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Science 16 April 2004:
Vol. 304. no. 5669, pp. 426 - 428
DOI: 10.1126/science.1093236
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Reports

Removal of Meteoric Iron on Polar Mesospheric Clouds

John M. C. Plane,1* Benjamin J. Murray,1 Xinzhao Chu,2 Chester S. Gardner2

Polar mesospheric clouds are thin layers of nanometer-sized ice particles that occur at altitudes between 82 and 87 kilometers in the high-latitude summer mesosphere. These clouds overlap in altitude with the layer of iron (Fe) atoms that is produced by the ablation of meteoroids entering the atmosphere. Simultaneous observations of the Fe layer and the clouds, made by lidar during midsummer at the South Pole, demonstrate that essentially complete removal of Fe atoms can occur inside the clouds. Laboratory experiments and atmospheric modeling show that this phenomenon is explained by the efficient uptake of Fe on the ice particle surface.

1 School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
2 Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

* To whom correspondence should be addressed. E-mail: j.plane{at}uea.ac.uk

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