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SUMMARY:Using sea-ice deformation fields to constrain the mechanical stren
 gth parameters of geophysical sea ice - Bruno Tremblay (McGill University)
DTSTART:20170915T080000Z
DTEND:20170915T084000Z
UID:TALK79371@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:<span>Co-author: Amelie Bouchat		(McGill UniversityUsing sea-i
 ce deformation fields to constrain the 2 mechanical strength parameters of
  geophysical sea ice)        <br></span><span><br>We investigate the abili
 ty of viscous-plastic (VP) sea-ice models with an elliptical yield curve a
 nd normal flow rule to reproduce the shear and divergence distributions de
 rived from the RADARSAT Geophysical Processor System (RGPS). In particular
 \, we reformulate the VP elliptical rheology to allow independent changes 
 in the ice compressive\, shear and isotropic tensile strength parameters (
 P*\, S*\, T* respectively) in order to study the sensitivity of the deform
 ation distributions to changes in the ice mechanical strength parameters. 
 Our 10-km VP simulation with standard ice mechanical strength parameters P
 &lowast\;= 27.5 kNm&minus\;2 \, S&lowast\; = 6.9 kNm&minus\;2\, and T&lowa
 st\; = 0 kNm&minus\;2 (ellipse aspect ratio of e = 2) does not reproduce t
 he large shear and divergence deformations observed in the RGPS deformatio
 n fields\, and specifically lacks well-defined\, active linear kinematic f
 eatures (LKFs). Probability density functions (PDFs) for the shear and div
 ergence of are nonetheless not Gaussian. Simulations with a reduced compre
 ssive or increased shear strength are in good agreement with RGPS-derived 
 shear and divergence PDFs\, with relatively more large deformations compar
 ed to small deformations. The isotropic tensile strength of sea ice on the
  other hand does not significantly affect the shear and divergence distrib
 utions. When considering additional metrics such as the ice drift error\, 
 mean ice thickness fields\, and spatial scaling of the deformations\, our 
 results suggest that reducing the ice compressive strength is a better sol
 ution than increasing the shear strength when performing Arctic-wide simul
 ations of the sea-ice cover with the VP elliptical rheology.</span>
LOCATION:Seminar Room 1\, Newton Institute
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