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Lidar observations of Ca and K metallic layers from Arecibo and comparison with micrometeor sporadic activity by S. Raizada; C.A. Tepley; D. Janches; J.S. Friedman; Q. Zhou; J.D. Mathews is a Physics and Astronomy article available to read on EtoBox.

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We report on the ÿrst simultaneous observations of Ca and K metallic layers using the low-latitude lidar systems located at the Arecibo Observatory in Puerto Rico (18:35 • N, 66:75 • W). We often observe sudden increases in both Ca and K densities during early morning hours on nights where meteor showers take place. During these periods, the Ca/K abundance ratio varied between 2 and 3. On occasion, di erences were observed in Ca and K layers, which relate to di erences in the chemistry of the two metals. It is known that metallic layers display distinct seasonal variations, but chemistry alone cannot explain the measured di erences. Thus, we examined whether or not the seasonal distribution of micrometeoroids, derived from meteor observations using the Arecibo 430 MHz radar, can account for the dissimilar metallic observations. We found that the deposition ux of micrometeoroids, with particle sizes ranging between 0.5 and 100 m, increased by a factor of two during the summer as compared with the winter, suggesting a seasonal variation of their sporadic activity. In addition, our data support the idea that di erential ablation leads to a depletion of Ca atoms in the mesosphere.

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Author

S. Raizada; C.A. Tepley; D. Janches; J.S. Friedman; Q. Zhou; J.D. Mathews

Publisher

Elsevier Science; Elsevier ; Elsevier Ltd.; Elsevier BV (ISSN 1364-6826)

Published

2004

Language

EN

Field

Physics and Astronomy (Physical Sciences)