An explanation for anomalous equatorial ionospheric electric fields associated with a northward turning of the interplanetary magnetic field

Kelley, M. C.; Fejer, Bela G.; Gonzales, C. A.

doi:10.1029/gl006i004p00301

Cited by 433 publications

(409 citation statements)

References 14 publications

Supporting

Mentioning

394

Contrasting

Order By: Relevance

“…A sharp northward turning after prolonged southward IMF orientation causes an abrupt drop of convection electric field, and thus, it is preferable to create overshielding because the shielding electric field usually takes time to increase or decay depending on the charge accumulation [Kelley et al, 1979]. On the other hand, a very gradual northward turning after prolonged southward IMF orientation is not preferable for overshielding because there may be enough time allowing the shielding electric field to adjust to cancel the convection electric field.…”

Section: The Shape Of Imf Northward Turningmentioning

confidence: 99%

“…[3] To explain the polarity reversal of the equatorial ionospheric electric field associated with northward turning of the IMF, Kelley et al [1979] recognized it as an overshielding effect and attributed it to a drop of the convection electric field. For this scenario, the typical historical pattern of overshielding is that the undershielding caused by the southward IMF occurs first, and then overshielding happens when the IMF turns northward.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The transition to overshielding after sharp and gradual interplanetary magnetic field northward turning

Wei

Wan

et al. 2011

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Overshielding is referred to a shielding status, during which the dawnward shielding electric field dominates over the duskward penetration electric field in the inner magnetosphere, typically appearing when the interplanetary magnetic field (IMF) suddenly turns northward after a prolonged southward orientation. It is expected that the transition to overshielding after IMF northward turning can be affected by the shape of northward turning (sharp or gradual). Moreover, the initial shielding status (undershielding or goodshielding) prior to the transition may also have influence on the transition. Here we analyze two groups of cases, in which the transitions appear after sharp (duration less than 5 min) and gradual (duration more than 30 min) northward turning. Each group includes two cases, in which the transition initiated from undershielding and goodshielding. These cases show that (1) the beginning of the transition to overshielding coincides with sharp IMF northward turning but appears in the midst of gradual IMF northward turning; (2) the transition from goodshielding to overshielding is always associated with convection electric field drop and/or polar cap shrinkage, regardless of the shape of IMF northward turning; and (3) the typical solar wind condition in which the IMF suddenly turns northward after a prolonged southward orientation is neither a necessary condition nor a sufficient condition for overshielding. Furthermore, we will discuss the effect of substorm processes on overshielding.

show abstract

Section: The Shape Of Imf Northward Turningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The transition to overshielding after sharp and gradual interplanetary magnetic field northward turning

Wei

Wan

et al. 2011

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…Many papers have described a secondary maximum in ESF occurrence in the post-midnight period (Abdu et al, , 1983Fejer et al, 1999;Hysell and Burcham, 2002;MacDougall et al, 1998). During periods of high geomagnetic activity, electric fields can penetrate to low latitudes and cause the equatorial electric field to reverse in the post-midnight period, which is a source of ESF during periods of high geomagnetic activity (Kelley et al, 1979b;Fejer et al, 1999). Hysell and Burcham (2002) divides the pre-sunrise ESF into two categories.…”

Section: Equatorial Spread-fmentioning

confidence: 99%

“…Storm-time effects can cause variations in the equatorial electric fields through changes in the global wind system, penetrating electric fields (e.g., Nishida et al, 1966;Vasyliunas, 1970;Kelley et al, 1979b), and disturbance dynamo winds driven by Joule heating (e.g., Blanc and Richmond, 1980). It is unlikely that the effects we are observing are due to penetrating electric fields since there are no rapid variations in the interplanetary electric field for the days we have examined.…”

Section: Interpretation and Variation Of Upliftsmentioning

confidence: 99%

Observations and modeling of post-midnight uplifts near the magnetic equator

et al. 2006

Self Cite

View full text Add to dashboard Cite

Abstract. We report here on post-midnight uplifts near the magnetic equator. We present observational evidence from digital ionosondes in Brazil, a digisonde in Peru, and other measurements at the Jicamarca Radio Observatory that show that these uplifts occur fairly regularly in the post-midnight period, raising the ionosphere by tens of kilometers in the most mild events and by over a hundred kilometers in the most severe events. We show that in general the uplifts are not the result of a zonal electric field reversal, and demonstrate instead that the uplifts occur as the ionospheric response to a decreasing westward electric field in conjunction with sufficient recombination and plasma flux. The decreasing westward electric field may be caused by a change in the wind system related to the midnight pressure bulge, which is associated with the midnight temperature maximum. In order to agree with observations from Jicamarca and Palmas, Brazil, it is shown that there must exist sufficient horizontal plasma flux associated with the pressure bulge. In addition, we show that the uplifts may be correlated with a secondary maximum in the spread-F occurrence rate in the post-midnight period. The uplifts are strongly seasonally dependent, presumably according to the seasonal dependence of the midnight pressure bulge, which leads to the necessary small westward field in the post-midnight period during certain seasons. We also discuss the enhancement of the uplifts associated with increased geomagnetic activity, which may be related to disturbance dynamo winds. Finally, we show that it is possible using simple numerical techniques to estimate the horizontal plasma flux and the vertical drift velocity from electron density measurements in the post-midnight period.

show abstract

“…[2] It is well-established that electric fields of magnetospheric origin can penetrate to mid-and low-latitudes during magnetically active periods [Kelley et al, 1979;Spiro et al, 1988;Fejer and Scherliess, 1995;Basu et al, 2001;Huang et al, 2005] and that these fields can substantially modify low-to mid-latitude ionospheric plasma properties. However, determination of the impact of penetration electric fields on the ionosphere based on a selfconsistent electrodynamic model has been lacking [Huba et al, 2003;Maruyama et al, 2005].…”

Section: Introductionmentioning

confidence: 99%

Simulation study of penetration electric field effects on the low‐ to mid‐latitude ionosphere

Huba¹,

Joyce²,

Sazykin³

et al. 2005

Geophysical Research Letters

102

109

View full text Add to dashboard Cite

[1] The first self-consistent study of the impact of storm-time penetration electric fields on the low-to midlatitude ionosphere is presented. The inner magnetosphere is described by the Rice Convection Model (RCM) and the ionosphere is described by the Naval Research Laboratory (NRL) code SAMI3. The codes are coupled electrodynamically through the electrostatic potential equation, and the storm is modeled via changes in the polar cap potential. Neutral wind driven electric fields are estimated from the Fejer/Scherliess quiet time model. It is found that temporal changes in the polar cap potential produce electric fields that modify the F region equatorial E Â B drift velocities: the velocities increase in the daytime and decrease in the nighttime by up to a factor of two. This causes the total electron content (TEC) in the daytime, mid-latitude ionosphere to increase by up to 35%. In addition, the 'fountain effect' is enhanced in the postsunset period. Citation: Huba, J. D., G. Joyce, S. Sazykin, R. Wolf, and R. Spiro (2005), Simulation study of penetration electric field effects on the low-to mid-latitude ionosphere,

show abstract

An explanation for anomalous equatorial ionospheric electric fields associated with a northward turning of the interplanetary magnetic field

Cited by 433 publications

References 14 publications

The transition to overshielding after sharp and gradual interplanetary magnetic field northward turning

The transition to overshielding after sharp and gradual interplanetary magnetic field northward turning

Observations and modeling of post-midnight uplifts near the magnetic equator

Simulation study of penetration electric field effects on the low‐ to mid‐latitude ionosphere

Contact Info

Product

Resources

About