scholarly journals The study of equatorial plasma bubble during January to April 2012 over Kolhapur (India)

2016 ◽  
Vol 59 (2) ◽  
Author(s):  
Parashram T. Patil ◽  
Rupesh N. Ghodpage ◽  
Alok K. Taori ◽  
Rohit P. Patil ◽  
Subramanian Gurubaran ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Emission Line ◽  
Drift Velocity ◽  
Velocity Variation ◽  
Plasma Bubble ◽  
Low Latitude ◽  
Plasma Bubbles ◽  
F Region ◽  
Equatorial Plasma Bubbles ◽  
Observation Period

<p>Over 53 nights of all sky airglow imager data collected during January-April 2012 from the low latitude station Kolhapur (16.68°N, 74.26°E; 10.6°N dip latitude) have been analyzed to study the F-region dynamics through the imaging of OI 630 nm emission line. The observed night airglow data were supported by the ionosonde measurements from Tirunelveli (8.7°N, 77.8°E; 0.51°N dip latitude). Well defined magnetic field aligned depletions were observed during the observation period. Out of 53 nights, 40 nights exhibited the occurrence of north-south aligned equatorial plasma bubbles. These plasma bubbles were found moving towards east with drift speed in range between 70 to 200 m s<span><sup>-1</sup></span>. We have analyzed the zonal drift velocity variation and relation of bubble occurrence with the base height of the ionosphere together with the effects of the geomagnetic Ap and solar flux F<span><sub>10.7</sub></span> cm index in its first appearance.</p>

scholarly journals Study of Equatorial Plasma Bubbles Using ASI and GPS Systems

2020 ◽  
Author(s):  
Dada P. Nade ◽  
Swapnil S. Potdar ◽  
Rani P. Pawar
Keyword(s):  
Electron Content ◽  
Gps Receiver ◽  
Plasma Bubble ◽  
Low Latitude ◽  
Total Electron ◽  
Plasma Irregularities ◽  
Plasma Bubbles ◽  
F Region ◽  
Equatorial Plasma Bubbles ◽  
Background Density

The plasma irregularities have been frequently observed in the F-region, at low latitude regions, due to the instability processes occurring in the ionosphere. The depletions in electron density, as compared to the background density, is a signature of the plasma irregularities. These irregularities are also known as the “equatorial plasma bubble” (EPB). These EPBs can measure by the total electron content (TEC) using GPS receiver and by images of the nightglow OI 630.0 nm emissions using all sky imager (ASI). The current chapter is based on the review on the signature of the EPBs in TEC and ASI. measurements. We have also discussed the importance of the study of EPBs.

scholarly journals Effect of magnetic activity on plasma bubbles over equatorial and low-latitude regions in East Asia

2009 ◽  
Vol 27 (1) ◽  
pp. 303-312 ◽  
Author(s):  
G. Li ◽  
B. Ning ◽  
L. Liu ◽  
W. Wan ◽  
J. Y. Liu
Keyword(s):  
East Asia ◽  
Electric Fields ◽  
Time Delays ◽  
Magnetic Activity ◽  
Weak Correlation ◽  
Plasma Bubble ◽  
Low Latitude ◽  
Gps Receivers ◽  
Plasma Bubbles ◽  
Equatorial Plasma Bubbles

Abstract. The dependence of plasma bubble occurrence in the eveningside ionosphere, with magnetic activity during the period years 2001–2004, is studied here based on the TEC observations gathered by ground-based GPS receivers which are located in the equatorial and low-latitude regions in East Asia. The observed plasma bubbles consist of the plasma-bubble events in the equatorial (stations GUAM, PIMO and KAYT), and low-latitude regions (stations WUHN, DAEJ and SHAO). It is shown that most equatorial plasma-bubble events commence at 20:00 LT, and may last for >60 min. The magnetic activity appears to suppress the generation of equatorial plasma bubbles with a time delay of more than 3 h (4–9 h). While in the low-latitude regions, most plasma-bubble events commence at about 23:00 LT and last for <45 min. The best correlation between Kp and low-latitude plasma-bubble occurrence is found with an 8–9 h delay, a weak correlation exists for time delays of 6–7 h. This probably indicates that over 3 h delayed disturbance dynamo electric fields obviously inhibit the development of plasma bubbles in the pre-midnight sector.

scholarly journals Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector

2019 ◽  
Author(s):  
Fabio Vargas ◽  
Christiano Brum ◽  
Pedrina Terra ◽  
Delano Gobbi
Keyword(s):  
Standard Deviation ◽  
Drift Velocity ◽  
Velocity Estimation ◽  
Plasma Bubble ◽  
The West ◽  
Equatorial Station ◽  
Plasma Bubbles ◽  
Latitude Station ◽  
The Mean

