The Ocean Gliders facility operates a fleet of autonomous underwater ocean gliders that undertake measurements from shelf and boundary currents in Australian waters. As traditional ship-based oceanographic observations are expensive and time consuming, the development of autonomous ocean gliders to sample the marine environment represents a technological revolution for oceanography. The gliders are relatively cheap, reusable and can be remotely controlled, making them a relatively cost-effective method for collecting repeat subsurface ocean observations. They also allow for the acquisition of data under inclement weather conditions. Equipped with a variety of sensors, the gliders are designed to deliver ocean profile data. Furthermore, the unique design of the gliders enables them to move horizontally through the water while collecting vertical profiles. The use of these contemporary gliders provides a unique opportunity to effectively measure the boundary currents off Australia, which are the main link between open-ocean and coastal processes. The Ocean Gliders facility operates a number of gliders with target regions including the Coral Sea, East Australian Current off New South Wales and Tasmania, Southern Ocean southwest of Tasmania, the Leeuwin and Capes Currents off South Western Australia and the Pilbara and Kimberly regions off North Western Australia.
Instrumentation and Data
Ocean gliders propel themselves through changes in buoyancy. By alternately reducing and expanding their volume, gliders can descend and ascend through the ocean using very little energy. Unlike other automated ocean sampling equipment, such as Argo floats, gliders have wings, a rudder and a movable internal battery pack allowing them to move horizontally in a selected direction while sampling. Essentially this means that the gliders’ horizontal position is controllable, allowing researchers to determine where the glider goes and permitting precise sampling of particular oceanographic features and profiling across strong currents. Being unmanned and fully-submersed, the ocean gliders can work around the clock in all weather conditions continuously sampling the water for temperature, salinity, dissolved oxygen, chlorophyll and turbidity. They are remotely controlled and navigate by waypoints, fixing their position via the Global Positioning System (GPS) through Iridium satellite. Each time the glider surfaces, collected data and new waypoints can be relayed via satellite. Two types of gliders are used as part of the IMOS Ocean Gliders facility; Slocum gliders and Seagliders. Slocum gliders are used in intensive coastal monitoring and Seagliders are used to gather long-term environmental records. Both gliders collect high resolution profiles of physical, chemical, and bio-optical variables.