Combined radar observations of equatorial electrojet irregularities at Jicamarca

Hysell, D. L.; Drexler, Judith Z.; Shume, E. B.; Chau, Jorge L.; Scipion, Danny; Vlasov, M. N.; Cuevas, R. A.; Heinselman, C. J.

doi:10.5194/angeo-25-457-2007

Cited by 32 publications

(49 citation statements)

References 63 publications

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“…This eddy turbulence results in a local maximum of the temperature in the upper mesosphere/lower thermosphere and could correspond either to an unusually high mesopause or to a double mesosphere. Although complicated by plasma dynamic effects and ongoing controversy, our interpretation of Farley-Buneman wave phase velocity (Hysell et al, 2007) is consistent with a low Brunt-Väisälä frequency in the region of interest. Nitric oxide transport due to eddy diffusion from the lower thermosphere to the mesosphere causes electron density changes in the E region whereas NO density modulation due to irregularities in the eddy diffusion coefficient creates variability in the electron density.…”

supporting

confidence: 51%

“…Significant electron density striations, neutral temperatures 27 K above nominal, and intense wind shear were observed in the E-region ionosphere over the Jicamarca Radio Observatory during an unusual event on 26 July 2005 (Hysell et al, 2007). In this paper, these results are used to estimate eddy turbulence parameters and their effects.…”

mentioning

confidence: 99%

“…In the past few years new experimental approaches to studying the daytime equatorial electrojet have been developed that overcome many of the limitations imposed by plasma processes (see companion paper Hysell et al, 2007). These limitations include Faraday rotation measurements using the plasma waves as scatterers on an oblique path (Hysell and Chau, 2002;Shume et al, 2005b); an improved ability to image plasma structures in the unstable region with interferometric methods (Hysell and Chau, 2006); an inversion technique to deduce neutral winds from the Doppler shift of oblique plasma waves (Shume et al, 2005a); identification of the Doppler shift of "150 km echoes" with E×B drifts due to the zonal electric field (Kudeki and Fawcett, 1993); and establishment of a new AMISR prototype radar at 430 MHz at Jicamarca (Cuevas et al, 2007 1 ).…”

Section: Introductionmentioning

confidence: 99%

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Eddy turbulence parameters inferred from radar observations at Jicamarca

2007

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Abstract. Significant electron density striations, neutral temperatures 27 K above nominal, and intense wind shear were observed in the E-region ionosphere over the Jicamarca Radio Observatory during an unusual event on 26 July 2005 (Hysell et al., 2007). In this paper, these results are used to estimate eddy turbulence parameters and their effects. Models for the thermal balance in the mesosphere/lower thermosphere and the charged particle density in the E region are developed here. The thermal balance model includes eddy conduction and viscous dissipation of turbulent energy as well as cooling by infrared radiation. The production and recombination of ions and electrons in the E region, together with the production and transport of nitric oxide, are included in the plasma density model. Good agreement between the model results and the experimental data is obtained for an eddy diffusion coefficient of about 1×10 3 m 2 /s at its peak, which occurs at an altitude of 107 km. This eddy turbulence results in a local maximum of the temperature in the upper mesosphere/lower thermosphere and could correspond either to an unusually high mesopause or to a double mesosphere. Although complicated by plasma dynamic effects and ongoing controversy, our interpretation of Farley-Buneman wave phase velocity (Hysell et al., 2007) is consistent with a low Brunt-Väisälä frequency in the region of interest. Nitric oxide transport due to eddy diffusion from the lower thermosphere to the mesosphere causes electron density changes in the E region whereas NO density modulation due to irregularities in the eddy diffusion coefficient creates variability in the electron density.

