Friday, 24 March 2017

Recovering 007 and the temperature and salinity of the deep ocean

Two days ago the RRS James Cook recovered a novel profiling float.  As its serial number, 007, suggests very few of these have so far been deployed.  This one had not been working as it should and our colleagues were keen to get it back so that the problem could be diagnosed to improve the reliability of future versions.

Since 2000 oceanographers have been continuously monitoring the temperature and salinity of the upper 2000m of the worlds oceans using an array of free drifting Argo floats. Every 10 days these floats sink to a depth 1000m and drift at that depth for 9 days. On the 10th day they sink to 2000m and then return to the surface to transmit their data to a satellite. These floats can operate for up to 5 years and their data are made publicly available within hours of collection ( available here ).

Positions of the floats that have delivered data within the last 30 days  
The upper ocean has become well sampled with nearly 4000 floats delivering data. However, we know relatively little about how the temperature of the ocean below 2000m is changing.   Some pilot programs with deep profiling floats that can reach 4000m or 6000m depth have recently started and we hope that in the coming years they will be sampling the deep ocean across the world

Our colleagues at NOC are working on one pilot program and during an expedition in this region one year ago 4 deep Argo floats where deployed.    It is one of these that we recovered this week.    During this expedition we are deploying 6 more deep Argo floats from Scripps Institution of Oceanography in the USA.

Deep Argo float recovery
The Argo program is a collaborative partnership of more than 30 nations from all continents. The data from the program has revolutionised our capability to observe climatically important variations in the heat content of the ocean.

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