scholarly journals A survey of 25 years' transpolar voltage data from the SuperDARN radar network and the Expanding-Contracting Polar Cap model

2021 ◽  
Author(s):  
Michael Lockwood ◽  
Kathryn A McWilliams
Keyword(s):  
2021 ◽  
Vol 2103 (1) ◽  
pp. 012034
Author(s):  
D P Barsukov ◽  
A A Matevosyan ◽  
I K Morozov ◽  
A N Popov ◽  
M V Vorontsov

Abstract The influence of surface small-scale magnetic field on the heating of PSR J0250+5854 polar cap is considered. It is assumed that the polar cap is heated only by reverse positrons accelerated in pulsar diode. It is supposed that pulsar diode is located near the star surface (polar cap model) and operates in the steady state space charge-limited flow regime. The reverse positron current is calculated in the framework of two models: rapid and gradually screening. To calculate the production rate of electron-positron pairs we take into account only the curvature radiation of primary electrons and its absorption in magnetic field. It is assumed that some fraction of electron-positron pairs may be created in bound state that can later be photoionized by thermal photons from star surface.


2002 ◽  
Vol 565 (1) ◽  
pp. 482-499 ◽  
Author(s):  
Peter L. Gonthier ◽  
Michelle S. Ouellette ◽  
Joel Berrier ◽  
Shawn O’Brien ◽  
Alice K. Harding
Keyword(s):  

1997 ◽  
Vol 290 (1) ◽  
pp. 49-58 ◽  
Author(s):  
J. Miyazaki ◽  
F. Takahara
Keyword(s):  

2009 ◽  
Vol 27 (10) ◽  
pp. 3755-3764 ◽  
Author(s):  
A. V. Koustov ◽  
G. Ya. Khachikjan ◽  
R. A. Makarevich ◽  
C. Bryant

Abstract. Variation of the cross polar cap potential (CPCP) with the interplanetary electric field (IEF), the merging electric field EKL, the Polar Cap North (PCN) magnetic index, and the solar wind-magnetosphere coupling function EC of Newell et al. (2007) is investigated by considering convection data collected by the Super Dual Auroral Radar Network (SuperDARN) in the Northern Hemisphere. Winter and summer observations are considered separately. All variations considered show close to linear trend at small values of the parameters and tendency for the saturation at large values. The threshold values starting from which the non-linearity was evident were estimated to be IEF*~EKL*~3 mV/m, PCN*~3–4, and EC*~1.5×104. The data indicate that saturation starts at larger values of the above parameters and reaches larger (up to 10 kV) saturation levels during summer. Conclusions are supported by a limited data set of simultaneous SuperDARN observations in the Northern (summer) and Southern (winter) Hemispheres. It is argued that the SuperDARN CPCP saturation levels and the thresholds for the non-linearity to be seen are affected by the method of the CPCP estimates.


2009 ◽  
Vol 27 (3) ◽  
pp. 1139-1152 ◽  
Author(s):  
S. E. Pryse ◽  
E. L. Whittick ◽  
A. D. Aylward ◽  
H. R. Middleton ◽  
D. S. Brown ◽  
...  

Abstract. Electric potential patterns obtained by the SuperDARN radar network are used as input to the Coupled Thermosphere-Ionosphere-Plasmasphere model, in an attempt to improve the modelling of the spatial distribution of the ionospheric plasma at high latitudes. Two case studies are considered, one under conditions of stable IMF Bz negative and the other under stable IMF Bz positive. The modelled plasma distributions are compared with sets of well-established tomographic reconstructions, which have been interpreted previously in multi-instrument studies. For IMF Bz negative both the model and observations show a tongue-of-ionisation on the nightside, with good agreement between the electron density and location of the tongue. Under Bz positive, the SuperDARN input allows the model to reproduce a spatial plasma distribution akin to that observed. In this case plasma, unable to penetrate the polar cap boundary into the polar cap, is drawn by the convective flow in a tongue-of-ionisation around the periphery of the polar cap.


2020 ◽  
Author(s):  
Elizabeth Donegan-Lawley ◽  
Alan Wood ◽  
Gareth Dorrian ◽  
Alexandra Fogg ◽  
Timothy Yeoman ◽  
...  

<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>


2000 ◽  
Vol 177 ◽  
pp. 433-434
Author(s):  
Jaroslaw Dyks ◽  
Bronislaw Rudak

AbstractWithin the framework of a single polar cap model we calculate the energy dependence of phase separation between two peaks in the gamma-ray lightcurve of the Vela pulsar. Results are confronted with EGRET data (Kanbach 1999).


2021 ◽  
Author(s):  
Amalie Ø. Hovland ◽  
Kjellmar Oksavik ◽  
Jone P. Reistad ◽  
Marc R. Hairston

<p>This multi-instrument case study investigates the electrodynamics surrounding polar cap auroral arcs. A long-lasting auroral arc is observed in the high latitude dusk-sector at ~80° Apex latitude in the northern hemisphere. Ion drift measurements from the SSIES system on the DMSP spacecraft have been combined with multiple ground-based observations. Line of sight velocity data from three polar latitude high-frequency Super Dual Auroral Radar Network (SuperDARN) radars show mesoscale structure in the ionospheric convection in the region surrounding the arc. The convection electric field in this region is modelled using a Spherical Elementary Convection Systems (SECS) technique, using curl-free basis functions only. The result is a regional model of the ionospheric convection based on the fairly dense and distributed flow observations and the curl-free constraint. The model is compared to optical data of the auroral arc from two high latitude Redline Emission Geospace Observatory (REGO) all-sky imagers as well as UV images and particle measurements from the DMSP spacecraft to describe the local electrodynamics in the vicinity of the high latitude arc throughout the event.</p>


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