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SUMMARY:Multiscale analysis of sea ice - a partially melted\, polycrystall
 ine composite material - Ken Golden (University of Utah)
DTSTART:20160411T133000Z
DTEND:20160411T143000Z
UID:TALK65390@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 
 water is a polycrystalline  composite of a pure ice matrix containing brin
 e inclusions - the melt phase -  whose volume fraction and connectivity de
 pend strongly on temperature. The brine  phase undergoes a percolation thr
 eshold at a critical temperature where the  inclusions coalesce to form ch
 annels through which the melt phase can flow.  Fluid transport through sea
  ice mediates key climatological and biological  processes\, and can enhan
 ce thermal transport via convection in the porous  microstructure. <br> <b
 r>During the Arctic melt season\, the sea ice surface is transformed from 
 vast  expanses of snow covered ice to complex mosaics of ice and melt pond
 s. Sea ice  albedo\, a key parameter in climate modeling\, is largely dete
 rmined by melt pond  evolution. As the ponds grow and coalesce\, the melt 
 phase undergoes a  percolation threshold and the fractal dimension of the 
 pond boundaries  transitions from 1 to about 2 around a critical pond size
 . <br> <span><br>In the two lectures\, I will discuss mathematical models 
 of composite  materials and statistical physics that we have been using to
  describe the  effective fluid\, thermal\, and electromagnetic transport p
 roperties of sea ice\,  and to address other problems in sea ice physics s
 uch as melt pond evolution. I  will cover a range of mathematical techniqu
 es\, some of which may possibly shed  light on similar questions for parti
 ally molten rock. They include percolation  theory\, multiscale homogeniza
 tion\, integral representations for effective  transport coefficients of c
 omposite media\, spectral measures and random matrix  theory\, homogenizat
 ion for advection diffusion processes\, and Ising models.  These models ha
 ve been developed in conjunction with our field experiments in  the Arctic
  and Antarctic. A short video on a recent Antarctic expedition will be  sh
 own.</span>
LOCATION:Seminar Room 1\, Newton Institute
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