Project Deliverable D50 Report on Best Practices ... - ESONET NoE

Table 2: Generic ESONET variables in the water column and at the seafloor surface.
Variable Geosciences Physical Biogeochemistry Marine
Oceanography
Ecology
Temperature X X X X
Conductivity X X X X
Pressure X X X X
Dissolved O2 X X X X
Turbidity X X X X
Ocean currents X X X X
Passive acoustics X X
Table3: ESONET Sensor requirements (Please indicate if these need revision).
Type of sensor Range Accuracy Sampling frequency
Conductivity 0 to 9 S/m 0.001 S/m 4 Hz*
Temperature -5 to +35°C 0.01 K 4 Hz*
Pressure 0 to 600 bar 0.1 % FSR 4 Hz*
Dissolved oxygen 0 to 500μM 5% 0.01 Hz
Turbidity 0 to 150 NTU 10% 1 Hz
Currents 0 to 2 m/s 2% 1 Hz*
Passive acoustics 50 - 180 dB re 1 μPa +/-3dB 96 KHz
* high-frequency only needed for a few applications (i.e. those related to turbulence)
These generic sensors scan be used to directly address a wide range of geo-hazard warning
and scientific applications related to understanding natural and anthropogenic variation and
the possible impacts of climate change. The generic systems will also provide supporting data
to a number of other users. Firstly these systems will be able to detect passing tsunami waves
and associated low frequency sounds related to earth motions. In the observatory setting these
data can then be relayed back to shore via seafloor cable satellite telemetry within minutes.
Because nearly all tide gauges are along shorelines, offshore data can improve warning time.
The system will be able to detect storm and tide wave loading, sedimentation dynamics that
influence turbidity such as resuspension, and benthic boundary layer (BBL) dynamics. By
linking the tide, turbidity, and current meter readings the interaction strengths and thresholds
for resuspension and sediment transport can be further described. Furthermore determination
of these parameters at the seabed and in the water column can help determine how seabed
processes interact with ocean circulation, biogeochemistry, and ecological parameters.
Combining the generic sensors with specific sensors such as seismometers, geodesy, bubble
flux observing systems, hydrothermal flow meters and piezometers the remaining key
questions outlined in <strong>Deliverable</strong> 11 can be addressed. These questions include; how are
seismic activity, fluid pore chemistry and pressure, and gas-hydrate stability, and slope failure
related? And, what are the feedbacks between deformation, volcanism, seismic, and
hydrothermal activity?
The generic sensors can address fully the questions related to physical oceanography.
However, a generic sensor module at the surface, midwater and/or at the seafloor can only
answer these questions partially. The use of salinity and conductivity sensors spaced regularly
along strings and additional ADCP coverage can, however, fully capture the themes related to
ocean physics. These include understanding wind driven and deep-ocean circulation,
planetary waves, and interactions between the BBL and seabed. Mobile systems used in
conjunction with the fixed infrastructures can also augment the impact of the generic sensors.
<strong>Deliverable</strong> #50 - update October 2010 18