School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA

School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA

School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA

Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA

Department of Atmospheric and Oceanic Sciences, Laboratory for Climate and Ocean-Atmosphere Studies, School of Physics, Peking University, Beijing, China

Department of Earth System Science, University of California, Irvine, CA, USA

Air Resources Division, National Park Service, Fort Collins, CO, USA

Air Resources Division, National Park Service, Denver, CO, USA

Air Resources Division, National Park Service, Denver, CO, USA

USDA Forest Service, University of Vermont Aiken Center, Burlington, VT, USA

Office of Air and Radiation, United States Environmental Protection Agency, Washington, DC, USA