Anthony W. Strawa and Rudolf F. Pueschel

Aerosol optical properties are extremely important in assessing climate change. Our lack of sufficient knowledge of aerosol optical properties and their variability in the atmosphere have led the Intergovernmental Panel on Climate Change (IPPC) to rate the effect of aerosol as the most uncertain of all parameters considered important to climate change. Currently, these aerosol properties are obtained from filter samples that measure absorption of black carbon aerosols on a time scale of tens of minutes to hours. Aerosol variability causes significant changes in optical properties on the order of seconds, especially when sampled from aircraft. Thus, the research community is very interested in an instrument that can measure the optical properties of all aerosols, not just black carbon, on a time scale of seconds. The instrument developed by Informed Diagnostics, Inc. can meet these expectations and has the capability to revolutionize the measurement of aerosol optical properties.

The Cloud and Microphysics Group at Ames is working with Informed Diagnostics, Inc. to develop an innovative instrument using cavity ringdown spectroscopy (CRDS) to measure the extinction and scattering coefficients of aerosol and consequently the single-scatter albedo. The prototype instrument demonstrates 1) fast and accurate measurement of aerosol extinction, 2) measurement of aerosol scattering in a CRDS system, and 3) simultaneous measurement at two laser wavelengths. The instrument proved capable of measuring the extinction of ammonium sulfate aerosol typical of the mid- to high-troposphere background aerosol. At the same time the scattering of the aerosol was measured, and an estimate of its single-scatter albedo could be made. We expect continued development of this technology will lead to a flight-ready instrument within the next two years.

Collaborator: T. Owano, Informed Diagnostics, Inc.

Point of Contact: Anthony W. Strawa, (650) 604-3437, astrawa@mail.arc.nasa.gov