scholarly journals Velocity of small-scale auroral ionospheric current systems over Indian Antarctic station Maitri

2002 ◽  
Vol 111 (1) ◽  
pp. 51-62
Author(s):  
Girija Rajaram ◽  
A. N. Hanchinal ◽  
R. Kalra ◽  
K. Unnikrishnan ◽  
K. Jeeva ◽  
...  
Keyword(s):  
Small Scale ◽  
Ionospheric Current ◽  
Current Systems

scholarly journals Evaluation of the geometry of ionospheric current systems related to rapid geomagnetic variations

2004 ◽  
Vol 22 (1) ◽  
pp. 63-72 ◽  
Author(s):  
S. V. Apatenkov ◽  
V. A. Sergeev ◽  
R. Pirjola ◽  
A. Viljanen
Keyword(s):  
Dynamic Pressure ◽  
Auroral Oval ◽  
Auroral Zone ◽  
Middle Part ◽  
Magnetic Storms ◽  
Geomagnetically Induced Currents ◽  
Geomagnetic Variations ◽  
Ionospheric Current ◽  
Solar Wind Parameters ◽  
Current Systems

Abstract. To learn about the geometry and sources of the ionospheric current systems which generate strong geomagnetically induced currents, we categorize differential equivalent current systems (DEC) for events with strong dB/dt by decomposing them into the contributions of electrojet-type and vortex-type elementary systems. By solving the inverse problem we obtain amplitudes and locations of these elementary current systems. One-minute differences of the geomagnetic field values at the IMAGE magnetometer network in 1996–2000 are analysed to study the spatial distributions of large dB/dt events. The relative contributions of the two components are evaluated. In particular, we found that the majority of the strongest dB/dt events (100–1000nT/min) appear to be produced by the vortex-type current structures and most of them occur in the morning LT hours, probably caused by the Ps6 pulsation events associated with auroral omega structures. For strong dB/dt events the solar wind parameters are shifted toward strong (tens nT) southward IMF, enhanced velocity and dynamic pressure, in order for the main phase of the magnetic storms to occur. Although these events appear mostly during magnetic storms when the auroral oval greatly expands, the area of large dB/dt stays in the middle part of the auroral zone; therefore, it is connected to the processes taking part in the middle of the magnetosphere rather than in its innermost region populated by the ring current. Key words. Geomagnetism and paleomagnetism (rapid time variations) – Ionosphere (auroral ionosphere; ionospheric disturbances)

Geomagnetic Crochets and Associated Ionospheric Current Systems

Radio Science ◽  
1971 ◽  
Vol 6 (2) ◽  
pp. 139-164 ◽  
Author(s):  
A. D. Richmond ◽  
S. V. Venkateswaran
Keyword(s):  
Ionospheric Current ◽  
Current Systems

scholarly journals April 2000 geomagnetic storm: ionospheric drivers of large geomagnetically induced currents

2003 ◽  
Vol 21 (3) ◽  
pp. 709-717 ◽  
Author(s):  
A. Pulkkinen ◽  
A. Thomson ◽  
E. Clarke ◽  
A. McKay
Keyword(s):  
Geomagnetic Storm ◽  
Large Scale ◽  
Regional Scale ◽  
Normal Operation ◽  
Technological Systems ◽  
Geomagnetically Induced Currents ◽  
Ionospheric Currents ◽  
Ionospheric Current ◽  
Induced Currents ◽  
Current Systems

Abstract. Geomagnetically induced currents (GIC) flowing in technological systems on the ground are a direct manifestation of space weather. Due to the proximity of very dynamic ionospheric current systems, GIC are of special interest at high latitudes, where they have been known to cause problems, for example, for normal operation of power transmission systems and buried pipelines. The basic physics underlying GIC, i.e. the magnetosphere – ionosphere interaction and electromagnetic induction in the ground, is already quite well known. However, no detailed study of the drivers of GIC has been carried out and little is known about the relative importance of different types of ionospheric current systems in terms of large GIC. In this study, the geomagnetic storm of 6–7 April 2000 is investigated. During this event, large GIC were measured in technological systems, both in Finland and in Great Britain. Therefore, this provides a basis for a detailed GIC study over a relatively large regional scale. By using GIC data and corresponding geomagnetic data from north European magnetometer networks, the ionospheric drivers of large GIC during the event were identified and analysed. Although most of the peak GIC during the storm were clearly related to substorm intensifications, there were no common characteristics discernible in substorm behaviour that could be associated with all the GIC peaks. For example, both very localized ionospheric currents structures, as well as relatively large-scale propagating structures were observed during the peaks in GIC. Only during the storm sudden commencement at the beginning of the event were large-scale GIC evident across northern Europe with coherent behaviour. The typical duration of peaks in GIC was also quite short, varying between 2–15 min.Key words. Geomagnetism and paleo-magnetism (geomagnetic induction) – Ionosphere (ionospheric disturbances) – Magnetospheric physics (storms and substorms)

scholarly journals Dipolar elementary current systems for ionospheric current reconstruction at low and middle latitudes

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Heikki Vanhamäki ◽  
Astrid Maute ◽  
Patrick Alken ◽  
Huixin Liu
Keyword(s):  
Synthetic Data ◽  
Field Measurements ◽  
Ionospheric Currents ◽  
Ionospheric Current ◽  
Middle Latitudes ◽  
Field Lines ◽  
Magnetometer Arrays ◽  
Swarm Satellite ◽  
Current Reconstruction ◽  
Current Systems

Abstract The technique of spherical elementary current systems (SECS) is a powerful way to determine ionospheric and field-aligned currents (FAC) from magnetic field measurements made by low-Earth-orbiting satellites, possibly in combination with magnetometer arrays on the ground. The SECS method consists of two sets of basis functions for the ionospheric currents: divergence-free (DF) and curl-free (CF) components, which produce poloidal and toroidal magnetic fields, respectively. The original CF SECS are only applicable at high latitudes, as they build on the assumption that the FAC flow radially into or out of the ionosphere. The FAC at low and middle latitudes are far from radial, which renders the method inapplicable at these latitudes. In this study, we modify the original CF SECS by including FAC that flow along dipolar field lines. This allows the method to be applied at all latitudes. We name this method dipolar elementary current systems (DECS). Application of the DECS to synthetic data, as well as Swarm satellite measurements are carried out, demonstrating the good performance of this method, and its applicability to studies of ionospheric current systems at low and middle latitudes.

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