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Science 2 March 2001:
Vol. 291. no. 5509, pp. 1772 - 1775
DOI: 10.1126/science.1057737
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Reports

Ablation, Flux, and Atmospheric Implications of Meteors Inferred from Stratospheric Aerosol

D. J. Cziczo,12 D. S. Thomson,12 D. M. Murphy1*

Single-particle analyses of stratospheric aerosol show that about half of the particles contain 0.5 to 1.0 weight percent meteoritic iron by mass, requiring a total extraterrestrial influx of 8 to 38 gigagrams per year. The sodium/iron ratio in these stratospheric particles is higher and the magnesium/iron and calcium/iron ratios are lower than in chondritic meteorites, implying that the fraction of material that is ablated must lie at the low end of previous estimates and that the extraterrestrial component that resides in the mesosphere and stratosphere is not of chondritic composition.

1 Aeronomy Laboratory, National Oceanic and Atmospheric Administration, Boulder, CO 80305, USA.
2 Cooperative Institute for Research in the Environmental Sciences, University of Colorado, Boulder, CO 80309, USA.
*   To whom correspondence should be addressed. E-mail: murphyd{at}al.noaa.gov

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Science. ISSN 0036-8075 (print), 1095-9203 (online)