TY - JOUR
T1 - Refreezing on the Greenland ice sheet: a comparison of parameterizations
AU - Reijmer, C.H.
AU - van den Broeke, M.R.
AU - Fettweis, X.
AU - Ettema, J.
AU - Stap, L.B.
PY - 2012
Y1 - 2012
N2 - Retention and refreezing of meltwater are acknowledged
to be important processes for the mass budget
of polar glaciers and ice sheets. Several parameterizations
of these processes exist for use in energy and mass
balance models. Due to a lack of direct observations, validation
of these parameterizations is difficult. In this study
we compare a set of 6 refreezing parameterizations against
output of two Regional Climate Models (RCMs) coupled to
an energy balance snow model, the Regional Atmospheric
Climate Model (RACMO2) and the Mod`ele Atmosph´erique
R´egional (MAR), applied to the Greenland ice sheet. In
both RCMs, refreezing is explicitly calculated in a snow
model that calculates vertical profiles of temperature, density
and liquid water content. Between RACMO2 and MAR,
the ice sheet-integrated amount of refreezing differs by only
4.9mmw.e yr−1 (4.5 %), and the temporal and spatial variability
are very similar. For consistency, the parameterizations
are forced with output (surface temperature, precipitation
and melt) of the RCMs. For the ice sheet-integrated
amount of refreezing and its inter-annual variations, all parameterizations
give similar results, especially after some
tuning. However, the spatial distributions differ significantly
and the spatial correspondence between the RCMs is better
than with any of the parameterizations. Results are especially
sensitive to the choice of the depth of the thermally
active layer, which determines the cold content of the snow
in most parameterizations. These results are independent of
which RCM is used to force the parameterizations.
AB - Retention and refreezing of meltwater are acknowledged
to be important processes for the mass budget
of polar glaciers and ice sheets. Several parameterizations
of these processes exist for use in energy and mass
balance models. Due to a lack of direct observations, validation
of these parameterizations is difficult. In this study
we compare a set of 6 refreezing parameterizations against
output of two Regional Climate Models (RCMs) coupled to
an energy balance snow model, the Regional Atmospheric
Climate Model (RACMO2) and the Mod`ele Atmosph´erique
R´egional (MAR), applied to the Greenland ice sheet. In
both RCMs, refreezing is explicitly calculated in a snow
model that calculates vertical profiles of temperature, density
and liquid water content. Between RACMO2 and MAR,
the ice sheet-integrated amount of refreezing differs by only
4.9mmw.e yr−1 (4.5 %), and the temporal and spatial variability
are very similar. For consistency, the parameterizations
are forced with output (surface temperature, precipitation
and melt) of the RCMs. For the ice sheet-integrated
amount of refreezing and its inter-annual variations, all parameterizations
give similar results, especially after some
tuning. However, the spatial distributions differ significantly
and the spatial correspondence between the RCMs is better
than with any of the parameterizations. Results are especially
sensitive to the choice of the depth of the thermally
active layer, which determines the cold content of the snow
in most parameterizations. These results are independent of
which RCM is used to force the parameterizations.
U2 - 10.5194/tc-6-743-2012
DO - 10.5194/tc-6-743-2012
M3 - Article
SN - 1994-0416
VL - 6
SP - 743
EP - 762
JO - The Cryosphere
JF - The Cryosphere
ER -
