About the Ellett Array

The Extended Ellett Line is a project to measure and understand the ocean west of the UK. We are looking at how and why the currents, temperature and salinity have changed over the past few decades.  We also investigate the impact those changes have on ecosystems and local climate.

Each year UK marine scientists cross the deep ocean between Scotland and Iceland on a research ship. Along the way the scientists measure the velocity, temperature and salinity of the ocean; at points 30 km apart, the ship stops and instruments are lowered though the water all the way to the seafloor. Water samples are also collected and analysed for a range of chemicals (including iron, nutrients and carbon) and biological content (including phytoplankton). The project is one of a small number of high-quality, long-term marine data sets in the North Atlantic Ocean and helps us to understand changes in ocean climate. It is relevant to the UK and northwest Europe because the warm water flowing past the Extended Ellett Line keeps winters warmer than expected for this latitude.

The history of the Extended Ellett Line began in 1948, when Jack R. Lumby of the Fisheries Laboratory in Lowestoft, UK, realised that use could be made of the regular passage of ships to the Ocean Weather Stations of the North Atlantic. These ships of opportunity collected underway measurements of sea surface temperature and salinity until 1996. From 1975 to 1996, scientists concentrated on the Rockall Trough, measuring the warm salty subtropical water flowing northwards west of the UK and Ireland. Since 1996 the annual expeditions travel as far Iceland in order to measure all the warm water that flows into the Nordics Seas from the eastern North Atlantic. We also measure cold northern water flowing southwards at the bottom of the sea.

Why is it important?

A key part of the global climate system is the Meridional Overturning Circulation (MOC), which carries heat and salt northwards in the upper layers of the Atlantic Ocean and cooler, fresher water southwards in the deep layers. In the subpolar region of the North Atlantic the northward transport takes places largely in the North Atlantic Current which travels through the Iceland Basin and Rockall Trough in a series of jets and eddy trains, continuing into the Nordic Seas and Arctic Ocean. The returning deep branches are made up of water cooled and freshened in the Arctic, the Nordic Seas and the subpolar North Atlantic itself. By making measurements on the Extended Ellett Line we can investigate the dynamics and variability of the northward-flowing warm saline water, including the interaction between the wind-driven cyclonic circulation of the subpolar gyre and the MOC. Around half of the returning dense water flows through the Iceland Basin, so by combining measurements from this region with partner programmes that capture the remaining dense flows, we can understand the key processes driving them.

Conditions in the subpolar gyre are important for skillful decadal climate predictions, including the location of the Atlantic Inter-Tropical Convergence Zone and the number of tropical storms. Important climate impacts including rainfall in the African Sahel, Amazon, western Europe and parts of the US, are associated with subpolar gyre and North Atlantic variability. Present-day ocean and climate models are still unable to accurately represent the MOC in the subpolar region; only by understanding the physics of the system can we hope to improve the models.

Changes in the physical conditions also profoundly affect the ecosystem of the region, from plankton to whales and birds. With changing conditions, key species change their feeding and breeding ranges, with subsequent impact on the health and exploitation of our seas.

What do we do?

The overall aim of the Extended Ellett Line programme is to improve our understanding of the character, causes and effects of interannual to multi-decadal variability of the eastern subpolar North Atlantic. The specific objectives are to

1. provide a long-term multidisciplinary ocean observation programme.
2. provide a platform for national and international scientific collaboration
3. lead international research in the region
4. be part of integrated global ocean observing programmes
5. provide training for the next generation of marine scientists and engineers
6. develop the transition from long-term ship-based observation programmes to autonomous surveying by gliders
7. deliver advice to government and other stakeholders

Why Ellett?

The section was named after the man who started the hydrographic time series in the Rockall Trough in 1975.

David James Ellett (born 22 July 1934) began his career in ocean science when he moved to the Lowestoft Fisheries Laboratory in January 1954 . Over the next decade he learned Atlantic hydrography by participation in wide-ranging cruises to the Barents Sea, North Sea, Irish Sea and Atlantic, including, notably, the ICES Faroe-Iceland Overflow Experiment of 1958. With long spells on both Irish and UK Weather Ships, this period also saw the beginnings of his life-long involvement with Ocean Weather Ships and their data.

