Mr. Patrick CaldwellHawaii LiaisonNOAA/NESDIS Data Center

Photo: Debbie and Kimbal Milikan

Goddard-Caldwell Data Set

Surf Climatology

Analysis and Results

Surf Information: Planningand Protecting Life and Property

- Recreation- Commercial Ventures- Engineering- Transportation- Research- Gov’t Coastal Zone Management- Litigation- Surf forecast validation

User Community

Photo: Patrick Holzman, Location: Kamalino Drive, Kailua, Oahu, November 2003

Motivation

•Goddard-Caldwell surf database the most requested dataset from NOAA Hawaii Data Office

Regional Data Added to the NOAA Posterity Archive

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Number of Unique Requests

Data Category

265 requestssince 10/2001

These are hands-on requests, not automatic transfers from FTP/WWW.

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Services: To Where?

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Services: What Parameters?

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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 51001 since 1981 - buoys 51002-4 since 1984 - Kailua (8/00), Waimea (12/01) Dept. of

OceanographyUniversity of HawaiiKailua Buoy

Surf Observations

Primary Surf Data Sources

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)

Observations in history/science

Hawaiian language:135 words: moods of sea and surf149 words: wind87 words: rain27 words: clouds

Harold Kent, “Treasury of Hawaiian Words in 101 Categories”

Beaufort Wind ScaleDeveloped in 1805 by Sir Francis Beaufort of England

Visual observationsto estimate wind speedsat sea on a scale of 1-12

Other Observations used In science: rogue waves

Waimea buoy

Kailua buoy

Observational Network

Primary reporting locations

North ShoreObservations,1968-present

Goddard-Caldwell Dataset

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

What is the range given in surf reports?(if report given as 10-12 ocn 15, what does that mean?)

29 November, 2004

TemporalVariability

29 November, 2004

Benchmarks(surfers)

Rayleigh Wave Distrubtion

Frequency of Occurrence

Wave height

Most frequentAverage height

Significant height (H1/3)

H1/10H1/100

Surf report: H1/3 to H1/10, ocn H1/100

Simulating Waves Nearshore (SWAN) Model

-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

Incident 2.5 m, 14 second from 315o

315o

Incident 6.5 m, 19 second from 317o

20misobath

Height (m)

Spatial Variability

What makes a dataset valid? Consistency

(1)

where: Hb = shoaling-only predicted wave height at breaking Ho = deep water significant wave height P = dominant wave period g = gravity

H b oH g gP4 5

2 5

1 4//

[( / )( / )]

Methodology: buoy-derived, shoaling-estimated surf height:

Data: - Daily Surf Observations - Buoy 51001 (1981-2002) - Waimea Buoy (2002)

maximum Hb between 7am-5pm

(07-22Z for 51001)

* Conservation of energy flux* Ignores refraction, diffraction, bottom friction, currents, wave-wave interactions, and wind

Following Komar and Gaughan, 1973

Days removed from data: - April - September - strong trades (>22 knots) - dominant period < 12 sec

Temporal Consistency TestSurf Observation minus Buoy-estimated Surf Height

Absolute heights unimportant

Ratio =Difference /EstimatedHeight

Error Estimates

Magnitude of Error increases with height

AverageError ~15%

Wave Climatologies

Most cited reference:MOBERLY,R.J., and CHAMBERLAIN,T., 1964. Hawaiian Beach Systems. Honolulu, Hawaii: University of Hawaii, Hawaii Institute of Geophysics Technical Report No. 64-2, 95p.

ClimatologyFromBuoys

WinterFall

Spring Summer

Ave. Sig. Height (m)

TOPEX 1992-95

Wave Height ClimatologyFrom Altimeters

THE OCEAN ATLAS OF HAWAII(Flament et al, 1996)

Surf Climatology

Caldwell, 2005, JCR

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North Shore Surf Direction Climatology

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Surf Climatology

Caldwell, 2005, JCR

Photo:Jamie Ballenger

Waimea, Jan. 25, 2003, HSF=25

Translation from Hawaii Scale to Trough-to-Crest Heights

Future Talks:

NWSHigh surfadvisory

NWSHigh surfwarning

Empirical Estimate of Surf Height given Offshore Height and Period

Caldwell and Aucan, 2006, JCR

5’

Photo: E.Aeder Surfer: P.Cabrina, Note: Billabong XXL 2004 winner, as 70’

Peahi (Jaws), January 10, 2004, Hsf=27

Caldwell-Aucan Formula,Given 17’ 17sec,H1/3 = 40’H1/10 = 52’H1/100 = 70’

mahalo, aloha, a hui hou

Photo: Patrick Holzman

AcknowledgementsJerome Aucan Waimea buoy data, formula, reviewSteve Businger Review, plotsMark Merrifield, Chris Conger Review

Surf Observations Surf News Network C&C LifeguardsLarry Goddard (1968-1987) 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