Towards a microstructure based flow law of ice

Nuuk, Greenland 21-26 August 2011

INTRODUCTION

During the last 20 years more than 10 deep ice cores have been drilled in Greenland and Antarctica providing an overwhelming amount of new information  about the evolution of the microstructure in the ice sheets. The workshop brings together scientists working about the evolution of the microstructure in ice cores with others modelling ice sheet flow to develop strategies how to formulate a microstructure based flow law of ice.

MOTIVATION

More than 20 years ago R. Alley formulated flow law hypotheses based on conclusions drawn from results obtained from the first deep ice cores drilled before 1990. Since then 10 deep cores were drilled in Greenland and Antarctica (GRIP, GISP2, NGRIP, NEEM, EDC, EDML, Dome Fuji, Vostok, Talos Dome and WAIS divide). During the last 10 years digital imaging techniques provide an overwhelming amount of new information about the evolution of the microstructure. Slip bands, subgrain boundaries and grain boundaries have been mapped on along several cores. The orientation of c-axes is determined by automated fabric analyzers in high resolution. γ diffraction and SEM-EBSP methods have been introduced in ice core research and provide the complete axes information (a- and c-axis). In combination with optical mapping there is access to deformation and recrystallization on the grain scale. Computer power increased dramatically. On standard computers ice sheet models run which needed expensive super computing power 10-20 years ago. Both, new data and computing power offer the possibility to implement recrystallization or the evolution of c-axes in flow models to better specify the viscosity of ice. A grain-size dependent flow is still questioned although evidence from various directions seem to argue for.

After 20 years it is time to recapitulate the flow law hypotheses proposed by Richard Alley.This workshop intends to bring together a small group of experts with different background summarize the present state in the different fields and to develop strategies how the new information about the evolution of the microstructure in an ice sheet can be used to formulate a mcirostructure based flow law.

There are many good reasons to do so. Most uncertainty in sea level projections in the expected warmer future results from the ice sheets. Mass balance contribute to the uncertainties but also the flow behavior of the ice sheets in many respects.

PROGRAM

Sunday 21st Arrival, ice breaker
Monday 22nd workshop
Tuesday 23rd workshop
Wednesday 24th Excursion by ship to the Nuuk glaciers
Thursday 25th workshop
Friday 26th Departure

ORANIZERS

Dorthe Dahl-Jensen, Copenhagen (ddj@gfy.ku.dk and neem-camp@gfy.ku.dk)

Sepp Kipfstuhl, Bremerhaven  (Sepp.Kipfstuhl@awi.de)

INFORMATION, ACCOMMODATION & COSTS

Nuuk can be reached from Copenhagen by Air Greenland (www.airgreenland.com). The meeting will be held at the Greenland Climate Research Center (GCRC) at the Greenland Institute of Natural Resources (www.natur.gl). Housing has been pre-booked at the Greenland Institute of Natural Resources Annex (www.natur.gl/en/the-institute/scientific-infrastructure/). The daily rate for staying overnight is 300 dk kr. It is possible to extend your stay to Monday August 29th if you wish to spend a weekend as a tourist in Greenland. Cost of travel, housing need to be covered by the participants as well as the workshop fee of 1000 dk kr covering meeting room, lunches, excursion and ice breaker. Funds are available to support 1-2 participants so please let the organizers know if you are in need.

Short:

Accommodation: 300 dk kr / night
Workshop fee: 1000 dk kr

REGISTRATION

  • Let Dorthe (ddj@gfy.ku.dk and neem-camp@gfy.ku.dk) and Sepp (Sepp.Kipfstuhl@awi.de) know as soon as possible if you can participate.
  • Send title(s) for informal presentations and subjects for discussions to Dorthe and Sepp.
  • Order you air ticket to Greenland (Air Greenland)
  • The faster you let us know if you can participate the better. A compiled list of participants and further information will be sent around July 15 so please react before this deadline.

FUNDING