Oceans play a key role in the global climate system by storing and transporting heat and freshwater over thousands of kilometres. The heat capacity of the top three metres of the ocean is equivalent to that of all of the atmosphere, so changes About half the floats in the in ocean heat content and freshwater fluxes play a large role in Australian region are provided by climate change and variability. Historically, a lack of sustained, IMOS and partners. high resolution observations of the atmosphere and oceans has Argo Australia is the third largest hindered our ability to forecast climate and ocean conditions. contributor of active floats to the Argo floats provide global measurements of temperature, salinity array (after the USA and Japan). Argo has made available over and currents in the upper 2,000 metres of the ocean. Argo data 53,000 deep ocean profiles has revolutionised our ability to examine global scale ocean around Australia (over 17,000 from circulation and air-sea interactions, and to improve climate models IMOS floats), and over 500,000 and predictions. Argo Australia is the Australian contribution to the globally. Data is available within ARGO international Argo program. 24 hours as part of the real-time data stream and highly quality- controlled data is available after 6 months, as part of the delayed- mode data stream. Argo data now comprises the single largest source of in situ ocean data and, in quantity, has exceeded all historical winter data available for the Southern Hemisphere. Applications of Argo data International Argo provides data from the global oceans. From Australia’s perspective, this means that both regional and remote impacts on our climate Figure 1. Schematic of the life cycle of an Argo float. How an Argo float works float density and allows it to cycle Argo floats are autonomous vertically through the water. Argo instruments that are deployed from floats have a lifetime of about ships to measure water properties 5 years, although some have between a depth of 2,000 m and surpassed 7 years. Floats can the sea surface every ten days operate under harsh conditions and transmit data via satellite. and in remote areas, such as the After deployment, an Argo float Southern Ocean, which are difficult sinks to 1,000 m depth, drifts to monitor using conventional with the current for 9 days, sinks platforms. to 2,000 m and then rises to the Argo data surface continuously measuring temperature and salinity. Buoyancy Argo Australia and international is controlled by an onboard partners have established an computer that pumps oil in and extensive array of floats around out of an external bladder, altering Australia - from the dateline to the Figure 2. Argo float coverage in the Australian the float volume while maintaining middle of the Indian Ocean and region in January 2009 (green dots) superimposed constant mass. This changes the from the equator to Antarctica. on a satellite Sea Surface Temperature map. can be studied. Satellite altimeters papers using Argo data currently to deploying 50 floats a year reveal the shape of the ocean published each year. in the Australasian region, and surface and together with Argo Argo provides insight into to enhancing coverage in the data provide the ability to monitor broadscale ocean variability; Southern Hemisphere. global ocean circulation and sea essential context for IMOS Iridium communications are level rise. Real-time Argo data observations closer to the coast, allowing faster data transfer, also supports seasonal climate such as by Gliders and Radar. higher resolution profiles and prediction systems, e.g. seasonal 1 two-way communication. An climate forecasting (POAMA ) Looking to the future extension of the core mission to and daily ocean forecasting 2 Sustaining Argo into the future is the high latitudes (beyond 60˚S (BLUElink ). a priority and a major challenge. and 60˚N) would ensure that Argo w . i m o s r g a u IMOS Argo and Ships of A global 3 x 3 degree network becomes a truly global array. Opportunity (SOOP) Facilities requires 3,300 floats between Beyond measuring temperature provide complementary data. 60˚S and 60˚N. The array has and salinity, additional sensors High density SOOP transects reached its target density only at on floats are making new are designed to measure ocean mid-latitudes and in the northern physical, chemical and biological transports and currents, while Argo hemisphere. There is a shortfall measurements. monitors large scale ocean heat of more than 500 floats in the and freshwater fluxes. Information southern hemisphere. Continued International links commitment from the international from Argo is used in global change The success of Argo as a community is required to reach research and in assessment and global program is due to strong the target density and maintain management of fisheries and international support with 24 the global array over the longer ecosystems. Argo data underpins nations deploying instruments. term. IMOS, through its support marine and climate research with Internationally, Argo is sponsored of Argo Australia, has committed over 100 peer reviewed scientific by the World Climate Research 0 Programme’s Climate Variability 100 ) and Predictability project 200 (CLIVAR) and the Global Ocean 300 Depth (m 400 Data Assimilation Experiment 500 (GODAE). It is a pilot project of the 2003 2004 2005 2006 2007 2008 2009 Time (years) Global Ocean Observing System ºC (GOOS). 5 10 15 20 25 30 0 Partners ) 100 • Antarctic Climate and 200 Ecosystems Cooperative 300 Depth (m Depth Research Centre 400 500 2003 2004 2005 2006 2007 2008 2009 • Bureau of Meteorology Time (years) • CSIRO Marine and 33 33.5 34 34.5 35 Atmospheric Research Figure 3. Example of a continuous data record from a long lived IMOS Argo • Royal Australian Navy float between Northwest Australia and Indonesia. The float is profiling through very warm fresh near surface layers in the early part of each year when the Northwest Monsoon is active. Achieving a 6 year lifetime for a float profiling to 2,000m in these conditions far outstrips the 3-4 year lifetime expected when Argo first began. More information Argo Australia http://imos.org.au/argo.html CSIRO Argo Australia operator http://www.cmar.csiro.au/argo International Argo http://www.argo.net 1 POAMA seasonal forecasting http://poama.bom.gov.au 2 BLUElink ocean forecasting http://www.bom.gov.au/bluelink IMOS is supported by the Australian Government through the National Collaborative Research Infrastructure Strategy and the Super Science Initiative..