Sudden impulses at low‐latitude stations: Steady state response for northward interplanetary magnetic field

Russell, C. T.; Ginskey, M.; Petrinec, S. M.

doi:10.1029/93ja02288

Cited by 104 publications

(170 citation statements)

References 20 publications

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“…Recently, in a statistical study, Francia et al (1999) analyzed some events occurring during northward IMF conditions and showed that the geomagnetic field horizontal component H at a low-latitude station (L'Aquila) responds very well to the SW pressure variations on a time scale of few minutes. The amplitude of the geomagnetic response was found to be linearly related to the change in the square root of the SW dynamic pressure, and its average amplitude (∼13 nT/(nPa) 1/2 ) is comparable with the values found by Russell et al (1994) and Russell and Ginskey (1995) at low and subauroral latitudes in the analysis of the sudden impulse (SI) response to the passage of interplanetary shocks. Moreover, the amplitude of the response was found to depend on local time, with greater values around local noon and midnight and a pronounced minimum during the local morning.…”

Section: Introductionsupporting

confidence: 69%

Geomagnetic field fluctuations during the passage at the Earth’s orbit of the tail of the 15–16 July 2000 ejecta

2002

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Abstract. In this work we present the analysis of the geomagnetic field fluctuations observed at different ground stations (approximately along two latitudinal arrays, separated by several hours in local time) during the passage at the Earth's orbit of the tail of the 15-16 July 2000 coronal ejecta. The time interval of interest is characterized by northward interplanetary magnetic field conditions and several changes in the solar wind dynamic pressure. We found at all stations, both in the local morning and in the local evening, simultaneous and highly coherent waves at the same discrete frequencies (∼1.8 and ∼3.6 mHz) and suggest a possible interpretation in terms of global compressional modes driven by an impulsive variation of the solar wind pressure. Along the array situated in the morning sector, at the highest latitudes, the higher frequency mode seems to couple with the local field line resonance; on the other hand, along the array situated in the evening sector, the characteristics of the observed fluctuations suggest that the highest latitude station could be located at the footprint of open field lines. Our results also show that solar wind pressure variations observed during the recovery phase of the storm do not find correspondence in the geomagnetic field variations, regardless of local time and latitude; conversely, some hours later continuous solar wind pressure variations find a close correspondence in the geomagnetic field variations at all stations.

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Section: Introductionsupporting

confidence: 69%

Geomagnetic field fluctuations during the passage at the Earth’s orbit of the tail of the 15–16 July 2000 ejecta

2002

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“…We observed that the geomagnetic field I I . which is more complex than that observed for Sis at low latitude (with a single maximum around local noon [Russell et al, 1994]). Rather, it is very similar, although with a smaller excursion between minimum and maximum values, to the diurnal pattern observed at subauroral latitudes for Sis, which was interpreted in terms of superimposed effects of magnetopause currents and ionospheric Hall currents [Russell and Ginskey, 1995].…”

Section: Summary and Discussionmentioning

confidence: 58%

Geomagnetic response at low latitude to continuous solar wind pressure variations during northward interplanetary magnetic field

Francia¹,

Lepidi²,

Villante³

et al. 1999

J. Geophys. Res.

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“…For southward IMF the opposite situation occurs due to the enhancement of the tail current and Region 1 current systems and to the triggering of substorms in the magnetotail [Russell et al, 1994b]. When the IMF is northward and the solar wind dynamic pressure suddenly increases, the increase in the H component magnetic field measured by low-and middle-latitude stations is governed by the currents on the magnetopause [Russell et al, 1994b] [Russell and Ginskey, 1995, Figure 7] which is somewhat similar to the case under study here, except that our observations are at middle-and low-latitudes. Russell and Ginskey [1995] postulated a steady or slowly varying current system associated with twin cells of largescale convection and apparently restricted to the dayside.…”

Section: Introductionmentioning

confidence: 99%

Special features of the September 24–27, 1998 storm during high solar wind dynamic pressure and northward interplanetary magnetic field

Clauer¹,

Alexeev²,

Belenkaya³

et al. 2001

J. Geophys. Res.

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Abstract. The geomagnetic storm on September 24 -27, 1998, was initiated by a sudden compression of the magnetosphere in response to the solar wind dynamic pressure pulse. Simultaneous with the pressure increase, the interplanetary magnetic field (IMF) became strongly northward. Several unexpected magnetospheric responses to this sudden impulse were observed. First, for • 30 min following the sudden impulse, the entire auroral oval became active and thick, while the polar cap area decreased to less than 1/2 of its original size. The second unusual observation associated with the sudden impulse is the global magnetic perturbation measured by low-latitu de magnetic stations. The field shows an asymmetric increase in the axial component (parallel to the dipole axis) with the strongest enhancement measured on the night side and at local magnetic noon the perturbation is small or slightly negative. This is very unusual since sudden compressions are generally measured by low-latitude stations to have the largest enhancement of the field on the dayside. The main phase of the geomagnetic storm begins in the second hour on September 25, 1998, following the southward turning of the IMF. The auroral oval becomes thin and moves equatorward increasing the polar cap area by more than a factor of 3. The theoretical analysis presented in this paper suggests that the response to the sudden impulse is an electrodynamic effect produce d by a "transition" current system in response to the northward turning of the IMF.

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Sudden impulses at low‐latitude stations: Steady state response for northward interplanetary magnetic field

Cited by 104 publications

References 20 publications

Geomagnetic field fluctuations during the passage at the Earth’s orbit of the tail of the 15–16 July 2000 ejecta

Geomagnetic field fluctuations during the passage at the Earth’s orbit of the tail of the 15–16 July 2000 ejecta

Geomagnetic response at low latitude to continuous solar wind pressure variations during northward interplanetary magnetic field

Special features of the September 24–27, 1998 storm during high solar wind dynamic pressure and northward interplanetary magnetic field

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