casey thornbrugh science research mentors: amanda h. lynch & elizabeth n. cassano cooperative...

Casey Thornbrugh

Science Research Mentors: Amanda H. Lynch & Elizabeth N. CassanoCooperative Institute for Research in the Environmental Sciences

University of Colorado, Boulder

Science Writing Mentor: Nancy DawsonSignificant Opportunities in Atmospheric Research and Science

University Corporation for Atmospheric Research

Simulating Wave Heights and DirectionsAlong the Coast

OfBarrow, Alaska

Contributing to the PredictionOf

Coastal Flooding:

Background

The Alaska North Slope Region

Research Problems

Methodology

Data Used

Description of SWAN wave simulations

Results

Conclusions

William ManleyINSTAAR

100 meter pixel size

Digital Elevation Model of the Alaska North Slope

Beaufort Sea

Chukchi Sea

The Alaska North Slope Region

Coastal flooding models incorporating tidal fluctuations

and storm surges, have often produced results where

the simulation of coastal flooding was below the actual

observed coastal flooding.

There is a lack of raw data consisting of wave height

measurements and wave directional data offshore or

in the Barrow coastal region.

The Research Problems

The Naval Arctic Research Lab (NARL)(Approximately 1.5 miles north of Barrow)

October 1963

Photo courtesy of Grace Redding, 1963

October 1963 Flood Extent with 12 and 16 Foot Contours for Barrow, Alaska

Flood map constructed by Leanne Lestak, William F. Manley, and James Maslanik, August 2003. The October 1963 flood extent was mapped by Hume and Schaulk, 1967.

ChukchiSea

The purpose of this project is the use of the

Simulation of Waves Near shore (SWAN) model to

simulate wave heights and directions offshore and

in

the Barrow coastal region.

Incorporating the results from from the SWAN

model

with a storm surge model for Barrow, will allow a

total

flood height to be simulated and compared with

past, observed coastal flooding.

Purpose

Bathymetry map of the Barrow coastal region

Image provided by Leanne LestakCooperative Institute for Research in Environmental Science


Barrow

ChukchiSea

BeaufortSea

Bathymetry of the Barrow Coastal Region

Bathymetry of the Barrow coastal region compiled with data from NOAA and NGDC

Daily and average monthly sea ice concentration data from NSIDC

Daily average wind speeds and directions for 11 historical storms from the Barrow NWS office

Hourly wind speeds and directions for the 29 July 2003 storm from the Barrow NWS office

The computational grid will represent an area 390 by 390 km over the Alaska North Slope coastline and the Chukchi/Beaufort Seas.

Data

Bathymetry Input Grid for SWAN

Image provided by Leanne LestakCooperative Institute for Research in Environmental Science


The Simulation of Waves Near shore Model

SWAN is a wave simulation model specificallydesigned to simulate wave heights for shallow coastal areas.

Input data for SWAN includes:

Wind direction and speed

Location and shape of the shoreline

Bathymetry of the coastal seafloor

SWAN


SWAN is a wave simulation model specificallydesigned to simulate wave heights for shallow coastal areas.

Additional input data for SWAN included:

Sea ice edge

Prescribed boundary conditions (wave height & direction)

SWAN


SWAN

SWAN wave simulations were run for:

I. 11 historical late summer & fall storms occurring from 1 August 1950 through 31 August 2000

A. Input of a constant wind speed and direction for each storm

B. Added sea ice edge

C. No prescribed boundary conditions

SWAN wave simulation model simulated wave

heights and directions offshore and in the Barrow

coastal region

High winds from any direction produced high

waves offshore.

High westerly winds produced the highest waves in

the Barrow coastal region.

Results (part one)

Sea ice-edge covering greater than 50% of the sea

surface moderately reduced the wave heights

offshore and in the Barrow coastal region.

Results (part one)

24 October 1998

Wave heights (cm) wave direction (degrees x 10 ^ -1)

Wind speed: 17.0 m/s

Wind direction: 70° (East/Northeast)

High easterly winds

Wind directionWave direction

Alaska North Slope Alaska North Slope




Wind direction: 225° (Southwest)

20 September 1986Moderate southwesterly winds





Wind direction: 270° (West)

3 October 1963High westerly winds



Sea ice edge Sea ice edge



Wind direction: 68° (East/Northeast)

24 August 1950Moderate easterly winds with extended sea ice-edge



Sea ice edge Sea ice edge


SWAN

SWAN wave simulations were run for:

II. 6-hourly time steps for the 29 July 2003 storm

A. Input of the average wind speed and direction for every 6 hrs

B. Wind data 7 PM 28 July through 7 AM 30 July (Alaska time)

C. Prescribed boundary conditions

D. No sea ice edge

Results (part two)

SWAN wave simulation for 29 July 2003 produced

maximum offshore wave heights of 5 to 5.6 m

consistent with the NWS Barrow office marine

forecast of waves 5 to 6 m for this storm.

Simulation produced maximum wave heights of 4.6

m, consistent with the 4 to 5 m waves observed

near shore by the NWS.

Boundary conditions permitted a realistic lag time for

changes in wave direction in response to changes in

the wind direction.

Results (part two)

29 July 2003 1 AM



Wind direction: 211° (South/Southwest)

Boundary conditions: wave height = 0.8 m

wave direction = 225° (Southwest)


Alaska North SlopeAlaska North Slope



Wind direction: 251° (West/Southwest)


wave direction = 215° (Southwest)

29 July 2003 7 AM





Wind direction: 270° (West)


wave direction = 245° (West/Southwest)

29 July 2003 1 PM




Wind speed: 9.1 m/s

Wind direction: 289° (West/Northwest)


wave direction = 270° (West)

30 July 2003 7 AM



Knowing the contribution of waves to coastal flooding will improve the ability to predict the total flood heights.

This information exposes areas of Barrow that are vulnerable to flooding and allows community members to develop ways to protect these areas.

Conclusions

Science Research Mentors:

Amanda H. Lynch & Elizabeth N. Cassano

Cooperative Institute for Research in the Environmental Sciences


Science Writing Mentor:

Nancy Dawson

Significant Opportunities in Atmospheric Research

and Science

SOARS Staff & Protégés

Acknowledgements

Leanne Lestak

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