Airborne Experiments to Characterize the Emissions of Biomass Burning in Mexico
Biomass burning is the largest source of primary, fine carbonaceous particles and the second largest source of trace gases in the global atmosphere. Emissions from biomass burning have a significant impact on air quality, atmospheric composition, and climate. Mexico has a high diversity of ecosystems and fire types. Emissions from biomass burning in Mexico can impact the Mexico City Metropolitan Area, which is one of the world’s largest megacities and suffers from severe air pollution, and the southern U.S. However, little was known about the chemical composition or intensity of emissions from the various types of biomass fires that occur in Mexico; thus, making it difficult to assess the impact of these fires on air pollution.
In March 2006, a multi-institution research team deployed atmospheric chemistry instruments on a U.S. Forest Service Twin Otter aircraft as part of the large, multi-aircraft MILAGRO (Megacity Initiative Local and Global Research Observations) research campaign. In addition to RMRS scientists, the research team, led by Prof. Bob Yokelson from the University of Montana, included researchers from The University of Colorado, Arizona State University, and Miami University. The team measured emissions from 56 biomass fires in central and southern Mexico. The fires studied included crop residue, tropical dry forest deforestation slash, pine-oak forests, tropical dry forests, and savannas.
The experiments provided the first detailed measurements of open biomass burning emissions in Mexico and the Northern Hemisphere Tropics. The study identified fires in central Mexico as an important contributor (up to 75%) to primary fine particle mass in the Mexico City area.
Because emissions from biomass burning in Mexico can influence the March – May air quality in the southern U.S., this study benefits U.S. air shed regulators who must consider cross-border pollution when devising air management strategies. The extensive dataset obtained in the field campaign has been integrated into two widely used global biomass mass burning emission inventories (Fire Inventory from NCAR (FINN) and version 3 of the global Fire Emissions Database (GFED3)). The dataset is being used in a current research project to improve biomass burning emissions in the National Oceanic and Atmospheric Administration’s CarbonTracker, an advanced decision support system for policy makers, industry, and scientists that keeps track of carbon dioxide uptake and release at the Earth's surface over time.