North-South Asymmetry in Geomagnetic Activity during the Epoch 1964-1984.

Rangarajan, Govindan

doi:10.5636/jgg.43.613

Cited by 6 publications

(5 citation statements)

References 5 publications

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“…So, the interplanetary medium and the terrestrial magnetic field respond to most of solar parameters and their evolution, and any change for activity of these solar parameters between the northern and southern hemispheres may reflect another change on the interplanetary parameters and the geomagnetic indices. Studies by Rangarajan [16] revealed that the sun's northern hemisphere is, almost always, geomagnetically more active, on the average of about 20%, than the southern hemisphere. This enhancement activity may be attributed to the inverse relationship between the geomagnetic activity and the strength of the magnetic field.…”

Section: Resultsmentioning

confidence: 99%

North-South Asymmetry of the Interplanetary Magnetic Field Magnitude and the Geomagnetic Indices

El‐Borie

Abdel-Halim

El-Monier

2016

IJAA

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Data of the daily interplanetary magnetic field (IMF), and the geomagnetic indices (aa, Ap, Kp, and DST) have been used to examine the asymmetry between the solar field north and south of the heliospheric current sheet, over the period (1975-2013). It important to note that during the positive polarity epochs: (T) refers to Toward the South of the heliospheric current sheet (Southern Hemisphere), and (A) refers to Away from North of the heliospheric current sheet (Northern Hemisphere). While, during the negative polarity epochs the opposite will be happened. The present study finds no clear indication of the presence of north-south asymmetry in the field magnitude, and also there is no magnetic solar cycle dependence that is evident. During the considered period, the north-south asymmetry for the considered parameters reaches maximum values around the declining phase or near to the minimum of the solar cycle. The geomagnetic indices have a clear asymmetry during the positive solar magnetic polarity period (qA > 0) and have a northern dominance during cycles (22 & 23) and southern dominance during cycles (21 & 24). From the power spectrum density, the considered parameters showed significant peaks which appeared in the north-south asymmetry but the 10.7 yr solar cycle was absent. In addition, the main periodicity of the asymmetry may be 5.2, 4.0 and 3.3 years that exist in the parameters with higher confidence levels. Finally, one can conclude that the asymmetry of the interplanetary parameters and the geomagnetic indices may provide multiple causes for producing the observed asymmetric modulations of cosmic rays.

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Section: Resultsmentioning

confidence: 99%

North-South Asymmetry of the Interplanetary Magnetic Field Magnitude and the Geomagnetic Indices

El‐Borie

Abdel-Halim

El-Monier

2016

IJAA

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“…In the earlier paper (RANGARAJAN, 1991), the asymmetry in geomagnetic activity was defined as: Fig. 1(b).…”

Section: Discussionmentioning

confidence: 99%

“…In a recent study, RANGARAJAN (1991) carried out a detailed analysis of the north-south asymmetry in geomagnetic activity for the epoch 1964-84 and showed that though the northern hemisphere has, in general, greater magnitude of geomagnetic activity leading to a positive asymmetry, there are several occasions when the southern hemisphere is more active as evidenced by the magnitude of the negative asymmetry.…”

Section: Introductionmentioning

confidence: 99%

Response of the Sq and Equatorial Electrojet Variations to the North-South Asymmetry in Geomagnetic Activity.

Rangarajan

Dhar

1992

J. geomagn. geoelec

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The nature of the diurnal variation of the ionospheric component of the equatorial electrojet and planetary Sq field is studied using the horizontal intensity data of a suitable triad of stations in the Indian zone separately for conditions of enhanced geomagnetic activity in the northern and southern hemispheres. It is shown that the influence of the NorthSouth asymmetry is manifested in distinct fashions in the diurnal patterns of Sq and jet. Disturbance dynamo caused by even moderate geomagnetic activity appears to alter the shape and structure of the equatorial electrojet and the planetary Sq current systems. Conspicuous absence of the difference when the asymmetry in geomagnetic activity vanishes confirms the perceptible influence of the N-S asymmetry on the ionospheric current system at low and equatorial latitudes.

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“…Geomagnetic activity indices are important products derived from observatory magnetometer time series (e.g., Mayaud, 1980; Rangarajan, 1989). Among the oldest and most frequently used are local K indices (e.g., Menvielle & Berthelier, 1991).…”

Section: Geomagnetic Indicesmentioning

confidence: 99%

The March 1940 Superstorm: Geoelectromagnetic Hazards and Impacts on American Communication and Power Systems

et al. 2023

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An analysis is made of geophysical records of the 24 March 1940, magnetic storm and related reports of interference on long‐line communication and power systems across the contiguous United States and, to a lesser extent, Canada. Most long‐line system interference occurred during local daytime, after the second of two storm sudden commencements and during the early part of the storm's main phase. The high degree of system interference experienced during this storm is inferred to have been due to unusually large‐amplitude and unusually rapid geomagnetic field variation, possibly driven by interacting interplanetary coronal‐mass ejections. Geomagnetic field variation, in turn, induced geoelectric fields in the electrically conducting solid Earth, establishing large potential differences (voltages) between grounding points at communication depots and transformer substations connected by long transmission lines. It is shown that March 1940 storm‐time communication‐ and power‐system interference was primarily experienced over regions of high electromagnetic surface impedance, mainly in the upper Midwest and eastern United States. Potential differences measured on several grounded long lines during the storm exceeded 1‐min resolution voltages that would have been induced by the March 1989 storm. In some places, voltages exceeded American electric‐power‐industry benchmarks. It is concluded that the March 1940 magnetic storm was unusually effective at inducing geoelectric fields. Although modern communication systems are now much less dependent on long electrically conducting transmission lines, modern electric‐power‐transmission systems are more dependent on such lines, and they, thus, might experience interference with the future occurrence of a storm as effective as that of March 1940.

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North-South Asymmetry in Geomagnetic Activity during the Epoch 1964-1984.

Cited by 6 publications

References 5 publications

North-South Asymmetry of the Interplanetary Magnetic Field Magnitude and the Geomagnetic Indices

North-South Asymmetry of the Interplanetary Magnetic Field Magnitude and the Geomagnetic Indices

Response of the Sq and Equatorial Electrojet Variations to the North-South Asymmetry in Geomagnetic Activity.

The March 1940 Superstorm: Geoelectromagnetic Hazards and Impacts on American Communication and Power Systems

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