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Stochastic Forecasting of Drifting Ships and Smaller Objects

Stochastic Forecasting of Drifting Ships and Smaller Objects. Dr Øyvind Breivik Norwegian Meteorological Institute Kjell Røang Christian Michelsen Research. Objective.

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Stochastic Forecasting of Drifting Ships and Smaller Objects

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  1. Stochastic Forecasting of Drifting Ships and Smaller Objects Dr Øyvind Breivik Norwegian Meteorological Institute Kjell Røang Christian Michelsen Research

  2. Objective • To generate search areas for the Norwegian Search and Rescue Service based on the best available wind and current information Challenge • Make search areas as small as possible, but not smaller

  3. Other uses • Containers • Mine-like objects • Objects at large (buoys, ROVs)

  4. The Uncertainties Involved • Where and when did the accident take place? • Which object should we look for (life raft, person in water, …)? • What are the wind conditions like in the area? • What are the surface currents in the area?

  5. Search Maths POS = POD x POC • POS: Probability of success (do we find what we are looking for?) • POD: Probability of detection (the keen eyes of the rescuers) • POC: Probability of containment (are we searching in the right place?), our business

  6. Forces on a Drifting Object • Wind (leeway) • Surface current • Wave motion (damping and excitation) The motion of an object of arbitrary shape is difficult to model, approximations are needed

  7. Leeway divergence • Leeway divergence sends objects at an angle relative to downwind • Symmetry allows stable drift left and right of downwind (little jibing is observed). →Diverging search areas with time

  8. Downwind Approximations Wind speed and object drift is approximately linearly related Different objects drift differently ... Undrogued life raft Life raft with drogue

  9. Crosswind

  10. Empirical leeway model

  11. Archive and prognoses 7 day archive combined with 60 h prognoses of • Wind from 20 km res. atmospheric model (HIRLAM 20) • Surface currents from 4 km res. ocean model with tides and wind forcing (POM)

  12. Wind and current close up

  13. AWI 0203

  14. Icelandic exercise 2003

  15. Faroe exercise 2004

  16. Operational use of LeeWay model • Service operational from 2002 • Simulation started by web order form • Result transferred by e-mail • Result presented in JRCC decision support system SARA

  17. System architecture Web order Result Presentation Wind and Current Drift Simulator E-mail Transport GRIB format

  18. Web order, old

  19. Web order, New

  20. Results, sailboat

  21. Results, PIW and Life raft

  22. Other simulators • Oil drift • Ship drift

  23. Web order oil drift simulations

  24. Oil drift

  25. Web order, ship drift simulations

  26. Ship drift, 1 simulation

  27. Ship drift, ensemble model

  28. Other services • Weather forecasts overlay (MetOc) • AIS/VMS • Weather Observations

  29. Weather forecast

  30. AIS Legend Graticule Basestations Ports

  31. Weather Observations

  32. Weather Observations

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