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 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)

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 ◽  
Ricardo Arlen Buriti
Keyword(s):  
Equatorial Ionosphere ◽  
Plasma Drift ◽  
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)

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

CIR/HSSS-related TID activity and their interhemispheric circulation

2020 ◽  
Author(s):  
Dalia Buresova ◽  
John Bosco Habarulema ◽  
Jurgen Watermann ◽  
Ilya K. Edemskiy ◽  
Jaroslav Urbar ◽  
...  
Keyword(s):  
Quantitative Information ◽  
Magnetic Storms ◽  
Detection Methods ◽  
Gps Receiver ◽  
Plasma Bubbles ◽  
Plasma Drift ◽  
Space And Time ◽  
Ionospheric Variability ◽  
F Region ◽  
Gnss Receivers

&lt;p&gt;The paper presents results of the analysis of the changes in the regular ionospheric variability and TID activity observed during CIR/HSSS-related storms. We analyzed main ionospheric parameters retrieved from manually scaled ionograms, plasma drift measurements and TEC data obtained from several European and African ionospheric stations and GNSS receivers. Most of the observed storm-related TIDs had periods of 60-180 min (LSTIDs). During the analyzed storms we also observed extraordinary spreads and plasma bubbles at the F region heights. The results of the analysis were compared with the TID activity during strong magnetic storms of CME origin along the European-African sector. In order to obtain quantitative information on the likeliness and morphology of interhemispheric circulation of LSTIDs at about 40 events were examined lasting between 8 and 24 hours each. We used exclusively GPS-based detection methods, specifically information on TEC, TEC deviations in space and time from a background reference (dTEC), and the Rate of TEC change in time (ROT), all inferred from GPS receiver networks in Europe and Africa. We conclude that hemispheric conjugacy of LSTID is highly probable while interhemispheric circulation rather unlikely but still occurring during some periods.&lt;/p&gt;

scholarly journals On developing a new ionospheric plasma index for Brazilian equatorial F region irregularities

2019 ◽  
Vol 37 (5) ◽  
pp. 807-818 ◽  
Author(s):  
Laysa Cristina Araujo Resende ◽  
Clezio Marcos Denardini ◽  
Giorgio Arlan Silva Picanço ◽  
Juliano Moro ◽  
Diego Barros ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Space Weather ◽  
Ionospheric Plasma ◽  
Monitoring Program ◽  
Plasma Irregularities ◽  
Plasma Drift ◽  
F Region ◽  
Maximum Value ◽  
Spread F

Abstract. F region vertical drifts (Vz) are the result of the interaction between ionospheric plasma with the zonal electric field and the Earth's magnetic field. Abrupt variations in Vz are strongly associated with the occurrence of plasma irregularities (spread F) during the nighttime periods. These irregularities are manifestations of space weather in the ionosphere's environment without necessarily requiring a solar burst. In this context, the Brazilian Space Weather Study and Monitoring Program (Embrace) of the National Institute for Space Research (INPE) has been developing different indexes to analyze these ionospheric irregularities in the Brazilian sector. Therefore, the main purpose of this work is to produce a new ionospheric scale based on the analysis of the ionospheric plasma drift velocity, named AV. It is based on the maximum value of Vz (Vzp), which in turn is calculated through its relationship with the virtual height parameter, h′F, measured by the Digisonde Portable Sounder (DPS-4D) installed in São Luís (2∘ S, 44∘ W; dip: −2.3∘). This index quantifies the time relationship between the Vz peak and the irregularity observed in the ionograms. Thus, in this study, we analyzed 7 years of data, between 2009 and 2015, divided by season in order to construct a standardized scale. The results show there is a delay of at least 15 min between the Vzp observation and the irregularity occurrence. Finally, we believe that this proposed index allows for evaluating the impacts of ionospheric phenomena in the space weather environment.

scholarly journals Impact of disturbance electric fields in the evening on prereversal vertical drift and spread F developments in the equatorial ionosphere

2018 ◽  
Vol 36 (2) ◽  
pp. 609-620 ◽  
Author(s):  
Mangalathayil A. Abdu ◽  
Paulo A. B. Nogueira ◽  
Angela M. Santos ◽  
Jonas R. de Souza ◽  
Inez S. Batista ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Plasma Bubble ◽  
Large Variability ◽  
Plasma Drift ◽  
F Region ◽  
Vertical Drift ◽  
Spread F ◽  
The Impact ◽  
Magnetic Disturbances

Abstract. Equatorial plasma bubble/spread F irregularity occurrence can present large variability depending upon the intensity of the evening prereversal enhancement in the zonal electric field (PRE), that is, the F region vertical plasma drift, which basically drives the post-sunset irregularity development. Forcing from magnetospheric disturbances is an important source of modification and variability in the PRE vertical drift and of the associated bubble development. Although the roles of magnetospheric disturbance time penetration electric fields in the bubble irregularity development have been studied in the literature, many details regarding the nature of the interaction between the penetration electric fields and the PRE vertical drift still lack our understanding. In this paper we have analyzed data on F layer heights and vertical drifts obtained from digisondes operated in Brazil to investigate the connection between magnetic disturbances occurring during and preceding sunset and the consequent variabilities in the PRE vertical drift and associated equatorial spread F (ESF) development. The impact of the prompt penetration under-shielding eastward electric field and that of the over-shielding, and disturbance dynamo, westward electric field on the evolution of the evening PRE vertical drift and thereby on the ESF development are briefly examined. Keywords. Ionosphere (ionospheric irregularities)

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