B-DEOS Plans for establishment of long-term mobile interdisciplinary
ocean observatory systems in the N and S Atlantic
Adam Schultz1, Richard Lampitt2, Christine Peirce3, Evan Boyle4
1
3
1

adam@ocean.cf.ac.uk, 2Richard.S.Lampitt@soc.soton.ac.uk,
Christine.Peirce@durham.ac.uk, Evan.Boyle@kvaerner.com

Cardiff Marine Institute, Cardiff University, Earth Science Department, Cardiff CF10
3YE, UK; 2George Deacon Division, Southampton Oceanography Centre, European
Way
3Southampton SO14 3ZH, UK; Department of Geological Sciences, University ofDurham,Durham, DH1 3LE , UK; 4Kvaerner Engineering & Construction Australia Pty Ltd.

Introduction
Advances in theoretical understanding of
the natural systems in the sea and in the
Earth below have been closely associatedwith new data sets made possible by technological advances. Important and unanticipated processes have been revealed as aresult of new capabilities in acquiring marine data. The plate tectonic revolution, thediscovery of hydrothermal circulation, andmany other examples can be attributed tothe application of innovative new technology to the study of the sea.
A consortium of research groups and institutions within the United Kingdom isplanning a regional system of multidisciplinary ocean observatories to study thelinkages between the physical, chemicaland biological processes regulating theearth-ocean-atmosphere-biosphere system.
Funds have been released for engineering
activities leading to the design of the basic
mooring and telecommunications/power
buoy system, and a UK NERC Thematic
Programme is in the planning stage.
The B-DEOS (British - Dynamics of Earthand Ocean Systems) observatory system isdesigned to allow studies on scales of order 10-3-102 km, as well as to supplement
on larger spatial scales the emerging
global ocean and seafloor solid earth observatory network. The facility will makeit possible to obtain requisite long-term

synoptic baseline data, and to monitor
natural and man-made changes to this system by:o Establishing a long-term, permanentand relocatable network of instrumented seafloor platforms, mooringsand profiler vehicles, provided withpower from the ocean surface and internal power supplies, and maintaining
a real- or near-real time bidirectional
Internet link to shore.
o Examining the time varying propertiesof these different environments (solid
earth, ocean, atmosphere, biosphere),
exploring the links between them andthe causes of the variability.
o Developing appropriate methods ofacquiring data in real-time, assimilating them into mathematical models of
the solid earth, oceans, and air-oceaninterface, and promoting interpretationof these data for a truly synoptic understanding of the linked earth-oceanatmosphere-biosphere system and its
components.
Feasibility: Major advances in technology
have demonstrated the potential of geophysical and oceanographic sensors
mounted on deep water seafloor platforms
and moorings for recording and transmitting data to the surface. Major advances
have also been made in the oceanographic
disciplines over the past decade such that awide variety of marine properties can nowbe measured in situ over prolonged time
periods (eg nutrients, phytoplankton concentration, aqueous geochemistry, ocean
currents and temperature). Furthermore
developments of subsurface vehicles tocarry such sensors are nearly ready forlarge scale deployment. Satellite telecommunications enable these data to be transmitted from remote areas (inaccessible toshore cables) to land-based data centres inreal-time for dissemination via the Internet.
These Internet links make it possible forshore-based scientists to modify experimental parameters and instrument operations remotely in response to changing environmental or engineering conditions.
A UK Natural Environment Funding
Council supported feasibility study by anacademic-industrial partnership (Cardiff
University, Kvaerner Oil & Gas Australia
Pty Ltd, Southampton Oceanography Centre) has culminated in a design specification for a permanent ocean observatorycommunications and power supply buoysystem. The observatory buoy platform
and moorings will be deployable from thelargest class of research vessels available
to the UK fleet (e.g. RRS James Clark
Ross), or international equivalents. The
scientific rationale for such an observatory
system is summarised below, and the enabling technology of large ocean
power/telemetry buoys envisaged for BDEOS is outlined.
Science planning:
Our efforts are part of a larger international requirement for sustained multidisciplinary ocean-based observatories.
The present proposal falls under the umbrella of DEOS (Dynamics of Earth andOcean Systems), an initiative in advancedplanning in the UK and the US (further
information about the DEOS observatory
programme
may
be
found
at
www.deos.org). Intersections between B-

