A study on the night time equatorward movement of ionization anomaly using thermospheric airglow imaging technique

Narayanan, Viswanathan Lakshmi; Gurubaran, S.; Emperumal, K.; Patil, P. T.

doi:10.1016/j.jastp.2013.03.028

Cited by 21 publications

(21 citation statements)

References 21 publications

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“…The MBW, resulting from the midnight pressure bulge (MPB) occurring in the midnight sector of the equatorial thermosphere, however, is expected to propagate poleward in off-equatorial regions near midnight [Narayanan et al, 2014]. In our case, the southward velocity of the SMEBAR is about 27.8 m/s (100 km/h), which is comparable to the velocity of EIA crest reported by Narayanan et al [2013] in India. Thus, the equatorward moving BBAR in our airglow observations should be the EIA crest, not the MBW.…”

Section: 1002/2016ja023223supporting

confidence: 70%

“…Narayanan et al [2014] pointed out that both EIA and midnight brightness wave (MBW) [Colerico and Mendillo, 2002] can pass through the nighttime ionosphere and interact with nighttime medium-scale traveling ionospheric disturbances (MSTIDs) and EPBs. The EIA crest decays after sunset and drifts equatorward to lower latitudes [Narayanan et al, 2013[Narayanan et al, , 2014. The MBW, resulting from the midnight pressure bulge (MPB) occurring in the midnight sector of the equatorial thermosphere, however, is expected to propagate poleward in off-equatorial regions near midnight [Narayanan et al, 2014].…”

Section: 1002/2016ja023223mentioning

confidence: 99%

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Evolution processes of a group of equatorial plasma bubble (EPBs) simultaneously observed by ground‐based and satellite measurements in the equatorial region of China

Sun

Wang

et al. 2017

JGR Space Physics

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This paper for the first time reports conjugate observations of a group of evolving equatorial plasma bubbles (EPBs) generated in the longitudinal sector of China on 4/5 November 2013 using simultaneous airglow and Communication/Navigation Outage Forecasting System (C/NOFS) observations. The airglow depletion structures seen by two all‐sky airglow imagers had the same zonal wavelength as that of the longitudinally periodic electron density depletions observed by the C/NOFS satellite which occurred at almost the same time but at magnetically conjugate latitudes. Data from a VHF radar and a Digisonde were combined to investigate the evolution of the EPB group, including their generation, development, and dissipation. Results indicate that the EPB group developed from the bottomside large‐scale wave‐like structure (LSWS) at about 195–210 km height with a characteristic zonal wavelength and longitudinal extension of about 450 km and 2250 km, respectively. The EPB group also caused periodic bottomside type spread F associated with the LSWS. We found that the development of the EPB group and their associated spread F could be limited by the equatorward motion of equatorial ionization anomaly (EIA) and the southwestward motion of an extremely bright airglow region (SMEBAR). The SMEBAR is a newly discovered structure of plasma density increase but not a plasma blob reported before. Both EIA and SMEBAR could feed high plasma density into an EPB airglow depletion structure that was eventually seen as a bright airglow structure or disappeared. Meanwhile, spread F associated with the EPBs did not evolve from the bottomside type into the strong range type.

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Section: 1002/2016ja023223supporting

confidence: 70%

Section: 1002/2016ja023223mentioning

confidence: 99%

Evolution processes of a group of equatorial plasma bubble (EPBs) simultaneously observed by ground‐based and satellite measurements in the equatorial region of China

Sun

Wang

et al. 2017

JGR Space Physics

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“…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. Detailed information about the instrument, 3 month campaign at Panhala, observation routines, and data analysis methods are discussed in detail in earlier works [Narayanan et al, 2009[Narayanan et al, , 2011[Narayanan et al, , 2013. The different airglow emissions are observed with the help of interference filters of~2 nm bandwidths except for OH emission observed with a broadband notch filter.…”

Section: Databasementioning

confidence: 99%

“…However, since the instrument has six interference filters to probe both mesospheric and thermospheric airglow lines and was operated manually, the sequence was interrupted often when some interesting events were found to occur in some of the emissions. Therefore, it becomes difficult to use keograms for analysis of the campaign data [Narayanan et al, 2013].…”

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 instrument comprises a six-position filter wheel to observe both mesospheric and thermospheric emissions. The details of the instrument, observation routines, and the basic data analysis techniques employed here can be found in Narayanan et al [2009Narayanan et al [ , 2012Narayanan et al [ , 2013. The manual observation routine usually involved acquisition of a few successive images of a particular filter for a prolonged duration depending on whether any interesting features were observed in that emission.…”

Section: Databasementioning

confidence: 99%

Direct observational evidence for the merging of equatorial plasma bubbles

2016

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In this work we present direct ground‐based observational evidence for the merging of individual equatorial plasma bubbles (EPBs) obtained through the imaging of OI 630.0 nm airglow. Three potential mechanisms have been identified: (1) One of the EPBs tilts and reaches location of the adjacent growing EPB finally merging with it. (2) Some of the branches of an EPB arising from secondary instabilities reach out to adjacent EPB and merge with it. (3) The eastward zonal drift of the EPB on the eastern side slows down while the adjacent EPB on the western side drifts relatively faster and catches up. In one of the cases, a branch of an EPB was observed to get interchanged with another EPB as a result of merging and consequent pinching off from the parent EPB.

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A study on the night time equatorward movement of ionization anomaly using thermospheric airglow imaging technique

Cited by 21 publications

References 21 publications

Evolution processes of a group of equatorial plasma bubble (EPBs) simultaneously observed by ground‐based and satellite measurements in the equatorial region of China

Evolution processes of a group of equatorial plasma bubble (EPBs) simultaneously observed by ground‐based and satellite measurements in the equatorial region of China

Shrinking equatorial plasma bubbles

Direct observational evidence for the merging of equatorial plasma bubbles

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