Heating of Thermal Ions Near the Equatorward Boundary of the Mid-Altitude Polar Cleft

1989 ◽  
pp. 103-113 ◽  
Author(s):  
W. K. Peterson ◽  
M. André ◽  
A. M. Persoon ◽  
C. J. Pollock ◽  
G. B. Crew ◽  
...  
Keyword(s):  
Equatorward Boundary

scholarly journals Correspondence between the ULF wave power spatial distribution and auroral oval boundaries

2016 ◽  
Vol 2 (2) ◽  
pp. 46-65 ◽  
Author(s):  
Ольга Козырева ◽  
Olga Kozyreva ◽  
Вячеслав Пилипенко ◽  
Vyacheslav Pilipenko ◽  
Марк Энгебретсон ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spectral Power ◽  
Recovery Phase ◽  
Temporal Variations ◽  
Auroral Oval ◽  
Wave Power ◽  
Observational Result ◽  
Equatorward Boundary ◽  
Image Satellite ◽  
Magnetospheric Field

The world-wide spatial distribution of the wave power in the Pc5 band during magnetic storms has been compared with auroral oval boundaries. The poleward and equatorward auroral oval boundaries are estimated using either the British Antarctic Survey database containing IMAGE satellite UV observations of the aurora or the OVATION model based on the DMSP particle data. The “epicenter” of the spectral power of broadband Pc5 fluctuations during the storm growth phase is mapped inside the auroral oval. During the storm recovery phase, the spectral power of narrowband Pc5 waves, both in the dawn and dusk sectors, is mapped inside the auroral oval or around its equatorward boundary. This observational result confirms previously reported effects: the spatial/temporal variations of the Pc5 wave power in the morning/pre-noon sector are closely related to the dynamics of the auroral electrojet and magnetospheric field-aligned currents. At the same time, narrowband Pc5 waves demonstrate typical resonant features in the amplitude-phase latitudinal structure. Thus, the location of the auroral oval or its equatorward boundary is the preferred latitude for magnetospheric field-line Alfven resonator excitation. This effect is not taken into account by modern theories of ULF Pc5 waves, but it could be significant for the development of more adequate models.

scholarly journals Dayside cosmic noise absorption at the equatorward boundary of auroral oval as observed from Maitri, Antarctica ( L  = 5; CGM 62.45°S, 55.45°E)

2016 ◽  
Vol 121 (4) ◽  
pp. 3198-3211 ◽  
Author(s):  
Jayanta K. Behera ◽  
Ashwini K. Sinha ◽  
Geeta Vichare ◽  
Olga Kozyreva ◽  
Rahul Rawat ◽  
...  
Keyword(s):  
Auroral Oval ◽  
Noise Absorption ◽  
Equatorward Boundary ◽  
Cosmic Noise

Satellite observations of spatial and temporal fluctuations in post-midnight auroras

1981 ◽  
Vol 59 (8) ◽  
pp. 1137-1142 ◽  
Author(s):  
C. D. Anger ◽  
J. S. Murphree ◽  
L. L. Cogger
Keyword(s):  
Local Time ◽  
Plasma Sheet ◽  
Large Scale ◽  
Early Morning ◽  
Temporal Variations ◽  
Satellite Observations ◽  
Two Dimensional ◽  
Temporal Fluctuations ◽  
Equatorward Boundary ◽  
Diffuse Aurora

ISIS 2 satellite observations of the equatorward boundary of the diffuse aurora in the early morning magnetic local time (MLT) sector reveal irregularities in that boundary which are identified as a pulsating aurora. In the case of "cartwheel" data, repeated scans made through the same meridian reveal clear temporal variations in regions having scale sizes on the order of 300–400 km in north–south extent and intensities up to 60% of the diffuse auroral intensity poleward of the pulsations. When the pulsations are observed there are no corresponding fluctuations in intensity at the poleward boundary.When two-dimensional scans of the morning section are carried out, similar irregularities can be seen which range from quasi-periodic (in MLT) patch-like regions at the equatorward boundary, to north–south elongated irregularities in the diffuse aurora as a whole. Abrupt longitudinal boundaries in the irregularity regions can be seen particularly toward later MLT, suggesting that purely statistical analyses of latitude and local time distributions may not do justice to the phenomena involved.It seems quite likely that these irregularities indicate regions of pulsating auroras, in which case the pulsation regions are associated with remarkably orderly large scale fluctuations in the plasma sheet and thus may need to be viewed as something more than an irregular phenomenon governed entirely by local instabilities.

scholarly journals SuperDARN E-region backscatter boundary in the dusk-midnight sector – tracer of equatorward boundary of the auroral oval

2002 ◽  
Vol 20 (12) ◽  
pp. 1899-1904 ◽  
Author(s):  
P. T. Jayachandran ◽  
E. F. Donovan ◽  
J. W. MacDougall ◽  
D. R. Moorcroft ◽  
J.-P. St. Maurice ◽  
...  
Keyword(s):  
Energy Flux ◽  
Proton Energy ◽  
Auroral Oval ◽  
Ionospheric Irregularities ◽  
Auroral Ionosphere ◽  
Particle Precipitation ◽  
Equatorward Boundary ◽  
E Region ◽  
Proton Aurora

Abstract. We compare the locations of the equatorward boundaries of SuperDARN E-region backscatter and Hb  emissions, focusing on the dusk-midnight sector of the auroral oval where the proton aurora is statistically located equatorward of the discrete electron aurora. We show that, whenever both boundaries can be simultaneously identified, they are coincident. Our result complements earlier studies, which demonstrated the correspondence between the DMSP b2i boundary and both the equatorward boundary of the proton auroral oval (Donovan et al., 2002), and the equatorward boundary of SuperDARN E-region echoes (Jayachandran et al., 2002). Further, our result shows that, provided there is sufficient precipitating proton energy flux, the SuperDARN radars can be used to monitor the equatorward edge of the proton auroral oval.Key words. Ionosphere (auroral ionosphere; particle precipitation; ionospheric irregularities)

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