Academic Journal
New insights from a nonlocal generalization of the Farley-Buneman instability problem at high latitudes
| العنوان: | New insights from a nonlocal generalization of the Farley-Buneman instability problem at high latitudes |
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| المؤلفون: | J. Drexler, J.-P. St.-Maurice, D. Chen, D. R. Moorcroft |
| المصدر: | Annales Geophysicae, Vol 20, Pp 2003-2025 (2002) |
| بيانات النشر: | Copernicus Publications, 2002. |
| سنة النشر: | 2002 |
| المجموعة: | LCC:Science LCC:Physics LCC:Geophysics. Cosmic physics |
| مصطلحات موضوعية: | Science, Physics, QC1-999, Geophysics. Cosmic physics, QC801-809 |
| الوصف: | When their growth rate becomes too small, the E-region Farley-Buneman and gradient-drift instabilities switch from absolute to convective. The neutral density gradient is what gives the instabilities their convective character. At high latitudes, the orientation of the neutral density gradient is close to the geomagnetic field direction. We show that this causes the wave-vector component along the geomagnetic field to increase with time. This in turn leads to wave stabilization, since the increase goes hand-in-hand with an increase in parallel electric fields that ultimately short-circuits the irregularities. We show that from an equivalent point of view, the increase in the parallel wave vector is accompanied by a large upward group velocity that limits the time during which the perturbations are allowed to grow before escaping the unstable region. The goal of the present work is to develop a systematic formalism to account for the propagation and the growth/decay of high-latitude Farley-Buneman and gradient-drift waves through vertical convective effects. We note that our new formalism shies away from a plane wave decomposition along the magnetic field direction. A study of the solution to the resulting nonlinear aspect angle equation shows that, for a host of initial conditions, jump conditions are often triggered in the parallel wave-vector (defined here as the vertical derivative of the phase). When these jump conditions occur, the waves turn into strongly damped ion-acoustic modes, and their evolution is quickly terminated. We have limited this first study to Farley-Buneman modes and to a flow direction parallel to the electron E × B drift. Our initial findings indicate that, irrespective of whether or not a jump in aspect angle is triggered by initial conditions, the largest amplitude modes are usually near the ion-acoustic speed of the medium (although Doppler shifted by the ion motion), unless the growth rates are small, in which case the waves tend to move at the same drift as the ambient electrons.Key words. Ionosphere (auroral ionosphere; ionospheric irregularities; plasma waves and instabilities) |
| نوع الوثيقة: | article |
| وصف الملف: | electronic resource |
| اللغة: | English |
| تدمد: | 0992-7689 1432-0576 |
| Relation: | https://www.ann-geophys.net/20/2003/2002/angeo-20-2003-2002.pdf; https://doaj.org/toc/0992-7689; https://doaj.org/toc/1432-0576 |
| DOI: | 10.5194/angeo-20-2003-2002 |
| URL الوصول: | https://doaj.org/article/53284fa59543431a8bbb2c99a344a357 |
| رقم الانضمام: | edsdoj.53284fa59543431a8bbb2c99a344a357 |
| قاعدة البيانات: | Directory of Open Access Journals |
Full Text Finder | تدمد: | 09927689 14320576 |
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| DOI: | 10.5194/angeo-20-2003-2002 |