We present in this work a method for estimation of plasma bubble mean zonal drift velocities using keograms generated from images of the OI 6300.0 nm nightglow emission collected from an equatorial station -- Cariri (7.4$^\circ$S, 36.5$^\circ$W), and a mid-latitude station -- Cachoeira Paulista (22.7$^\circ$S, 45$^\circ$W), both in the Brazilian sector. The mean zonal drift velocities were estimated for 239 events recorded from 2000 to 2003 in Cariri, and for 56 events recorded over Cachoeira Paulista from 1998 to 2000. It was found that plasma bubble zonal drift velocities are smaller ($\sim$60 ms$^{-1}$) for events occurring later in the night compared to those occurring earlier ($\sim$150 ms$^{-1}$). The decreasing rate of the zonal drift velocity is of $\sim$10 ms$^{-1}$/h. We have also found that, in general, bubble events appearing first in the west-most region of the keogram are faster than those appearing first in the east-most region of the keograms. Larger zonal drift velocities occur from 19 LT to 23 LT in a longitude range from 37$^\circ$ to 33$^\circ$. The method of velocity estimation using keograms compares favorably against the mosaic method developed by \cite{Arruda:2005}, but the standard deviation of the residuals for the zonal drift velocities from the two methods is $\sim$15 ms$^{-1}$

scholarly journals Filamentary Alfvénic structures excited at the edges of equatorial plasma bubbles

2007 ◽  
Vol 25 (10) ◽  
pp. 2159-2165 ◽  
Author(s):  
R. Pottelette ◽  
M. Malingre ◽  
J. J. Berthelier ◽  
E. Seran ◽  
M. Parrot
Keyword(s):  
Alfven Waves ◽  
Alfvén Waves ◽  
Plasma Bubble ◽  
Plasma Bubbles ◽  
Wave Measurements ◽  
Demeter Satellite ◽  
Equatorial Plasma Bubbles ◽  
Background Magnetic Field ◽  
Gravity Driven ◽  
Displacement Currents

Abstract. Recent observations performed by the French DEMETER satellite at altitudes of about 710 km suggest that the generation of equatorial plasma bubbles correlates with the presence of filamentary structures of field aligned currents carried by Alfvén waves. These localized structures are located at the bubble edges. We study the dynamics of the equatorial plasma bubbles, taking into account that their motion is dictated by gravity driven and displacement currents. Ion-polarization currents appear to be crucial for the accurate description of the evolution of plasma bubbles in the high altitude ionosphere. During their eastward/westward motion the bubbles intersect gravity driven currents flowing transversely with respect to the background magnetic field. The circulation of these currents is prohibited by large density depressions located at the bubble edges acting as perfect insulators. As a result, in these localized regions the transverse currents have to be locally closed by field aligned currents. Such a physical process generates kinetic Alfvén waves which appear to be stationary in the plasma bubble reference frame. Using a two-dimensional model and "in situ" wave measurements on board the DEMETER spacecraft, we give estimates for the magnitude of the field aligned currents and the associated Alfvén fields.

First Zonal Drift Velocity Measurement of Equatorial Plasma Bubbles (EPBs) From a Geostationary Orbit Using GOLD Data

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
Deepak K. Karan ◽  
Robert E. Daniell ◽  
Scott L. England ◽  
Carlos R. Martinis ◽  
Richard W. Eastes ◽  
...  
Keyword(s):  
Drift Velocity ◽  
Velocity Measurement ◽  
Geostationary Orbit ◽  
Plasma Bubbles ◽  
Equatorial Plasma Bubbles

scholarly journals Simultaneous observations of equatorial F-region plasma depletions over Brazil during the Spread-F Experiment (SpreadFEx)

2009 ◽  
Vol 27 (6) ◽  
pp. 2371-2381 ◽  
Author(s):  
P.-D. Pautet ◽  
M. J. Taylor ◽  
N. P. Chapagain ◽  
H. Takahashi ◽  
A. F. Medeiros ◽  
...  
Keyword(s):  
Gravity Wave ◽  
State University ◽  
Large Area ◽  
Plasma Bubbles ◽  
F Region ◽  
Equatorial Plasma Bubbles ◽  
Star Program ◽  
Spread F ◽  
Plasma Depletions ◽  
Bubble Characteristics

