European Directory of Marine Environmental Data (EDMED)

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Data set name

Time series data collected by the Tiree Passage current meter mooring (1981 onwards)

Data holding centreBritish Oceanographic Data Centre
CountryUnited Kingdom  United Kingdom
ProjectOceans 2025 Theme 10; Ocean Processes Evidence Group; Marine Environmental Change Network
Time periodFrom 1981 onwards
Geographical area

Tiree Passage, Scottish west coast, mid-way between the islands of Mull and Coll, in the vicinity of 56 38N, 06 24W.


Vertical velocity of the water column (currents); Horizontal velocity of the water column (currents); Temperature of the water column; Salinity of the water column


Current meters; salinity sensor


This multi-decadal time series initially contains water current and temperature data from a single, near bottom instrument. A second, shallower instrument recording the same parameters was subsequently added after several years of successful operation. Conductivity data are similarly integrated into the time series after a further period of operation. The data are typically at hourly resolution. The mooring is situated in the Tiree Passage, between the Isles of Mull and Coll, off the west coast of Scotland. The specific site chosen was where the passage is at its narrowest (10 km), mid-way between the coasts of the two Isles. The mooring site is in water depths of approximately 45 m. Mooring activity began in June 1981 and consisted of a single RCM current meter placed 11 m above the seabed. The mooring design was modified to incorporate a second RCM current meter at 22 m above the seabed from November 1987. Aanderaa conductivity sensors were added at the two depths in 1993, with MicroCAT conductivity sensors being incorporated in 2002. There are some gaps in the record, most noticeably between January 2000 and May 2002, a period when the observations were temporarily suspended. Fishing damage has generated smaller gaps in the data set over the years. This region was chosen as a site for long term monitoring after radiocaesium studies showed that the major part of the water carried northwards from the North Channel in the Scottish coastal current passes between Mull and Coll. The mooring provides data for comparison with tracer studies and for an examination of the roles of wind forcing and buoyancy contributions to the coastal current. Tiree Passage mooring work is led by Colin Griffiths at the Scottish Association for Marine Science (SAMS).

OriginatorsScottish Association for Marine Science

Mark Inall and Colin Griffiths (2003) The Tiree Passage Time Series: 1981 - 2003, MECN

Data web site
OrganisationBritish Oceanographic Data Centre
ContactPolly Hadžiabdić (Head of the BODC Requests Team)

British Oceanographic Data Centre
Joseph Proudman Building 6 Brownlow Street
L3 5DA
United Kingdom

Telephone+44 (0) 782 512 0946
Collating centreBritish Oceanographic Data Centre
Local identifier1048TIREEPASSAGE
Global identifier5774
Last revised2012-02-24