Journal ArticleDOI
Gravity wave initiation of equatorial spread F: A case study
TLDR
In this article, the authors show that although initiation by a gravity wave seems likely, the gravity wave interaction cannot yield the large displacements observed without further amplification by the Rayleigh-Taylor instability.Abstract:
Jicamarca radar backscatter maps were made during four consecutive nights in March 1979. Two of these maps displayed single towering plumes extending to nearly 1000-km altitude. On a third night, discussed in detail here, six plumes were generated in clear association with a nearly sinusoidal oscillation of the height of the bottomside of the F layer. The vertical amplitude of the oscillation was several hundred kilometers, and the period about 100 minutes. The plumes were generated either when the bottomside of the F layer was at the highest altitude or in the descending phase of the motion. Families of curves are presented which correspond to the solution of the dispersion relation for gravity waves capable of initiating the observed bottomside oscillations via the spatial resonance mechanism. We conclude that the solutions thus derived are reasonable and present a criterion for how well matched the gravity wave phase velocity and plasma drift have to be to produce a given perturbation in the ionization density. This criterion indicates that although initiation by a gravity wave seems likely, the gravity wave interaction cannot yield the large displacements observed without further amplification by the Rayleigh-Taylor instability. Finally, we show that the preferential generation of plumes during the descending phase of the F layer height oscillation can be explained by a generalized Rayleigh-Taylor instability operating on the distorted ionosphere with the destabilizing effects of gravity, a zonal electric field, and a zonal neutral wind included.read more
Citations
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Journal ArticleDOI
Control of the seasonal and longitudinal occurrence of equatorial scintillations by the longitudinal gradient in integrated E region Pedersen conductivity
TL;DR: In this article, the seasonal maxima in scintillation activity coincide with the times of year when the solar terminator is most nearly aligned with the geomagnetic flux tubes, and the occurrence of plasma density irregularities responsible for scintillations is most likely when the integrated E-region Pedersen conductivity is changing most rapidly.
Journal ArticleDOI
Nonlinear equatorial spread F: The effect of neutral winds and background Pedersen conductivity
TL;DR: In this paper, a simple model of the interaction of the equatorial ionosphere with the eastward F region neutral wind in the presence of evolving spread F bubbles is given, where the upper portions of bubbles will take on a westward tilt, while the lower portions will tilt eastward, giving rise to the 'fishtails' and 'C's' observed by coherent backscatter radar measurements of fieldaligned small-scale irregularities.
Journal ArticleDOI
Initial observations with the Global Ultraviolet Imager (GUVI) in the NASA TIMED satellite mission
Andrew B. Christensen,Larry J. Paxton,Susan K. Avery,John D. Craven,G. Crowley,David C. Humm,Hyosub Kil,R. R. Meier,C.-I. Meng,Daniel Morrison,B. Ogorzalek,Paul R. Straus,D. J. Strickland,R. M. Swenson,Richard L. Walterscheid,Brian C. Wolven,Yongliang Zhang +16 more
TL;DR: The Global Ultraviolet Imager (GUVI) was used by the NASA TIMED satellite to measure the spectral radiance of the Earth's far ultraviolet airglow in the spectral region from 120 to 180 nm using a cross-track scanning spectrometer design as discussed by the authors.
Journal ArticleDOI
Outstanding problems in the equatorial ionosphere–thermosphere electrodynamics relevant to spread F
TL;DR: In this article, the authors discuss the key factors that control the ESF generation by generalized Rayleigh-Taylor instability process, such as the prereversal enhancement electric field (vertical drift) that is controlled by post-sunset zonal wind and longitudinal conductivity gradients, meridional/transequatorial winds, flux tube integrated conducitvities, and seed perturbations.
Journal ArticleDOI
C/NOFS: a Mission to Forecast Scintillations
TL;DR: The communication/navigation outage forecasting system (C/NOFS) mission of the Air Force Research Laboratory as discussed by the authors is the first satellite solely dedicated to forecasting ionospheric irregularities and radio wave scintillations.
References
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Journal ArticleDOI
Radar observations of F region equatorial irregularities
Ronald F. Woodman,Cesar La Hoz +1 more
TL;DR: In this paper, the results of backscatter observations of the F region irregularities made with the large 50MHz radar at Jicamarca, Peru, during a few days of observations are presented.
Journal ArticleDOI
Polarization fields produced by winds in the equatorial F-region
TL;DR: In this article, the E-layer conductivity may be too small to close this circuit, so that polarization fields build up in the F-layer, causing the plasma to drift with the wind.
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Global propagation of atmospheric gravity waves: A review
TL;DR: The theoretical and observational evidence concerning the global propagation of atmospheric gravity waves is reviewed in this article, with special emphasis on the waves generated in the auroral zones, and it is concluded that the only natural sources of large-scale TIDs are in the ionospheric zones.
Journal ArticleDOI
Plasma bubbles and irregularities in the equatorial ionosphere
TL;DR: This paper observed large-scale (10 to 200-km) irregular biteouts of up to three orders of magnitude in the ion concentration in the nighttime equatorial F region associated with small-scale inhomogeneities in ion concentration.
Journal ArticleDOI
Acoustic‐gravity waves in the upper atmosphere
Kung C. Yeh,Chao H. Liu +1 more
TL;DR: In this article, the authors review the theory of acoustic-gravity waves, the interaction of such waves with the ionosphere, the experimental support for the existence of acoustic gravity waves in the upper atmosphere, and the role played by acoustic gravity wave in thermospheric dynamics.