Calibration of a Cavity Ring Down Spectrometry and Nephelometry Setup for Measuring Aerosol Optical Properties

Abstract:

Aerosols have a great impact on climate and global warming which is not yet fully understood. We want to have a better understanding how of how the optical properties of biomass burning aerosols, coming from cooking and forest wildfires, interact with light and affect the Earths radiation budget and its impact on climate. Cavity Ring-Down Spectrometry and integrating Nephelometry was used to determine the extinction of scattering and absorbing polystyrene latex (PSL) spheres of 390 nm and 404nm respectfully and a soot sample of 400 nm. The extinction coefficients obtained for the scattering 404 nm PSL spheres, 390 nm absorbing PSL spheres and the soot sample were: 1.337E-05 m^-1, 9.569E-05 m^-1, and 2.200E-05 m^-1 respectively. The Single Scattering Albedo was also obtained for the lab standards, which were 0.7077 for the scattering PSL spheres and 0.0643 for the absorbing PSL spheres. Samples for the flaming stage and smoldering stage were observed under a Scanning Electron Microscope (SEM) to study how their morphology varies from one stage to the other. We determined the soot sample can attenuate light but less than what our PSL spheres are capable of after comparing extinction cross-sections. Error correlations need to be determined for the 400 nm soot particles and be applied to our data. Lastly, different morphologies were observed for the two burning stages analyzed under the SEM.