Cruise inventory

RV Prince Madog PD21/06

Cruise summary report

Cruise Info. 
Ship name (ship code)RV Prince Madog (74P2)
Cruise identifierPD21/06
Cruise period2006-07-10 — 2006-07-23
StatusCompleted
Port of departureHolyhead, United Kingdom
Port of returnHolyhead, United Kingdom
ObjectivesA combination of techniques will be 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 reportRV Prince Madog PD21/06 cruise report pd21_06.pdf — access key 'C' (0.17 MB) 
Ocean/sea areas 
GeneralIrish Sea and St. George's Channel
SpecificIrish Sea
Track chartsRV Prince Madog PD21/06 cruise track — pd21_06trk.pdf (00 MB) 
Measurements 
Physical oceanography 
Surface measurements underway (T,S)Quantity: activity duration in days = 14
Description: Hydrographic parameters from the ship borne throughflow system
CTD stationsQuantity: number of profiles = 132
Description: Seabird CTD-rosette with Fl/Transmittance Water samples for nutrients and Chlorophyll
Current profiler (eg ADCP)Quantity: activity duration in days = 12
Description: Ship borne ADCP
Other physical oceanographic measurementsQuantity: number of profiles = 1040
Description: FLY dissipation profiler: velocity shear(at1cm scale) for dissipation ADCP vel. +T/S/Fl
Meteorology 
Routine standard measurementsQuantity: activity duration in days = 14
Description: Meteorological parameters from ship borne station
Moorings, landers, buoys 
Physical oceanography 
Subsurface temperature measurements53° 40' 59" N  4° 9' 0" W — bottom mounted 600kHz ADCP, deployed 12/7/06, recovered 14/7/06
Subsurface temperature measurements53° 43' 0" N  5° 30' 0" W — bottom mounted 300kHz ADCP +Temperature chain: 24 thermistors and 2 seacat ctd
Subsurface temperature measurements53° 40' 59" N  5° 22' 0" W — bottom mounted 300kHz ADCP +Temperature chain: 18 thermistors and 2 Seacat ctd
Current profiler (eg ADCP)53° 43' 0" N  5° 30' 0" W — bottom mounted 300kHz ADCP +Temperature chain: 24 thermistors and 2 seacat ctd
Current profiler (eg ADCP)53° 40' 59" N  4° 9' 0" W — bottom mounted 600kHz ADCP, deployed 12/7/06, recovered 14/7/06
Current profiler (eg ADCP)53° 40' 59" N  5° 22' 0" W — bottom mounted 300kHz ADCP +Temperature chain: 18 thermistors and 2 Seacat ctd
Other physical oceanographic measurements53° 40' 59" N  4° 9' 0" W — Aries bottom mountedsidescan sonar, deployed 12/7/06, recovered 14/7/06