Formation and cycling of aerosols in the global troposphere

Aerosols are formed, evolve, and are eventually removed within the general circulation of the atmosphere. The characteristic time of many of the micro physical aerosol processes is days up to several weeks, hence longer than t he residence time of the aerosol within a typical atmospheric compartment ( e.g. the marine boundary layer, the free troposphere, etc.). Hence, to unde rstand aerosol properties, one cannot confine the discussion to such compar tments, but one needs to view aerosol microphysical phenomena within the co ntext of atmospheric dynamics that connects those compartments. This paper attempts to present an integrated microphysical and dynamical picture of th e global tropospheric aerosol system. It does so by reviewing the microphys ical processes and those elements of the general circulation that determine the size distribution and chemical composition of the aerosol, and by impl ementing both types of processes in a diagnostic model, in a 3-D global Che mical Transport Model, and in a General Circulation Model. Initial results are presented regarding the formation, transformation, and cycling of aeros ols within the global troposphere. (C) 2000 Elsevier Science Ltd. All right s reserved.