Response of Thermospheric Nightglow Emissions Over the Magnetic Equator to Prompt Penetration Electric Field Events

2019 ◽  
Vol 124 (7) ◽  
pp. 5918-5935 ◽  
Author(s):  
C. Vineeth ◽  
A. Ajesh ◽  
T. K. Pant ◽  
J. M. Ruohoniemi
Keyword(s):  
Electric Field ◽  
Magnetic Equator ◽  
Prompt Penetration Electric Field

scholarly journals Responses of equatorial anomaly to the October-November 2003 superstorms

2005 ◽  
Vol 23 (3) ◽  
pp. 693-706 ◽  
Author(s):  
B. Zhao ◽  
W. Wan ◽  
L. Liu
Keyword(s):  
Electric Field ◽  
Current Theory ◽  
Peak Height ◽  
Shielding Effect ◽  
Electron Content ◽  
Equatorial Anomaly ◽  
Total Electron ◽  
Prompt Penetration Electric Field ◽  
Autumnal Equinox ◽  
American Region

Abstract. The responses of Equatorial Ionization Anomaly (EIA) to the superstorms of October-November 2003 were investigated using the total electron content (TEC) measured with global positioning system (GPS) receivers in China, Southeast Asia, Australian (CSAA), and the American regions. Enhanced EIA was seen to be correlated with the southward turning of the interplanetary magnetic field Bz. In both the CSAA and American regions, EIA was intensified, corresponding to a large increase in the F-layer peak height (hmF2) measured by ionosonde and digisonde at middle and equatorial latitudes. However, the enhanced EIA was shown to be more significant during the daytime in the American region, which was associated with a series of large substorms when Bz was stable southward. The prompt penetration electric field and the wind disturbances dynamo electric field are suggested to be responsible for this observation according to current theory, although some features cannot be totally decipherable. Both the ionogram and magnetometer data show the existence of a weak shielding effect whose effect still needs further study. A clear asymmetric ionospheric response was shown in our TEC observations, even though it was only one month after autumnal equinox. The southern EIA crest was totally obliterated on 29 and 30 October in the CSAA region and on 31 October in the American region. Ion temperatures from the Defense Meteorological Satellite Program (DMSP) spacecraft revealed that the unequal energy injection at the polar region might be the reason for this effect. It is concluded that different physical processes have varying degrees of importance on the evolution of EIA in the CSAA and American regions.

Comparison of different techniques to estimate the direction of the Poynting vector of EMIC emissions

2021 ◽  
Author(s):  
Benjamin Grison ◽  
Ondrej Santolik
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Poynting Vector ◽  
Source Region ◽  
Transverse Component ◽  
Equatorial Region ◽  
Magnetic Equator ◽  
Ion Temperature ◽  
Temperature Anisotropy ◽  
Single Plane

<p>Electromagnetic Ion Cyclotron (EMIC) waves usually grow in the inner magnetosphere from hot ion temperature anisotropy. The main source region is located close to the magnetic equator and there is a secondary EMIC source region off the magnetic equator in the dayside magnetosphere. The source region can be identified using measurements of the Poynting vector direction.</p><p>The Poynting vector is ideally derived from the measurement of 3 components of the wave electric field and 3 components of components of the wave magnetic field. However, spinning spacecraft often have only two long mutually perpendicular electric antennas in the spin plane, deployed by the centrifugal force. The third antenna, when present, is usually shorter owing to difficulties of deploying a antenna along the spin axis.</p><p>Estimations of the Poynting vector from measurements of three magnetic field components and two electric field components can be obtained assuming the presence of a single plane wave (and thus perpendicularity of the electric field and the magnetic field vectors, according to the Faraday’s law), following the method developed by Loto'aniu et al. (2005). Applying this method to Cluster data, Allen et al. (2013) found the presence of bidirectional EMIC emissions off the magnetic equatorial region.</p><p>Another technique proposed earlier by Santolík et al. (2001) considers the phase shift estimation between the electric signals from each antenna and synthetic perpendicular magnetic field components obtained from the three-dimensional measurements. The method is based on cross-spectral estimates in the frequency domain and can be used to estimate sign of each component of the Poynting vector. Using this technique Grison et al. (2016) showed the importance of the transverse component of the EMIC emissions far from the source region.</p><p>We compare these methods for different events to check how the results of these two techniques differ. We also discuss what we can learn about the EMIC source region from these measurements.</p>

