1. a Institute of Ocean Sciences , P.O. Box 6000, 9860 West Saanich Road, Sidney , BC , V8L 4B2 E-mail:
2. b Institute of Ocean Sciences , P.O. Box 6000, 9860 West Saanich Road, Sidney , BC , V8L 4B2
3. c Department of Atmospheric Sciences , University of Washington
4. d School of Oceanography , University of Washington