A new portable polar nephelometer with angularly resolved light intensity detection for the determination of Mie scattering of aerosol particles

The interaction of solar radiation with atmospheric aerosol particles has an important, yet poorly understood, effect on Earth's radiation balance. Indeed it is unclear whether certain particles provide a net warming or cooling effect on Earth's climate. Also, atmospheric particles can alter visibility in the atmosphere, particularly in urban areas and the optical properties of aerosol particles need to be better understood for remote sensing studies of the atmosphere. This thesis presents a novel, miniaturized, field deployable polar nephelometer for the measurement of the scattering properties of atmospheric aerosol particles. The instrument collects light scattered from an aerosol using an elliptical mirror and charge-coupled device (CCD) camera. The nephelometer measures angular scattering intensity (phase function) and degree of linear polarization across an angle range of 200 - 155 degrees at a resolution as high as 0.31 - 0.59 degrees per pixel, a better resolution than previous instruments. The efficacy of the instrument was confirmed by laboratory measurements of the scattering properties of various sizes of polystyrene latex (PSL) microspheres at a wavelength of 532 nm. The simplicity of the design, relatively low cost, and ability to measure multiple angles simultaneously makes this instrument an improvement over other, more complicated devices. The design can potentially be adapted to future ground and aircraft-based studies of anthropogenic and naturally occurring atmospheric particles.