Accession Number : ADA270273

Title :   An Investigation of Warm-Cloud Microphysics Using a Multi-Component Cloud Model: Interactive Effects of the Aerosol Spectrum.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : Zahn, Stephen G.

Report Date : DEC 1993

Pagination or Media Count : 118

Abstract : Clouds, especially low, warm, boundary-layer clouds, play an important role in regulating the earth's climate due to their significant contribution to the global albedo. The radiative effects of individual clouds are controlled largely by cloud microstructure, which is itself sensitive to the concentration and spectral distribution of the atmospheric aerosol. Increases in aerosol particle concentrations from anthropogenic activity could result in increased cloud albedo and global cloudiness, increasing the amount of reflected solar radiation. However, the effects of increased aerosol particle concentrations could be offset by the presence of giant or ultragiant aerosol particles. A one-dimensional, multi-component microphysical cloud model has been used to demonstrate the effects of aerosol particle spectral variations on the microstructure of warm clouds. Simulations performed with this model demonstrate that the introduction of increased concentrations of giant aerosol particles has a destabilizing effect on the cloud microstructure. Also, it is shown that warm-cloud microphysical processes modify the aerosol particle spectrum, favoring the generation of the largest sized particles via the collision-coalescence process. These simulations provide further evidence that the effect of aerosol particles on cloud microstructure must be addressed when considering global climate forecasts.

Descriptors :   *AEROSOLS, *ATMOSPHERICS, *BOUNDARY LAYER, *CLIMATE, *CLOUDS, *SOLAR RADIATION, *METEOROLOGY, ALBEDO, COALESCENCE, COLLISIONS, DISTRIBUTION, GLOBAL, LAYERS, MICROSTRUCTURE, MODELS, ONE DIMENSIONAL, PARTICLES, SIMULATION, VARIATIONS, PHYSICS, SPECTRA, THESES, ASTROPHYSICS, PHYSICS, SPECTRA.

Subject Categories : Meteorology
      Fluid Mechanics
      Astrophysics

Distribution Statement : APPROVED FOR PUBLIC RELEASE