BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Sea ice motion on extreme scales: from a floe to the continuum - S
 rikanth Toppaladoddi\, University of Leeds
DTSTART:20260123T160000Z
DTEND:20260123T170000Z
UID:TALK243382@talks.cam.ac.uk
CONTACT:Duncan Hewitt
DESCRIPTION:Arctic sea ice is one of the most sensitive components of the 
 Earth’s climate system and acts as a bellwether for the changes in it. T
 he ice cover grows\, shrinks\, and moves because of its interactions with 
 the atmosphere and the underlying ocean. One of the principal challenges a
 ssociated with modelling the atmosphere-ice-ocean interactions is the lack
  of definitive knowledge of the rheological properties of the ice cover at
  large scales. A systematic study of sea ice dynamics since the 1960s has 
 led to the development of many rheological models\, but the predictions fr
 om these models are not entirely consistent with observations.\n\nIn this 
 talk\, I will use tools from kinetic theory to obtain the continuum equati
 ons of Arctic sea ice motion starting from the dynamics of a single floe a
 nd show that the rheology that emerges from floe-floe interactions is visc
 ous — as conjectured by Reed and Campbell (J. Geophys. Res. 67(1)\, 281 
 (1962)). The motion of the floe is principally driven by the wind and ocea
 n currents and by inelastic collisions with the neighbouring floes. A mean
 -field representation of these collisions is developed\, neglecting any ch
 anges in the floe thickness due to thermal growth and mechanical deformati
 on. This mean-field representation depends on the state of the ice cover\,
  and is expressed in terms of ice concentration and mean thickness. The re
 sulting Langevin equation for the floe velocity\, or the corresponding kin
 etic equation (Kramers-Chandrasekhar equation) for its probability density
 \, provides a complete description of the floe's motion. I then use the fl
 oe-scale dynamics to obtain a continuum description of sea ice motion thro
 ugh a Chapman-Enskog analysis of the Kramers-Chandrasekhar equation. The l
 ocal equilibrium solution to the kinetic equation is found to be the Lapla
 ce distribution\, in qualitative agreement with observations. Lastly\, I w
 ill show that the results from this study resolve a conflict associated wi
 th the choice of the value of shear viscosity in previous idealised numeri
 cal studies of Arctic sea ice motion.\n
LOCATION:MR2
END:VEVENT
END:VCALENDAR