Measurements of Some Aerosol Properties Relevant to Radiative Forcing on the East Coast of the United States

Airborne measurements of aerosol light-scattering efficiencies are presented for a portion of the northeast Atlantic seaboard of the United States during July 1993. The measurements suggest a value for the sulfate lightscattering efficiency in the range 2.2–3.2 m2 g−1, which is lower than the value used in recent modeling assessments of the climate impact of aerosols. In general, the sulfate light-scattering efficiency decreased with increasing altitude in a manner consistent with concurrent measurements of aerosol size distributions. Some limited measurements of cloud condensation nuclei and sea-salt particles are also presented.