Auroral pulsations and accompanying VLF emissions

Tagirov, V. R.; Ismagilov, V. S.; Титова, Е. Е.; Arinin, V. A.; Perlikov, A. M.; Manninen, J.; Turunen, T.; Kaila, K.

doi:10.1007/s005850050737

Cited by 19 publications

(22 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Deviations from other magnetic field models were investigated in our separate study [ Nishimura et al , 2011]. The existence of multiple cores and the expanding and propagating features of patches are similar to the events reported by Tagirov et al [1999].…”

Section: Correlation Between Pulsating Aurora and Lower‐band Chorussupporting

confidence: 61%

Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions

et al. 2011

View full text Add to dashboard Cite

[1] A multievent study was performed using conjugate measurements of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and an all-sky imager during periods of intense lower-band chorus waves. The thirteen identified cases support our previous finding, based on two events, that the intensity modulation of lower-band chorus near the magnetic equator is highly correlated with quasiperiodic pulsating auroral emissions near the spacecraft's magnetic footprint, indicating that lower-band chorus is the driver of the pulsating aurora. Furthermore, we identified a fortuitous measurement made simultaneously by two THEMIS spacecraft with small spatial separation. The two spacecraft were found to be located in a single pulsating chorus patch and the spacecraft footprints were in the same pulsating auroral patch when intense chorus bursts were measured simultaneously, whereas only one of the spacecraft's footprints was in a patch when the other spacecraft did not detect intense chorus. On the basis of this event, we can estimate the pulsating chorus patch size by mapping the pulsating auroral patches from the ionosphere toward the magnetic equator, giving a roughly circular region of ∼5000 km diameter for corresponding azimuthally elongated patches with ∼100 km size in the ionosphere. Using a ray-tracing-based calculation of the divergence of chorus raypaths from a point source, together with the corresponding resonant energies, we found that the chorus patch size is most probably not a result of ray divergence but a property of the wave excitation region.Citation: Nishimura, Y., et al. (2011), Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions,

show abstract

Section: Correlation Between Pulsating Aurora and Lower‐band Chorussupporting

confidence: 61%

Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions

et al. 2011

View full text Add to dashboard Cite

show abstract

“…The PsA is driven by a spikelike regime of a whistler cyclotron instability, whose free energy comes from the anisotropic velocity distribution of drifting energetic electrons, and the resulting impulsive precipitation of electrons in this plasma duct. This model was further improved by Tagirov et al [1999] to take into consideration the role of the ionosphere. Also owing to its ducted-propagating nature the whistler mode chorus can be detected on the ground, and were at time found correlated with the PsA activities [e.g., Hansen and Scourfield, 1990;Novikov et al, 1994;Tagirov et al, 1999].…”

Section: Introductionmentioning

confidence: 99%

“…This model was further improved by Tagirov et al [1999] to take into consideration the role of the ionosphere. Also owing to its ducted-propagating nature the whistler mode chorus can be detected on the ground, and were at time found correlated with the PsA activities [e.g., Hansen and Scourfield, 1990;Novikov et al, 1994;Tagirov et al, 1999]. On a perusal of the above reports of PsA-whistler wave correspondences we notice that their observations were all made at invariant latitudes L < 6.…”

Section: Introductionmentioning

confidence: 99%

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

et al. 2010

View full text Add to dashboard Cite

[1] We present multiprobe, multi-instrument observations of the electron cyclotron harmonic (ECH) emissions and ultralow-frequency (ULF) waves from Time History of Events and Macroscale Interactions during Substorms (THEMIS) and explore their potential linkage to the concurrent ground-observed pulsating auroras (PsA) on 4 January 2009. The ECH emissions were observed as discrete packets modulated by the ULF flapping motion of the neutral sheet around the probes. Combining different data sets of the ECH observations, we infer that the ECH emission intensities were strongly fluctuating and contained multi-time scale fine structures. The distribution of PsA patches featured longitudinal "wavelength" in concert with the in situ ULF wave characteristics inferred from a cross-phase analysis. The overall activeness of the PsA correlated with the in situ-measured energetic electron fluxes and ECH wave intensities. We suggest that ECH waves played the key role in the pitch angle diffusion of the plasma sheet electrons that led to the PsA, while the ULF waves structured the plasma sheet and imposed a macroscopic effect over the spatial distribution of the PsA.

show abstract

“…The patches were found to be associated with VLF emissions (e.g. Tagirov et al, 1999, and references herein). It has been concluded that the auroral patches are the result of pitch angle scattering of energetic electrons by magnetic whistler mode waves (Davidson, 1979;Tagirov et al, 1986).…”

Section: Discussionmentioning

confidence: 90%

Rocket-borne investigation of auroral patches in the evening sector during substorm recovery

Danielides

Kozlovsky

2003

Ann. Geophys.

View full text Add to dashboard Cite

Abstract. On 11 February 1997 at 08:36 UT after a substorm onset the Auroral Turbulence 2 sounding rocket was launched from Poker Flat Research Range, Alaska into a moderately active auroral region. This experiment has allowed us to investigate evening (21:00 MLT) auroral forms at the substorm recovery, which were discrete multiple auroral arcs stretched to, the east and southeast from the breakup region, and bright auroral patches propagating westward along the arcs like a luminosity wave, which is a typical feature of the disturbed arc. The rocket crossed an auroral arc of about 40 km width, stretched along southeast direction. Auroral patches and associated electric fields formed a 200 km long periodical structure, which propagated along the arc westward at a velocity of 3 km/s, whereas the ionospheric plasma velocity inside the arc was 300 m/s westward. The spatial periodicity in the rocket data was found from optical ground-based observations, from electric field in situ measurements, as well as from ground-based magnetic observations. The bright patches were co-located with equatorward plasma flow across the arc of the order of 200 m/s in magnitude, whereas the plasma flow tended to be poleward at the intervals between the patches, where the electric field reached the magnitude of up to 20 mV/m, and these maxima were co-located with the peaks in electron precipitations indicated by the electron counter on board the rocket. Pulsations of a 70-s period were observed on the ground in the eastern component of the magnetic field and this is consistent with the moving auroral patches and the north-south plasma flows associated with them. The enhanced patch-associated electric field and fast westward propagation suggest essential differences between evening auroral patches and those occurring in the morning ionosphere. We propose the wave that propagates along the plasma sheet boundary to be a promising mechanism for the evening auroral patches.

show abstract

Auroral pulsations and accompanying VLF emissions

Cited by 19 publications

References 0 publications

Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions

Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions

THEMIS observations of electron cyclotron harmonic emissions, ULF waves, and pulsating auroras

Rocket-borne investigation of auroral patches in the evening sector during substorm recovery

Contact Info

Product

Resources

About