Sunlit cleft and polar cap ionospheric currents determined from rocket-borne magnetic field, plasma, and electric field observations

1979 ◽  
Vol 84 (A11) ◽  
pp. 6458 ◽  
Author(s):  
F. Primdahl ◽  
J.K. Walker ◽  
F. Spangslev ◽  
J.K. Olesen ◽  
U. Fahleson ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Field Observations ◽  
Polar Cap ◽  
Ionospheric Currents

scholarly journals Search for magnetically quiet CHAMP polar passes and the characteristics of ionospheric currents during the dark season

2006 ◽  
Vol 24 (11) ◽  
pp. 2997-3009 ◽  
Author(s):  
P. Ritter ◽  
H. Lühr
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Transverse Field ◽  
Transverse Component ◽  
Local Times ◽  
Time Interval ◽  
Polar Regions ◽  
Ionospheric Currents ◽  
Ionospheric Conductivity ◽  
Field Modelling

Abstract. The magnetic activity at auroral latitudes is strongly dependent on season. During the dark season, when the solar zenith angle in the polar region is larger than 100° at all local times, the ionospheric conductivity is much reduced, and generally low activity is encountered. These time intervals are of special interest for the main field modelling, because then the geomagnetic field readings, in particular the field magnitude, are only slightly affected by ionospheric currents. Based on CHAMP data, this study examines how these quiet periods are reflected in the different magnetic field components. The peak FAC density is used as a possible proxy for the deviation of the total field. As a second option, the transverse field component, which is aligned with the auroral oval, is investigated, because it presents a measure for the FAC total current. Correlation analyses with the scalar residuals are performed and both proxies are tested for their suitability of predicting the intensity of the auroral electrojet during the dark polar seasons. The indicators based on the local FAC strength or on the amplitude of the transverse component show a reasonable correlation with the electrojet intensity for these periods, but fail when limited to small amplitudes. The predictability improves considerably if the time sector is limited to dayside hours (08:00–16:00 MLT). As the activity at high latitudes is strongly controlled by the solar wind input, we also consider IMF quantities which may support very quiet conditions. Correlations of the magnetic field scalar residuals with the merging electric field are strongest if only passes in the dayside sector are considered. Best selection results for quiet passes are obtained by combining four conditions: dark season, small average merging electric field, Em<0.8 mV/m, absence of peak values of Em>1.2 mV/m during a time interval of 40 min centred at the polar crossing, and limitation to the dayside sector (08:00–16:00 MLT). The set of quiet polar passes identified by these criteria may be used beneficially in crustal field modelling of the polar regions.

scholarly journals Global MHD Simulation of the Weak Southward IMF Condition for Different Time Resolutions

2021 ◽  
Vol 8 ◽  
Author(s):  
Kyung Sun Park
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Three Dimensional ◽  
Slow Solar Wind ◽  
Polar Cap ◽  
Plasma Properties ◽  
Simulation Results ◽  
Field Lines ◽  
The Impact

We performed high-resolution three-dimensional global MHD simulations to determine the impact of weak southward interplanetary magnetic field (IMF) (Bz = −2 nT) and slow solar wind to the Earth’s magnetosphere and ionosphere. We considered two cases of differing, uniform time resolution with the same grid spacing simulation to find any possible differences in the simulation results. The simulation results show that dayside magnetic reconnection and tail reconnection continuously occur even during the weak and steady southward IMF conditions. A plasmoid is generated on closed plasma sheet field lines. Vortices are formed in the inner side of the magnetopause due to the viscous-like interaction, which is strengthened by dayside magnetic reconnection. We estimated the dayside magnetic reconnection which occurred in relation to the electric field at the magnetopause and confirmed that the enhanced electric field is caused by the reconnection and the twisted structure of the electric field is due to the vortex. The simulation results of the magnetic field and the plasma properties show quasi-periodic variations with a period of 9–11 min between the appearances of vortices. Also the peak values of the cross-polar cap potential are both approximately 50 kV, the occurrence time of dayside reconnections are the same, and the polar cap potential patterns are the same in both cases. Thus, there are no significant differences in outcome between the two cases.

scholarly journals High-altitude polar cap electric field responses to southward turnings of the interplanetary magnetic field

1998 ◽  
Vol 103 (A11) ◽  
pp. 26533-26545 ◽  
Author(s):  
N. E. Turner ◽  
D. N. Baker ◽  
T. I. Pulkkinen ◽  
H. J. Singer ◽  
F. Mozer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
High Altitude ◽  
Interplanetary Magnetic Field ◽  
Polar Cap

scholarly journals Comment on Invariability of relationship between the polar cap magnetic activity and geoeffective interplanetary electric field by Troshichev et al. (2011)

