Research Applications of Westgrid: Glacier Modelling

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Research Applications of Westgrid Glacier
Modelling
Shawn Marshall University of Calgary
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Dyurgerov, 2005
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Larsen B Ice Shelf, 2002
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Science (March 2006)
Jakobshavn Isbræ, West Greenland
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Greenland summer melt zone, 1992 vs. 2002
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Scientific Applications of Westgrid
Ice Sheet and Climate Modelling
How can we address questions such as ?
the future of the Greenland and Antarctic Ice
Sheets? (i.e. sea level rise this
century) ? Climate changes of the past, e.g.
ice ages?
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Ice Sheet Models - coupled simulation of
conservation of mass, momentum, and energy
within a 3D ice mass ? Upper boundary
condition temperature, snow
accumulation ? Basal boundary condition
geothermal heat flux, topography,
subglacial geology, hydrogeology
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Ice Dynamics Governing equation
(conservation of mass)
? H
?
i,j
H ui,j
- ( ) b
? xj
? t
Ice velocity is calculated based on
a constitutive law (e.g., Glens flow law) and
the momentum (stress) balance
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3D Ice Dynamics And vertically Vertical
grid transformation, like pressure surfaces
in atmospheric modelling
surface
wi,j,k
k
z (?)
bed
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3D Ice Thermodynamics Governing equation
(conservation of energy)
? T
?
? 2T
?
- ( vkT ) ?
?c
? xk
? z2
? t
3D heat vertical strain advection
diffusion heating
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And add a coupled 3D temperature solution
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Summary Coupled 3d system of equations to
model glacier temperature, velocity, and
thickness. Introduce at something like 50-km
resolution over the continents
This in turn is coupled with ? a global
climate model ? models of subglacial geology
and hydrology ? models of isostatic rebound
(solid Earth)
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Examples
Past climate and ice sheet variability in
Greenland and North America
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Arctic Warming, Last Interglacial Period
NCAR CCSM
Otto-Bliesner et al., 2006
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Examples
The last ice age in North America
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Laurentide Ice Sheet, Last Glacial Maximum
21,000 years ago
Ice sheet elevation (m)
0 500 1000 1500 2000
2500 3000
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Laurentide Ice Sheet, Last Glacial Cycle
120,000 years ago to present
0 500 1000 1500 2000
2500 3000
z (m)
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Summary Good old-fashioned number-crunching
- non-linear solution of sparse matrices

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