First year sea ice: here today, here tomorrow

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First year sea ice here today, here
tomorrow What can be learned from sea ice in the
Barrow region? Bonnie Light Polar Science
Center APL/UW Science and Education
Opportunities for an Arctic Cabled Seafloor
Observatory February 7- 8, 2005
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2004/106 - 04/15 at 22 10 UTCSatellite Terra -
Pixel size 1km 1150 km x 850 km
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Radarsat-1 Standard Beam 4 SAR image June 19
2004 pixel size100 meters 1024 x 1024 pixels
(102.4 x 102.4 km).
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June 2002
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Land-fast ice

• Seasonal
• Significant impact on terrestrial processes,
  such as coastal permafrost heat budget,
  vegetation patterns, and indigenous subsistence
  activities
• Rich history of surface ice observations
• Ice is stationary most of the time, but is
  shaped by dynamic events that can occur very
  quickly
• e.g., ice push, breaking from coast
• understanding very important to local community
• useful for studying thermodynamics
• Arctic Coastal Ice Processes www.arcticice.org
• Barrow ice cam http//www.gi.alaska.edu/eicken/h
  e_proj/BRWICE/bcam1.htm
• Barrow Coastal Sea Ice Radar

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Mass balance studies on land-fast ice
Perovich, D.K., T.C. Grenfell, H. Eicken, J.A.
Richter-Menge, M. Sturm, K. Ligett, K. Frey, 
G.A. Maykut, B. Elder, A. Mahoney, J. Holmgren,
K. Claffey, T. George, Arctic Coastal Processes
Data Report 2001 CD-ROM, October, 2001.
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Pack Ice

• 100 km off shore
• Dynamic environment opening, ridging, rafting
• Dynamics complicate study of thermodynamics
• No IABP buoys this close to shore
• Aerosonde observations (Curry et al.)

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Flaw zone

• Flaw zone occupies space between land-fast ice
  and coherent pack ice
• Very dynamic
• Westward-drifting ice encounters fewer landmasses
  (and hence less resistence) once it passes Pt
  Barrow (semipermanent polynya)
• Adequate predictions of ice integrity and an
  understanding of behavior of ice in flaw zone is
  of critical importance to community
• Areal extent of zone increasing in regions where
  retreat of perennial ice is pronounced
• Flaw zone has received less detailed or long-term
  study than land-fast or pack ice

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Landfast ice/leads project (Eicken and
colleagues) http//mms.gina.alaska.edu/Ice_classif
ication.html
Determination of SLIE (Seaward Landfast Ice
Edge) The SLIE determined from mosaics between 3
and 27 April 2003
The SLIE determined from mosaics between 23
February and 19 March 2003
The SLIE determined from mosaics between March 16
and 18 2000. In the center of the mosaic the SLIE
coincides with a lead separating moving sea ice
from ice that had remained stationary since
February 23. To the east, the SLIE coincides with
a line along which differential movement of ice
was observed with little/no open water.
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SLIEs delineated for 2001, 2002, and 2003. The
color of the line represents the number of SLIEs
occurring within 1 km of each other. Hi
co-occurrence values indicate regions where the
SLIE is more stable. It seems that there are
stable nodes along the SLIE, separated by regions
of more variability, suggesting that grounded
ridges do not occupy the entire SLIE.
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Whats the problem?

• Trends in ice concentration show increases in
  winter, decreases in summer (1979-2000).

http//nsidc.org/data/seaice_index/
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The Dramatic Thinning of Arctic Sea Ice,
1988-2003 R. W. Lindsay and J. Zhang Polar
Science Center, University of Washington,
Seattle, WA Submitted to Journal of Climate, 15
November 2004
Figure 4. Trend in the ice thickness for the
16-yr period 19882003 for all ice, level ice,
and ridged ice.
Figure 8. Spatial patterns of the trends in the
annual thermodynamic growth and net advection for
the 16-yr period 19882003. The sum of these two
fields gives the trend in the mean ice thickness
seen in Figure 4a.
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If we want to understand these changes...

• Need to understand relative roles of dynamics and
  thermodynamics
• First-year ice is here to stay and may even be
  the dominant ice type of the future

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How can we progress?

• Study Flaw Zone
• A better understanding of flaw zones will yield
  insight into Arctic-wide change
• Snow accumulation on ice in conjunction with
  thinner ice may be causing regional flooding,
  inducing top-surface snow-ice formation
• SIZs could begin to resemble Antarctic
  conditions- implications for biodiversity
• Study at fixed location in Western sector (e.g.
  Barrow)
• Significant advantage to establishing a node in
  this dynamic environment

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Approaches

• Acoustic sensors
• ULS (1D)
• Scanning ULS (2D)?
• ADCP
• Radiative sensors
• Passive Upward looking radiometers
• Active LIDAR
• Frazil formation within water column
• Optical sediment traps
• Visual sensors
• Upward looking camera with active lighting
• Important to look where there is plenty ice
  motion
• Need climatology
• 1-D and 2-D observations

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Mean annual wind direction frequency distribution
()for non-calm observations.
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Figure from mahoney et al.
Figure 4 The seaward landfast ice edges (SLIE's)
delineated from 31 gradient difference images for
the whole study region from east of Point Lay to
the Mackenzie Delta. See text for explanation.
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Barrow lat/long 71 17'N / 156 46' W