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Brightness variations in satellite images of cloud-free. ocean regions have been hypothesized to be caused by marine aerosol particle variations. The objective of this dissertation is to quantitatively examine the relationship between marine aerosol particles and satellite-detected radiance. Further. the causes of particle variations which lead to upwelling radiance variation. particularly relative humidity effects. are investigated.Both theoretical and experimental approaches are taken to attain these objectives. First. a two-stream radiative transfer model is used to calculate upwelling radiance variations caused by calculated aerosol particle variations. Variations of particle scattering characteristics due to composition. total number (due to wind speed variation). and size (due to relative humidity variation) are investigated.Second. an experiment designed to relate near-simultaneous satellite images to marine boundary layer characteristics was conducted off shore of southern California from 20 September to 7 October. 1982.Satellite images were analyzed in real-time and used to direct an aircraft to regions of brightness variations detected in the images.The aircraft measured atmospheric state variables and aerosol particle characteristics in the regions of interest. This set of measurements is used to compare satellite-detected radiance with known aerosol particle characteristics and atmospheric state variables.From the theoretical and experimental results it is concluded that satellite-detected radiance is positively correlated with aerosol optical depth. Also. marine boundary layer radiative extinction is related to relative humidity. Therefore. since satellite-detected radiance is related to total extinction (optical depth) and extinction i.s related to relative humidity, satellite-detected radiance is related to relative humidity.The relationship between boundary layer relative humidity and satellite-detected radiance is limited by significant numbers of particles above the boundary layer. Upper le~el particles are shown to result fram a mixture of marine, terrestrial and possibly urban sources.])me to composition and size distribution differences, the wavelength dependence of the particle scattering characteristics is greater for situations influenced by upper level particles than those where only marine particles are present. Following this reasoning, the ratio of satellite-detected radiance at red and near infrared wavelengths is shown to detect the presence of significant amounts of upper level particles. ACKNOWLEDGEMENTS

The relationships between the physical and chemical properties of mixed-phase clouds were investigated at Storm Peak Laboratory (3220m MSL) located near the continental divide in northwestern Colorado. Interstitial aerosol particles, cloud droplets and snow crystals were concurrently collected when the laboratory was enveloped by a precipitating cloud. All samples were analyzed for trace elements, soluble anions, electrical conductivity and acidity.The results show average trace constituent concentration ratios of cloud water to snow water range from 0.4 to 26. All but six of the 32 elements and ions measured had ratios greater than one. This result suggests a chemical species dependency of in-cloud aerosol particle scavenging processes. Evidence of a decrease of in-cloud aerosol particle scavenging efficiency by snow due to increases in aerosol concentration is also presented.Differences between the chemical composition of cloud water and snow water are manifested most strongly when snow crystals grow by vapor deposition. In-cloud scavenging efficiencies by snow crystals for most aerosol particle chemical species are dependent on the growth of the snow crystals by accretion of cloud droplets. This chemical fractionation of the atmospheric aerosol by snow crystal formation and growth should be most active where narrow, continental cloud droplet size distributions and low liquid water contents are prevalent, enhancing the probability of snow crystal growth by diffusion.

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