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A Satellite-Derived Climatology of A Satellite-Derived Climatology of Global Ocean WindsGlobal Ocean Winds

Thesis Committee:

Prof. Dudley Chelton

Prof. James Good

Prof. Michael Freilich

Prof. Stanley Gregory

Craig Risien

MS Thesis Defense

26 January 2006

http://cioss.coas.oregonstate.edu/cogow

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Presentation OutlinePresentation Outline

• Introduction

• Previously Published Atlases – Marine Climatic Atlas of the World

– Atlas of Surface Marine Data 1994

• A Scatterometer-based Climatology of Global Ocean Winds (COGOW)– An introduction to Dual Pencil-Beam Scatterometry

– Ehime Maru: A case study

– Examples of Observable Phenomena Within COGOW

• Conclusions

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IntroductionIntroduction

• Winds influence the ocean at all scales– Surface gravity waves & large-scale ocean currents

• Winds affect exchanges between the ocean & the atmosphere– Heat, moisture, gases & particulates

• Winds are important from a societal standpoint– Oil and gas companies & oil spill responders

– Coast Guard search and rescue operations

– Resource managers

– Commercial/recreational maritime activities

– High school and university natural science instructors

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Previously Published AtlasesPreviously Published Atlases

• Marine Climatic Atlas of the World (1850-1970)

• Atlas of Surface Marine Data 1994 (1945-1989)

• Derived primarily from in situ ship and buoy observations, that are highly variable in time and space

• Large portions of the tropics and the southern oceans are significantly under-sampled

• They cannot truly resolve global ocean winds

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Previously Published Atlases (Cont.) Previously Published Atlases (Cont.)

• Marine Climatic Atlas of the World (1850-1970)– http://www.nesdis.noaa.gov/

– Valley Library (Compact Disc)

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• Atlas of Surface Marine Data 1994 (1945-1989) – http://ingrid.ldgo.columbia.edu/

Previously Published Atlases (Cont.)Previously Published Atlases (Cont.)

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The Climatology of Global Ocean WindsThe Climatology of Global Ocean Winds(COGOW)(COGOW)

• 5-Year Climatology (August ’99 - July ’04)– monthly composite maps (wind speed & direction)

– wind rose plots (frequency of wind speed & direction)

• Data derived from NASA’s Quick Scatterometer (QuikSCAT)

• High spatial resolution (0.5ox0.5o)

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An Introduction to Dual Pencil-Beam An Introduction to Dual Pencil-Beam ScatterometryScatterometry

• SeaWinds scatterometer launched on 19 June 1999 onboard the QuikSCAT satellite (August 1999 - Present)

• SeaWinds is an active microwave radar

• Measures 10-m vector winds (25 km2) using electromagnetic backscatter from a wind roughened ocean surface

• Accuracy: 1.68 m.s-1 and 14o

(equivalent to the accuracy of well calibrated buoys)

• ~ 90 % daily global coverage

http://winds.jpl.nasa.gov/

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An Introduction to Dual Pencil-Beam An Introduction to Dual Pencil-Beam Scatterometry (Cont.)Scatterometry (Cont.)

• Why microwave remote sensing?

Figure courtesy of M. Freilich

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An Introduction to Dual Pencil-Beam An Introduction to Dual Pencil-Beam Scatterometry (Cont.)Scatterometry (Cont.)

• So how is it that QuikSCAT measures wind speed and wind direction over the ocean?

http://meted.ucar.edu/

Gravity capillary waves ( 2 cm)

Figure courtesy of M. Freilich

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An Introduction to Dual Pencil-Beam An Introduction to Dual Pencil-Beam Scatterometry (Cont.)Scatterometry (Cont.)

The Model Function relates surface wind speed and relative

wind direction, radar viewing geometry, and backscatter

cross section

Figures courtesy of M. Freilich

( , ; , , )o rf U p

Wind Speed (Independent of Direction)

Viewing GeometryRelative Wind

Direction

Radar Signal Wavelength

Radar PolarizationBackscatter cross

section

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Ehime MaruEhime Maru: A Case Study: A Case Study

• 9 February 2001 USS Greeneville (Los Angeles class submarine) collided with a Japanese training and fishing vessel Ehime Maru

• Ehime Maru sank in ~ 600 m of water, ~17 km south of Diamond Head (Oahu, Hawaii)

• 26 of 35 crew members were rescued

• 9 remaining crew members were assumed trapped inside the vessel

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The Recovery OperationThe Recovery Operation

• Under mounting int’l pressure the US Navy agreed to attempt to recover Ehime Maru crewmembers, their personal effects, and certain unique characteristic ship components

• National Environmental Policy Act (NEPA), 1969 – Environmental Assessment (EA)

• EA resulted in a Finding Of No Significant Impact (FONSI)

• Reef Runway, preferred shallow-water recovery site

Department of the Navy (2001)

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The Recovery Operation (Cont.)The Recovery Operation (Cont.)

