Estimating the daytime vertical E × B drift velocities in the F-region of the equatorial ionosphere using the IEEY and AMBER magnetic data in West Africa

2020 ◽  
Vol 65 (11) ◽  
pp. 2573-2585
Author(s):  
A.A. Kassamba ◽  
V. Doumbia ◽  
O.K. Obrou ◽  
F.O. Grodji ◽  
Z. Tuo ◽  
...  
Keyword(s):  
West Africa ◽  
Equatorial Ionosphere ◽  
Magnetic Data ◽  
F Region

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)

F-region nocturnal zonal plasma drift velocities of the brazilian equatorial ionosphere during maximum solar

2005 ◽  
Author(s):  
Daniela Cristina Santana Arruda ◽  
José Humberto Andrade Sobral ◽  
Mangalathayil Ali Abdu ◽  
Vivian Moreira de Castilho and Ricardo Arlen Buriti
Keyword(s):  
Equatorial Ionosphere ◽  
Plasma Drift ◽  
F Region

scholarly journals Morphological aspects of a new type of counter electrojet event

1999 ◽  
Vol 17 (2) ◽  
pp. 210-219 ◽  
Author(s):  
R. G. Rastogi
Keyword(s):  
Electric Fields ◽  
Current System ◽  
Equatorial Ionosphere ◽  
Geomagnetic Disturbances ◽  
Counter Electrojet ◽  
F Region ◽  
New Type ◽  
Northern Winter ◽  
Sporadic E ◽  
Electric Fields And Currents

Abstract. The study describes the time and space morphologies of a rather new type of counter electrojet event on the basis of data from the excellent chain of magnetic and ionospheric observatories along the Indo-Russian longitude sector. Abnormally large westward currents are observed during almost the whole of the daytime hours on a series of days. These events do not form any vortices in the current system and do not apparently seem to be associated with tidal effects or any solar magnetosphere events or geomagnetic disturbances. The existence of a westward electric field over the equatorial ionosphere has been confirmed by the absence of an equatorial type of sporadic E in the ionograms at Thumba precisely during the periods when ∆H at Trivandrum minus ∆H at Alibag is negative. The equatorial F region anomaly was also absent on the counter electrojet day. Such counter electrojet events during the northern winter months of low solar activity years are suggested to be the result of the modified wind system in the ionosphere associated with stratospheric warming events.Key words. Geomagnetism and paleomagnetism (time variations · diurnal to secular) · Ionosphere (electric fields and currents; equatorial ionosphere)

scholarly journals Estimating some parameters of the equatorial ionosphere electrodynamics from ionosonde data in West Africa

2017 ◽  
Vol 59 (1) ◽  
pp. 311-325 ◽  
Author(s):  
F.O. Grodji ◽  
V. Doumbia ◽  
K. Boka ◽  
C. Amory-Mazaudier ◽  
Y. Cohen ◽  
...  
Keyword(s):  
West Africa ◽  
Equatorial Ionosphere

Height gradient of F region vertical drift in the evening equatorial ionosphere

1995 ◽  
Vol 22 (19) ◽  
pp. 2645-2648 ◽  
Author(s):  
J. Hanumath Sastri ◽  
V. K. Meena Varma ◽  
S. R. Prabhakaran Nayar
Keyword(s):  
Equatorial Ionosphere ◽  
F Region ◽  
Vertical Drift

scholarly journals Letter to the editor: Electric field fluctuations (25-35 min) in the midnight dip equatorial ionosphere

2000 ◽  
Vol 18 (2) ◽  
pp. 252-256 ◽  
Author(s):  
J. Hanumath Sastri ◽  
H. Luhr ◽  
H. Tachihara ◽  
T. -I. Kitamura ◽  
J. V. S. V. Rao
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Geomagnetic Latitude ◽  
Equatorial Ionosphere ◽  
Plasma Drift ◽  
F Region ◽  
Vertical Drift ◽  
Field Fluctuations ◽  
Dip Equator ◽  
Electric Fields And Currents

Abstract. Measurements with a HF Doppler sounder at Kodaikanal (10.2°N, 77.5°E, geomagnetic latitude 0.8°N) showed conspicuous quasi-periodic fluctuations (period 25-35 min) in F region vertical plasma drift, Vz in the interval 0047-0210 IST on the night of 23/24 December, 1991 (Ap = 14, Kp < 4-). The fluctuations in F region vertical drift are found to be coherent with variations in Bz (north-south) component of interplanetary magnetic field (IMF), in geomagnetic H/X components at high-mid latitude locations both in the sunlit and dark hemispheres and near the dayside dip equator, suggestive of DP2 origin. But the polarity of the electric field fluctuations at the midnight dip equator (eastward) is the same as the dayside equator inferred from magnetic variations, contrary to what is expected of equatorial DP2. The origin of the coherent occurrence of equatorial electric field fluctuations in the DP2 range of the same sign in the day and night hemispheres is unclear and merits further investigations.Key words: Ionosphere (electric fields and currents; equatorial ionosphere; ionosphere-magnetosphere interactions)

On: “An Aeromagnetic and Aero‐radioactivity Survey of Liberia, West Africa,” by John C. Behrendt and Cletus S. Wotorson (GEOPHYSICS June 1971, p. 590–604)

Geophysics ◽  
1972 ◽  
Vol 37 (4) ◽  
pp. 701-701
Author(s):  
R. Jerry Brod
Keyword(s):  
West Africa ◽  
Magnetic Data ◽  
Magnetic Survey ◽  
Final Choice ◽  
Radiation Data ◽  
Factors Influencing

Perhaps the most significant criticism of this paper is that it does not establish the priorities that determined the equipment used and the manner in which the radiation and magnetic data were to be collected. According to Dr. Behrendt, considerations for the magnetic survey were dominant and the radiation capability was added as a subordinate system. The desirability of using a system with spectral capability was recognized, but cost considerations dictated the final choice. Operationally, the prime consideration was for the factors influencing the collection of magnetic data so that radiation data were sometimes collected at less than ideal times.

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