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  • Uotila, P, A.H. Lynch, J.J. Cassano, and R.I. Cullather, Changes in Antarctic net precipitation in the 21st century based on IPCC model scenarios. J Geophys Res. In press.

Projections from fifteen global climate models and two re-analysis
products (NCEP/NCAR and ERA40) were utilised to project changes in the
net precipitation (P − E) over the Southern Ocean and Antarctica during
the twenty-first century. Three time periods, 1979-2000, 2046-2055 and 2091-
2100, of data were compared. The P − E was related to a classification of
synoptic circulation patterns obtained using a neural network algorithm known
as Self-Organising Maps (SOMs). SOM classification was successfully used
as a quality control tool to assess the simulated atmospheric circulation and
model performance in P − E.

The models predicted an increase of Antarctic P−E that averages 0.420.01
mm yr−1 for the coming hundred years based on the difference between 1979-
2000 and 2091-2100. P −E changes of individual models ranged from 0.02
to 0.71 mm yr−1. P −E integrated over the entire Antarctic ice sheet was
forecast to increase more quickly from the end of twentieth century until 2046-
2055 than from 2046-2055 until 2091-2100. Contributions to the predicted
change in P−E were evaluated for both thermodynamic and dynamic processes.
The projected change in Antarctic P−E was primarily due to thermodynamic
changes rather than circulation changes. The dynamic component
of P − E change, associated with the circulation, was important at
sub-continental scales, especially over the coastal regions. The role of dynamic
changes was maintained until the end of the twenty-first century. Intermodel
variation in predicted P − E changes and differences between models and
re-analyses in twentieth century simulations severely restrict the reliability
of these projections and highlighted need for improved polar simulations in
climate models.


Last Updated: 2007-03-01

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