Some Characteristics of the Antarctic Aerosol
Aerosol concentrations have been systematically measured at the South Pole for five years. These climatological measurements have been supported by vertical and horizontal profiles obtained in summer with aircraft flights. Aerosol size data has been obtained with diffusion batteries, electrostatic precipitators, and cascade impactors.
There is a strong (5 to 1) seasonal variation in surface aerosol concentrations, with the maximum aerosol concentration generally occurring with the beginning of summer mixing in November. Vertical profiles consistently show the greatest aerosol concentrations to occur in the moist layer, a few hundred meters above the surface, and then diminishing quite steadily with altitude.
Examination of collected particles by light and electron microscopy shows them to be soluble, with refractive index of ~1.54 and often with the appearance of flattened drops. The maximum particle radius found was 3 µm and the peak volume concentration occurred at 2 µm radius. The size distributions are of similar slope to those measured over the Weddell Sea by Meszaros and in Tasmania by Bigg. We interpret this as evidence that the Southern Ocean and especially the Weddell Sea as the source of these particles. The particles arriving at the station are then quite probably the residue of evaporated clouds, and the aerosol is representative of that occurring at the end point of many of nature’s particle removal mechanisms.
KeywordsSouthern Ocean Aerosol Concentration Cascade Impactor Electrostatic Precipitator Solution Drop
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