Some features of Pc5 pulsations in the period range 180-300 sec.

Gupta, Jagdish C.

doi:10.5636/jgg.28.359

Cited by 4 publications

(5 citation statements)

References 18 publications

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“…Surprisingly, although one might expect the 4 -10 mHz band to reveal higher frequency field line oscillations at subauroral and/or lower latitudes, very little power in this frequency range was observed during or after these storms at any of these stations. This latitude dependence, consistent with that presented by Gupta [1975Gupta [ , 1976, will be explored further in a subsequent paper.…”

Section: Observations During the March 1998 Stormsupporting

confidence: 81%

“…Numerous studies have focused on the local time distribution of these long‐period, solar wind‐controlled ULF waves. In the outer magnetosphere, both ground‐based observations [e.g., Gupta , 1975, 1976; Engebretson et al , 1998] and satellite‐based studies [e.g., Kokubun et al , 1989; Anderson et al , 1990; Nosé et al , 1995; Lessard et al , 1999] have shown that they exhibit maximum occurrence and amplitude in the dawn‐to‐noon local time sector, and that in this region, they are predominantly narrow in bandwidth.…”

Section: Introductionmentioning

confidence: 99%

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Characterizing the long‐period ULF response to magnetic storms

et al. 2003

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This study presents an analysis of long‐period ULF wave power observed at 44 ground magnetometer stations in the western hemisphere, at latitudes from the equator to the polar caps, during the magnetic storm intervals of May 1997, March 1998, May 1998, September 1998, and October 1998 identified by the GEM research community. Comparison of the long‐period pulsations (in the Pc5 frequency range) observed on the ground to the solar wind velocity and solar wind pressure observed by the WIND satellite confirms previous results that high solar wind velocity correlates well with increased Pc5 power. Although some variability was evident among the five storms, solar wind pressure and variability in velocity or pressure exhibited considerably weaker correlations. Each storm exhibited narrow‐band Pc5 wave activity during the recovery phase, but only in the dawn‐noon sector at each site. During the main phase, and at all other local times during the recovery phase, wave activity was broadband. The strongest Pc5 power was observed at frequencies above 2 mHz at stations in the auroral zone and poleward and below 2 mHz at stations at middle and low latitudes. Comparison to published time profiles of energetic electrons at geosynchronous orbit suggests that if ULF wave activity is responsible for the initial energization of these electrons, broadband activity rather than narrowband (Pc5) waves must play the dominant role. Our data cannot rule out, however, the importance of narrowband waves in providing additional energization during the recovery phase.

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Section: Observations During the March 1998 Stormsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Characterizing the long‐period ULF response to magnetic storms

et al. 2003

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“…The Pc5 pulsation appears for the period of 08:10–08:35 UT (17:10–17:35 LT), when Mineyama is at dusk. Previous studies reported that the Pc5 amplitude is as large as 50–100 nT near a subauroral latitude, but it drastically decreases to <10 nT at a low latitude (<40° GMLAT) (e.g., Gupta, 1976; Lee et al., 2007). The observation in Figure 6b agrees well with the results of the previous studies.…”

Section: Experimental Measurement Of Geomagnetic Fields With MI Senso...mentioning

confidence: 96%

Application of Magneto‐Impedance (MI) Sensor to Geomagnetic Field Measurements

Nosé

Kawano²,

Aoyama³

2022

JGR Space Physics

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The magneto-impedance (MI) effect was discovered about 30 years ago and a microsize magnetic sensor utilizing this effect has become commercially available. We make some modifications to the commercially available MI sensors to cover the dynamic range of the geomagnetic field. The total cost of three MI sensors for the two horizontal components and one vertical component including the modification is approximately one-third of the standard price of triaxial fluxgate magnetometer sensors. For the period of 30 March to 27 April 2018, we conducted experimental observations of geomagnetic field variations with the MI sensor magnetometer (MIM) at the Mineyama observatory, which is located about 100 km northwest of Kyoto, Japan. Data obtained with the MIM are compared with those from the fluxgate magnetometer (FGM) that has been working at the observatory. Results show that the MIM can record geomagnetic field variations such as geomagnetic storm, solar quiet variations, low-latitude positive bays, storm sudden commencement, and long-period geomagnetic pulsations with a peak-to-peak amplitude of ≤1 nT that is also detected with the FGM. Power spectra of the geomagnetic field variations measured with the MIM and FGM are almost the same. It is found that the MIM has a larger temperature drift than the FGM. The present study reveals that the MIM is comparable to the FGM in measuring the geomagnetic field variations in a period from a few tens of seconds to a few hours and is useful for researches in upper atmospheric physics or space physics. NOSÉ ET AL.

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“…For example, using analog data, GUPTA (1975) analysed only the Pc5 pulsations in the 300-600 sec period (1.6-3.3mHz). Similarly, GUPTA (1976) examined only the 180-300 sec (3.3-5.6mHz) Pc5 pulsations. The rationale behind Gupta's work is that "the period range of Pc5's is much too wide and that the characteristics of pulsations in the higher period range differ to some extent from those in the lower end of the range" (GUPTA, 1976).…”

Section: Introductionmentioning

confidence: 99%

“…Similarly, GUPTA (1976) examined only the 180-300 sec (3.3-5.6mHz) Pc5 pulsations. The rationale behind Gupta's work is that "the period range of Pc5's is much too wide and that the characteristics of pulsations in the higher period range differ to some extent from those in the lower end of the range" (GUPTA, 1976). Using digital data, LAM and RosTOKER (1978) and LAM (1980) analysed the higher frequency spectral band and H.-L. LAM the lower frequency spectral band of Pc5 separately.…”

Section: Introductionmentioning

confidence: 99%

A possible classification of Pc5 geomagnetic pulsations into two sub-groups(Pc5A and Pc5B) based on spectral structure.

Lam

1989

J. geomagn. geoelec

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Ground magnetic data recorded in the auroral zone station at Fort Churchill, Canada (FCC) during 1985 were used to study the spectral content of Pc5 magnetic pulsations. It was found that spectral peaks tend to group into two separate bands of 1-3mHz and 3-6mHz. The power in both bands appears to be linearly related to global planetary geomagnetic activity as represented by the Ap index. While pulsations in both bands show a 27-day recurrence tendency, only intense pulsations in the low frequency band (1-3mHz) seem to recur in the morning a few days after an initial enhancement. On the other hand, pulsations in the high frequency band (3-6mHz) always have low amplitudes in the afternoon. In general, the low frequency band activity is more intense than the high frequency band activity . It is suggested that Pc5 pulsations can be classified into two sub-groups, with pulsations in the low frequency band of 1-3mHz classified as Pc5A and those in the high frequency band of 3-6mHz classified as Pc5B. Probably, Pc5A is associated with the "ringing" of the large-scale three-dimensional magnetospheric and ionospheric current systems and Pc5B is due to field line resonance. This classification scheme would provide a convenient mean of expressing and recognizing the frequency content of Pc5 events.

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Some features of Pc5 pulsations in the period range 180-300 sec.

Cited by 4 publications

References 18 publications

Characterizing the long‐period ULF response to magnetic storms

Characterizing the long‐period ULF response to magnetic storms

Application of Magneto‐Impedance (MI) Sensor to Geomagnetic Field Measurements

A possible classification of Pc5 geomagnetic pulsations into two sub-groups(Pc5A and Pc5B) based on spectral structure.

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