First measurements of radar coherent scatter by the Radio Aurora Explorer CubeSat

Bahcivan, H.; Cutler, James; Bennett, Matthew W.; Kempke, Benjamin; Springmann, John C.; Buonocore, J.; Nicolls, M. J.; Doe, R. A.

doi:10.1029/2012gl052249

Cited by 9 publications

(11 citation statements)

References 17 publications

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“…These threshold observations parallel those made in the comparisons of in situ sounding rocket electric field and ground‐based imaging radar data during the two Joule campaigns in Alaska [ Bahcivan et al , ; Hysell et al , ]. Although not discussed here, in a previous paper [ Bahcivan et al , ], we reported that the phase velocity obeys the empirical formula C s cos θ . To our knowledge, the profiles shown in Figure provide the first altitudinally resolved estimates of magnetic aspect sensitivity of submeter‐scale auroral irregularities. The backscatter is confined to the altitude range of 106–112 km (3 dB points), as seen on Figure (left).…”

Section: Discussionsupporting

confidence: 87%

Section: Discussionsupporting

confidence: 87%

“…Note that we assume the ionosphere was horizontally homogeneous and that the echoes originating inside the radar beam were driven by the same electric field. As we reported in Bahcivan et al [], the electric field as measured using six PFISR beams was fairly uniform throughout the PFISR imaging area.…”

Section: Observationssupporting

confidence: 78%

“…The wave is driven by an E × B drift of 1543 m/s in a plasma with the following parameters representing the E × B drift and plasma conditions during EXPT1017: C s =562 m/s, flow s −1 , ν e =25000 s −1 , and B =0.5 G. The C s value is empirically set based on the formula of Nielsen and Schlegel []. As reported in Bahcivan et al [], that empirical value and the C s cos θ expression matched the measured phase speed (300–400 m/s) within the uncertainty of a wind‐driven ion drift. Figure shows that the growth rate maximizes around ±0.75°.…”

Section: Discussionmentioning

confidence: 94%

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Magnetic aspect sensitivity of high‐latitude E region irregularities measured by the RAX‐2 CubeSat

et al. 2014

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The second Radio Aurora Explorer (RAX‐2) satellite has completed more than 30 conjunction experiments with the Advanced Modular Incoherent Scatter Radar chain of incoherent scatter radars in Alaska and Resolute Bay, Canada. Coherent radar echoing occurred during four of the passes: three when E region electron drifts exceeded the ion acoustic speed threshold and one during HF heating of the ionosphere by the High Frequency Active Auroral Research Program heater. In this paper, we present the results for the first three passes associated with backscatter from natural irregularities. We analyze, in detail, the largest drift case because the plasma turbulence was the most intense and because the corresponding ground‐to‐space bistatic scattering geometry was the most favorable for magnetic aspect sensitivity analysis. A set of data analysis procedures including interference removal, autocorrelation analysis, and the application of a radar beam deconvolution algorithm mapped the distribution of E region backscatter with 3 km resolution in altitude and ∼0.1° in magnetic aspect angle. To our knowledge, these are the highest resolution altitude‐resolved magnetic aspect sensitivity measurements made at UHF frequencies in the auroral region. In this paper, we show that despite the large electron drift speed of ∼1500 m/s, the magnetic aspect sensitivity of submeter scale irregularities is much higher than previously reported. The root‐mean‐square of the aspect angle distribution varied monotonically between 0.5° and 0.1° for the altitude range 100–110 km. Findings from this single but compelling event suggest that submeter scale waves propagating at larger angles from the main E×B flow direction (secondary waves) have parallel electric fields that are too small to contribute to E region electron heating. It is possible that anomalous electron heating in the auroral electrojet can be explained by (a) the dynamics of those submeter scale waves propagating in the E×B direction (primary waves) or (b) the dynamics of longer wavelengths.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionsupporting

confidence: 87%

Section: Observationssupporting

confidence: 78%

Section: Discussionmentioning

confidence: 94%

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Magnetic aspect sensitivity of high‐latitude E region irregularities measured by the RAX‐2 CubeSat

et al. 2014

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“…On 8 March 2012, RAX-2 recorded the first FAI-related echo [33]. The experiment was conducted with PFISR, and the resulting rangetime-intensity plot is shown in Fig.…”

Section: Rax-2 Was Launched On 28mentioning

confidence: 99%

Radio Aurora Explorer: A Mission Overview

Cutler

Bahcivan

2014

Journal of Spacecraft and Rockets

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The primary objective of the Radio Aurora Explorer mission is to study plasma instabilities that lead to magnetic field aligned irregularities of electron density in the lower polar ionosphere (80-400 km). These irregularities are known to disrupt communication and navigation signals. The Radio Aurora Explorer mission uses a bistatic radar configuration; the spacecraft is the radar receiver and the transmitters are several worldwide incoherent scatter radars of which the primary radar is located in Poker Flat, Alaska. The satellites are 3 kg, university-class CubeSats with a primary payload of a direct-conversion radar receiver operating in the frequency range from 426 to 510 MHz. The satellite bus has a novel configuration of processing, attitude control, and antenna design that met the physical constraints of the CubeSat form factor and the one-year schedule constraint imposed by launch dates. Two satellites have launched: RAX

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Kinetic simulations of 3‐D Farley‐Buneman turbulence and anomalous electron heating

Oppenheim

Dimant

2013

JGR Space Physics

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[1] Electric fields map from the magnetosphere to the E region ionosphere where they drive the intense currents of the auroral electrojet. Particularly during geomagnetic storms and substorms, these currents become sufficiently intense to develop Farley-Buneman (FB) streaming instabilities and become turbulent. This leads to anomalous electron heating which can raise the electron temperature from 300 K to as much as 4000 K and, also, modifies auroral conductivities. This paper describes the first fully kinetic 3-D simulations of electric field-driven turbulence in the electrojet and compares the results with 2-D simulations and observations. These simulations show that 3-D turbulence can dramatically elevate electron temperatures, enough to explain the observed heating. They also show the saturated amplitude of the waves; coupling between linearly growing modes and damped modes; the propagation of the dominant modes at phase velocities near the acoustic velocity, slower than in 2-D simulations; and anomalous cross-field electron transport, leading to a greatly increased E region Pedersen conductivity. These simulations provide information useful in accurately modeling FB turbulence and represent significant progress in understanding the electrojet.

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First measurements of radar coherent scatter by the Radio Aurora Explorer CubeSat

Cited by 9 publications

References 17 publications

Magnetic aspect sensitivity of high‐latitude E region irregularities measured by the RAX‐2 CubeSat

Magnetic aspect sensitivity of high‐latitude E region irregularities measured by the RAX‐2 CubeSat

Radio Aurora Explorer: A Mission Overview

Kinetic simulations of 3‐D Farley‐Buneman turbulence and anomalous electron heating

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