1. OC3570 Cruise Project Presentation: Slocum Glider Study
Presented by
LT Kim Freitas
11 March 2008

2. Purpose of Experiment Importance to the Navy
To learn the operational characteristics of the Slocum glider
To explore the quality of the data gathered by the glider
To analyze the oceanography data collected by the glider and draw some basic conclusions from the data
Understanding the ocean environment to exploit tactical advantages
Understanding the glider data in order to best ingest it into models
Importance to the Navy

3. Glider Basics Specifications Weight: 52 Kg
Hull Diameter: cm
Vehicle Length: 1.5 meters
Depth Range: meters
Speed, projected: 0.4 m/sec horizontal
Energy: Alkaline Batteries
Endurance:[ Dependent on measurement and communication type] 30 days
Range: 1500 km
Navigation: GPS, and internal dead reckoning, altimeter
Sensor Package: Conductivity, Temperature, Depth
Communications: RF modem, Iridium satellite, ARGOS, Telesonar modem
Courtesy of Webb Research

4. Glider in Motion Click for video
Courtesy of Rutgers University, YouTube, and Peter Guest

5. Experiment Layout Glider deployed near eastern waypoint
Diving profile – to 200m at constant angle (26º), then back to surface
Collecting scientific data on the downcast
Once reaches western waypoint, turn around for waypoint one
Expected to take 2 trips per day

6. Glider’s Actual Track
Due to stormy conditions, glider was set off its track
It tried to return to waypoints, but could not overcome the current
Ended up abandoning mission
From Cruise Log: Glider89 (deploy) / 0055 Glider89 (recover) / 1619

7. Data Manipulation
When the glider abandoned its mission, it “parked” – parked data not included
Of 90k+ data points, about 2/3 unusable due to NaN observations
Turbidity, fluorescence, conductivity – still some NaNs due to different sampling frequency

8. Lessons Learned Before the Data Analysis
Not enough self-generated momentum
Probably not ideal for cross-current studies, especially during storms
Best to set glider to collect on downcast AND upcast
Is there a better way to “tune” the scientific package for better data (fewer NaNs)?

9. Temperature
(ºC)

10. Salinity
(psu)

11. Sound Speed

12. Density
(kg/m3)

13. Temperature-Salinity Plot

14. Data Binned by Depth
Majority of the variability was contained in 30-80m of water
No clear separation of hi/lo temp variability by further binning

15. Data Binned by Distance
Low temp in first 6km
Low-high transition in second 6km
High-median transition in third
Little variability for rest of mission
Suggests variability in time – calm weather at first followed by onset of storm

16. Temperature-Salinity-Depth
Both the high temp pocket and the low temp pocket are in the 30-80m range
Deeper water much more “normal”

17. Salinity Variability at 50m
50m sample representative of the TS variable water
High salinity, drops to low salinity, transitions to mid then low

18. Discussion/Conclusion
Learned some features of the glider and how to better set the scientific package
Quality of the data collected – not the best, but we have some ideas for how to make it better on future deployments
Oceanographic data indicates highly variable layer from 30-80m – perhaps some spatial water mass features
Discovered what data results from the glider use, a better mission plan, and how to use that data to understand the environment

19. Questions?