9320871 Charlson This research project is developing a methodology for in situ measurements of the climatically important optical concerned with properties which can then be applied to regionally representative sites in order to provide relevant parameters for global climate models. Our goals to characterize measurement uncertainties and to study the sources of variation in the measured parameters by intensive, observational campaigns. Aerosol optical properties will be both measured directly and predicated by Mie theory form measurements of aerosol size distribution and size-resolved chemistry. Convergence of these two approaches is required to validate the present understanding of aerosol optics and assess the accuracy of various simplifying assumptions required by the Mie calculation. Four specific tasks will be to quantify and reduce the uncertainties that presently exist in the climatically important optical properties of tropospheric aerosols; (1) develop a measurement and data analysis methodology, (2) demonstrate closure of an extended measurement set at a well-characterized, minimally- polluted marine site (Cheeka Peak), (3) demonstrate closure at different representative sites (clean and polluted marine, clean and polluted continental), and (4) deliver aerosol optical parameters to measurement and modelling communities.
