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RAPID-MOC Mooring Array Instrumentation

RAPID-MOC Mooring Array Instrumentation. Instrument types and specifications Telemetry. Instruments. CTD and current profilers (MMP and HOMER) Fixed point CTD (SBE 37 - microCAT) Current meters (S4) Tide gauges or bottom pressure recorders (SBE 26) Test instruments. How did we choose?.

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RAPID-MOC Mooring Array Instrumentation

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  1. RAPID-MOCMooring Array Instrumentation • Instrument types and specifications • Telemetry

  2. Instruments CTD and current profilers (MMP and HOMER) Fixed point CTD (SBE 37 - microCAT) Current meters (S4) Tide gauges or bottom pressure recorders (SBE 26) Test instruments

  3. How did we choose? • Satisfy the sensor specification and accuracy that we specified • Reliable • Robust • Simple to use

  4. The SBE 37-SM MicroCAT is a high-accuracy conductivity and temperature (pressure optional) recorder with internal battery and memory. Designed for moorings or other long duration, fixed-site deployments. SBE 37-SM Pump: The submersible pump comes on for 0.5s for each sample. This improves the conductivity response and flushes the old sample from the cell Water does not flow between samples allowing the anti-foul concentration to build up protecting the cell.

  5. SBE 37-SM Specification Battery capacity is 80,000 samples (9/hour for 1 year)

  6. The SBE 26 continuously integrates pressure samples to obtain water level measurements unaffected by wave action, and also independently burst-samples pressure at rates up to 4 Hz for wave amplitude calculation. Water level integration and wave burst sampling intervals and durations are programmable. The large memory permits frequent water level recording and highly detailed wave characterization. For example, with an 8M byte memory and optional lithium batteries, a 120-day deployment could include water level measurements every 15 minutes and 20-minute, 2 Hz wave-burst samples eight times a day. SBE 26 SEAGAUGE Wave & Tide Recorder

  7. SBE 26 SEAGAUGE Wave & Tide Recorder

  8. S4 Current Meter by InterOcean The S4 Electromagnetic Current Meter measures the voltage resulting from the motion of a conductor (water flow velocity) through a magnetic field according to Faraday's law of electromagnetic induction. Simply stated, Faraday's law defines the voltage produced in a conductor as the product of the speed of the conductor (water flow velocity) times the magnitude of the magnetic field times the length of the conductor. In the case of the S4, the conductor length is the effective path between the sensing electrodes. The magnetic field intensity is generated by a circular coil, internal to the S4, driven by a precisely regulated alternating current. The use of an alternating magnetic field and synchronous detection techniques to measure the voltage at the sensing electrodes provides an extremely stable, low noise current measurement. Two orthogonal pairs of electrodes and an internal flux gate compass provide the current vector.

  9. S4 Specification Current Speed ------------------------------------------------------------------------ Range 0-350 cm/sec (standard) 0-50, 0-100, 0-600, 0-750 cm/sec Accuracy: 2% of reading +/- 1 cm/sec Sampling Rate: S4/S4A S4AH 2 Hz 5 Hz Resolution: 2 Hz 0.03 to 0.35 cm/sec depending on range   5 Hz 0.037 to 0.43 cm/sec depending on range Noise: Less than the resolution for averages of 1 minute or longer 0.05 cm/sec rms for 10 second averages 0.25 cm/sec rms for 2 second averages 0.75 cm/sec rms for burst sampling (0.5 second rate) Threshold: Equal to resolution Vertical Response: True cosine response (internally software corrected with Tilt option) ------------------------------------------------------------------------ Direction ------------------------------------------------------------------------ Type: Flux-gate compass Range: 0-360 Resolution: 0.5 deg Accuracy: +/- 2 deg within tilt angles of 5 deg Tilt: +/- 4 deg for tilt angles between 15 and 25 deg

  10. Profiling CTD and current meters • HOMER • MMP

  11. HOMER • Bottom mounted package with a buoyant capsule and CTD that is winched through the water column • Max depth 3000m • Range 400 m from the bottom • Velocity of buoy 0.3 m/s • Capability: 1 profile per day for 1 year

  12. MMP • The McLane Moored Profiler (MMP) is an autonomous, instrumented platform. • Designed to provide long time-series, in situ profiles of temperature, salinity, velocity, and other quantities of interest. • The commercial version, the MMP MK 7, is now in production at McLane Research Laboratories, Inc. (MRL). • The new design incorporates the proven features of the original prototypes, developed by the Advanced Engineering Laboratory of the Woods Hole Oceanographic Institution, in a package that is easily serviced in the field and robustly tolerant of typical shipboard conditions. • An all new MK10 is in development for SOC with new sensors and an inductive modem for telemetry.

  13. Dimensions Height   130.5 cm Width   33.3 cm Length (body)   50.5 cm   Weight w/ Sensors (air)   70.5 Kg w/o Sensors (air)   64.3 Kg Max Depth   6,000 m Endurance   1Mm

  14. MK10 modifications for SOC • SBE41 CP - SeaBird CTD as used in argo floats • SBE44 Inductive modem for real time data telemetry • Main changes: longer body, larger pressure case

  15. Telemetry Developments by SOC • Specify new sensor and inductive system for MMP MK10 • mercury swivels for electrical connections • Surface buoy with rechargable batteries and solar cells • Iridium and Orbcomm transmitters/receivers

  16. Timescale • Persistor computer system with power controller and Iridium interface is built and under test. • SeaBird SIM and UIM components have been purchased and will be integrated with the Persistor once we know how the MMP is to control the data transfer. • A prototype buoy hull has been delivered together with frameworks for the solar panels and batteries. • The solar panels and batteries are under test. • A miniature GPS receiver has been purchased and tested. • Outstanding work: •  Integrate Orbcomm communicator into system and test with new short antenna. •  Build electronics housing and antenna platform and integrate into buoy. •  Integrate SIM board and test data transfer from (simulated) MMP back to SOC. •  Integrate GPS receiver and antenna. •  Build and test battery and temperature monitoring circuits and integrate. •  Fit pressure relief valve to buoy hull. • In early September it is planned to take the Persistor/Iridium/SIM subsystem to McLane in the States (September 8th 2003) to check that it communicates successfully with the MMP.

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