Investigation of ship accidents usingglobal ERS-2 and ENVISAT wave
modeWolfgang Rosenthal (GKSS)
Susanne Lehner (DLR)Johannes Schulz-Stellenflet (DLR)
Thomas König (DLR)
• 43,600 ships of trade, 1.2 Million people
• Rate of loss 130 Ships p.a.
• 1000 sailors lose their life every year
Quelle: Lloyds Shiffs Register
Case Study-FPSO SchiehallionAccident
The FPSO 'Schiehallion', situated at 60° 21'N, 4° 4'W , sustained heavy weather damage above the waterline on around 22:00 on 9 November1998. The damage was reportedly caused, not by a wave of extremeheight, but by a wave of exceptional steepness.
Wave Model Hindcasts Result
The patch of high Hs passed to the northwest of the Schiehallion site, and part of the ring of steepness has passed over the Schiehallion site from 16:00 to 22:00..
Coincident SAR Image
Parameters along the orbit
Nine Imagettes across the Accident
Cross-spectrum along orbit
Time Series Wave Height at Draupner, Jan, 1st 1995 15:20
Significant Waveheight 11.9m Peak Period 16.7 secMaximum crest Height 18.5 mAdjacent trough -7.1m and –6.5mDepth 70m
Return Period of 1-5 years
Higher than the 100 year cres
Draupner oil platform
position:58, 11 N / 2,28 E
70 m water depth
Draupneroil platform
e1_18115_2421_slc01-01-1995, 10:49 h UTC100 x 100 km
5 x 10 km
Wave Elevation Draupner
Spectrum North above
Spec Draupner upper right
Spectrum South lower right
23m/sec
01.01.1995 (storm track) 01.01.1995 Hs (--) & mslp
A. Sunde, Norwegian Met office
Draupner58, 11 N / 2,28 E
FINO
Storm case over the North Sea ( 01.11.2006, 10:26 UTC )
MERIS FR LEVEL 2aquired on Nov 01, 2006
ASAR WSMaquired on Nov 01, 2006
Conclusions• Wave forces on the ship hull depend largely on
maximum steepness of the encounteredindividual waves already at moderate waveheight.
• Individual wave height is important to reach thesensitive parts of the ship (deck areas, windows, doors, etc.)
• To determine the shape and the height of individual waves radar satellites are crucial. Themodern wave models are of no help. They onlydeliver average sea state parameters ( no geophysical variability).
Maximum Wave HeightDistribution from Satellite
3 weeks of Southern winter in 1996
Spectra from 3-D Analysis
1-D Spectrum
0
0,5
1
1,5
2
2,5
3
3,5
0 0,05 0,1 0,15 0,2Frequency [Hz]
Energy density E(f)
0,01 0,05 0,09 0,13 0,16 0,20-180
-135
-90
-45
0
45
90
135
180
Frequency [Hz] .
2-D Spectrum
0-0,2 0,2-0,4 0,4-0,6 0,6-0,8 0,8-1
* First gauge
* Second gauge
Schlußfolgerungen• Neigung der Ozeanoberfläche ist aus dem Radarsignal
bestimmbar.
• Die Ozeanoberfläche ist aus der Neigung bestimmbar.
• Der Fehler für den mittleren Seegang aus Radarmessungen hat
die Größenordnung wie Messungen von in-situ Sensoren (10%
der Wellenhöhe).
• Einzelwellen sind meßbar
Conclusions• Individual Waves are Extractable
• Validation at Ekofisk
• Global Maps for extreme Wave Height
• MTFTilt is Empirically Determinable
• Validation against a waverider buoy and a
Laser Array
• Sea Surface is Retrieved from Marine Radar
and SAR Satellite Images
Conclusions
• Sea Surface is Retrieved from Radar-
Image Sequences
• HS,Radar has same Standard Deviation
like In-Situ Sensors
• Individual Waves are Extractable
Vortragstitel 40
2-Year Maximum Significant Wave Height (CWAVE-1.0)=