Physics
Scientific paper
Feb 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005jgra..11002303b&link_type=abstract
Journal of Geophysical Research, Volume 110, Issue A2, CiteID A02303
Physics
5
Ionosphere: Equatorial Ionosphere, Ionosphere: Ionospheric Irregularities, Ionosphere: Plasma Waves And Instabilities (2772), Ionosphere: Ionospheric Dynamics
Scientific paper
The unstable Rayleigh-Taylor plasma modes that are believed to be responsible for the density irregularities in the nighttime F region equatorial ionosphere have been studied before by assuming that the modes are electrostatic. In this paper, these plasma modes are studied without such assumption in order to determine the strength and the characteristics of the magnetic field fluctuations and to determine the physical condition under which the electrostatic assumption is justified. It is found that the relevant magnetic field fluctuations ($\widetilde{Bρ), which arise from the fluctuating parallel (to B0) current density, are associated with the shear Alfven waves. The parameter that determines the amplitude of $\widetilde{Bρ is α(s) ≡ Dm(s)k$\varphi$2/γ, where Dmk$\varphi$2 represents the rate at which magnetic field fluctuations with perpendicular wavelength λ$\varphi$(≡ 2π/k$\varphi$) diffuse away due to parallel resistivity and γ is the rate at which the fluctuations grow. Typically, α $\gg$ 1 in the equatorial ionosphere, which means that the excited magnetic field fluctuations diffuse at a rate much faster than their growth rate and, consequently, their amplitudes remain very small (compared to B0). Thus the Rayleigh-Taylor modes in the equatorial ionosphere are predominantly electrostatic in nature, and the electrostatic assumption of the previous analyses is quite justified. If the maximum amplitude of the electric field fluctuations ($\widetilde{E$\varphi$) is taken to be 1 mV/m, then the maximum amplitude of $\widetilde{Bρ is found to be less than 0.2 nT when λ$\varphi$ is 500 m, and it increases to about 2.4 nT when λ$\varphi$ is 20 km. Longer wavelength modes have somewhat larger magnetic field fluctuations, but their growth rates are smaller. While the maximum amplitude of $\widetilde{E$\varphi$ occurs at the magnetic equator, that of $\widetilde{Bρ occurs at a distance away from it.
No associations
LandOfFree
Characteristics of electromagnetic Rayleigh-Taylor modes in nighttime equatorial plasma does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Characteristics of electromagnetic Rayleigh-Taylor modes in nighttime equatorial plasma, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Characteristics of electromagnetic Rayleigh-Taylor modes in nighttime equatorial plasma will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1361459