On determining the noon polar cap boundary from SuperDARN HF radar backscatter characteristics
Michael Pinnock,Alan S. Rodger +1 more
Reads0
Chats0
TLDR
In this paper, the authors examined the boundary determined over 6 h of magnetic local time around the noon sector and its relationship to the convection pattern using four SuperDARN radars and found that it is consistent with approximately 1 keV ions injected from a subsolar reconnection site.Abstract:
Previous work has shown that ionospheric HF radar backscatter in the noon sector can be used to locate the footprint of the magnetospheric cusp particle precipitation. This has enabled the radar data to be used as a proxy for the location of the polar cap boundary, and hence measure the flow of plasma across it to derive the reconnection electric field in the ionosphere. This work used only single radar data sets with a field of view limited to ∼2 h of local time. In this case study using four of the SuperDARN radars, we examine the boundary determined over 6 h of magnetic local time around the noon sector and its relationship to the convection pattern. The variation with longitude of the latitude of the radar scatter with cusp characteristics shows a bay-like feature. It is shown that this feature is shaped by the variation with longitude of the poleward flow component of the ionospheric plasma and may be understood in terms of cusp ion time-of-flight effects. Using this interpretation, we derive the time-of-flight of the cusp ions and find that it is consistent with approximately 1 keV ions injected from a subsolar reconnection site. A method for deriving a more accurate estimate of the location of the open-closed field line boundary from HF radar data is described.read more
Citations
More filters
Journal ArticleDOI
Variations in the polar cap area during two substorm cycles
Steve Milan,Mark Lester,Stanley W. H. Cowley,Kjellmar Oksavik,Mitchell J. Brittnacher,R. A. Greenwald,George J. Sofko,Jean-Paul Villain +7 more
TL;DR: In this article, the authors employed observations from several sources to determine the location of the polar cap bound-ary, or open/closed field line boundary, at all local times, allowing the amount of open flux in the magnetosphere to be quantified.
Journal ArticleDOI
Magnetic flux transport in the Dungey cycle: A survey of dayside and nightside reconnection rates
TL;DR: In this paper, changes in the open flux content of the ionospheric polar cap, estimated from auroral, radar, and low-Earth orbit particle measurements, are used to determine dayside and nightside reconnection rates during 73 hours of observation spread over nine intervals.
Journal ArticleDOI
On the collocation of the cusp aurora and the GPS phase scintillation: A statistical study
TL;DR: In this paper, the authors investigated the role of the cusp auroral processes in the production of irregularities, and found that the occurrence rate of the GPS phase scintillation is highest inside the auroral cusp, regardless of the scintillillation strength and the interplanetary magnetic field (IMF).
Journal ArticleDOI
Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1
TL;DR: In this paper, the first statistical study on auroral oval boundaries derived from small and medium-scale field-aligned currents (FACs) was presented, and the results were used for the first time.
Journal ArticleDOI
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements
Gareth Chisham,Mervyn P. Freeman +1 more
TL;DR: In this paper, a series of threshold algorithms were applied to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms and showed that simple threshold algorithms correctly identified the boundary location in, at most, 50% of the cases and that the average boundary error is at least ~ 1−2 range gates (~ 1° latitude).
References
More filters
Journal ArticleDOI
High spatial and temporal resolution observations of the ionospheric cusp
TL;DR: In this article, the Halley PACE HF radar has been operated in a new mode to provide very high time (10 s) and space (15 km) resolution measurements of the iono-spheric signatures of the cusp and the low-latitude boundary layer.
Journal ArticleDOI
Ion acceleration at the equatorward edge of the cusp: Low altitude observations of patchy merging
Patrick T. Newell,Ching-I. Meng +1 more
TL;DR: In this paper, the authors report the observation of spatially discrete patches of precipitating accelerated ions at the equatorward edge of the cusp, which occur at or near the transition between boundary layer and cusp proper, are spatially distinct from the overall energy-latitude dispersion in the main cusp and are best fitted by Maxwellian distributions with convection velocities of 450-640 km/s.
Journal ArticleDOI
Evidence of magnetospheric cusp proton acceleration by magnetic merging at the dayside magnetopause
T. W. Hill,P. H. Reiff +1 more
TL;DR: In this paper, the energy-latitude dispersion of protons observed in the low-altitude dayside cusp on two orbits of the AE-C satellite was analyzed in an attempt to reconstruct the velocity distribution of the source plasma.
Journal ArticleDOI
Simultaneous HF-radar and DMSP observations of the cusp
K. B. Baker,R. A. Greenwald,J. M. Ruohoniemi,J. R. Dudeney,Michael Pinnock,Patrick T. Newell,M. E. Greenspan,C.-I. Meng +7 more
TL;DR: In this article, the DMSP-F9 satellite passed through the Southern Hemisphere cusp while a coheret scatter HF-radar was observing 10-m scale irregularities present in the ionosphere.
Journal ArticleDOI
Meridian-scanning photometer, coherent HF radar, and magnetometer observations of the cusp: a case study
Stephen E. Milan,Mark Lester,Stanley W. H. Cowley,Joran Moen,Per Even Sandholt,Christopher J. Owen +5 more
TL;DR: In this paper, the CUTLASS Finland coherent HF radar, a meridian-scanning photometer located at Ny Alesund, Svalbard, and a meridional network of magnetometers, was used to study the dynamics of the cusp region and post- noon sector for an interval of predominantly IMF By, Bz < 0 nT.