AMT24

The twenty-fourth research cruise in the Atlantic Meridional Transect series, between the UK and the Falkland Islands, and funded by NERC National Capability, has been successfully completed. AMT24 set sail from Immingham on 22nd September aboard the British Antarctic Survey vessel James Clark Ross, and arrived in Stanley on 2nd November 2014.

The highlights of the cruise are as follows:

• Launch of 5 Bio-Argo floats, purchased as part of a successful NERC Capital bid by PML, in the sparsely sampled remote tropical Atlantic;
• Launch of 8 Argo floats on behalf of the UK Met Office in the tropical and south Atlantic;
• Recovery of two deep (5000 m) sediment trap moorings in the South Atlantic Gyre for NOC, which had previously been deployed in October 2012 and May 2014, and the construction and deployment of a single sediment trap mooring at the same location. The entire operation was achieved in less than 30 hours;
• Automated process, partly developed and designed on AMT24, to seamlessly send coarse resolution CTD data to the UK Met Office for assimilation into atmosphere / ocean forecasts;
• Seventy CTD profiles at stations spaced approximately 200 nM apart measuring key physical and biogeochemical parameters including: temperature, salinity, chlorophyll, oxygen, nutrients, pH, alkalinity, N20, CH4, phytoplankton and zooplankton abundance, primary production, respiration, genetics and microbial dynamics;
• Thousands of underway bio-optical and biogeochemical measurements covering a 100° range in latitude and vastly contrasting ocean biomes;
• Continuous operation of acoustic sensors to continuously calculate biomass;
• Twice daily trawls of a range of nets to determine the abundance of different species of zooplankton;
• Marine grade extended endurance testing of hyperspectral spectrometers designed to accurately determine direct and diffuse irradiance. This was part of an industrial partnership with Peak Design Ltd.;
• Participation of 24 research scientists from 13 institutes (UK, Netherlands, USA)

The image above shows the route taken by the cruise including sampling at the North and South Atlantic Gyre. The yellow points are stations, red points are Met Office floats, green points are PML bio-Argo floats and the ‘M’ symbol is a mooring.