scholarly journals Simulation of off-great circle HF propagation effects due to the presence of patches and arcs of enhanced electron density within the polar cap ionosphere

Radio Science ◽  
2003 ◽  
Vol 38 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
N. Y. Zaalov ◽  
E. M. Warrington ◽  
A. J. Stocker
Keyword(s):  
Electron Density ◽  
Great Circle ◽  
Polar Cap ◽  
Hf Propagation ◽  
Propagation Effects

scholarly journals Polar patches observed by ESR and their possible origin in the cusp region

2000 ◽  
Vol 18 (9) ◽  
pp. 1043-1053 ◽  
Author(s):  
A. M. Smith ◽  
S. E. Pryse ◽  
L. Kersley
Keyword(s):  
Energy Distribution ◽  
Electron Density ◽  
Plasma Flow ◽  
Plasma Temperature ◽  
Soft Particle ◽  
Polar Ionosphere ◽  
Polar Cap ◽  
Particle Precipitation ◽  
Cusp Region ◽  
Reconnection Site

Abstract. Observations by the EISCAT Svalbard radar in summer have revealed electron density enhancements in the magnetic noon sector under conditions of IMF Bz southward. The features were identified as possible candidates for polar-cap patches drifting anti-Sunward with the plasma flow. Supporting measurements by the EISCAT mainland radar, the CUTLASS radar and DMSP satellites, in a multi-instrument study, suggested that the origin of the structures lay upstream at lower latitudes, with the modulation in density being attributed to variability in soft-particle precipitation in the cusp region. It is proposed that the variations in precipitation may be linked to changes in the location of the reconnection site at the magnetopause, which in turn results in changes in the energy distribution of the precipitating particles.Key words: Ionosphere (ionosphere-magnetosphere interactions; plasma temperature and density; polar ionosphere)

Break up of a polar cap patch in the nightside ionosphere due to a flow channel event

2020 ◽  
Author(s):  
Elizabeth Donegan-Lawley ◽  
Alan Wood ◽  
Gareth Dorrian ◽  
Alexandra Fogg ◽  
Timothy Yeoman ◽  
...  
Keyword(s):  
Electron Density ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Flow Channel ◽  
Navigation Satellite ◽  
Polar Cap ◽  
Incoherent Scatter ◽  
Radar Network ◽  
Incoherent Scatter Radars ◽  
Global Navigation Satellite

<p>Flow channel events have previously been observed breaking up polar cap patches on the dayside ionosphere but, to the best of our knowledge, have not been observed on the nightside. We report observations of a flow channel event in the evening of the 9th January 2019 under quiet geomagnetic conditions. This multi-instrument study was undertaken using a combination of multiple EISCAT (European Incoherent Scatter) radars, SuperDARN (Super Dual Auroral Radar Network), MSP (Meridian Scanning Photometer) and GNSS (Global Navigation Satellite System) scintillation data. These data were used to build a picture of the evening’s observations from 1800 to 2359 UT. The flow channel event lasted a total of 13 minutes and was responsible for segmenting a polar cap patch. A decrease in electron density was observed, from a patch value of 1.4x10<sup>11</sup> m<sup>3</sup> to a minimum value of 5x10<sup>10</sup> m<sup>3</sup>. In addition, ion velocities in excess of 1000 ms<sup>-1</sup> and ion temperatures of greater than 2000 K were also observed. </p>

Measurements of the extent to which round-the-world HF propagation follows a great circle

1964 ◽  
Vol 52 (4) ◽  
pp. 418-419 ◽  
Author(s):  
R.B. Fenwick ◽  
O.G. Villard ◽  
E.C. Hayden ◽  
R. Bredek
Keyword(s):  
Great Circle ◽  
Hf Propagation ◽  
The World
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