profile s, and an acoustic current meter that returns ocean velocity profile data. Addition of other oceanographic sensors is anticipated. Results from severa l trial deployments in the open ocean are reported.