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Abstract:
Energy fluxes for polar regions are examined for two 30-yr periods,
representing the end of the twentieth and twenty-first centuries, using
data from high-resolution simulations with the ECHAM5 climate model. The
net radiation to space for the present climate agrees well with data
from the Clouds and the Earth's Radiant Energy System (CERES) over the
northern polar region but shows an underestimation in planetary albedo
for the southern polar region. This suggests there are systematic errors
in the atmospheric circulation or in the net surface energy fluxes in
the southern polar region. The simulation of the future climate is based
on the Intergovernmental Panel on Climate Change (IPCC) A1B scenario.
The total energy transport is broadly the same for the two 30-yr
periods, but there is an increase in the moist energy transport on the
order of 6 W m(-2) and a corresponding reduction in the dry static
energy. For the southern polar region the proportion of moist energy
transport is larger and the dry static energy correspondingly smaller
for both periods.
The results suggest a possible mechanism for the warming of the Arctic
that is discussed. Changes between the twentieth and twenty-first
centuries in the northern polar region show the net ocean surface
radiation flux in summer increases similar to 18 W m(-2) (24%). For the
southern polar region the response is different as there is a decrease
in surface solar radiation. It is suggested that this is caused by
changes in cloudiness associated with the poleward migration of the
storm tracks.