DEOS and other international ocean observatory efforts such as Euro-GOOS and
CLIVAR are also taken into consideration.
The B-DEOS draft science plan currently
calls for establishing in the first instancethree observatory locations, employing at
each a relocatable 200 km long 1D arrayof oceanographic sensors bisecting a 50
km on a side 2D array of multidisciplinary
sensor platforms. This scenario is based on
the staged installation of the first observatory at a high latitude N Atlantic site. Afteran initial operating period of three years,
the bulk of the observatory array will be
relocated to the next observatory site. The
central node in the array is to be left inplace, and modified for very long term operation as part of the global system ofpermanent geophysical and meteorologicalstations. The process will be repeated asecond time, resulting in establishment of
three sites in the N and S Atlantic andSouthern Oceans. From an engineering
perspective, the instrument array, buoys
and moorings have been specified to satisfy the operational and scientific requirements in each of the potential target areas.
Initial observatory site - Reykjanes
Ridge:The location proposed for the first deployment of the UK observatory array is a
200 km long (E-W) by 50 km wide (N-S)
area centred on the Reykjanes Ridge – thesection of the slow spreading Mid-Atlantic
Ridge extending southwards from Iceland
to the Charlie-Gibbs transform system.
The Reykjanes Ridge represents an area of
the North Atlantic at which multidisciplinary data collected by the observatory array will be able to address fundamental questions relating to biogeochemical fluxes and cycling; to ocean circulation; and to the dynamics of the upper
mantle and sea floor spreading. This also
serves as a component in the global observatory array.

Fig 1. Location of 50 km × 50 km dense observatory instrument array centred on
Reykjanes Ridge, with 200 km long 1D instrument transect bisecting the array. Thisconfiguration permits study of local, regional and global scale processes. Each pointin the array comprises three seafloor landers and a mid-water relay buoy forming a 10
km on a side triangle for high resolution site-specific studies.
The initial location of the observatory array has been chosen to allow optimum
resolution of the uppermost mantle – between the Moho and 200 km depth – beneath the Reykjanes Ridge. Geophysicalobservations are used to image the structure of the uppermost mantle, and to determine if the upper mantle structure isconsistent with expectations based onmodels of tectono-magmatic cycles. Suchinformation provides the basis for a newgeneration of predictive geodynamic models of mantle matrix flow, melt generationand melt extraction that take full accountof time variations and their interactions
with ridge segmentation.
Geophysical measurements, methodology and array geometry
The geophysical component of the observatory (the central 50 km by 50 km “box”
seen in Fig 1) is currently planned to comprise 36 bottom lander sites organised into
12 sub-arrays, all measuring long-period
seismic and electromagnetic data (e.g.

magnetotelluric <<MT>> data). Each subarray consists of 3 multi-component instrumentation platforms arranged around acentral telemetry mooring (Fig. 1, 2), andeach separated from the other platforms by
10 km. Electromagnetic data will be collected by biaxial electric field sensors, andtriaxial magnetometers. Seismic data will
be collected by triaxial, broadband Güralp
seismometers and/or differential pressuregauges. The geometry of the array is optimised to allow adequate spatial coveragefor the magnetotelluric sounding, and willallow surface wave phase velocities to bemeasured at periods from 10 s up to atleast 60 s, where the data have the best
signal to noise ratio and provide thestrongest constraints on the structures ofinterest.
Ocean physics, air-sea interactions andupper ocean biogeochemistry – theReykjanes Ridge transect
The 200 km-long E-W oceanographic instrument array, i.e. the Reykjanes Ridge

