[1] Dalhousie Univ, Dept Oceanog, Halifax, NS B3H 4J1, Canada
[2] Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA
[3] Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA
[4] Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08901 USA