Positive trend in the mean speed and deformation rate of Arctic sea ice, 1979–2007

Using buoy data from the International Arctic Buoy Program, we found that the sea ice mean speed has substantially increased over the last 29 years (+17% per decade for winter and +8.5% for summer). A strong seasonal dependence of the mean speed is also revealed, with a maximum in October and a minimum in April. The sea ice mean strain rate also increased significantly over the period (+51% per decade for winter and +52% for summer). We check that these increases in both sea ice mean speed and deformation rate are unlikely to be consequences of a stronger atmospheric forcing. Instead, they suggest that sea ice kinematics play a fundamental role in the albedo feedback loop and sea ice decline: increasing deformation means stronger fracturing, hence more lead opening, and therefore a decreasing albedo. This accelerates sea ice thinning in summer and delays refreezing in early winter, therefore decreasing the mechanical strength of the cover and allowing even more fracturing, larger drifting speed and deformation, and possibly a faster export of sea ice through the Fram Strait. The September minimum sea ice extent of 2007 might be a good illustration of this interplay between sea ice deformation and sea ice shrinking, as we found that for both winter 2007 and summer 2007 exceptionally large deformation rates affected the Arctic sea ice cover.

[1]  Cecilia M. Bitz,et al.  Dynamics of Recent Climate Change in the Arctic , 2002, Science.

[2]  Julienne C. Stroeve,et al.  Arctic Sea Ice Extent Plummets in 2007 , 2008 .

[3]  H. Stern,et al.  Sea ice rheology from in-situ, satellite and laboratory observations: Fracture and friction , 2007 .

[4]  Bruce C. Elder,et al.  Exploring Arctic Transpolar Drift During Dramatic Sea Ice Retreat , 2008 .

[5]  David Marsan,et al.  Scale dependence and localization of the deformation of Arctic sea ice. , 2004, Physical review letters.

[6]  Josefino C. Comiso,et al.  Accelerated decline in the Arctic sea ice cover , 2008 .

[7]  D. Sulsky,et al.  Arctic Ice Dynamics Joint Experiment (AIDJEX) assumptions revisited and found inadequate , 2007 .

[8]  Ulrike Wacker,et al.  Influence of leads in sea ice on the temperature of the atmospheric boundary layer during polar night , 2008 .

[9]  Michael Steele,et al.  Arctic Sea Ice Retreat in 2007 Follows Thinning Trend , 2008 .

[10]  Judith A. Curry,et al.  Determination of surface turbulent fluxes over leads in Arctic , 1997 .

[11]  Ron Kwok,et al.  Fram Strait sea ice outflow , 2004 .

[12]  L. Hinzman,et al.  Observations: Changes in Snow, Ice and Frozen Ground , 2007 .

[13]  J. Wallace,et al.  Response of Sea Ice to the Arctic Oscillation , 2002 .

[14]  Ron Kwok,et al.  Contrasts in sea ice deformation and production in the Arctic seasonal and perennial ice zones , 2006 .

[15]  Ron Kwok,et al.  Variability of Fram Strait ice flux and North Atlantic Oscillation , 1999 .

[16]  R. Colony,et al.  Sea ice motion in response to geostrophic winds , 1982 .

[17]  Donald M. Thomas,et al.  The quality of sea ice velocity estimates , 1999 .

[18]  J. Wallace,et al.  The Arctic oscillation signature in the wintertime geopotential height and temperature fields , 1998 .

[19]  Gary A. Maykut,et al.  Large‐scale heat exchange and ice production in the central Arctic , 1982 .

[20]  A. Thorndike.  Kinematics of Sea Ice , 1986 .

[21]  E. Schulson,et al.  Compressive shear faults within arctic sea ice: Fracture on scales large and small , 2004 .

[22]  M. Holland,et al.  Arctic sea ice decline: Faster than forecast , 2007 .

[23]  Marika M. Holland,et al.  Perspectives on the Arctic's Shrinking Sea-Ice Cover , 2007, Science.

[24]  L. Richardson,et al.  NOTE ON EDDY DIFFUSION IN THE SEA , 1948 .

[25]  D. Rothrock,et al.  Recent Changes in Arctic Sea Ice: The Interplay between Ice Dynamics and Thermodynamics , 2000 .

[26]  W. Collins,et al.  Simulation of aerosol distributions and radiative forcing for INDOEX: Regional climate impacts , 2002 .

[27]  Donald B. Percival,et al.  The decline in arctic sea‐ice thickness: Separating the spatial, annual, and interannual variability in a quarter century of submarine data , 2008 .

[28]  Donald K. Perovich,et al.  Sunlight, water, and ice: Extreme Arctic sea ice melt during the summer of 2007 , 2008 .

[29]  R. Colony,et al.  An estimate of the mean field of Arctic sea ice motion , 1984 .

[30]  Michael Karcher,et al.  State of the Arctic Report. , 2006 .

[31]  J. R. Philip.  Diffusion by Continuous Movements , 1968 .

[32]  Seelye Martin,et al.  Dispersion of sea ice in the Bering Sea , 1985 .

[33]  Pierre Rampal,et al.  Scaling properties of sea ice deformation from buoy dispersion analysis , 2008 .

[34]  Ron Lindsay,et al.  The thinning of Arctic sea ice, 1988-2003 : Have we passed a tipping point? , 2005 .

[35]  Harry L. Stern,et al.  Sea ice kinematics and surface properties from RADARSAT synthetic aperture radar during the SHEBA drift , 2002 .