NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics Branch, Code 613.3, Greenbelt, MD 20771, USA

Oak Ridge Associated Universities, NASA Postdoctoral Program, Oak Ridge, Tennessee 37831, USA

now at: Goddard Earth Sciences & Technology Center, University of Maryland, Baltimore County, Maryland, USA

NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics Branch, Code 613.3, Greenbelt, MD 20771, USA

NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics Branch, Code 613.3, Greenbelt, MD 20771, USA

NASA Goddard Space Flight Center, Global Modeling and Assimilation Office, Code 610.1, Greenbelt, MD 20771, USA

Science Systems and Applications Inc., Lanham, Maryland, USA

NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics Branch, Code 613.3, Greenbelt, MD 20771, USA

NASA Goddard Space Flight Center, Atmospheric Chemistry and Dynamics Branch, Code 613.3, Greenbelt, MD 20771, USA

University of California, 570 Rowland Hall, Irvine, CA 92697, USA

University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA

NASA Goddard Space Flight Center, Global Modeling and Assimilation Office, Code 610.1, Greenbelt, MD 20771, USA

Goddard Earth Sciences & Technology Center, University of Maryland, Baltimore County, Maryland, USA