DWOSK4
DWOS/Met Office Mooring K4, 54°57'.0N 12°40'.0W, 6/04/2002 -
30/11/2002
The effect of climate change in the NE
Atlantic on natural variability in UK coastal seas is poorly
understood. To address this a deep water observatory with a
capability for surface and sub-surface monitoring and long-term
data acquisition is being developed under a Defra-funded
collaborative project.
In the first phase of the three-year project, Cefas has modified
the existing sensor and satellite telemetry system used with
SmartBuoy and installed it on a Met Office Open Ocean Data Buoy. In
addition to the standard suite of surface meteorological
measurements on the buoy, the Cefas equipment takes sub-surface
measurements of temperature, salinity, nutrients and phytoplankton
at high frequency. The location of the buoy is beyond the edge of
the continental shelf to the West of the UK.
If successful, it is proposed to develop a vertical profiling
system that will be deployed adjacent to a Met Office buoy. The
other collaborators involved in the design and construction of this
system are DARD, DML, POL and FRS.
Met Office ODAS Buoy deployment at 'K4'
It's the 5th April 2002 and RMAS Salmaid is tied up alongside at
Pembroke Dock, loaded and ready to go to sea.
Cefas staff Dave Sivyer and Dave Pearce are aboard together with
three Met Office personnel from the Marine Engineering Group at
Bracknell, for the first deployment of Cefas marine monitoring
instrumentation on an Ocean Data Acquisition System (ODAS)
buoy.
The Met Office's ODAS buoy 23 is being secured on deck for the
passage to site 'K4' (54°57'N, 012°40'W). The location lies off NW
Ireland, about 150 miles out into the Atlantic Ocean in the middle
of the Rockall Trough.
The Cefas instruments, which monitor and
record water quality parameters sub-surface, can be seen in the
buoy payload area under the buoyant hull.
Part of the Cefas instrument package consists of the proprietary
ESM2 logger and control system (marketed through Eco-Sense) and a
WMS-1 AquaMonitor water sampler (WS Envirotech). The ESM2
internally records salinity, temperature, turbidity and chlorophyll
fluorescence data every 30 minutes. The AquaMonitor collects a
water sample every four days for post-recovery analysis for
nutrients and chlorophyll.
The second part of the Cefas instrument package consists of a
back-up ESM2 logger and a NAS-2E Nutrient Analyser (WS Envirotech).
The backup logger offers redundancy for half-hourly salinity,
temperature, turbidity and fluorescence data. The NAS-2E measures
and stores the concentration of nitrate in the water every six
hours.
The steam from Milford Haven to 'K4' takes 36 hours via the
Fastnet Rock off Southwest Ireland. Finally, early morning on 7th
April 2002, we are on site, ready deploy the mooring assembly and
buoy.
An ODAS buoy stands 6m tall and the buoyant hull is 2.5m in
diameter. With a full payload the buoy weighs in at about five
tonnes.
The 1 tonne sinker is already over the bow and the subsurface
float is lying on foredeck ready to be deployed. Between the float
and the sinker is an acoustic release used to recover the
mooring.
The water depth at 'K4' is over 2800m (1.75 miles). Most of the
3500m of rope used on the mooring have been paid out at this stage.
It is almost time to deploy the buoy.
It is now mid-afternoon. The crane driver and crew all are ready
to begin the lift. A strop from the crane hook is attached to the
lifting eye on the top of the buoy with a shackle and slip pin
arrangement. ODAS 23 swings out over the side of Salmaid and is
lowered into the water. The slip pin is pulled out and the buoy is
safely deployed.
Finally, the members of the Blue Watch team can relax and
congratulate themselves on another successful ODAS deployment! We
would like to thank the crew and officers of RMAS Salmaid, and the
Met Office personnel who sailed with us, for a very successful buoy
deployment and enjoyable sea trip.
