1. National Park Service, Air Resources Division, Lakewood, Colorado, USA
2. Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
3. Cooperative Institute for Research in the Atmosphere (CIRA), Colorado State University, Fort Collins, Colorado, USA
4. Analytical Sciences, RTI International, Research Triangle Park, North Carolina, USA
5. University of California, Davis, Air Quality Research Center, Davis, California, USA
6. Dinosaur National Monument, Dinosaur, Colorado, USA