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SUMMARY:Calving Laws for Ice Sheet Models - Recent Progress and Future Pro
 spects - Douglas Benn (University Centre in Svalbard and the University of
  St. Andrews)
DTSTART:20101117T163000Z
DTEND:20101117T173000Z
UID:TALK26819@talks.cam.ac.uk
CONTACT:Poul Christoffersen
DESCRIPTION:Calving accounts for most ice losses from the Antarctic Ice Sh
 eet\, around half of the losses from the Greenland Ice Sheet\, and a subst
 antial amount of the ablation from many high-latitude glaciers and ice cap
 s. Despite this\, calving processes are still poorly represented in progno
 stic ice sheet models\, limiting our ability to predict ice-sheet response
  to climate change. A new approach to quantifying calving losses has been 
 developed\, based on the depth of penetration of surface crevasses\, which
  in turn is a function of the velocity field near the glacier margin. The 
 potential of this new approach has been demonstrated in two recent papers\
 , which incorporate crevasse-depth calving laws (CDCLs) in glacier models.
  First\, Nick et al. (2010) conducted a series of experiments with a highe
 r-order flow-line model\, and showed that CDCLs allow a much broader range
  of glacier behaviour than other ‘calving laws’. Second\, Otero et al.
  (2009) used a static\, three-dimensional\, higher-order model to successf
 ully predict the calving front position of a small Antarctic glacier. Whil
 e the success of these implementations is very encouraging\, the incorpora
 tion of CDCLs in a time-evolving\, three-dimensional higher-order model re
 mains an important goal for the future.\n\nFuture development of calving m
 odels requires both systematic observations of calving margins and improve
 d modeling routines. Empirical data are urgently needed to determine how w
 ell models represent real calving processes and ice-front behaviour\, and 
 to identify key areas where improvements are needed. Many issues remain wi
 th modeling calving glaciers\, but perhaps the most fundamental challenge 
 is to find robust methods of incorporating basal motion (sliding) in highe
 r-order models. It is clear that there are intimate links between calving 
 and glacier dynamics\, but realistic\, workable ‘sliding laws’ remain 
 elusive. This problem is closely linked with another of glaciology’s ‘
 last great problems’ – the calculation of evolving subglacial water-pr
 essure fields.
LOCATION:Scott Polar Research Institute\, main lecture theatre
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