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OASIS :Ocean Acquisition System for Interdisciplinary Science

Figure 1. Machinist Lauren Mitchell in the high bay during a mooring buildup. The tower and instrument cages, along with other items, are made in MBARI’s machine shop. On the left are the 3 legged towers used on the equatorial Pacific mooring, on the right is the 4 legged M1 tower used in Monterey Bay.

Two OASIS moorings have been successfully deployed off the central California coast since 1992. Real-time access and 2-way telemetry has allowed the moorings to become test-beds for the deployment of new sensors, and widely used observational and planning tools. Over longer time scales the moorings will be an important tool for tracking environmental variability. OASIS drifters have been tested in 11 deployments off California and 3 deployments in the equatorial Pacific.

*Table 1. M3 and M4 are no longer deployed; these were deployed in 1999-2000.*
Mooring Name	Decimal Latitude	Decimal Longitude
M1	36.75	-122.03
M2	36.70	-122.39
M3*	36.57	-122.96
M4*	36.19	-122.45
S2	36.66	-122.37
S3	36.50	-122.93

For a description of the OASIS controller, its deployment on moorings and drifters see Real time experimental moorings:An OASIS in Monterey Bay, California

Figure 2. View of MBARI moorings, subsurface moorings, and telemetry.
Download map as tiff image (1mb)

Figure 5. A view of the instrumented mooring M2.

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Figure 3. Engineering view of Mooring 1 (M1) Click on the image for an enlarged view (12k)

Figure 4. Diagram of the OASIS controller. The controller is currently being redesigned. Click on image for an enlarged view.

Figure 6. Subsurface portion of the floatation platform. The lower section of the elevator shaft is visible with its suite of sensors. The elevator raises the sensors for easy access during in-situ maintenance.

Figure 7. Biofouling on the M2 mooring, the number one problem for the moorings. The moorings are pulled in on a regular basis for maintenance: rebuild, cleaning and replacing instruments. Routine maintenance is also done in situ, with technicians boarding the mooring while
out at sea. Routine maintenance includes replacement of the large battery packs that help power the instruments

Figure 8. Erecting the telemetry tower on Mount Toro. The advantages of two-way, real-time telemetry are several fold. It allows for quality control of data so as not to lose long, expensive mooring deployments. The data is immediately available for analysis, assimilation into models, and calibration of satellite sensors. The real-time information provided by the system can be of tactical use for shipboard experiments, especially those geared at episodic events. Finally, instruments can be accessed remotely so that sampling frequency can be modified according to needs or troubleshooting be performed without retrieval.

Figure 9. OASIS surface drifter, used in the 1995 Coastal Ocean Processes cruise, with subsurface instrument cage ready for deployment from the Point Sur. Sensor data and GPS position are sent by packet radio via Mount Toro to MBARI and the Point Sur.

Figure 10. Schematic of OASIS drifter (Hans Jannasch). The OASIS controller is supported in a donut-shaped flotation collar. GPS and packet radio antennas, a radio-pinger, strobe light and lifting-eye are the above-surface components; a sensor rack at 1.5 m supported a nitrate sensor, light scattering sensor (LSS) and fluorometer during the deployment. Beneath the sensor rack a 5 m bungie and slack safety cord connect the drifter to a 10 m long ‘holey sock’ or drogue, which reduces windage.

Table 2. Surface Mooring Configuration. *M3, M4 deployment 1999-2000. Mooring Data Archive
Device	Properties Measured	Platforms	Sensor Locations
Current Profiler (300,150, 75 khz ADCP)	Acoustic backscatter broadband, narrowband, long-ranger	M1, M2, M3*	Near surface (0-300, 8m bins)
CTD	Salinity, temperature, chlorophyll fluorescence, optical clarity	M1, M2, M3* Drifters	Near surface
ECO FL	Fluorescence, turbidity	M1	Near surface
ECO BB	Backscatter	M1	Near surface
ASIMET HRH	Relative humidity/air temperature	M1	Near surface
ASIMET LWR	Longwave Radiation	M1	Near surface
ASIMET SWR	Shortwave Radiation	M1	Near surface
HydroScat (HS2)	Backscatter	M1, M2	Near surface
HydroRad (HR2, HR3, HR4)	Multichannel hyperspectral radiometer	M1	Near surface
MicroCat Thermistor String	Temperature, Conductivity (10 depths )	M1, M2, M3*	0, 10, 20, 40, 60, 80, 100, 150, 200, 250, 300m
MetSys	Relative air humidity, air temperature, wind speed and direction, barometric pressure	M1, M2, M3*	Air
GPS	Latitude, longitude	M1, M2, M3*, Drifters	Air
CO₂ Analyzer (LI 6252)	Carbon dioxide	M1, M2, M3*	Air, near surface
Spectroradiometer (PRR, Satlantic)	Upwelling radiance, Downwelling irradiance, PAR, MCP* (downwelling at 490nm), Fluorescence, Temperature, Depth* (* @ 20m)	M1, M2	0m, 20 m
Nitrate ISUS	Nitrate	M1, M2, Drifters	Near surface
Echo sounder	Bottom depth	M1, M2	0m
Battery, temperature, pressure	Voltage, temperature, pressure	M1, M2, M3*, Drifters	Inside OASIS controller can
OASIS	Data acquisition, telemetry	M1, M2, M3*, Drifters	----
Packet Radio	Telemetry	M1, M2, M3*, Drifters	----
Oxygen Sensor	Oxygen, conductivity, temperature	Drifters	Near surface
Light Scattering Sensor (LSS)	Optical backscatter	Drifters	Near surface
Fluorometer (WetStar)	Chlorophyll fluorescence	M1, M2, Drifters	Near surface

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Last Updated: 29 April, 2004