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SUMMARY:Ice shelf-ocean interactions: self-organisation and instability - 
 Daniel Goldberg (University of Edinburgh)
DTSTART:20161123T163000Z
DTEND:20161123T173000Z
UID:TALK69002@talks.cam.ac.uk
CONTACT:Poul Christoffersen
DESCRIPTION:The ice shelves bordering the Antarctic coastline play an impo
 rtant role in both the hydrography of the Southern Ocean and the mass bala
 nce and configuration of the Antarctic Ice Sheet. On the oceanographic sid
 e\, ice shelves provide a surface boundary condition that is different tha
 n either open ocean or sea ice\, with melting and freezing rates determine
 d by small-scale turbulence and shelf-scale circulation\, the latter in tu
 rn influenced by melting and freezing rates as well as ice shelf thickness
 . In some instances under-shelf processes significantly influence open-oce
 an hydrological and biogeochemical properties.\n\nOn the glaciological sid
 e\, the ice shelves control the distribution of normal stresses at the gro
 unding line\, which in turn affects ice mass flux from the continent. Thus
  ice shelves provide a pathway for the heat content of the ocean to cause 
 changes in continental ice sheets -- which in turn feeds back on circulati
 on by modifying the shape of the ice shelf cavity. In the case of rapidly-
 evolving ice shelves exposed to warm Circumpolar Deep Water\, numerical mo
 delling of such interaction presents a large challenge\, since most ocean 
 general circulation models (OGCMs) are not designed to allow for changing 
 boundaries.\n\nI will first present results from my own studies which exam
 ined such interactions using an old method of ice-ocean coupling -- an "as
 ynchronous" (or "dump-and-restart") approach\, and discuss the results of 
 the study as well as strengths and weaknesses of the asynchronous approach
  and why it is not ideal as we move forward from process modelling to glob
 al predictions of coupled ice-ocean behaviour. I will then discuss the dev
 elopment of a new\, synchronously-coupled ice sheet-ocean model\, the diff
 iculties and what is done to address them\, and some preliminary experimen
 ts with this framework\, yielding interesting results.\n\nA common theme a
 rising from the old work and new is the fact that\, from the ice sheet sta
 bility perspective\, ice shelf thinning due to melting is not solely impor
 tant close the grounding line\, as commonly thought\, and may be vitally i
 mportant to constrain and model in other regions of ice shelves commonly o
 verlooked. Luckily\, new observing platforms are being developed that may 
 enable us to do just this.
LOCATION:Scott Polar Research Institute\, main lecture theatre
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