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Nonlinear theory and experimental observations of the local collisional Rayleigh‐Taylor instability in a descending equatorial spread F ionosphere

1981; American Geophysical Union; Volume: 86; Issue: A7 Linguagem: Inglês

10.1029/ja086ia07p05785

2156-2202

M. J. Keskinen, E. P. Szuszczewicz, S. L. Ossakow, J. C. Holmes,

High-pressure geophysics and materials

The nonlinear evolution of the local collisional Rayleigh‐Taylor instability in downward‐moving equatorial F layers has been studied in a coordinated theoretical and experimental program dealing with actual conditions of bottomside spread F . For ambient bottomside electron density gradient scale lengths L =8 and 25 km, we find large percentage depletions and inverse power law spatial power spectra over the intermediate wavelength range λ=25 m‐1 km. In addition we outline a nonlinear theory of the collisional Rayleigh‐Taylor instability applicable to an upward‐ or downward‐moving equatorial F region ionosphere. The agreement between the experimental and theoretical results of this study lends further support to the belief that the collisional Rayleigh‐Taylor instability is responsible for large‐scale size irregularities that occur under conditions of equatorial spread F .