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confidence: 51%

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confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Eddy turbulence parameters inferred from radar observations at Jicamarca

2007

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“…11 for example) daytime type 1 echoes with both positive and negative Doppler shifts at the same time and the same altitude! This apparent paradox is explained by interferometry and imaging data (e.g., Farley et al, 1981;Hysell et al, 2007, and several earlier references therein) that show that the upand down-traveling waves come from different portions of the (fairly small, usually) scattering volume, when the length of the dominant large-scale waves is smaller than the zonal dimension of the scattering volume (as it is during the day, but not at night). In other words, roughly horizontal electric fields associated with the large-scale (kilometers) waves are as strong as or perhaps even somewhat stronger than the mean vertical electric fields, and so there will be large "local" background drift velocities more or less parallel to the radar k-vector for a wide range of zenith angles (including zero).…”

Section: Common Assumptions For the Equatorial Geometrymentioning

confidence: 99%

“…This tutorial is meant to be an introduction to the instabilities rather than a complete review of five decades of work. A very thorough discussion of most of the current state of the art has recently been given by Hysell et al (2007).…”

Section: T Farley: Equatorial E-region Irregularitiesmentioning

confidence: 99%

The equatorial E-region and its plasma instabilities: a tutorial

Farley

2009

Ann. Geophys.

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Abstract. In this short tutorial we first briefly review the basic physics of the E-region of the equatorial ionosphere, with emphasis on the strong electrojet current system that drives plasma instabilities and generates strong plasma waves that are easily detected by radars and rocket probes. We then discuss the instabilities themselves, both the theory and some examples of the observational data. These instabilities have now been studied for about half a century (!), beginning with the IGY, particularly at the Jicamarca Radio Observatory in Peru. The linear fluid theory of the important processes is now well understood, but there are still questions about some kinetic effects, not to mention the considerable amount of work to be done before we have a full quantitative understanding of the limiting nonlinear processes that determine the details of what we actually observe. As our observational techniques, especially the radar techniques, improve, we find some answers, but also more and more questions. One difficulty with studying natural phenomena, such as these instabilities, is that we cannot perform active cause-and-effect experiments; we are limited to the inputs and responses that nature provides. The one hope here is the steadily growing capability of numerical plasma simulations. If we can accurately simulate the relevant plasma physics, we can control the inputs and measure the responses in great detail. Unfortunately, the problem is inherently three-dimensional, and we still need somewhat more computer power than is currently available, although we have come a long way.

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Multiscale equatorial electrojet turbulence:Baseline 2‐D model

et al. 2015

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The spatial and spectral characteristics of the turbulent plasma density, electric fields, and ion drift in ionospheric E region are studied using a new set of nonlinear plasma fluid equations. The fluid model combines both Farley-Buneman (Type-I) and Gradient-Drift (Type-II) plasma instabilities in the equatorial electrojet. In our unified model of the plasma instabilities, we include the ion viscosity in the ion momentum equation and electron inertia in the electron momentum equation. These two terms play an important role in stabilizing the growing modes in the linear regime and in driving the Farley-Buneman instability into the saturation state. The simulation results show good agreements with a number of features of rocket and radar observations, such as (1) saturation of plasma density perturbations depends on the solar condition and reaches 7-15% relative to the background, (2) fluctuation of the horizontal secondary electric field reaches 8-15 mV/m, (3) stabilization of the phase velocity of the perturbed density wave around the value of the ion-acoustic speed inside the electrojet, (4) "up-down" asymmetry in the vertical fluxes of the plasma density, (5) "east-west" asymmetry of the plasma zonal drifts, and (6) generation of small scale of the order of meter scale lengths irregularities embedded in large-scale structures. Spectral analysis of the density fluctuations reveals the energy cascade due to the nonlinear coupling between structures of different scales. The break-up of the large-scale structures into small-scale structures explains the disappearance of Type-II echoes in the presence of Type-I instabilities.

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Combined radar observations of equatorial electrojet irregularities at Jicamarca

Cited by 32 publications

References 63 publications

Eddy turbulence parameters inferred from radar observations at Jicamarca

Eddy turbulence parameters inferred from radar observations at Jicamarca

The equatorial E-region and its plasma instabilities: a tutorial

Multiscale equatorial electrojet turbulence:Baseline 2‐D model

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