Polar cap plasma patch primary linear instability growth rates compared

Burston, Robert; Mitchell, Cathryn N.; Astin, Ivan

doi:10.1002/2015ja021895

Cited by 15 publications

(31 citation statements)

References 41 publications

(88 reference statements)

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“…The second is associated with the technique (equation ) adopted to estimate the full electric field strength necessitated by the failure of the z axis component of VEFI. The work of Burston et al [] estimate that the derived electric field values are generally correct to an order of magnitude. Hence, this dominates the intrinsic instrument error, given as 0.1 mV m −1 , which can be neglected.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, in order to progress, a method of approximating the full electric field had to be adopted. The method used is identical to that described in Burston et al [] and uses

E \approx \sqrt{\frac{3}{2} ((), E_{x}^{2} + E_{y}^{2})},

where E x and E y are the x and y components of the electric field in spacecraft coordinates. The above applies equally to the quasi‐DC and AC data and equation was used for both cases.…”

Section: Methodsmentioning

confidence: 99%

“…Using Dynamics Explorer 2 satellite observations [ Burston et al , ] investigated the range of possible values for the linear growth rates for each of these processes. In that study, we found that the inertial KKT instability gave rise to the largest growth rates followed by those for inertial gradient drift, collisional turbulence and collisional shortwave current convective instabilities.…”

Section: Introductionmentioning

confidence: 99%

“…A number of explanations for the mechanism of irregularity formation within polar cap plasma patches and large-scale plasma structures in the polar regions have been proposed, including the current convective instability (CCI), first suggested in relation to auroral structures [Ossakow and Chaturvedi, 1979] and in plasma patches by Kelley [2009], the primary Kelvin-Helmholtz Instability (KHI) (possibly in conjunction with other processes) [e.g., Carlson et al, 2007;Gondarenko and Guzdar, 2006a;Oksavik et al, 2012], the gradient drift instability (GDI) [e.g., Basu et al, 1990;Burston et al, 2009;Chaturvedi et al, 1994;Gondarenko, and Guzdar, 2006b;Kivanc and Heelis, 1997;Weber et al, 1984] and a related "turbulent" process [Kelley and Kintner, 1978], which we term Kelley-Kintner-Turbulence (KKT). The term "turbulence" comes from magnetospheric electric fields that are turbulent in that they show continual variation at short time scales, and these fluctuations are also mapped to the ionosphere, exposing plasma to rapidly varying E × B drifts that can cause gradient drift instabilities, generating turbulent mixing of the plasma, if there is an electron concentration gradient present [Burston et al, 2010] Using Dynamics Explorer 2 satellite observations [Burston et al, 2016] investigated the range of possible values for the linear growth rates for each of these processes. In that study, we found that the inertial KKT instability gave rise to the largest growth rates followed by those for inertial gradient drift, collisional turbulence and collisional shortwave current convective instabilities.…”

Section: Introductionmentioning

confidence: 99%

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A comparison of the relative effect of the Earth's quasi‐DC and AC electric field on gradient drift waves in large‐scale plasma structures in the polar regions

2016

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Radio signals traversing polar cap plasma patches and other large‐scale plasma structures in polar regions are prone to scintillation. This implies that irregularities in electron concentration often form within such structures. The current standard theory of the formation of such irregularities is that the primary gradient drift instability drives a cascade from larger to smaller wavelengths that manifest as variations in electron concentration. The electric field can be described as the sum of a quasi‐DC and an AC component. While the effect of the quasi‐DC component has been extensively investigated in theory and by modeling, the contribution of the AC component has been largely neglected. This paper investigates the relative contributions of both components, using data from the Dynamics Explorer 2 satellite. It concludes that the contribution of the AC electric field to irregularity growth cannot be neglected. This has consequences for our understanding of large‐scale plasma structures in polar regions (and any associated radio scintillation) as the AC electric field component varies in all directions. Hence, its effect is not limited to the trailing edge of such structures, as it is for the quasi‐DC component. This raises the need for new experimental and modeling investigations of these phenomena.

