AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Light-absorbing Organic Aerosol Emissions from Cultural Practices in South Asia: Contribution to Enhanced Regional Warming
Rajan K. Chakrabarty, Shamsh Pervez, HANS MOOSMULLER, Judith Chow, John Watson, Desert Research Institute
Abstract Number: 512 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Atmospheric heating due to carbonaceous aerosols contributes to fourfold uncertainty in climate forcing over south Asia (SA). Black (BC) and organic carbon (OC) aerosols in the atmosphere over this region alter net solar radiative flux to the Earth’s surface, the net effect of which may outweigh the regional warming effect of greenhouse gases. BC aerosols absorb sunlight in visible wavelengths, increasing inversely with wavelengths from near-infrared (1 µm) to ultraviolet with a power law of one. OC aerosols absorb sunlight insignificantly in visible wavelengths, with the exception of brown carbon – a recently identified class of OC – which strongly absorbs in the near-UV.
Current view among climate and emission inventory modelers holds that BC – emitted from fossil and biofuel-driven contained combustion sources – constitute the light-absorbing component of regional aerosols over SA. In this talk, we present our results of aerosol emissions from hitherto uninvestigated combustion sources in SA – open-air burning of funeral pyres and incense burning in temples. We found that large amounts (≈ 98% by mass) of light-absorbing OC are emitted per kilogram of feedstock burned. The emitted OC contributed to greater than 40% of visible solar radiation absorbed by the smoke plume. We calculated that these uninventoried combustion sources in SA contributed to approximately 92 gigagrams of light-absorbing OC annually, which is equivalent to ≈10% and 23% of carbonaceous aerosol mass from regional biofuels and fossil fuels, respectively. Our findings underscore the importance of accounting for cultural burning practices as aerosol sources in emission inventories and light-absorbing OC in climate models, as well as for development of mitigation strategies.