A Multi-satellite Analysis of Fire Smoke Impacts in Colorado Over the Last Decade
M.V. Martin1, C.L. Heald2, B. Ford1, A.J. Prenni1 and C. Wiedinmyer3
1Colorado State University, Department of Atmospheric Science, Fort Collins, CO 80523; 970-491-8286, E-mail: firstname.lastname@example.org
2Massachusetts Institute of Technology, Department of Civil and Environmental Engineering/Department of Earth, Atmospheric, and Planetary Sciences, Cambridge, MA 02139
3National Center for Atmospheric Research, Boulder, CO 80307
We present an analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) Aerosol Optical Depth (AOD) in combination with surface PM2.5 (Particulate Matter) to investigate the impact of fires on aerosol loading and air quality over Colorado from 2000 to 2012, and to evaluate the contribution of local versus transported smoke. Fire smoke contributed significantly to the AOD levels observed over Colorado. During the worst fire seasons of 2002 and 2012, average MODIS AOD over the Colorado Front Range corridor were 20–50% larger than the other 11 years studied. Surface PM2.5 was also unusually elevated during fire events, reaching locally unhealthy levels (>100 µg/m3) over populated areas during the 2012 High Park fire and the 2002 Hayman fire. Over the 13 years examined, long-range transport of smoke from the northwestern U.S. and even California (>1500 km distance) occurred often and affected AOD (Figure 1) and surface PM2.5. During most of the transport events, MODIS AOD and surface PM2.5 were reasonable correlated (r2=0.2–0.9), indicating that smoke subsided into the Colorado boundary layer and reached surface levels. However, that is not always the case since at least one event of AOD enhancement was disconnected from the surface (r2 < 0.01 and low PM2.5 levels). Observed plume heights from Multi-angle Imaging SpectroRadiometer satellite instrument and Cloud-Aerosol Lidar with Orthogonal Polarization vertical aerosol profiles showed a complex vertical distribution of smoke emitted by the High Park fire in 2012. Smoke was detected from a range of 1.5 to 7.5 km altitude at the fire origin and from ground levels to 12.3 km altitude far away from the source. The variability of smoke altitude as well as the local meteorology were key in determining the aerosol loading and air quality over the Colorado Front Range region. Our results underline the importance of accurate characterization of the vertical distribution of smoke for estimating the air quality degradation associated with fire activity and its link to human health.