We gratefully acknowledge the help of the MIT GCM team: Alistair Adcroft, Curtis Heisey, Chris Hill, John Marshall, and Lev Perelman. This study benefited from discussions with our colleagues Ichiro Fukumori, Jochem Marotzke, and Detlef Stammer. We thank Bert Semtner and Bob Chervin for making their model output available. Financial support was provided by SERDP/DARPA as part of the ATOC project (University of California SIO Contract PO#10037358) and by NASA Grant NAGW 1048. This work was also supported by grants of HPC time from Project SCOUT at MIT-LCS (DARPA Contract MDA972-92-J-1032), from the Arctic Region Supercomputing Center, and from the Scientific Computing Division of the National Center for Atmospheric Research.
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