scholarly journals Equatorial E region electric fields at the dip equator: 1. Variabilities in eastern Brazil and Peru

2016 ◽  
Vol 121 (10) ◽  
pp. 10,220-10,230 ◽  
Author(s):  
J. Moro ◽  
C. M. Denardini ◽  
L. C. A. Resende ◽  
S. S. Chen ◽  
N. J. Schuch
Keyword(s):  
Electric Fields ◽  
Eastern Brazil ◽  
E Region ◽  
Dip Equator

scholarly journals Influence of uncertainties of the empirical models for inferring the E-region electric fields at the dip equator

2016 ◽  
Vol 68 (1) ◽  
Author(s):  
Juliano Moro ◽  
Clezio Marcos Denardini ◽  
Laysa Cristina Araújo Resende ◽  
Sony Su Chen ◽  
Nelson Jorge Schuch
Keyword(s):  
Electric Fields ◽  
Empirical Models ◽  
E Region ◽  
Dip Equator

E region electric fields at the dip equator and anomalous conductivity effects

2013 ◽  
Vol 51 (10) ◽  
pp. 1857-1869 ◽  
Author(s):  
C.M. Denardini ◽  
H.C. Aveiro ◽  
J.H.A. Sobral ◽  
J.V. Bageston ◽  
L.M. Guizelli ◽  
...  
Keyword(s):  
Electric Fields ◽  
E Region ◽  
Dip Equator

scholarly journals Signatures of 2-day wave in the E-region electric fields and their relationship to winds and ionospheric currents

2009 ◽  
Vol 27 (2) ◽  
pp. 631-638 ◽  
Author(s):  
H. C. Aveiro ◽  
C. M. Denardini ◽  
M. A. Abdu
Keyword(s):  
Electric Fields ◽  
Magnetic Activity ◽  
Ionospheric Currents ◽  
Coherent Scatter ◽  
Meridional Winds ◽  
Magnetometer Data ◽  
E Region ◽  
Dip Equator ◽  
Ionospheric Electric Field ◽  
Coherent Radar

Abstract. We analyze the effects of the 2-day wave activity in the EEJ using one coherent scatter radar and eight magnetometer stations located close to the dip equator. The wavelet analysis of the magnetometer data reveals a 2-day signature in the semidiurnal geomagnetic tide. The E-region zonal background ionospheric electric field, derived from coherent radar measurements, shows 2-day oscillations in agreement with such oscillations in the magnetometers data. An anticorrelation between the amplitude of the tidal periodicites (diurnal and semidiurnal) and that of the 2-day signature is also shown in the electric fields. The results are compared with simultaneous observations of 2-day planetary wave in meridional winds and ionosonde data. Further, our results are discussed based on the analysis of the magnetic activity.

scholarly journals Equatorial E Region Electric Fields and Sporadic E Layer Responses to the Recovery Phase of the November 2004 Geomagnetic Storm

2017 ◽  
Vol 122 (12) ◽  
pp. 12,517-12,533 ◽  
Author(s):  
J. Moro ◽  
L. C. A. Resende ◽  
C. M. Denardini ◽  
J. Xu ◽  
I. S. Batista ◽  
...  
Keyword(s):  
Geomagnetic Storm ◽  
Electric Fields ◽  
Recovery Phase ◽  
E Region ◽  
Sporadic E Layer ◽  
Sporadic E

scholarly journals Effects of solar eclipse on the electrodynamical processes of the equatorial ionosphere: a case study during 11 August 1999 dusk time total solar eclipse over India

2002 ◽  
Vol 20 (12) ◽  
pp. 1977-1985 ◽  
Author(s):  
R. Sridharan ◽  
C. V. Devasia ◽  
N. Jyoti ◽  
Diwakar Tiwari ◽  
K. S. Viswanathan ◽  
...  
Keyword(s):  
Electric Fields ◽  
Solar Eclipse ◽  
Equatorial Ionosphere ◽  
Hf Radar ◽  
F Region ◽  
Large Enhancement ◽  
Temporal Structures ◽  
E Region ◽  
Field Lines ◽  
Electric Fields And Currents

Abstract. The effects on the electrodynamics of the equatorial E- and F-regions of the ionosphere, due to the occurrence of the solar eclipse during sunset hours on 11 August 1999, were investigated in a unique observational campaign involving ground based ionosondes, VHF and HF radars from the equatorial location of Trivandrum (8.5° N; 77° E; dip lat. 0.5° N), India. The study revealed the nature of changes brought about by the eclipse in the evening time E- and F-regions in terms of (i) the sudden intensification of a weak blanketing ES-layer and the associated large enhancement of the VHF backscattered returns, (ii) significant increase in h' F immediately following the eclipse and (iii) distinctly different spatial and temporal structures in the spread-F irregularity drift velocities as observed by the HF radar. The significantly large enhancement of the backscattered returns from the E-region coincident with the onset of the eclipse is attributed to the generation of steep electron density gradients associated with the blanketing ES , possibly triggered by the eclipse phenomena. The increase in F-region base height immediately after the eclipse is explained as due to the reduction in the conductivity of the conjugate E-region in the path of totality connected to the F-region over the equator along the magnetic field lines, and this, with the peculiar local and regional conditions, seems to have reduced the E-region loading of the F-region dynamo, resulting in a larger post sunset F-region height (h' F) rise. These aspects of E-and F-region behaviour on the eclipse day are discussed in relation to those observed on the control day.Key words. Ionosphere (electric fields and currents; equatorial ionosphere; ionospheric irregularities)

scholarly journals Simulations of the neutral structure within the dusk side aurora

