Postmidnight bubbles and scintillations in the quiet‐time June solstice

Yizengaw, E.; Retterer, J. M.; Pacheco, E.; Roddy, P. A.; Groves, K. M.; Caton, R. G.; Baki, P.

doi:10.1002/2013gl058307

Cited by 96 publications

(120 citation statements)

References 22 publications

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“…This peak located between 21 and 22 LT during the quiet times for all seasons and during the disturbed times for the March and September equinox seasons (Su et al 2006). The post-midnight equatorial plasma irregularities are relatively rare events; more observations of the post-midnight plasma bubbles and longitudinally broad depletions (trenches) have been reported recently with the C/NOFS satellite (e.g., Burke et al 2009;Yizengaw et al 2013). Thus, the temporal interval of 20-23 LT should provide a major contribution to the occurrence rate probability of equatorial irregularities.…”

Section: Resultsmentioning

confidence: 79%

GPS and in situ Swarm observations of the equatorial plasma density irregularities in the topside ionosphere

2016

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Here we study the global distribution of the plasma density irregularities in the topside ionosphere by using the concurrent GPS and Langmuir probe measurements onboard the Swarm satellites. We analyze 18 months (from August 2014 till January 2016) of data from Swarm A and B satellites that flew at 460 and 510 km altitude, respectively. To identify the occurrence of the ionospheric irregularities, we have analyzed behavior of two indices ROTI and RODI based on the change rate of total electron content and electron density, respectively. The obtained results demonstrate a high degree of similarities in the occurrence pattern of the seasonal and longitudinal distribution of the topside ionospheric irregularities derived from both types of the satellite observations. Among the seasons with good data coverage, the maximal occurrence rates for the post-sunset equatorial irregularities reached 35-50 % for the September 2014 and March 2015 equinoxes and only 10-15 % for the June 2015 solstice. For the equinox seasons the intense plasma density irregularities were more frequently observed in the Atlantic sector, for the December solstice in the South American-Atlantic sector. The highest occurrence rates for the post-midnight irregularities were observed in African longitudinal sector during the September 2014 equinox and June 2015 solstice. The observed differences in SWA and SWB results could be explained by the longitude/LT separation between satellites, as SWB crossed the same post-sunset sector increasingly later than the SWA did.

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Section: Resultsmentioning

confidence: 79%

GPS and in situ Swarm observations of the equatorial plasma density irregularities in the topside ionosphere

2016

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“…The figure clearly shows activity in all seasons and strong bubbles/irregularities in the African sector compared to other longitudinal sectors. Recently, Yizengaw et al (2013b) reported significantly strong bubbles in the African sector during post-midnight local time under magnetically quiet conditions in June solstice. The question is if the drift is weaker in the African sector, what causes these strong bubbles that have been observed in the African sector almost throughout the night and during all seasons?…”

Section: Discussionmentioning

confidence: 99%

The longitudinal variability of equatorial electrojet and vertical drift velocity in the African and American sectors

et al. 2014

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Abstract. While the formation of equatorial electrojet (EEJ) and its temporal variation is believed to be fairly well understood, the longitudinal variability at all local times is still unknown. This paper presents a case and statistical study of the longitudinal variability of dayside EEJ for all local times using ground-based observations. We found EEJ is stronger in the west American sector and decreases from west to east longitudinal sectors. We also confirm the presence of significant longitudinal difference in the dusk sector pre-reversal drift, using the ion velocity meter (IVM) instrument onboard the C/NOFS satellite, with stronger pre-reversal drift in the west American sector compared to the African sector. Previous satellite observations have shown that the African sector is home to stronger and year-round ionospheric bubbles/irregularities compared to the American and Asian sectors. This study's results raises the question if the vertical drift, which is believed to be the main cause for the enhancement of Rayleigh-Taylor (RT) instability growth rate, is stronger in the American sector and weaker in the African sector -why are the occurrence and amplitude of equatorial irregularities stronger in the African sector?

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“…Since these irregularities often exist inside plasma bubbles, they have long been regarded as indications for EPBs (Abdu et al, 2003;Basu et al, 1980;Demyanov et al, 2012;Lühr et al, 2014;Ma & Maruyama, 2006;Park et al, 2005;Rama Rao et al, 2009;Rodrigues et al, 2009;Xiong et al, 2016;Yizengaw et al, 2013;Yokoyama et al, 2007). Since these irregularities often exist inside plasma bubbles, they have long been regarded as indications for EPBs (Abdu et al, 2003;Basu et al, 1980;Demyanov et al, 2012;Lühr et al, 2014;Ma & Maruyama, 2006;Park et al, 2005;Rama Rao et al, 2009;Rodrigues et al, 2009;Xiong et al, 2016;Yizengaw et al, 2013;Yokoyama et al, 2007).…”

Section: Data and Analysis Methodsmentioning

confidence: 99%

Plasma Blobs Concurrently Observed With Bubbles in the Asian‐Oceanian Sector During Solar Maximum

et al. 2019

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With simultaneous ionospheric measurements from ROCSAT‐1 satellite and ground ionosondes/GPS receivers, three cases of concurrent plasma blobs and bubbles in the same magnetic meridian were observed around 22:30 LT in Asian‐Oceanian sector during solar maximum. Two cases were observed: equatorial spread F (ESF) over Vanimo station (geog. 2.7°S, 141.3°E; geom. 11.2°S, 146.2°W) and plasma blobs around 8.0°S (geom.) on 1 June and 6 October 2003. The other case observed equatorial spread F over Hainan station (geog. 19.5°N, 109.1°E; geom. 9.1°N, 179.1°W) and plasma blob near the dip equator on 8 March 2004. Plasma blobs were all observed near 600‐km height near the equator. Equatorial spread F and amplitude scintillations from the ground stations were observed near the same magnetic meridian, indicating the existence of bubbles. Considering that both plasma bubbles and blobs are field‐aligned elongated structures, magnetic field line mapping shows that in the two cases at Vanimo, blobs were above bubbles, providing direct observational evidence for blob formation in the intermediate stage of plasma bubble evolution; in the case at Hainan, the blob and bubble were likely at similar height, and it could be generated by gravity wave.

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Postmidnight bubbles and scintillations in the quiet‐time June solstice

Cited by 96 publications

References 22 publications

GPS and in situ Swarm observations of the equatorial plasma density irregularities in the topside ionosphere

GPS and in situ Swarm observations of the equatorial plasma density irregularities in the topside ionosphere

The longitudinal variability of equatorial electrojet and vertical drift velocity in the African and American sectors

Plasma Blobs Concurrently Observed With Bubbles in the Asian‐Oceanian Sector During Solar Maximum

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