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)=