Dr Phil Sutton of NIWA outlines the aims of the international Argo and Jason projects. Argo uses over 3,000 scientific floats to continuously measure the salinity and temperature of the ocean. Jason uses satellites to monitor sea surface height.
Updates: Argo is addressing technological challenges to keep the floats operating in harsh marine environments. Battery performance now lasts up to 6 years or longer. Sensors, ice deterctors and high speed communication have helped Argo improve and expand its coverage. The majority of floats in the Argo array now use the Global Positioning System (GPS) to establish float positions and use Iridium LEO satellites to transmit their data.
Transcript
Dr Phil Sutton
Argo is an international programme to deploy the profiling floats in all of the world’s oceans. The aim of the programme was to have 3,000 floats in the water. That number was chosen to give adequate coverage so that you weren't missing any signals in the world’s oceans. Twenty-seven different countries have bought floats and deployed floats, but all of the data are freely available to anybody who wants to download them from the internet.
For the first time we've got almost real time measurements of what the oceans doing everywhere. Historically the way you collected information about in the ocean was you took a ship out, and you made measurements in a specific location, at a specific time, and often along a defined section or transect. That wouldn't necessarily give you much information about what was happening even a few hundred kilometres away, or happening at a slightly different time. Taking a ship out is very good because you get to choose exactly where you collect your data, but it’s very very expensive and, of course, there are only so many ships, whereas having 3,000 Argo floats dotted all round the worlds oceans, means that for the first time ever we can actually know what the ocean is doing at any given moment.
Now, one of the challenges of Argo is, if you are going to maintain 3,000 floats in all the world's oceans, the floats have about a 5-year life on average – well, that is their design life. They are getting close to that now. So that means, of course, you've got to deploy 600 floats a year just to maintain the network. So as long as you want Argo to continue, you are going to be continually deploying floats. The are trying to engineer the floats to last a little bit longer for obvious reasons, and progress is being made there.
Jason is a system of satellite altimeters, and they are going around measuring the height of the sea surface, and they can do that to a resolution of a few centimetres. So what the height of the sea surface tells you is really a measure of the density of the ocean all the way through the water column. If you are in a part of the ocean that is warmer and fresher – so less dense – the surface of the ocean stands slightly higher.
Acknowledgements
Argo data in this video clip was collected and made freely available by the International Argo Project and the national programmes that contribute to it. (www.argo.ucsd.edu, www.ocean-ops.org). Argo is a pilot programme of the Global Ocean Observing System.
NIWA
Scripps Institution of Oceanography, UCSD
Southampton Oceanography Centre, UK
