Tim McGinnis* Bruce M. Howe University of Washington Applied Physics Lab * ALOHA Observatory Moored Sensor Network with Adaptive Sampling

Introduction Overview Science Objectives/Opportunities Project Team User and System Requirements Preliminary Design System Description Major Components Sensor Suite Schedule Outstanding Issues

Overview – HOT Site Hawaii Ocean Time-series “HOT” Site –3 Stations: Kahe, Kaena & ALOHA –monthly cruises for 15 years –ALOHA Station 100km N of Oahu

HOT Science Mexican sub-mesoscale eddy (“Meddy”) Discovered on ship- based CTDO 2 cast at ALOHA 200m vertical extent in mid-water with no surface signature Extremely low O 2 and high salinity are unprecedented Water sample analysis showed that the highly anomalous waters were unambiguously from offshore Baja California Rare event (1 in 15 years) or were others missed due to intermittent sampling? From Lukas and Santiago-Mandujano, 2001

HOT Science Intermittant, cold abyssal overflow from Maui Deep to Kauai Deep These overflows cause large enhancement of diapycnal (nearly vertical) mixing with global impacts What forces these overflows? How should they be modeled? Is this “sloshing over the rim” and associated mixing common to deep ocean basins?

HOT Science Profiles from CTD cast at HOT site Large spikes in fluorescence (at 125, 134 & 141 dbars) are associated with steps and layers in density Did turbulent overturns homogenize the density in the layers with the suspended materials sinking to the bottom of the layer? To what degree do such optical signals correspond to turbulent overturning? How many similar cases are missed with monthly cruises & casts?

ALOHA Observatory Utilize a retired telecommunications cable and install observatory node at HOT site Originally planned to use analog coax ANZCAN cable – now plan to use optical HAW-4 cable (shown at left) Replace monthly cruises with combination of: - sustained in-situ observations (seafloor sensors, moorings, gliders, etc.) - several ship cruises per year (process oriented measurements)

Overview - ALOHA Observatory Mooring (AOM) Major Components –Seafloor sensor suite & junction box –Subsurface float at ~200m depth with sensor suite and junction box –Mooring profiler with sensor suite that can “dock” with the float for battery charging, data download and command upload –4500m electro-optical mooring cable Features –Cable connection provides high power and real-time communications –Enables adaptive sampling –ROV servicing and installation of sensors Deployments – on VENUS Observatory in Saanich Inlet, B.C. – on ALOHA Observatory at HOT Site, 100 nm N of Oahu

Project Team University of Washington, Applied Physics Lab Bruce Howe, PI, Principle Investigator Tim McGinnis, Co-PI, Electrical & System Engineering Jason Gobat, Co-PI, Mooring Design, Sensor Integration Jim Mercer, Co-PI, ALOHA Observatory Interface Vern Miller, Mechanical Engineering Chris Siani, Electrical Engineering Mike Kenney, Software Engineering Tim Wen, Software Engineering Janet Olsonbacker, website design University of Hawaii Roger Lukas, Co-PI, Data Management, Outreach University of Maine Emmanuel Boss, Co-PI, Optical Sensors & Data Analysis

System Engineering User Requirements System Requirements System Design

User Requirements Provide water column current profiling for entire water column Near continuous in-situ profiling from near surface to seafloor with CTDO, ACM, optics, Profiler rate of advance to allow 1 sampling cycle per tidal half cycle (6 hours) Profiler charging time (in dock) must be less than 6 hrs Profiler duty cycle must be greater than 90% Profiler sampling rate and profiling depth range must be controllable Provide extra Science User Connectors with “standard” power and data interface on float and seafloor Provide real-time, high bandwidth communication for Science User instruments

System Requirements Compatible with ALOHA power and data interfaces Power load on ALOHA must be constant power within +/- 10% Provide 12Vdc (?), 48Vdc and 400Vdc (?) power and 10/100BaseT communications at Science User Connectors Provide connection method for standard RS-232 sensors ROV serviceable j-boxes Operational life of > 2 years Located > 2 km from ALOHA node to allow ROV access to ALOHA node and instruments

Goals Provide video at Float and Seafloor J-boxes and on still camera Profiler Profiler mountable/removable by ROV Profiler rate of 40 cm/sec (standard is 25 cm/sec)

