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October 27, 2003
Seattle, Washington, USA

Sub-diurnal Mesoscale Sea Ice Deformation in the Spring Beaufort Sea Seasonal Ice Zone and its Influence on the Sea Ice Mass Balance

Jennifer K. Hutchings¹, Joe Lovick², William D. Hibler^3
1International Arctic Research Center (IARC), University of Alaska-Fairbanks, PO Box 757320, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7569, Fax 907-474-2643, jenny@iarc.uaf.edu
²IARC, University of Alaska-Fairbanks, 930 Koyukuk Dr., Fairbanks, AK, 7320, USA, Phone 907-474-7569, Fax 907-474-2643, joh3@anatexis.com
³International Arctic Research Center, University of Alaska-Fairbanks, PO Box 757320, Fairbanks, AK, 99775-7320, USA, Phone 907-474-7569, Fax 907-474-2643, billh@iarc.uaf.edu

We report the findings from a mesoscale ice deformation experiment performed at the ONR ICEX ice camp in the Beaufort Sea, 73N 146W, March 26th to April 27th 2003. The camp was at the edge of the multi-year pack north of Prudhoe Bay. On March 26th a lead opened close to the camp, and this lead was monitored continuously for 3 weeks. GPS receivers were placed in an array around the lead, and position recorded every ten seconds. The deformation and strain rate are calculated and compared to personal airborne observations of larger scale deformation features in the coastal shear zone.

The sub-diurnal features of the lead scale deformation are investigated and analyzed in relation to synoptic scale forcing of the ice pack. The lead is found to have a 12 hour and 24 hour cycle in divergence and shear. The character of the deformation is remarkably different between periods of sustained high and low pressure weather systems (identified from NCAR/NCEP reanalysis and personal weather log). It is found that during low pressure the lead deformation is characterized by diurnal closing and opening, with a little shearing and periodic ridge building. In contrast, high pressure periods are characterized by diurnal opening and closing in concert with large shearing
events. From analysis of SAR images we find the synoptic time scale deformation in the coastal shear zone follows that observed at the ICEX lead. The volume of new ice produced and ridged in the ICEX lead is estimated, indicating the magnitude of ice mass produced due to tidal and inertial forcing in the Beaufort Sea seasonal ice zone. The dependence of the new ice production on the regional scale wind forcing is investigated, indicating greater ice production during atmospheric highs predominately through inertial motion. Our results show that to simulate global sea ice mass it is important to use a constitutive relation and oriented thickness distribution that represents observed lead scale deformation, and that inertial and tidal forcing should be included. Towards this goal more field data of mesoscale deformation is required.

Abstract Categories: Changes in the Sea

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