The Rockall Trough was to be David's main working area and interest to the end of his career, bringing a succession of new insights to what had so long been a data desert; the so-called "shadow of Europe". His collaboration with Dunstaffnage Marine Laboratory (Oban) began when he sailed with them aboard RRV "Challenger for the second ICES Overflow Survey in 1973. This led to his secondment in 1975 and ultimately to his transfer to Oban. Until his official retirement in 1994, he thoroughly explored these waters, deploying the first long-term current-meter moorings in the Trough from 1975, planning then participating in the JASIN Air-Sea Interaction Experiment in 1978, recovering the first unequivocal evidence of a slope current west of Scotland in 1979, and making the first direct measurement of overflow crossing the Wyville-Thomson Ridge in 1987/1988.

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Individual Sections

Details of the individual sections that make up the Extended Ellett Line time series are given in this table. The cruise numbers provide links to the BODC cruise inventory pages where you can find details of the data collected, cruise tracks and cruise reports. The icons in the right hand column provide links to plots of the data (n/a denotes cruises for which data are not shown due to poor data quality).

Cruise	Cruise Dates	Chief Scientist	Institute	Ship	Section Plot
DY078	6–28 May 2017	N. P. Holliday	NOC	Discovery
DY052	7 - 24 Jun 2016	S. Gary	SAMS	Discovery
DY031	29 May - 17 June 2015	N.P. Holliday	NOC	Discovery
JR302	6 Jun – 22 Jul 2014	B. King and N. P. Holliday	NOC	James Clark Ross
JC086	6–26 May 2013	C. Griffiths	SAMS	James Cook
D37912	30 Jul – 17 Aug 2012	C. Griffiths	SAMS	Discovery
D36511	11 May – 2 Jun 2011	J. Read	NOCS	Discovery
D35110	10–28 May 2010	J. Read	NOCS	Discovery
D34009	10–25 Jun 2009	T. Sherwin	SAMS	Discovery
SC0805*	6–25 May 2008	T. Sherwin	SAMS	Scotia
D321b07	24 Aug – 9 Sep 2007	T. Sherwin	SAMS	Discovery
D321a07	24 Jul – 23 Aug 2007	J. Allen	NOCS	Discovery
D31206	11–31 Oct 2006	J. Allen	NOCS	Discovery
CD176	6–28 Oct 2005	T. Sherwin	SAMS	Charles Darwin
P314	11 Jul – 23 Jul 2004	J. Read	SOC	Poseidon
P300*	19 Jul – 6 Aug 2003	C. Griffiths	SAMS	Poseidon
SC0703*	15 Apr – 5 May 2003	W. Turrell	MarLab	Scotia
DI25301	4 May – 20 Jun 2001	J. Allen	SOC	Discovery
SC0700*	15 Apr – 5 May 2000	W. Turrell	MarLab	Scotia
DI24500*	27 Jan – 20 Feb 2000	N.P. Holliday and C. Griffiths	SOC and DML	Discovery
DI24299	7 Sep – 6 Oct 1999	S. Cunningham	SOC	Discovery
DI23398	2 Apr – 1 Jun 1998	D. Smythe-Wright	SOC	Discovery
DI23097	7 Aug – 17 Sep 1997	S. Bacon	SOC	Discovery
DI22396	28 Sep –21 Oct 1996	H. Leach and R. Pollard	Univ. Liverpool and SOC	Discovery
C12496	21–25 Jan 1996	A. Edwards	DML	Challenger	n/a
C12095	18 Jul – 6 Aug 1995	A. Edwards	DML	Challenger
CD9295	13 Apr –2 May 1995	A. Edwards	DML	Charles Darwin	n/a
C11694	17–29 Aug 1994	C. Griffiths	DML	Challenger
C11494	15–29 Aug 1994	J. Graham	DML	Challenger
