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Arthur J. Sedlacek III Brookhaven National Laboratory Atmospheric Sciences Division Bldg. 815E, 75 Rutherford Drive Upton, NY 11973-5000 Tel: 631-344-2404 Fax: 631-344-2887 email: sedlacek@bnl.gov One of the central goals in the community is to better quantify the individual roles that aerosol absorption and scattering have on radiative balance. However, despite focused work on this issue, significant discrepancies on aerosol absorption still exist between measurements inferred from remote sensing and those obtained by in situ techniques. This is due, in large part, to the simple fact that the scattering channel dominates aerosol extinction and, thereby, makes measurement of the absorption difficult. An alternative method to measuring aerosol absorption is proposed herein: Measurement of the thermal dissipation of the spectrally absorbed energy through interferometry. The use of this coherent optical detection technique is particularly well suited to measuring the refractive index change that accompanies this energy transfer process. The primary goal of this project is to conduct in situ measurements of aerosol absorption during Atmospheric Sciences Program (ASP) field campaigns. To meet this goal, construction of a prototype system will be undertaken to gain experience with the technique, characterize the sensitivity, and develop calibration. In addition to these activities, comparisons will be made with the filter-based technique [e.g., Particle Soot Absorption Photometer (PSAP)] and with other in situ instruments [Cavity Ringdown (CRD) and photoacoustic spectroscopy] both in the laboratory and in the field. It is envisioned that this instrument will find utility in a laboratory setting for measuring fundamental optical properties of prepared (well-characterized) aerosols, as a potential calibration tool for the widely-used PSAP method and as a fieldable instrument in ASP field studies. Keywords: photothermal; interferometry; aerosol absorption; single scattering albedo [back to ASP ST Membership] |