Observations of interactions between interplanetary and geomagnetic fields

Burch, J. L.

doi:10.1029/rg012i003p00363

Cited by 99 publications

(33 citation statements)

References 108 publications

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“…1 and 2). This suggestion is corroborated by studies that have shown a strong positive correlation between the southward IMF component (B z ) and a variety of geomagnetic and auroral activity indices (Arnoldy, 1971;Foster et al, 1971;Rostoker et al, 1972;Burch, 1974;Garrett et al, 1974;Murayama and Hakamada, 1975). Figure 3b shows the plot of the H component on 10 and 11 June 1993 (solid line) (period No 1) compared with those of the reference quiet day levels (dashed line), over the African sector (UT=LT).…”

Section: Variations Of the Solar Wind Parameters And The Magnetic Indsupporting

confidence: 62%

Latitudinal profile of the ionospheric disturbance dynamo magnetic signature: comparison with the DP2 magnetic disturbance

et al. 2009

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Abstract. During magnetic storms, the auroral electrojets intensification affects the thermospheric circulation on a global scale. This process which leads to electric field and current disturbance at middle and low latitudes, on the quiet day after the end of a storm, has been attributed to the ionospheric disturbance dynamo (Ddyn). The magnetic field disturbance observed as a result of this process is the reduction of the H component amplitude in the equatorial region which constitutes the main characteristic of the ionospheric disturbance dynamo process, associated with a westward electric current flow. The latitudinal profile of the Ddyn disturbance dynamo magnetic signature exhibits an eastward current at mid latitudes and a westward one at low latitudes with a substantial amplification at the magnetic equator. Such current flow reveals an "anti-Sq" system established between the mid latitudes and the equatorial region and opposes the normal Sq current vortex. However, the localization of the eastward current and consequently the position and the extent of the "anti-Sq" current vortex changes from one storm to another. Indeed, for a strong magnetic storm, the eastward current is well established at mid latitudes about 45 • N and for a weak magnetic storm, the eastward current is established toward the high latitudes (about 60 • N), near the Joule heating region, resulting in a large "anti-Sq" current cell. The latitudinal profile of the Ddyn disturbance as well as the magnetic disturbance DP2 generated by the mechanism of prompt penetration of the magnetospheric convection electric field in general, show a weak disturbance at the low latitudes with a substantial amplification at the magnetic equator. Due to the intensity of the storm, the magnitude of the DP2 appears higher than the Ddyn over the American and Asian sector contrary to the African sector.

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Section: Variations Of the Solar Wind Parameters And The Magnetic Indsupporting

confidence: 62%

Latitudinal profile of the ionospheric disturbance dynamo magnetic signature: comparison with the DP2 magnetic disturbance

et al. 2009

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“…These studies have established the importance of such interplanetary parameters as the north-south magnetic field component (B0, the solar wind speed (V), the interplanetary magnetic field (IMF), magnitude (B), and various combinations of these parameters (see reviews by Burch, 1974;Akasofu, 1977;and Russell, 1979). These studies have established the importance of such interplanetary parameters as the north-south magnetic field component (B0, the solar wind speed (V), the interplanetary magnetic field (IMF), magnitude (B), and various combinations of these parameters (see reviews by Burch, 1974;Akasofu, 1977;and Russell, 1979).…”

Section: Introductionmentioning

confidence: 99%

Solar wind control of auroral zone geomagnetic activity

Clauer¹,

McPherron²,

Searls³

et al. 1981

Geophysical Research Letters

129

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An empirical analysis of solar wind‐magnetosphere energy coupling functions is reported. Using the technique of linear prediction filtering with 2.5 minute data, we examine the relationship of auroral zone geomagnetic activity to solar wind power input functions which depend on the solar wind quantities VB², VBs, or V²Bs. In this analysis a least squares prediction filter or impulse response function which relates a solar wind power function to an auroral zone geomagnetic index is designed directly from the data. We find that the computed impulse response functions have the characteristics of a low pass filter with a time delay which may be dependent on the strength of the energy input. While the AL index is reasonably well related to the solar wind energy functions, the AU index shows a substantially poorer relationship. In addition, high frequency variations of the auroral indices and some substorm expansions are not predictable with solar wind information alone, suggesting that internal magnetospheric processes partially control the AL index. We also find that the ϵ parameter which depends on VB² in the solar wind has a poorer relationship to auroral zone geomagnetic activity than a power parameter having a VBs solar wind dependence.

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“…Evans and Stone [1972] place this latitude between 75 ø and 80 ø near local noon and 75 ø and 76 ø near local midnight. From these high latitudes the geomagnetic field lines have been 'blown' far to the nightside of the earth, downwind, to form the outer regions of the magnetospheric tail where merging of the interplanetary and geomagnetic fields is most likely to occur [Burch, 1974]. We have demonstrated that the polar sector effects are strongest well above the 74 ø invariant latitude and thius within the open field line region.…”

mentioning

confidence: 99%

Polar cap geomagnetic field responses to solar sector changes

Campbell¹

1976

J. Geophys. Res.

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I made a computerized analysis of digitized magnetograms from Alert, Thule, Resolute Bay, Mould Bay, and Godhavn for 1965 and from Thule and Vostok for 1967 to determine the characteristic features of the day‐to‐day geomagnetic field variations related to the interplanetary solar sector field direction. Higher invariant latitude stations showed the sector effects most clearly. A sector‐related phase shift in the characteristic diurnal variation of the field occurred principally for the dayside vertical geomagnetic component. The amplitude of this diurnal variation was related to Ap and could not be used to identify the sector direction. The quiet nighttime level of field Z component rose and fell on days when the interplanetary magnetic field was directed toward or away from the sun, respectively. When a station's base level field was determined from quiet magnetospheric conditions by using days with low values of Dst and AE indices, the mean field level of the Z component for the whole day increased or decreased (often over 100 γ) from this level as the solar sector direction was toward or away, respectively. With respect to the earth's main field direction the southern polar station field level changes were opposite those at the northern stations. This level shift corresponded with the two solar field directions during the summer months at polar stations for about 70% of the days in 1965 and 88% of the days in 1967. In 1967 the standoff locations of the magnetopause and magnetoshock boundaries were about 1 RE more distant from the earth for the average toward sector days than for the away sector days.

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Observations of interactions between interplanetary and geomagnetic fields

Cited by 99 publications

References 108 publications

Latitudinal profile of the ionospheric disturbance dynamo magnetic signature: comparison with the DP2 magnetic disturbance

Latitudinal profile of the ionospheric disturbance dynamo magnetic signature: comparison with the DP2 magnetic disturbance

Solar wind control of auroral zone geomagnetic activity

Polar cap geomagnetic field responses to solar sector changes

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