Current research interests are focused on two major themes - the individual particle analysis of atmospheric particles using electron microscopy and the determination of aerosol optical/radiative properties and their effects on climate forcing. Specific research in these areas includes the individual particle analysis of remote area aerosols and aircraft emissions, the building and maintenance of an aerosol climatology database of particle types found at various locations and altitudes around the globe, measurement of the spatial and temporal variability of aerosol optical properties from ground stations and research aircraft and their effects on climate forcing, and investigation of the dependence of aerosol radiative properties on relative humidity.