Block Diagram: ALOHA – Anchor J-box

Block Diagram: Float – Profiler

Junction Boxex – Float & Seafloor On Seafloor near Anchor & on Float 4 User Connectors Data Communications 10/100BaseT RS-232/422 (?) Power - ~200W total 400 Vdc (? no large or remote loads) 48 Vdc 12 Vdc (? probably more common) Installed Sensor Suite 2 x CTDO Optics – transmissometer, fluorometer, CDOM, other (?) ADCP (on Float) Video on Float and Seafloor (goal)

Junction Box – Float & Seafloor

Junction Boxes – Float & Seafloor Inherited from NEPTUNE/MARS development Node Controller hardware and software Shore power control and monitoring, archiving, GUI Load control – switching, over current, ground fault DC-DC converters ROV mateable connectors New Development Small Ethernet switch Ethernet – RS-232 conversion Ethernet electrical-optical conversion

Observatory – Instrument Interface Embedded Device Servers - 10/100BaseT Ethernet - Multiple RS-232 ports - Memory space for metadata/embedded website - TCP, UDP, SNMP, DHCP, etc. - Auxiliary I/O lines …….or could have multi-port serial hub in the J-Box and use serial through the User Science Connectors

Observatory – Instrument Interface Examples

Electrical-Optical Conversion ROV mateable electro-optical connectors very expensive (~$20k) and not likely to be used extensively on observatories for instrument connection ROV mateable electrical connectors are lower cost (~$2k) and will be used on MARS, VENUS and ALOHA Fiber optic cables are required for data transmission > 100m Transmission distances up to 100 km COTS ethernet electrical-optical converter available for operation in 10kpsi oil (~$2k)

Electrical-Optical Conversion Allows use of standard ROV connector with copper conductors for Ethernet communications over long distances Cost significantly less than E-O hybrid connector

McLane Mooring Profiler 6000m depth rating Trajectory and sampling schedule programmable pre-deployment Resistant to cable fouling 1 M meters of travel per battery charge Standard sensors CTD 4 axis Acoustic Current Meter (ACM) ~40 units sold

McLane Mooring Profiler Modifications New motor, gearbox, wheel re-design to fit larger EOM cable (~18mm) Mount 2nd CTD, optical sensors Interface AOM controller to their modem port to offload data after every profile Replace primary Li batteries with rechargeable Li-Ion Plan to use existing McLane housing Modify cable mounts & retainer for ROV servicing (goal) Profiling rate will be set by gearbox – not controllable – 25 cm/s (std), 40cm/s (goal) Need to decide on profiling and charging times (4 days/4 hours looks achievable with reasonable size battery packs.)

Float/Dock Configuration

Coupler Primary & Secondary

Seafloor Node

Float SIIM ROV serviceable using “fork lift”

Deployment Frame

Inductive Coupler Guide (attached to Float) Primary Core Compliant Mount Secondary Core Secondary Guide Charger Cable From S&K Engineering, Inc. Concerns: - biofouling - robustness - holding profiler in place during charging

Inductive Coupler Guide (attached to Float) Primary Core Secondary Core Guide Mooring cable Secondary Core Angled core interface From S&K Engineering, Inc.

Power Budget Estimate Seafloor J- Infrastructure 10 W Anchor Sensors 35 W Sediment Trap Mooring (K. Smith) 50 W Float Infrastructure 10 W Float Sensors 40 W Float Battery Trickle Charging 5 W Conversion and Transmission Loss 50 W ALOHA Supply200 W

Sensors Float - ADCP (w/tilt, heading ?) - CTDO – Dual - Transmissometer - CDOM - Other optics ? - Video/lights - Argos transmitter ? - Light ? - Acoustic Transponder ? - Engineering Sensors mooring cable load cell ? Anchor - CTDO – Dual w/precision depth - Transmissometer - CDOM - Other optics ? - Video/lights ? Profiler - Stock sensors CTDO – Dual ACM - Transmissometer - CDOM - Other optics ? - Video/still camera/lights ?

Schedule 03CY2004CY2005CY2006 Q4Q1Q2Q3Q4Q1Q2Q3Q4Q1Q2Q3Q4 Preliminary Design Design Review Detail Design Procure & Fabricate Assembly Shop Test Puget Sound Test VENUS Deployment VENUS Recovery Critical Design Review Final Procurement - Redesign ALOHA Deployment ALOHA Maintenance ALOHA Recovery (?)

Outstanding Issues Need ALOHA Interface specs Float depth of 200m – want to get below light (biology) & surface waves Fishbite protection on the mooring wire would add a layer to the cable and complicate profiler movement. Do we need it? Use “standard” Observatory ROV mateable connectors and instrument interface Need good precision survey of site – water depth of mooring site