Microphysical and radiative evolution of aerosol plumes over the tropical North Atlantic ocean

• Main Authors: Timothy J. Garrett, Lynn M. Russell, V. Ramaswamy, Steven F. Maria, Barry J. Huebert
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2002
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.664.2703; http://aerosols.ucsd.edu/papers/Garrett2003jgr.pdf

[1] Over the tropical North Atlantic Ocean in the summer, plumes of aerosol extend from Saharan Africa to the Caribbean. The microphysical and radiative evolution of such plumes is studied using a Lagrangian column model and measurements obtained near the west coast of Africa (during the second Aerosol Characterization Experiment [ACE-2]) and the Caribbean Sea (during the Passing Efficiency of the Low Turbulence Inlet [PELTI] experiment). Mass and scattering in the plumes can be separated into two layers that overlay one another over much of the Atlantic Ocean. Mineral dust dominates in the lower free troposphere, and sea-salt aerosol dominates in the boundary layer. Carbonaceous, sulfate, and nitrate (CSN) aerosols are a minor component of mass but contribute significantly to total column optical depth. Combined, CSN aerosols and sea-salt contribute to more than half of total aerosol clear-sky shortwave forcing associated with such plumes. Satellite and model data suggest that the reduction of plume forcing between the African coastline and the Caribbean is less than 20%. The reduction is due principally to settling of large dust particles and atmospheric subsidence; however, the reduction of forcing remains small because (a) boundary layer trade winds provide a