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Abstract:
A number of recent studies have suggested time-dependent parameterizations of daily temperature standard
deviation for modelling surface mass balances of ice sheets and glaciers using a temperature-index method.
These have been inferred from in-situ measurements and climate reanalysis data, which are only available on
yearly to decadal time scales. To date, the existing literature has not explored their applicability to climate
conditions that are different from those of today. This study presents an ensemble of simulations of the Greenland
Ice Sheet’s history since the Last Glacial Maximum to assess the performance of existing parameterizations of
daily temperature standard deviation on millennial time scales. To limit the influence of the uncertainties arising
from poorly constrained external and internal factors we adopt climate strategies of different complexities and a
sensitivity analysis of ice sheet model parameters. Our study reveals that previously proposed parameterizations of
daily temperature standard deviation have a limited performance during the deglaciation stage, failing to simulate
the retreat of ice masses as suggested by geological reconstructions. In contrast multiple studies that use constant
values of daily temperature standard deviation within the range of 4 to 5˚C receive support from our analysis,
implying that either the ice sheet model used is missing the fundamental physics necessary to capture complex
processes associated with rapid deglaciation or the values of daily temperature standard deviation suggested by
parameterizations based on present-day observations are too low to ensure the consistent Wisconsin-to-Holocene
ice sheet retreat.
