Measurements of equatorial plasma depletion velocity using 630 nm airglow imaging over a low‐latitude Indian station

Taori, A.; Sindhya, A.

doi:10.1002/2013ja019465

Cited by 23 publications

(24 citation statements)

References 37 publications

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“…Using airglow imager observations from Sriharikota, a location ~100 km east of Gadanki, Sinha and Raizada [] estimated eastward drifts, which varied from 190 m s −1 at ~21 LT to 40 m s −1 at 01 LT. Tiwari et al . [], using VHF scintillation observations from Tirunelveli, an equatorial location, found zonal drifts to vary from 200 m s −1 at ~20 LT to 50 m s −1 at 01 LT. More recently, using airglow imager observations from Gadanki, Taori and Sindhya [] estimated eastward drift of plasma depletions to be 120–175 m s −1 . It may be mentioned that eastward drifts derived using airglow imager observations correspond to an altitude of ~250 km.…”

Section: Resultsmentioning

confidence: 99%

“…Eastward drifts varied from one night to other and are found to be in the range of 90-210 m s À1 . recently, using airglow imager observations from Gadanki, Taori and Sindhya [2014] estimated eastward drift of plasma depletions to be 120-175 m s À1 . It may be mentioned that eastward drifts derived using airglow imager observations correspond to an altitude of~250 km.…”

Section: Figures 13amentioning

confidence: 99%

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First results on low‐latitude E and F region irregularities obtained using the Gadanki Ionospheric Radar Interferometer

et al. 2014

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A 30 MHz radar has recently been established at Gadanki (13.5°N, 79.2°E; 6.5°N magnetic latitude) to make unattended observations of the ionospheric field-aligned irregularities (FAI). This radar, called the Gadanki Ionospheric Radar Interferometer (GIRI), has been designed to have scanning capability of 100°in the east-west plane perpendicular to Earth's magnetic field and interferometry/imaging system to study drifts and spatial distribution of plasma irregularities at both large and small scales. In this paper, we present the first results on the E and F region FAI made using the scanning capability of the GIRI. Daytime observations of E region FAI show type 2 echoes with velocities predominantly upward northward (downward-southward) at altitudes >100 km (<100 km) and westward (eastward) in the forenoon (afternoon) with signature of tidal wind field. F region irregularities show bottom-type, bottomside and plume structures with close resemblance to those observed over the magnetic equator. Observations made with the east-west scanning capability have been used to study the origin, evolution, and drift of the FAI for the first time from Gadanki. Eastward drifts are estimated to be 90-210 m s À1 during 20-24 LT. Upward velocity as large as 500 m s À1 has been observed in the initial phase of the plume structures. Intriguingly, downward velocity as large as 60 m s À1 has also been observed in the plumes, displaying descending pattern, observed in the early evening hours. These results are presented and discussed in the light of current understanding of low-latitude plasma irregularities, and future prospects of GIRI are outlined.

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Section: Resultsmentioning

confidence: 99%

Section: Figures 13amentioning

confidence: 99%

First results on low‐latitude E and F region irregularities obtained using the Gadanki Ionospheric Radar Interferometer

et al. 2014

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“…EPBs are frequently observed over Indian region using all-sky imaging observations [Sinha and Raizada, 2000;Mukherjee, 2003;Rajesh et al, 2010;Narayanan et al, 2012;Nade et al, 2013Nade et al, , 2015Sharma et al, 2014;Taori and Sindhya, 2014]. We utilize all-sky imaging of OI 630 nm emission obtained from Indian station Panhala (16.8°N, 74.1°E geographic, 11.1°N dip latitude) in campaign mode observations during January to March 2008.…”

