The longest unmanned, remotely-controlled voyage yet undertaken in Australian waters was completed in 2010 by an ocean glider that had spent 149 days measuring the properties of seawater in the Coral Sea.
Seagliders are autonomous vehicles designed to profile the water column in a zig-zag (down and up) pattern by changing their buoyancy. At each surfacing, they fix their position using GPS and transmit that and other data ashore via a communication satellite. If there is any need to alter the mission, for example straying off course due to unexpected currents, the onshore operator can command the glider to alter its trim on the next and subsequent dives.
The first Seaglider deployed in the Coral Sea is one small part of Australia's Integrated Marine Observing System (IMOS), which is an initiative of the Australian Government funded through the National Research Infrastructure Strategy (NCRIS). The glider was launched from an AIMS vessel near Townsville (19oS) and recovered five months later near Lizard Island (14oS). Its mission was controlled from the opposite side of the continent by operators at the IMOS National Facility for Ocean Gliders run by the University of Western Australia.
The Coral Sea is one of the most sparsely sampled marine environments in the world, leaving a significant gap in data and knowledge. Between launch and recovery, the Seaglider travelled 2,977 kilometres and made 768 dives to depths of one kilometre measuring key ocean variables such as temperature, salinity, plankton productivity, water turbidity and dissolved oxygen. This one glider mission has produced more data from this region than all previous research surveys put together, and at very much lower cost per observation.
The data gathered by sustained observing of the Coral Sea using multiple gliders will answer practical questions such as how ocean variability affects Australia's climate and marine ecosystems. For example, Queensland's recent summer of extreme events (floods and cyclones) was clearly connected with the strong La Nina of 2010-11 (see next highlight). In addition to rainfall and storminess, variations in heat transport from the Pacific Ocean are likely to drive the risk of mass coral bleaching on the Great Barrier Reef.