1. Advanced Study Program; National Center for Atmospheric Research; Boulder Colorado USA
2. Chemistry Department; University of Colorado; Boulder Colorado USA
3. Cooperative Institute for Research in the Environmental Sciences; University of Colorado; Boulder Colorado USA
4. Centro de Ciencias de la Atmósfera; Universidad Nacional Autónoma de México; México City México
5. Mechanical Engineering Department; University of Minnesota; Minneapolis Minnesota USA
6. Atmospheric Chemistry Division; National Center for Atmospheric Research; Boulder Colorado USA