The
M3A was designed as an open-ocean monitoring system
that can provide continuous information for physical
and bio-chemical parameters in the upper thermocline
and air-sea interaction parameters at the
sea-surface level. The overall concept of the system
follows the experience of the TAO - TRITON arrays of
the equatorial pacific, but makes a step forward
with the introduction of bio-chemical measurements.
The value of such measurements has already been
demonstrated in the Bermuda TestBed Mooring program.
The parameters to be measured are grouped in three
categories:
A.
Physical Parameters in the upper 500m of the ocean,
namely:
-
Temperature
& Salinity at: -1, -30, -50, -75, -100,
-150, -250, -350, -500m
-
Current
speed and Direction: 0-500m with aprox. 30m
spacing
B.
Bio-chemical parameters in the upper 100m of the
ocean, namely:
-
Dissolved
Oxygen, Chlorophyll, PAR, Turbidity at:
-30, -50, -75, -100m
-
Nutrients
(Nitrate) at -75m
C.
Air-Sea interaction parameters at sea surface, namely:
-
Air
temperature, wind speed and direction, air
pressure, relative humidity, wave height and
direction
Due
to the different measuring methods and sensor
technologies, the measuring devices for group B
(bio-chemical) parameters need a higher maintenance
frequency than the instruments of groups A
and C. For this reason, a configuration of
independent moorings was chosen. The line that hosts
the surface buoy (mooring #1) is considered as the
"master" system and has the control of the
"peripheral" systems (moorings #2 and #3)
and the responsibility of data storage and
transmission. Line #1 is also hosting the
meteorological instruments attached on the surface
buoy, the near surface instruments (-1m) that are
easily accessed for maintenance and the "deep"
instruments (150-500m) that have a low maintenance
frequency requirement.
Mooring
#2 is hosting the instruments that carry the
bio-chemical ("green") sensors that
require frequent maintenance, plus the physical
sensors at the respective depths (30-100m). This
mooring line has an autonomous data logger and an
acoustic modem for real-time data transmission to
the central unit in the surface buoy.
A third line (mooring #3) will host the ADCP at 500m, performing current
measurements up to surface.
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