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  

A Simulation of Equatorial Plasma Bubble Signatures on the 016300 Å nightglow Meridional Profile Over Brazilian Low Latitude

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Y. Nakamura ◽  
I.H.A. Sobral ◽  
M.A. Abdu
Keyword(s):  
Plasma Bubble ◽  
Low Latitude ◽  
Equatorial Plasma Bubble ◽  
Meridional Profile

Para solicitação de resumo, entrar em contato com editor-chefe ([email protected]). 

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 Comparison of equatorial plasma bubble zonal drifts and neutral winds velocity over Southeast Asia

2019 ◽  
Vol 1152 ◽  
pp. 012014
Author(s):  
Idahwati Sarudin ◽  
Nurul Shazana Abdul Hamid ◽  
Mardina Abdullah ◽  
Suhaila M Buhari
Keyword(s):  
Southeast Asia ◽  
Plasma Bubble ◽  
Neutral Winds ◽  
Equatorial Plasma Bubble

scholarly journals Observations of day-to-day variability in precursor signatures to equatorial F-region plasma depletions

1999 ◽  
Vol 17 (8) ◽  
pp. 1053-1063 ◽  
Author(s):  
P. R. Fagundes ◽  
Y. Sahai ◽  
I. S. Batista ◽  
M. A. Abdu ◽  
J. A. Bittencourt ◽  
...  
Keyword(s):  
Large Scale ◽  
Imaging System ◽  
Diagnostic Techniques ◽  
Field Of View ◽  
Atmospheric Composition ◽  
Plasma Bubble ◽  
Plasma Bubbles ◽  
F Region ◽  
Good Sequence ◽  
Region Plasma

Abstract. In December 1995, a campaign was carried out to study the day-to-day variability in precursor signatures to large-scale ionospheric F-region plasma irregularities, using optical diagnostic techniques, near the magnetic equator in the Brazilian sector. Three instruments were operated simultaneously: (a) an all-sky (180° field of view) imaging system for observing the OI 630 nm nightglow emission at Alcântara (2.5°S, 44.4°W); (b) a digisonde (256-Lowell) at São Luis (2.6°S, 44.2°W); and (c) a multi-channel tilting filter-type zenith photometer for observing the OI 630 nm and mesospheric nightglow emissions at Fortaleza (3.9°S, 38.4°W). During the period December 14-18, 1995 (summer in the southern hemisphere), a good sequence of the OI 630 nm imaging observations on five consecutive nights were obtained, which are presented and discussed in this study. The observing period was geomagnetically quiet to moderate  (Kp = 0+ to 5+; Dst = 18 nT to -37 nT). On four nights, out of the five observation nights, the OI 630 nm imaging pictures showed formations of transequatorial north-south aligned intensity depletions, which are the optical signatures of large-scale ionospheric F-region plasma bubbles. However, considerable day-to-day variability in the onset and development of the plasma depleted bands was observed. On one of the nights it appears that the rapid uplifting of the F-layer in the post-sunset period, in conjunction with gravity wave activity at mesospheric heights, resulted in generation of very strong plasma bubble irregularities. One of the nights showed an unusual formation of north-south depleted band in the western sector of the imaging system field of view, but the structure did not show any eastward movement, which is a normal characteristic of plasma bubbles. This type of irregularity structure, which probably can be observed only by wide-angle imaging system, needs more investigations for a better understanding of its behaviour.Key words. Atmospheric composition and structure (airglow and aurora) · Ionosphere (equatorial ionosphere; ionospheric irregularities)

scholarly journals Ionospheric and thermospheric response to the 27–28 February 2014 geomagnetic storm

2018 ◽  
Author(s):  
Khalifa Malki ◽  
Aziza Bounhir ◽  
Zouhair Benkhaldoun ◽  
Jonathan J. Makela ◽  
Nicole Vilmer ◽  
...  
Keyword(s):  
Geomagnetic Storm ◽  
Imaging System ◽  
Propagation Speed ◽  
Circulation Pattern ◽  
Plasma Bubble ◽  
Storm Activity ◽  
Seasonal Behavior ◽  
Neutral Winds ◽  
Atmospheric Disturbances ◽  
Mass Ejection

