1. Ocean Instrumentation
Luis Rodriguez
USNA Hendrix Lab

2. What is an Ocean Instrument
An instrument is used to describe characteristics within its environment and outputs a repeatable and understandable quantity
Components:
Sensor - A material that reacts to changes within its physical properties in a known manner when is in contact with the environment
Translator - converts signal into a usable form.
Micro-computer.
Display
Characteristics: Usually found in specs sheet
Sensitivity – How fast does it react to environment
Accuracy – Reproduce same quantity over time
Sampling Rate – ie. 4 Hz = 4 samples per second

3. What is an ocean instrument
Analog vs Digital instruments:
Thermometer vs Thermistor
Refractometer vs Conductivity sensor
Secchi Disk vs Profiling Natural Fluorometer (PNF)

4. Material properties Electrical – Conductivity
Calibrations – Changes in properties due to wear
Post Processing – Error due to pitch or heave
Mechanical - Stress / Pressure
Thermal - Temperature
Chemical - Change in color
Cl −
Cl −
Cl −
Na +
Cl −
Na +
Na +
Na +
Cl −
Cl −
Cl −
Cl −
Na +
Na +
Na +
Na +

5. Oceanographic Instruments

6. Oceanographic Vessels
YP-686 (100 Ft)
USNA Edgewaters (18 Ft)
Deep Water
Winch
Lab Space
Low draft for shallow applications

7. Refractometer
Water Sampler
Bucket Thermometer

8. CTD Conductivity Temperature Depth
Most basic oceanographic measurement
Usually installed on most oceanographic instruments
Density
Sound Propagation
Three main configurations:

9. Cage CTD Deep water applications with small vessel
Components Included:
Conductivity/Temperature Sensor
Pressure Sensor
PH Sensor
Dissolve Oxygen Sensor
Pump
Data logger / Brain Housing
Deck unit

10. Rosette CTD Collects live water quality data and discrete samples
Used for deep water applications with a winched vessel
Components Included:
Conductivity/Temperature Sensor
Water sampler/sensor interface
Pressure Sensor
PH Sensor
Dissolve Oxygen Sensor
Pump
Data logger / Brain Housing
Deck unit

11. CTD Sonde
Portable
Field Interchangeable Sensors
Long term deployments

12. Secchi Disk
Correlates the visibility of the disk from surface to the Euphotic depth.
(Multiply by 1.7)
Named after Angelo Secchi
(Friends with Commander Maury)

13. Profiler Natural Fluorometer (PNF)
PAR (Photosynthetic Available Radiance) sensor measures visible light penetrating the water column
Euphotic layer is where PAR is reduced to 1% of its surface value

14. Benchtop Fluorometer
Measures Chlorophyll A by continuous flow or discrete sampling

15. Acoustic Doppler Current Profiler (ADCP)
Down looking Workhorse ADCP on YP-686
Side looking ADCP
River Ray ADCP

16. Side-Scan Sonar Towfish
Maps the bottom bathymetry of the seafloor through ultrasonic pins
Maps up to 300m deep with a swath of up to 200m each side at 900kHz

17. Sub-Bottom Profiler Measures sediment composition through SONAR
Can measure into a 100m of sediment in up to 300m water depth

18. Ponar Sediment Grab

19. Plankton Net
Otter Trawl

20. Automated Underwater Vehicle (AUV)
Pre-programmable Missions
Able perform multiple samples over short amount of time
Expensive
Risk of equipment loss

21. Instrument Deployment
Techniques to use instruments:
Slow is good
Uniformness
Control Sample
Be safe