Cloud and aerosol properties in transition zones between cloudy and clear skies

This talk will present an overview of our efforts to characterize and better understand cloud-related changes in aerosol properties as well as cloud properties in transition zones between cloudy and clear skies. These efforts primarily involved the statistical analysis of global datasets of satellite observations and ground-based measurements of shortwave spectrometers. More than half of all aerosol measurements by passive satellite instruments come from near-cloud areas, where clouds and cloud-related processes may significantly modify aerosol optical depth and particle size. Aerosol optical depth increases systematically with regional cloud amount throughout the Earth. In contrast, effective particle size can either increase or decrease with increasing cloud cover. We will also discuss the variability of cloud optical depth and droplet effective radius approaching clear skies.