Extremes of temperature and salinity during the 1990s in the northern Rockall Trough: results from the “Ellett line”

A time-series of deep hydrographic measurements in the northern Rockall Trough is analysed to determine the nature and origin of interannual to decadal variability of water mass properties. The repeat section (Barra Head to Rockall Island) was started in 1975 by David Ellett of Dunstaffnage Marine Laboratory and has been occupied between one and six times per year since then. Both the surface and deep water masses have shown extremes in their properties during the past decade compared to the previous 15 years. The 1990s began with relatively low temperature and salinity in the surface water mass (Eastern North Atlantic central Water, ENAW ), but since 1995 there has been a dramatic increase, culminating in the highest salinity in 1998 and highest temperature in early 2000. In contrast, the deep Labrador Sea Water (LSW) is fresher and cooler in the late 1990s than at any time in the series. The ENAW  is subject to local modification by exchange of heat and freshwater with the atmosphere, but the variability is mainly determined by mixing with other water masses at the southern entrance to the Rockall Trough. The LSW is a re-circulating reservoir periodically flushed by newer water from the southwest.

Article from Marine Science Symposia Vol. 219 - "Hydrobiological variability in the ICES Area, 1990-1999", symposium held in Edinburgh, 8-10 August 2001. To access  the remaining articles please click on the keyword "MSS Vol. 219".