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Ocean wave energy regimes of the circum-polar coastal zone David E. Atkinson International Arctic Research Center / Atmospheric Sciences Department University of Alaska Fairbanks David E. Atkinson International Arctic Research Center / Atmospheric Sciences Department University of Alaska Fairbanks
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David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004 Objective Provide wave energy climatologies for the Arctic Coastal Dynamics Project
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Photos by Julie Baltar, story in the Nome Nugget Shishmaref, AK bluff retreat Shishmaref, AK bluff retreat David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks Impacts – Alaska - communities AGU San Fransisco: December 13, 2004 Photos taken 2 hours apart
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Figure given to me by Tohru Saito, IARC Impacts – Alaska - communities
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Motivation > Wave energy principle forcing agent > Much of the circum-polar coastal zone susceptible to erosion > Problem is not easy - 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 coastal zone susceptible to erosion > Problem is not easy - 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. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004
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Desire: develop a system that will translate winds into wave energy > ERA is available, but - custom development will allow tailoring (e.g. force with winds from HIRHAM, upcoming arctic reanalysis, even AOGCM predicted fields.) > 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 > ERA is available, but - custom development will allow tailoring (e.g. force with winds from HIRHAM, upcoming arctic reanalysis, even AOGCM predicted fields.) > 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 Approach David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004
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Wave energy calculation - 1 st order linear (Airy) approximation > Coastal Engineering Manual and Technical Reference for the Automated Coastal Engineering System (USArmy Corps of Engineers) > suitable for most applications Full complexity of the 3-D fluid structure can not currently be described in its entirety Wave energy calculation - 1 st order linear (Airy) approximation > Coastal Engineering Manual and Technical Reference for the Automated Coastal Engineering System (USArmy Corps of Engineers) > suitable for most applications Full complexity of the 3-D fluid structure can not currently be described in its entirety Scope and Approach David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004
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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 Approach David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004
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Scope and Approach Depth - simply specified at 10m - represents generic shelf zone Sea ice - NSIDC extent plots used - coastal region divided into 12 sectors by longitude - based on ice plots, 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 - coastal region divided into 12 sectors by longitude - based on ice plots, sectors assigned a binary ice/no ice class - turned energy on/off for that month David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004
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ACD zones, weather station locations Results from Arctic Coastal Dynamics project David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004 1 2 3 5 6 7 8 9 10 11 12 4
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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 (180 degree thing) 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 (180 degree thing) Limitations David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004
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David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004 1979 total ICENo ICE
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David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004 1998 total ICENo ICE
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David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004 1979 – 2003 mean ICENo ICE
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David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004 1979 – 2003 trends ICENo ICE
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For example,
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> 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/improvements David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004
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David E. Atkinson IARC/Atm. Sci., University of Alaska Fairbanks AGU San Fransisco: December 13, 2004 > Influence of sea ice apparent even for this coarse approach > Wave energy trends, not just seasonal totals, influenced by sea ice conditions > Influence of sea ice apparent even for this coarse approach > Wave energy trends, not just seasonal totals, influenced by sea ice conditions Conclusions
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