The surface buoy at the centre of each observatory will be instrumented to measure
the fluxes of heat, freshwater and momentum between the atmosphere and ocean.
The transect of time series observatories
across the Reykjanes Ridge offers an opportunity to study the boundary between
two N. Atlantic biogeochemical provinces,
the Atlantic Arctic province (ARCT) to
the Northwest and the North Atlantic Driftprovince (NADR) to the southeast. We
seek to characterise the two provinces
which lie on either side of the Reykjanes
Ridge in terms of their biology and chemistry. This is to be done primarily by acomparison of the oceanographic characteristics at the stations at each end of thecross ridge transect.

Fig 2. Schematic of central telemetry/meteorological mooring supporting
acoustic communications to seafloor instrumentation platforms and to oceanographic mooring.
Transect (Fig 1), is designed to measure
the structure and transport of deep boundary currents on either side of the ridge.
Physical oceanographic and upper ocean
biogeochemical data will be provided by aset of five vertical sub-arrays, distributed
from WNW to ESE across the axis of the
Reykjanes Ridge, and extending laterally
for 200 km and vertically throughout theentire water column. Each vertical subarray will be fitted with standard physicaloceanography sensors, together with a vertical profiling vehicle which will transit atleast once per day through the upper 1000m of the water column. The vehicle willmeasure conductivity, temperature anddepth (CTD), together with chlorophylland zooplankton abundance and size distribution.

As seen in Fig 1, the intention is to deploy
five time series moorings across the ridge,
each of which supports a profiling vehicle
carrying a suite of sensors to characterise
the physics, and biology of the upper 1000m of the water column. Measurements include CTD, chlorophyll and zooplankton
abundance and size distribution with theincorporation of nutrient sensors later inthe program. Profiles will be made once or
twice per day with data being transmitted
in real time acoustically to the surface
buoy, multiplexed with the other geophysical, oceanographic and meterological
data streams, and from there transmitted to
the ground station by satellite.
Eventual permanent observatory installation
Since the array is designed to be a relocatable resource, much like a ship weenvisage transporting it to new observatory locations over time. However one
long-term objective is that the central subarray on Reykjanes Ridge should be left
permanently installed on the ocean floor,
connected directly by power and data cables (rather than by acoustic telemetry,
which is used during the three year wide
area array operations period to relay data
between instrument platforms and the cen-tral satellite communications buoy) to along-lived data telemetry surface buoy, toform part of the DEOS global network ofseismic and geomagnetic observatories.
At the centre of the array we plan therefore to install a communications mooring,equipped with a large, tethered, surface
buoy that will provide the satellite
communications link to shore. The buoy
will also be fitted with a suite of
meteorological sensors, compatible withthose installed by the UK Meteorological
Office on their other autonomous ocean
weather stations.
Future observatory sites - MOMAR,
Scotia Sea-Drake Passage
The Mid-Atlantic Ridge southwest of the
Azores Archipelago contains four sites ofhigh-temperature hydrothermal venting.
These are found along a 200 km section of
the ridge crest in varying geological settings and at a range of different
depths/pressures. The Lucky Strike ventsites are distributed around a lava lake inthe caldera of an axial volcano. The Lucky
Strike segment, lying within EU waters,
provides a natural laboratory (the InterRidge-designated “MOMAR area) for detailed multidisciplinary investigations in arange of seafloor environments, all withinready reach of the Azores.
The MOMAR area is also of wide interest
to researchers into whole water-column
processes. This section of the MAR exhibits a complex hydrography which is further affected by the ridge topography, theMediterranean water tongue and the
Azores current and front.
The water column overlying the ridge
crest within the MOMAR area is noted for
an increased biomass, perhaps linked to
local upwelling around the islands as theridge-crest shoals toward the Azores Archipelago. The intrinsically high biodiversity observed within the mid-water fauna
at these latitudes attracts the interest of awide spectrum of scientists studying
biogeochemical cycles.