C11294	28 Apr –13 May 1994	D.J. Ellett	DML	Challenger
C11094	10–20 Mar 1994	D.J. Ellett	DML	Challenger
C10593	3–16 Sep 1993	A. Edwards	DML	Challenger
C10393	12–24 May 1993	D.J. Ellett	DML	Challenger
C10193	13–20 Mar 1993	A. Edwards	DML	Challenger	n/a
C9792	25 Sep – 6 Oct 1992	A. Edwards	DML	Challenger
C8191	1–8 Jul 1991	D.J. Ellett	DML	Challenger	n/a
C7591	23 Feb – 3 Mar 1991	J. Gordon and D.J. Ellett	DML	Challenger	n/a
C7190	29 Aug – 5 Sep 1990	D.J. Ellett and J. Gordon	DML	Challenger
C6790	21 Jun – 29 Jul 1990	D.J. Ellett	DML	Challenger
CD4489	24 Nov – 2 Dec	A. Edwards	DML	Charles Darwin
LF289	4–10 Aug	D.J. Ellett	DML	Lough Foyle
LF189	5–11 May 1989	D.J. Ellett	DML	Lough Foyle
D18089	20 Jan – 4 Feb 1989	D.J. Ellett	DML	Discovery
C3088	6–23 Jun 1988	D.J. Ellett	SMBA	Challenger
C2588	24 Feb – 7 Mar 1988	D.J. Ellett	SMBA	Challenger	n/a
C2287	23 Nov – 5 Dec 1987	D.J. Ellett	SMBA	Challenger	n/a
C1487	24 Apr – 7 May 1987	D.J. Ellett	SMBA	Challenger
C987	8–22 Jan 1987	A. Edwards	SMBA	Challenger
C885	14–28 Aug 1985	D.J. Ellett	SMBA	Challenger
C485	2–16 May 1985	D.J. Ellett	SMBA	Challenger
C185	20 Jan – 5 Feb 1985	D.J. Ellett	SMBA	Challenger
C1084	16 Nov–6 Dec 1984	A. Edwards	SMBA	Challenger
C284	23 Jun – 8 Jul 1984	D.J. Ellett	SMBA	Challenger	n/a
C1183	10–24 Aug 1983	D.J. Ellett	SMBA	Challenger	n/a
C783	23 May – 2 Jun 1983	R. Bowers	SMBA	Challenger
C1582	16–30 Oct 1982	D.J. Ellett	SMBA	Challenger	n/a
C782	26 Apr – 16 May 1982	R. Bowers	SMBA	Challenger	n/a
C1581	6–20 Oct 1981	A. Edwards	SMBA	Challenger
C1081	4–14 July 1981	D. Meldrum	SMBA	Challenger
C681	6–25 Apr 1981	D.J. Ellett	SMBA	Challenger
C281	26 Jan – 4 Feb 1981	D.J. Ellett	SMBA	Challenger
C780	21 Apr – 6 May 1980	D.J. Ellett	SMBA	Challenger
C480	26 Feb – 7 Mar 1980	D. Meldrum and J. Gage	SMBA	Challenger	n/a
C1679	28 Oct – 11 Nov 1979	D.J. Ellett	SMBA	Challenger
C1379	11–16 Sep 1979	D.J. Ellett	SMBA	Challenger
S579	19 Jun – 2 Jul 1979	D.J. Ellett	SMBA	Shackleton	n/a
C779	10–23 May 1979	D.J. Ellett	SMBA	Challenger
C1478	4–11 Nov 1978	D.J. Ellett	SMBA	Challenger
C11D78	3–17 Sep 1978	A. Edwards	SMBA	Challenger
C11B78	29 Jul – 2 Aug 1978	D.J. Ellett	SMBA	Challenger
C978	31 May – 10 Jun 1978	D.J. Ellett	SMBA	Challenger
C678	11–21 Apr 1978	D.J. Ellett	SMBA	Challenger
C278	30 Jan – 13 Feb 1978	D.J. Ellett	SMBA	Challenger
C1377	20 Aug – 3 Sep 1977	D.J. Ellett	SMBA	Challenger
C1177	12–26 Jul 1977	D.J. Ellett	SMBA	Challenger	n/a
C677	14–19 Apr 1977	D.J. Ellett	SMBA	Challenger
C477	25 Feb – 11 Mar 1977	D.J. Ellett	SMBA	Challenger
C1776	7–20 Dec 1976	D.J. Ellett	SMBA	Challenger	n/a
C1576	7–16 Oct 1976	R. Bowers	SMBA	Challenger	n/a
C1276	4–15 Aug 1976	D.J. Ellett	SMBA	Challenger	n/a
C876	19 May – 1 Jun 1976	D.J. Ellett	SMBA	Challenger
C5a76	29 Mar – 5 Apr 1976	D.J. Ellett	SMBA	Challenger
C1475	7–12 Nov 1975	D.J. Ellett	SMBA	Challenger
C1275	26 Aug – 2 Sep 1975	D.J. Ellett	SMBA	Challenger	n/a
C1075	4–10 July 1975	D.J. Ellett	SMBA	Challenger
C775	1–6 May 1975	D.J. Ellett	SMBA	Challenger
C375	4–13 Mar 1975	D.J. Ellett	SMBA	Challenger	n/a

