Radar Backscatter from Underdense Meteors and Diffusion Rates |
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| Authors: | Werner Singer Ralph Latteck Luis Federico Millan Nick J Mitchell Jens Fiedler |
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| Institution: | (1) Leibniz Institute of Atmospheric Physics, Schlossstr. 6, 18225 Kuhlungsborn, Germany;(2) Chalmers University of Technology, Gothenborg, Sweden;(3) University of Bath, Bath, UK |
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| Abstract: | Many meteoroids burn up between about 120 km and 70 km, deposit metals and dust and form ionized trails which are detected
by radars. Model studies about the influence of neutral or positively charged background dust on the ambipolar diffusion indicate
that significant smaller decay times should be observed for weak meteor echoes compared to strong meteor echoes which can
affect the estimation of temperatures. The variation of meteor decay times in dependence on echo strength, height, and season
was studied using radar observations at 69° N, 22° S, and 67° S. Significantly reduced decay times were found for weak echoes
below about 88 km at low latitudes throughout the year, and at high latitudes with the exception of summer. In summer at high
latitudes, decreasing decay times of weak and strong meteors are observed at altitudes below about 85 km during the appearance
of noctilucent clouds. The impact of reduced decay times on the estimation of neutral temperatures from decay times is discussed. |
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| Keywords: | Diffusion Mesopause Meteor Meteor radar Temperature |
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