Current research directions of the Nenes group include:  (1) Regional and global modeling of aerosols and clouds, (2) Modeling and parameterization of cloud microphysical processes, (3) Thermodynamic modeling of tropospheric aerosols, (4) Instrumentation and techniques for characterizing organic-water interactions, hygroscopicitiy and CCN activity of aerosols, (5) Laboratory and field studies on CCN activity and aerosol-cloud interactions, (6) New particle formation and its impact on CCN concentrations, (7) Effect of pollution on marine ecosystem productivity and carbon cycle, (8) Impact of marine ecosystem productivity on clouds.