Interplanetary Electric Field Ey Research Articles

Midlatitude postsunset plasma bubbles observed over Europe during intense storms in April 2000 and 2001

AbstractPlasma bubbles are prevalent features of the equatorial/low‐latitude ionosphere which are seldom observed at middle and high latitudes. Understanding the influence of geomagnetic storms on plasma bubbles' migration to higher latitudes is an important space weather topic, since a geomagnetic storm is an important phenomenon of space weather. This paper reports on the first observations of postsunset/evening midlatitude plasma bubbles in the European sector during the main phase of severe storms (Dst≤−200 nT) on 6 April 2000 and 11 April 2001. Plasma depletions observed in Global Navigation Satellite System total electron content measurements are confirmed with those observed from in situ Defense Meteorological Satellite Program ion density measurements. The results show that the plasma bubbles were migrating north at virtual speeds of 400 m/s and on each of the storm days they extended as far north as ∼42° (geographic latitude). It is estimated that the plasma bubbles may have grown to a maximum apex height of approximately 4000 km. During the time of bubble occurrence, the evening midlatitude plasma was enhanced and the equatorial ionization anomaly extended to European midlatitudes. In addition, evidence of the upward plasma motion was found in ionosonde hmF2 and h'F measurements, while the interplanetary electric field Ey was enhanced. This was found to suggest that the possible mechanism for the enhancement of midlatitude plasma and subsequent midlatitude plasma bubbles occurrence was the eastward penetration electric field associated with Bz southward turning.

Interplanetary drivers of daytime penetration electric field into equatorial ionosphere during CIR-induced geomagnetic storms

Observations based on the magnetometer data of the response of the daytime equatorial electric field to the geomagnetic storms induced by corotating interaction regions (CIRs) during 2007–2010 reveal many events of striking long duration of multiple short-lived prompt penetration electric fields (PPEFs). The PPEFs essentially occurred in the main phase of the storms, which are associated with the ring current and magnetic reconnection of the southward z-component of the interplanetary magnetic field (IMF Bz) in relation to the Alfvén waves. The behaviors of the electric field penetration during the storms are consistent with the shielding theory. Particularly, the PPEF is found to be complex due to transient variations in the solar wind dynamic pressure (SWDP) and the IMF Bz in the CIRs. The PPEF is temporary suppressed for about an hour under a shock in association with a drop in the SWDP. The interplanetary electric field Ey is the main driver of the PPEFs, when the solar wind speed, SWDP, and the symmetric ring current are nearly constant, even in the recovery phase. The PPEF is allowed under the condition of high and variable SWDP. The shocks with a northward IMF Bz shield the PPEFs when the SWDP is nearly constant. The partial ring current is strongest in the large and northward IMF Bz, where the shielding effect is greater than the undershielding caused by the large SWDP. The results may provide an important step to study equatorial and low latitude ionospheric electrodynamics in the solar minimum conditions.

Dependence of plasmaspheric hiss on solar wind parameters and geomagnetic activity and modeling of its global distribution

AbstractAccurate knowledge of the global distribution of plasmaspheric hiss is essential for the radiation belt modeling because it provides a direct link to understanding the radiation belt loss in the slot region. In this paper, we study the dependence of hiss activity on solar wind parameters and geomagnetic activity indices using Time History of Events and Macroscale Interactions during Substorms hiss measurements made from 1 July 2008 to 30 June 2012 based on a correlation analysis. We find that hiss amplitudes are well correlated with the preceding solar wind speed VSW, interplanetary magnetic field (IMF) BZ, and interplanetary electric field (IEF) EY with delay times of 5–6 h for VSW and 3–4 h for IMF BZ and IEF EY, while the best correlation with the geomagnetic indices, AE, Kp, and SYM‐H, occurs at a delay time of 2–3 h for AE and SYM‐H and 3–4 h for Kp. Of the solar wind parameters, the dawn‐to‐dusk component of IEF EY yields the best correlation with the variation of hiss wave. More interestingly, the global distribution of hiss waves shows a significant dependence on the VSW and IMF BZ: the most intense hiss region tends to occur at prenoon sector for a more southward IMF BZ, while the tendency is opposite with increasing VSW. This implies different origins of hiss activity. Also, we employ an artificial neural network technique to develop models of the global distribution of hiss amplitudes based on the solar wind parameters and geomagnetic indices. The solely solar wind parameter‐based model generally results in a higher correlation between the measured and modeled hiss amplitudes than any other models based on the geomagnetic indices. Finally, we use the solar wind parameter‐based model to investigate hiss activity during storm events by distinguishing between coronal mass ejection‐driven storms and corotating interaction region‐driven storms. The result shows that in spite of the differences in the behavior of solar wind parameters between the two storm groups, the different types of storms lead to the similar evolution of hiss waves in overall appearance even though the detailed behavior of hiss activations are different.

Storm time electric fields in the equatorial ionosphere observed near the dusk meridian

We compare the dynamics of plasma drifts (VP) and ionospheric electric fields (EI), measured near the dusk meridian at the magnetic equator by the Defense Meteorological Satellite Program (DMSP) F13 satellite, with those of the dawn‐to‐dusk component of the interplanetary electric field (IEF) Ey during four large magnetic storms. Presented data indicate that during the main phase of the magnetic storms when the interplanetary magnetic field (IMF) had a southward component, VP had upward and westward components that ranged up to 120 and 210 m s−1. The corresponding eastward and upward components of EI were approximately 5% and 10% of Ey. The persistence of eastward EI for many hours indicates that electric field shielding of the inner magnetosphere is ineffective during prolonged periods of southward IMF. During periods of northward IMF (Ey < 0) ionospheric responses depended on prior history. No ionospheric response is apparent after strong northward IMF turnings preceded by geomagnetic quiet. If they occurred after a long southward interval, EI often had westward and downward components. The polarity of the zonal component of EI remained well correlated with that of Ey for up to 21 h during periods of slowly varying IMF. Phenomena associated with southward IMF periods are consistent with models that allow for prolonged penetration electric field from high latitudes superposed on those of the Sq current system. However, it is not understood why the remarkable correspondence between the polarities of the zonal component of EI and the IEF Ey occurs during northward IMF. In some Ey < 0 periods, the vertical component of EI remained upward. DMSP detections of upward EI (westward VP) during periods of Ey < 0 are not predicted by existing models.