Frank Kauker, Cornelia Koeberle, Ruediger Gerdes, and Michael Karcher (2008)
Modeling the 20th century Arctic Ocean/Sea ice system: Reconstruction of surface forcing
Journal of Geophysical Research-Oceans 113(C9).
[1] The ability to simulate the past variability of the sea ice-ocean
system is of fundamental interest for the identification of key processes
and the evaluation of scenarios of future developments. To achieve
this goal atmospheric surface fields are reconstructed by statistical
means for the period 1900 to 1997 and applied to a coupled sea ice-ocean
model of the North Atlantic/Arctic Ocean. We devised a statistical
model using a redundancy analysis to reconstruct the atmospheric
fields. Several sets of predictor and predictand fields are used
for reconstructions on different time scales. The predictor fields
are instrumental records available as gridded or station data sets
of sea level pressure and surface air temperature. The predictands
are surface fields from the NCAR/NCEP reanalysis. Spatial patterns
are selected by maximizing predictand variance during a ``learning''
period. The reliability of these patterns is tested in a validation
period. The ensemble of reconstructions is checked for robustness
by mutual comparison and an ``optimal'' reconstruction is selected.
Results of the simulations with the sea ice-ocean model are compared
with historical sea ice extent observations for the Arctic and Nordic
Seas. The results obtained with the ``optimal'' reconstruction are
shown to be highly consistent with these historical data. An analysis
of simulated trends of the ``early 20th century warming'' and the
recent warming in the Arctic complete the manuscript.