X-Band radar as a tool to determine spectral and single wave properties

Transcription

1 X-Band radar as a tool to determine spectral and single wave properties Konstanze Reichert November 2004

2 History of WaMoS II 25 Years of progress Application of WaMoS II for offshore and shipping WaMoS wave data MaxWave & SinSee- Single wave detection Recent developments and future applications

3 15 Years of WaMoS development at the German research centre GKSS 1991, 1992, 1995 Testing of the equipment on German RV Gauss, 1994/1996 Technology transfer to commercialise WaMoS II 1997: Prototype of today's WaMoS Technology deep water applications 1998: Operational Measurements in shallow waters and on board ships 1998: Since then continuos participation in international research projects 2001: Type approval by Germanischer Lloyd and Det Norske Veritas 2003: MaxWave- Beginning of single wave detection - continued 2004: Implementation of high resolution bathymetry and current measurements

4 WaMoS II components

5 1 Radar polar image A measurement consists of a consecutive series of images. The antenna is located at the centre of the image

6 WaMoS radar images from the Dutch coast, time series of 'seaclutter' image' with directional unambiguity Corresponding 2-dimensional spectrum

7 Example of User Interface WaMoS II - Wave Monitoring System Directional Wave Spectrum Average Surface Current Vector dar age 1-D D Frequency Spectrum Time Series of Hs and Tp

8 Explorer of the Seas: Surface currents Explorer of the Seas, Jan. 24, 2003 MIAMI 25 N 85 W 80 W COZUMEL 20 N

9 Wave Variability in Florida Current WaMoS N II - Wave Monitoring System N Ship Course Current Ship Course Current Ship Course N Current 13kn 1.0m/s 11kn 0.7m/s 17kn 1.5m/s T = 10 s T = 15 s T = 5 s E W T = 10 s T = 15 s T = 5 s E W T = 10 s T = 15 s T = 5 s E S S S normalized wave energy density normalized wave energy density normalized wave energy density Date Hs T p? p L p Jan 24, 2003, 06:00 UTC 2.2m 7.8s m Jan 24, 2003, 10:00 UTC 2.3m 8.7s m Jan 24, 2003, 19:57 UTC 3.8m m

10 amos II on Ekofisk 2/4 atform, since 1992 onocophillips WaMoS II on FINO offsho wind test platform, since 2 Federal Maritime and Hydrographic Agency Helgoland

11 Ekofisk 2/4 platform, in operational use since 1992 by ConocoPhillips Ref Time [day of Jan./Feb., 2000] Significant wave height HS, WaMoS II (red) and reference sensor (blue), in the period of Jan. 28 till Feb. 6, 2000, Values are 20 minute averages. Data: ConocoPhillips

12 Data comparison: WaMoS II with a buoy: Helgoland 1999 October November Dec. WaMoS II on Helgoland since 1998, operated by OWS - shallow water application

13 EU-project MaxWave, Forecast and global statistics of extreme waves Ship accidents caused by freak waves height (m) GKSS DLR TUB OWS KUL MetNo UKMetoffice MeteoFrance IST DNV time (sec) time

14 National project SinSee ( ) Flensburg ship yard Technical Uni -Berlin Technical Uni-Hamburg/Harburg Hamburg ship model basin OceanWaveS

15 MaxWave EU-Project- SinSee Bmbf Inversion scheme G(x,y,t) t = t t = t t = 2 t 3D - FFT t = 2 t t = 3 t I ( k, ω ) t = 3 t Dispersion relation w (k)... t = N t E ( k, ω ) t = N t 3D FFT -1 ζ (x,y,t)

16 Ekofisk, April 16, 2001, 17:00 UTC Radar backscatter N WaMoS: Hs= 4.3 m Tp = 9.8 s mask area Radar Return Maximum qp = 355 lp = 143 m Minimum

17 Ekofisk, April 16, 2001, 17:00 UTC Sea surface elevation N 4,5 m Individual waves Crest length Wave transformatio Wave groups mask area Surface Elevation - 4,5m

18 Ekofisk, April 16, 2001, 17:00 UTC Frequency direction spectrum N Ship W T = 10 s T = 15 s T = 5 s 0.4m/s E WaMoS: Hs= 4.3 m Tp = 9.8 s qp = 355 lp = 143 m S normalized wave energy density

19 Ekofisk, April 16, 2001, 17:00 UTC directional wave finding 4,5 m N Hs = 4.3 m θ p = 355 Mask area 0 1 x [km] Surface Elevation -4,5 m H max = 8.8 m N waves = 739 lmax = 1.5*lp H 1/3 = 4.5 m

20 Transect of sea surface elevation map Ekofisk, April,16, :00 UTC Temporal transect: - individual wave period Ti = 10.2 s (spectral wave period Tp = 9.8 s) Spatial transect: - individual wave length λt = m (spectral wave length λp = m)

21 Wave number spectrum at Ekofisk May, , 15:05 UTC Hs = 4.5 m Tp = 9.2 s λp = 133 m

22 Sea surface elevation map Ekofi May, , 15:05 UTC Data: Phillips petrol, MetNo Hs = 4.5 m Tp = 9.2 s lp = 133 m Hmax = m

23 WaMoS II - Wave Monitoring System Validation of sea surface elevation FINO, January 13, 2004, 03:12 UTC Comparison of sea surface elevation between WaMoS II and buoy Buoy: original and adjusted temporal resolution η [m] Buoy t = 0.78 s Buoy t = 2.50 s 20 t [s] WaMoS II and Buoy 2 η [m] WaMoS II Buoy 20 t [s] 40 60

24 Hmax/Hs > 2? Extreme wave criterion for 2D data is needed Ekofisk, May 29, 2001, 00:00 UTC ntil May 29, 2001, 20:00 UTC FINO, January 13, 2004, 12:00 UTC until January 14, 2004, 15:00 UTC m m 2 29 May, 15: May, 16:15 1 0:00 5:00 10:00 15:00 20:00 Time [Hours of May 29, 2001] Hs, Hmax [m] Hmax/Hs m 4.2 m 13 Jan., 23:02 13 Jan., 14: :00 18:00 24:00 6:00 12:00 Time [Hours of January 13/14, 2004]

25 High resolution current and water depth measurements Example from the Danish Coast from March 31, An extensive validation with independent measurements, for both currents and water depth is currently carried out. Implementation in standa software expected by spring 2005.

26 nclusions and future applications amos II delivers the 2D-wave spectrum and average current in real time amos II has made further advancements for single wave detection igh resolution currents and bathymetry can be derived he research that has been carried out within MaxWave and SinSee should be continued alidation of individual wave data efinition of critical parameters: wave groups, extremes xtreme statistics for 2-D data ransfer to ship application ediction when does the wave reach the vessel what are the changes of its properties