Chemical Heterogeneity across Cloud Droplet Size Spectra in Continental and Marine Air Masses

Variations in the Chemical Composition of cloud droplets of different sizes are predicted in models. Measurements made in natural clouds to verify this prediction are extremely limited. During The Spring of 1995 and the summers of 1995 and 1996, a size-fractionating version of the California Institute of Technology active-strand cloud water collector was operated on a mountain platform in Mount Mitchell State Park, North Carolina, to examine differences in drop chemistry between large and small cloud droplets.

Sulfate-induced cooling in the southeastern U.S.: An observational assessment.

The effect of sulfates on cloud microphysical and optical properties have been studied using data from a rural mountaintop location in the Mt.Mitchell State Park, North Carolina. Although the amended Clean Air Act has limited the sulfur emissions beginning 1990, we found the sulfate concentrations greater during 1993-97 compared to that during 1986-89. Cloud albedo inferred from satellite data and calculated from surface observations does not indicate monotonic increase with increasing sulfates. The direct and indirect sulfate forcing are assesses to be 4.8 and -4 W m^-2. These values exceed current model predictions as evaluated by other investigators. Surface temperature records of the region during 1949-94 indicate a cooling trend tacitly supporting our assessment.