Abstract. From September to November 2005, the NASA Living with a Star program supported the Spread-F Experiment campaign (SpreadFEx) in Brazil to study the effects of convectively generated gravity waves on the ionosphere and their role in seeding Rayleigh-Taylor instabilities, and associated equatorial plasma bubbles. Several US and Brazilian institutes deployed a broad range of instruments (all-sky imagers, digisondes, photometers, meteor/VHF radars, GPS receivers) covering a large area of Brazil. The campaign was divided in two observational phases centered on the September and October new moon periods. During these periods, an Utah State University (USU) all-sky CCD imager operated at São João d'Aliança (14.8° S, 47.6° W), near Brasilia, and a Brazilian all-sky CCD imager located at Cariri (7.4° S, 36° W), observed simultaneously the evolution of the ionospheric bubbles in the OI (630 nm) emission and the mesospheric gravity wave field. The two sites had approximately the same magnetic latitude (9–10° S) but were separated in longitude by ~1500 km. Plasma bubbles were observed on every clear night (17 from Brasilia and 19 from Cariri, with 8 coincident nights). These joint datasets provided important information for characterizing the ionospheric depletions during the campaign and to perform a novel longitudinal investigation of their variability. Measurements of the drift velocities at both sites are in good agreement with previous studies, however, the overlapping fields of view revealed significant differences in the occurrence and structure of the plasma bubbles, providing new evidence for localized generation. This paper summarizes the observed bubble characteristics important for related investigations of their seeding mechanisms associated with gravity wave activity.

scholarly journals Electrodynamics of the Low-latitude Thermosphere by Comparison of Zonal Neutral Winds and Equatorial Plasma Bubble Velocity

2015 ◽  
Vol 20 (2) ◽  
pp. 84-89 ◽  
Author(s):  
Narayan P. Chapagain
Keyword(s):  
Imaging System ◽  
Bubble Velocity ◽  
Plasma Bubble ◽  
Low Latitude ◽  
Neutral Winds ◽  
Coupling Relationship ◽  
F Region ◽  
Fabry Perot ◽  
Optical Imaging System ◽  
Equatorial Plasma Bubble

The coincident observations of nighttime thermospheric zonal neutral winds and equatorial plasma bubble (EPB) drift velocities over Brazil during the October–December,2009 and 2010 are used to examine the coupling relationship between the thermosphere and ionosphere. The EPB zonal drift velocities are estimated using the airglow images recorded by optical imaging system, while the neutral winds are measured by using a bi-static Fabry–Perot interferometer (FPI) experiment deployed at two stations from Brazil. The results reveal the similar pattern in the EPB drift velocities and zonal neutral winds motion during the nighttime and night-to-night thereby illustrating a fully developed F-region dynamo. However, background natural winds also exceed EPBs velocities especially during the development phase of EPBs illustrating that F-region dynamo is not fully activated.Journal of Institute of Science and Technology, 2015, 20(2): 84-89  

scholarly journals F-Region electron density irregularities during the development of equatorial plasma bubbles

2000 ◽  
Vol 39 (1) ◽  
pp. 117-125
Author(s):  
P. Muralikrishna
Keyword(s):  
Electron Density ◽  
Plasma Bubbles ◽  
Black Brant ◽  
F Region ◽  
Equatorial Plasma Bubbles ◽  
Electron Density Irregularities

Algunos resultados nuevos que se obtuvieron de mediciones in situ de la variación de la densidad electrónica hechas con sondas instaladas en cohetes para medir la densidad electrónica durante dos campañas que se llevaron a cabo en Alcántara (2.31° Sur 32.5° Oeste) se presentan aquí. Durante la primera campaña que se llevó a cabo en colaboración con la NASA (campaña de Iguará donde se lanzó el cohete Black Brant X el 14 de octubre de 1994) para investigar el fenómeno de los eventos de dispersión F que ocurren en altas altitudes en zonas ecuatoriales. Adicionalmente a algunos instrumentos de diagnóstico de plasma que fueron provistos por otros institutos participantes, la División de Acronomía del Instituto de Pesquisas Espaciales en Brasil, proporcionó una sonda de capacitancia de alta frecuencia que midió el perfil de alturas de la densidad electrónica. Durante la segunda campaña el cohete sonda 3 hecho en Brasil fue lanzado el 18 de diciembre de 1995. El cohete llevaba instrumentos para medir la densidad electrónica que determinaron el perfil de densidades electrónicas en la ionosfera. Algunos equipos fueron operados desde tierra para asegurarnos que los cohetes fueran lanzados en condiciones favorables para la generación de burbujas de plasma en la región F; los cohetes en ambas ocasiones atravesaron algunas burbujas de plasma en desarrollo. El espectro K de las irregularidades de plasma se obtuvo por análisis espectral de las fluctuaciones de la densidad electrónica. Las irregularidades en la densidad electrónica asociadas con las burbujas de plasma tienen líneas muy agudas en sus espectros K; estas líneas se extienden sobre un amplio rango de alturas. Lo que podría esperarse de las teorías existentes en la generación de irregularidades de pequeña escala por el proceso de cascada es un espectro K plano. Los resultados actuales podrían indicarnos la presencia de modos de onda preferidos en burbujas de plasma en desarrollo.