Station List

This table gives the standard positions for Extended Ellett Line stations. The positions are nominal and not all cruises will manage to occupy all stations.

Station	Latitude	Longitude	Nominal Depth (m)
1G	56.667	-6.133	190
2G	56.683	-6.283	30
3G	56.708	-6.367	70
4G	56.733	-6.450	115
5G	56.733	-6.600	80
6G	56.733	-6.750	40
7G	56.733	-7.000	140
8G	56.733	-7.167	170
9G	56.733	-7.333	160
10G	56.733	-7.500	215
11G	56.733	-7.667	110
12G	56.758	-7.833	50
13G	56.783	-8.000	110
14G	56.808	-8.167	120
T	56.837	-8.333	130
15G	56.883	-8.500	125
S	56.950	-8.783	125
R	57.000	-9.000	300
Q	57.050	-9.217	500
Q1	57.075	-9.317	800
P	57.100	-9.417	1400
O	57.150	-9.700	1900
N	57.233	-10.050	2100
M	57.300	-10.383	2300
L	57.367	-10.667	2000
K	57.400	-10.867	800
J	57.450	-11.083	550
I	57.467	-11.317	750
H	57.483	-11.533	2020
G	57.492	-11.850	1800
F	57.508	-12.250	1800
E	57.533	-12.633	1650
D	57.542	-12.867	1000
C	57.550	-13.000	330
B	57.567	-13.333	200
A	57.583	-13.633	100
IB1	57.667	-13.900	150
IB1A	57.801	-14.250	220
IB2	57.950	-14.583	440
IB2A	58.072	-14.960	600
IB3	58.250	-15.333	660
IB3A	58.343	-15.666	1060
IB4	58.500	-16.000	1190
IB4A	58.566	-16.249	1120
IB4B	58.661	-16.501	1170
IB4C	58.757	-16.750	1140
IB5	58.883	-17.000	1160
IB6	58.950	-17.183	890
IB7	59.117	-17.667	970
IB8	59.200	-17.883	1570
IB9	59.333	-18.233	1870
IB10	59.400	-18.417	2420
IB11	59.667	-19.117	2690
IB11A	59.809	-19.500	2700
IB12	60.000	-20.000	2730
IB12A	60.250	-20.000	2600
IB13	60.500	-20.000	2530
IB13A	60.750	-20.000	2500
IB14	61.000	-20.000	2409
IB15	61.250	-20.000	2380
IB16	61.500	-20.000	2230
IB16A	61.750	-20.000	1800
IB17	62.000	-20.000	1800
IB18S	62.333	-19.834	1790
IB19S	62.667	-19.668	1670
IB20S	62.917	-19.551	1400
IB21S	63.133	-19.916	1030
IB22S	63.216	-20.067	670
IB23S	63.317	-20.215	120