CHEMICAL APPORTIONMENT OF AEROSOL COLUMN OPTICAL DEPTH OFF THE MID-ATLANTIC COAST OF THE UNITED-STATES

Aerosol column optical depths derived from airborne Sun photometer and in situ measurements of aerosol properties in 14 vertical profiles of f the mid-Atlantic coast of the United States in June show excellent a greement. Simultaneous measurements of the chemical compositions of th e aerosol allows an assessment of the chemical apportionment of the ae rosol column optical depths. The optical depths had essentially three chemical components, which, in order of descending average contributio ns, were condensed water, carbonaceous species, and sulfate. These res ults do not support the common assumption that sulfate dominates aeros ol optical depths in polluted regions.