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Proceedings Paper

Simulation of vertical profiles of extinction and backscatter coefficients in very low stratus clouds and subcloud regions
Author(s): Neal Harold Kilmer; Henry Rachele
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Paper Abstract

Two different methods (models) are used for simulating vertical profiles of extinction and backscatter coefficients in very low stratus clouds and subcloud regions. The first method makes use of a microphysics model developed by the authors. This model simulates drop size distributions as functions of height above the ground while considering the limitation on drop growth rate by the rate of diffusion of water vapor. Mie theory is then used with the drop size distributions and complex indices of refraction of water and material from condensation nuclei to simulate vertical profiles of extinction and backscatter coefficients. Comparison is made of profiles calculated by assuming the drops to be pure water with profiles calculated by considering the drops to be a combination of water and dry material. The second method uses vertical profiles of relative humidity and temperature simulated by the first method. These profiles are used to modify the reference level drop size distribution to simulate changes with height assuming the drops are in equilibrium with their immediate environment. The restriction of diffusion rate is not used in the second method. Applying Mie theory to the resulting drop size distributions yields a second set of profiles of extinction and backscatter coefficients. Profiles of these coefficients simulated by the first method appear more realistic than those simulated by the second method. Relationship between backscatter and extinction coefficients simulated by the first method also is shown.

Paper Details

Date Published: 1 July 1991
PDF: 14 pages
Proc. SPIE 1487, Propagation Engineering: Fourth in a Series, (1 July 1991); doi: 10.1117/12.46556
Show Author Affiliations
Neal Harold Kilmer, New Mexico State Univ. (United States)
Henry Rachele, U.S. Army Atmospheric Sciences Lab. (United States)


Published in SPIE Proceedings Vol. 1487:
Propagation Engineering: Fourth in a Series
Luc R. Bissonnette; Walter B. Miller, Editor(s)

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