Preliminary wave energy hindcast results for the circum-arctic regionPreliminary wave energy hindcast results for the circum-arctic region

David E. AtkinsonInternational Arctic Research Center / Atmospheric Sciences DepartmentUniversity of Alaska Fairbanks

David E. AtkinsonInternational Arctic Research Center / Atmospheric Sciences DepartmentUniversity of Alaska Fairbanks

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To begin with:To begin with:

> Understand the impact of waves

> Understand the importance of storms

- to drive waves

- to drive surges

Examine storm climatology results

> Understand the impact of waves

> Understand the importance of storms

- to drive waves

- to drive surges

Examine storm climatology results

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Atlantic track is prominent at circum-polar scale

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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ACD zones, weather station locations

Results from Arctic Coastal Dynamics projectResults from Arctic Coastal Dynamics project

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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Storm countsStorm counts

David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

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1954

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1996

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2002

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Kar

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Chu

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1975Storm counts by sector

Trends in storm countsTrends in storm counts

David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

- no strong trend

Other influences on coastal erosionOther influences on coastal erosion

In frozen regions must consider

Sea ice

Permafrost

In frozen regions must consider

Sea ice

Permafrost

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Trends in open water season length, 1950 - 2000(model initialized with observations)

Trends in open water season length, 1950 - 2000(model initialized with observations)

David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

Melt season increasingReduced sea ice cover

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-2.0

-1.5

-1.0

-0.5

0.0

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1.0

1.5

2.0

2.5

3.0

-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0

R2 = 0.33 F-stat = 11.8, Pr>F = 0.002

X = (Normallized T + Normallized Energy) Y = (Normallized Erosion)

Results from western Kara Sea coast(S. Ogorodov, Moscow State University)

- influence of wave energy and temperature in permafrost coastal zones

Results from western Kara Sea coast(S. Ogorodov, Moscow State University)

- influence of wave energy and temperature in permafrost coastal zones

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Wave energy climatologies - impetusWave energy climatologies - impetus

> Wave energy principle forcing agent

> Much of the circum-polar (AK) coastal zone susceptible to erosion

> Problem is not easy – various parameters that must be considered

- shallow zones

- sea ice

* ice on/off dates controls wave access

* position of ice offshore controls fetch

(presence of floating ice also modifies wave energy)

> Coastal process models require wave energy input (I.e., and not wind)

> Engineering issues

> Wave energy principle forcing agent

> Much of the circum-polar (AK) coastal zone susceptible to erosion

> Problem is not easy – various parameters that must be considered

- shallow zones

- sea ice

* ice on/off dates controls wave access

* position of ice offshore controls fetch

(presence of floating ice also modifies wave energy)

> Coastal process models require wave energy input (I.e., and not wind)

> Engineering issues

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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Desire: develop a system that will translate winds into wave energy

Driving winds – gridded is desirable

- North American Regional Reanalysis for AK (32 km)

- AOGCM for work with prediction scenarios

> Generate climatological wave fields

- monthly totals

- annual totals

- period means and trends (1979-2003)

Provide to coastal dymanics researchers, but

can also assess contribution of ice

Desire: develop a system that will translate winds into wave energy

Driving winds – gridded is desirable

- North American Regional Reanalysis for AK (32 km)

- AOGCM for work with prediction scenarios

> Generate climatological wave fields

- monthly totals

- annual totals

- period means and trends (1979-2003)

Provide to coastal dymanics researchers, but

can also assess contribution of ice

Scope and ApproachScope and Approach

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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Wave energy calculation

- 1st order linear (Airy) approximation

> Coastal Engineering Manual and Technical

Reference for the Automated Coastal Engineering System

(USArmy Corps of Engineers)

> suitable for most applications

> Represents a starting point only

Wave energy calculation

- 1st order linear (Airy) approximation

> Coastal Engineering Manual and Technical

Reference for the Automated Coastal Engineering System

(USArmy Corps of Engineers)

> suitable for most applications

> Represents a starting point only

Scope and ApproachScope and Approach

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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Wind forcing:

- NCEP/NCAR reanalysis, 925 mb to overcome speed problems

- direction limited to 180° (I.e. water side)

Direct forcing approach, not distribution based

Wind forcing:

- NCEP/NCAR reanalysis, 925 mb to overcome speed problems

- direction limited to 180° (I.e. water side)

Direct forcing approach, not distribution based

Scope and ApproachScope and Approach

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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NCEP/NCAR Reanalysis wind speed problemNCEP/NCAR Reanalysis wind speed problem

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0.7

NCEP/NCAR Reanalysis wind speed problemNCEP/NCAR Reanalysis wind speed problem

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Scope and ApproachScope and Approach

Depth

- simply specified at 10m

- represents generic shelf zone

Sea ice

- NSIDC extent plots used

- based on ice plots:

> coastal region divided into 12 sectors by longitude

> sectors assigned a binary ice/no ice class

- turned energy on/off for that month

Depth

- simply specified at 10m

- represents generic shelf zone

Sea ice

- NSIDC extent plots used

- based on ice plots:

> coastal region divided into 12 sectors by longitude

> sectors assigned a binary ice/no ice class

- turned energy on/off for that month

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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NSIDC Sea Ice extent from passive microwaveNSIDC Sea Ice extent from passive microwave

ACD zones, weather station locations

Results from Arctic Coastal Dynamics projectResults from Arctic Coastal Dynamics project

David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

1

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No depth variation

Winds do not catch all events (spatial resolution)

Ice sector approximation

Ice content (binary approach) coarse

Spatial resoution coarse

Orientation of wind energy wrt coastline crude (hemisphere approach)

No depth variation

Winds do not catch all events (spatial resolution)

Ice sector approximation

Ice content (binary approach) coarse

Spatial resoution coarse

Orientation of wind energy wrt coastline crude (hemisphere approach)

LimitationsLimitations

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

1979 total1979 total

ICE No ICE

David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

1998 total1998 total

ICE No ICE

David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

1979 – 2003 mean1979 – 2003 mean

ICE No ICE

David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

1979 – 2003 trends1979 – 2003 trends

ICE No ICE

> Increase wind forcing resolution

> Introduce local coastal orientation

> Variable depth

> Introduce variable ice concentrations, drop sector approach

> Comparisons with existing observed/modeled information

(e.g. Ogorodov for Pechora Sea)

> Increase wind forcing resolution

> Introduce local coastal orientation

> Variable depth

> Introduce variable ice concentrations, drop sector approach

> Comparisons with existing observed/modeled information

(e.g. Ogorodov for Pechora Sea)

Next steps/improvementsNext steps/improvements

David E. AtkinsonIARC/Atm. Sci., University of Alaska FairbanksA

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David E. AtkinsonIARC/Atm. Sci., University of Alaska Fairbanks

> Trends in (circumpolar) storminess not simple linear

> Ice (marine and terrestiral) must be explicitly considered for erosion work

> Influence of sea ice for wave energy apparent even for this coarse approach

> Wave energy trends, not just seasonal totals, influenced by sea ice conditions

> Trends in (circumpolar) storminess not simple linear

> Ice (marine and terrestiral) must be explicitly considered for erosion work

> Influence of sea ice for wave energy apparent even for this coarse approach

> Wave energy trends, not just seasonal totals, influenced by sea ice conditions

Conclusions from storm and wave energy work:Conclusions from storm and wave energy work:

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FinFin