RRS Discovery Cruise 351, 10-28 May 2010. The Extended Ellett Line 2010.

Abstract

The Extended Ellett Line is a full-depth hydrographic section between Iceland, 60°N 20°W, Rockall and Scotland. The original Ellett Line across the Rockall Trough was first occupied in 1975 when measurements were attempted four times a year. In 1996 the line was extended to Iceland and occupied approximately annually. The data form a 35 year time-series of the oceanic conditions west of the British Isles.

The section monitors the characteristics of the warm water inflow into the Nordic Seas and thence to the Arctic, and observes part of the returning cold water outflow with measurements of the Iceland-Scotland Overflow and the overflow of the Wyville-Thomson Ridge into the Rockall Trough.

The 2010 occupation, RRS Discovery Cruise 351, was completed successfully with 48 CTD stations worked between the Iceland and Scotland shelf edges. Additionally, Line G, part of the SAMS observation network of the Scottish continental shelf was completed. Samples were taken for inorganic nutrients, iron and trace metals, bioluminescence and microscope analysis. Incubation experiments were performed to investigate the role of microzooplankton grazing and the speciation of iron, and to investigate the presence of dinoflagellate bioluminescence.

In addition to the planned programme, sampling took place to investigate the extent of the fall out from the ash plume emitted by the Iceland volcano, Ejyafjallajokull, and its impact on the biogeochemistry and productivity of the upper ocean.

A trial tow of SeaSoar and a short survey of the upper ocean over the Anton Dohrn seamount were successfully completed.

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