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. w w w . i m o s . o r g . a u

Antarctic Climate and Ecosystems Cooperative Research Centre Bureau of Meteorology CSIRO Marine and Atmospheric Research Australian Navy Royal Partners to deploying 50 floats a year 50 floats a year to deploying and Australasian region, in the in the to enhancing coverage Southern Hemisphere. are Iridium communications transfer, allowing faster data and higher resolution profiles An two-way communication. mission to extension of the core 60˚S the high latitudes (beyond Argo that and 60˚N) would ensure becomes a truly global array. Beyond measuring temperature additional sensors and salinity, on floats are making new physical, chemical and biological measurements. International links Argo as a The success of global program is due to strong international support with 24 nations deploying instruments. Argo is sponsored Internationally, Climate Research by the World Climate Variability Programme’s and Predictability project and the Global Ocean (CLIVAR) Experiment Assimilation Data (GODAE). It is a pilot project of the Global Ocean Observing System (GOOS). • • • • POAMA seasonal forecasting http://poama.bom.gov.au POAMA BLUElink ocean forecasting http://www.bom.gov.au/bluelink More information Australia http://imos.org.au/argo.html Argo Australia operator http://www.cmar.csiro.au/argo Argo CSIRO Argo http://www.argo.net International 1 2

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25 2008 2008 5 34. 2007 20 2007 and the Super Science Initiative. papers using Argo data currently Argo papers using each year. published into Argo provides insight variability; broadscale ocean IMOS essential context for to the coast, observations closer and Radar. such as by Gliders Looking to the future Looking to the is Argo into the future Sustaining challenge. a priority and a major x 3 degree network global 3 A requires 3,300 floats between The array has 60˚S and 60˚N. reached its target density only at mid-latitudes and in the northern shortfall There is a hemisphere. of more than 500 floats in the southern hemisphere. Continued commitment from the international community is required to reach the target density and maintain the global array over the longer term. IMOS, through its support Australia, has committed Argo of 2006 34 2006 ime (years) 15

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200 300 400 500 100

Depth (m Depth ºC ) 500 100 200 300 400

) Depth (m Depth Australian Government through the National Collaborative Research Infrastructure Strategy IMOS is supported by the float between Northwest Australia and Indonesia. The float is profiling through float between Northwest very warm fresh near surface layers in the early part of each year when the Achieving a 6 year lifetime for a float Northwest Monsoon is active. profiling to 2,000m in these conditions far outstrips the 3-4 year Figure 3. Example of a continuous data record from a long lived IMOS lifetime expected when Argo first began. lifetime expected when IMOS Argo and Ships of Argo and IMOS Opportunity (SOOP) Facilities provide complementary data. transects High density SOOP are designed to measure ocean Argo transports and currents, while monitors large scale ocean heat and freshwater fluxes. Information is used in global change Argo from research and in assessment and management of fisheries and Argo data underpins ecosystems. marine and climate research with over 100 peer reviewed scientific can be studied. Satellite altimeters Satellite altimeters can be studied. shape of the ocean reveal the Argo with surface and together to monitor data provide the ability and sea global ocean circulation data Argo level rise. Real-time climate also supports seasonal e.g. seasonal prediction systems, (POAMA climate forecasting and daily ocean forecasting and daily ocean forecasting (BLUElink