skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Role of IMF B y in the prompt electric field disturbances over equatorial ionosphere during a space weather event

Abstract

On 7 January 2005 (Ap=40) prompt penetration electric field perturbations of opposite polarities were observed over Thumba and Jicamarca on a few occasions during 13:45–16:30 UT. However, the electric field was found to be eastward during 14:45–15:30 UT over both Thumba and Jicamarca contrary to the general expectation wherein opposite polarities are expected at nearly antipodal points. On closer scrutiny, three important observational features are noticed during 14:10–15:15 UT. First, during 14:10–14:45 UT, despite increasing southward interplanetary magnetic field (IMF) B z condition, the already westward electric field over Thumba weakened (less westward) while the eastward electric field over Jicamarca intensified (more eastward). Second, the electric field not only became anomalously eastward over Thumba but also got intensified further during 14:45–15:00 UT similar to Jicamarca. Third, during 15:00–15:15 UT, despite IMF B z remaining steadily southward, the eastward electric field continued to intensify over Thumba but weakened over Jicamarca. It is suggested that the changes in IMF B y component under southward IMF B z condition are responsible for skewing the ionospheric equipotential patterns over the dip equator in such a way that Thumba came into the same DP2 cell as that of Jicamarca leading to anomalous electric field variations.more » Magnetic field measurements along the Indian and Jicamarca longitude sectors and changes in high-latitude ionospheric convection patterns provide credence to this proposition. Therefore, in conclusion, the present investigation shows that the variations in IMF B y are fundamentally important to understand the prompt penetration effects over low latitudes.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]
  1. Physical Research Lab., Ahmedabad (India)
  2. Indian Inst. of Geomagnetism, Navi Mumbai (India)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Consortium, Los Alamos, NM (United States)
  4. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Bradley Dept. of Electrical and Computer Engineering
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
National Aeronautic and Space Administration (NASA); National Science Foundation (NSF); USDOE; Department of Space, Government of India
OSTI Identifier:
1402608
Report Number(s):
LA-UR-16-22089
Journal ID: ISSN 2169-9380; TRN: US1703006
Grant/Contract Number:
AC52-06NA25396
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 122; Journal Issue: 2; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 58 GEOSCIENCES; Heliospheric and Magnetospheric Physics; IMF By; Prompt penetration electric field; Equatorial ionosphere; DP2

