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Cruise inventory

MV Terschelling Ter Asub

Cruise summary report

Cruise Info. 
Ship name (ship code)MV Terschelling (PATE)
Cruise identifierTer Asub
Cruise period2006-07-12 — 2006-07-21
Port of departurePlymouth, United Kingdom
Port of returnPlymouth, United Kingdom
ObjectivesThis cruise was in conjunction with RV Prince Madog cruise PD21_06. The following describes the objectives for the combined cruises; the Terschelling was specifically used to deploy Autosub and accommodate the Autosub team.

A combination of techniques were used to map turbulent properties in parallel with mean flow and T/S structure in the contrasting environments of:
(i) tidally well-mixed shelf seas,
(ii) seasonally stratified waters where buoyancy forces inhibit turbulence and internal wave motions may contribute to vertical mixing, and
(iii) the tidal mixing frontal regions separating (i) and (ii).

The new measurements will provide insights into the occurrence and evolution of turbulence and furnish a data base on the distribution of turbulence which is now needed for the understanding of biogeochemical processes in the water column and for the testing of turbulence closure schemes.

Specific objectives :
(i) Determination of the horizontal structure and variability of turbulence in the well-mixed and stratified shelf sea regimes
(ii) Direct measurements of the horizontal variation of turbulence and mixing in the high gradient regions of a tidal mixing front.
(iii) Integrated data sets from simultaneous horizontal and vertical profiling to elucidate the evolution of turbulent processes over the tidal cycle and providing a basis for the testing of models of turbulent processes.
(iv) Determination of variations in anisotropy and its influence on estimates of dissipation
(v) Assessment of the potential of microstructure sensors on Autosub for the determination of vertical fluxes of heat.

The programme involved measurements of the horizontal and vertical structure using (i) shear sensors mounted on the Autosub autonomous vehicle, (ii) the FLY free-fall dissipation profiler and (iii) Acoustic Doppler Current Profilers mounted on the seabed and on the research vessel.

Because of the heavy demands of the programme, two vessels were employed for the campaign: the Prince Madog deployed the moorings and undertook the FLY profiling while the Terschelling acted as mother vessel for the deployment and recovery of Autosub and accommodated the Autosub technical team.
Chief scientistJohn H Simpson (University of Wales, Bangor School of Ocean Sciences)
ProjectThe structure of Turbulence(NERC/Dstl)
Cruise reportMV Terschelling Ter Asub cruise report terschelling2006.pdf — access key 'C' (0.39 MB) 
Ocean/sea areas 
GeneralIrish Sea and St. George's Channel
SpecificIrish Sea
Physical oceanography 
Subsurface temperature and salinity measurementsQuantity: track kilometres = 700
Description: Autosub Turbulence measurements, ADCP, T/S/chl fluorescence
Current profiler (eg ADCP)Quantity: track kilometres = 700
Description: Autosub Turbulence measurements, ADCP, T/S/chl fluorescence
Biology and fisheries 
Phytoplankton pigs (eg chlorophyll, fluorescence)Quantity: track kilometres = 700
Description: Autosub Turbulence measurements, ADCP, T/S/chl fluorescence