Penetration characteristics of the interplanetary electric field to the daytime equatorial ionosphere

Abstract

[1] Using 8 years of ionospheric drift measurements from the low-latitude JULIA (Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere) radar and the solar wind and interplanetary magnetic field data from the ACE (Advance Composition Explorer) satellite, we study the characteristics of the prompt penetration of electric fields to the equatorial ionosphere. A large database allowed us to bring out statistically significant characteristics of electric field penetration as a function of frequency. The coherence between the interplanetary electric field (IEF) and the equatorial electric field (EEF) peaks around a 2-hour period with a maximum magnitude squared coherence of 0.6. The coherence is slightly higher (0.7) on magnetically active (Ap > 20) days. The cross-phase spectra between the ACE and JULIA variations, after elimination of the propagation delay, have negligible values. Correspondingly, the time shift between IEF and EEF is less than 5 minutes at all periods. We also find that the penetration efficiency is highest during local noon, as compared with that of morning and evening hours. The coherence is lower for days with high solar flux values. We find that the penetration of electric fields into the equatorial ionosphere has no significant dependence on season and on the polarity of IMF B z . We propose a transfer function between IEF and EEF, which was validated on synthetic as well as observed IEF data. The use of this transfer function decreases the misfit of a climatological model with the measured equatorial electric field by 27%.Citation: Manoj, C., S. Maus, H. Lühr, and P. Alken (2008), Penetration characteristics of the interplanetary electric field to the daytime equatorial ionosphere,

Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

“…1b), which is comparable to super-storm values (e.g., Kelley et al 2003;Huang et al 2005;Fejer et al 2007;Balan et al 2010). It is known that, at the first approximation, the IEF Ey is positively correlated with the zonal equatorial electric field on the local dayside and negatively correlated on the local nightside (e.g., Manoj et al 2008Manoj et al , 2013. Thus, for a positive IEF, the effect on the zonal electric field is primarily eastward during daytime and westward during nighttime.…”

“…The PPEF occur during the IMF Bz negative interval, and about 5-12 % of the associated eastward interplanetary electric field (IEF) can penetrate into the ionosphere (e.g., Kelley et al 2003;Huang et al 2007;Manoj et al 2008Manoj et al , 2013Verkhoglyadova et al 2008). A sudden northward Bz turning from steady southward direction can also lead to anomalous reversal of the zonal equatorial electric fields Fejer et al 1979), while the penetration can be as efficient as during Bz negative events (Manoj et al 2008;Tsurutani et al 2008). Since the IEF Ey is calculated using the MHD approximation from the IMF Bz and the Vx component of the solar wind speed as -Bz*Vx (http:// omniweb.gsfc.nasa.gov), the northward/positive IMF Bz presumes occurrence of the westward electric fields on the dayside and eastward electric fields on the nightside.…”

Penetration of the convection and overshielding electric fields to the equatorial ionosphere during a quasiperiodic DP 2 geomagnetic fluctuation event

“…Substorm-associated electric fields are an important issue to be studied in a separate paper. The excellent correspondence in both dynamic pressure and IMF variations with the DP 2 fluctuations validates the time shift of 32 min if we Manoj et al [2008] found that the time delay between the IEF and the equatorial electric field was less than 5 min on the basis of the statistical analysis of ionospheric drift measurements from the Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere radar. Consequently, the e-EJ was driven by the dawn-to-dusk convection electric field caused by the southward IMF, while the w-EJ must be caused by the over- shielding electric field associated with the R2 FACs [Nopper and Carovillano, 1978;Peymirat et al, 2000].…”

Evidence of short spatial variability of the equatorial electrojet at close longitudinal separation

“…The first global model of the EEJ was deduced from the POGO (1967 to 1970) satellite observations (Onwumechilli and Agu 1980). Using the CHAMP satellite data, the longitudinal differences in the behavior of the EEJ influenced by tidal zonal winds (Luhr et al 2012;Hausler et al 2013) and other interplanetary fields (Manoj et al 2008) were revealed. A systematic study of the EEJ characteristics using all the data from the Oersted, CHAMP, and SAC-C satellites obtained during the years (1999 to 2006) was used to construct the equatorial electrojet climatological model (EEJM-2.0) to reflect the day-to-day variability of electrojet using the input parameters of longitude, local time, and season and solar flux.…”