2. Acoustic Seaglider Results from Summer 2006 Bruce M. Howe Applied Physics Laboratory University of Washington ONR CODE 32 NW REGIONAL PROGRESS REVIEW Applied Physics Laboratory, University of Washington 27 February – 1 March 2007 Seattle, WA

3. Goals and Outline Develop and demonstrate the acoustic Seaglider in the persistent surveillance context: –As a communications gateway between subsurface platforms and land –To act as a general purpose acoustic receiver/tactical sensor for all signals and “noise”, with near-real time reporting of processed results –To provide oceanographic data Review results from 3 field experiments Discuss next steps

4. Acoustic Seaglider ½ knot at ½ W Up to 1000 m dives > 6 months, 3000 km, 600 dives Temperature, salinity and others Now with hydrophone and acoustic modem Fumin Zhang

5. Philippine Sea Kauai Monterey Bay Acoustic Seaglider Operations – Summer 2006 Philippine Sea – SG022, 7/29/06-7/30/06, 1 day, 15 dives, low ARS band,CTD Monterey Bay – SG022, 8/15/06-8/21/06, 6 days, 61 dives, low ARS band,CTD SG023, 8/18/06-8/23/06, 5 days, 83 dives, low ARS band, CTD SG106, 8/12/06-8/18/06, 6 days, 131 dives, high + low ARS bands,CTD,  modem Kauai - SG023, 8/31/06-10/8/06, 39 days, 143 dives, low ARS band, CTD

6. Monterey Bay 06: Positions where SG106 read  modem FSK packets Black circles: SG106 at surface after dive - no acomms received Blue circles: dives where acomms commands logged 106 sent FSK command to turn off the ARL-UT array Most FSK came from ARL- UT or Gateway Black +: dives after recording acomms logs ceased 4-5 km ranges are evident First FSK packet at 2006.08.15:0857 (UTC) from unit ARL-UT to Gateway, Dive 22. 1 km ARL-UT bottom node Gateway Kelp Array Latitude

7. MB06: RXD receptions vs range and depth Histograms of depths for RXD receptions Counts 0 10 20 30 40 0 50 100 depth(m) 0 20 40 60 80 100 120 140 depth (m) Counts 0 20 40 60 SG106 descending SG106 ascending Depth 0 m 100 m 5 km0 kmRange

8. 10 20 10 20 Time (s) 30 25 20 15 10 5 Freq (kHz) Modem performance: 1 st 30 sec of dive 41 30 PSD @ 8-10 sec 0 5 10 15 20 25 30 35 kHz Simple ACOMMS detector: ratio of energy in 23-27 kHz band to energy in 15-19 kHz band glider pump noise ACOMMS band – 23-27kHz Reference band – 15-19kHz { telling kelp to talk to GB from kelp to GB telling UT-VS to talk to GB Missed packet 21:24:14 UTC

9. Frequency Time (s)150 ~10 nm from ship Dive 13, file 2 0 Distant source Ship source, harmonics and reverb Signals Example of Lubell source recorded at SG023 (dive 20 segment 2) LWAD MB06

10. NPAL / ATOC Kauai source 260 W M-sequence coded signals 75 Hz, 35 Hz bandwidth 28 ms peak 27.28 s period 2 hour transmissions, 1 per day DIVE 56 -example 30 79 Red segments = ARS recordings

11. 10.8 ms } 14.7 ms } 13.0 ms } } 1/75 Hz = 13.3 ms Example time series Example PSD zoom PSD Kauai example

12. Motion and Coherent gain Doppler + stack: from 35 to 44 dB 9 dB of gain vs theoretical gain 14 dB Variation during 12 minutes Time – 12 minutes Relative travel time – 0.4 s Relative travel time – 0.16 s Relative travel time – 0.4 s Time – 12 minutes Doppler Arrival times (72.7195) (72.282) (72.8654) (72.9153) (73.4143) Single block 27.28 s Peaks shift due to changing s/r range Measured travel time changes ~3.7 ms per block Match glider kinematics 0.204 m/s, 136 m horizontal, 33 m vertical, 12 minutes

