Tropospheric Anthropogenic Aerosols and Climate

This project focuses on addressing three critical science issues regarding aerosol climate forcing, response, and feedback: (1) the impacts of carbonaceous mixtures on the formation and radiation of water and ice clouds in addition to the direct radiative forcing of aerosols; (2) the climate responses reflected in the changes of clouds and precipitation caused by anthropogenic aerosols through both optical-dynamical (direct) and cloud microphysical (indirect) connections; and (3) the nonlinear effects arising from the coexistence of non-uniformly distributed anthropogenic aerosols and relatively well-distributed greenhouse gases, and from the coexistence of absorbing and scattering aerosols. To address these science issues, the PI and his team will specifically improve three aspects of our aerosol-climate model: (1) the formation, physiochemical conversion, and optical properties of carbonaceous aerosols; (2) the treatment of cloud processing and recycling of carbonaceous contents through cloud and precipitation evaporation; and (3) the impacts of anthropogenic aerosols particularly carbonaceous mixtures on ice nucleation.

These improvements with designed long ensemble integrations and special sensitivity simulations would enable the study of several key but still poorly described processes in the models, and thus to better understand the climate responses to anthropogenic aerosols both through the direct and indirect effects. The model developed by this program will be provided to the community after the completion of the project, as a unique option to the current CESM aerosol models, for conducting climate response/feedback study with a size- and mixing state-dependent aerosol representation and a good computationally efficiency. Thus the broader impacts of the project are high.