Nishit J. Shetty, Apoorva Pandey, Stephen P. Baker, Wei Min Hao, Rajan K. Chakrabarty
Year Published:

Cataloging Information

Smoke & Air Quality
Smoke Emissions
Smoke Emissions and Inventory

NRFSN number: 20188
Record updated: October 21, 2019

Recent studies have shown that organic aerosol (OA) could have a nontrivial role in atmospheric light absorption at shorter visible wavelengths. Good estimates of OA light absorption are therefore necessary to better estimate radiative forcing due to these aerosols in climate models. One of the common techniques used to measure OA light absorption is the solvent extraction technique from filter samples which involves the use of a spectrophotometer to measure bulk absorbance by the solvent-soluble organic fraction of particulate matter. Measured solvent-phase absorbance is subsequently converted to particle-phase absorption coefficient using scaling factors. The conventional view is to apply a correction factor of 2 to absorption coefficients obtained from solvent-extracted OA based on Mie calculations. The appropriate scaling factors are a function of biases due to incomplete extraction of organic carbon (OC) by solvents and size-dependent absorption properties of OA. The range for these biases along with their potential dependence on burn conditions is an unexplored area of research.


Shetty, Nishit J.; Pandey, Apoorva; Baker, Stephen; Hao, Wei Min; Chakrabarty, Rajan K. 2019. Measuring light absorption by freshly emitted organic aerosols: Optical artifacts in traditional solvent-extraction-based methods. Atmospheric Chemistry and Physics. 19(13): 8817-8830.

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