dr Øyvind breivik norwegian meteorological institute · 2005. 4. 5. · generously made available...

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Norwegian Meteorological Institute Forecasting Drifting Objects Dr Øyvind Breivik Norwegian Meteorological Institute

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Page 1: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Forecasting Drifting Objects

Dr Øyvind BreivikNorwegian Meteorological Institute

Page 2: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Objective• To generate search areas for the Norwegian

Search and Rescue Service based on thebest available wind and current information

To paraphrase Einstein:• Make search areas as small as possible, but

not smaller

Challenge

Page 3: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

The Uncertainties Involved

• Where and when did the accident takeplace?

• Which object should we look for (life raft,person in water, …)?

• What are the wind conditions like in thearea?

• What are the surface currents in the area?

Page 4: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Search Maths

POS = POD x POC

• POS: Probability of success (do we findwhat we are looking for?)

• POD: Probability of detection (the keeneyes of the rescuers)

• POC: Probability of containment (are wesearching in the right place?), our business

Page 5: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Forces on a Drifting Object

• Wind (leeway)• Surface current• Wave motion (damping and excitation)

The motion of an object of arbitrary shape isextremely difficult to model, thusapproximations are needed

Page 6: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Empirical leeway data• 63 classes of SAR objects have been

compiled by the U.S. Coast Guard throughextensive field campaigns and weregenerously made available to the project.

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Page 7: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

ApproximationsApproximations

Wind speed and object drift is approximatelylinearly relatedDifferent objects drift differently

Life raft with drogue

Undrogued life raft

Page 8: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Wind to Wind to

WindDirection

From

WindDirection

From

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Wind to

Lα = -25o Lα = +25o

RWD = -135o RWD = +135o

Leeway DriftDirection

Leeway DriftDirection

Leeway divergence

• Objects drift at anangle to the wind (theleeway divergenceangle)

• Symmetry allowsstable drift left andright of downwind.

• This leads to adiverging search areaas time progresses

Page 9: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Forcing• Wind from 20 km res. atmospheric model (HIRLAM 20)• Surface currents from 4 km res. ocean model with tides and wind forcing (POM)• Archived winds and currents go 7 days back – forecasts up to +60 h

Page 10: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Search areas and ensemble modelling

A search area is foundby computing anensemble oftrajectories withslight changes in

• drift properties• wind field• initial position &

time of incident

Individualtrajectory

Page 11: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

leewayleeway.met..met.nono

•• SearchSearch area area simulationssimulationsare orderedare ordered via via the the webweb

•• Results areResults are returnedreturned to to the theRescueRescue Co- Co-ordinationordinationCentresCentres and and presentedpresented as asaa layer on layer on an an electronicelectronicsea chartsea chart

Page 12: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Bjarne – RCC test dummy

• Regular exercises • Daily tests

Page 13: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological InstituteIcelandic exercise 2003

Page 14: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Liferaft release positionLiferaft release position

Liferaft Liferaft pickup +16hpickup +16h

Ensemble search area (10nm x 10nm)

Manual Manual search search areasareas

Faroe exercise May 4th 2004

Page 15: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

•• RedoRedo older older leeway categories with new field methods leeway categories with new field methods•• Refine the taxonomyRefine the taxonomy for for different different parts parts of the of the world – in world – in

close collaboration with RCCsclose collaboration with RCCs

The flora of SAR objects

Page 16: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Fedje – a potential testbed

••Three Three HF radarsHF radars•• currentscurrents•• wave measurementswave measurements

••Weather stationWeather station••8 km 8 km wave modelwave model••4 km 4 km ocean modelocean model••Drifters (IMR)Drifters (IMR)

Page 17: Dr Øyvind Breivik Norwegian Meteorological Institute · 2005. 4. 5. · generously made available to the project. Aanderaa Current Meter Survival Suit 6 foot mannequin GPS/ARGOS

Norwegian Meteorological Institute

Conclusions & outlook• The model yields realistic search areas, but

further model evaluation is needed (morefield campaigns) to thoroughly assess itsforecasts capabilities for specific S&Robjects

• More leeway categories are needed to coverthe range of typical S&R objects found inNorwegian and European waters

• Error model for estimating uncertainties inwinds and currents should be improved