Reconfiguration of polar-cap plasma in the magnetic midnight sector

Pryse, S. E.; Wood, Alan; Middleton, H. R.; McCrea, I. W.; Lester, M.

doi:10.5194/angeo-24-2201-2006

Cited by 13 publications

(11 citation statements)

References 29 publications

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“… Pryse et al [2004] found that photoionization and convection were also the source of polar cap plasma found near local magnetic noon but separate from the main body of photoionization. In a later study in the dusk‐midnight sector, Pryse et al [2006b] used tomography and SuperDARN convection patterns to numerically track a polar patch from the anti‐sunward convection flow, through the Harang discontinuity and into sunward flow, where it formed a boundary blob.…”

Section: Discussionmentioning

confidence: 99%

The role of the tongue‐of‐ionization in the formation of the poleward wall of the main trough in the European post‐midnight sector

2008

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[1] A series of radio tomography reconstructions from the University of Wales Aberystwyth receiver chains in Scandinavia and the UK, imaging the midnight-dawn sector on 13 December 2001, reveal a persistent large-scale electron density enhancement, which forms the poleward wall of the main ionization trough. Measurements by the European Incoherent Scatter radar (EISCAT) rule out in situ soft-particle precipitation as the main source of the higher densities. SuperDARN plasma drift observations and electric potential patterns place the feature in the dawn cell of the high-latitude convection, leading to the conclusion that the higher density is likely to have originated as photoionization and was convected over the polar cap to the nightside and around toward dawn in a tongue-of-ionization (TOI). Suitable runs of the Coupled ThermosphereIonosphere-Plasmasphere (CTIP) model support this interpretation and also reveal that the formation of the TOI is heavily UT dependent, which would lead to it being most prominent at nighttime in the European sector.Citation: Middleton, H. R., S. E. Pryse, A. G. Wood, and R. Balthazor (2008), The role of the tongue-of-ionization in the formation of the poleward wall of the main trough in the European post-midnight sector,

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Section: Discussionmentioning

confidence: 99%

The role of the tongue‐of‐ionization in the formation of the poleward wall of the main trough in the European post‐midnight sector

2008

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“…Patches convecting into the auroral oval have been shown to be associated with substorm onset [Lyons et al, 2011;Nishimura et al, 2013Nishimura et al, , 2014Shi and Zesta, 2014]. In the auroral oval, they are termed auroral blobs [Tsunoda, 1988;Crowley et al, 2000;Lorentzen et al, 2004;Pryse et al, 2006]. Several types of auroral blobs are referred to in literature, namely, boundary blobs, subauroral blobs, and auroral blobs [e.g., Crowley et al, 2000].…”

Section: Polar Cap Patch Activitymentioning

confidence: 99%

Severe and localized GNSS scintillation at the poleward edge of the nightside auroral oval during intense substorm aurora

et al. 2015

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In this paper we study how GPS, GLONASS, and Galileo navigation signals are compromised by strong irregularities causing severe phase scintillation (σϕ>1) in the nightside high‐latitude ionosphere during a substorm on 3 November 2013. Substorm onset and a later intensification coincided with polar cap patches entering the auroral oval to become auroral blobs. Using Global Navigation Satellite Systems (GNSS) receivers and optical data, we show severe scintillation driven by intense auroral emissions in the line of sight between the receiver and the satellites. During substorm expansion, the area of scintillation followed the intense poleward edge of the auroral oval. The intense auroral emissions were colocated with polar cap patches (blobs). The patches did not contain strong irregularities, neither before entering the auroral oval nor after the aurora had faded. Signals from all three GNSS constellations were similarly affected by the irregularities. Furthermore, two receivers spaced around 120km apart reported highly different scintillation impacts, with strong scintillation on half of the satellites in one receiver and no scintillation in the other. This shows that areas of severe irregularities in the nightside ionosphere can be highly localized. Amplitude scintillations were low throughout the entire interval.

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“…The modeled and observed values at the final location were compared and agreed within experimental uncertainties. PLASLIFE had also been used previously to assist in the interpretation of observations in the nightside ionosphere [ Pryse et al , 2006; Wood et al , 2008].…”

Section: Instrumentation and Simulationmentioning

confidence: 99%

“… Robinson et al [1985] modeled a patch drifting out of the polar cap, which was reconfigured to form a boundary blob in the nightside auroral oval. Subsequent observations have shown patches drifting out of the polar cap [ Pedersen et al , 2000] and being reconfigured to form a boundary blob [ Pryse et al , 2006].…”

Section: Introductionmentioning

confidence: 99%

Seasonal influence on polar cap patches in the high‐latitude nightside ionosphere

Wood

Pryse

2010

J. Geophys. Res.

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[1] The influence of the season on the patch-to-background density ratio of polar cap patches in the nightside ionosphere was observed above northern Scandinavia around solar maximum (1999)(2000)(2001). This is the first study of the seasonal effect in the nightside polar ionosphere. The observations were conducted by the European Incoherent Scatter Svalbard Radar under conditions favorable for patches based on the high-latitude plasma convection pattern, the interplanetary magnetic field, and an absence of in situ precipitation. Patch-to-background ratios of up to 9.4 ± 2.9 were observed between midwinter and equinox, with values of up to 1.9 ± 0.2 in summer. As the patch-to-background ratios in summer were <2, the enhancements could not formally be called patches; however, these were significant density enhancements within the antisunward cross-polar flow. Aberystwyth University's PLASLIFE (PLASma LIFEtime) computer simulation was used to model the observed seasonal trend in the patch-to-background ratio and to establish reasons for the difference between winter and summer values. This difference was primarily attributed to variation in the chemical composition of the atmosphere, which, in summer, both reduced the electron densities of the plasma drawn into the polar cap on the dayside and enhanced plasma loss by recombination. A secondary factor was the maintenance of the background polar ionosphere by photoionization in summer.

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Reconfiguration of polar-cap plasma in the magnetic midnight sector

Cited by 13 publications

References 29 publications

The role of the tongue‐of‐ionization in the formation of the poleward wall of the main trough in the European post‐midnight sector

The role of the tongue‐of‐ionization in the formation of the poleward wall of the main trough in the European post‐midnight sector

Severe and localized GNSS scintillation at the poleward edge of the nightside auroral oval during intense substorm aurora

Seasonal influence on polar cap patches in the high‐latitude nightside ionosphere

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