Section: Databasementioning

confidence: 99%

Shrinking equatorial plasma bubbles

et al. 2016

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The formation of equatorial plasma bubbles (EPBs) associated with spread F irregularities are fairly common phenomenon in the postsunset equatorial ionosphere. These bubbles grow as a result of eastward polarization electric field resulting in upward E × B drift over the dip equator. As they grow they are also mapped to low latitudes along magnetic field lines. The EPBs are often observed as airglow depletions in the images of OI 630 nm emission. On occasions the growth of the features over the dip equator is observed as poleward extensions of the depletions in all‐sky images obtained from low latitudes. Herein, we present interesting observations of decrease in the latitudinal extent of the EPBs corresponding to a reduction in their apex altitudes over the dip equator. Such observations indicate that these bubbles not only grow but also shrink on occasions. These are the first observations of shrinking EPBs. The observations discussed in this work are based on all‐sky airglow imaging observations of OI 630.0 nm emission made from Panhala (11.1°N dip latitude). In addition, ionosonde observations made from dip equatorial site Tirunelveli (1.1°N dip latitude) are used to understand the phenomenon better. The analysis indicates that the speed of shrinking occurring in the topside is different from the bottomside vertical drifts. When the EPBs shrink, they might decay before sunrise hours.

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“…The different aspects of EPBs have been studied by many researchers such as occurrence characteristics (e.g., Candido et al, 2011;Makela et al, 2004;Sahai et al, 1994;Sharma et al, 2014;Sun et al, 2016), morphology and evolution (e.g., Aggson et al, 1996;Huba et al, 2015;Wu et al, 2017), statistical features of EPBs (e.g., Narayanan et al, 2017;Sinha & Raizada, 2000;Sun et al, 2016), and zonal drift velocity (e.g., Abalde et al, 2004;Immel et al, 2004;Mukherjee & Shetti, 2008;Nade et al, 2013;Paulino et al, 2011;Pimenta et al, 2001;Taori et al, 2013;Yao & Makela, 2007). However, there are different techniques to monitor and study the evolution and characteristics of these large-scale structures (EPBs) such as incoherent scatter radar (e.g., Fejer et al, 1991), VHF spaced receiver system (e.g., Bhattacharyya et al, 2003;Sharma et al, 2018), Fabry-Pérot interferometer (e.g., Sahai et al, 1992), GPS (e.g., Haase et al, 2011;Ji et al, 2011;Nade et al, 2015), and ASI (e.g., Fagundes et al, 1997;Ghodpage et al, 2018;Kishore & Mukherjee, 2007;Nade et al, 2013;Sobral et al, 2009;Taori & Sindhya, 2014). Sun et al (2016) investigated the statistical features of EPBs using airglow images from 2012 to 2014, which lies in the increasing phase of 24th solar cycle from a ground-based network of four ASIs in the equatorial region of China.…”

Section: Introductionmentioning

confidence: 99%

Zonal Drift Velocity of Equatorial Plasma Bubbles During Ascending Phase of 24th Solar Cycle Using All‐Sky Imager Over Kolhapur, India

et al. 2018

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This paper reports the statistical analysis of zonal drift velocity of equatorial plasma bubbles (EPBs) inferred from advanced optical technique (all‐sky imager) with OI 630.0‐nm airglow emission from January to April of 2011 to 2013. Over 143 nights of observations have been carried out using all‐sky imager over low‐latitude station Kolhapur (16.8°N, 74.2°E; 10.6°N dip latitude), out of which 58 nights showed signatures of EPBs. We study the hourly, monthly, and seasonal variation in zonal drift velocity of EPBs. Also, the magnetically disturbed nights (Ap > 18) are separately studied. It is observed that (a) the daily peak zonal drift velocity is seen to be positively correlated to corresponding daily averaged 10.7‐cm solar flux. (b) The zonal drift velocity is found to be larger in the equinox months than that of winter months. (c) During the disturbed nights the zonal drift velocity gets slower and one of the disturbed nights showed the latitudinal variation in zonal drift velocity during the development phase of EPBs before midnight hours. We suggest that this variation might be occurred due to the disturbance dynamo electric fields at low latitude, which reduces the EPBs' eastward velocity. (d) The zonal drift velocity of EPBs presented in this paper is in good agreement with the previous studies as well as the HWM‐07 model values.

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Measurements of equatorial plasma depletion velocity using 630 nm airglow imaging over a low‐latitude Indian station

Cited by 23 publications

References 37 publications

First results on low‐latitude E and F region irregularities obtained using the Gadanki Ionospheric Radar Interferometer

First results on low‐latitude E and F region irregularities obtained using the Gadanki Ionospheric Radar Interferometer

Shrinking equatorial plasma bubbles

Zonal Drift Velocity of Equatorial Plasma Bubbles During Ascending Phase of 24th Solar Cycle Using All‐Sky Imager Over Kolhapur, India

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