• Based on the Reef Runway shallow-water recovery site, NOAA OR&R modeled the behavior of an uncontained diesel fuel release over a 24 hour period– wind direction

– tide conditions (ebb or flood)

• Model constants – wind speed (10 knots), 10 year August mean at Honolulu Int’l

– diesel fuel released (20,000 gallons)

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NOAA OR&R Model ResultsNOAA OR&R Model Results

Ebb Tide Flood Tide

Department of the Navy (2001)

East Wind

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NOAA OR&R Model Results NOAA OR&R Model Results (Cont.)(Cont.)

Ebb Tide Flood Tide

Department of the Navy (2001)

East-Northeast Wind

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Two Questions AriseTwo Questions Arise

1. How representative is the assumed wind speed of 10 knots?

2. How variable is the August wind field off the island of Oahu in terms of wind direction?

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NDBC Buoy LocationsNDBC Buoy Locations

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NCEP NCEP vsvs. COGOW . COGOW

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Climatology of Global Ocean WindsClimatology of Global Ocean Winds

http://cioss.coas.oregonstate.edu/cogow

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COGOW ScreenshotCOGOW Screenshot

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Ehime MaruEhime Maru: A Summary: A Summary

1. How representative is OR&R’s wind speed of 10 knots?2. How variable is the August wind field off the island of Oahu in

terms of wind direction?

• COGOW shows average wind speed of 15-20 knots

• COGOW shows low variability in wind direction (98% E-ENE)

• OR&R results showed high potential for beach contamination during east & east-northeast wind events for both ebb & flood tide conditions

• If the fuel tanks of Ehime Maru had ruptured during the recovery operation, the responders may have been somewhat unprepared for the resulting oil spill

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Examples of Observable Phenomena Examples of Observable Phenomena Within COGOWWithin COGOW

• The South Asian Monsoon

• Evidence of SST & wind field coupling

• Gap Winds

• Corner Accelerations

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The South Asian MonsoonThe South Asian Monsoon

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Evidence of SST & Wind Field CouplingEvidence of SST & Wind Field Coupling

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Gap WindsGap Winds

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Corner AccelerationsCorner Accelerations

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ConclusionsConclusions• COGOW is a 5-year (August 1999 - July 2004) climatology of the

QuikSCAT dataset

• It provides the first high spatial resolution, observationally based, atlas of global ocean winds

• This global coverage provides valuable information about the wind statistics in the many regions of the world ocean that are sparsely sampled by ships and buoys

• COGOW enables users to retrieve wind statistics, both in tabular and graphic form, for any region of interest through an easy-to-use web interface

• The west coast regional node of NOAA’s CoastWatch project has expressed interest in including COGOW in their suite of satellite ocean remote sensing data products

• It is hoped that this new product will be made available in 2006

http://cioss.coas.oregonstate.edu/cogow

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AcknowledgementsI would like to thank, first and foremost, my advisor, Prof. Dudley Chelton, for his guidance and support,

throughout my graduate career here at OSU. Thank-you for believing in me. I would also like to thank

the members of my committee, Prof. James Good, Prof. Michael Freilich and Prof. Stanley Gregory, as

well as NOAA OR&R for their input and interest in this project.

Thanks to my friends in Burt 426, Antonio, Eric, Larry, and Renellys for various discussions and help

with regards to Matlab, JavaScript, Cal-Comp, HTML and data analysis. But more importantly, thanks

for all the laughs, beers, fishing trips, bowling nights, ski days, hikes, barbecues, and coffee and lunch

breaks.

To all the people within COAS and OSU who have touched my life both personally and

professionally over the past 2.5 years, thank-you.

I want to express my sincere appreciation for the unwavering support that I have received from my

partner, Julie Barr, and from my friends and family in South Africa, the UK and Holland.

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Questions?Questions?