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Metal Layers |
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About 50 tonnes of interplanetary dust enters the earth's atmosphere every day, at velocities ranging from 11 to 72 km
s-1. Most of this dust appears to vaporize completely, producing the layers of metal atoms such as Na and Fe that occur
globally in the upper mesosphere and lower thermosphere (between 80 and 105 km). Several metal atoms - Na, K, Fe and Ca - can be
observed by ground-based lidar (laser radar), and this has provided a great deal of information about the physics and chemistry of an
important region that forms the boundary between the atmosphere and space. Our main contribution to this field has been to study the elementary reactions that these metals undergo in the upper atmosphere. The resulting reaction rate coefficients and photochemical cross sections are then used to construct models. The laboratory techniques that we use are: laser flash photolysis with detection of metallic species by laser induced fluorescence; and the fast flow tube with detection of neutral species by LIF, and ions by mass spectrometry. For a review of these techniques, see Plane, Chemical Reviews, 2003. Below are tables of recommended rate coefficients from our laboratory studies. Recommended rate coefficients for metal layer modelling (pdf file: 88.9 KB) |
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Modelling the Fe layer at South Pole during summer |
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For information related to this project Go to > Mesosphere > Meteor Smoke |
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