1. Validity of North Shore, Oahu Surf Observations
Mr. Patrick Caldwell
Hawaii Liaison
NOAA/NESDIS Data Center
Photo: Debbie and Kimbal Milikan

2. Talk Outline Surf Climatology Goddard-Caldwell Data Set
Analysis and Results
Surf Climatology

3. Motivation Surf Information: Planning and Protecting Life and Property
User Community
- Recreation
Commercial Ventures
Engineering
Transportation
Research
Gov’t Coastal Zone
Management
Litigation
- Surf forecast validation
Surf Information: Planning
and Protecting Life and Property
Goddard-Caldwell surf database
the most requested dataset from
NOAA Hawaii Data Office
Photo: Patrick Holzman, Location: Kamalino Drive, Kailua, Oahu, November 2003

4. Regional Data Added to the NOAA Posterity Archive
Number
Of Unique
Acquisitions
(NODC
Accessions)
*since 1998
Updated Dec 28, 2005

5. Who Provided Data? Since 1998 Updated Dec 28, 2005 Number Of Unique
Acquisitions
Since 1998
Updated Dec 28, 2005

6. Regional Data Services
Updated Dec 28, 2005
Regional Data Services
Data Category
Number
of Unique
Requests
265 requests
since 10/2001
These are hands-on requests, not automatic transfers from FTP/WWW.

7. Services: To Where?
Hands-on since 10/2001
Updated Dec 28, 2005

8. Services: What Parameters?
Hands-on since 10/2001
Updated Dec 28, 2005

9. Primary Surf Data Sources:
Buoys and Surf Observations
Buoys
Pros:
- explicit measurements
- gives statistical distribution
(energy spectrum)
- around the clock
Cons:
- not surf, offshore waves
- technical break downs
- limited length
- buoy since 1981
- buoys since 1984
- Kailua (8/00), Waimea (12/01)
Dept. of Oceanography
University of Hawaii
Kailua Buoy

10. Primary Surf Data Sources
Surf Observations
Pros:
- explicit surf heights
- inherent knowledge base
- longest, most continuous
(daily data since 8/1968)
- more locations
Cons:
- subjectivity
- only daylight
- limited statistical distribution
of each report (no spectrum)

11. Observations in history/science
Hawaiian language:
135 words: moods of sea and surf
149 words: wind
87 words: rain
27 words: clouds
Harold Kent, “Treasury of Hawaiian Words in 101 Categories”

12. Beaufort Wind Scale
Developed in 1805 by
Sir Francis Beaufort
of England
Visual observations
to estimate wind speeds
at sea on a scale of 1-12
Other Observations used
In science: rogue waves

13. Observational Network
Goddard-Caldwell
Dataset
Waimea
buoy
North Shore
Observations,
1968-present
Kailua
buoy
Primary reporting locations

14. What is in the Goddard-Caldwell Database?
Daily value
- for given range,
upper end of range
- units: Hawaii Scale
- highest report of day
-North Shore special case
- represents location of
highest reported breakers
Regardless of Height Scale
Course resolution
-difficulties to define temporal
variability
-difficulties to define where along
wave front the height refers to
-which reef is being referred to?
-published literature shows tendency
for underestimation of surf heights

15. Temporal Variability What is the range given in surf reports?
29 November, 2004
What is the range given in surf reports?
(if report given as ocn 15, what does that mean?)

16. Surf report: H1/3 to H1/10, ocn H1/100
Most frequent
Average height
29 November, 2004
Significant height
(H1/3)
Benchmarks
(surfers)
H1/10
H1/100
Wave height
Frequency of Occurrence
Rayleigh
Wave
Distrubtion
Surf report: H1/3 to H1/10, ocn H1/100

17. Spatial Variability Simulating Waves Nearshore (SWAN) Model
Incident 2.5 m, 14 second from 315o
20m
isobath
315o
-Large variations in surf
height along a given
shoreline
-Largest breakers occurs
in zones of high refraction
- this is where surfers go
- this is where reports
are made
Height (m)
Incident 6.5 m, 19 second from 317o

18. What makes a dataset valid? Consistency

21. buoy-derived, shoaling-estimated surf height:
Methodology:
buoy-derived, shoaling-estimated surf height:
Data: - Daily Surf Observations
- Buoy ( )
- Waimea Buoy (2002)
maximum Hb between 7am-5pm
(07-22Z for 51001)
Following Komar and Gaughan, 1973
Days removed from data:
- April - September
- strong trades (>22 knots)
- dominant period < 12 sec
* Conservation of energy flux
* Ignores refraction, diffraction, bottom friction, currents,
wave-wave interactions, and wind

22. Temporal Consistency Test
Surf Observation minus Buoy-estimated Surf Height
Ratio =
Difference /
Estimated
Height
Absolute heights unimportant

26. Error Estimates Magnitude of Error increases with height Average

27. Wave Climatologies Most cited reference:
MOBERLY,R.J., and CHAMBERLAIN,T., Hawaiian Beach
Systems. Honolulu, Hawaii: University of Hawaii, Hawaii
Institute of Geophysics Technical Report No. 64-2, 95p.

30. Climatology
From
Buoys

31. TOPEX
Wave Height
Climatology
From Altimeters
Fall
Winter
THE OCEAN ATLAS OF HAWAII
(Flament et al, 1996)
Spring
Summer
Ave. Sig. Height (m)

32. Surf Climatology
Caldwell, 2005, JCR

33. North Shore Surf Direction Climatology
Days
Per
Month
(> 2 Hsf)
Caldwell, 2005, JCR

34. Surf Climatology
Caldwell, 2005, JCR

35. Translation from Hawaii Scale to Trough-to-Crest Heights
Future Talks:
Translation from Hawaii Scale to Trough-to-Crest Heights
Waimea, Jan. 25, 2003, HSF=25
Photo:Jamie Ballenger

36. Empirical Estimate of Surf Height given Offshore Height and Period
NWS
High surf
warning
NWS
High surf
advisory
Caldwell and Aucan, 2006, JCR

37. Caldwell-Aucan Formula, Given 17’ 17sec, H1/3 = 40’ H1/10 = 52’
Peahi (Jaws), January 10, 2004, Hsf=27
Caldwell-Aucan Formula,
Given 17’ 17sec,
H1/3 = 40’
H1/10 = 52’
H1/100 = 70’ 5’
Photo: E.Aeder Surfer: P.Cabrina, Note: Billabong XXL 2004 winner, as 70’

38. mahalo, aloha, a hui hou Acknowledgements Surf Observations
Surf News Network
C&C Lifeguards
Larry Goddard ( )
Randy Rarick, Peter Cole, Bernie Baker, Albert Benson
Pat’s support:
Garrett McNamara, Clark Abbey, Ian Masterson, Kaleo Ahina, Jerome
Aucan, Nathalie Zilberman, Thomas Decloedt, Cedric Chavanne,
Sean Johnston, Eric Grossman, Yvonne Firing, Kimball Millikan,
Rob Yonover, AJ Harris, Jeff Cotter, Robert Burke, and
websites: Claudia Ferrari’s Daily Surf News, Surfline, and
Jamie Ballinger’s Hawaiian Watershots
Jerome Aucan
Waimea buoy data, formula, review
Steve Businger
Review, plots
Mark Merrifield, Chris Conger
Review
mahalo,
aloha,
a hui hou
Photo: Patrick Holzman