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Publisher Summary This chapter helps in measuring aerosol properties in the free troposphere and marine boundary layer of the Northeast Atlantic, in order to survey and classify the properties of the various air masses advecting to the region, which will serve as the base for the 1997 ACE-2 experiment. It provides an overview of chemical composition, size distributions, and radiative properties for both sites. European pollution is found to affect the aerosol properties in the marine boundary layer and the free troposphere of the studied area, leading to higher nonsea-salt sulfate concentration, higher scattering coefficient, higher fight absorption, and more numerous condensation cloud nuclei (CCN). Aerosol chemistry and size distribution show that clean marine air is advected to the Tenerife MBL, with interruptions due to pollution plumes from Europe. During the 1994 and 1995 campaigns, well-defined clean and polluted episodes lasted 4 to 6 days, and no more than two major pollution outbreaks reached the site in a time span of 5 weeks. The free troposphere is characterized in July by strong dust episodes (sometimes mixed with anthropogenic inputs from Europe) alternating with cleaner periods during which significant concentrations of NH4+ and SO42- are still observed. |
