Survey of Ionospheric Pc3‐5 ULF Wave Signatures in SuperDARN High Time Resolution Data

Shi, Xueling; Ruohoniemi, J. M.; Baker, J. B.; Lin, Dong; Bland, Emma; Hartinger, M.; Scales, W. A.

doi:10.1029/2017ja025033

Cited by 27 publications

(30 citation statements)

References 46 publications

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“…In this section, we describe the interplanetary and geomagnetic conditions during the wave event and analyze the wave properties in the magnetosphere and ionosphere to obtain the spatial extent and spectral features of long‐lasting poloidal ULF waves observed by multiple satellites and high‐latitude SuperDARN radars. This event was initially identified in the ULF event database from SuperDARN high‐time‐resolution data, which was built using an automated detection method based on the Lomb‐Scargle periodogram technique described by Shi et al ().…”

Section: Observationsmentioning

confidence: 99%

“…Range‐time‐intensity plots in Figure (left) show that these monochromatic ULF waves were mostly observed equatorward of lower frequency Pc5 waves at higher latitudes and lasted for a few hours as long as ionospheric backscatter persisted. Time series of LOS velocity in 0.5‐hr intervals incremented by 7.5 min from individual radar and range gate were analyzed separately for spectral power from 2016‐01‐24/20:00 UT to 2016‐01‐25/04:00 UT, using the Lomb‐Scargle periodogram technique reported in Shi et al (). Figure d shows the frequency of wave events from the three radars as a function of MLT.…”

Section: Observationsmentioning

confidence: 99%

“…Interestingly, the waves were usually monochromatic and observed during low geomagnetic activity after a geomagnetic storm or within the storm recovery phase, as summarized in Table . It is thought that a small convection electric field and plasmaspheric refilling during the recovery phase play key roles in the generation of the internal instabilities that drive these waves during these periods (Anderson et al, ; Dai et al, ; Liu et al, ; Sarris et al, ; Shi et al, ). Generally ground‐based magnetometers are unable to detect these high‐ m waves due to ionospheric screening effects (Hughes & Southwood, ); hence, simultaneous observations of these waves in the magnetosphere and conjugate ionosphere are rare, perhaps also in part owing to their localized radial extent and low occurrence rate (Anderson et al, ; Shi et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Long‐Lasting Poloidal ULF Waves Observed by Multiple Satellites and High‐Latitude SuperDARN Radars

et al. 2018

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Poloidal ultralow frequency (ULF) waves between 5 and 10 mHz were observed by multiple satellites and three high-latitude Super Dual Auroral Radar Network radars during the recovery phase of a moderate geomagnetic storm on 24-27 January 2016. The long-lasting ULF waves were observed in the magnetic field and energetic particle flux perturbations during three successive passes by two Geostationary Operational Environmental Satellites through the dayside magnetosphere, during which plasmasphere expansion and refilling were observed by two Time History of Events and Macroscale Interactions during Substorms probes. The radial magnetic field oscillation was in phase (∼180 ∘ out of phase) with the northward (southward) moving proton flux oscillation at 95 keV, consistent with high-energy drift-bounce resonance signatures of protons with second harmonic poloidal standing Alfvén waves. The longitudinal extent of the waves approached 10 hr in local time on the dayside and gradually decreased with time. High-time-resolution (∼6 s) data from three high-latitude Super Dual Auroral Radar Network radars show that the wave intensification region was localized in latitude with a radial extent of ∼135-225 km in the subauroral ionosphere. No signature of these waves were observed by ground-based magnetometers colocated with the Geostationary Operational Environmental Satellites suggesting that the poloidal waves were high-m mode and thus screened by the ionosphere. During this interval one of the Time History of Events and Macroscale Interactions during Substorms probes observed a bump-on-tail ion distribution at 1-3 keV, which we suggest is the source of the long-lasting second harmonic poloidal ULF waves.

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Section: Observationsmentioning

confidence: 99%

Section: Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Long‐Lasting Poloidal ULF Waves Observed by Multiple Satellites and High‐Latitude SuperDARN Radars

et al. 2018

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“…The SuperDARN network is an international chain of radars covering polar, high, and midlatitudes in the Northern and Southern Hemispheres (Chisham et al, 2007;Greenwald et al, 1985Greenwald et al, , 1995 and played an important role in advancing our knowledge of ionospheric electrodynamics (Kim et al, 2013;Prikryl et al, 2013;Ruohoniemi & Baker, 1998;Shi et al, 2018). The ionospheric plasma drift observed by the North American chain of midlatitude SuperDARN high-frequency radars (de Larquier et al, 2011;Kunduri et al, 2012;Maimaiti et al, 2018) is the primary data set used in the current study.…”

