Dr. Welton has specialized in aerosol related research since 1994, particularly characterization of the optical and physical properties of various aerosol species. In addition, he is an expert in the use of lidar and radiometry to retrieve aerosol and cloud properties. He is also the co-chair of the World Meteorological Organization (WMO) Global Atmospheric Watch (GAW) Aerosol Lidar Observation Network (GALION).

Dr. Welton has been involved in numerous international field campaigns and co-led the development of several international research initiatives. Finally, Dr. Welton is a member of the science working group formulating the Aerosols, Clouds, and Ecosystems (ACE) mission recommended in the 2007 NRC Earth Sciences Decadal report for NASA.