Zender, C. S., Krolewski, A. G., Tosca, M. G., and Randerson, J. T.: Tropical biomass burning smoke plume size, shape, reflectance, and age based on 2001–2009 MISR imagery of Borneo, Atmos. Chem. Phys., 12, 3437-3454, doi:10.5194/acp-12-3437-2012.

Land clearing for crops, plantations and grazing results in anthropogenic burning of tropical forests and peat lands in Indonesia, where images of fire-generated aerosol plumes have been captured by the Multi-angle Imaging SpectroRadiometer (MISR) since 2001. Every year open burning rivals fossil fuel as a source of Carbon in Indonesia, while in dry years that occur during mature El Niño events, open burning in Indonesia alone can account for 30% of global fire emissions. Yet surprisingly little is known about the characteristics of the smoke plumes that annually carpet this majestic archipelago during fire season (roughly August-November). Jim Randerson’s Research Group is already assessing and accounting for global climatic impacts of land disturbances such as fires, so we decided here to focus on the plumes themselves that occupy smaller scales only resolved by satellites in the past decade. We asked what are the size, shape, optical properties, and age of distinct fire-generated plumes in Borneo from 2001-2009? The area is very dynamic with sea breezes, convection, and a late afternoon peak in anthropogenic fires. MISR images the region each day at 10:30 AM, and captures the activity like a stroboscope at a dance party. Distinguishing new from old plumes, and plumes from indistinct aerosol clouds was labor-intensive yet yielded new insights into plume evolution. We found that the local circulation stretched plumes into ovoid shapes, with large variability, and that smoke became too tenuous to visibly connect with fires after about three hours. Interestingly, these Indonesian plumes endure about three times longer, and grow nearly twice as long as smoke plumes from Central America. Why tropical fire plumes exhibit strong regional differences illustrates numerous questions that must be answered to better understand the consequences of forest management, or lack thereof, on local and regional climate and air quality. The differences we see are consistent with peat fuel loads, agricultural clearing practices, and sampling issues. We would like to leapfrog our current database of plume snapshots with continual monitoring of plumes from Asia, the Americas, and Africa. A rewarding aspect of this study was mentoring a high school student, Alex Krolewski who co-authored the work. Alex’s curiosity, eagerness, and persistence showed that research is a state of mind, which does not heed age limits.