2020 ◽  
Author(s):  
Peter Stauning
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Interplanetary Magnetic Field ◽  
Magnetic Activity ◽  
The Arctic ◽  
Polar Cap ◽  
Antarctic Research Institute ◽  
Scaling Parameters ◽  
Antarctic Research ◽  
Research Institute

Abstract. In the publication Troshichev et al. (2006) on the Polar Cap (PC) indices, PCN (North) and PCS (South), an error was made by using components of the Interplanetary Magnetic Field (IMF) in their Geocentric Solar Ecliptic (GSE) representation instead of the prescribed Geocentric Solar Magnetosphere (GSM) representation for calculations of index scaling parameters in the version AARI_1998-2001 (named AARI#3) issued from the Arctic and Antarctic Research Institute (AARI) in St Petersburg, Russia. The mistake has caused a trail of incorrect relations and wrong conclusions extending since 2006 up to now (2020). The authors of the publication commented here, Troshichev, Podorozhkina, Janzhura (2011): Invariability of relationship between the polar cap magnetic activity and geoeffective interplanetary electric field, Ann. Geophys., 29, 1479-1489, state that they have used scaling parameters of the (invalid) AARI#3 PC index version in their work but have substituted parameters from the more recent AARI_1995-2005 (AARI#4) version instead. The mingling of PC index versions have resulted in erroneous illustrations in their Figs. 1, 2, 3, 6, 7, and 8 and the issuing of non-substantiated statements.

scholarly journals Disturbed vertical E×B plasma drifts in the equatorial F2 region at solar minimum deduced from observed NmF2 and hmF2 variations

1996 ◽  
Vol 14 (7) ◽  
pp. 733-743 ◽  
Author(s):  
A. V. Mikhailov ◽  
M. Förster ◽  
T. Y. Leschinskaya
Keyword(s):  
Magnetic Field ◽  
Theoretical Model ◽  
Electric Field ◽  
Solar Minimum ◽  
Strong Dependence ◽  
Field Observations ◽  
Model Calculations ◽  
Equatorial Station ◽  
Plasma Drift ◽  
Model Predictions

Abstract. Ground-based ionosonde and magnetic-field observations on the equatorial station Huancayo, ESRO4 neutral-composition measurements, and theoretical model calculations were used to analyze disturbed E×B vertical plasma drift during the phase of solar minimum in 1973. Vertical drifts calculated for disturbed days do not show the systematic decrease often mentioned in publications, and demonstrate strong dependence on IMF-Bz changes. It is confirmed with the help of our drift calculations that Bz turnings to a northward direction result in a decrease (up to reversal) of normal Sq (eastward during daytime and westward at nighttime) in the zonal component of electric field. Southward Bz excursions enhance normal Ey both in daytime and nighttime hours. Model predictions of Ey\\'s reaction to IMF-Bz changes are discussed.

scholarly journals Testing the Electrodynamic Method to Derive Height-Integrated Ionospheric Conductances

2020 ◽  
Author(s):  
Daniel Weimer ◽  
Thom Edwards
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Joule Heating ◽  
Orientation Angle ◽  
Ground Level ◽  
Ionospheric Currents ◽  
Poynting Flux ◽  
Electric Potentials ◽  
Dipole Tilt

Abstract. We have used empirical models for electric potentials and the magnetic fields in both space and on the ground to obtain maps of the height-integrated Pedersen and Hall ionospheric conductivities at high latitudes. This calculation required use of both "curl-free" and "divergence-free" components of the ionospheric currents, with the former obtained from magnetic fields that are used in a model of the field-aligned currents. The second component is from the equivalent current, usually associated with Hall currents, derived from the ground-level magnetic field. Conductances were calculated for varying combinations of the Interplanetary magnetic field (IMF) magnitude and orientation angle, as well as the dipole tilt angle. The results show that reversing the sign of the Y component of the IMF produces substantially different conductivity patterns. The Hall conductivities are largest on the dawn side in the upward, Region 2 field-aligned currents. Low electric field strengths in the Harang discontinuity lead to inconclusive results near midnight. Calculations of the Joule heating, obtained from the electric field and both components of the ionospheric current, are compared with the Poynting flux in space. The maps show some differences, while their integrated totals match to within 1 %. Some of the Poynting flux that enters the polar cap is dissipated as Joule heating within the auroral ovals, where the conductivity is greater.

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