NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.

These proceedings were supported by the Electric Power Research Institute through contract number RP8011-21; the Department of Energy through grant number DE-FG02-93ER61703; the National Science Foundation through grant number IBN-9211798; the National Oceanic and Atmospheric Administration, U.S. Department of Commerce through grant number NA36RG0536; and the Presidents' Committee, National Research Council.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project.