J1.2
A century-long context for South Cascade Glacier mass balance
Faron Scheffer Anslow, University of British Columbia, Vancouver, BC, Canada; and P. U. Clark and S. W. Hostetler
In order to accurately predict the changes in glacier mass balance that will occur under a
changing climate, the ability to couple detailed models of the atmosphere with glacier
mass balance models is of great importance. The mass balance time series measured on
South Cascade Glacier (SCG) for the years 1959-2003 has been modeled using a
physically based surface energy balance model driven by the RegCM, regional climate
model output with NCEP/NCAR reanalysis data as a boundary condition. We further
extend the SCG mass balance record to the beginning of the 20th century by driving our
model with data derived from the CRU TS2.1 gridded surface climatology. Physical
parameters used in the surface energy balance model were tuned to best replicate the
measured time series of mass balance components. The RegCM net balance result
correlates with measurement with r = 0.75. Performance for the winter and summer
balance components is poorer with r = 0.74 and r = 0.50. Performance using the CRU
data set is slightly better with respective correlations of 0.78, 0.72, 0.55. Our year 1902
onward results show that the greatest rates of mass loss occurred early in the century.
This rapid ablation is accompanied by low winter balance, and warm summer
temperatures. Retreat over the past decade has been accompanied by moderate to high
winter precipitation underscoring the importance of temperature in the current mass loss.
The noted recent decoupling between Pacific Ocean conditions and SCG mass balance is
replicated in our simulations; however, the earlier record of mass balance has shown
similar behavior. The tightest coupling between oceanic conditions and South Cascade
Glacier was in the middle part of the 20th century.
Recorded presentationJoint Session 1, Mountain Climatology I
Tuesday, 12 August 2008, 1:30 PM-3:00 PM, Rainbow Theatre
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