A study of magnetic pulsations in the Indian equatorial region

Jain, A. R.; Srinivasacharya, K. G.

doi:10.1016/0021-9169(75)90078-1

Cited by 9 publications

(3 citation statements)

References 9 publications

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“…Similar enhancements of other classes of shorter period geomagnetic pulsations with daytime (Pi2 and Pc3-4) are clearly established from earlier studies (Jain and Srinivasacharya, 1975;Sastry et al, 1979Sastry et al, , 1983Saka et al, 1988;Sarma et al, 1991;Sarma and Sastry, 1995;Shinohara et al, 1998). It is also known that the equatorial electrojet can have control on other geophysical phenomena.…”

Section: Discussion and Summarysupporting

confidence: 83%

Equatorial enhancement of Pc5–6 magnetic storm time geomagnetic pulsations

et al. 2014

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Geomagnetic Pc5-6 (1-4 mHz) pulsations during three magnetic storms have been analyzed using ground observations at an array of 5 Indian stations ranging from 0.8• to 25• dip latitudes and two pairs of low-latitudes (∼20• )-near equator (∼4-5 • ) stations, located at ∼4 hours to the West and East from this meridian. The pulsations are found to occur as individual wave packets that are characterized by similar spectra at all stations with two dominate bands of frequencies: ∼1.5-2.0 mHz and ∼2.5-4.0 mHz. Very strong daytime equatorial enhancement of the wave intensity has been noted. The higher enhancement is observed near noon while it is reduced towards the morning and evening sectors. The polarization of both frequency bands at the equator is found to be almost linear, mainly along the H -direction. It has been found that the amplitude of the D-component decreased with decrease in the latitude towards the equator. One of the spectral peaks is observed exclusively at the dip equator station and it has been attributed to the generation/amplification of MHD waves by the equatorial electrojet instabilities.The mechanism of day time equatorial enhancement of long period geomagnetic pulsations and the propagation characteristics are discussed.

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Section: Discussion and Summarysupporting

confidence: 83%

Equatorial enhancement of Pc5–6 magnetic storm time geomagnetic pulsations

et al. 2014

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“…At nearequatorial stations monochromatic pulsations with elevated amplitudes are often observed (Tanaka et al, 2004). This effect of the "equatorial enhancement of ULF waves" was noticed many decades ago for dayside Pc3-5 waves (Jain and Srinivasacharya, 1975) and nighttime Pi2 pulsations (Osaki et al, 1996;Yumoto, 2001). The equatorial enhancement of ULF waves was $2-3 times as compared with more distant stations (Zanandrea et al, 2004).…”

Section: Introduction: Possible Mechanisms Of Pi2/pc3 Wave Propagatiomentioning

confidence: 88%

Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations

Cuturrufo

Pilipenko

Heilig

et al. 2015

Advances in Space Research

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We have examined simultaneous ULF activity in the Pi2 and Pc3 bands at the near-equatorial magnetic stations in South America from SAMBA and MAGDAS arrays and low-orbiting CHAMP satellite during its passage over this meridional network. At the nighttime, both Pi2 and Pc3 waves in the upper ionosphere and on the ground are nearly of the same magnitude and in-phase. At the same time, the daytime Pc3 pulsations on the ground and in space are nearly out-of-phase. Comparison of observational results with the theoretical notions on the MHD wave interaction with the system ionosphere-atmosphere-ground suggests that nighttime low-latitude Pi2 and Pc3 wave signatures are produced by magnetospheric fast compressional mode. The daytime near-equatorial Pc3 waves still resist a quantative interpretation. These waves may be produced by a combination of two mechanisms: compressional mode leakage through the ionosphere, and by oscillatory ionospheric current spreading towards equatorial latitudes.

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“…It is well known that amplitudes of SEC's in H are enhanced during daytime in the equatorial region (SUGIURA, 1953;FORBUSH and VESTINE, 1955;MAEDA and YAMAMOTO, 1960;SRINIVASAMURTHY, 1960;RASTOGI et al, 1964). The diurnal variation of such enhancement in the Indian region was studied by BHARGAVA (1967), TRIVEDI and RASTOGI (1968), SASTRI and JAYAKAR (1970) and JAIN and SRINIVASACHARYA (1976). In a recent paper, MAYAUD (1975) has shown that the yearly number of SSC events are well correlated with the yearly averages of sunspot number and that at a low latitude station (Colaba-Alibag, dip lat.…”

Section: Introductionmentioning

confidence: 99%

Equatorial enhancement of SSC amplitudes: Solar activity dependence and effect of electric field.

Jain

Srinivasacharya

1976

J. geomagn. geoelec

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Characteristics of SSC amplitude at low and equatorial latitudes are studied using the data of 332 events observed simultaneously at three stations in the Indian region during the period [1958][1959][1960][1961][1962][1963][1964][1965][1966][1967][1968][1969][1970][1971][1972][1973]. It is shown that during daytime both SSC amplitude in H and its equatorial enhancement increase with increased solar activity. During nighttime also the SSC amplitudes are found to vary with solar activity. The daytime equatorial enhancement of SSC's, which is attributed to the currents in the ionospheric E -layer, shows much sharper variation with solar activity than that shown by conductivity in that layer or the jet current intensity. SSC's which occurred during partial counter electrojet events are examined to determine the effect of change in an ambient electric field on their amplitudes. It is found that a westward ambient electric field leads to a reduction in the equatorial enhancement.

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A study of magnetic pulsations in the Indian equatorial region

Cited by 9 publications

References 9 publications

Equatorial enhancement of Pc5–6 magnetic storm time geomagnetic pulsations

Equatorial enhancement of Pc5–6 magnetic storm time geomagnetic pulsations

Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations

Equatorial enhancement of SSC amplitudes: Solar activity dependence and effect of electric field.

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