The Southern Ocean
The Southern Ocean plays a major role inregulating the Earth’s climate because it
serves as an important conduit for interocean exchange between the Atlantic, Indian and Pacific Oceans via the Antarctic
Circumpolar Current (ACC), which flows
eastward around the Antarctic continent. A
key to understanding the ACC is the
Drake Passage - the natural “choke-point”
between the southernmost tip of SouthAmerica and the northernmost tip of the
Antarctic Peninsula.
Due east of the Drake Passage lies the
Sandwich Plate, which extends just 200
km from the medium-fast spreading East
Scotia Ridge, in the west, to the South
Sandwich Island Arc and trench in the east.
The East Scotia Ridge itself exhibits arange in geological characteristics including at least one axial magma chamber beneath the ridge crest and a minimum of
two discrete hydrothermal fields, locatedat opposite ends of the.
Within this area, the possibility exists toprovide long-term continuous observationsof all the major components of the plate
tectonic cycle in real-time with telemetry
either from moored arrays or through direct cable connections between the seafloor and land-based relay stations installed on the South Sandwich islands
and/or South Georgia, an area of great
strategic interest to the UK in which logitistical support is high.
B-DEOS observatory buoy system
An engineering feasibility study has considered competing designs for a stable,
long-term buoy system to support seasurface power generation, transmission of
power to the seafloor, and bidirectional
telemetry from the above-mentioned instrument array sites to/from the Internet.
Disc buoys have the majority of their volume above or at the waterline resulting invery small heave natural periods (below

the wave period) and consequently follow
the sea surface resulting in relatively large
motions. Spar-type buoys have the ability
to modify their natural period and hence‘tune’ the response in union with the sea
surface. The superior motion characteristics of spar buoys give advantages in termsof satellite communications and reliability,
as well as mooring system load.
The B-DEOS spar buoy (Fig 3) is characterised by two sections of different diameters and a conical transition. Differing diameters allow for ‘tuning’ of the buoy toobtain the most favourable motion response. For SPAR type buoys the natural
period is largely dependent on the surfacepiercing diameter. Further ‘tuning’ of thebuoy response may be carried out by including a heave-suppression plate aroundthe keel. This allows for additional added
mass which ensures the heave natural pe-

riod of the buoy is in excess of any anticipated wave periods.
Design service life
The buoy internal and external systems
and coatings have a design life of 20 years,
with 10 years between major refurbishment (involving recovery of the buoy andsubsequent redeployment). The buoy hull
structure has been designed for a design
life of 2 refurbishment periods (20 years),assuming a scheduled maintenance periodof 2 years. This is based around a preventative maintenance program, including refuelling, replacement of consumables suchas lubricants, and replacement of relatively
low reliability items.
Proposed Locations
To date, four buoy locations have been
proposed for the B-DEOS program:
1 58 N 33 W
2 37.3 N 32.25 W
3 59 S 63 W
4 59 S 27 W

Reykjanes Ridge
MAR axis close to Lucky
Strike, 250nm S. of Azores
Centre of Drake Passage
Midway between E Scotia riseand S.Sandwich Islands

Operations at water depths of 2500, 4000
and 6000 m have been considered during
the design phase.
Operating Condition

Fig 3. B-DEOS buoy schematic showing
two sections of different diameter for tuned
response, and INMARSAT antenna dome.

Data communications requirements dictate
the use of an INMARSAT/B-HSD arrayfor the primary system, necessitating anactively stabilised antenna unit. This
places a limitation on the buoy motions tomeet the specified design communications
uptime of 95% within each monthly period.
Wave heights occurring at Reykjanes
Ridge are greater than for the other locations for all return periods, and therefore
wave height data from this location only
has been used for design.

