[1] Pacific NW Natl Lab, Atmospher Sci & Global Change Div, Richland, WA 99352 USA
[2] Univ Maryland, NASA, Goddard Space Flight Ctr, Goddard Earth Sci & Technol Ctr, Greenbelt, MD 20771 USA
[3] NASA, Goddard Space Flight Ctr, Atmospher & Space Phys Lab, Greenbelt, MD 20771 USA
[4] Texas A&M Univ, Dept Atmospher Sci, College Stn, TX 77843 USA