[1] Georgia Inst Technol, Sch Earth & Atmospher Sci, Atlanta, GA 30332 USA
[2] Duke Univ, Nicholas Sch Environm, Durham, NC USA
[3] NASA, Langley Res Ctr, Div Atmospher Sci, Hampton, VA 23665 USA
[4] Drexel Univ, Dept Chem, Philadelphia, PA 19104 USA