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Section: Resultsmentioning

confidence: 99%

“…Hence, in order to progress, a method of approximating the full electric field had to be adopted. The method used is identical to that described in Burston et al [] and uses

E \approx \sqrt{\frac{3}{2} ((), E_{x}^{2} + E_{y}^{2})},

where E x and E y are the x and y components of the electric field in spacecraft coordinates. The above applies equally to the quasi‐DC and AC data and equation was used for both cases.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A comparison of the relative effect of the Earth's quasi‐DC and AC electric field on gradient drift waves in large‐scale plasma structures in the polar regions

2016

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“…Scintillation can degrade the performance of the Global Navigation Satellite System (GNSS) by causing loss of satellite lock and may lead to positioning errors (Moen et al, ; Pi et al, ). Previous work has proposed that polar cap patches may lead to scintillation through one or more of the following instability mechanisms: gradient drift, current convective, and Kelvin‐Helmholtz instabilities, as well as small‐scale “turbulence" processes (Atul et al, ; Burston et al, ; Moen et al, ). Because of this, it is important to study the formation and propagation of polar cap patches.…”

Section: Introductionmentioning

confidence: 99%

SuperDARN Evidence for Convection‐Driven Lagrangian Coherent Structures in the Polar Ionosphere

et al. 2019

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Polar cap patches are large sporadic enhancements of plasma density on the scale of hundreds of kilometers, which can impact the performance of Global Navigation Satellite Systems. Lagrangian Coherent Structures (LCSs) are ridges that show areas of maximal separation in a time‐evolving flow. Previous work based on modeled ionospheric flow showed that LCSs exist in the ionosphere and are barriers governing patch formation. In this work, we identify the first data‐driven LCSs in the high‐latitude ionosphere using Super Dual Auroral Radar Network (SuperDARN) ion convection fields. The LCSs found using the Ionosphere‐Thermosphere Algorithm for LCSs are compared during geomagnetically quiet and active periods. The shape of the LCS is found to be dependent on the electric potential pattern. A consistent two‐cell pattern results in a W‐shaped LCS, but when the two‐cell pattern breaks down, the LCS loses this characteristic shape. The changes in the electric potential, and thus the LCS, are likely due to changes in the interplanetary magnetic field. A comparison between LCSs obtained from empirical models and data reveal that the data‐driven LCSs are poleward of and have a shorter longitudinal span than the model‐based LCSs. A comparison of the LCS location and the formation of a polar cap patch on 17 March 2015 showed that the center of the patch developed from plasma on the main LCS ridge, and this is confirmed with a separate polar cap patch event from 26 September 2011.

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Radar observations of density gradients, electric fields, and plasma irregularities near polar cap patches in the context of the gradient‐drift instability

Lamarche

Makarevich

2017

JGR Space Physics

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We present observations of plasma density gradients, electric fields, and small‐scale plasma irregularities near a polar cap patch made by the Super Dual Auroral Radar Network radar at Rankin Inlet (RKN) and the northern face of Resolute Bay Incoherent Scatter Radar (RISR‐N). RKN echo power and occurrence are analyzed in the context of gradient‐drift instability (GDI) theory, with a particular focus on the previously uninvestigated 2‐D dependencies on wave propagation, electric field, and gradient vectors, with the latter two quantities evaluated directly from RISR‐N measurements. It is shown that higher gradient and electric field components along the wave vector generally lead to the higher observed echo occurrence, which is consistent with the expected higher GDI growth rate, but the relationship with echo power is far less straightforward. The RKN echo power increases monotonically as the predicted linear growth rate approaches zero from negative values but does not continue this trend into positive growth rate values, in contrast with GDI predictions. The observed greater consistency of echo occurrence with GDI predictions suggests that GDI operating in the linear regime can control basic plasma structuring, but measured echo strength may be affected by other processes and factors, such as multistep or nonlinear processes or a shear‐driven instability.

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Polar cap plasma patch primary linear instability growth rates compared

Cited by 15 publications

References 41 publications

A comparison of the relative effect of the Earth's quasi‐DC and AC electric field on gradient drift waves in large‐scale plasma structures in the polar regions

A comparison of the relative effect of the Earth's quasi‐DC and AC electric field on gradient drift waves in large‐scale plasma structures in the polar regions

SuperDARN Evidence for Convection‐Driven Lagrangian Coherent Structures in the Polar Ionosphere

Radar observations of density gradients, electric fields, and plasma irregularities near polar cap patches in the context of the gradient‐drift instability

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