TY - CONF
T1 - Spectral Dependence of Black Carbon Absorption Enhancement on Clear Days and Biomass Burning Days
AU - Tripathi, S. N.
AU - Puthukkadan Moosakutty, Shamjad
AU - Pathak, Ravi
AU - Hallquist, M.
PY - 2013/12
Y1 - 2013/12
N2 - Among different aerosol species present in the atmosphere, absorption of light by black carbon (BC) is much higher compared to other species. The absorption by BC is dependent on its concentration, mixing state and also the wavelength of light. Internally mixed BC with other soluble species absorbs more light than that present as external mixture. We present spectral black carbon absorption measured at Kanpur, an urban site located in Indo-Gangetic Plain (IGP) during February-March 2013. Absorption coefficients of ambient aerosols are measured using Photo Acoustic Soot Spectrometer (PASS 3) at 405, 532, 781 nm. It is observed that absorption at 405 nm is always higher than that at 532 and 781 nm. It is likely that this higher absorption at 405 nm is due to the presence of light absorbing organic species (Brown Carbon). We also measured absorption of thermally denuded (300 C) particles using PASS 1, Particle Soot Absorption Photometer (PSAP) and an aethalometer at 781, 565 and 370-950 nm, respectively. Here we discuss the spectral nature of enhancement in absorption defined as the ratio of ambient absorption to the denuded absorption at respective wavelengths. At 781 nm enhancement values are in the range of 1.1 to 7.5 which decreases to 1.1-5.5 at 532 nm and 1.1-3.5 at 405 nm. Probability distribution of absorption enhancement for biomass burning and clear days shows a shift in mode to larger absorption enhancement during biomass burning events for 532 and 405 nm indicating the presence of absorbing organics during the biomass burning events. Concurrent measurements from High Resolution-Time of Flight-Aerosol Mass Spectrometer show high values of organics and other soluble species.
AB - Among different aerosol species present in the atmosphere, absorption of light by black carbon (BC) is much higher compared to other species. The absorption by BC is dependent on its concentration, mixing state and also the wavelength of light. Internally mixed BC with other soluble species absorbs more light than that present as external mixture. We present spectral black carbon absorption measured at Kanpur, an urban site located in Indo-Gangetic Plain (IGP) during February-March 2013. Absorption coefficients of ambient aerosols are measured using Photo Acoustic Soot Spectrometer (PASS 3) at 405, 532, 781 nm. It is observed that absorption at 405 nm is always higher than that at 532 and 781 nm. It is likely that this higher absorption at 405 nm is due to the presence of light absorbing organic species (Brown Carbon). We also measured absorption of thermally denuded (300 C) particles using PASS 1, Particle Soot Absorption Photometer (PSAP) and an aethalometer at 781, 565 and 370-950 nm, respectively. Here we discuss the spectral nature of enhancement in absorption defined as the ratio of ambient absorption to the denuded absorption at respective wavelengths. At 781 nm enhancement values are in the range of 1.1 to 7.5 which decreases to 1.1-5.5 at 532 nm and 1.1-3.5 at 405 nm. Probability distribution of absorption enhancement for biomass burning and clear days shows a shift in mode to larger absorption enhancement during biomass burning events for 532 and 405 nm indicating the presence of absorbing organics during the biomass burning events. Concurrent measurements from High Resolution-Time of Flight-Aerosol Mass Spectrometer show high values of organics and other soluble species.
M3 - Abstract
ER -