Section: Superdarn High-frequency Radarsmentioning

confidence: 99%

A New Empirical Model of the Subauroral Polarization Stream

et al. 2018

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Regions of persistent westward directed flows are often observed equatorward of the auroral oval in the dusk‐midnight sector. In general, the midnight narrow flows are termed as subauroral ion drifts and the duskside broader flows are termed subauroral polarization streams (SAPS). SAPS/subauroral ion drift electric fields play an important role in controlling the dynamics of the midlatitude ionosphere. In this paper we analyze longitudinally extended observations of SAPS measured by midlatitude Super Dual Auroral Radar Network (SuperDARN) radars under varied geomagnetic conditions. We find that SAPS speeds exhibit a strong dependence on geomagnetic activity, with flows exceeding 1,500 m/s during geomagnetic storms and dropping to 100 m/s during periods of geomagnetic quiet. Moreover, SAPS flows turn increasingly poleward when moving from the midnight sector toward dusk and this effect is more pronounced during disturbed geomagnetic conditions. The variations in SAPS speeds with magnetic local time (MLT) are also found to be strongly dependent on geomagnetic conditions. Specifically, SAPS speeds increase quasilinearly with MLT during disturbed geomagnetic conditions, whereas during relatively quiet geomagnetic conditions there is no discernible trend. This behavior suggests the possibility of different mechanisms influencing SAPS during geomagnetically quiet conditions. Average cross‐SAPS potentials increase with geomagnetic activity and typically vary between 15 and 45 kV. Finally, a new empirical model of SAPS potentials has been developed parameterized by Asy‐H index, MLT, and magnetic latitude.

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“…For many decades, ultra low frequency (ULF) waves in the Pc5 band (1–7 mHz) have been routinely observed by ground‐based magnetometer arrays (Baker et al, ; Mathie et al, ; Rae et al, ; Samson et al, ), SuperDARN radar (Fenrich et al, ; Shi et al, ), and in situ observations by satellites (Shi et al, , ; Takahashi et al, ) and have been considered a primary agency for the energization and transport of trapped particles within Earth's magnetosphere (Mann et al, ; O'Brien et al, , ; Rostoker et al, ). Two principal magneto‐hydrodynamic (MHD) wave types that are ubiquitous in the magnetosphere are MHD fast mode waves and Shear Alfvn waves (Allan & Poulter, ).…”

Section: Introductionmentioning

confidence: 99%

Alteration of Particle Drift Resonance Dynamics Near Poloidal Mode Field Line Resonance Structures

et al. 2019

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We examine the effect on drift‐resonant particle dynamics of a strongly peaked internally driven poloidal mode field line resonance (FLR; with specified frequency ω in the Pc5 range and azimuthal mode number m≫1). Using an analytic magneto‐hydrodynamic model in a dipole field to describe the ultra low frequency wave mode, we use the bounce‐averaged formalism of Northrop (1963) to obtain equations of motion for charged particles in the wave frame and find an analytic solution for the case of a temporally constant ultra low frequency wave amplitude profile. Focusing on equatorially mirroring electrons in this study, we demonstrate that, for sufficiently peaked radial profiles, multiple drift resonances appear that are associated with the FLR peak. These are in addition to the well‐known zeroth‐order drift resonance location, occurring when the unperturbed drift speed trueϕ̇0 satisfies the resonance condition ( mtrueϕ̇−ω=0). The additional resonances arise because the strongly peaked FLR wave field components provide sufficiently strong perturbations to the azimuthal drift speed to cause multiple zero crossings in the resonance condition. These additional resonances have trapping periods much lower than that of the zeroth‐order resonance and considerably complicate the electron dynamics. Further properties of these resonances and their measurable effect on electron dynamics are discussed. For example, their effect on observations of energetic electron flux on board satellites in the vicinity of an FLR is calculated and shown to significantly distort the typical signature associated with drift resonance (modulations in electron flux at the wave frequency with a 180° phase change across the resonant energy).

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Survey of Ionospheric Pc3‐5 ULF Wave Signatures in SuperDARN High Time Resolution Data

Cited by 27 publications

References 46 publications

Long‐Lasting Poloidal ULF Waves Observed by Multiple Satellites and High‐Latitude SuperDARN Radars

Long‐Lasting Poloidal ULF Waves Observed by Multiple Satellites and High‐Latitude SuperDARN Radars

A New Empirical Model of the Subauroral Polarization Stream

Alteration of Particle Drift Resonance Dynamics Near Poloidal Mode Field Line Resonance Structures

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