Perturbations of the upper atmosphere in the cleft region |
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| Authors: | Gerd W Prlss |
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| Institution: | aArgelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany |
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| Abstract: | In the dayside polar region—loosely referred to as the cleft region—particle precipitation and Joule heating cause significant perturbations of the upper atmosphere. Here Dynamics Explorer-2 satellite data are used to present a synopsis of these disturbance effects. Documented are an increase in electron temperature and a decrease in electron density; increases in ion drift speed and ion temperature; an increase in the upward-directed ion velocity; increases in zonal wind speed and neutral gas temperature; and changes in the neutral gas composition and mass density. It is suggested that the increase in electron temperature is partly controlled by the decrease in electron density; that the ion upflow velocity mainly depends on the electron temperature, less frequently on the ion temperature; and that the observed decrease in thermospheric mass density is due to a decrease in the atomic oxygen density, which in turn is caused by diverging wind flows. |
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| Keywords: | Polar upper atmosphere Cleft/cusp region Ionospheric perturbation Thermospheric perturbation |
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