2006 ◽  
Vol 24 (10) ◽  
pp. 2519-2532
Author(s):  
H. F. Parish ◽  
L. R. Lyons
Keyword(s):  
Electric Fields ◽  
Three Dimensional ◽  
Meridional Wind ◽  
Recovery Phase ◽  
Limited Area ◽  
Neutral Winds ◽  
E Region ◽  
Linear Interactions ◽  
Simulated Wind ◽  
Equivalent Conditions

Abstract. Observations of neutral winds from rocket release experiments within the premidnight and postmidnight substorm recovery phase aurora, show very large E-region neutral winds of several hundred m/s, where winds measured on the dusk side are even larger than those on the dawn side. These large winds are also associated with strong shears, and there is evidence that some of the regions below these shears may be unstable. The mechanisms which generate this strong vertical structure are not well understood. It is also not known whether the acceleration conditions in the pre and post midnight sectors of the aurora may produce significantly different neutral responses on the dawn and dusk sides. Simulations have been performed using a three-dimensional high resolution limited area thermosphere model to try to understand the neutral structure within the dawn and dusk side aurora. When simulations are performed using auroral forcing alone, for equivalent conditions within the dawn and dusk sectors, differences are found in the simulated response on each side. When measured values of auroral forcing parameters, and background winds and tides consistent with recent observations, are used as model inputs, some of the main features of the zonal and meridional wind observations are reproduced in the simulations, but the magnitude of the peak zonal wind around 140 km tends to be too small and the maximum meridional wind around 130 km is overestimated. The winds above 120 km altitude are found to be sensitive to changes in electric fields and ion densities, as was the case for the dawn side, but the effects of background winds and tides on the magnitudes of the winds above 120 km are found to be relatively small on the dusk side. The structure below 120 km appears to be related mainly to background winds and tides rather than auroral forcing, as was found in earlier studies on the dawn side, although the peak magnitudes of simulated wind variations in the 100 to 120 km altitude range are smaller than those observed. The source of the strong shears measured around 110 km altitude on the dusk side is uncertain, but may be related to different kinds of oscillations, such as gravity waves, non migrating semidiurnal tides, or secondary oscillations produced by non linear interactions between waves.

scholarly journals Cosmic radio noise absorption events associated with equatorward drifting arcs during a substorm growth phase

2004 ◽  
Vol 22 (5) ◽  
pp. 1675-1686 ◽  
Author(s):  
J. R. T. Jussila ◽  
A. T. Aikio ◽  
S. Shalimov ◽  
S. R. Marple
Keyword(s):  
Electron Temperature ◽  
Electric Fields ◽  
Growth Phase ◽  
Energetic Electron ◽  
Cosmic Radio ◽  
Radio Noise ◽  
Particle Precipitation ◽  
Noise Absorption ◽  
D Region ◽  
E Region

Abstract. Cosmic radio noise absorption (CNA) events associated with equatorward drifting arcs during a substorm growth phase are studied by using simultaneous optical auroral, IRIS imaging riometer and EISCAT incoherent scatter radar measurements. The CNA is generally attributed to energetic particle precipitation in the D-region. However, it has been argued that plasma irregularities or enhanced electron temperature (Te) in the E-region could also produce CNA. Both of the latter mechanisms are related to intense electric fields in the ionosphere. We present two events which occur during a substorm growth phase in the evening MLT sector. In both of the events, an auroral arc is drifting equatorward, together with a region of CNA (auroral absorption bay) located on the equatorward side and outside of the arc. Both of the events are associated with enhanced D-region electron density on the equatorward side of the auroral arc, but in the second event, a region of intense electric field and enhanced electron temperature in the E-region is also located on the equatorward side of the arc. We show that in the studied events neither plasma instabilities nor enhanced Te play a significant role in producing the measured CNA, but the CNA in the vicinity of the equatorward drifting arcs is produced by D-region energetic electron precipitation. Key words. Ionosphere (auroral ionosphere; particle precipitation; electric fields and currents)

Penetration of polar electric fields to the nightside dip equator at times of geomagnetic sudden commencements

1993 ◽  
Vol 98 (A10) ◽  
pp. 17517 ◽  
Author(s):  
J. Hanumath Sastri ◽  
J. V. S. Visweswara Rao ◽  
K. B. Ramesh
Keyword(s):  
Electric Fields ◽  
Sudden Commencements ◽  
Dip Equator

scholarly journals Comparison of E-region electric fields observed with a sounding rocket and a Doppler radar in the Seek Campaign

1998 ◽  
Vol 25 (11) ◽  
pp. 1773-1776 ◽  
Author(s):  
Mamoru Yamamoto ◽  
Tetsuya Itsuki ◽  
Takeshi Kishimoto ◽  
Roland T. Tsunoda ◽  
Robert F. Pfaff ◽  
...  
Keyword(s):  
Electric Fields ◽  
Doppler Radar ◽  
Sounding Rocket ◽  
E Region
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