[1] Univ Colorado, NOAA, Cooperat Inst Res Environm Sci, Boulder, CO 80309 USA
[2] Univ Colorado, Dept Atmospher & Ocean Sci, Boulder, CO 80309 USA
[3] Northland Coll, Ashland, WI USA
[4] Univ Hawaii Manoa, Int Pacific Res Ctr, Honolulu, HI 96822 USA
[5] Brown Univ, Dept Geol Sci, Providence, RI 02912 USA
[6] MIT, Dept Earth Atmospher & Planetary Sci, Cambridge, MA USA