A wave powered profiler for long term monitoring

Abstract

The collection of periodic profiles of oceanographic data at specific sites is a critical component of oceanographic monitoring programs. Typically, this type of work is completed by lowering instrumentation from ships but the cost of these operations has often meant that the temporal and spatial coverage of these surveys is less than ideal. As an alternative, moored profilers have been developed but the energy required to move a substantial package up and down a mooring wire can represent a major limitation. A simple, economical and autonomous device to accomplish the task of completing a large number of profiles in a moored or drifting configuration has been developed at the Bedford Institute of Oceanography. This system overcomes the limitation of previous self-contained profiling devices by deriving the power needed to move vertically in the water column from the energy of surface waves. A one way clamp provides the mechanism by which wave action acting on a surface float sends a buoyant instrument package down a mooring line. Once at the bottom and when a profile is desired, the clamp is released allowing the instrument to float to the surface. Some data from field trials as well a description of the principle of operation of the device are presented.