Smoke and Dust Particles of Meteoric Origin in the Mesosphere and Stratosphere

Donald M. Hunten Department of Planetary Sciences, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721

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Richard P. Turco R & D Associates, Marina del Rey, CA 90291

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Owen B. Toon Space Science Division, NASA Ames Research Center, Moffett Field, CA 94087

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Abstract

A height profile of ablated mass from meteors is calculated, assuming an incoming mass of 10−16 g cm−2 s−1 (44 metric tons per day) and the velocity distribution of Southworth and Sekanina, which has a mean of 14.5 km s−1. The profile peaks at 84 km. The fluxes of micrometeorites and residual meteoroids are also calculated. The coagulation of the evaporated silicates into “smoke” particles is then followed by means of a model adapted from a previous study of the stratospheric sulfate layer. Numerous sensitivity tests are made. Features of the results are a sharp cutoff of the particle distribution above 90 km, and a surface area close to 10−9 cm2 cm−3 all the way from 30 to 85 km. Some confirmation is obtained from balloon studies of condensation nuclei, although the various measurements differ greatly. The optical scattering and extinction am shown to be undetectable. Several potential applications are suggested: nucleation of sulfate particles and noctilucent clouds, scavenging of metallic ions and atoms, and perhaps other aeronomical effects. The latter are limited to processes that can be influenced by a collision time of the order of a day.

Abstract

A height profile of ablated mass from meteors is calculated, assuming an incoming mass of 10−16 g cm−2 s−1 (44 metric tons per day) and the velocity distribution of Southworth and Sekanina, which has a mean of 14.5 km s−1. The profile peaks at 84 km. The fluxes of micrometeorites and residual meteoroids are also calculated. The coagulation of the evaporated silicates into “smoke” particles is then followed by means of a model adapted from a previous study of the stratospheric sulfate layer. Numerous sensitivity tests are made. Features of the results are a sharp cutoff of the particle distribution above 90 km, and a surface area close to 10−9 cm2 cm−3 all the way from 30 to 85 km. Some confirmation is obtained from balloon studies of condensation nuclei, although the various measurements differ greatly. The optical scattering and extinction am shown to be undetectable. Several potential applications are suggested: nucleation of sulfate particles and noctilucent clouds, scavenging of metallic ions and atoms, and perhaps other aeronomical effects. The latter are limited to processes that can be influenced by a collision time of the order of a day.

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