Expanded Wavelength CAPS-Based Particle SSA Monitor

Aerosol particles affect the radiative balance of the earth directly, by scattering and absorbing solar and terrestrial radiation, and indirectly, by acting as cloud condensation nuclei. It is now recognized that the atmospheric loading of aerosols can exert an influence on the earths radiation budget comparable in magnitude with greenhouse gases. However, the uncertainties in the current understanding of aerosol direct and indirect forcing limit the ability to quantify human influences on climate change. We are developing a particle single scattering albedo monitor employing Aerodynes patented Cavity Attenuated Phase Shift technology that combines extinction and scattering measurements in one instrument with rapid time-response, and high sensitivity and accuracy. It will operate at a single wavelength which can range from the near infrared (800 nm,) to the near- ultraviolet (365 nm) region of the spectrum. A prototype version of the single scattering albedo monitor was built and its properties investigated including determining its sensitivity, time response and response to test particles as a function of particle size for a number chemical species including polystyrene latex, ammonium sulfate and nigrosin dye. Operation of the extinction component in the near infrared (780 nm) and near-ultraviolet (365 nm) was demonstrated. The Phase II will focus on designing, building and testing a commercial version of the monitor. Improvements in accuracy specifically related to the effects of particle size will be a major emphasis. The monitor will be deployed as part of extensive field measurement campaigns in conjunction with other researchers in order to assess its field worthiness, an extremely important factor in developing a market for the instrument. Commercial Applications and Other Benefits: Successful development and marketing of this monitor will yield a significant level of direct commercial sales from the atmospheric sciences and environmental pollution research and development communities. The comparatively low cost and ease of use of this sensor will allow almost routine measurement of the optical properties of atmospheric aerosols, something precluded by the cost and complexity of current instrumentation.