1. Department of Physics; University of Toronto; Toronto Ontario Canada
2. Department of Physics and Engineering Physics; University of Saskatchewan; Saskatoon Saskatchewan Canada
3. Jet Propulsion Laboratory; California Institute of Technology; Pasadena California USA
4. Air Quality Research Division, Atmospheric Science and Technology Directorate; Science and Technology Branch, Environment Canada; Toronto Ontario Canada
5. NorthWest Research Associates; Socorro New Mexico USA
6. Department of Physics; New Mexico Institute of Mining and Technology; Socorro New Mexico USA
7. Department of Physics; University of Guelph; Guelph Ontario Canada
8. Environmental Science; Saint Mary's University; Halifax Nova Scotia Canada