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Yoyo 2001Ocean ODYSSEYEC MAST III project
Contract MAS 3 -CT97-0130

LODYC/CNRS Paris/France
http//www.lodyc.jussieu.fr/yoyo/francais/Frenchyo
yo.html
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TABLE OF CONTENTS
Introduction
History Follow-on
Profiler vehicle
Yoyo 2001
Future
Banyuls
final test
Mooring line
Field tests
Casablanca and Blanes
Surface Buoy
ANAIS
Payload
Sensors
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INTRODUCTION
Within the MAST III-EC funded YOYO 2001-Ocean
ODYSSEY project (1998-2001) , an autonomous in
situ multidisciplinary ocean observatory was
developed which provides a wide range of
oceanographical data over the top 1000m of the
water column. The main scientific objective is
to monitor over the mixed layer and the main
thermocline the complex physical and
biogeochemical interactions governing the carbon
cycle and its associated elements in the ocean.
Auotnomous profiling up to the surface opens a
wide range of possible scientifis applications
ranging from specific process studies to climate
monitoring.

This project involves some major technological
challenges in term of development of novel
sensors, data transmission, the profiling vehicle
itself and the mooring (a new surface buoy was
developed). The system is totally integrated
the YOYO 2001 profiler supplies the energy for
all sensors the central brain of the vehicle
commands the sampling acquisition of each sensor,
stores the data in memory and sends it at the
proper time of transmission. The profiler adapts
its rising and descending speed to the sampling
strategy and the response time of the various
sensors. This eulerian profiling instrument
package permits long term in situ monitoring of
the ocean and is an important component of the
Global Ocean Observing System (GOOS).
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FOLLOW-ON OF A SUBSURFACE YOYO
The YOYO-2001 project is to follow-on of a
subsurface yoyo (Provost and du Chauffaut,
1996-1998) and benefits from the experience and
skills gained in the course of development and
testing of the latter. The YOYO is moved by a
change of flotation due to pumping in and out
hydraulic oil from an external bladder to an
internal reservoir.This subsurface YOYO moves up
and down along a taut cable of a subsurface
mooring between a depth of 100 meters and a
subsurface depth of about 50 meters.
Subsurface YOYOs q- are deployed at the equator
and 20W within the PIRATA mooring array (in the
Atlantic) and at 41S and 5530W within the
Brazil Malvinas Confluence (South West Atlantic).
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YOYO 2001A 2 BODY-YOYO
For the project YOYO 2001 Ocean Odyssey, LODYC
designed a new concept of profiler adapted to
carry as many sensors as needed.
Conversely to the former, this profiler is a two
body yoyo, one body being the vehicle part
(similar to the existing subsurface yoyo), and
the second body being the sensor carrier part,
containing the control card and energy packs for
the sensors.
An horizontal arm permits minimizing shading
effects on the light sensors.
The construction of the YOYO and the mechanical
interface for the various sensors was made by SME
ECA.(Toulon,France)
The new electronic for the command card for the
various sensors involved in the project Yoyo 2001
is based on a modular system using the bus I²C
technology.
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THE SURFACE BUOY
The surface buoy has to allow the Yoyo profiler
to reach the surface. The Yoyo profiler has a
one meter long horizontal arm holding the optical
sensors. A hole of 5 meter diameter makes it
possible for the Yoyo to reach the surface
without damage during 90 of the time in the Gulf
of Lion. When the weather is too bad, Yoyo told
not to reach the surface.(It doesnt go higher
than -20m)
The buoy looks like a small offshore 6 legged
rig. This shape was chosen because of its
stability to pitch and roll. A derrick on top
the legs holds the buoy payload and the cable
along which the profiler will move up and
down. The buoy is made of a steel part and an
aluminium partthe steel part was built in
Romania (Contantza) and the aluminium part was
built in France. It was deployed in the
Mediterranean Sea offshore Banyuls in March 2001.
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MOORING
Until 1998, the YOYO mooring was a subsurface
mooring, that is to say it was totally under the
surface mooring. It was a subsurface float which
was load to maintain the mooring in a vertical
position. A surface buoy was load to transmit
measures to an Argos satellite thanks to an
acoustic link.
In order to go to the surface, the mooring has
to be modified. It is a two legged mooring with
intermediate subsurface flotation. The cable
between the surface buoy and intermediate
subsurface flotation is elastic. The other part
is profiling on a taut cable only attached to the
