Beginning in 1992 and continuing through the present he has carried out instrument calibration and deployment, field experimentation, data analysis, and scientific research within the global Aerosol Robotic Network (AERONET) project. He has authored and co-authored over 110 papers in the refereed literature with recent emphasis on studies of the optical properties of atmospheric aerosols, in particular from biomass burning, fossil fuel combustion, coarse-fine mode mixtures, also aerosol modification by cloud processing and the attenuation of solar flux by aerosols. Research Interests Atmospheric Aerosol Remote Sensing - Involved in ground-based remote sensing of aerosol optical properties with the AERONET network