Studies of the relationship between submicron marine aerosol and initial marine stratus properties
Date
1993-12
Authors
Jensen-Leute, Tara L., author
Kreidenweis, Sonia M., author
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Journal ISSN
Volume Title
Abstract
A systematic study of the relationship between submicron aerosols and the marine stratus cloud properties has been undertaken. The first part of the study included participation in the Atlantic Stratocumulus Transition Experiment - Marine Aerosol and Gas Exchange (ASTEX/MAGE) cooperative research experiment Measurements of submicron marine aerosol were collected using the Differential Mobility Particle Sizing (DMSP) system for determining the typical chemical composition and aerosol size distribution of marine aerosol. The second part of the investigation involved cloud process simulation with the Colorado State University dynamic cloud chamber. Marine aerosol distribution measurements were taken over a 25 day period from June 1 to June 25, 1992. Analysis of the data showed that the distributions were generally bimodal in clean air masses with total number concentrations ranging from 100 to 900 particles cm-3, while distributions were generally monomodal in polluted air masses with total number concentrations ranging from 800 to 1400 particles cm-3. Using the '"typical" thermodynamic and aerosol characteristics observed during the field project, the Colorado State University dynamic cloud chamber was used to conduct a well controlled study of the effects of submicron aerosol on the formation of marine stratus type clouds. Selected size distributions of ammonium sulfate were injected into the chamber and exposed to adiabatic expansions that simulated typical marine updraft velocities. Observations from the experiments were compared to model predictions from a one dimensional cloud model as well as other published modeling results. The dynamic cloud chamber, as configured for this study, was shown to be suitable for use in making stratus cloud simulations at updraft velocities greater than 1.0 m s-1. Mean diameter, liquid water content and dispersion coefficient values appeared to be comparable to the model predictions. Nucleated aerosol fraction trends agreed with model results. Details of the design, implementation and data interpretation are presented.
Description
December 1993.
Also issued as Tara L. Jensen-Leute's thesis (M.S.) -- Colorado State University, 1993.
Also issued as Tara L. Jensen-Leute's thesis (M.S.) -- Colorado State University, 1993.
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Subject
Clouds -- Dynamics
Aerosols -- Environmental aspects