buoy it is a pendular cable.
In case of bad weather, the YOYO is not stuck
near the surface.
The description of the surface buoy was more
particularly developed in an other sheet.
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SENSORS
Appropriate sampling of physical,
biogeochemical, biological and optical processes
over a broad range of scales is a key requisite
to understand and model the carbon cycle
variability in the context of climate range.In
particular, repeated sampling of the upper ocean
where photosynthetic activity takes place is
essential. As a consequence, this project
involves some major technological challenges in
terms of development of novel sensors. So, the
main sensors are presented here
OPC sensor The initial mechanical integration of
the OPC (Optical Plankton Counter) on to the YOYO
body took place in Toulon in June 1999. The OPC
was attached to the YOYO body using a plastic
plaster piece.The aim of this mounting
arrangement is to position the OPC intake in a
relatively unperturbed flow of water as the YOYO
descends.
ANAIS sensor a sheet is specially dedicated to
this sensor
CTD sensor this sensor was test this year in
Casablanca and the results are available in the
sheet Casablanca oilrig test. Thanks to
numerous tests it works properly and it is ready
for the final test.
Others sensors Numerous sensors are present on
YOYO body during the field tests.There are light
sensors, PCO2, trace metal, fluorimeter and
transmissiometer sensors.
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THE ANAIS INSTRUMENT
The ANAIS instrument developed in the YOYO 2001
project is part of the new instrumentation
required for an autonomous in situ monitoring of
the Ocean. In order to measure the dissolved
macronutrients which are key elements in the
oceanic carbon cycle, an Autonomous Nutrient
Analyser In Situ (ANAIS) was developed. This
chemical analyser is autonomous and it is able to
measure simultaneously dissolved nitrates,
silicates and phosphates. Since autonomous
system capable to measure the macronutrients down
to 1000m is presently existing, the Yoyo/ANAIS
instrument can be considered as a first step to
an in situ multidisciplinary autonomous oceanic
observatories.
The ANAIS Instrument The components on the ANAIS
analyser are 3 chemical analyzers, an
equipressure container, a system for in situ
seawater sampling, a set of standards and
reagents bags, a 4-electronic cards set for
numerical recording and storage of processed data.
Silicates Analyser Phosphates Analyser
Nitrates Analyser
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BLANES TESTS
The subsurface profiler equipped with ANAIS and
CTD (FSI) was successfully tested from a
subsurface mooring deployed off Blanes (Costa
Brava, Spain) in october 1999.
The YOYO -ANAIS mooring was deployed in
autonomous conditions during 2 weeks.Two cycles
(profiles) per day were scheduled.
Numerous profiles of temperature and salinity
were collected between 200m and 1100m. As ANAIS
is a slow response sensor, YOYO was rising up
slowly at the proper speed 4cm/s in order to
obtain the required resolution. Profiles are
shown in this figure
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CASABLANCA TESTS-1998
Modifications, made to the vehicle part in order
to reach the surface and regulate its velocity as
required by the various sensors,have been
successfully tested from the Casablanca oil rig,
near Tarragona, Spain.
The profiler adapts its rising and descending
speed to the sampling strategy and the response
time of the various sensors. Here the rising
speed is about 0.06m/s and the descending speed
0.45m/s. This test with a single body Yoyo in
Casablanca also celebrated the adaptation of the
new acoustic system.
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CASABLANCA OILRIG TEST
The 2-body YOYO was tested in order to
check -the accuracy of the velocity regulation
during ascent and descent. -the acquisition
card developed by LODYC and data storage with
all sensors.
The YOYO completed 27 cycles of 3 hours
over 3 days. The mean ascent and descent
speeds were respectively 4.5cm/s and 40cm/s.
When the weather is too bad (pictures on the
right), YOYO was blocked at 40m under the sea
surface. This phenomenom is a good-effect
of the pendulum-like mooring the drag
component forces the YOYO to go down, this is the
way to avoid the YOYO being damaged at the
surface.It would not be the same if the YOYO
cable was fixed on the bottom.
Concerning data acquisition system, it has been
worked properly.
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LODYC/CNRS Paris France CoordinatorC.PROVOST CNR
S-LODYC Tour 14-15 4,Place Jussieu 75252 PARIS
CEDEX 5, France cp_at_lodyc.jussieu.fr

PARTNERS ?LODYC,Paris,France ?SOC,Southampton,UK ?
LEGOS,Toulouse,France ?IPG,Karlsruhe,Germany ?CEA
B,Blanes,Spain ?SME ECA,Toulon,France ?SI,Southsha
mpton,UK ?LIM/UPC,Barcelona,Spain