scholarly journals MODEL OF MID-AND LOW-LATITUDE F REGION IONOSPHERE AND PROTONOSPHERE

1981 ◽  
Vol 20 (1) ◽  
pp. 11-39
Author(s):  
A. Tan ◽  
S. T. Wu
Keyword(s):  
Drift Velocity ◽  
Loss Rate ◽  
Electron Content ◽  
Low Latitude ◽  
Ion Density ◽  
Total Electron ◽  
F Region ◽  
Latitude Station ◽  
Nocturnal Increase ◽  
Radio Beacon

The coupled continuity and momentum equations of O+ and H+ ions in the F region and the protonosphere are solved for a mid-latitude station (Arecibo) and a low-latitude station (Jicamarca) to investigate the diurnal behavior of the peak electron density NmF2, the height of the peak HmF2, the O+-H+ transition height Htr and the transition level ion density Ntr. The effects of the neutral wind on the NmF2, HmF2 Ntr and Htr curves above Arecibo are more important than and generally in the opposite direction of those of a sinusoidal elctromagnetic drift. the electromagnetic drift plays a fa-reaching role in shaping the ionospheric and protonospheric profiles at Jicamarca.  An upward drift that peaks during the day produces a 'valey' in the NmF2 curve, while an upward drift that stays constant during ost of the day produces a 'plateau'.  The nighttime decay in Nmf2 is due to the conbined effects of a slow downward drift and chemical recombination.  A nocturnal increase in NmF2 is due to a sufficiently large downward drift when the resultant 'squeezing' of the field tubes overcomes the O+ loss rate.  The diurnal variations of HmF2 and Htr tend to follow that of the upward drift velocity pattern, with gradients somewhat smoothed.  A downward reversal of the drift at sunset causes and enhancement in the post-sunset Ntr. Finally, the applicability of the model to the study of the total electron content measurements of the ATS-6 radio beacon experiments at Ootacamund is demonstrated.  By comparing with the observed values, the probable drift velocities over Ootacamund are determined for October and December, 1975.  The drift velocity patterns show broad similitarities with those observed over Jicamarca.

scholarly journals Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 69
Author(s):  
Fabio Vargas ◽  
Christiano Brum ◽  
Pedrina Terra ◽  
Delano Gobbi
Keyword(s):  
Standard Deviation ◽  
Drift Velocity ◽  
Zonal Wind ◽  
Velocity Estimation ◽  
Plasma Bubble ◽  
The West ◽  
Equatorial Station ◽  
Plasma Bubbles ◽  
The Mean ◽  
Vertical Gradients

We present in this work a method for estimation of equatorial plasma bubble (EPB) mean zonal drift velocities using keograms generated from images of the OI 6300.0 nm nightglow emission collected from an equatorial station–Cariri (7.4° S, 36.5° W), and a mid-latitude station–Cachoeira Paulista (22.7° S, 45° W), both in the Brazilian sector. The mean zonal drift velocities were estimated for 239 events recorded from 2000 to 2003 in Cariri, and for 56 events recorded over Cachoeira Paulista from 1998 to 2000. It was found that EPB zonal drift velocities are smaller (≈60 ms−1) for events occurring later in the night compared to those occurring earlier (≈150 ms−1). The decreasing rate of the zonal drift velocity is ≈10 ms−1/h. We have also found that, in general, bubble events appearing first in the west-most region of the keograms are faster than those appearing first in the east-most region. Larger zonal drift velocities occur from 19 to 23 LT in a longitude range from −37° to −33°, which shows that the keogram method can be used to describe vertical gradients in the thermospheric wind, assuming that the EPBs drift eastward with the zonal wind. The method of velocity estimation using keograms compares favorably against the mosaic method developed by Arruda, D.C.S, 2005, but the standard deviation of the residuals for the zonal drift velocities from the two methods is not small (≈15 ms−1).

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