Nonlinear evolution of equatorial spread F. 2. Gravity wave seeding of Rayleigh-Taylor instability
- Cornell Univ., Ithaca, NY (United States)
The authors have performed numerical simulations of nonlinear evolution of the Rayleigh-Taylor instability in equatorial spread F (ESF) under different conditions. Their main purpose is to explain the generation of multiple plumes on the west wall of a plasma upwelling and the relationship between gravity waves and large scale ESF irregularities. They have studied ESF structures resulting from one-dimensional or two-dimensional initial density perturbations an initiated by gravity waves. It is found that although plasma bubbles may be produced in all the situations, the production of the plasma bubbles initiated by gravity waves takes a time much shorter than that resulting from two-dimensional initial density perturbations. This is in agreement with a simple analytic nonlinear theory. The authors put their emphasis on the ESF structures growing from two different scale perturbations. The Rayleigh-Taylor instability initiated by gravity waves produces a steep gradient on the well wall, which provides a favorable condition for excitation of smaller-scale secondary instabilities. When both a seed gravity wave and a smaller-scale initial density perturbation are used, it is observed that the large-scale gravity wave determines the outer scale of results in multiple plumes preferentially located on the west wall. The production, rise, and bifurcation of plasma bubbles are reproduced in the simulations. 31 refs., 6 figs.
- OSTI ID:
- 254447
- Journal Information:
- Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: A1 Vol. 101; ISSN JGREA2; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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