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‘Drifting’ buoy data - their effect on
‘Weather’ Analysis and ForecastingIan Hunter S A Weather Service 29/7/2002
Louis Vermaak – DBCP XVIII – Martinique 14-18 October 2002
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South African Weather Service (SAWS)
METAREA VII
• Our marine environment
• ‘Fixed platform’ in situ observation sites
• Remotely-sensed marine data
• SAWS marine products/ activities
• Drifters and some case studies
• Comments
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SAWS – our Marine Environment
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Tropical cyclone ‘Eline’ 22 February 2000
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‘Magdalena Oldendorff’ – icebound in METAREA VII
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Explosive cyclogenesis south-west of Cape Town
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Cut-off low generating heavy SE’ly swell
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Heavy SW’ly swell arrives at ‘The Dungeon’ south of Cape Town
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Courtesy OSIS Cape Town
Warm Agulhas Current water penetrating the South Atlantic
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10% + of world’s seaborne oil trafficrounds the Cape….
Courtesy : MRG Munich
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SAWS – our “Fixed Platforms”
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Courtesy MRG Munich
cf FA Platform central Agulhas Bank
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A visitor to Marion Is (48° S) – March 2002
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Bouvet Is. Norwegian AWS v. important for wave forecast models
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SAWS AWS on South Thule, South Sandwich Islands
- see ‘ship wave’ clouds, top left.
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Remotely-sensed Marine Data
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NOAA AVHRR data – Agulhas Current – 5 knots +
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MODUS – Terra – Gulf Stream
even higher resolution ...
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Scatterometer winds ex QUICKSCAT – not always available
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QUICKSCAT sees the pack ice – June 2002
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SAWS – our Marine Products/ Activities
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SAWS Global Spectral Model (GSM)
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SAWS regional Eta model
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A few Marine Case Studies in METAREA VII
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Heavy, very long-period SW’ly swell to Agulhas Bank
- semi-submersibles unprepared, go into resonance. Damage several $m.
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Tropical Cyclone Domoina visits the KwaZulu Natal Coast
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Meteosat 7 – 4 September 2001
HmO 10m + off Cape Townwidespread coastal damage
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Explosive cyclogenesis 24 May 2002. Heavy swell -> coastal damage/ flooding
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Drifting buoy 17513, south-west of Cape Town
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Antarctic Mesoscale Prediction System model - AMPS
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Drifting buoy 71566 – important input for AMPS – wakes up !
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NOAA WAVEWATCH model – buoy data please !
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Concluding Comments :Marine DATA
Life blood – Bread & butter !
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Bouvet AWS data – received 8 hours later ...
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International cooperation versus NMS commercialisation
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Photo : Brent Appel - SAWB
SA Agulhas returning from Marion Is – August 1999