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

2009 ◽  
Vol 27 (9) ◽  
pp. 3523-3536 ◽  
Author(s):  
K. Z. Zaka ◽  
A. T. Kobea ◽  
P. Assamoi ◽  
O. K. Obrou ◽  
V. Doumbia ◽  
...  
Keyword(s):  
Electric Field ◽  
Magnetic Storm ◽  
Current Flow ◽  
Ionospheric Disturbance ◽  
Equatorial Region ◽  
Magnetic Equator ◽  
Magnetic Disturbance ◽  
Magnetic Signature ◽  
Low Latitudes ◽  
Latitudinal Profile

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.

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

2006 ◽  
Vol 24 (5) ◽  
pp. 1317-1331 ◽  
Author(s):  
M. J. Nicolls ◽  
M. C. Kelley ◽  
M. N. Vlasov ◽  
Y. Sahai ◽  
J. L. Chau ◽  
...  
Keyword(s):  
Electric Field ◽  
Magnetic Equator ◽  
Occurrence Rate ◽  
Plasma Flux ◽  
Numerical Techniques ◽  
Field Reversal ◽  
Radio Observatory ◽  
Density Measurements ◽  
Vertical Drift ◽  
Spread F

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.

scholarly journals Satellite drag effects due to uplifted oxygen neutrals during super magnetic storms

2017 ◽  
Vol 24 (4) ◽  
pp. 745-750 ◽  
Author(s):  
Gurbax S. Lakhina ◽  
Bruce T. Tsurutani
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Magnetic Storms ◽  
Magnetic Equator ◽  
Unit Mass ◽  
Satellite Drag ◽  
Oxygen Ions ◽  
Drag Forces ◽  
Upward Moving ◽  
Leo Satellite

Abstract. During intense magnetic storms, prompt penetration electric fields (PPEFs) through E  ×  B forces near the magnetic equator uplift the dayside ionosphere. This effect has been called the dayside super-fountain effect. Ion-neutral drag forces between the upward moving O+ (oxygen ions) and oxygen neutrals will elevate the oxygen atoms to higher altitudes. This paper gives a linear calculation indicating how serious the effect may be during an 1859-type (Carrington) superstorm. It is concluded that the oxygen neutral densities produced at low-Earth-orbiting (LEO) satellite altitudes may be sufficiently high to present severe satellite drag. It is estimated that with a prompt penetrating electric field of ∼ 20 mV m−1 turned on for 20 min, the O atoms and O+ ions are uplifted to 850 km where they produce about 40-times-greater satellite drag per unit mass than normal. Stronger electric fields will presumably lead to greater uplifted mass.

scholarly journals Signatures of Sudden Storm Commencement on the equatorial thermospheric dayglow

2019 ◽  
Vol 9 ◽  
pp. A31
Author(s):  
Sukumarn N.G.K. Sumod ◽  
Tarun K. Pant ◽  
Asokan P. Ajesh
Keyword(s):  
Solar Wind ◽  
Electric Field ◽  
Sudden Increase ◽  
Abrupt Increase ◽  
Equatorial Station ◽  
Compression Phase ◽  
F Region ◽  
Ram Pressure ◽  
Airglow Emissions ◽  
Prompt Penetration Electric Field

It has been observed that the OI 630.0 nm dayglow emission over a dip equatorial station, Trivandrum (8.5° N, 77° E, dip 0.5° N), India registered an abrupt increase of ~ 2000 R during the compression phase of the magnetosphere as dictated by a sudden increase in solar wind ram pressure. Furthermore, an unusual depletion of these emissions has been observed during the eastward interplanetary electric field (IEF), concomitant with southward excursion of IMF Bz. The ionosonde and magnetometer observations confirmed the effects of prompt penetration electric field (PPEF). Associated with the eastward PPEF, formation of F3 layers were also noticed. These unique results, which emphasize the effect of Sudden Storm Commencement/IEF on these equatorial daytime airglow emissions are discussed in context of changes in the equatorial zonal electric field and F region height variations associated with polar/auroral activities due to the magnetosphere-ionosphere coupling.

Sign in / Sign up

Export Citation Format

Share Document