Citation Formats

Chakrabarty, Dipu, Hui, Debrup, Rout, Diptiranjan, Sekar, R., Bhattacharyya, Archana, Reeves, Geoffrey D., and Ruohoniemi, J. M. Role of IMF By in the prompt electric field disturbances over equatorial ionosphere during a space weather event. United States: N. p., 2017. Web. doi:10.1002/2016JA022781.
Chakrabarty, Dipu, Hui, Debrup, Rout, Diptiranjan, Sekar, R., Bhattacharyya, Archana, Reeves, Geoffrey D., & Ruohoniemi, J. M. Role of IMF By in the prompt electric field disturbances over equatorial ionosphere during a space weather event. United States. doi:10.1002/2016JA022781.
Chakrabarty, Dipu, Hui, Debrup, Rout, Diptiranjan, Sekar, R., Bhattacharyya, Archana, Reeves, Geoffrey D., and Ruohoniemi, J. M. Sat . "Role of IMF By in the prompt electric field disturbances over equatorial ionosphere during a space weather event". United States. doi:10.1002/2016JA022781. https://www.osti.gov/servlets/purl/1402608.
@article{osti_1402608,
title = {Role of IMF By in the prompt electric field disturbances over equatorial ionosphere during a space weather event},
author = {Chakrabarty, Dipu and Hui, Debrup and Rout, Diptiranjan and Sekar, R. and Bhattacharyya, Archana and Reeves, Geoffrey D. and Ruohoniemi, J. M.},
abstractNote = {On 7 January 2005 (Ap=40) prompt penetration electric field perturbations of opposite polarities were observed over Thumba and Jicamarca on a few occasions during 13:45–16:30 UT. However, the electric field was found to be eastward during 14:45–15:30 UT over both Thumba and Jicamarca contrary to the general expectation wherein opposite polarities are expected at nearly antipodal points. On closer scrutiny, three important observational features are noticed during 14:10–15:15 UT. First, during 14:10–14:45 UT, despite increasing southward interplanetary magnetic field (IMF) Bz condition, the already westward electric field over Thumba weakened (less westward) while the eastward electric field over Jicamarca intensified (more eastward). Second, the electric field not only became anomalously eastward over Thumba but also got intensified further during 14:45–15:00 UT similar to Jicamarca. Third, during 15:00–15:15 UT, despite IMF Bz remaining steadily southward, the eastward electric field continued to intensify over Thumba but weakened over Jicamarca. It is suggested that the changes in IMF By component under southward IMF Bz condition are responsible for skewing the ionospheric equipotential patterns over the dip equator in such a way that Thumba came into the same DP2 cell as that of Jicamarca leading to anomalous electric field variations. Magnetic field measurements along the Indian and Jicamarca longitude sectors and changes in high-latitude ionospheric convection patterns provide credence to this proposition. Therefore, in conclusion, the present investigation shows that the variations in IMF By are fundamentally important to understand the prompt penetration effects over low latitudes.},
doi = {10.1002/2016JA022781},
journal = {Journal of Geophysical Research. Space Physics},
number = 2,
volume = 122,
place = {United States},
year = {Sat Feb 04 00:00:00 EST 2017},
month = {Sat Feb 04 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:
  • Before the onset of a geomagnetic storm on 22 January 2012 (Ap = 24), an enhancement in solar wind number density from 10/cm 3 to 22/cm 3 during 0440–0510 UT under northward interplanetary magnetic field (IMF Bz) condition is shown to have enhanced the high-latitude ionospheric convection and also caused variations in the geomagnetic field globally. Some conspicuous changes in ΔX are observed not only at longitudinally separated low-latitude stations over Indian (prenoon), South American (midnight), Japanese (afternoon), Pacific (afternoon) and African (morning) sectors but also at latitudinally separated stations located over high and middle latitudes. The latitudinal variation ofmore » the amplitude of the ΔX during 0440–0510 UT is shown to be consistent with the characteristics of prompt penetration electric field disturbances. Most importantly, the density pulse event caused enhancements in the equatorial electrojet strength and the peak height of the F layer (h mF 2) over the Indian dip equatorial sector. Furthermore, the concomitant enhancements in electrojet current and F layer movement over the dip equator observed during this space weather event suggest a common driver of prompt electric field disturbance at this time. Such simultaneous variations are found to be absent during magnetically quiet days. In the absence of significant change in solar wind velocity and magnetospheric substorm activity, these observations point toward perceptible prompt electric field disturbance over the dip equator driven by the overcompression of the magnetosphere by solar wind density enhancement.« less
  • During periods of southward interplanetary magnetic field (IMF) the authors have examined the relationship between magnetic variations in the central polar cap and the IMF B{sub y} and B{sub z} components. The geomagnetic polar cap index PC that can be used as a measure of the flow across the polar cap has been derived using data from Thule in the IMS period. The results have been compared with IMP 8 measurements of the IMF and the solar wind velocity. The statistical analysis shows that the absolute value of the azimuthal component {vert bar}B{sub y}{vert bar} contributes to the cross-polar capmore » flow in the same manner as the southward component B{sub s}. The relative contributions of {vert bar}B{sub y}{vert bar} and B{sub z} have been examined and compared with the theoretical expression {upsilon}B{sub T} sin{sup 2} {theta}/2 for the merging electric field. It is found that the contribution of {vert bar}B{sub y}{vert bar} compared to B{sub z} is only half as big in the observations as in the theoretical expression. The B{sub y} effect on PC is compared to an earlier reported effect of B{sub y} on the geomagnetic index AL (Murayama et al., 1980) and found to be quite different from this. This is discussed in relation to interpretations in terms of merging site asymmetry.« less
  • This study tries to bring out the fact that storm time substorms can compete and at times significantly contribute to the geomagnetically disturbed time prompt penetration electric field effects on low and equatorial latitudes. Observations of unusual equatorial plasma drift data from Jicamarca Unattended Long-term Investigations of the Ionosphere and Atmosphere during two space weather events show that substorms can induce both eastward and westward penetration electric fields under steady southward interplanetary magnetic field (IMF B z) conditions. During the first event on 2 January 2005, the enhancement of the daytime eastward electric field over Jicamarca due to substorm ismore » found to be comparable with the Sq and interplanetary electric field (IEFy) generated electric fields combined. During the second event on 19 August 2006, the substorm is seen to weaken the daytime eastward field thereby inducing a westward field in spite of the absence of northward turning of IMF B z (overshielding). The westward electric field perturbation in the absence of any overshielding events is observationally sparse and contrary to the earlier results. Further, the substorm-induced field is found to be strong enough to compete or almost nullify the effects of storm time IEFy fields. This study also shows quantitatively that at times substorm contribution to the disturbed time prompt electric fields can be significant and thus should be taken into consideration in evaluating penetration events over low latitudes.« less
  • We have used a high-resolution and time-dependent three-dimensional magnetohydrodynamic (MHD) model to study the interaction between the solar wind and the earth's magnetosphere during intervals when the interplanetary magnetic field (IMF) has both a B/sub y/ component and northward B/sub z/ component. When the IMF is northward, the palsma sheet thickens near the noon-midnight meridian and extends projections into the northern and southern lobes. When projected onto the polar cap, this appears as a narrow channel extending from midnight toward noon. This plasma sheet extension from the nightside toward the dayside shifts toward dawn for B/sub y/<0 and toward duskmore » for B/sub y/<0 and toward dusk for B/sub y/>0. Two types of upward field-aligned currents were found: an arc-shaped current which extends around the auroal zone and a tail lobe region 1 current running almost parallel to the sun-earth line. Like the plasma sheet extension the sun-aligned tail lobe region 1 current moves across the northern polar cap from dusk to dawn when the IMF orientation chagnes from duskward to dawnward during northward IMF. At latitudes north of the region 1 current in the polar cap the currents have the same direction as the region 2 currents (i.e., upward at dawn and downward at dusk). As the IMF orientation changes from northward to dawnward, the currents rotate such that the upward current joins wit the upward region 1 current, while the earthward current expands in the polar region. These magnetospheric features can be well explained by high-latitude merging cells and tail lobe convection cells resulting from antiparallel merging between the northward IMF and the tail field.« less