EISCAT Svalbard radar observations of ionospheric signatures of magnetopause reconnection during a changing IMF Bz polarity

Pryse, S. E.; Smith, A. M.; Kersley, L.; McCrea, I. W.

doi:10.5194/angeo-20-477-2002

Cited by 2 publications

(2 citation statements)

References 17 publications

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“…Observations made by incoherent scatter radars in azimuth or elevation scanning modes have confirmed that these ionospheric structures extend both in latitude, longitude and altitude (e.g. Watermann et al, 1994;Valladares et al, 1999;Pryse et al, 2002), and at a given location the plasma density may change on time scales of a few minutes (Carlson et al, 2002). Therefore, it is not unlikely that there was a change in the F-region over northern Scandinavia just before 08:03 UT allowing the 1.5 F HF radio wave propagation mode to start.…”

Section: Counterstreaming Electrons In the Llbl/cuspmentioning

confidence: 98%

Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp

et al. 2004

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Abstract. In this paper we discuss counterstreaming electrons, electric field turbulence, HF radar spectral width enhancements, and field-aligned currents in the southward IMF cusp region. Electric field and particle observations from the FAST spacecraft are compared with CUTLASS Finland spectral width enhancements and ground-based optical data from Svalbard during a meridional crossing of the cusp. The observed 630 nm rayed arc (Type-1 cusp aurora) is associated with stepped cusp ion signatures. Simultaneous counterstreaming low-energy electrons on open magnetic field lines lead us to propose that such electrons may be an important source for rayed red arcs through pitch angle scattering in collisions with the upper atmosphere. The observed particle precipitation and electric field turbulence are found to be nearly collocated with the equatorward edge of the optical cusp, in a region where CUTLASS Finland also observed enhanced spectral width. The electric field turbulence is observed to extend far poleward of the optical cusp. The broad-band electric field turbulence corresponds to spatial scale lengths down to 5 m. Therefore, we suggest that electric field irregularities are directly responsible for the formation of HF radar backscatter targets and may also explain the observed wide spectra. FAST also encountered two narrow highly structured field-aligned current pairs flowing near the edges of cusp ion steps.

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Section: Counterstreaming Electrons In the Llbl/cuspmentioning

confidence: 98%

Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp

et al. 2004

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“…Enhanced convection under prolonged southward IMF creates a plume, and it is transported into the polar cap as a tongue of ionization (Foster et al., 2005). When the southward IMF is small, transport from the subauroral ionosphere is small, and density enhancements in the cusp become more important (Davies et al., 2002; Lorentzen et al., 2010; Oksavik et al., 2006; Pryse et al., 2002).…”

Section: Introductionmentioning

confidence: 99%

Cusp Dynamics and Polar Cap Patch Formation Associated With a Small IMF Southward Turning

et al. 2021

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The cusp is one of the most dynamic regions in the polar ionosphere. The cusp is located near noon just poleward of the open and closed magnetic field lines of the dayside magnetosphere-ionosphere system, and a variety of energy input processes from the magnetosheath and magnetopause characterize the cusp. Precipitation in the cusp is dominated by soft electrons and energetic protons, and impact ionization and precipitation heating primarily occur in the F-region ionosphere and thermosphere (Hardy et al., 1985;Skjaeveland et al., 2017). The cusp is located at the dayside convection throat, where fast flows transport plasma from closed to open field lines (Moen et al., 2001;Sandholt et al., 2003) and increases Joule heating (Shi et al., 2017). The heating in the cusp increases plasma upflows and thermospheric density (Carlson et al., 2012;Ogawa et al., 2009). In addition to the large-scale quasi-steady convection, pulsed flows propagate poleward in association with localized field-aligned currents. The footprint of the upward FACs is illuminated as discrete auroral arcs, and it is referred to as poleward moving auroral forms (PMAFs) (Oksavik et al., 2004). This transient system is characterized as a flow channel and a wedge-like current system.An important consequence of the cusp dynamics is formation of polar cap patches. During a large southward IMF, the open-closed boundary moves equatorward and photoionized plasma from the sunlit ionosphere becomes an important source of polar cap patches (

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EISCAT Svalbard radar observations of ionospheric signatures of magnetopause reconnection during a changing IMF Bz polarity

Cited by 2 publications

References 17 publications

Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp

Simultaneous optical, CUTLASS HF radar, and FAST spacecraft observations: signatures of boundary layer processes in the cusp

Cusp Dynamics and Polar Cap Patch Formation Associated With a Small IMF Southward Turning

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