Efficient New Method for Determining Sources of Northern Hemisphere Black Carbon
The dark aerosol black carbon (BC) is a warming agent, derived from combustion of fossil fuels and wood. It survives in the atmosphere for days to weeks, before being removed by precipitation or deposition to the ground, giving it time to be transported quite some distance. By the time it leaves the atmosphere, it can be difficult to determine its origin. For some remote regions, such as the Arctic, it would be useful to know the BC source region for considering possible pollution reduction strategies and better estimating the global impacts of fossil fuel combustion on climate change. The brute force method to determine BC source regions using a chemistry-climate model involves substantial computer time. U.S. Department of Energy scientists at Pacific Northwest and Los Alamos National Laboratories used a novel application of a mathematical technique to estimate the source-receptor relationships that describe the origin of particles such as BC reaching different locations of the planet. The approach, called a “Gaussian process emulator,” reveals model transport tendencies based on a relatively small number of simulations, greatly reducing the computational burden. The emulator was applied within the Community Atmosphere Model (CAM5.1). The team found that regions are generally most vulnerable to pollution from local emissions, although Asia contributes a significant portion of the BC found in many parts of the northern hemisphere. These results demonstrate a promising method for characterizing dose-response signals in the climate system at a relatively low computational cost, and provide insights into the dynamical, physical, and chemical processes that influence aerosol transport. The technique will be useful in studies focusing on cost-effective global and regional pollution reduction strategies, and in climate change detection and attribution studies.
Ma, P.-L., J. R. Gattiker, X. Liu, and P. J. Rasch. 2013. “A Novel Approach for Determining Source-Receptor Relationships: A Case Study of Black Carbon Transport in Northern Hemisphere Winter,” Environmental Research Letters 8:024042. DOI: 10.1088/1748-9326/8/2/024042.