Research and impact

Latest results

The most recent Extended Ellett Line cruise took place in July 2014.  Some products from the data are shown in the figures here; the temperature and salinity data are averaged by basin in order to pick out changes over time.  The map uses colour to show the station positions that correspond to the coloured lines in the next panels.

map showing Extended Ellett Line station positionsThe first set of graphs show temperature and salinity averaged over 30-800m in the Rockall Trough (black line) and Hatton-Rockall Basin (red line), and averaged over 30-600m in the Iceland Basin (blue line).  Excluding the upper 30m reduces any bias by undersampling the strong seasonal cycle, though does not completely remove it.  The temperature and salinity in 2014 were low compared to the previous 10 years, suggesting that the North Atlantic subpolar gyre has increased in circulation and expanded, bring cooler, fresher water into the eastern regions.

time series of upper ocean temperature and salinity

 

The second set of graphs shows the temperature and salinity of an intermediate water mass, the Labrador Sea Water (at around 1800m) in the Rockall Trough (black line) and the Iceland Basin (blue line).

time series of upper ocean temperature and salinity

 

Most recent major finding

The most recent significant discovery from the Extended Ellett Line is the periodic presence of Wyville Thomson Overflow Water which influences the temperature and salinity at the depth of the permanent pycnocline (800-1200m) and is thought to sometimes flow southwards at depth on the western side of the basin.  Early hydrographic data and the erosion of bottom sediments on the Feni Ridge suggested the presence of overflow water in the basin, but for the past three decades its influence was thought to be minimal.  It is now recognised that this episodic southward flow needs to be measured and accounted for when calculating the climatically important heat transport through the Rockall Trough.

Impact and advice

Extended Ellett Line data and research are used in climate assessments by the Intergovernmental Panel for Climate Change (IPCC), the UK Marine Climate Change Impact Panel (MCCIP), DEFRA, the International Council for the Exploration of the Sea (ICES), Marine Scotland Science, and the OSPAR Commission.

Stories of extreme weather and waves encountered during Extended Ellett Line cruises form a popular entry point for media stories about the science of the programme.  The Extended Ellett Line has featured in many articles, TV programmes and books (including a New York Times bestseller).


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