Modeling the 20th century Arctic Ocean/sea ice system: reconstruction of surface forcing

• Main Authors: Frank Kauker, Michael Karcher
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2008
• Subjects: Arctic; Arctic Ocean; Atlantic Arctic; Atlantic-Arctic; Nordic Seas; North Atlantic; Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.588.3619; http://www.clivar.org/sites/default/files/documents/wgomd/arctic_reconstruct.pdf

The ability to simulate the past variability of the sea ice-ocean system is of funda-mental 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 atmo-spheric fields. Several sets of predictor and predictand fields are used for reconstructions on different time-scales. The predictor fields are instrumental records available as grid-ded or station data sets of sea level pressure and surface air temperature. The predic-tands 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 histori-cal 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 warm-ing in the Arctic complete the manuscript. 1.