Optical Properties of Complex Aerosol Particles Containing Black Carbon (Invited Presentation)

Field observations show that individual aerosol particles are a complex mixture of a wide variety of species, reflecting various sources and physico-chemical transformations that occur in the atmosphere.

Aerosols chemico-physical characteristics, such as size, shape/morphology, chemical composition and mixing are of crucial importance as they govern aerosols microphysics and radiative properties.

A theoretical description of the interaction of solar light with complex aerosol particles, with asymmetric shapes and inhomogeneous mixing, is a complex problem that often is only solved by introducing simplified assumptions about the particle shapes and mixing. However, often the uncertainties that are introduced by such practice are not known.

The appropriateness of such simplifications largely depends on the applications and the system under investigation.

During the talk, the speaker will discuss the fundamental relation between chemico-physical characteristics of BC containing aerosols particles and their optical properties. The focus will be on the effects of aggregation and internal mixing including liquid-liquid phase separation of organic and inorganic mixtures containing BC. The speaker will demonstrate that observationally constrained simulations of the interactions of light with complex particles allow to better understand the variability of the measured aerosol optical properties and to define benchmark biases due to different approximations in aerosol parametrization.