13. humpback 3 rd harmonic ~48 Hz 1 st harmonic ~16 Hz Blue whale ‘B’ call Blue whale ‘D’ call Humpback (very close) Blue whale Sea lions? birds Humpback @ 15 and 65 sec Blue @ 35 sec Sea Lions? @ 50 sec Animal sounds recorded on Seaglider ARS Monterey Bay, MB06

14. Ambient noise levels compared to Wenz

15. ASG – Summer 2006 Summary Demonstrated gateway capability – connecting subsurface platforms to shore via acoustic modem/satellite Iridium Demonstrated acoustic receiver – man-made signals, whales, noise… with near-real time processed results Potential – general ocean acoustics tool, tactical sensors, navigation/time node, data truck, marine mammal observing, tomography receiver, basin-scale thermometry, climate change, …

16. Next steps Fall 07 – PLUSNet07 off La Jolla –Spring/summer – mini PLUSNet in Puget Sound + scouting mission off La Jolla PLUS - Continuing development and field work –Communications: Modem integration and HFGW –Nexgen glider (payload, buoyancy, processing, …), –Tactical sensors – add directivity and gain Mission management –Optimization: High currents, power, multiple gliders –Navigation and timing –Overall situational awareness Integrating acoustics + nav into data assimilation – mobile acoustic tomography receiver

17. Related Projects ONR Philippine Sea 2009 – Ocean acoustics deep water, QPE DRI (many) NASA: A Smart Sensor Web for Ocean Observation (APL, EE, JPL) NSF STC Coastal Margin Observation and Prediction (OHSU, OSU, UW) NSF ORION …

18. Many helped! Geoff Shilling Jason Gobat Craig Lee Russ Light Pete Sabin Rex Andrew Keith van Thiel Keith Magness Troy Swanson Tim McGinnis Mike Boyd Kate Stafford Sue Moore Robert Miyamoto Marc Stewart Jim Luby Neil Bogue Andrew White Jim Mercer Linda Buck Joe Wigton Fritz Stahr and the Seaglider Fabrication Center Lee Freitag and Matt Grund Tom Hoover, Jim Bellingham, et al Joe Curcio and the MIT kayaks Clay Spikes, Dave Porter, et al Yi Chao Pierre Lermusiaux ONR sponsorship Skip Denny and the ANTS crew

19. Thank you Questions?

20. Backup/Extras

21. Glider – Kayak interactions in Monterey Bay Kayaks pinging to glider Graphs by Alexander Bahr MIT Computer Science & Artificial Intelligence Laboratory

22. Monterey Bay MB06 SG023 was allowed to drift on the surface for 2 extended periods during MB06 The resulting drifts were compared to surface current predictions from the HOPS model Leg 83 Current shear event experienced by glider but not captured by model forecast nowcast Leg 25

23. Temperature, salinity, conductivity data usually available within 5 min of dive completion – example SG023 dive 46 Dive 46 temperature and salinity as plotted on IOP website

24. recovered Drift 2 Drift 1 78 80 SG023 surface drifts Dives 55 and 83 followed by surface drift tests Data compared to current prediction models Drift 2 shows a current shear event

25. MB06 Acoustic Seaglider Accomplishments Deploy and operate sensors in field –428+ hours of dive time –300+ dives (acomms, T, S, Depth, acoustics, surface currents, depth-avg currents) Demonstrated Seaglider communications gateway capability –In-air – Iridium satellite –Sub-sea – acoustic modem at various depths and ranges –Passing NAFCON orders to remote kayak to prosecute target detected/reported by other kayaks (node of LBL navigation) –Turned bottom vector sensor array node on/off Ambient sound –Active source emissions - Lubell source (for TL, propagation) –Marine mammals (blues, humpbacks, sea lions, …) –Ambient noise budget (ships, seismics, wind, rain, …) Environmental data –Temperature and salinity into Harvard and JPL models –Depth averaged and surface currents –Bottom resting mode –Adaptive sampling

26. Coherent processing of M-sequence coded signals Arrival times (72.7195) (72.282) (72.8654) (72.9153) (73.4143) Peaks in each block shift due to changing s/r range Measured travel time changes ~3.7 ms per 27.28 s block Match glider kinematics 0.0204 m/s, 136 m horizontally, 33 m vertically, in 12 minutes Relative travel time – 27.28 s Relative travel time – 0.3 s Relative travel time – 0.4 s