The wave periods chosen in the buoy design specification is generally equivalent
to a Beaufort seastate of 6/7 (high/veryhigh). Wave directionality is not a significant design parameter, as the mooring system is not taut, and the buoy will be able
to rotate easily inside its watch circle.
Heave and pitch are driven by a combination of wave forcing and dynamics. The
wave forcing has two components: pressure driven and inertia driven.
The dynamic behaviour is characterised bya sharp resonant peak at the heave natural
period. If the forcing cancellation andheave natural period coincide, heave motion is minimised over the operating range.
This cancellation period can be manipulated by changing the geometric propertiesof the buoy; specifically the relative diameters of the cylinders and the cone angles. Heave motion can also be reduced byincreasing vertical damping, over the frequency range where the dynamic component is large.
Servicing
The intent is that the buoy will be accessible for servicing and retrieval at least 3
months during the year. Servicing of thebuoy will be carried out by either retrieving the buoy onto the deck of a vessel (either a research vessel or a supply boat) for
repairs or maintenance or using standard
connections for replenishment. The designof the payload package of the buoy is toallow simple removal and replacement of
all major components in package form,
with all connections between package systems and buoy hull systems to be made ata single location where possible. Servicingof seafloor packages will be possible by
ROV, including the new UK national deep
submergence facility currently being established.
Payload Requirements
The payload requirements are:

•

•
•
•

Electronics Package− Buoy Control CPU− Telemetry CPU / Communications control hardware− Distribution panels
Battery Package - Batteries for
1000W continuous use
Generator Package - 1.5 kW generator for recharging the batteries
Fuel Bladders - 6000 litres of fuelin independent bladders

Mechanical/Buoy Systems
In addition to the equipment included in
the payload package, there will be various
equipment installed on the buoy hull structure to enable it to function. This shall include the following.
Inmarsat radome antenna array(approx. 1m diameter), other antennae
as required
Piping systems (fuel, exhaust, ballast,
etc.)
Bilge pump
Hazard detection
Navigation Aids, including lights
Compartment access ways and seals
Interface connectors
MetOcean equipment
Power Generation and Supply
One of the major requirements of the buoy
is to generate power for both subsea instrumentation and for buoy systems. Given
the limitations of the buoy in terms of size,
weight, and reliability requirements, thebase case is diesel power generation.
However, it is important that alternatemeans of power generation are investigated, as significant improvements in reliability and fuel efficiency may be possible.
Possibilities may include fuel cells, windor wave power generation, or other emerging technologies.

Power requirements are initially definedas: 1.0 kW for the buoy system, with 0.5
kW delivered to a subsea junction box forprovision of subsea instrumentation packages. Power losses along the umbilical/mooring line can be significant (asmuch as 50%). The power supply methodology is DC current, 110V to maximise
supply efficiency. Based on these requirements, the power generation capacity
required at the buoy is estimated to be 2.0
kW.
Satellite Data Transmission
The satellite telemetry requirements of thescientific payload are planned to lie within
the capabilities of a 64 kbps communications link (additional effective bandwidth
may be obtained through the use of datacompression techniques). The most costeffective system to achieve this bandwidthis INMARSAT/B-HSD (high speed data)
which can provide either 56 or 64kbps of
bandwidth. There are a number of competing satellite systems proposed for installation over the next decade, which would
also be capable of providing this bandwidth in a cost-effective manner. However,recent experience has shown that at least
some of these proposed systems will beabandoned before installation. B-DEOS
have therefore implemented a conservative
design, under the assumption that nonINMARSAT options will have less stringent antenna stability requirements, andtherefore all alternatives may be accommodated safely within the operating margins for INMARSAT/B-HSD.
Based on the use of INMARSAT/B-HSD
a gyroscopically stabilised antenna is required to maintain the pointing accuracy
needed by the INMARSAT system. However, the more that these motions can be
reduced through the design of the buoy,
the less complexity and power is requiredby the stabilising system and the greater
the reliability.

Other backup systems are to be provided,
including an emergency beacon, GPS positional data collection, and lower bandwidth data transmission via LEO satellite(omnidirectional antenna) in the case of a
failure of the INMARSAT system.