Versatile Instrument for Broadband Measurements of Aerosol Extinction and Absorption

Aerosols play critical roles in the atmosphere influencing, for example, visibility, air quality, and radiative forcing. The heat balance is largely determined by aerosol optical properties and databases of these properties are used as inputs to climate models. For both laboratory and field research, there is a pressing need for high-sensitivity instruments allowing measurement of aerosol optical properties over a broad wavelength range. We will employ cavity enhanced spectroscopy and modulated photoacoustic spectroscopy (PAS) for broadband measurement of spectral aerosol extinction and absorption coefficients, respectively. Knowing extinction and absorption values allows determination of scattering (from the difference) and of albedo. In Phase I, we will show feasibility of a future field instrument allowing, for the first time, high-sensitivity broadband (100s of wavelength channels) measurements of both aerosol extinction and absorption.Commercial Application and other Benefits: Currently there are very limited commercial offerings for sensitive optical measurements of aerosols. In comparison to available products, the proposed instrument offers broadband operation, i.e. hundreds of wavelength channels as opposed to one (or up to three). Commercialization of the proposed instrument will therefore be of strong benefit to the atmospheric science community (university, government, industry). We have support letters from two instrument manufacturers showing their interest in our instrument.