Simultaneously Improving Glider Position Estimates and Ocean State Forecasts OASIS, Inc., Patrick Cross, (808) 423-0011, [email protected]$404,649 Short term goals: develop and test an iterative method for improved subsurface position estimates for ocean gliders Long term goal: integrate method with Navy 4D-Var ocean model data assimilation Content of Presentation Penta Chart: New method for position estimates Importance – ocean models, raw interpretation State of the Art – Linear dead reckoning, introduces errors in ocean state calculations/forecasts Customer – Naval Oceanographic Office, IOOS Project Plan and Timeline Quantitative Goals and Success Criteria Work Tasks/Costs/Level of Effort Customer engagement plan 1
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Simultaneously Improving Glider Position
Estimates and Ocean State ForecastsOASIS, Inc., Patrick Cross, (808) 423-0011, [email protected]
$404,649
Short term goals: develop and test an iterative method for improved subsurface
position estimates for ocean gliders
Long term goal: integrate method with Navy 4D-Var ocean model data assimilation
Content of Presentation Penta Chart: New method for position estimates Importance – ocean models, raw interpretation State of the Art – Linear dead reckoning, introduces
errors in ocean state calculations/forecasts Customer – Naval Oceanographic Office, IOOS Project Plan and Timeline
Quantitative Goals and Success Criteria Work Tasks/Costs/Level of Effort Customer engagement plan Project Plan and Schedule Transition plan
Questions/Discussion and backup slides1
2
• Improvements in NAVO support capabilities for ASW, MIW, NSW
• Improved interpretation of raw glider data
• Improved ocean model forecasts
Developing a Method to Improve the Accuracy of Glider Subsurface Position Estimates
• Take advantage of state-of-the-art ocean models
• Develop glider kinematic model guided by ocean model
• Input glider data into ocean model at improved positions
Glider data is increasingly prevalent. Improved positional data will greatly enhance its utility.
MAIN ACHIEVEMENTS (Expected)• Develop glider kinematic model
• Develop statistics relating to scale of positional issue by leveraging ONR field test in Phil Sea
• Develop iterative technique, using high-res ocean model, to improve subsurface position estimates
• Field test method in Hawaii using bottom transponders for accurate measured positions
HOW IT WORKS: • Kinematic model incorporates vehicle inertial
• Glider model takes output of ocean model, over time, to predict x, y, and z coordinates of glider position through course of dive
• Glider data (T/S) is input back into ocean model at improved positions
• Process is run iteratively to seek convergence and improved ocean state forecasts
ASSUMPTIONS AND LIMITATIONS:
• Scale of possible positional improvement must exceed grid resolution of ocean model
• Possibility that solution may not converge
• Field validation very important to project
• Gliders in use by Navy and others in growing numbers
• Position during dive based on linear dead reckoning only
• Glider kinematic model
• Iterative technique developed
• Field test in Hawaii
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Improved Underwater Glider Positions
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Company: OASIS, Inc. Contact: Patrick Cross Email: [email protected] Phone: (808) 423-0011
~ 2.5 km
~ 7.5 km
Transponders
Intended glider flight path
Importance Navy is committed to large fleet of ocean gliders (100 or more) through Littoral Battlespace
Sensing, Fusion, and Integration (LBSFI) program
Characterization of Battlespace for ASW, MIW, NSW, EOD applications
Feed broad area ocean models
Glider fleet managed by Naval Oceanographic Office (NAVO)
Glider data is used in raw form and ingested into predictive ocean models, such as NAVO’s
Navy Coastal Ocean Model (NCOM)
Gliders obtain GPS fix when on surface, but position is not known accurately once they dive
Can lead to errors in estimation of ocean state, and, when assimilated into an ocean model, errors
in forecast fields
Our concept of using an ocean model, paired with a glider motion model, to provide
enhanced subsurface glider positional accuracy is supported by NAVO (Dr. Frank Bub and
Mr. James Rigney). Also, PMW-120 (Dr. Ed Mozley) has expressed interest in the method
and would pick up funding beyond CEROS as part of LBSFI program.
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State of the Art(no effort here yet)
Describe the state of the art and the state of the practice
Identify other individuals and research groups who are working on
the problem (including alternative approaches)
Describe the ways in which your project will advance current
knowledge and practice
Describe the technical challenges
Additional detail slide (or two… mindful of existing content already
submitted in your written proposal, and time limits on presentation!)
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Advancing the State-of-the-Art
Ocean Model(such as NCOM)
VelocityField
Estimated gliderx, y, z vs time
Glider Model
Assign glider T/Sto revised x, y, z
considers vehicle inertial
mass, surface area, drag
coefficients, seawater
density, vehicle lift and drag
Crude effort atblock diagram
Customer – Naval Oceanographic Office (NAVO)
Project endorsements
Dr. Frank Bub, NAVO Ocean Modeling Technical Lead – interested and pressing endorsement
through CNMOC Advisory Board
Mr. James Rigney, NAVO Chief Scientist – “potentially useful to NAVO”, says CNMOC will
formally endorse
Dr. Ed Mozley, PMW-120 Asst. Program Manager – willingness to fund follow-on work through
LBSFI
Envisioned nature of customer relationships:
Short term: Provision of NCOM model output, Guidance relating to method development
Long term: Operational implementation of method in NAVO Reachback Cell
Other sources of support, or related efforts:
Leveraging SPAWAR PMW-120 EMPath project (part of LBSFI)
Leveraging ONR Code 32 Deep Water Acoustics Philippine Sea 2010 test
Methodology will have benefits in ocean and climate modeling in academia, at NOAA
(IOOS Program), and elsewhere
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Methodology Develop glider kinematic model Run glider model during ONR Philippine Sea test
Test will span ~5 months of Seaglider deployments Glider model fed with output from NAVO’s NCOM Actual surfacing positions compared with those forecast by glider model to generate
statistics to assess degree of potential positional error
Develop ocean model iterative technique Utilize high-resolution UH ROMS model
Test iterative approach during Hawaii sea test ~ 2 weeks duration off leeward Oahu Utilize field of 8 bottom transponders 1000m dives, through transponder field Compare measured and predicted