Connecting the Radiative Influences of Aerosol upon the Mass Flux Profiles of Shallow Cumuli across the Central Atlantic Ocean Basin and its Boundaries

Principal Investigator(s):
Mark Miller, Rutgers, The State University of New Jersey

Allison Collow, Universities Space Research Association

The Atlantic Ocean covers approximately 25% of Earth’s surface and the atmosphere above it is home to a complex array of clouds and aerosols that have important influences on regional and global weather and climate.  These influences must be accurately depicted in short range, medium range, seasonal, and climate forecast models.  Conditions over the tropical Atlantic are particularly complex due to continental scale plumes of dust from the Sahara Desert and smoke from agricultural burning in Africa that drift across the Atlantic Ocean basin toward the Americas. These plumes are often initially found meandering in the lower atmosphere above shallow tropical clouds that form above the ocean surface, presumably mingling with these clouds on occasion due to convective mixing processes.  Elevated dust and smoke particles absorb incoming sunlight and substantially warm the marine atmosphere in the layer in which they are present.  This warming may alter the thermal stability of the marine atmosphere and may throttle or enhance the development of clouds, change their internal structure and the rate at which they precipitate, or isolate the lower atmosphere from drier layers above enabling water vapor to accumulate near the ocean surface potentially leading to the development of deeper convection.  This study uses observations collected using the Atmospheric Radiation Measurement program’s Mobile Facility #1 (AMF1), which was located at Ascension Island in southeastern central Atlantic for a one-year period, in concert with assimilated data from satellites, ships, and, when possible, research aircraft.  Ascension Island is immediately downwind from an African source of these plumes, but far enough removed to enable the lower atmosphere to have reacted to their presence.  Results of this study are expected to show how these dust and smoke plumes impact the moisture budget, cloud development, and cloud organization over the tropical Atlantic Ocean, and how to best represent these impacts in models.