[1] Roger Williams Univ, Dept Environm Sci, Bristol, RI 02809 USA
[2] Penn State Univ, Dept Meteorol, University Pk, PA 16802 USA
[3] Penn State Univ, Earth & Environm Syst Inst, University Pk, PA 16802 USA
[4] Alfred Univ, Dept Environm Studies, Alfred, NY 14802 USA
[5] Natl Ctr Atmospher Res, Climate Global Dynam Div, Boulder, CO 80305 USA