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SUMMARY:Multiscale analysis of sea ice - a partially melted\, polycrystall
 ine composite material - Ken Golden (University of Utah)
DTSTART:20160411T150000Z
DTEND:20160411T160000Z
UID:TALK65391@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Earth&#39\;s sea ice packs are key players in the climate syst
 em and critical indicators of climate change\, as evidenced by the recent 
 precipitous losses of summer Arctic sea ice. As a material\, frozen sea wa
 ter is a polycrystalline composite of a pure ice matrix containing brine i
 nclusions - the melt phase - whose volume fraction and connectivity depend
  strongly on temperature. The brine phase undergoes a percolation threshol
 d at a critical temperature where the inclusions coalesce to form channels
  through which the melt phase can flow. Fluid transport through sea ice me
 diates key climatological and biological processes\, and can enhance therm
 al transport via convection in the porous microstructure.&nbsp\;<br><br>Du
 ring the Arctic melt season\, the sea ice surface is transformed from vast
  expanses of snow covered ice to complex mosaics of ice and melt ponds. Se
 a ice albedo\, a key parameter in climate modeling\, is largely determined
  by melt pond evolution. As the ponds grow and coalesce\, the melt phase u
 ndergoes a percolation threshold and the fractal dimension of the pond bou
 ndaries transitions from 1 to about 2 around a critical pond size.&nbsp\;<
 br><br>In the two lectures\, I will discuss mathematical models of composi
 te materials and statistical physics that we have been using to describe t
 he effective fluid\, thermal\, and electromagnetic transport properties of
  sea ice\, and to address other problems in sea ice physics such as melt p
 ond evolution. I will cover a range of mathematical techniques\, some of w
 hich may possibly shed light on similar questions for partially molten roc
 k. They include percolation theory\, multiscale homogenization\, integral 
 representations for effective transport coefficients of composite media\, 
 spectral measures and random matrix theory\, homogenization for advection 
 diffusion processes\, and Ising models. These models have been developed i
 n conjunction with our field experiments in the Arctic and Antarctic. A sh
 ort video on a recent Antarctic expedition will be shown.
LOCATION:Seminar Room 1\, Newton Institute
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