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Detailed Reference Information |
Hysell, D.L. and Kelley, M.C. (1997). Decaying equatorial F region plasma depletions. Journal of Geophysical Research 102: doi: 10.1029/97JA01725. issn: 0148-0227. |
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We analyze plasma density data from the AE-E satellite to determine how F region irregularities decay. This satellite had a low inclination orbit that was ultimately circular at an altitude of 434 km. It frequently observed plasma depletions in the postsunset regime during spread F conditions, sometimes along a trajectory affording a horizontal cut perspective through the field-aligned irregularities. On one occasion, the satellite passed through nearly the same region of depleted flux tubes on sequential orbits. Data from these orbits imply that the irregularities decay at a constant rate over a broad range of horizontal scale sizes. We introduce a statistical model of the intermediate-scale (10 km--100 m) plasma irregularities and use it to infer a value for the perpendicular ambipolar diffusion coefficient from the measured decay rate. The value we estimate (2 m2/s) is close to the expected classical value. The uniform decay rate and the quasi-universal nature of the intermediate-scale spectra hint that the irregularities themselves maintain a characteristic shape as they decay. High-resolution satellite density measurements show that irregularities have the form of kilometer-scale quasi-periodic depletions. We propose a one-dimensional, nonlinear model of the collisional interchange instability which admits a closed-form, steady state solution predicting the shape of the depletions. Computer simulations of the model produce kilometer-scale waves that resemble the in situ observations.¿ 1997 American Geophysical Union |
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Abstract |
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Keywords
Ionosphere, Equatorial ionosphere, Ionosphere, Ionospheric irregularities, Ionosphere, Modeling and forecasting, Ionosphere, Plasma temperature and density |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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