Abstract. The present work explores the ionospheric and thermospheric responses to the 27–28 February 2014 geomagnetic storm. For the first time, a geomagnetic storm is explored in north Africa using interferometer, all-sky imager and GPS data. This storm was caused by coronal mass ejection (CME) associated flares that occurred on 25 February 2014. A Fabry-Perot interferometer located at the Oukaimeden Observatory (31.206° N, 7.866° W, 22.84° N magnetic) in Morocco provides measurements of the thermospheric neutral winds based on the observations of the 630 nm redline emission. A wide angle imaging system records images of the 630-nm emission. The effects of this geomagnetic storm on the thermosphere are evident from the clear departure of the neutral winds from their seasonal behavior. During the storm, the winds experience an intense and steep equatorward flow from 21 to 01 LT and a westward flow from 22 to 03 LT. The equatorial wind speed reaches a maximum of 120 m/s for the meridional component at 22 LT, when the zonal wind reverses to the westward direction. Shortly after 00 LT a maximum westward speed of 80 m/s was achieved for the zonal component of the wind. The features of the winds are typical of TAD (Traveling Atmospheric Disturbances) induced circulation; the first TAD coming from the northern hemisphere reaches the site at 21 LT and a second one coming from the southern hemisphere reaches the site at about 00 LT. We estimate the propagation speed of the northern TAD to be 550 m/s. We compared the winds to DWM07 (Disturbance Wind Model) prediction model and find that this model gives a good indication of the new circulation pattern caused by storm activity, but deviates largely inside the TADs. The effects on the ionosphere were also evident through the change observed in the background electrodynamics from the reversal in drift direction in an observed equatorial plasma bubble. TEC measurements of a GPS station installed in Morocco, at Rabat (33.998° N; 6.853° W, geographic) revealed a positive storm.

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 Comparative investigations of equatorial electrodynamics and low-to-mid latitude coupling of the thermosphere-ionosphere system

2006 ◽  
Vol 24 (2) ◽  
pp. 503-513 ◽  
Author(s):  
M. J. Colerico ◽  
M. Mendillo ◽  
C. G. Fesen ◽  
J. Meriwether
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Circulation Model ◽  
Upper Atmosphere ◽  
Low Latitude ◽  
Brightness Wave ◽  
F Region ◽  
Fabry Perot ◽  
Low Latitudes ◽  
First Time

Abstract. The thermospheric midnight temperature maximum (MTM) is a highly variable, but persistent, large scale neutral temperature enhancement which occurs at low latitudes. Its occurrence can impact many fundamental upper atmospheric parameters such as pressure, density, neutral winds, neutral density, and F-region plasma. Although the MTM has been the focus of several investigations employing various instrumentation including photometers, satellites, and Fabry-Perot interferometers, limited knowledge exists regarding the latitude extent of its influence on the upper atmosphere. This is largely due to observational limitations which confined the collective geographic range to latitudes within ±23°. This paper investigates the MTM's latitudinal extent through all-sky imaging observations of its 6300Å airglow signature referred to by Colerico et al. (1996) as the midnight brightness wave (MBW). The combined field of view of three Southern Hemisphere imaging systems located at Arequipa, Peru, and Tucuman and El Leoncito, Argentina, for the first time extends the contiguous latitudinal range of imager observations to 8° S-39° S in the American sector. Our results highlight the propagation of MBW events through the combined fields of view past 39° S latitude, providing the first evidence that the MTM's effect on the upper atmosphere extends into mid-latitudes. The observations presented here are compared with modeled 6300Å emissions calculated using the NCAR thermosphere-ionosphere-electrodynamic general circulation model (TIEGCM) in conjunction with an airglow code. We report that at this time TIEGCM is unable to simulate an MBW event due to the model's inability to reproduce an MTM of the same magnitude and occurrence time as those observed via FPI measurements made from Arequipa. This work also investigates the origins of an additional low latitude airglow feature referred to by Colerico et al. (1996) as the pre-midnight brightness wave (PMBW) and described as an enhancement in 6300Å emission which occurs typically between 20:00-22:00 LT and exhibits equatorward propagation. We present the first successful simulation of a PMBW event using the TIEGCM and the airglow code. We find that the PMBW's origin is electro-dynamical in nature, resulting from the expected evening decay of the inter-tropical arcs.

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